CA2661579A1 - Helical conduit hydrocyclone methods - Google Patents

Abstract

Methods for using hydrocyclones comprising helical conduits ahead of hydrocyclone open vessels are disclosed. The helical conduits may be in the form of coils or of spirals and may contain nozzles mounted in the walls of the conduits to inject fluids into suspension flowing through the conduits. The fluids may include gas under pressure, gas dissolved in liquids, collectors, activators, depressants, modifiers or frothers. The methods of the present invention are used to separate bitumen from oil sand suspensions or to separate comminuted minerals from gangue. The described and claimed hydrocyclone methods make use of centrifugal force fields to perform rapid froth flotation and produce underflow and overflow streams which, in some cases, may be deaerated and dewatered by an aperture oleophilic wall.

Description

Jan Kruyer, Thorsby, Alberta, Canada HELICAL CONDUIT HYDROCYCLONE METHODS
RELATED APPLICATIONS
This application is related to U.S. Patent Application No. 11/940,099, entitled "Hydrocyclone and Associated Methods ", filed November 14, 2007, U.S. Patent Application No. 12/132,165, entitled "Removal of Bitumen from Slurry Using a Scavenging gas ", filed June 3, 2008, Canadian Patent Application No. 2,638,550, entitled "Hydrocyclone and Associated Methods", filed August 7, 2008. Note that Canadian patent application

2,638,550 is a combination of US patent applications 11/940,099 and 12/132,165 but U.S.
application 11/940,099 did not disclose nor make any claims for gas injection.
The present application is also related to Canadian Patent Application No. 2,644,793 entitled "Endless Cable System and Associated Methods", filed August 6, 2008, and Canadian Patent Application No. 2,647,855 entitled "Design of Endless Cable Multiple Wrap Bitumen Extractors ", filed January 15`" 2009, which are each incorporated herein by reference.
FIELD OF THE INVENTION
The present invention relates to methods for hydraulically sorting and/or chemically reacting of flowing aqueous suspensions in a centrifugal force field with the assistance of one or more fluids injected into a conduit comprising a helical pipe, tube or hose in the form of a coil or spiral ahead of a hydrocyclone open vessel, and the resulting issuance of an overflow stream and an underflow stream from the open vessel. Accordingly, the present invention involves the fields of process engineering, chemistry, and chemical engineering.
BACKGROUND OF THE INVENTION
As described in the above referenced patent applications, oil sands, also known as tar sands or bituminous sands, may represent up to two-thirds of the world's petroleum reserve.
In the past, oil sands resources remained relatively untapped. Perhaps the largest reason for this was the difficulty of extracting bitumen from the sands. Large deposits of mineable oil Jan Kruyer, Thorsby, Alberta, Canada sand ore are found in the Fort McMurray region of Alberta, Canada, and elsewhere. This oil sand includes sand grains having viscous bitumen trapped between the grains.
The bitumen can be liberated from the sand grains by suspending the as-mined oil sand particulates in water so that the bitumen flecks disengage from the sand grains and disperse in the aqueous phase for separation. For the past 50 years, bitumen in McMurray oil sand has been commercially recovered using the original Clark Hot Water Extraction process, along with a number of improvements. Karl Clark invented his original process at the University of Alberta and at the Alberta Research Council around 1930 and improved it for over 30 years before it was commercialized. The present inventor knew Karl, and after Dr.
Clark retired, the inventor used some of the pilot plant space previously occupied by Clark at the Alberta Research Council to commence the development his own oil sands process and overcome some of the problems of the Clark process.
In general terms, the conventional Clark hot water process, and its commercial improvements, involve mining oil sands ore at a remote mine site. The mined ore is then transported to a bitumen extraction plant by earth haulers or by slurry pipeline. The ore is mixed with water and chemicals to condition it to disengage the bitumen particles from the sand matrix and form a slurry. This slurry may be conditioned by turbulence in a pipe during pipeline transportation between mine site and an extraction plant or it may be conditioned at the extraction plant in large tumblers that mix water and/or steam with the oil sand ore.
Large rocks are removed from the slurry, either by screening the tumbler product or by crushing the ore before it enters the pipeline. Normally caustic soda, a process aid, is added to the slurry to disperse the mineral particles and to produce detergents by chemical reaction with components in the ore, which detergents enhance subsequent bitumen recovery. The slurry may be further diluted with water and is then pumped into a primary separation vessel (PSV) where it is separated by froth flotation. Bitumen particles adhere to air bubbles in the PSV and cause bitumen to float as froth to the top of the vessels to be skimmed off.
Clark separation produces three components: an aerated bitumen froth which rises to the top of the PSV; primary tailings which settle to the bottom of the PSV;
and middlings which concentrate in the middle of the PSV. The bitumen froth is skimmed off the top as the Jan Kruyer, Thorsby, Alberta, Canada primary bitumen product. The middlings are pumped from the middle of the PSV
to sub-aeration flotation cells to recover additional aerated bitumen called secondary bitumen product. The primary tailings from the PSV, along with secondary tailings product from flotation cells are pumped to the shore of a tailings pond, usually adjacent to the extraction plant, for impounding. The tailings sand drops out on the beach and is used to build dykes around the pond and the aqueous residue including water, detergents, caustic, silt, clay, and residual bitumen flow into the pond to settle for a decade or more, forming non-compacting sludge layers near the bottom of the pond. Clarified water, containing detergents, caustic, salts, and a small amount of fines eventually rises to the top of the pond for reuse in the process.
The primary and secondary bitumen froth are combined and treated to remove air and then diluted with diluent, such naptha and centrifuged to produce a bitumen product suitable for upgrading. Centrifuging also creates centrifugal tailings that contain mainly solids, water, residual bitumen, and naptha, which are disposed of in the same or in another tailings ponds.
In an alternate process the produced bitumen is extracted with a straight chain hydrocarbon liquid to remove water solids and a small amount of asphaltenes by settling, for example in a vessel, to produce a bitumen product suitable for upgrading or shipping by pipeline to a refinery, and yielding an aqueous tailings product, containing some dispersed asphalt, sent to a tailings pond.

The residence time in a Clark extraction plant, comprising the time it takes from mining the ore to producing the bitumen froth and disposing of the tailings, is a function of the complexity of the commercial plant designed to achieve acceptable bitumen recovery. It normally is several hours. Residence time in the PSV alone can be between 30 and 60 minutes to produce primary froth, with additional time taken in the subaeration cells to produce secondary froth and in the tailings clean up equipment.
Some major improvements have been made in the Clark process that include lowering the separation temperature in the tumbler, in the PSV, and in the flotation cells by the addition of a small amount of a hydrocarbon diluent to the slurry. This reduces the energy costs to a degree but may also require the use of larger tumblers and the addition of

3 Jan Kruyer, Thorsby, Alberta, Canada more air to enhance bitumen flotation. Another improvement eliminated the use of bucket wheel excavators, draglines and conveyor belts to replace these with large shovels and huge earth moving trucks. Later improvements replaced some of these trucks and most of the costly and high maintenance conveyors with a slurry pipeline. Such a pipeline transports the ore as a mixture in water and eliminates the expense of mechanical transport of the ore from the mine site to the separation plant. A slurry pipeline also eliminates the need for conditioning tumblers. Turbulence in a slurry pipeline about 3 kilometers or longer normally achieves the desired conditioning. However, an oil sand slurry pipeline requires the use of one or more oil sand ore crushers to prevent pipe blockage by rocks or oil sand lumps, tree trunks, etc., and also requires a cyclo-feeder to mix the crushed ore with water and to aerate the oil sand as it enters the slurry pipeline. An oil sand slurry pipeline may also require compressed air injection into the slurry at one or several points along into the pipeline.
Other recent improvements in the commercial Clark process include tailings oil recovery units to scavenge additional bitumen from the tailings, and naptha recovery units for processing the centrifugal tailings before these enter the tailings ponds.
More recent research is concentrating on efforts to convert the fluid tailings or sludge in the tailings ponds to compact these tailings and remediate them. For example,lime, gypsum and/or flocculants may be added to the sludge of the tailings ponds after it has settled for one or more decades, to compact the fines and release additional water. Most of the improvements made to the commercial Clark process have served to make the process more attractive economically, by increasing the amount of bitumen recovered, by eliminating expensive transportation equipment and by reducing the amount of energy required. These, however, have also served to increase the complexity of the commercial oil sands plants without doing much to overcome the associated environmental problems of oil sands processing.
One particular problem that has vexed commercial mined oil sands plants is the problem of fluid fine tailings disposal. Caustic soda serves as a process, aid to produce detergents by reacting with components in the oil sand ore and also serves to disperse the oil sand fines and thus reduce the viscosity of the slurry suspension in the PSV.
Reducing this suspension viscosity allows the aerated bitumen droplets to travel to the top of the separation

4 Jan Kruyer, Thorsby, Alberta, Canada vessels by gravity fast enough to achieve satisfactory bitumen recovery in a reasonable amount of time. A graph of the rise velocity of bitumen droplets in a PSV is supplied in FIG. 3D to illustrate that bitumen rises about 16 times as fast in a dispersed suspension as compared with a suspension that is not dispersed. Electrical charges are imparted to the oil sand fines as a result of process aid additions, especially the clay particles are charged, which charges repel and disperse these particles and thereby reduce the viscosity of the dilutedPSV
slurry. When pond water is recycled to the process, this process aid and/or the produced detergents, already are present in the water used to prepare the oil sand slurry or suspension.
When process aid, or recycle water is not used, the diluted slurry of most oil sands would be too viscous for effective bitumen recovery in the PSV and in the subaeration flotation cells.
The graph shows a bitumen rise rate increase of about sixteen, but even three times the required residence time would make commercial oil sands extraction too expensive and impractical.
While process aid is beneficial for producing detergents and as a viscosity breaker in the separation vessels for floating off bitumen, it is environmentally very detrimental. The detergents produced from naphthenic acid components in the oil sand slurry are highly toxic.
Not only are the tailings toxic, but due to the electrical charges and other components that are present, the tailings fines take a very long time to settle and compact.
Tailings ponds with a combined average circumference as large as 20 kilometers are required at each large mined oil sands plant to contain these fine fluid tailings. Coarse sand tailings are used to build huge and complex dyke structures around these ponds. The very small particles of the fluid fine tailings cause the formation of very thick layers of microscopic card house structures and jells that compact extremely slowly and take decades or centuries to reach a solids content between 30 and 40 weight percent and a water content between 60 and 70 percent. Due to partial sludge compaction, water rises to the top of the ponds, and this water contains salts, process aid, and detergents and is reused in the extraction plants many times over as recycle water. In some cases this water may be treated before it is used a recycle water. For mature commercial oil sands plants the amount of pond recycle water used in the extraction may be five or ten times as much as the amount of fresh water used for the extraction. The residual

5 Jan Kruyer, Thorsby, Alberta, Canada process aid and detergents in the recycle water tend to significantly reduce the requirements for fresh caustic process aid additions to the oil sand slurry in these plants. However, the amount of dispersed fluid tailings accumulating in the ajacent oil sands tailings ponds is staggering. For example, the current amount of stored fluid tailings (sludge) could cover a 10 meter wide (two lane) highway 12 meters high (up to the rafters of a four story building) all the way across Canada from Victoria to Hallifax. Many millions of dollars per year have been and are being spent in an effort to maintain the tailings ponds and to find effective ways to dewater these tailings. Several patents have been granted to or are pending for the present inventor to solve some of the above described environmental problems and to reduce the cost of equipment, chemicals and energy of the current commercial oil sands extraction plants.
In one application of the art, the Kruyer process uses a revolving apertured oleophilic wall to separate aqueous oil sand suspensions. The oil sand suspension flows to the wall which allows hydrophilic solids and water to pass through the wall apertures whilst capturing bitumen and associated oleophilic solids by adherence to the surfaces of the revolving oleophilic wall. Oversize solids are solids that have dimensions approaching the dimensions of the wall apertures in at least one dimension, and these are removed before the mixture is separated by the apertured wall. Removal of such oversize may be done by the use of hydrocyclones independently or in conjunction with screens ahead of the aperture wall. Such hydrocyclones are disclosed in copending patent applications and in the current application.
Other uses of these hydrocyclones are also possible as, for example, in the froth flotation of an aqueous suspension of comminuted mineral ore in a centrifugal force field.
Along the revolving apertured oleophilic wall, there are one or more separation zones to separate the suspension into an effluent of water with hydrophilic solids and a product of bitumen and oleophilic solids. Along the same revolving apertured wall are one or more recovery zones where the recovered bitumen and oleophilic solids are removed from the wall. This product normally is not an aerated froth but rather a viscous liquid bitumen. A
prior bitumen-agglomerating step may be required to increase the bitumen particle size before the suspension passes to the apertured oleophilic wall for separation..
This Kruyer process was tested extensively and was successfully implemented in a pilot plant with high

6 Jan Kruyer, Thorsby, Alberta, Canada grade mined oil sands (12 wt% bitumen), medium grade mined oil sands (10 wt%
bitumen), low grade oil sands (6 wt% bitumen) and with fluid tailings (sludge) from commercial oil sands tailings ponds (down to 2% wt% bitumen), the latter at separation temperatures as low as 5 degrees centigrade.
A large number of patents have been granted for the Kruyer process in Canada and in the U.S. representing prior art. In this prior art the apertured oleophilic wall took the form of a drum only with aperture cylindrical wall or took the form of conventional mesh belts which worked fine in the pilot plant for a few weeks but fell apart after extended use. Conventional commercial steel conveyor belts were tested and patented also but these did not perform as well as the mesh belts. Years later a new type of aperture oleophilic wall was developed that made use of one or more revolving endless cables that were wrapped around rollers and rums in the form of multiple wraps. The multiple wraps formed the surface of the apertured oleophilic wall and the slits or spaces between sequential cable wraps formed the apertures.
Various still pending patent applications disclose and claim a large variety of applications that make use of the multiple cable wrap aperture oleophilic wall. Other patents are pending for apparatus or methods to augment or support the use of such an aperture oleophilic wall that uses cable wraps, but may also be used in conjunction with the prior art that uses mesh belts or conventional commercial steel conveyor belts. The claims of these copending patents may be used independently and in many cases may not require the use of an aperture oleophilic wall altogether.
Froth flotation in the PSV of the Clark process requires a residence time of about to 45 minutes and additional time is taken in the sub-aeration cells to achieve acceptable bitumen recovery. Since froth flotation relies on the force of gravity for its effectiveness, much shorter residence times can be achieved when a centrifugal force 25 field is applied to the slurry, especially when this force field is one or more orders of magnitude greater than the force of gravity. The present invention takes advantage of this greater force field to achieve much faster bitumen froth flotation than is possible in a gravity force driven system. The present invention makes use of a hydrocyclone of special design which allows the introduction of fluid from jets into a flowing oil sand

7 Jan Kruyer, Thorsby, Alberta, Canada suspension while the suspension is under the influence of a centrifugal force field in a curved conduit, such as a pipe, tube or hose curved into a coil or a spiral, and before it is separated into an overflow and an underflow by the open vessel of a hydrocyclone.
The hydrocyclone design of the present invention includes a curved conduit ahead of an open vessel of the hydrocyclone to prepare a flowing suspension for the subsequent separation by the open vessel into an overflow and an underflow. Provision is made for the injection of one or more fluids under pressure through the conduit wall into the flowing suspension. This injected fluid may be a gas, a liquid, a gas dissolved in a liquid under high pressure, a chemical dissolved in a liquid, or it may be a finely dispersed aqueous suspension, such as milk of lime, finely dispersed gypsum in water or a fine suspension of another divalent or trivalent salt in water. Several fluids may be injected into the conduit in sequence. This, for example, may be done to allow one process operation to precede another process operation or reaction in the suspension flowing through the conduit.
When the flowing suspension contains particulate matter of varying sizes or of varying densities, the coarse or dense particles will tend to gravitate towards the outer lane of the conduit and the fine or less dense particles will tend to gravitate towards the centre or towards the inner lane of the conduit due to its curvature. This is similar to the forces exerted on a passenger in a car that rapidly turns a corner. Jets or nozzles may be mounted in the conduit wall to inject fluid into the suspension, or a short section of the conduit wall may be made porous and this porous section may be surrounded by a chamber containing injection fluid under pressure. The injected fluid may include large amounts of gas or liquid, causing bitumen and fine particles to dislodge from the larger particles and move out of the outside lane towards the middle of the conduit or to the inside lane. The injected fluid may cause the adherence of bitumen particles and/or hydrophobic particles to gas bubbles and result in the froth flotation of these particles out of the outside lane and into the centre or into the inside lane of the curved conduit under the influence of the centrifugal force field present in the suspension flowing in the conduit. In one objective, an abundance of gas is injected to achieve froth flotation of

8 Jan Kruyer, Thorsby, Alberta, Canada selected components of the suspension in a centrifugal force field.
Alternately, a much smaller amount of air or gas may be may be injected through nozzles throug the conduit wall, as described in Canadian copending patent application "Hydrocyclone and Associated Methods ". In this copending application the amount of injected air or gas was limited to allow the bulk of the liquid suspension to absorb this air or gas after it had done its job of transferring bitumen to the inside lane. In contrast, the objective of the present invention is to inject an abundance of gas into the flowing suspension through the conduit walls to retain all or most of the bitumen in the suspension in an aerated form as froth.
This froth then reports, along with water and fines, to the overflow of the hydrocyclone open vessel of the present invention. The overflow product mixture may then sent to a separation apparatus that uses an aperture oleophilic wall to remove air, water and some solids to yield a valuable liquid bitumen product and a discard tailings product. Unlike the other pending patent applications of the same inventor, this current application also expands the concepts of froth flotation in a centrifugal force field to the separation of comminuted ore into valuable minerals and gangue.
Thus, in the present invention, the amount of air or gas used is much larger than in the copending art and the overflow of the hydrocyclone contains at least 3%
air by volume, and in many cases much more. The current application also introduces the merits of using more than one hydrocyclone in series to optimize the quality of froth produced. The first hydrocyclone may be used to remove coarse solids from the oil sand slurry and fluid may be injected through the walls of the conduit to assist in the transfer of bitumen and fines from the outside lane to the middle or to the inside lane. In subsequent hydrocyclones that follow the first hydrocyclone in series, other fluids may be injected through the conduit walls of these hydrocyclones to refine the desired sorting, mixing, separation or reaction processes that may take place. For example, the first hydrocyclone may be larger in size than the subsequent hydrocyclone or hydrocyclones.
As a result, the flow velocity through the first hydrocyclone may be lower than through the subsequent hydrocyclones. This may result in the removal of very coarse solids from the suspension through the first underflow, while allowing a first overflow, containing

9 Jan Kruyer, Thorsby, Alberta, Canada less coarse solids, to become the feed for the helical conduit of a second but smaller hydrocyclone. In most cases the total flow through the first hydrocyclone will be larger than the flow through a subsequent hydrocyclone, even if both hydrocyclones are of the same size, since part of the flowing suspension is removed by the underflow of the first hydrocyclone. Therefore, the relative sizes of several hydrocyclones in series may be optimized to control the flow velocity and centrifugal force field in each hydrocyclone and thus achieve the objectives of the present invention for each hydrocyclone.
The methods of the present invention may be used to process oil sand suspensions, such as oil sand slurries, Clark process or other process middlings, primary tailings, secondary tailings, tailings pond sludge, tailings pond sediments or any other aqueous stream containing bitumen. However, it may also be used for froth flotation of size reduced mineral ores to float off the desired components by adhesion to gas bubbles while leaving undesirable components water wetted and in suspension or settling.
Alternately it may be used to float off undesireable gangue while leaving the desired components in aqueous suspension or settling.
The concepts of using a centrifugal force field to remove coarse solids from an oil sand slurry is disclosed and claimed in Canadian patent 2,246,841 entitled "Cycloseparator for removal of coarse solids from conditioned oil sand slurries" issued to Maciejewski et.al on 20 November 20`h, 2001 and reissued on Febuary 24`h, 2004. This patent discloses a very large hydrocyclone that produces an overflow consisting of bitumen froth and fines and an underflow of coarse solids in water. This patent does not disclose or claim a helical conduit nor any injection of fluid into such a helical conduit.
The concept of using air injection in a hydrocyclone to cause hydrophobic particles to adhere to air bubbles and report to the overflow is disclosed in a Canadian patent entitled "Air Sparged Hydrocyclone and Method" issued to Miller on January 4th, 1983.
This patent discloses a hydrocyclone provided with a gas jacket surrounding part of the hydrocyclone body, which jacket has a porous inner wall that allows entry of finely dispersed compressed gas into the hydrocyclone vessel to encourage adhesion of hydrophobic particles to the gas bubbles and cause these to report to the hydrocyclone Jan Kruyer, Thorsby, Alberta, Canada overflow. Another Canadian patent entitled "Flotation Apparatus for Achieving Flotation in a Centrifugal Field" issued to Miller on October 1st 1985 uses a very similar apparatus to separate minerals from gangue. A hydrocyclone body with separate inlets for air and slurry is disclosed in US patent 4,971,685 entitled "Bubble Injected Hydrocyclone Flotation Cell" issued to Stanley, et al. on November 20th 1990.
The use of two hydrocyclone vessels in one housing is disclosed in Canadian patent entitled "Hydrocyclone System Including Axial Feed and Tangential Transition Sections"
granted to Macierewicz et al. on October 9th, 1979. In this patent a stream of coarse solids is removed from the system by means of a helical screw flight section before the remainder is separated by a conventional hydrocyclone section into an underflow and an overflow.
In his granted US patent 4,838,434, issued June 13th, 1989, Dr. Miller provides a very detailed description of using air sparged hydrocyclone flotation methods for separating particles from a particulate suspension. He uses an upright generally cylindrical hydrocyclone vessel having a circular cross-section and a tangential inlet in the upper portion of the vessel for introducing a suspension in a generally tangential fashion; a means for introducing gas into the open vessel, to contact the suspension; the gas forming small bubbles, which combine with particles in the particulate suspension to form bubble/particle aggregate froth within the vessel. The vessel of the Miller patent has a porous cylindrical outside wall that is functionally connected to an air chamber surrounding the open vessel, which allows finely dispersed gas to enter the open vessel and contact the suspension. Again the Miller patent does not anticipate the use of a confined helical conduit ahead of a hydrocyclone vessel for fluid injection in a flowing suspension.
Flotation of minerals and the separation of minerals from gangue in conventional flotation vessels is described in detail by Somasundaran et. al. in his book entitled "Reagents in Mineral Technology" (ISBN 0-8247-7715-8) and Dr. Miller also provides an excellent review of minerals flotation in his above referenced patents. I
hereby defer to both authors as being experts in this field of engineering. Flotation is a process in which one or more specific particulate constituents of a slurry or suspension of finely dispersed Jan Kruyer, Thorsby, Alberta, Canada particles become attached to gas bubbles and form a "bubble and particle aggregate"
which can be separated from the other constituents of the slurry or suspension. The buoyancy of the bubble and particle aggregate, formed by the adhesion of gas bubbles to particles in the slurry or suspension, is such that the agregate rises to the surface of conventional flotation vessels where it is separated from the remaining particulate constituents which remain suspended in the aqueous phase of suspension in the separation vessel.

Hence, flotation techniques can be applied where conventional gravity separation techniques fail and, as a result, flotation has supplanted the older gravity separation methods in solving a number of separation problems. Flotation was used initially to separate sulphide ores of copper, lead, and zinc from associated gangue mineral particles but flotation is now also used for concentrating non-sulphide ores, for cleaning coal, for separating salts from their mother liquors, and for recovering elements such as sulphur and graphite. It also is used in the reclamation industry to separate plastic particles from other materials.
The application of flotation technology to mineral recovery during the past four decades has increased at an annular rate of more than 10%. , and present flotation installations in Canada, the United States and elsewhere in the world are capable of processing well over four million tons of material per day.
Preferred methods for removing the floated material involve the formation of froths or foams to collect the bubble/particle aggregates. Froths containing the collected bubble/particle aggregates can then be removed from the top of the suspension.
This process is called "froth flotation" and is conducted as a continuous process in equipment called flotation cells. Froth flotation is accomplished by the introduction into these flotation cells of voluminous quantities of small bubbles, which in the flotation cells of the prior art were typically in the range of from about 0.1 to about 2 millimeters in diameter.
In conventional flotation cells of the prior art, the success of flotation has depended upon controlling conditions in the particulate suspension so that the air is Jan Kruyer, Thorsby, Alberta, Canada selectively retained by one or more particle constituents and is rejected by the other particle constituents of the suspension. To achieve this selectivity, the slurry or particulate suspension is typically treated by the addition of small amounts of known chemicals or flotation enhancing reagent fluids which selectively render hydrophobic one or more of the constituents in the particulate suspension. Those chemicals which render hydrophobic a particulate constituent which is normally hydrophilic, are commonly referred to as "activators" or "collectors." Chemicals which increase the hydrophobicity of a somewhat hydrophobic particulate constituent are commonly referred to as "promoters." Treatment with a collector or promoter causes those constituents rendered hydrophobic to be repelled by the aqueous environment and attracted to the air bubbles.
Most importantly, the hydrophobic nature of the surface of these constituents enhances attachment of air bubbles to the hydrophobic constituents. Thus, control of the surface chemistry of certain particulate constituents by the addition of flotation enhancing reagent fluids such as a collectors or promoters allows for selective formation of bubble and particle aggregates with respect to those constituents.
Other chemicals or flotation enhancing fluids may be used to help create the froth phase for the flotation process. Such reagents or chemicals are commonly referred to as "frothers." The most common frothers are short chain alcohols, such as methylisobutylcarbinol (MIBC), pine oil, and cresylic acid. Important criteria related to the choice of an appropriate frother include the solubility and collecting properties of the frother, the toughness and texture of the froth, and froth breakage. Hence, an appropriate frother normally is chosen to ensure that the froth will be sufficiently stable to carry the bubble and particle aggregates for subsequent removal as a flotation product concentrate.
Dr. Miller refers to the term "concentrate" as a mixture of desired mineral product and other entrained minerals which are present in the froth product. He states that the proper choice of frother ensures that a froth will allow for the proper drainage of water and for the proper removal of misplaced hydrophilic particles from the froth; and that in practical flotation tests, the size, number, and stability of the bubbles formed during flotation can preferably be optimized at given frother concentrations. Other chemical solutions added Jan Kruyer, Thorsby, Alberta, Canada to the suspension include "modifiers" which comprise a broad class of organic or inorganic compounds that modulate the flotation environment by regulating solution chemistry, or by flocculating or dispersing particles in the suspension.
A complete flotation process may be conducted in several steps:
(1) A slurry is prepared containing from about five percent to about forty percent by weight solids in water;
(2) The necessary flotation enhancing reagent fluids are added, and sufficient agitation and time is provided to distribute the reagent on the surface of the particles to be floated;
(3) The treated slurry is aerated in a flotation cell by agitation in the presence of a stream of air or by blowing air in fine streams through the slurry; and (4) The aerated particles in the froth are withdrawn from the top of the cell as an overflow froth product, and the remaining solids and water are discharged from the bottom of the flotation cell.
A large amount of research and development work has been done in analyzing the various factors which relate to improving the conditions during flotation in order to obtain improved recovery of particles. One particular phenomenon that has been known for some time is the poor flotation response of fine particles. This becomes economically important when flotation separation methods are used in the processing of minerals.
Generally, prior art processes using gravity induced flotation, have achieved flotation for both metallic and nonmetallic minerals having particle sizes as large as about microns. In these processes, particles less than 10 to 100 microns in size are frequently difficult to recover. One factor in conventional froth flotation, which has limited the extent of fine particle recovery is the relatively slow rate at which fine particles are separated in the prior art flotation processes which use gravity as the driving force for separation. Very small particles take too long to rise to the top of flotation cells.
Frequently, the mineral industry has thus been forced to discard the smaller, unrecovered mineral particles since it is uneconomical to concentrate or recover them. The economic losses suffered by the minerals industry due to this inability to recovery very fine Jan Kruyer, Thorsby, Alberta, Canada minerals by conventional flotation techniques indeed is staggering. For example, in the Florida phosphate industry, approximately one-third of the phosphate is typically lost in the residual waste slime. Roughly, one-fifth of the world's tungsten and about one-half of Bolivian tin is lost due to the inefficiencies of the flotation techniques of the prior art currently used in recovery processes for these minerals. The inability of the prior art of gravity flotation processes to recover fine particles also is an important economical and environmental issue in the coal industry. Flotation processes for separating ash and sulphur from coal have been used with greatly increased frequency during recent years.
However, in these flotation separation processes, significant amounts of very fine coal particles are not recovered but leave with the effluent. Not only is this a waste of a valuable resource, but disposal of finely dispersed coal-containing aqueous reject streams is frequently a serious environmental problem.
A major factor which impacts on the effectiveness of conventional flotation is that conventional flotation cells generally require a minimal retention time of at least two minutes for successful separation. This relatively long retention time required for conventional flotation processes limits the separation plant capacity and necessitates the construction of large equipment which result in large floor space demands and requires high capital and maintenance expenditures.
Unlike the hydrocyclone disclosed and claimed in the Miller patents, the present invention does not use froth flotation hydrocyclones requiring a porous wall between the hydrocyclone open vessle and a surrounding gas chamber. Rather, it uses a conduit ahead of a hydrocyclone open vessel where the conduit is formed into a coil or a spiral to impose a centrifugal force field on the flowing suspension well before it enters the open vessel or drum of the hydrocyclone, and fluids, including gas are injected through the conduit wall into the flowing suspension. Hence, the present invention does not use a porous wall for the open vessel of the hydrocyclone nor an air chamber surrounding the open vessel.
The present invention uses a helical conduit ahead of the open vessel of the hydrocyclone to establish a centrifugal force field in the flowing suspension well before Jan Kruyer, Thorsby, Alberta, Canada the suspension enters the open vessel of the hydrocyclone. Consistent with the above descriptions of minerals flotation, activators may be used to prepare the minerals for flotation, suppressors may be used to prevent other minerals from flotation, modifiers may be used to regulate the solution chemistry of the suspension and frothers may be used to encourage certain components to adhere to gas bubbles and gas may be injected into the suspension to achieve the desired flotation.
Nozzles may be mounted in the conduit ahead of the hydrocyclone open vessel or porous sections of the conduit may be used to introduce these extra components, in the form of fluids under pressure, into the flowing suspension, which suspension is under the influence of a centrifugal force field due to its flow through the coil or spiral. Several different fluids may be injected in sequence through the wall of the conduit to achieve the desired reaction within the flowing suspension, to achieve the desired particle surface chemistry, to achieve the desired adherence to gas bubbles, and to achieve the desired sorting of the aerated (gas bubble added) suspension particulates according to size, density and/or surface characteristics before entering the open vessel of the hydrocyclone.
In the open vessel, the suspension assumes the form of a swirl path which splits into an aqueous underflow, containing coarse or dense or un-aerated, mostly hydrophilic particles, and an aqueous overflow containing fine or light and mostly hydrophobic aerated particles in the form of a froth.
In addition, one or more obstructions may be placed in the helical conduit to create turbulence in part of the conduit to thoroughly mix the added fluid locally with the suspension flowing in the conduit. The purpose of such an obstruction is to disrupt momentarily the sorting that takes place within the conduit in a centrifugal force field and to thoroughly mix at least part of the suspension with the injected fluid, after which the centrifugal force field in the conduit resumes its sorting influence on the suspension.
In some cases only one fluid may be injected through the wall of the conduit of a first hydrocyclone that is placed in series with one or more other hydrocyclones. Such a series configuration will produce an underflow and an overflow from this first hydrocyclone that will differ from the underflow and the overflow of a subsequent Jan Kruyer, Thorsby, Alberta, Canada hydrocyclone. The underflow or the overflow of the first hydrocyclone may then enter the conduit of a second hydrocyclone where a different fluid may be injected through the conduit wall to produce yet another overflow and underflow that differ in composition from each other and from the underflow or overflow of the first hydrocyclone.
In this manner two or more hydrocyclones of the present invention may be placed in series and the underflow and overflow of each hydrocyclone may differ in composition and flow rate from the underflow and overflow of a preceding hydrocyclone to achieve the objective of the present invention for the separation of a suspension.
The conduit ahead of the open vessel or drum of the hydrocyclone may be in the form of a pipe, a tube with round, square or rectangular cross section, or a hose, all of which may be formed into a coil or a spiral. Since a coil generally has a constant curvature, the force field within the suspension along coil length will be constant for a given flow rate of aqueous suspension in the coil. However, in the case of a spiral, the rate of curvature increase from beginning to end. Hence, the force field within the suspension along the spiral length for a given flow rate of suspension will increase progressively until the suspension reaches the inlet to the open vessel of the hydrocyclone.
In many cases there may be a further important benefit of providing a helical conduit ahead of the open vessel of the hydrocyclone since the pressure in the suspension at the entrance of the conduit always is greater than the pressure in the suspension leaving the conduit and entering the open vessel. For example, when very small air bubbles are injected in the suspension near the beginning of the conduit, these bubbles will expand as the pressure gradually decreases further down the conduit. Similarly, when a liquid under pressure containing a dissolved gas is injected through the wall of a helical conduit into the suspension nearer the entrance of the conduit, this gas may come out of solution to form gas bubbles that progressively increase in diameter further down the conduit towards the open vessel of the hydrocyclone where the pressure in the flowing suspension is lower.

Jan Kruyer, Thorsby, Alberta, Canada SUMMARY OF THE INVENTION

Accordingly, the present invention relates to froth flotation of an aqueous suspension in a centrifugal force field in one hydrocyclone or in several hydrocyclones in series, each hydrocyclone having a curved conduit in the form of a coil or spiral ahead of the hydrocyclone open vessel, in which each open vessel has an underflow outlet and has an overflow outlet that is operatively connected to a vortex finder inside each hydrocyclone open vessel.
The aqueous suspension to be processed by the present invention is a pumped suspension or is a flowing suspension stream under pressure which stream may comprise a suspension of oil sand ore that has been digested in water prior to entry into the conduit. It may comprise an oil sands middlings stream, an oil sands primary tailings stream, an oil sands secondary tailings stream, an oil sands tailings pond fluid tailings (sludge) stream, an oil sands aqueous stream from the upper levels of a tailings pond that contains the remains of undesirable solids in suspension; or it may be a suspension stream from the bottom of an oil sands tailings pond dredged from the bottom of the pond, or pumped out of the pond.
Alternately, the suspension may be an aqueous suspension of comminuted, crushed or ground mineral ore that contains valuable minerals and gangue from which the minerals are to be separated by flotation, or from which the gangue is to be separated by flotation from the minerals by the methods of the present invention. Alternately yet, it may be a suspension of salts, plastic particles, or comminuted recycle materials that may be separated into two or more components by the methods of the present invention.

FURTHER PROCESSING

The overflow product from a hydrocyclone of the present invention may contain air and water and undesirable residual minerals that preferably are removed before the product is used or processed further. Such removal may be achieved by passing the overflow product Jan Kruyer, Thorsby, Alberta, Canada through an aperture oleophilic wall as described in the prior art of the present inventor or as described in the above referenced copending patent applications entitled "Endless Cable System and Associated Methods, " and "Design of Endless Cable Multiple Wrap Bitumen Extrtactors ". When an aerated oleophilic froth is passed through an aperture oleophilic wall, water and air may be removed from the froth, and this in many cases will yield a dryer and more fluid product that contains little or no air and has a lower water content. In some cases the apertured oleophilic wall also will remove some solids that are less hydrophobic than the bulk of the froth, especially when the froth is agglomerated in an agglomerating drum described in the above referenced copending patent applications.
There has thus been outlined, rather broadly, various features of the invention so that the detailed description thereof that follows may be better understood, and so that the present contribution to the art may be better appreciated. Other features of the present invention will become clearer from the following detailed description of the invention, taken with the accompanying claims, or may be learned by the practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. I A is a side view of a hydrocyclone with a conduit in the form of a coil and an open vessel with a conical bottom for an axial underflow outlet. FIG. I B is a plan view of the same. FIG. 1 C is a side view of a hydrocyclone with a conduit in the form of a coil and an open vessel with a conical bottom for a tangential underflow outlet. FIG. 1 D is a plan view of the same.FIG. I E is a side view of a hydrocyclone with a conduit in the form of a coil and an open vessel of generally constant diameter and with a tangential underflow outlet. FIG.
1 F is a plan view of the same.
FIG. 2A is a side view of a hydrocyclone with a conduit in the form of a spiral and an open vessel with a tangential underflow outlet. FIG. 2B is a plan view of the same. FIG. 2C is an internal view of a section of the conduit.
FIG. 3A is a side view of a hydrocyclone with a conduit in the form of a spiral and an open vessel with a tangential underflow outlet at the bottom and an axial overflow outlet at the top. FIG. 3B is a side view of a hydrocyclone with a conduit in the form of a spiral and an open Jan Kruyer, Thorsby, Alberta, Canada vessel with a tangential outlet at the bottom and an axial overflow outlet at the bottom. FIG. 3C
is a side view of a hydrocyclone with a conduit in the form of a spiral and an open vessel with a conical axial underflow outlet at the bottom and an axial overflow outlet at the top. FIG. 3D is a graph of the rise velocity of a bitumen droplet as a function of drop diameter in a Clark process PSV in which fresh water was used for producing the oil sand slurry, comparing the rise velocity of bitumen droplets in a slurry containing conventional caustic soda process aid and the corresponding rise velocity of biutmen droplets in a slurry not containing any process aid.
FIG. 4A is a plan view of a hydrocyclone with a conduit in the form of a spiral showing flange connections within the spiral. FIG. 4B to 4D are enlarged internal views to better illustrate these Figures. FIG. 4B is an internal view of a section of the conduit of FIG. 4A near a set of flanges, which are provided with a straight flange insert to provide disturbance and mixing in the conduit. FIG. 4C is an internal view of a section of the conduit of FIG. 4A near a set of flanges, which are provided with a bent plate attached to the flange insert to provide disturbance and mixing in the conduit. FIG. 4D is an internal view of a section of the conduit of FIG. 4A near a set of flanges, which are provided with a ventury type attachment to the flange insert to provide disturbance and mixing in the spiral. FIG. 4E is an end view of the insert of FIG. 4B not drawn to scale. While FIGs. 4B to 4D make reference to FIG. 4A which uses a spiral conduit, these three Figures (B to D) may also represent the use of obstructions in a conduit that is in the form of a coil.
FIG. 5 is side view of a hydrocyclone with a conduit in the form of a spiral and an open vessel with an overflow outlet at the bottom feeding the agglomerating drum of an oleophilic apertured wall separator to remove air, water, solids from the hydrocyclone overflow. It is of note to mention that for the sake of convention, the bottom and top of a hydrocyclone are described here as though the open vessel is mounted in an upright position.
However, the hydrocyclones of the present invention may be mounted in any direction, vertical, horizontal or at an angle, since the centrifugal force field in the hydrocyclones of the present invention normally is much larger than the force field due to gravity.
FIG. 6 is a flow diagram of an apertured oleophilic wall separator operatively connected with the helical conduit of a hydrocyclone of the present invention to recover bitumen from sludge by the separator followed by a preliminary bitumen product clean up by the hydrocyclone system.
FIG. 7 is a flow diagram of two hydrocyclones in series.

Jan Kruyer, Thorsby, Alberta, Canada It will be understood that the above figures are simplified and are merely for illustrative purposes in furthering an understanding of the invention without in any way limiting any applications or aspects of the invention. Further, the figures are not drawn to scale, thus dimensions and other aspects may, and generally are, exaggerated or changed to make illustrations thereof clearer. Therefore, departure can be made from the specific dimensions and aspects shown in the figures in order to produce the hydrocyclones of the present invention.

DETAILED DESCRIPTION
Before the present invention is disclosed and described, it is to be understood that this invention is not limited to the particular structures, process steps, or materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.
It must be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a pump" includes one or more of such pumps, reference to "an elbow" includes reference to one or more of such elbows, and reference to "injecting" includes reference to one or more of such actions.
DEFINITIONS:
In describing and claiming the present invention, the following terminology will be use herein in accordance with the definitions set forth below.
Aerated refers to containing gas. An aerated froth is a froth that contains gas which gas may be air or any other type of gas suitable for achieving the objectives of the present invention.
Agglomerator or agglomeration drum refers to a revolving drum containing oleophilic surfaces that is used to increase the particle size of bitumen in an aqueous suspension prior to separation. Bitumen particles flowing through the drum come in contact Jan Kruyer, Thorsby, Alberta, Canada with the oleophilic surfaces and adhere thereto to form a layer of bitumen of increasing thickness until the layer becomes so large that shear from the flowing suspension and from the revolution of the drum, and of the bed of balls, causes a portion of the bitumen layer to slough off, resulting in bitumen particles that are much larger than the original bitumen particles of the slurry.
Apertured refers to a wall that has one or more apertures depending on the function of the aperture or apertures. For example, an apertured aggomerator cylindrical wall has a multitude of apertures to allow the flow of bitumen or tailings. On the other hand, an apertured helical conduit may only have one or more apertures passing through the conduit wall when one or more nozzles are mounted in the helical conduit for injecting of a fluid into the suspension flowing through the conduit. In both cases, the drum wall and the conduit are apertured, since each wall has at least one aperture passing through the wall.
Bitumen refers to a viscous hydrocarbon, including maltenes and asphaltenes, that is found in oil sands ore interstitially between the sand grains. In a typical oil sands plant, there are many different streams that may contain bitumen. Bitumen may also refer to any heavy viscous hydrocarbon. As the result of processing, bitumen may be suspended in water in the presence of particulate solids. Bitumen normally has a specific gravity close to 1.0 but may be denser when it contains captured solid particulates in the bitumen phase particles.
Central location refers to a location that is not at the periphery, introductory, or exit areas. In the case of a pipe, a central location is a location that is neither at the beginning of the pipe nor the end point of the pipe and is sufficiently remote from either end to achieve a desired effect, e.g. washing, reacting with or disrupting agglomerated materials, etc.
Centrifugal force field refers to a force field that is generated inside a helical conduit or inside a hydrocyclone open vessel due to a suspension in the conduit or in the vessel flowing in a helical or circular path.
Conditioning in reference to mined oil sand is consistent with conventional usage and refers to mixing a mined oil sand with water, air and caustic soda to produce a warm or hot slurry of oversize material, coarse sand, silt, clay and aerated bitumen suitable for recovering bitumen froth from said slurry by means of froth flotation. Such mixing can be Jan Kruyer, Thorsby, Alberta, Canada done in a conditioning drum or tumbler or, alternatively the mixing can be done as it enters into a slurry pipeline and/or while in transport in the slurry pipeline.
Conditioning aerates the bitumen for subsequent recovery in separation vessels, e.g. by flotation.
Likewise, referring to a composition as "conditioned" indicates that the composition has been subjected to conditioning.
Conduit refers to a pipe, a tube or a hose that confines an aqueous suspension, which suspension may flow due to a pressure difference between inlet an outlet of the conduit. A
helical conduit is a pipe, a tube or a hose that is formed into the shape of a coil or in the shape of a spiral.
Confined, or confines, refers to a state of substantial enclosure. A path of suspension may be confined if the path is, e.g., walled or blocked on a plurality of sides, such that there is an inlet and an outlet and a direction of the flow which is determined by the shape and direction of the confining material. Although typically provided by a pipe, tube, hose or baffles, other features can also create a confined path.
Cylindrical indicates a generally elongated shape having a substantially circular cross-section. Therefore, cylindrical includes cylinders, conical shapes, and combinations thereof. The elongated shape has a length referred herein to as a depth calculated from one of two points - the open vessel inlet, or the defined top or side wall nearest the open vessel inlet.
Disengagement and digesting of an oil sand ore or slurry are used interchangeably, and refer to a primarily physical separation of bitumen from sand or other particulates in mined oil sand slurry. Disengagement of bitumen from oil sands occurs when physical forces acting on the oil sand slurry results in the at least partial segregation of bitumen from sand particles in an aqueous medium and may not necessarily require a process aid.
Endless cable belt when used in reference to separations processing refers to an endless cable that is wrapped around two or more drums and/or rollers a multitude of times to form an endless belt having spaced cables. Movement of the endless cable belt can be facilitated by at least two guide rollers or guides that prevent the cable from rolling off an edge of the drum or roller and guide the cable back onto a drum or roller. The apertures in Jan Kruyer, Thorsby, Alberta, Canada the endless belt are the slits or gaps between sequential wraps. The endless cable can be a wire rope, a plastic rope, a metal cable, a single wire, compound filament or a monofilament which is spliced together to form a continuous loop, e.g. by splicing. As a general guideline, the diameter of the endless cable can be as large as 2 cm and as small as 0.001 cm, although other sizes might be suitable for some applications. An oleophilic endless cable belt is an endless cable belt made from a material that is oleophilic under the conditions at which it operates.
Fines refers to suspension particles that are not larger than 45 microns on average.
Fines normally pass through a mesh screen that has 45 micron square openings.
Fluid in these specifications specifically refers to a liquid or a gas or to liquid and gas mixtures injected through nozzles or through apertured conduit sections directly through the conduit wall into the flowing suspension.
Fluid tailings are aqueous suspensions representing tailings from an oil sands plant from which coarse solids, such as sand, have been removed. The term fine tailings has replaced the old term of tailings pond sludge but has the same meaning as fluid tailings.
Because of the confusion of terms used for oil sand tailings in the oil sands industry, for the present invention, fluid tailings sludge is a name used for sludge or for fluid tailings. See "sludge" for further clarification.
Helical conduit or conduit refers to a conduit, pipe, tube or hose formed into a spiral or a coil shape including multiple generally circular loops. Consistent with this definition, a "helical path" is a path which follows a helical shape and is generally "confined" to such a path by physical barriers such as pipe walls. Such helical shape can include a coil shape, wherein the shape mostly represents a stretched spring. Alternatively, the helical shape can include a planar helical shape, known as a spiral, wherein the path may be (but does not have to be) in a single plane and is a curve which emanates from a central point, getting progressively farther away as it revolves around the point, such as the spiral conduit shown in FIG. 2B. In terms of flow path, the flow gets progressively closer to the central point in such spiral embodiments.
Hydrocyclone may at times be used interchangeably with "separating apparatus,"

Jan Kruyer, Thorsby, Alberta, Canada where both terms indicate the equipment, as described herein, beginning with the helical conduit and including the open vessel with an underflow and an overflow.
Open vessel or drum of a hydrocyclone refers to a vessel which is substantially free of internal structures and/or obstructions other than those explicitly identified as present, e.g.
a vortex finder. An open vessel, as used herein, can often be a completely vacant cylindrical vessel having various inlets and outlets as identified, with substantially no other structures present within the vessel other than a vortex finder.
Operatively associated with refers to any functional association which allows the identified components to function consistent with their intended purpose. For example, units such as pumps, pipes, vessels, tanks, etc. can be operatively associated by direct connection to one another or via an intermediate connection such as a pipe or other member. Typically, in the context of the present invention, the units or other members can be operatively associated by fluid communication amongst two or more units or devices. The term "operatively connected to" has a similar meaning but it is more specific. For example when a conduit is operatively connected to an open vessel inlet it implies that the outlet of the conduit is connected to the inlet of the open vessel smoothly so as to optimize the operation of the conduit and to optimize the operation of the open vessel. Similarly, when an overflow outlet is operatively connected to a vortex finder it implies that the connection between vortex finder and outlet is such as to optimize the operation of the vortex finder and to optimize the operation of the overflow outlet.
Overflow refers to a more central portion of a swirl flow, and as such, is often the more valuable fluid containing fines and bitumen, and/or valuable minerals.
Alternately the overflow may consist of gangue.
Series represents a number of more than two. A series of nozzles, for example, can be three nozzles, four nozzles, five nozzles, etc. The series of nozzles can be regularly placed or irregularly placed, with respect to distance between nozzles.
Sludge is the generic name used in the present invention for any fluid tailings suspension that has resided for any time in a mined oil sands tailings pond.
Sludge includes fresh fine tailings that may have just arrived in the pond, fine tailings that have resided in the Jan Kruyer, Thorsby, Alberta, Canada pond for over a year, and mature fine tailings that have resided in the pond for one or several decades. The main difference between fresh fine tailings and fine tailings is that fine tailings have a lower water content than fresh fine tailings. Similarly, mature fine tailings have a lower water content than fine tailings. Besides sludge giving up water with time in the pond, microbial action in sludge occurs when the sludge matures or ages in the pond.
Such microbial action results in the formation of gases and changes in the bitumen chemistry of the sludge. Fresh fine tailings may also be tailings from which coarse solids, such as sand, have been removed but which have not entered a tailings pond.
Swirl path refers to a flow pattern inside an open vessel or drum which generally follows an unconfined helical path, although significant mixing and chaotic flow may occur along the axis of overall flow down the length of the vessel or drum. A swirl path is generally produced by introducing fluids tangentially into a generally cylindrical vessel thus producing flow circumferentially as well as longitudinally down the vessel length. A swirl path refers to an unconfined, generally helical, swirl flow inside an open vessel.
Underflow refers to a more circumferential portion of a swirl flow and typically contains coarser material and is often drawn off as effluent and/or for further processing. In many cases the underflow contains predominantly hydrophilic particulates in water. Often, a fluid processed by a hydrocyclone is split into a single overflow and single underflow, although multiple overflow and/or underflows may be issue when hydrocyclones are placed in series.
Velocity is used consistent with a physics-based definition; specifically, velocity is speed having a particular direction. As such, the magnitude of velocity is speed. Velocity further includes a direction. When the velocity component is said to alter, that indicates that the bulk directional vector of velocity acting on an object in the fluid stream (liquid particle, solid particle, etc.) is not constant. Spiraling or helical flow patterns are specifically defined to have substantially constant or gradually changing bulk directional velocity.
Vortex finder refers to a centrally located pipe within a hydrocyclone open vessel for the purpose of removing overflow from the hydrocyclone. The vortex finder can be a simple pipe having an unrestricted open pipe entrance and, alternately may be provided with Jan Kruyer, Thorsby, Alberta, Canada a flange at the pipe entrance as well, to encourage overflow to find its way from the open vessel hydrocyclone interior into the vortex finder opening. A vortex finder normally is operatively connected to an overflow outlet of the open vessel.
Substantially refers to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result. For example, an object that is "substantially" enclosed would mean that the object is either completely enclosed or nearly completely enclosed. The exact allowable degree of deviation from absolute completeness may in some cases depend on the specific context. However, generally speaking the nearness of completion will be so as to have the same overall result as if absolute and total completion were obtained. The use of "substantially" is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result.

A plurality of components may be presented in a common list for convenience.
However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary.
Concentrations, amounts, volumes, and other numerical data maybe expressed or presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and thus should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. As an illustration, a numerical range of "about 1 cm to about 5 cm" should be interpreted to include not only the explicitly recited values of about 1 cm to about 5 cm, but also include individual values and sub-ranges within the indicated range. Thus, included in this numerical range are individual values such as 2, 3, and 4 and sub-ranges such as from 1-3, from 2-4, and from 3-5, etc. This same principle applies to ranges reciting only one numerical value. Furthermore, such an interpretation should apply regardless of the breadth of the range or the characteristics being described.

Jan Kruyer, Thorsby, Alberta, Canada Consistent with this principle the term "about" further includes "exactly"
unless otherwise stated.

EMBODIMENTS OF THE INVENTION

It has been found that fluids having components of different densities, of different surface chemistry and/or containing different particle sizes, particularly those including mineral particulates and liquid, can be effectively separated using a hydrocyclone having a helical conduit immediately upstream of a substantially cylindrical open vessel.
Hydrocyclones can be used as a separating mechanism for a variety of suspensions.
However, the hydrocyclones of the present invention can be particularly suited to the replacement of conventional gravity induced froth flotation for the separation of liquid suspensions by imposing a much greater separation force on the suspension than is possible by gravity alone. Not only can the imposed separation force field in a hydrocyclone be much greater than is possible with conventional gravity induced froth flotation, but the use of a helical conduit ahead of the hydrocyclone drum also allows for the introduction of various fluids, through the conduit wall, including gasses, activators, promoters, suppressants, frothers and other chemicals into the suspension while the flowing suspension is exposed to a centrifugal force field that is much greater than the force of gravity alone.
The suspension flowing through the helical conduit is exposed to a centrifugal force field and also is confined in the conduit under pressure which pressure gradually decreases as the suspension flows through the conduit from entrance to exit before it enters the hydrocyclone open vessel through its entrance to become part of the swirl region within the hydrocyclone open vessel to be subsequently separated into an underflow stream and an overflow stream.
In accordance with the above discussion, various embodiments and variations are provided herein which are applicable to each of the apparatus, fluid flow patterns, and methods of separating components of a suspension described herein. Thus, discussion of one specific embodiment is related to and provides support for this discussion in the context of Jan Kruyer, Thorsby, Alberta, Canada the other related embodiments.
As a general outline, a hydrocyclone can include a substantially open cylindrical vessel with an open vessel inlet. The open vessel inlet can be configured to introduce a fluid tangentially into the open vessel. In a specific embodiment, the open vessel inlet connecting the helical conduit to the open vessel can be configured to introduce the fluid into the open vessel with minimal disturbance in fluid flow in the transition between the conduit and the open vessel. Thus the hydrocyclone can include a helical conduit connected upstream of the open vessel at the open vessel inlet. An overflow outlet and an underflow outlet can be operatively attached to the open vessel wall. The underflow outlet can be attached at a location on the open vessel substantially opposite the helical conduit and open vessel inlet.
The overflow outlet can terminate, on one end, at a vortex finder positioned in an interior of the open cylindrical vessel. The overflow outlet can further include a substantially enclosed conduit from the vortex finder to an exterior outlet of the open cylindrical vessel.
Several embodiments of a hydrocyclone in accordance with the present invention including a helical conduit in the form of a coil are shown in FIGs. 1 A to FIG. 1 E including a helical path 100 connected to a substantially open cylindrical vessel 101 at an open vessel inlet 102. The embodiments further include underflow outlets 103 attached to the open vessel substantially opposite the helical conduit 100. The underflow outlets 103 illustrated are oriented to match the residual helical flow within the open vessel to facilitate removal of underflow fluids. In the case of FIG. IA the open vessel bottom 104 is conical and the underflow suspension leaves axially through the bottom 105 of the conical part 104 of the open vessel. In the case of FIG. 1C, the open vessel bottom 106 also is conical but the underflow suspension leaves tangentially through an outlet 107 of the bottom of the conical part of the open vessel. In the case of the case of FIG. I E, the underflow leaves tangentially through a bottom outlet 108 of the open vessel that does not have a conical bottom section but remains of a generally constant diameter. The external overflow outlets illustrated are operatively connected to internal vortex finders inside the open vessel. In the case of FIGs.
1 A,1 B,1 C and 1 D the vortex finders 112 and 113 are operatively connected to overflow outlets 109 and 110 attached to the top of the open vessels 101 concentric with the conduit Jan Kruyer, Thorsby, Alberta, Canada 100. In FIGs. I E and I F the vortex finder 114 is operatively connected to an overflow outlet 111 attached to the bottom of the open vessel 101. The vortex finders 112, 113 and 114 can be positioned centrally (axially) within the open vessels 101 and can be further positioned at a depth that is central or such depth can be adjusted based on the particular suspension velocity, composition and other variables to maximize separation of the suspension into a suitable underflow and a suitable overflow. Although not always required, as can be seen in FIGs. IA to IF, outer diameters of the helical conduit 100 and the open vessel 101 are substantially the same, at least where these two members are joined. FIGs. IA
to IF also illustrate the inlets 116, 117 and 118 where the suspension to be separated can be fed into the inlet of the helical conduits of the hydrocyclones. Further, the Figures schematically show fluid inlets or nozzles 120 which allow the injection of fluids into the conduits to further enhance subsequent separation of the suspension in a centrifugal force field.
The fluid inlets 120 may be configured to inject fluid perpendicularly into the path of the suspension flowing through the conduit or may be directed for tangential injection of fluid into the suspension or alternately may be directed at an angle for injection of fluid into the suspension with or against the direction of flow of the suspension to allow the desired mixing of fluid with suspension.
The helical conduit situated upstream of the open vessel can serve at least three purposes. First, it can be configured to cause a suspension to at least partially separate, or begin the separation process prior to entering the open vessel. Second, the helical conduit can cause suspension to travel in a path that encourages further separation and easier transition once introduced into the open vessel. Third, fluid injected into the supension along the periphery of the helical conduit can react with the surfaces of the particulates in the suspension and activate, promote or suppress the hydrophobicity of these particles and cause separation of these particles by froth flotation in a centrifugal force field that is more effective and faster than froth flotation in a conventional flotation cell. As such, parameters such as the size and configuration of the helical conduit, the direction and location of fluid injection points along the helical conduit, the dimensions of the open vessel, and the open vessel inlet can affect processing. The number of rotations of the helical conduit can, for Jan Kruyer, Thorsby, Alberta, Canada some fluids, allow for a shorter or longer time spent in the open vessel to produce the same level of separation. In a specific embodiment, the helical conduit can wind for about 2 to about 10 full rotations. In a further embodiment, the helical conduit can wind for about 3 to about 5 full rotations.
The helical conduit can also be formed in a variety of ways from pipe, from tube or from hose, and the tube may be circular in cross section or may have a square or rectangular cross section. Other types of conduits may be used as well. For example, complementary structural channels may be rolled to the desired curvature and welded together to form conduits of square or rectangular cross section, described in more detail in copending Canadian patent application entitled "Hydrocyclone and Associated Methods ".
The inlet to the helical conduit is at one end of the helical conduit and is the primary source of introducing the suspension into the hydrocyclone of the present invention. The suspension travels through the helical conduit and leaves from the conduit to flow into the open vessel through the open vessel inlet. Components of the fluid are separated and removed through the underflow outlet and through the overflow outlet of the open vessel.
As mentioned previously, the fluid injected through conduit wall into the suspension flowing in the conduit can include liquids containing or consisting of chemicals commonly classified as activators, promoters, frothers or suppressants, or may include a gas, a hydrocarbon or may also include a mixture of steam and air or a mixture of compressed gas dissolved in water under pressure. In most cases the fluid injected through the conduit wall is at a higher pressure than the suspension flowing through the conduit in the fluid injection region. After injection into the suspension, gasses dissolved in the injected fluid will come out of solution in the form of gas bubbles when this fluid mixes with the suspension in the conduit, and these gas bubbles will expand in size as the suspension pressure decreases down the conduit on its way to the hydrocyclone open vessel. In some cases, two or more chemicals may be injected as fluids through separate nozzles or through separate porous sections of the conduit wall into the suspension, which chemicals may react with each other upon contact to achieve the objective of the present invention to promote froth flotation in a centrifugal force field. For example two fluids combining may result in a desired chemical reaction or may form gas bubbles in the suspension to which hydrophobic particles (including bitumen if present) may attach to enhance froth flotation in the present invention. As another example, milk of lime Jan Kruyer, Thorsby, Alberta, Canada may be the injected fluid which may react with the contents of the suspension flowing through the conduit. In this case both the liquid in the conduit and the injected fluid are suspensions of solid particulates in water. A similar fluid may be a suspension of gypsum in water. Using suspensions of this nature as the fluid may allow for faster chemical reactions in the conduit than using dissolved lime or dissolved gypsum in water only, since water can only hold a small amount of dissolved lime or gypsum.
The use of a conduit in the form of a spiral is illustrated in FIG. 2. A side view is shown in FIG. 2A and a plan view is shown in FIG. 2B. A suspension under pressure flows from a feed pipe 201 into the inlet 202 of the spiral. The feed pipe may be connected to the spiral conduit 204 by means of flanges 203 or by some other means, such as, for example, by welding. Nozzles 205 are mounted into the wall of the spiral conduit to allow for injection of fluid into the suspension as it travels through the conduit 204. The spiral conduit connects smoothly to the open vessel 208 of the hydrocyclone and, as a result, the suspension leaves the conduit 204 and enters the open vessel 208 with a minimum amount of flow disturbance to continue the flow and become a swirl path in the open vessel until the suspension splits into two streams, the overflow, and the underflow. Overflow outlet 207 and underflow outlet 206 are shown in FIGs. 2A and 2B. The overflow outlet 207 is operatively connected to a vortex finder 210 inside the open vessel 208.
FIG. 2C is an internal view of a section of the spiral conduit 204, showing an inside lane 215 and an outside lane 216. It also provides an illustration of the contents of the suspension in the conduit 204 where coarse un-aerated particulates gravitate towards the outside lane and aerated particles gravitate towards the inside lane. This is the result of the centrifugal force field in the conduit and of gas bubbles injected as the fluid 220. The hydrophobic (oleophilic) particles adhere to the gas bubbles and cause these particles to gravitate towards the inner lane under the influence of the centrifugal force field operating in the flowing suspension in the conduit. In FIG. 2C the gas bubbles are illustrated in the form of open circles to which are attached small black particles, indicating bitumen droplets or hydrophobic mineral particles. In the enclosed Figures nozzles are used to illustrate the flow of fluid through conduit walls. However porous or aperture wall sections in the conduit in some cases may serve the same purpose, or a more effective purpose than nozzles in some Jan Kruyer, Thorsby, Alberta, Canada cases.
All this is in contrast with the above referenced copending US patent application "Removal of Bitumen from Slurry Using a Scavenging gas ", filed June 3, 2008, in which the amount of gas injected into the conduit was kept at a minimum in an effort to minimize or eliminate the production of froth from the hydrocyclone overflow. It was the objective of that copending application to allow the bulk of the suspension to absorb the injected gas before the overflow left the hydrocyclone open vessel. The present invention has the opposite objective of adding an abundance of gas to the suspension in the conduit and to produce an overflow from the hydrocyclone that contains an abundance of froth.
Hence, FIG. 4 of the copending referenced US patent application shows a much smaller number of gas bubbles in the suspension flowing through the conduit, as compared with the much larger number of gas bubbles in the suspension flowing through the conduit of FIG. 2C
of the current patent application. The gas bubbles in the Figure are illustrated by open circles and most of the bubbles have a hydrophobic particle attached to them, illustrated in the form of black dots.
For a suspension containing solids that have a higher density than the suspension liquid, the centrifugal force field in the suspension flowing through the helical conduit causes the gradual movement of solids towards the outer lane with minimal disturbance of the flowing suspension. Furthermore, for a constant suspension flow rate, the centrifugal force field in a conduit in the form of a coil tends to be constant. In contrast, for a constant suspension flow rate, the centrifugal force field gradually increases as the suspension travels in a conduit that has a progressively increasing curvature between conduit inlet and open vessel inlet, such as in a spiral. In a spiral conduit, the coarse and heavy solids initially move to the outside lane, when the centrifugal forces are relatively small, Then gradually, as the centrifugal force field increases, this layer of solids increases in thickness as the smaller and lighter solids progressively move towards the outer lane and deposit on top of and fill the voids between the coarse solids. In this manner, a relatively smooth transitional sorting of the solids takes place while the slurry is flowing through a helical conduit in the form of a spiral. After the suspension enters the open vessel through a low disturbance entrance, the Jan Kruyer, Thorsby, Alberta, Canada bed of coarse solids can continue to flow along the outer periphery of the open vessel in the form of a swirl path and report to the underflow while the coarse-solids-depleted suspension reports to the overflow and contains all, or nearly all the froth and a portion of the fines of the suspension.
It is well known that in centrifuges there are very high shear forces that exist at the point where the suspension enters the bowl via the axial feed and is accelerated to the bowl speed. Similar shear forces, although perhaps to a lesser extent, occur near the tangential inlet of conventional hydrocyclones where the linearly moving suspension is rapidly converted into a suspension moving in a helical flow path. Such a drastic conversion does not occur in the hydrocyclones of the present invention since a helical flow path is already well established in the conduit before the suspension enters the open vessel.
The nozzles or porous conduit wall sections that supply fluid to the helical conduit serve to, for example, introduce an abundance of gas bubbles that aerate bitumen of the suspension flowing through the conduit and that also scavenge bitumen droplets and/or hydrophobic solids out of the voids in the bed of solids flowing along the outside lane of the conduit and thereby help in transferring these to the suspension stream in the middle or inside lane of the conduit, the bulk of which may leave the hydrocyclone through the overflow. While this discussion mainly centered around the benefits of a helical conduit in the form of a spiral, a similar frothing of bitumen and/or hydrophobic solids and a similar transfer of captured bitumen droplets and/or hydrophobic minerals to the middle and inside lane of the suspension stream takes place with the help of gas bubbles if these are introduced in a helical conduit that has the form of a coil.
The nozzles can be present in a series along the length of the helical coil.
The series can be regularly or irregularly spaced. Typically, a nozzle can be mounted at a location along the outer wall of the helical conduit, but it may also be mounted along the inner wall or along any other position of the cross section of the conduit. A variety of nozzles can be used in the design of the separating apparatus. In one aspect, the series of nozzles can be designed for sonic gas flow through the nozzles, where each nozzle is configured to produce local cavitation and gas dispersion upon the gas entry into the helical conduit. In another aspect Jan Kruyer, Thorsby, Alberta, Canada the fluid may be a liquid containing compressed gas that releases from the fluid after entry into the suspension. In yet another aspect the fluid may be a froth flotation collector, activator, depressant, frother or modifier, which are common or special chemicals used in conventional froth flotation of minerals. In some cases porous sections for fluid injection may be mounted between flanges in the helical conduit. Such flange mounting facilitates surrounding a porous section with a pressure chamber for containing fluid to be injected into the conduit but also provides for convenient replacement or for cleaning Gas bubbles injected into the conduit may be of various sizes depending on a large number of variables, including nozzle design and size, aperture size of porous conduit sections, pressure difference between injected fluid and suspension in the conduit, etc. Small size gas bubbles are preferred for these have a lower tendency to coalesce. A
high concentration of very small bubbles sweeping through the suspension will tend to capture bitumen or hydrophobic minerals and may dislodge bitumen and/or hydrophobic minerals from between coarse hydrophilic solids in the outer lane. Generally, bubbles can have diameters smaller than about 3 mm, although bubbles having a diameter smaller than about 0.3 mm or even smaller than 0.03 mm can be particularly useful in achieving increased contact surface area with bitumen and/or hydrophobic minerals of very small particle size.
One very effective way of producing very small gas bubbles is the use of a injection fluid consisting of a mixture of compressed air and steam. Another method of producing very small and well dispersed bubbles is to prepare a fluid, such as a water and gas mixture under high pressure in a vessel which is then allowed to flow through the conduit wall into the suspension. Under high pressure, gasses such as air, air enriched by oxygen, methane, ethane, propane, carbon dioxide, or combinations thereof may be dissolved in large quantities in liquid, such for example water, under high pressure. When such high pressure liquid and dissolved gasses flow through the conduit wall of the instant invention and encounter a suspension of lower pressure in the helical conduit, the gasses may be released in the form of small bubbles. Many small bubbles of gas released very quickly in the suspension may sweep through the voids between the solids in suspension and may also transport trapped bitumen and/or hydrophobic solids out of the voids between coarse Jan Kruyer, Thorsby, Alberta, Canada hydrophilic solids flowing along the outside lane of the conduit. Since there is a pressure gradient in the suspension flowing through the conduit, small gas bubbles near the entrance of the conduit will increase in size as these flow through the conduit, enter the open vessel and leave as overflow.
Therefore, as outlined above, the instant invention can function to aerate hydrophobic particles, including valuable minerals or other minerals or bitumen and also to transfer such hydrophobic particles from the outside lane of the conduit into the centre or inside lane of the conduit to optimize the subsequent content of these hydrophobic particulates in the overflow of the hydrocyclone. In another embodiment of the instant invention, additives, such as collectors, activators, depressants frothers, gas and/or flotation modifiers may be introduced through the conduit wall into the suspension flowing through the helical conduit to promote the desired separation of hydrophobic particulates from hydrophilic particulates by the hydrocyclones of the present invention. In some cases these additives may serve to selectively make some particulates hydrophilic and selectively make other particulates hydrophobic and promote adhesion of these hydrophobic particles to gas bubbles. In fact, the same surface chemistry and surface adhesion technology that was developed for convention gravity induced froth flotation may be applied to the methods of the present invention that uses froth flotation under the influence of a centrifugal force field. Hydrophobic mineral particles, which particles may include bitumen particles in some cases, that adhere to gas bubbles are lighter than mineral particles without gas bubbles and will rise through a suspension to the top of a conventional flotation vessel. Similarly, in a flowing suspension in a helical conduit, hydrophobic particles that adhere to gas bubbles are lighter than mineral particles without gas bubbles and may gravitate towards the inside lane of the conduit due to the centrifugal force field operating in the curved conduit. These density reduced particles will flow through the open vessel swirl path and may report to the overflow, while coarse and dense hydrophilic particles generally will leave the hydrocyclone through the underflow.
Gas that may be used as the fluid under pressure flowing through the conduit wall into the suspension may contain air,oxygen enriched air,a light hydrocarbon gas, such as methane, ethane, propane, butane, carbon dioxide, or any combination thereof. The use of carbon dioxide may also serve to neutralize an oil sand slurry if it has a pH greater than 7 as the carbon dioxide is consumed in the suspension producing sodium carbonate or sodium bicarbonate by reaction with sodium hydroxide that may be present in, for example an oil sand slurry Aqueous reagents that may be injected through the conduit wall may also include Jan Kruyer, Thorsby, Alberta, Canada anionioc collectors, alkyl sulfonates and sulfates, cationic collectors, amphoteric collectors, chelating agents, sodium sesquicarbonate, ammonium lignin sulfonate, corn starch, potato starch, high molecular weight water soluble gums, portland cement,amine-aldehyde resins, soda ash, sodum silicate, alkali phosphate, dextrin, polyhydroxy amines, hot lime, slaked lime, milk of lime and aqueous suspensions of finely divided gypsum, Optionally, one or more nozzle may be mounted in the wall of the open vessel.
Such nozzles can be configured to inject a gas, a liquid including dissolved gas, or even a conventional froth flotation additive into the swirl path in the open vessel.
The helical conduit situated upstream of the open vessel can be configured to cause a fluid to at least partially separate, or begin the separation process prior to entering the open vessel. Additionally, the helical conduit can cause the fluid to travel in a path that encourages further separation and easier transition once introduced into the open vessel. As such, parameters such as the size and configuration of the helical conduit, the number and location of nozzles or porous conduit sections, the dimensions of the open vessel, and the open vessel inlet can affect processing. The number of rotations of the helical conduit can, for some fluids, allow for a shorter or longer time spent in the open vessel to produce the same level of separation. In a specific embodiment, the helical conduit can wind for about I
to about 10 full rotations. In a further embodiment, the helical conduit can wind for about 2 to about 5 full rotations.
The open vessel inlet, which allows flow from the conduit into the open cylindrical vessel, can be configured to introduce the fluid with minimal disturbance in the fluid flow.
For example, the internal surfaces at the connection between the helical flow conduit and the open vessel can be a substantially smooth transition where the inside surface of the helical conduit smoothly blends into the inside surface of the open vessel. The confined fluid exiting the helical conduit may flow smoothly into the open vessel to form the swirl path that eventually separates into an underflow and an overflow. Minimal disturbance in the fluid flow from the helical conduit to the open vessel allows for greater separation efficiency.
This configuration further reduces abrasive wear on internal surfaces of the open vessel. In particular, initiating the centrifugal force field well ahead of the open vessel can significantly reduce wear and abrasion of the open vessel internal walls. The slower flowing bed of solids Jan Kruyer, Thorsby, Alberta, Canada flowing along the outer wall of the helical conduit will join the open vessel swirl path at a slower rate than non-peripheral flow of the suspension. This aspect of the present invention provides wear reduction as compared with direct tangential introduction of a suspension into an open vessel where the swirl path is established only after the slurry enters the open vessel.
To aid in fluid flow, in one embodiment, a pump or a plurality of pumps can be used.
This is particularly useful at the beginning of the helical conduit to cause the fluid to flow at a desired velocity which is generally relatively high. Normally a pipe or pipeline may provide the suspension to the helical conduit, but pumps can optionally be additionally used.
However, care in design should be taken in order to prevent or reduce undesirable disturbance to flow patterns in suspension entering the open vessel.
In a specific embodiment, a method for separating components from a fluid can include guiding the fluid through a helical conduit at a high velocity to form a helically flowing fluid. The method can further include tangentially injecting the helically flowing fluid into an open vessel such that the fluid rotates along a swirl path within the open vessel.
The fluid rotation in the swirl path, and enhanced by rotation in the helical conduit, can be sufficient to produce an overflow and an underflow. Such fluid separation is based on the varying densities and varying particle sizes of the components of the fluid.
The method can additionally include injecting a fluid through walls into at least one of the helical path and the swirl path. The overflow and underflow can be removed from the open vessel.
The fluid in the helical conduit can travel at any velocity sufficient to produce an initial separation of the fluid components while in the helical conduit and/or produce an overflow and underflow while in the open vessel. Such initial separation can include compositional differences across a diameter of flow. Although such velocity will vary depending on the design of the hydrocyclone and the fluid to be processed, in one embodiment, the magnitude of the velocity of the suspension in the helical path can be from about 1 meter per second to about 10 meters per second, and in some cases from about 2 meters per second to about 4 meters per second.
In a specific embodiment, fluid can be injected into the helical conduit substantially prior to the tangentially injecting into the open vessel. For example, fluid can be injected Jan Kruyer, Thorsby, Alberta, Canada through the wall of the helical conduit at a central location along the helical conduit between a fluid inlet to the helical conduit and the open vessel inlet. Such injection along the helical conduit can include injection of one or more fluids at a plurality of locations along the helical path. Nozzles may alternate with apertured conduit sections or nozzles or apertured sections may be used exclusively. Alternative to, or in conjunction with injecting fluid through the walls of a helical conduit, fluid of the same or different type, can be injected into the swirl path. Such injection of fluid into the swirl path can be substantially subsequent to injecting fluid through the conduit wall. For example, the fluid can be injected at central locations to the open vessel inlet and the underflow outlet. As with injecting fluid into the helical conduit, fluid can be injected into the swirl path at a plurality of locations through nozzles.
The overflow and underflow will generally contain particulates but will have different compositions. When processing an oil sand suspension, the overflow will contain, ideally, water and bitumen froth and silt and clay particulates which are small and possibly of lower density. The underflow, on the other hand, will ideally contain water, silt, sand, and particulates which are larger and may also be denser. When processing a minerals ore mixture, the suspension to be separated can be an aqueous suspension containing particulates. In such case, and depending on the other components in the suspension, the underflow can include particulates that naturally are hydrophilic or the surfaces of these particulates may have been made hydrophilic by the use of one or more suppressors or suppressants injected as a fluid into the helical conduit. Similarly the overflow may include a froth of particulates that are naturally hydrophobic, or the surfaces of these particulates may have been made hydrophobic by the use of activators, collectors or modifiers injected as a fluid into the helical conduit. In addition, gas may have been part of the injected fluid to cause the hydrophobic particles to adhere to gas bubbles to lighten them and cause them to first move away from the outer lane of the conduit fluid and subsquently report to the overflow of the hydrocyclone in the form of froth. The hydrocyclones of the present invention are particularly suited to separation of an oil sand suspension or a bitumen containing suspension representing a continuous water phase containing dispersed bitumen particulates or agglomerates, gravel, sand, silt and clay or a water suspension of dispersed Jan Kruyer, Thorsby, Alberta, Canada bitumen product and fines. Alternatively, mineral ore slurries can be effectively separated using the hydrocyclones described herein. Among others, the fluid injected through the wall of the conduit may be air, gas, a liquid containing dissolved gas, a mixture of air and steam or may be a suspension in water, such as milk of lime or a suspension of gypsum dispersed in water, or similar dispersions in water of divalent or trivalent salts, etc.
One specific use of the hydrocyclone can be in de-sanding fluids containing bitumen.
In such case, the fluid can include particulates, bitumen, air and water.
Particulates included in the bitumen-containing fluid can include gravel, sand, and fines. When processed, the overflow can include the majority of the bitumen of the fluid in the form of froth and the underflow can include the majority of the gravel and sand. In a specific embodiment, the overflow can include less than 20% of the particulates in the form of fine sand and fines.
Unlike the above referenced copending patent application first filed less than 12 months ago, the amount of gas introduced into the helical conduit of the present invention is large enough that the overflow contains a high percentage of froth. This is unlike the referenced copending application where the objective was to minimize the amount of gas added and thus reduce or eliminate the amount of froth reporting to the overflow of the hydrocyclone.
The objective of the prior patent was to produce a bitumen product that was very low in gas content by allowing gas introduced into the helical conduit to be absorbed in the bulk of the suspension fluid of the hydrocyclone before the overflow left the open vessel.
Not all bitumen-containing fluids are the same, and the varying properties of bitumen-containing fluids need to be considered when designing a particular hydrocyclone.
Conditions and/or design of the hydrocyclone can be specifically configured for improved and optimum processing. In a specific embodiment, the helical conduit and/or open vessel can be designed and shaped based on compositional and physical properties of the fluid.
Therefore, parameters may be adjusted for varying types of bitumen-containing fluids.
The bitumen-containing fluid can be a result of pre-conditioning of oil sands and water. As such, the composition of the fluid can, at least partially, depend on the composition of the oil sands. Some oil sands contain a high percentage of bitumen and low percentage of fines, while other oil sands contain a moderate or a small percentage of Jan Kruyer, Thorsby, Alberta, Canada bitumen and further have a high fines content. Some oil sands come from a marine deposit and other oil sands come from a delta deposit, each having different characteristics. Some oil sands are chemically neutral by nature and other oil sands contain salts and other chemicals that affect, among other things, the pH or the salinity of the slurry.
Other factors to consider when dealing with oil sands include the composition of the rocks and gravel, and lumps of clay in the oil sand after crushing. Not only the size of the rocks, gravel and clay lumps but also the percentage of these in the crushed oil sand, as well as the shape of the rocks gravel or lumps of clay can affect processing conditions. Likewise, the chemical composition of the slurry as it is being processed by the hydrocyclone can affect processing. For example, a fluid that has a low pH or a high pH
inherently, or by the addition of chemicals will have a very different rheological characteristic than a suspension that is close to neutral or close to the isoelectric point. The pH of a fluid can have a substantial impact upon the dispersion of fines in such a fluid and upon the resulting viscosity of the fluid. At high or low pH the clay fines are dispersed, resulting in low viscosity fluids in which bitumen particles and the coarse solids are substantially free to move and/or settle within the suspension of the separating vessel.
A factor to consider in selecting processing parameters is the velocity of the fluid as it flows through the hydrocyclone, and through the helical conduit in particular. For a given pump capacity, a different pipe size will result in a different fluid velocity in the hydrocyclone. Therefore, multiple pumps can be used in some embodiments ahead of the conduit (rather than in or after the conduit which would create undesirable disturbance to the flow path).
Processing time for fluids differs greatly depending on the helical conduit, open cylindrical vessel, fluid, desired processing, etc. As a non-limiting example, however, the fluid can have an average residence time in the hydrocyclone, from introduction into the helical conduit, until removal as either underflow or overflow of from about 1 second to about 30 seconds, and in some cases from about 4 seconds to about 10 seconds.
Therefore, as outlined above, the instant invention can function to separate components of suspensions. The fluids injected into the suspensions may be water, flotation Jan Kruyer, Thorsby, Alberta, Canada modifiers, other chemicals dissolved in water, hydrocarbons and gasses, including air, as the froth producing reagent fluids. Additionally, the combination of a helical conduit and open vessel gives greater control over separation and fluid flow than does separation by means of one or the other portions of the hydrocyclone alone.
FIGs. 3A, 3B, and 3C illustrate various possible hydrocyclones of the present invention using a helical conduit 305 in the form of a spiral, each having a suspension entrance 301 and nozzles 313 for the injection of a fluid or fluids onto the conduit 305. Each has an overflow 302 and an underflow 303 connected to an open vessel 312.
Nozzles are illustrated in the drawings to convey that fluid enters through the wall of the conduit.
In the case of FIG. 3A the overflow 302 is at the top of the open vessel 312 and the overflow outlet is operatively connected to an internal vortex finder 304. The underflow 303 leaves the open vessel tangentially near the bottom of the open vessel 312. In this case, a pump 310 is connected to remove the underflow suspension from the open vessel 312 to create a greater pressure drop through the hydrocyclone circuit or to affect adequate underflow velocity for injection into one or more subsequent hydrocyclones or for disposal of underflow through a pipeline. This pump may have a variable speed drive to control the flow of underflow 303 and hence to control the partition of suspension between overflow and underflow for more effective operation of the hydrocyclone open vessel 312 and the helical conduit 305.

In the case of FIG. 3B the overflow 302 leaves through the bottom of the open vessel 312 and is operatively connected to a vortex finder 304 inside the open vessel 312. A
restriction 311 is placed in the underflow 303 outlet to control the partition of suspension between overflow and underflow for more effective operation and control of the hydrocyclone open vessel 312 and the helical conduit 305. In this case, the restriction 311 may be in the form of a variable controlled constriction that controls the desired partition of the hydrocyclone, as to how much of the suspension leaves through the underflow 303 and how much leaves through the overflow 302.
In the case of FIG. 3C the open vessel 312 has a conical bottom 306 and an underflow 303 that leaves through the conical bottom. The overflow 392 leaves through the Jan Kruyer, Thorsby, Alberta, Canada top and is operatively connected to a vortex finder 304 inside the open vessel 312.
FIG. 3D is a graph showing the rise velocity of a bitumen droplet in a commercial oil sand extraction PSV as a function of bitumen droplet diameter when the PSV
suspension contains a fresh oil sand slurry mixed with fresh water. The bottom curve shows the rise velocity of bitumen droplets when caustic soda is not added to the suspension and the top curve shows the rise velocity of bitumen droplets when an optimum amount of caustic soda is added to disperse the suspension and cause optimum bitumen droplet rise velocity. This curve is based on research data published by Laurier L. Schram, a well known Syncrude Canada researcher, in May 1989 in the Journal of Canadian Petroleum Technology. It shows that the addition of caustic soda to the suspension causes an almost 20 fold increase in the droplet rise velocity. However, the commercial addition of caustic soda to oil sand ore results in the accumulation of huge amounts of tailings pond sludge that will not settle in ponds adjacent to commercial mined oil sands plants. Altogether eliminating the use of caustic soda in gravity induced flotation of bitumen froth currently is not an option since the required residence time in commercial flotation vessels would be prohibitive.
However, imposing a centrifugal force field on the oil sand suspension, instead of a gravity force field, may well increase the rise velocity of bitumen droplets in a major way and may thereby reduce or eliminate the need for caustic soda additions in mined oil sand bitumen extraction.
This becomes particularly important when recycle water is used in the extraction, which recycle water contains enough detergents to disengage bitumen from oil sand solids and may not need further caustic soda additions to disperse the oil sand slurry if a hydrocyclone with helical conduit is used to impose a centrifugal force field on the oil sand suspension for separation by froth flotation.
FIG. 4A illustrates the top view of a hydrocyclone using a helical conduit 404 in the form of a spiral consisting of sections that are joined by flanges 420.
Suspension enters from a supply pipe 401 and flows to the inlet 403 of the conduit 404 where an open vessel 408 where an open vessel splits the suspension into an overflow 407 and an underflow 406.
Fluid enters the suspension through nozzles 405. For the convenience of drawing, these nozzles are shown mounted along the outside lane of the conduit. However, such nozzles Jan Kruyer, Thorsby, Alberta, Canada may be mounted along the conduit in any direction entering the cross section of the conduit 404 in any plane. The flanges 420 serve to connect sections of the spiral conduit 404 but also may be used for the insertion of restrictions in the path of the conduit. Such restrictions are used to mix the suspension within the conduit after the injection of a fluid from one or more nozzles. Various types of restrictions are shown in FIGs 4B, 4C and 4D.
In the case of FIG. 4B the restriction is simply a plate 412 inserted between flanges 411 in which the plate has a hole with a size that is smaller than the internal size of the conduit. The resulting restriction causes turbulence in the suspension and this turbulence causes mixing of the suspension. Flow lines 420 are shown in these Figures to provide some indication of the flow patterns around an obstruction in the conduits. The described hole in the plate may be in the form of a circle or it may be in the form of a half moon. The half moon may have the same diameter as the internal diameter of the conduit, and may be in line with the conduit inside wall along the outside lane, while the straight section of the half moon is close to the centre of the flowing suspension, half way between the outer lane and the inner lane. Such a half moon restriction is illustrated in FIG. 4E and will not restrict the flow of suspension in the outer lane but will cause the suspension of the inner lane to mix with the suspension in the outer lane after having passed the half moon restriction. In the case of FIG. 4C the restriction is a half moon with an attachment that is deformed in the direction of flow of the suspension to provide for mixing of the suspension but with less turbulence as compared with the un-deformed half moon of FIG. 4B. In the case of FIG. 4D
the restriction is contoured in the form of a half ventury. Venturies are often used to locally increase the velocity in a conduit with minimal turbulence. In the case of the half venture of FIG. 4D, the outside lane is not disturbed but the inside lane suspension is accelerated, causing mixing of the inside lane suspension with the outside lane suspension while minimizing undesired turbulence in the conduit, as shown by the flow pattern 420.
Porous sections, each enclosed by a pressure chamber for holding fluid, also may be inserted between the flanges of FIG. 4 to replace the need for some or all of the nozzles.
In FIG. 5 the hydrocyclone with helical conduit is used to clean up bitumen froth with the use of an aperture oleophilic wall. Suspension enters the helical conduit at the inlet Jan Kruyer, Thorsby, Alberta, Canada 501 of the conduit and enters the open vessel 512 after passing nozzles 513 for fluid injection in the suspension. The underflow 503 leaves the hydrocyclone open vessel tangentially at the bottom.
It should be noted here that the bottom of a hydrocyclone of the present invention refers to the opposite end of the open vessel as to where the helical conduit connects to the open vessel. Thus the top of an open vessel of the present invention is that half of the length of the open vessel where the suspension from a helical conduit enters the open vessel, and the bottom of the open vessel is the opposite half of the length of that open vessel. This convention is used for describing the hydrocyclones of the present invention, since these hydrocyclones may be mounted with their open vessel axes vertical, horizontal or at an incline. In cases where the centrifugal force field is very much larger than the force of gravity, the force of gravity has little influence on the operation of hydrocyclones of the present invention. These hydrocyclones may then be mounted with the open vessel axis vertical, horizontal or at an incline, whichever is more suitable for mounting or connecting each hydrocyclone. The orientation of these hydrocyclones is a design consideration that may be based on the size and density of solids in the suspension and the strength of the centrifugal force field in comparison with the strength of the gravitational force field present in the flowing suspension.
In the case of FIG. 5 the hydrocyclone is mounted with the open vessel axis horizontal. The overflow 502 outlet is operatively connected to a vortex finder 504 and the overflow enters a central inlet 532 of an agglomerator 530. Agglomerators of this type are described in detail in Canadian copending patent application No. 2,647,855 filed 15 January 2009 entitled: "Design of Endless Cable Multiple Wrap Bitumen Extractors ".
Such agglomerators often are partly filled with oleophilic balls 533 as shown in the section cut out of the drum 530 wall. A convenient level of balls inside the drum is shown by an immaginary line 534 drawn on the drum end wall. The overflow 502 from the hydrocyclone flows into the agglomerator 530 through a central opening 532 that contains a rotary seal to prevent suspension to spill out of the drum past the central opening. The hydrocyclone overflow 502 contacts the bed of balls 533 and gives up air in the process due to the Jan Kruyer, Thorsby, Alberta, Canada kneading action of the bed of balls and this air escapes through the open apertures 531 of the drum 530 cylindrical wall along the upper half of the drum. Water and some solids also are released from the overflow 502 that has entered the drum 530 due to the kneading action of the bed of oleophilic balls that capture bitumen but allow water and some hydrophilic solids to escape through the bottom apertures 539 of the drum 530 and through the apertures of the oleophilic apertured belt 535 that surrounds the bottom of the drum 530. The kneading action of the balls 533 only temporarily holds the bitumen of the overflow 502 until the amount of bitumen exceeds the holding capacity of the bed of balls, which bed then releases the excess bitumen to the oleophilic apertured belt 535 through the drum apertures 539 along the bottom right quadrant of the drum 530 of FIG. 5. From there the adhering bitumen, which by that time, compared with the hydrocyclone overflow 502, has lost most of its gas or air and a portion of its water and hydrophilic solids, is conveyed upward towards a set of rollers 538. These rollers are squeeze roller 538, which squeeze the adhering bitumen from the apertured oleophilic wall into a receiver 536 for subsequent continuous removal as the bitumen product 537 of separation. This bitumen product 537 normally is a flowing liquid that contains little or no air and contains a lower water and hydrophilic solids content than the overflow 502 from a hydrocyclone. Water and hydrophilic solids removed in this manner from the overflow 502 flow through the apertures 539 of the drum and of the apertured oleophilic belt into a tailings receiver 540 to become the tailings 541 of oleophilic separation, which then is the effluent 542 that is discarded.

FIG. 6 is a flow diagram of an apertured oleophilic wall separator operatively connected with the helical conduit of a hydrocyclone of the present invention to recover bitumen from tailings pond sludge by the separator, followed by a preliminary bitumen product clean up by the hydrocyclone system. The oleophilic wall separator is very similar to the separator of FIG. 5 of copending Canadian Patent Application No.
2,647,855 entitled "Design of Endless Cable Multiple Wrap Bitumen Extractors " and the hydrocyclone is very similar to FIG. 2A of the present invention.
Sludge may have resided in a tailings pond for a long time and during that time the bitumen in that sludge tends to be oxidize, resulting in the formation of acidic components in Jan Kruyer, Thorsby, Alberta, Canada that bitumen. The acidity of bitumen may be measured by titrating bitumen with a strong base, such as potassium hydroxide in a solvent such as alcohol. The measured acidity of the bitumen sample is then reported as TAN, which means "total acid number".
Bitumen with a high TAN represents an upgrading and refining problem because its acidity will corrode process equipment at elevated temperatures unless special and expensive metals are used to prevent such corrosion. Acids or bases may be injected into the suspension in the conduit to react with the organic acids and thereby reduce the TAN of the suspension bitumen. The bitumen product from sludge also contains solids that may be removed in part by injecting one or more depressant reagent fluids through the wall of the helical conduit into the flowing suspension. Fluid reagents injected through the conduit wall may include a strong base, such as calcium hydroxide, sodium hydroxide, or potassium hydroxide and may also include depressants or modifiers. Sodium silicate may be used as an effective depressant for the silica surfaces of some sludge fines. Other depressants may be used as well to remove pyrite particles, as well as particles of zircon, iron bearing ore particles and titanium minerals from the bitumen containing suspension. In some cases the injected fluid may be in the form of a suspension, such as, for example, milk of lime.
With reference to FIG. 6, sludge 601 is fed via a distributor 602 to the top flight 603 of an aperture oleophilic wall separator where aqueous phase passes through the apertures and flows into a drum agglomerator 604 with apertured cylindrical wall 605.
Bitumen captured by the top flight 603 from the sludge 601 is removed by squeeze rollers 606 and becomes the primary bitumen product 607. The aqueous phase entering through the drum apertures 605 contacts a bed of oleophilic balls 608 which capture additional bitumen, and then the bitumen depleted aqueous phase leaves through the drum apertures and through the apertures of the bottom flight 609 to become the final tailings of sludge separation. The kneading action of the balls in the bed 608 transfers bitumen to the bottom flight along the bottom right quadrant 610 of the aperture agglomerator drum 604 and the bottom flight 609 conveys this bitumen to a second set of squeeze rollers 611 to produce a secondary bitumen product 612. The primary bitumen product 607 and the secondary bitumen product 612 are combined as a combined bitumen product 613 which is pumped by means of a pump Jan Kruyer, Thorsby, Alberta, Canada into the entrance of a helical conduit 614 of a hydrocyclone of the present invention. The pump is driven by an electric motor (not shown). The hydrocyclone of FIG. 6 is similar to the hydrocyclones illustrated in FIG. 2 or FIG. 4. Several aqueous reagents fluids 615 may be introduced into the suspension through the conduit wall by means of apertures or by nozzles 616 to achieve the desired surface chemistry modification, the desired neutralizing to reduce TAN and the desired frothing of bitumen before the suspension separates into an underflow and an overflow of the hydrocyclone open vessel. The underflow 617 will contain water and hydrophilic solids and the overflow 618 will contain bitumen froth that with a smaller amount of solids than the amount of solids in the combined bitumen product 613 pumped into the conduit 614 inlet. When inorganic bases are injected through the conduit wall for reacting with organic acids in the combined bitumen product 613 mixture, the reduced TAN of the overflow 618 froth will make the contained bitumen less corrosive.
FIG. 7 is a flow diagram of two hydrocyclones in series. Suspension from a mixing tank enters the suction inlet 701 of a pump 702 driven by an electric motor (not shown) and enters the conduit 703 of the first hydrocylone 704 under pressure. Gas 705 and/or reagent fluid 706 may be injected into the flowing suspension through the conduit 703 wall. In this case the open vessel 707 of the first hydrocyclone is provided with a conical bottom 708 provided with an outlet 709 for underflow 710. In this case the underflow 710 may consist of coarse solids that need to be removed from the suspension before a more effective froth flotation can take place in a second hydrocyclone 714. The overflow from the first hydrocyclone then flows into the inlet of the helical conduit 713 of a second, probably smaller, hydrocyclone. A vortex finder 711 inside the open vessel 707 is connected to an overflow outlet 712 which is connected to the conduit 713 of the second hydrocyclone 714.
Gas and a variety of reagent fluids may be injected through the conduit 713 if the second hydrocyclone into the suspension. Overflow 716 and underflow 717 leaves from the open vessel 715 of the second hydrocyclone. Note that the open vessel of the first, larger hydrocyclone is mounted with the axis vertical to allow convenient and unobstructed removal of coarse and heavy solids through the conical outlet. This is done in cases where the first hydrocyclone is very much larger than the second hydrocyclone and when the Jan Kruyer, Thorsby, Alberta, Canada suspension speed in the swirl path of the large hydrocyclone open vessel is low. In contrast, the second hydrocyclone may be much smaller with a suspension speed in the swirl path of the small hydrocyclone that is much higher. In that case the hydrocyclone open vessel may be mounted with a horizontal axis since the force field of gravity is negligible in comparison with the centrifugal force field. Consequently, selecting and designing the mounting alignment of hydrocyclones of the present invention is influenced by the ratio of centrifugal force field over gravitational force field. The diameter of the open vessel and the sizes and densities of the underflow particles have an impact, as well, on the selection of the most appropriate mounting of hydrocyclones of the present invention.
Thus, as described, hydrocyclones may be used in series with one or more apertured oleophilic walls to efficiently process bitumen containing suspensions; first to concentrate the bitumen and oleophilic solids by froth flotation in a centrifugal force field, using one or more hydrocylcones of the present invention; and then to remove gas or air and water and hydrophilic solids from the final overflow from these hydrocyclones by means of aperture oleophilic walls. Alternately, or in addition the hydrocyclones of the present invention may be used to process bitumen product from conventional froth flotation or from and aperture oleophilic wall. In this manner, oil sand suspensions, and any other suspensions that contain bitumen, may be processed quickly and efficiently while producing a good quality product.
In yet another application of the present invention comminuted minerals may separated by froth flotation in a centrifugal force field, Of course, it is to be understood that the above-described arrangements, and specific examples and uses, are only illustrative of the application of the principles of the present invention. Furthermore, the inventions described in copending patent applications of the present inventor may be combined with the present invention for more effective processing of a range of suspensions of many types. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present invention and the appended claims are intended to cover such modifications and arrangements. Thus, while the present invention has been described above with particularity and detail in connection with what is presently deemed to be the most Jan Kruyer, Thorsby, Alberta, Canada practical and preferred embodiments of the invention, it will be apparent to those of ordinary skill in the art that numerous modifications, including, but not limited to, variations in size, materials, shape, form, function and manner of operation, assembly and use may be made without departing from the principles and concepts set forth herein.

10

Claims (20)

What is claimed is:

1 A method for separating an aqueous bitumen containing suspension by froth flotation in a centrifugal force field using at least one hydrocyclone open vessel each open vessel having an external outlet for underflow an external outlet for overflow and a tangential external inlet for suspension, wherein a) the suspension flows through a helical conduit operatively connected to the open vessel inlet before entering the open vessel, wherein b) the helical conduit of each hydrocyclone has an entrance for accepting suspension under pressure and the helical conduit is either a helical pipe, or a helical rectangular, round or square tube or a helical hose in the helical form of a coil or in the helical form of a spiral, wherein c) the suspension enters the conduit entrance at a pressure that is at least kPa higher than the pressure of suspension leaving the open vessel through an outlet, wherein d) the suspension flowing in the helical conduit is exposed to a centrifugal force field, wherein e) fluid is injected into the suspension through one or more apertures in the wall of the conduit, wherein f) suspension leaves the open vessel through underflow outlet as aqueous hydrocyclone underflow containing suspended hydrophilic solids, wherein g) the open vessel external overflow outlet is operatively connected to a vortex finder inside the open vessel, and wherein h) suspension leaves the open vessel through vortex finder and overflow outlet as hydrocyclone overflow containing bitumen froth aerated with at least 15 volume percent gas.

2 A method as in claim 1 wherein the overflow includes bitumen froth that contains at least 30 volume percent gas.

3 A method as in claim 1 wherein the overflow of at least one hydrocyclone flows into the helical conduit of another hydrocyclone.

4 A method as in claim 1 wherein the underflow of at least one hydrocyclone flows into the helical conduit of another hydrocyclone.

A method as in claim 1 wherein the suspension is a bitumen containing aqueous suspension comprising one of a group comprising oil sand ore digested in water, middlings from a commercial oil sands plant, primary tailings from a commercial oil sands plant, secondary tailings from a commercial oil sands plant, or fluid tailings sludge from a mined oil sands tailings pond which sludge may be fresh fine tailings, fine tailings or mature fine tailings, each of these suspensions containing at least 10 weight percent solids.

6 A method as in claim 1 wherein the suspension is a bitumen froth produced by froth flotation or is a bitumen product produced by an aperture oleophilic wall.

7 A method as in claim 1 wherein the suspension comprises a suspension of tailings pond water that contains between 2 and 10 weight percent suspended fine solids and/or bitumen.

8 A method as in claim 1 wherein the suspension contains bitumen and solids suspended in water said water comprising at least eighty percent recycle water from a mined oil sands tailings pond.

9 A method as in claim 1 wherein the fluid is or contains compressed gas.

52 A method as in claim 1 wherein the fluid is a hydrocarbon or hydrocarbon mixture

11 A method as in claim 1 wherein the fluid is a collector, an activator, a depressant, a frother, a flotation modifier or a reagent dissolved or suspended in water.

12 A method as in claim 1 wherein the overflow flows to an aperture oleophilic wall to remove air, and water.

13 A method as in claim 1 wherein the overflow flows into an agglomerator to remove air and water.

14 A method as in claim 1 wherein a restriction in the conduit serves to mix the suspension with a fluid after the fluid is injected through the conduit wall.

A method for separating an aqueous suspension of mined and comminuted minerals by froth flotation in a centrifugal force field using at least one hydrocyclone open vessel each open vessel having an external outlet for underflow an external outlet for overflow and a tangential external inlet for suspension, wherein a) the suspension flows through a helical conduit operatively connected to the open vessel inlet before entering the open vessel, wherein b) the helical conduit of each hydrocyclone has an entrance for accepting suspension under pressure and the helical conduit is either a helical pipe, or a helical rectangular, round or square tube or a helical hose in the helical form of a coil or in the helical form of a spiral, wherein c) the suspension enters the conduit entrance at a pressure that is at least kPa higher than the pressure of suspension leaving the open vessel through an outlet, wherein d) the suspension flowing in the helical conduit is exposed to a centrifugal force field, wherein e) fluid is injected into the suspension through one or more apertures in the wall of the conduit, wherein f) suspension leaves the open vessel through underflow outlet as aqueous hydrocyclone underflow containing suspended hydrophilic solids, wherein g) the open vessel external overflow outlet is operatively connected to a vortex finder inside the open vessel, and wherein h) suspension leaves the open vessel through vortex finder and overflow outlet as hydrocyclone overflow containing hydrophobic solids froth aerated with at least 30 volume percent gas.

16 A method as in claim 15 wherein the fluid is a collector, an activator, a depressant, a frother, a flotation modifier or a reagent dissolved or suspended in water.

17 A method as in claim 15 wherein the fluid is or contains compressed gas.

18 A method as in claim 15 wherein a restriction in the conduit serves to mix the suspension with a fluid after the fluid is injected through the conduit wall.

19 A method as in claim 15 wherein the overflow of at least one hydrocyclone flows into the helical conduit of another hydrocyclone.

20 A method as in claim 15 wherein the underflow of at least one hydrocyclone flows into the helical conduit of another hydrocyclone.