Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
  • B03D1/00—Flotation
  • B03D1/02—Froth-flotation processes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
  • B03D1/00—Flotation
  • B03D1/08—Subsequent treatment of concentrated product
  • B03D1/082—Subsequent treatment of concentrated product of the froth product, e.g. washing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
  • B03D1/00—Flotation
  • B03D1/14—Flotation machines
  • B03D1/1481—Flotation machines with a plurality of parallel plates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
  • B03D1/00—Flotation
  • B03D1/14—Flotation machines
  • B03D1/24—Pneumatic

Definitions

• This invention relates to froth flotation and more particularly, to column froth flotation for beneficiating mineral ores and the like
• Froth flotation has been used to beneficiate a variety of mineral ores and to effect separation of various other materials for many years.
• Froth flotation involves the separation of particles from each other in a liquid pulp based on differences in hydrophobicity. The pulp is aerated by introducing a plurality of minute air bubbles into it. The air bubbles tend to attach to the floatable (hydrophobic) particles and cause those particles to rise to the surface as a froth product which overflows from the flotation device, leaving behind the non-floatable (hydrophilic) particles.
• a further object of the invention is to provide a froth flotation device and process which requires minimal amounts of water and energy.
• a still further object of the invention is to provide a froth flotation column which does not require an air diffuser having a tendency to become plugged during operation.
• the invention provides a froth flotation device including a tubular flotation column, packing means disposed in the column defining a large number of small flow passages extending in a circuitous pattern between the upper and lower portions of the column, pulp feed means for introducing an aqueous pulp into the column at an intermediate location for flow through the flow passages, means for introducing wash water into the upper portion of the column for downward flow through the flow passages, means for introducing a pressurized inert gas into the lower portion of the column for upward flow through the flow passages, means for discharging a froth fraction containing floated particles of the aqueous pulp from the upper portion of the column, and means for discharging a tailing fraction containing unfloated particles of the aqueous pulp from the lower portion of the column.
• An aqueous pulp containing a mixture of floatable and non-floatable particles is introduced into a column.
• the inert gas preferably air
• the inert gas is broken into fine bubbles as it is forced upwardly through the flow passages in the packing. These bubbles intimately contact the floatable particles and form a froth concentrate or float fraction which contains the floatable particles and overflows from the top portion of the column.
• the wash water, flowing through the flow passages in the packing countercurrently to the float fraction, removes entrained non-floatable particles from the float fraction and a tailing fraction containing the non-floatable particles is withdrawn from the bottom of the column.
• the packing comprises a plurality of vertically spaced plates and spacer means for laterally spacing the plates apart to define a plurality of small flow passages between adjacent plates.
• the spacer means can comprise rows of corrugations on each of the plates, preferably extending diagonally relative to the horizontal.
• separate, vertically adjacent sections of the plates are provided. These sections preferably are oriented so that the vertical planes of the plates in one section are angularly related to the vertical planes of the plates in the adjacent section.
• Fig. 1 is a schematic representation of a froth flotation column embodying the invention.
• Fig. 2 is an exploded, perspective view of a portion of the corrugated plates making up one section of packing for the column illustrated in Fig. 1.
• the column flotation device and process of the invention can be used to separate a wide variety of materials in a broad range of particle sizes. It is particularly adaptable for separation of mineral values from the gangue in fine-grained ores, such as low-grade, oxidized taconite ores from the Lake Superior area.
• the invention will be described in connection with that application.
• the flotation device 10 provided by the invention includes a tubular column 12 having an upper portion 14 and a lower portion 16. a pulp inlet 18 for introducing a conditioned aqueous slurry or pulp of an oxidized taconite ore. into the column at an intermediate location, a water inlet 20 for introducing wash water into the upper portion of the column 12, and a gas inlet 22 for introducing a pressurized gas, such as air, into the lower portion 16 of the column 12.
• the column 12 can be generally upright or vertical as illustrated in Fig. 1 or inclined at angle to the vertical.
• the column 12 is partially filled with a packing 24 which defines a large number of small flow passages extending in a circuitous or tortuous pattern between the upper and lower portions 14 and 16. Wash water introduced into the upper portion 14 of the column 12 through the water inlet 20 flows downwardly through these flow passages. Pressurized air introduced into the lower portion 16 of the column 12 through the gas inlet 22 is forced upwardly through these flow passages, countercurrently to the wash water and the portion of the aqueous pulp descending through these flow passages.
• wash water descending through the flow passages in the packing 24 induces entrained non-floatable particles to separate from the froth concentrate and drop by gravity (i.e., sink) through these flow passages.
• the wash water can be introduced into the column 12 in any convenient manner, it preferably is introduced into the froth chamber 26 and above the top surface of the froth concentrate 26 through a spray nozzle 32 centrally disposed in the top of the column 12.
• the spray nozzle 32 distributes multiple streams of water over the froth in the froth chamber 26, thereby insuring a more uniform contact of the wash water with non-floatable particles in the froth concentrate 25 and also a more uniform distribution of the wash water through the flow passages in the packing 24.
• a tailing fraction 33 containing the non-floatable particles in the aqueous pulp collects in a tailing chamber 32 at the bottom of the column 12 and is discharged therefrom through an outlet 34.
• the tailing chamber 32 preferably is conically shaped as illustrated in Fig. 1 to promote discharge of the tailing fraction.
• the tailing fraction preferably is withdrawn through the outlet 34 by a conventional variable flow pump 36.
• the column 12 can have various cross-sectional configurations, in the specific construction illustrated, it has a square cross section. The cross sectional dimensions and length of the column 12 are governed by the type of aqueous pulp being treated, the particular type of packing used, the desired throughput, and other variables familiar to those skilled in the art.
• the packing 24 can be in a variety of different forms capable of providing a substantially plugged flow condition and defining a large number of flow passages extending in a circuitous or tortuous pattern between the upper and lower portions of the column 12. These flow passages cause the air bubbles to break up and combine into fine bubbles of relatively uniform size, thereby maximizing intimate surface area contact with the floatable particles.
• Suitable packing includes conventional packing materials used in packed tower for vapor-liquid transfer operations, such as Raschig rings. Berl saddles, partition rings, and the like.
• the packing 24 consists of a plurality of sections 38a-38f of vertical extending plates 40.
• Each section includes a plurality of the plates 40 and spacer means for laterally spacing the plates 40 apart to define a plurality of relatively small flow passages between adjacent plates 40.
• spacer means comprises uniformly spaced rows of corrugations 42 on each plate 40.
• the corrugations 42 preferably extend diagonally, e.g., at an angle of approximately 45° to the horizontal, to eliminate vertical flow passages of substantial length.
• the angular orientation of the corrugations can be varied to control flow through the flow passage. For instance, this flow can be increased by increasing the angle of the corrugations 42 to the horizontal.
• the corrugations 42 of alternate plates 40 preferably extend in the opposite direction as illustrated in Fig. 2. That is, the corrugations on one plate extend at an angle to the corrugations on the next plate. Also, alternate sections are positioned so that the vertical planes of the plates in one section are angularly related (e.g., at about 90°) to the vertical planes of the plates in the adjacent section. Referring to Fig. 1, the vertical planes of the plates 40 in sections 38a. 38c, and 38e extend perpendicularly to the plane of the page and the vertical planes of the plates in sections 38b, 38d and 38f extend parallel to the plane of the page.
• the packing sections 38c and 38d in the vicinity of the pulp inlet 38 preferably are spaced apart to provide a substantially unobstructed feed compartment or chamber 44.
• the packing sections 38a, 38b, and 38c above the feed chamber 44 make up the primary cleaning section of the column 12 and the packing sections 38d, 38e and 38f below the feed chamber 44 make up a scavenging section wherein the floatable particles are separated from the descending tailings.
• an iron ore such as oxidized taconite
• An aqueous slurry or pulp of the particles is introduced into a stirred conditioning vessel 46 for the addition and admixing of suitable flotation reagents.
• a cationic collector or an anionic collector for calcium activated s ilica
• a suitable anionic collector such as a fatty acid type collector, is added to and thoroughly mixed with the aqueous pulp in the conditioning vessel 46.
• conditioning reagents can be used depending primarily on the material being treated and the type of flotation.
• the frothing agent can be incorporated into the pulp before, after, or together with the collector. If the frothing agent is added separately, the pulp is mixed for a sufficient time to insure uniform dispersion of the frothing agent throughout the pulp.
• the pulp is withdrawn from the conditioning vessel 46 by a pump 48 and introduced into the column through the pulp inlet 18.
• the flow rates of the ore pulp, the air and the wash water can be adjusted to obtain a material balance which provides the most effective separation of the floatable particles (e.g., iron oxide) from the non-floatable particles (e.g., gangue).
• the device and process of the invention have several advantages over conventional flotation devices and processes. They provide all the advantages of conventional flotation columns and further provide increased air-to-particle contact, eliminate the need for a special device in the bottom of the column for generating fine air bubbles, and require less water and energy. More importantly, floatable particles, such as iron oxide, can be more effectively separated from non-floatable particles, such as gangue, with single stage flotation. That is, a conventional flotation column usually requires at least two flotation stages to recover the same amount of iron oxide from a low grade iron ore. In addition to being used for single stage flotation, the device of the invention can be used in combination with conventional flotation machines and two or more can be used in series.
• EXAMPLE 1 A series of laboratory tests were run on an experimental column consisting of a 2-inch I.D. tube, 8 feet long and almost entirely packed with 2-inch long conventional brass tower packing cylinders.
• Samples of -10 mesh oxidized taconite ore obtained from the Cascade deposit owned by Cleveland-Cliffs Iron Company
• Samples of -10 mesh oxidized taconite ore were ground batchwise at 60 weight % solids in a rod mill in the presence of water for about 20 minutes to produce a slurry or pulp of about 80 weight % passing 500 mesh.
• the pulp was conditioned with a conditioning reagent prepared in accordance with U.S. Patent 4,132,635 and the pH was adjusted to 8.8 by adding soda or sulfuric acid.
• the resulting pulp samples were separately introduced into a stirred container where a fatty acid collector (PAMAK-4), No. 2 fuel oil. and a frothing agent were added and mixed into the pulp.
• PAMAK-4 fatty acid collector
• No. 2 fuel oil No
• the conditioned pulp samples containing 20% solids were continuously pumped from the stirred container into the mid-section of the column at a rate of about 130 cc/min. Water was introduced near the top of the column at a flow rate of about 50 cc/min. and air was introduced near the bottom of the column at a flow rate of about 8 1/min.
• FIG. 1 A series of pilot plant tests were run on a column arranged generally in the manner illustrated in Fig. 1 and a conventional 8-stage WEMCO Fagergren flotation machine.
• the column was 20 feet tall, had a 7 1/4 in. X 7 1/4 in. square cross section, and included six 3-foot sections of packing plates.
• Each packing section was packed with 5 layers of corrugated plates.
• the plate corrugations were 1/8 inch high and extended at about 45° to the horizontal, and alternate layers or sections were oriented at 90° to each other.
• An oxidized taconite ore was ground to about 75% -500 mesh and formed into a pulp.
• a conditioning reagent prepared in accordance with U.S. Patent 4,132,635, an anionic collector (PAMAK-4), and No. 2 fuel oil were mixed into the pulp.
• One stream of the conditioned pulp containing about 20 weight % solids was pumped into the feed compartment of the column at a feed rate of about 150 lbs/hr and another stream of the same pulp was processed in the conventional flotation machine.
• Air at a pressure of about 10-12 psig was introduced into a column through the gas inlet at a rate of about 300-500 ft 3 /hr and wash water was sprayed into the froth chamber at a rate of about 30-50 gal/hr.

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• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Biotechnology (AREA)
• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• Paper (AREA)
• Manufacture And Refinement Of Metals (AREA)

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• 1984
  • 1984-05-17 AU AU28329/84A patent/AU561931B2/en not_active Ceased
  • 1984-06-04 CA CA000455766A patent/CA1210167A/en not_active Expired
  • 1984-06-08 FI FI842340A patent/FI75280C/fi not_active IP Right Cessation
  • 1984-06-13 DE DE8484902567T patent/DE3485641D1/de not_active Expired - Lifetime
  • 1984-06-13 WO PCT/US1984/000926 patent/WO1985000021A1/en active IP Right Grant
  • 1984-06-13 EP EP84902567A patent/EP0144421B1/de not_active Expired - Lifetime
  • 1984-06-13 AU AU31004/84A patent/AU3100484A/en not_active Abandoned

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