NZ761110B2 - Liquid aeration - Google Patents

Abstract

spike resistant package (10) comprising a pouch (100) having an inner surface and an outer surface, and a first grouping (200) of spike resistant textile layer. The grouping has a first side (200a), a second side (200b), and comprises plurality of spike resistant textile layers (210). Each spike resistant textile layer comprises a plurality of interwoven yarns or fibers having a tenacity of about 14 or more grams per denier. The package further comprises a slip layer (300) having a thickness of less than about 0.1 mm, a stiffness of less than about 0.01 N-m, and a static coefficient of friction (COF) between the slip layer and the second side of the first grouping of less than about 0.40. The slip layer is located on the second side of the grouping of spike resistant textile layers. The pouch fully encapsulates the grouping of spike resistant textile layers and the slip layer, and the slip layer and the inner surface of the pouch are in direct and intimate contact. The invention provides a flexible light weight structure that resists penetration by spike-like threats, wherein the slip layer provides improved spike resistance compared with prior art multi layer fabric devices. esistant textile layer comprises a plurality of interwoven yarns or fibers having a tenacity of about 14 or more grams per denier. The package further comprises a slip layer (300) having a thickness of less than about 0.1 mm, a stiffness of less than about 0.01 N-m, and a static coefficient of friction (COF) between the slip layer and the second side of the first grouping of less than about 0.40. The slip layer is located on the second side of the grouping of spike resistant textile layers. The pouch fully encapsulates the grouping of spike resistant textile layers and the slip layer, and the slip layer and the inner surface of the pouch are in direct and intimate contact. The invention provides a flexible light weight structure that resists penetration by spike-like threats, wherein the slip layer provides improved spike resistance compared with prior art multi layer fabric devices.

Description

se the Vaiue of a Sulphide Ore Resource h Sequential Waste Rejection OUND TO THE INVENTION de ores containing metais such as copper, gold, platinum group metais, nickel, lead and zinc are recovered commerciaiiy by fine grinding and flotation to concentrate the valuable component and discard the The conventional process invoives grade control drilling to delineate the ore, blasting the necessary waste (below economic cutoff-grade (00(3)) and ore, ioading trucks to haui the ore for primary crushing and the waste to a. disposal area. The crushed ore is conveyed to a miiling process, typicaliy using semi-autogenous grinding (SAG) or high pressure grinding rolls (HPGR); foilowed by bali miiiing to fuily te the valuable particles at a p80 of around 75—200 micron. Then the ore is separated using a flotation process to produce a saleabie concentrate and taiiings. The tailings from flotation are pumped to a taiiings storage facility (TSF) and stored in perpetuity.

As the conventional process chain requires ali of the ore to be ground finely, it consumes large quantities of energy (typicaliy ZOkwhl’t ore) and water .0 tonne water per tonne of ore). The majority of this water is lost in the fine tailings, where it is intimately mixed and retained with the very fine residue produced from the conventional flotation process.

The shortage of available water in some ons has generated different approaches to water . Some mines have instailed desalination piants on the adjacent coast, and pumped the desaiinated water to the processing faciiity. Others have led large filter presses to squeeze as much water from taiiings as possible. However these solutions both suffer very high capitai and operating costs. The high cost of fine grinding and high water consumption aiso means the recovery efficiency of the in~ground resource is limited to that which is economic to process.

At any particular time in the mine iife, the (DOS for ore is set to maximise the feed grade and hence production from the avaiiabie processing capacity.

This CoG may be variously ained by available water, or tailings capacity, or the ied processing capacity. Whichever constraint s, economically attractive ore is often being rejected to a waste pile, simply because higher grade materials are available at the time. Even if a low grade stockpile is introduced to manage the material which is above economic processing grade but beiow the 008 of the day, the materials handling cost of stockpiling and reclaiming this marginally attractive material iater in the mine life, impiies a fraction of the economic resource wiil be lost to the waste rock piie.

If the run—ofnmine ore couid be ciated prior to fine ng, to reject as waste material which is below economic -grade, with a high recovery of the values and a reasonabiy high upgrade ratio, and in a relatively low cost operation, the unit costs and consumption of water would be reduced. The consequential grade of feed to processing wouid be increased. And the grade of any stockpile required by a constraint to avaiiable processing capacity would be higher, resuiting in improved margins when eventuaily recovered.

Recognising the value associated with removing a fraction of the ore that is below 606, and preferably beiow economic treatment grade, various beneficiation techniques have been proposed. For sulphides, these are y based around gravity techniques such as dense media separation, spirais, etc, and rock sorting methods. But for most suiphide ores, these ciation techniques iaii either the upgrade ratio/recovery or cost hurdles for implementation. if the beneficiation parameters are set to reject sufficient ore (i.e. achieve a high upgrade ratio) to economically warrant the cost of the beneficiation process, the loss of values is excessive. This means an increase in mining cost per tonne of t, and a decrease in the ive utilisation of the overall resource.

Hence run of mine (ROM) ores are conventionally ground to very fine sizes to achieve te liberation of the valuabie components then d, despite the obviously high cost of comminution and water consumption.

Recently, the ability to use a chemically based coarse flotation process for beneficiating des, using a fit for purpose ion cell has been ed by Eriez Flotation Division (EFD), a wholly owned subsidiary of Eriez Manufacturing Co. Using this coarse flotation technology, the ability to dry stack sand residue was recognised, thus opening up another potential beneficiation technique to reduce water and energy (W02016l170437). As a one off process for water recovery, it is very useful, but due to particle size vs. ry constraints on coarse flotation, and the size separation precision of hydrocyciones, only 30—50% of the ore ends up as sand. Hence water consumptions and tailings volumes are typically only reduced by some 25-40%. in a second beneficiation technique for sulphidic ores, the differential fracture along the mineraiised grain boundaries, causing most of the sulphides to concentrate in'the finer size ranges, has been recognised.

The differential fracture s ing to reject the coarsest rocks, which usually contain the lowest grade. This technique was first uced in Bougainville in the late 19808 (Australasian institute of Mining and Metallurgy, Papua New Guinea Minerai Development Symposium, 27-28 June 1986, Madang, The Application or Preconcentration by Screening at Bougainville Copper Limited, Bums RS and Grimes AW, the content of which is incorporated herein by reference). The beneficiation technique is being actively reexamined by a number of operations under the CRC Ore trademark of ‘Grade Engineering'. CRC ORE is a not for profit organisation funded by the Australian Federal ment and the giobal ls industry httg:!lwww.crcore.orgau/mainlindex. phpleatutions/grade engineering.

And finally, beneficiating using bulk sorting has aiso been proposed. The development of sensors that can adequately ine average grades on a conveyor belt or shovel at a high rate, allows for the stream of broken rock to be identified and diverted to either ore or waste. Reference: Valery etai. World Mining Congress 2016; nse http:/Iwww.minesensesomlgroducts : The ShovelSenseTM shovel t is a real-time mineral telemetry and decision support system for surface or underground ations. it is a retrofit package installed in the dipper of surface shovels or into the scoop of underground machines such as scooptrams or LHD’s. The ShovelSense"M rm is used for: Measurement of ore quality while material is being scooped into the dipper; Reporting of ore quality and type to the grade controi/ore routing system Realutime, oniine decision support for orelwaste dispatch decisions.

Buik sorting takes advantage of the natural heterogeneity of orebodies, with the separation of zones of high and low grade material that would conventionaliy be mixed into homogenised run~ot~mine ore. The weakness of bulk sorting is it can only reject those zones that are low grade at the time of sensing, and hence to retain an acceptabie upgrade ratio it must be installed prior to significant homogenisation of the ore.

Despite these three recent and quite ct beneficiation techniques being veiy well known, none has yet found widespread use in the mining industry. This may be at least partialiy attributed to the same upgrade ratio, recovery, and cost reasons that have hampered the implementation of traditionai gravity based beneficiation. in y, the mining industry is very l intensive, a iarge consumer of water and energy, and oniy partialiy recovers the values contained in the earth that is mined. Whilst beneficiation techniques are known which can potentially address these , they have been considered in isolation to resolve each constraint individually, and mostly found to be uneconomic.

SUMMARY OF THE lNVENTlON According to the present invention there is provided an integrated process for recovering vaiue metals from sulphide ore, including the steps of: a) obtaining a crushed ore; b) bulk sorting and screening the crushed ore to provide a sortedlscreened coarse ore stream and a waste ore stream; c) subjecting the sorted/screened coarse ore stream to ng in a mill foliowed by classification to provide a coarse fraction suitabie for coarse flotation and a first tine fraction le for conventional flotation; d) subjecting the coarse fraction suitable for coarse flotation to coarse ion thereby to obtain a gangue and an intermediate concentrate; e) ting the intermediate concentrate to grinding to provide a second fine traction suitable for conventions! flotation; and f) subjecting the first fine fraction and the second tine fraction to conventional flotation to provide a concentrate and tailings.

Preferably, blending of the crushed ore is limited, for example to a truck load or shovel load, in order to limit homogenisation of the ore prior to step At step a), the ore is preferably crushed to a size suitable for tation on a or, as a feed to a subsequent grinding stage, and is typically in the range of 5 to 40 cm.

The bulk sorting in step b) may be on a buik sorter comprising a conveyor beit with a diverter mechanism controlled by a continuous analysis sensor, wherein the diverter mechanism diverts low grade zones of rock which do not meet a selected cut off grade (COG) to the waste stream. The continuous analysis sensor preferabiy comprises a rapid scanning sensor, preferably a ic resonance or neutron activation or X-ray sensor. in step b), the crushed ore may be subjected to buik sorting followed by screening or screening foliowed by bulk sorting.

Preferably, at step b), the d ore is subjected to bulk sorting to provide a sorted coarse ore stream which is subjected in to grinding in step c), and a first waste ore stream.

Advantageousiy. the sorted coarse ore stream is screened to provide a ed coarse ore stream which is subjected to grinding in step c), and a second waste ore stream.

Typicaiiy, the size of screen apertures of a screen used to screen the coarse ore stream are selected to provide a ed coarse ore stream that is about 80-90% by weight of the coarse ore stream from bulk sorting.

Preferably, at step b), the first waste stream is screened to provide a third waste ore stream and a higher grade fraction that is sent for ng in the grinder at step c) together with the sortedlscreened ore stream.

Typically, the size of screen apertures of a screen used to screen the first waste ore stream are ed to recover from 15—25% by weight of the stream.

At step c), the ore is ably ground in ciosed loop with a ciassification circuit, to aliow scatping of material that is already reduced to the appropriate size ranges for coarse and tional flotation. 2017/053963 At step c), the ore is preferably subjected to fication to e a coarse fraction suitable for coarse flotation with a size of 100 pm up to 1000 pm, preferably 150 pm up to 800 pm, most preferably from 200 pm up to 600 pm, and a first fine traction suitable for conventional flotation with a size of less than 100 pm, typicalty less than 150 pm, preferably less than 200 pm.

At step e), the intermediate concentrate is preferabty ground to a size of less than 150 pm to provide a second tine fraction suitabie for tional flotation.

Preferably, a natural grade recovery curves is determined for the ore, and each of the following beneficiation steps: i) buik sorting; ii) ing; iii) coarse flotation; is arranged and controlled to permanently reject the maximum quantity of waste at a grade fess than an economic cut-off—grade.

The beneficiation steps: i) buik sorting; ii) screening; iii) coarse flotation; may be further arranged and controlled to also separate a low grade ore suitabte for stockpiiing or heap ng, and hence produce a high grade feed to fitl the availabte comminution and conventional flotation ty.

For the constraints of a particular mining asset, the design and set points are further selected for each beneficiation step, to: . optimise the production of the whoie mining and processing asset system, within the constraints of water or taiiings storage capacity; and l or WO 34855 . optimise the capital costs of productive assets and infrastructure in a new or expanded mine; and I or . optimise the recovery of mineral vaiues from an orebody; and I or . optimise the overall operating costs per tonne of product by ultimateiy rejecting the maximum waste, at less than the economic cut off grade (CoG) for retreatment.

Preferabiy, homogenisation is minimised prior to bulk sorting to maximise the removal of gangue.

Screening may be used specificaily to scavenge the higher grade fines from the reject stream of bulk g Screening may aiso be used specificaiiy to scavenge the lower grade coarse ai from the ore product stream of bulk sorting.

BRiEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow diagram of a beneficiation process according to an embodiment of the invention; Figure 2 is a graph showing a grade tonnage curve for buik sorting of a typical copper porphyry ore; 3 is a graph of the ing achievable by screening at s proportions of a typicai copper porphyry ore Figure4 is a decision tree for a typical process design for an embodiment of the invention; and Figure 5 is a graph iilustrating the ial impact of the process of the present invention on power consumption, water consumption, and tailings generation in comparison with a conventional crushing, grinding and flotation process.

DESCRIPTiON OF PREFERRED EMBODIMENTS The t invention relates to a process that capitaiises on the natural heterogeneity of sulphide orebodies, and utilises beneficiation technologies in a novel muttistage configuration to reject the maximum ty of waste gangue prior to fine comminution. This rejected gangue is normally below economic reprocessing grade (ie. waste) but might also be in the form of a feed to heap leach; or in the form of a low grade stockpile for treatment later in the mine life (grade profiling).

The exact quantum of benefits will be dependent on the grade recovery characteristics of a particular orebody. However, using combination of the techniques, the water and ution energy consumption are typically reduced by 50-80% at the same mining cut—off—grade (CoG). Alternatively, the mining cut«off—grade can be reduced. extending the life of mine, and e only siightly lower reductions in overall water and energy consumption. The invention also enables unit costs of production, capital and operating, to be icantly reduced, and where appropriate the profile of production to be brought forward to enhance the return on invested A simplified block flowsheet of one embodiment of the invention is shown in Figure 1. An orebody is mined 12 and fed to a primary crusher 14, from where it is bulk sorted to to provide a sorted coarse ore stream 18 for grinding and classifying 20 and a sorted waste stream 22. A screen 24 recovers a high grade finer fraction 26 from the sorted waste stream 22, and this rejoins the high grade stream for grinding and classifying 20. If the sorted coarse ore stream 18 from buik sorting 16 is sufficiently low grade, it can be similarly ed 28 to reject the coarsest material 30 to the waste or low grade stockpile 32. Classification splits the ore after partial grinding into a coarse product stream 34 suitable for coarse flotation 36 and a fine product stream 38 suited to proceed direct to flotation 40. The coarse WO 34855 fiotation process 36 then rejects further gangue 42 to a sand iie 44, with an intermediate concentrate 46 being reground 48 to proceed to conventional ion 40. A concentrate 50 and tailings 52 are obtained from the conventional flotation 40.

Thus, low grade materiai 32 and 44 is rejected from the sorter/screen combination 16/24128, and from the coarse flotation 36, thus requiring only a proportion of the original ore to be finely ground to achieve the full liberation required to produce a saieable concentrate.

The variable nature of ore mineralogy and/or mine designs, means that deportment of the values will be different at each mine. For e at onal mines, it may be le to e the screening and bulk sorting, whilst stili retaining the naturai ore heterogeneity. In this variant, the fine al from screening would proceed to grinding, and the coarse fraction would be bulk sorted to reject waste. The system design would be such as to minimise homogenisation during sorting.

And for some mines with particularly attractive grade recovery curves for one or two of the beneficiation techniques, it may be economicaily more appropriate to utiiise only some of the components of the muiti-stage novel processing chain that is the subject of this invention.

The grade recovery curve for bulk sorting is weii suited to waste removai, providing the nature! spatial heterogeneity of the orebody is retained.

Screening is well suited to scavenging vaiues (the tines) from low grade streams, but only for occasionai orebodies does the selective fracture enable high recoveries and immediate rejection of waste. Coarse ion is well suited to rejection of waste with a high recovery, albeit after partial comminution.

First Comgonent —~ Bulk Sorting The first component beneficiation step in the most common configuration of this invention. is bulk sorting. Ore that has been fragmented by ng, is transported by truck or conveyor to a primary crusher, and by conveyor to grinding. On the conveyor either before or after the primary crusher, the grade of the ore (or deieterious contaminants) can be anaiysed, using techniques such as magnetic resonance, for example an cit—conveyor MR Analyser for a species other than chaicopyrite being devetoped by CSERO in collaboration with CRCOre, which will resuit in the veyor MR technology attaining a TRL 4 for detection of setected non-chalcopyrite mineral targets httgzllwww.crcore.org.au/mainlimages/snagshotlgroiects/CRC-ORE~ Sna shot---Research~i.003-«Buik-sensin with-ma netic-resonance. cit- or neutron activation, for example a cross belt analyser avaiiabie from SODERN which makes use of a CNA (Controiled n er) using an ical neutron source with stabilised emission httg:liwww.sodern.comlsiteslenlret/Cross-belt—Anatyser 7t.htmi, aliowing a decision to divert the stream of rock to ore or to waste. NA is a nuclear process used for determining the concentrations of elements in a vast amount of materials. CNA aliows discrete sampling of elements as it disregards the chemical form of a sample, and focuses solely on its nucleus.

By minimising homogenisation wherever possible in the materiais ng, the high and tow grade zones of ore are retained almost . This point of analysis for bulk sorting may be before or after the primary crushing depending on the nature of fragmentation in blasting. But the bulk sorting must be located prior to a SAG or bait mitt where biending and recirculating loads ate the heterogeneity. Any ediate stockpiles between the mine and the bulk sorter shouid aiso be avoided.

These zones of high and low grade rock, when loaded on the conveyor belt, translate into corresponding iengths. Some sections along the iength of the loaded conveyor belt are below the economic processing cut-oft: grade, while others are made up from the high grade zones. Based on the continuous sensor is, a diverter mechanism is used to divert those iow grade lengths of rock, which do not meet the desired COG, to a separate waste stream.

The typical grade tonnage curve for bulk sorting will be very dependent on the orebody heterogeneity, Through retaining this natural zonai heterogeneity and using a rapid scanning sensor, the effective sorting lot size is considerably smalier than the typical 20~25rn grid used for conventional in—pit grade control. (in conventions? grade l, everything in this grid being averaged and deciared as either ore or waste). Thus, the buik sorting process discriminates more accurately between waste and ore than conventional grade l.

The quantity of rock that is below cut~off~grade, and hence can be d from conventional ore can be estimated from gee-statistical analysis of drill core. Assuming the rock is homogenised at the granularity of a 300i truck delivered to the conveyor, a grade tonnage curve is iilustrated in Figure 2, for a typical copper orebody in Chile, illustrates that up to 25% of the run- of—rnine ore can be rejected as waste.

An even more amenable Piatreef pgm ore from South Africa can yield up to 40% waste rejection at below the processing COG. Similarly, a reasonably homogeneous porphyry copper RoM from Peru, can yield up to 20% waste at beiow the 0.25% COG.

Optionally, the process can be configured such that one stream from the first diverter can be further , using a second diverter system. This technique can be used to create three fractions (high grade stream for immediate processing: and lower grade stream of ore to be iled, or heap d: and a waste stream). This grade ing technique is idealiy suited where mining costs are modest relative to processing, and the orebody is iarge enough to warrant ting of the lower grade on at some later date. if water is highiy constrained, this enabies high production in early years (grade profiling) within an available water constraint. sing the ievei of ng that occurs prior to this bulk sorting sensor and diverter is important to maximise the rejection of low grade ore. The partially blended lot size (eg. a truckload) that can be analysed and diverted is r than that achievable with the spacing of normal grade control drilling. Due to natural orebody heterogeneity, a significant proportion of the conventional RoM feed is below the mine COG, and can be diverted to waste or assigned to a tow grade stockpile.

This eariy rejection of a waste stream that would otherwise be processed as ore, has implications for both resource utilisation and costs. The waste is no longer ground (energy savings) and is stored dry (water savings). The separation efficiency of bulk g is better than grade controi driiling and seiective loading, so that this grade control activity can be limited to delineating the ultimate pit shell, saving r costs and simplifying mining activities. The removal of waste means that unit costs of processing are reduced. and hence a lower COG can be used for this ultimate pit shell.

Thus the l utiiisation of the resource ent can be ed.

Second Component - Screening in the second component of the muitiple beneficiation steps that make up this invention, one or both of the waste and ore streams from butk sorting are screened. Sulphide ores selectively re along the mineralised grain boundaries during biasting and crushing. As such the finest fraction of the rocks in any ore zone will be of a higher grade.

If an ore exhibits a significant selectivity, the waste stream from the bulk sorting is screened to further separate the higher grade, finer fraction.

These smaller rocks, are inciuded in the ore stream. An example of this is shown in Figure 3 for a reasonably selective Chilean copper ore, where the finest 10—20% of the ore. typically exhibits around twice the grade of the remaining 8043096 of the ore. Thus a screening process is used to scavenge those fines, which are higher than the processing cut~off-grade., from the reject stream from bulk sorting. As such, the grade of the waste discard stream is further reduced, thus improving overall resource recovery.

Depending on the particular grade recovery curves for any ore, the set points for each beneficiation process can be selected to optimise the waste rejection by the overall butk sorting/screening system.

Depending on the selectivity of fracture of the particutar ore, this ing will lly require a screen re to recover around 15-25% by weight of the low grade stream. The coarse fraction proceeds to waste.

The high grade ore stream from primary crushing also contains a mix of rock sizes. Due to selective fracture that occurs in blasting, and any crushing undertaken prior to the bulk sorting, the highest grade is concentrated in the finer fraction of rock. Removal of the lower grade coarsest rocks by screening can result in further upgrading of the feed to comminution. Whilst it may be unusual for such coarse material in the reject stream to be below economic processing grade, this fraction may be well suited to heap leach or low grade stockpile. lf screening of the coarsest rocks is applicable, the high grade fines stream will typically be around 80-90% of the total feed from bulk g. However for those ores where selective fracture is not nced, this high grade ing will not produce a sufficient grade differential to warrant the lower grade coarse al being rejected, and hence the screening of the bulk sorted ore will simply not be implemented.

The combined system of bulk sorting and screening of the high and low grade streams will have different optimum set-points for each ore to be d, and for the economic drivers of each mine. lt is apparent to those skilled in the art, that the set-points of the system can readily be optimised to produce the maximum grade for comminution, while rejecting the maximum rock that is at or below the ic cut-off~grade for processing.

Third Component — Coarse Flotation The third stage of the multistage beneficiation is coarse particle flotation.

This process utiiises the heterogeneity at the sand (sub 1mm) size level, for a chemically assisted gravity separation. The partially ground ore is classified to produce a sand fraction, which is beneficiated using a fit for purpose flotation machine such as the Erie}:TM Hydrofioat. The Eriez Hydrofioatm, s out the concentration process based on a combination of fluidization and flotation using fiuidization water which has been aerated with micro—bubbles of air. The flotation is carried out using a suitable tor and collector concentrations and residence time, for the particuiar mineral to be floated. At this size, the ore is sufficientiy ground to liberate most of the gangue and expose but not necessarily fully liberate the valuable l grains. The coarse ion recoveries of ily exposed mineralisation is high, and the residual gangue forms a sand which does not warrant further comminution and conventional flotation. The reject sand from coarse flotation can be stacked and d to recover water.

The system used to select a suitabiy sized feed for coarse flotation utilises ciassitication devices such as cyciones or hydraulic classifiers to scalp that fraction of the stream that is suited to tional flotation. in a typical configuration for this third beneficiation ent, the material at a size less than the upper size iirnit for coarse flotation is separated from the bait miil circulating toad. This stream can then be further fied to separate the materiai that is y ground to below the lower bound for coarse flotation, and this finer fraction is sent directly to conventionai flotation. This creates the feed to coarse flotation at a size in which the residue which is ‘free draining’. in the normai configuration, the coarse flotation size range wiil be bounded by the maximum size where the vaiuabie minerals are sufficiently exposed to be floated, with ient recoveries such as to produce a sand residue suitable to discard. The minimum size is set by the particle size at which the coarse fiotation machine can operate efficiently to e a free draining sand for disposal. Depending on the mineralogy, the fracture characteristics of the ore, and the design of the classification circuit; this lower size range is typically around 0 microns, and the upper size is typically between 350 and 600 micron. ing on the size range for coarse flotation, and the classification efficiency. this scalping captures for coarse flotation between 40—60% of the total feed to comminuticn, with the remainder reporting to conventional flotation. in a conventional froth fiotation process, particle sizes are typicaily fess than 0.1 mm (100 pm). The ore les is mixed with water to form a slurry and the d mineral is rendered hydrophobic by the addition of a surfactant or coilector chemicai. The particular chemical depends on the nature of the mineral to be recovered. This slurry of hydrophobic particles and hydrophilic particles is then introduced to tanks known as flotation cells that are aerated to produce bubbles. The hydrophobic particles attach to the air bubbles, which rise to the e, forming a froth. The froth is removed from the calf, producing a concentrate of the target mineral.

Frothing agents, known as frothers, may be uced to the slurry to promote the formation of a stable froth on top of the flotation cell. The minerals that do not float into the froth are ed to as the flotation tailings orflotation tails. These tailings may also be subjected to further stages of flotation to recover the le particles that did not float the first time. This is known as scavenging.

The undersize from the classification is ideally sized for conventional flotation, as it does not suffer significantly from the poor recoveries that most conventional flotation exhibits with particles above around 200 micron.

The oversize from the initiai classification of the bail mill recirculating load (above the upper bound ed for coarse flotation) is recycled for further comminution. Due to the extended size range that is scalped, the comminution energy is significantly reduced.

The sand residue from coarse flotation has a tow exposed sulphide content. it represents 7043096 of the scalped coarse flotation feed. It has a sufficiently high lic conductivity and can be hydrautically stacked and drained to recover the water.

The intermediate concentrate produced by coarse flotation is the remaining -30% of the coarse flotation feed. This requires regrinding to fully te the minerals, prior to conventional flotation in either the rougher n of conventional flotation along with the fines fraction from the ball mill classification, or direct to the conventional cteaner cells. in a variant to coarse flotation, the size fraction of the feed to coarse flotation can be widened at the upper end to say 0.84.5mm. This variant of the invention is typically utilised when the throughput of the overall mine is constrained by the fine grinding, conventional flotation, or taiiings storage process, including total ble water to the mine. in this t, a greater proportion of the ball mili ulating load is scalped and ciated, aibeit that the coarse fraction of the coarse flotation residue will not be of a grade that can be discarded directly. Some but not most of the coarsest feed material has d sulphide surfaces that will float. Thus the coarse fraction is liy denuded of its values, albeit not sufficiently to justify immediate assignment as waste." 80 the overall residue from coarse flotation, is further classified to separate the partiatly denuded coarse sand that is above the normally selected upper bound for optimum recovery in coarse flotation. This partially denuded coarse material can then be dry stacked for processing tater in the mine life. In this t the throughput capacity of the ball mills is further increased, and the consequential grade profiling enables higher production from conventional flotation early in the mine tife.

Integration of the Beneticiation System WO 34855 By configuring bulk sorting and screening and coarse flotation, the benefits of zones of high and low grade ores, and the differential deportment of mineral values during fragmentation, and the selective liberation and separation of gangue, are synergistic. Bulk sorting utilises the naturai heterogeneity at the ore zone level. Screening captures the natural heterogeneity at the individual rock level. And coarse fiotation captures the heterogeneity at the sand level. The sequential steps are also compensatory, in that there can be a second, modest cost, backstop to avoid ent al of values that may have found their way into the wrong stream in a prior beneficiation step, and reject gangue which has been misplaced into the values .

Whilst the stage beneficiation process may be configured in s ways, the most economic decision for a long life mine is usually to maximise production from existing assets. The decision tree illustrated for this case in Figure 4, is an example of the design ples that can be applied, and the associated rational for selection of set-points.

In Figure 4, the reference numerals indicate: 80 mine, 82 is the Ore above Processing 008?, 64 No, 66 Yes, 68 Waste, i’O Bulk Sort to reject waste, 72 Screen to scavenge vaiues, 74 Set points are seiected (bulk sensor setting and screen size) to maximize the waste rejection at a grade below ic 008, 78 is the available tonnage > processing capacity?, 78 Yes, 80 No, 82 Second stage bulk sort r screen), 84 Classification and CPF, 86 Conventionai flotation, 88 Low grade stockpiie, 90 is throughput further constrained eg. water/tailing?, 92 Yes, 94 No, 98 Classification to recover oversize, 98 Set points are selected for classification sizes to maximise grade and tonnage to conventional flotation whilst maintaining high i processing recovery.

The exact distribution of beneficiation steps and their set~points for every orebody and every optimised business case will be different. As an example, Figure 5 iliustrates the potential impact on power consumption, water consumption, and tailings generation in an atternative configuration of the invention which is directed to increasing mine life, whiist continuing to save water and energy and increase production. Through the ion, a proportion of what would be ently discarded in—pit and expanded pit mineraiised waste in a conventionai mine, is now converted to ore (i_e. above the economic CoG). The expanded source of ore is sorted and screened to reject a substantive fraction of the ore as a waste (‘in pit waste rock' which is below the economic processing CoG). CPF rejects further waste as dry stacked sand, thus the quantity of ore progressing to fine comminution for conventional flotation is considerably d. Since most of the energy and water consumption is attributable to the requisite amount of fine grinding required for conventionai flotation (illustrated by the height of the tailings bar), the water and energy consumption per unit of product is more than halved, and the tits of the resource is extended. in summary, by combining the three ciation processes, each of which relies on a different form of ore geneity; the invention achieves a greater recovery of the vaiues in an orebody through reducing the processing cut-off-grade, and enables more of the gangue to be discarded in dry form, and the potentiai for a low grade ore to be stockpiied prior to fine grinding later in the mine life. This in turn reduces the water consumption and comminution energy, and reduces the amount of taiiings generation to a modest proportion of the originai ore. The resultant operating costs are reduced, and capital productivity of the processing facilities is much enhanced. ages of the process of the present ion are: . Requirements for grade control activities in pit are minimised, enabling simpier .

- The grade of ore to grinding may be sed by more than 10%, and more preferably by 20% and most preferably by more than %.

. The te economic cutoff-grade for mining of an orebody may be reduced by more than 10% and preferably by more than 20%, and more preferably by more than 30%.

. The total amount of fine tailings ed from the conventionai run-of—mine ore may be reduced to tess than 50% of those resutting from conventionat processing technology, and preferably less than 40%, and even more preferably iess than 30%.

. The totat amount of energy used in ution may be reduced to less than 50% of that resulting from conventional processing, and preferably less than 40%, and even more preferably less than 30%.

. The total amount of water consumed in taitings may be reduced to less than 50% of those resulting from conventional processing, and preferably less than 40%, and even more preferably less than 30%.

Claims (22)

1. An integrated process for recovering value metals from sulphide ore, including the steps of: a) obtaining a crushed ore; b) bulk sorting and screening the d ore to provide a /screened coarse ore stream and a waste ore stream; c) subjecting the sorted/screened coarse ore stream to ng in a mill followed by classification to provide a coarse fraction suitable for coarse flotation and a first fine fraction suitable for conventional flotation; d) subjecting the coarse fraction suitable for coarse flotation to coarse flotation thereby to obtain a gangue and an intermediate concentrate; e) subjecting the intermediate concentrate to grinding to provide a second fine fraction suitable for flotation; and f) subjecting the first fine fraction and the second fine fraction to conventional flotation to provide a concentrate and tailings.

2. The process claimed in claim 1, wherein, at step a), the ore is crushed to a size suitable for presentation on a conveyor, as a feed to grinding stage at step c).

3. The process claimed in claim 2, wherein, at step a), the ore is crushed to a size in the range of 5 to 40 cm.

4. The process claimed in any one of claims 1 to 3, wherein bulk g in step b) is on a bulk sorter comprising a conveyor belt with a diverter mechanism controlled by a continuous is , wherein the diverter mechanism diverts low grade zones of rock which do not meet a selected cut off grade (CoG) to the waste stream.

5. The process claimed in claim 4, wherein the continuous analysis sensor comprises a rapid scanning sensor.

6. The process claimed in claim 5, n the sensor is a magnetic resonance or neutron activation or an X-ray sensor.

7. The process claimed in any one of claims 4 to 6, wherein the cut off grade (CoG) is determined from geo-statistical analysis of drill core from the source of the ore.

8. The process claimed in any one of claims 1 to 7, wherein, at step b), the crushed ore is ted to bulk g followed by screening or screening followed by bulk sorting.

9. The process claimed in any one of claims 1 to 8, wherein, at step b), the crushed ore is subjected to bulk sorting to provide a sorted coarse ore stream, which is subjected in to grinding in step c), and a first waste ore stream.

10. The process d in claim 9, wherein the sorted coarse ore stream is screened to e a screened coarse ore stream, which is subjected to grinding in step c), and a second waste ore .

11. The process claimed in claim 10, wherein the size of screen apertures of a screen used to screen the coarse ore stream are selected to provide a screened coarse ore stream that is about 80- 90% by weight of the coarse ore stream from bulk sorting.

12. The process claimed in claim 10 or 11, wherein, at step b), the first waste stream is screened to provide a third waste ore stream and a higher grade fraction that is sent for grinding in the grinder at step c) er with the sorted/screened ore stream.

13. The process claimed in claim 12, wherein the size of screen apertures of a screen used to screen the first waste ore stream are selected to r from 15-25% by weight of the stream.

14. The process d in any one of claims 1 to 13, wherein, at step c), the ore is ground and classified to separate a size of less than 1000 micron.

15. The process claimed in any one of claims 1 to 14, wherein, at step c), the ore is ground in closed loop with a classification t such that material that is already reduced to the appropriate size ranges for coarse and conventional flotation can be scalped.

16. The process claimed in claim 15, wherein, at step c), the ore is subjected to fication to provide a coarse fraction suitable for coarse flotation with a size range of 100 µm up to 1000 µm, and a first fine fraction suitable for conventional flotation with a size of less than 100 µm.

17. The process claimed in claim 16, wherein, at step c), the ore is subjected to classification to provide a coarse fraction suitable for coarse flotation with a size range of 150 µm up to 1000 µm, and a first fine fraction suitable for conventional flotation with a size of less than 150 µm.

18. The process claimed in claim 17, wherein, at step c), the ore is subjected to classification to provide a coarse on le for coarse flotation with a size range of 200 µm up to 1000 µm, and a first fine fraction suitable for conventional flotation with a size of less than 200 µm.

19. The process claimed in any one of claims 1 to 18, wherein, at step e), the intermediate concentrate is ground a size of less than 150 µm to provide a second fine fraction suitable for conventional flotation.

20. The process claimed in any one of claims 1 to 19, in which natural grade recovery curves are ined for the ore, and each of the following ciation steps: iv) bulk sorting; v) screening; vi) coarse flotation; is arranged and controlled to permanently reject the maximum quantity of waste at a grade less than an economic f-grade.

21. The process claimed in claim 20, in which the beneficiation steps iv) bulk sorting; v) screening; vi) coarse flotation; are further arranged and controlled to also te a low grade ore suitable for stockpiling or heap leaching, and hence produce a high grade feed to fill the available comminution and conventional flotation capacity.

22. The process as claimed in claim 1, substantially as herein described with reference to any one of the