A metal-containing material processing operation

Abstract

A processing operation for processing a metal-containing material, comprising at least one of (i) a heap leach circuit that leaches a metal from a metal-containing material with a leach solution and produces a pregnant leach solution, the circuit including a metal recovery unit that recovers the metal from the pregnant leach solution and (ii) a concentrator circuit that forms a metal-containing concentrate from a comminuted metal-containing material; a pH treatment unit that adjusts the pH of at least one of a heap leach effluent stream and a concentrator effluent stream, and forms at least one pH-adjusted effluent stream, wherein the heap leach effluent stream is produced by the heap leach circuit of the processing operation or a different heap leach circuit and the concentrator effluent stream is produced by the concentrator circuit of the processing operation or a different concentrator circuit; and at least one effluent storage unit that receives and stores the at least one pH-adjusted effluent stream, and forms process water that is used in at least one of the heap leach circuit and the concentrator circuit of the processing operation.

Description

[0001] A METAL-CONTAINING MATERIAL PROCESSING OPERATION

[0002] FIELD OF INVENTION

[0003] The present invention relates to a processing operation and a method for processing a base metal-containing material or a precious metal-containing material and recovering a resource, such as water or heat, from one part of the processing operation and using the resource in another part of the processing operation, where the term “material” comprises, for example, ore and waste material such as tailings and mineralised waste.

[0004] The present invention relates particularly, although by no means exclusively, to a processing operation and a method for processing a base metal-containing material or a precious metal-containing material, for recovering a base metal, such as copper or nickel or zinc or cobalt, or a precious metal, such as gold or silver, where the term “material” comprises, for example, ore and waste material such as tailings and mineralised waste.

[0005] The term “processing operation” is understood herein to include any processing unit or any combination of processing units at a mine site that contribute to processing a material containing either or both a base metal and a precious metal-to recover at least one of the base metal and precious metal. It is understood that the metal produced in a processing operation may need further processing to be in a required end use form for the metal. This further processing may be undertaken at a location other than the mine site. For example, the processing operation may produce a metal-containing concentrate that requires further processing off-site, for example in a smelter, to recover metals in an enduse form.

[0006] The term “mine site” is understood herein to be a broad term that covers, by way of example only, a site in which there is (i) an area (above and / or below ground) being mined, with material being removed from the area, (ii) an area (above and / or below ground) that has been mined, with material already removed from the area, (iii) stockpiles of mined material from areas (i) and (ii), and / or (iv) downstream processing units including, for example, any one or more of: a comminution circuit for comminuting mined material (such as crushers and grinding mills) and size separation units for separating mined and comminuted mined material based on size, a concentrator circuit including for example flotation cells for producing a concentrate-containing the metal and a concentrator effluent stream, a recovery circuit for recovering the metal from the concentrate from the concentrator circuit, a heap leach circuit for producing a pregnant leach solution, the heap leach circuit including for example heap leach pads, equipment for forming heaps on the pads, circuits for supplying leach solution to heaps and recovering pregnant leach solution from heaps, a recovery circuit for recovering the metal from the pregnant leach solution including solvent extraction and electrowinning units, with solvent extraction producing a raffinate, and a unit for regenerating and recycling the raffinate to the heap leach circuit, and storage units such as for reagents, water, pregnant leach solution, concentrates of valuable metals, and effluent streams.

[0007] The present invention further relates particularly, although by no means exclusively, to a mining operation comprising multiple processing operations, each for processing a material containing either or both a base metal and a precious metal to recover at least one of the base metal and precious metal, and further where a resource, such as water or heat, is recovered from one processing operation and used in another processing operation.

[0008] BACKGROUND OF THE INVENTION

[0009] Metals are increasingly becoming important for the transition to a low carbon-based global economy, for example, for the manufacture of hybrid and electric vehicles. Copper is one such metal that facilitates this transition.

[0010] There are substantial capital and operating cost pressures on mine operators of well- established and new copper mines that have low average concentrations of copper in copper sulfide-containing materials or are in cold regions or regions that have large temperature fluctuations.

[0011] Mining companies are also very conscious of the importance of operating mines with minimal environmental impact over short and longer terms and this has an impact on mining options and costs.

[0012] There are several established methods of recovering copper from the copper sulfide- containing materials such as ores and concentrates including heap leaching, tank leaching, pressure leaching, dump leaching, and froth flotation.

[0013] Water is a key resource for most processing methods and is particularly critical in arid regions and remote locations with poor infrastructure. Heat is another resource that is often required to increase leaching rates, particularly for mining operations in cold regions and / or high altitude locations.

[0014] Heap leaching and flotation circuits typically produce large volumes of waste which is typically sludge from the heap leaching circuit and tailings from the flotation circuit. The waste material is usually in the form of aqueous slurries of particulates. In a heap leaching operation, the waste material is typically dewatered to an extent before being transferred to a tailings dam. The waste material may be stored in the tailings dam for long periods of time during an operating life of a mine and after the mine site is closed and is being rehabilitated.

[0015] It is desirable to provide a processing operation and method that recovers a metal from a metal-containing material that reduces demand and maximizes utilization of natural resources.

[0016] The above description is not an admission of the common general knowledge in Australia or elsewhere.

[0017] SUMMARY OF THE INVENTION The present invention provides a processing operation for processing a metal-containing material, comprising: at least one of (i) a heap leach circuit that leaches a metal from a metal-containing material with a leach solution and produces a pregnant leach solution, the circuit including a metal recovery unit that recovers the metal from the pregnant leach solution and (ii) a concentrator circuit that forms a metal-containing concentrate from a comminuted metal-containing material; a pH treatment unit that adjusts the pH of at least one of a heap leach effluent stream and a concentrator effluent stream, and forms at least one pH-adjusted effluent stream, wherein the heap leach effluent stream is produced by the heap leach circuit of the processing operation or a different heap leach circuit and the concentrator effluent stream is produced by produced by the concentrator circuit of the processing operation or a different concentrator circuit; and at least one effluent storage unit that receives and stores the at least one pH- adjusted effluent stream, and forms process water that is used in at least one of the heap leach circuit and the concentrator circuit of the processing operation.

[0018] The processing operation may comprise the heap leach circuit and the concentrator circuit.

[0019] The effluent storage unit may form process water that is used in a circuit that is different to the circuit from which the process water was formed.

[0020] The pH treatment unit may adjust the pH of a heap leach effluent stream and form a pH- adjusted effluent stream. Suitably, an effluent storage unit receives and stores the pH- adjusted effluent stream for use as process water in the concentrator circuit of the processing operation. In one embodiment, the heap leach effluent stream is formed from the heap leach circuit of the processing operation. In another embodiment, the heap leach effluent stream is formed from a heap leach circuit that does not form part of the processing operation, for example a heap leach circuit from a different mine site or a mine site owned by a different company. The pH treatment unit may adjust the pH of a concentrator effluent stream and form a pH-adjusted effluent stream. Suitably, an effluent storage unit receives and stores the pH- adjusted effluent stream for use as process water in the heap leach circuit of the processing operation. In one embodiment, the concentrator effluent stream is formed from the concentrator circuit of the processing operation. In another embodiment, the concentrator effluent stream is formed from a concentrator circuit that does not form part of the processing operation, for example a concentrator from a different mine site or a mine site owned by a different company.

[0021] The pH treatment unit may adjust the pH of a heap leach effluent stream and a concentrator effluent stream and form a pH-adjusted effluent stream. Suitably, an effluent storage unit receives and stores the pH-adjusted effluent stream for use as process water in the concentrator circuit of the processing operation. Suitably, at least one of the heap leach effluent stream and the concentrator effluent stream is formed from a circuit of the processing operation.

[0022] The pH treatment unit may adjust the pH of a heap leach effluent stream and a concentrator effluent stream and form a pH-adjusted effluent stream. Suitably, an effluent storage unit receives and stores the pH-adjusted effluent stream for use as process water in the heap leach circuit of the processing operation. Suitably, at least one of the heap leach effluent stream and the concentrator effluent stream is formed from a circuit of the processing operation.

[0023] The pH treatment unit may adjust the pH of a heap leach effluent stream and a concentrator effluent stream and forms a pH-adjusted effluent stream. Suitably, an effluent storage unit receives and stores the pH-adjusted effluent stream for use as process water in both the heap leach and concentrator circuits of the processing operation. Suitably, at least one of the heap leach effluent stream and the concentrator effluent stream is formed from a circuit of the processing operation.

[0024] The pH treatment unit may adjust the pH of a heap leach and a concentrator effluent stream and forms a pH-adjusted heap leach effluent stream and a pH-adjusted concentrator effluent stream. Suitably, a first effluent storage unit receives and stores the pH-adjusted heap leach effluent stream and a second effluent storage unit receives and stores the pH-adjusted concentrator effluent stream for use as process water in at least one of the heap leach and concentrator circuits of the processing operation. Suitably, at least one of the heap leach effluent stream and the concentrator effluent stream is formed from a circuit of the processing operation.

[0025] From a terminology perspective, “pregnant leach solution” is a generally well-understood term for a metal-containing leach solution that is collected from a heap and transferred to metal recovery. The metal-containing leach solution may be transferred directly to metal recovery or stored temporarily in one or more storage units. Other process solutions and make-up chemicals may be added to these storage units.

[0026] The metal recovery unit of the heap leach circuit may comprise a solvent extraction and electrowinning circuit that produces electrowon metal.

[0027] The term “electrowinning” is understood herein to mean a process that results in the metal depositing on a cathode from a metal bearing solution by the passage of an electric current using an insoluble anode. The metal-containing product is typically described as a “cathode”.

[0028] The metal recovery unit of the heap leach circuit may comprise a precipitation tank for precipitating the target metal from the pregnant leach solution. The precipitation tank is particularly useful to recover nickel.

[0029] Alternatively, or in addition, the processing operation may comprise a metal recovery unit for recovering the metal from the metal-containing concentrate.

[0030] The leach solution may be an acidic leach solution, and the heap leach circuit may produce an acidic heap leach effluent stream.

[0031] The term “acidic leach solution” is understood herein to mean any solution that contains a high concentration of protons and has a pH of less than 7. The solution may be obtained from any suitable source or combination of sources. One source may comprise water from mine site run-off, tailings dam solutions and reclaim, acid mine drainage liquors, mine water, bleed streams. These sources may or may not be associated with the mining operation. Another source may be a raffinate from a solvent extraction circuit for recovering copper from a pregnant leach solution. These sources may not be acidic and may require addition of a suitable acid to produce the acidic leach solution.

[0032] An example of a suitable acid is sulfuric acid (H2SO4).

[0033] The acid may be any other suitable mineral acid or a suitable organic acid.

[0034] The term “acidic heap leach effluent stream” is understood herein to mean an aqueous stream having a pH of less than 7.

[0035] The concentrator effluent stream may be a neutral or alkaline effluent stream.

[0036] The term “neutral or alkaline effluent stream” is understood herein to mean an aqueous stream having a pH of at least 7.

[0037] The metal-containing material may contain either or both a base metal and a precious metal. Suitably, the metal-containing material is a base metal sulfide-containing material.

[0038] Examples of base metals include copper, nickel, zinc and cobalt.

[0039] When the metal is copper, the base metal-containing material may be a copper sulfide- containing material.

[0040] The copper sulfide-containing material may comprise copper-containing material that contains primary and secondary copper sulfide-containing minerals such as chalcopyrite (CuFeS2), enargite (CU3ASS4), tetrahedrite ((Cu,Fe,Zn,Ag)i2Sb4Si3), tennantite (CU12AS4S13), bornite (CusFeS^, chalcocite (C S), covellite (CuS), emplectite (CuBiS2), or any combination thereof and other similar copper sulfide-containing minerals.

[0041] Suitably, the copper sulfide-containing material is chalcopyrite. Examples of precious metals include gold and silver.

[0042] The metal-containing material may be an ore.

[0043] The term “ore” is understood herein to mean natural rock or sediment that contains one or more valuable metals that can be mined, reclaimed, treated and sold at a profit. It is noted that the term “ore” is a relative term in that a material may be regarded as an ore, i.e., profitable at one point in time, and a waste material at another point in time. It is also noted that an assessment of whether a material is an “ore”, i.e., profitable, can also be dependent on the mine from which the material is mined, the operator of the mine, and relatedly the capital and operating costs of the mine, including whether the mine is a brownfield or greenfield mine, and the metal value being extracted or produced.

[0044] Examples of ores include, but are not limited to, (a) run-of-mine (ROM) ore and (b) ROM ore that has been subjected to at least primary crushing or similar or further size reduction after the material has been mined and prior to being sorted. The ore may also include agglomerates of crushed ores. Suitably, the agglomerates may also include the addition of non-ore material.

[0045] The metal-containing material may be waste material, such as tailings or mineralised waste, that is uneconomic to process using current processes.

[0046] The invention was made as part of a research and development project of the applicant on leaching copper from copper-containing material, particularly copper sulfide minerals such as chalcopyrite (CuFeS2).

[0047] One focus of the research and development project is on providing a processing operation and a method that recovers a resource from one part of a mining operation for use in another part of the processing operation, suitably at the same mine site.

[0048] Another focus of the research and development project is on providing a metal recovery operation that directs a resource from either a heap leaching circuit or a concentrator circuit such as a flotation circuit for processing a metal-containing material and recovering metal from the material to the other circuit.

[0049] There are challenges commissioning a processing operation with both circuits, particularly when the metal-containing material is a base metal.

[0050] Firstly, in the context of copper as the base metal, a skilled person would recognise the inherent incompatibility of heap leaching and froth flotation circuits due to their different operating conditions in which copper heap leaching typically operates on crushed ore (Pso <25 mm) in an acidic environment while copper froth flotation typically operates on ground ore (Pso <1 mm) in a neutral to alkaline environment.

[0051] Second, in the context of copper as the base metal, as a result of the different operating conditions, effluent streams from each circuit are expected to be incompatible such that undesirable reactions such as precipitation of metal-containing compounds are likely to occur if mixed. In such a scenario, a skilled person would recognise that the different effluent streams have to be stored separately.

[0052] The applicant has developed a processing operation that includes a pH treatment unit for adjusting the pH of at least one of the effluent streams before the treated effluent stream(s) is transferred into a single effluent storage unit without undesirable reactions of the type mentioned above.

[0053] The pH treatment unit allows a build-up of impurities to be controlled and provides a means of co-impoundment of what is essentially waste material such as sludge or tailings from the heap leach circuit and the concentrator circuit.

[0054] In this specification, the term “pH adjustment” includes adjusting the pH of the effluent stream to any pH from 1-14. For example, the pH of a heap leach stream containing elevated magnesium may be adjusted to about 10.5, suitably using lime, to reduce the magnesium concentration. Similarly, an alkaline concentrator effluent may be lowered to a pH of about 1.2- 1.5 for use in typical heap leach circuits. The term “pH adjustment” also includes lowering the pH of an acidic solution and increasing the pH of an alkaline solution, for example to selectively precipitate impurities.

[0055] The term “pH adjustment” also encompasses neutralization. In this specification, the terms “neutralise” and “neutralisation” include adjusting the pH of the effluent stream towards 7. It is unnecessary for the present invention that the final pH of the effluent stream is or about 7. However, these terms capture embodiments whereby the final pH of the effluent stream is or about 7. For example, neutralisation may include increasing the pH of an acidic environment or decreasing the pH of an alkaline environment. It follows that the term “neutralised” stream may not have a final pH of around 7. For example, a stream having an initial pH of 2 being treated with a base to raise its pH to 5 is considered to be a “neutralised” stream. Similarly, a stream having an initial pH of 10 being treated with an acid to lower its pH to 8 is also considered to be a “neutralised” stream.

[0056] The pH treatment unit may neutralise at least one of the effluent streams. Suitably, the pH treatment unit neutralises at least one of the effluent streams to form at least one effluent stream having a pH of around 7.

[0057] In this specification, the terms “neutralise” and “neutralisation” include adjusting the pH of the effluent stream towards 7. It is unnecessary for the present invention that the final pH of the effluent stream is or about 7. For example, neutralisation may include increasing the pH of an acidic environment or decreasing the pH of an alkaline environment.

[0058] Heap leach and concentrator operation

[0059] In general, the processing operation recovers and recycles process water from an effluent stream from either or both of the heap leach circuit and the concentrator circuit.

[0060] For example, recovered water can be returned as process water to the concentrator circuit. For example, recovered water can be returned as part of a raffinate of the heap leach circuit.

[0061] The heap leach circuit and the concentrator circuit may be located on a mine site.

[0062] Both circuits may be simultaneously operational.

[0063] Both circuits may be operational at different times.

[0064] For example, the present invention encompasses a scenario in which an operational concentrator circuit receives a resource in the form of process water from an effluent storage unit containing effluent from either an operational or a non-operational heap leach circuit.

[0065] The present invention also encompasses a scenario in which an operational heap leach circuit receives a resource in the form of process water from an effluent storage unit from either an operational or a non-operational concentrator circuit.

[0066] Either or both effluent streams may comprise a fluid or a slurry.

[0067] The processing operation may include one or more of primary, secondary and tertiary crushers and grinding mills to process mined metal-containing material for either or both the heap leaching and concentrator circuits, for example to produce the comminuted metal-containing material for the concentrator circuit.

[0068] Depending on requirements, the heap leach circuit may be configured to process ROM material. The ROM material may have been subjected to intermediate processing.

[0069] The term “intermediate processing” relates to any type of processing of ROM material including processing that falls under the general description of “ore dressing” including but not limited to any one or more of comminution, size separation into different size fractions, sorting by grade of a target metal (e.g., concentration of the metal) into different grade fractions, sorting by other chemical or mineralogical composition of the ROM material (such as a contaminant), sorting by other property of the ROM material, and agglomeration.

[0070] The ROM material may be obtained from any mining operation at a mine site.

[0071] The mining operation may be above ground.

[0072] The mining operation may be underground.

[0073] For example, the mining operation may be a drilling and blasting operation in an open pit mine, with the ROM material being rocks that form when a mine bench is drilled and blasted and slumps into a pit and is then transported by haul trucks or other suitable vehicles or conveyors from the pit.

[0074] By way of further example, the mining operation may be an operation involving the use of a continuous miner, with the ROM material being rocks that are produced from the continuous miner.

[0075] By way of further example, the mining operation may be an underground mining operation including block cave mining, sub-level cave mining, or any other suitable underground mining method, with material being removed from extraction points, such as draw points in block cave mines, as metal sulfide-containing material and being transported by haul trucks or other suitable vehicles or conveyors to above-ground.

[0076] By way of further example, the mining operation may be a block caving operation in an underground mine, with the ROM material being rocks in rill piles at draw points of a block cave.

[0077] The metal-containing material may be in any suitable size for the processing operation.

[0078] The metal-containing material rock size may range from coarse to fine depending on other operational considerations. For example, the metal-containing material may have a rock size in a range between a P80 of 500 mm and a P80 of 9 mm, typically in a range between a P80 of 400 mm and a P80 of 30 mm, and typically in a range between a P80 of 100 mm and a P80 of 9 mm.

[0079] It is noted that the rock size of the metal-containing material may be larger or smaller than the above-described size ranges.

[0080] The metal-containing material may be any suitable shape, noting that size ranges described in the preceding paragraph are based on one dimension only.

[0081] The pH treatment unit enables the heap leach effluent stream or the concentrator effluent stream to be processed into a form that is suitable for re-use, and suitably to be supplied to a shared effluent storage unit.

[0082] Typically, combining untreated effluent streams from different sources in the storage unit is expected to cause impurities to precipitate, for example due to a difference in pH of the effluent streams. This would require the fluid in the storage unit to be further treated before it is suitable for use as process water. The present invention provides an opportunity to avoid this by removing the impurities before the treated effluent streams are received by the shared storage unit, for example by adjusting the pH of each effluent stream to precipitate the impurities before the effluent streams are combined.

[0083] In this respect, the pH treatment unit may be configured to treat an effluent stream with an additive such as acid, limestone and lime to alter the pH of the effluent stream. Because the solubility of certain metal ions is affected by pH, the ability of the pH treatment unit to adjust the pH of the effluent stream may enable the effluent stream to be purified by removing one or more impurities before the treated effluent stream is transferred to the effluent storage unit. In one example, magnesium may be precipitated by raising the pH of the effluent stream to about 10.

[0084] Having the ability to alter the pH of the effluent stream also allows both effluent streams to be supplied to a shared effluent storage unit without undesirable side reactions such as precipitation of impurities from occurring in the shared effluent storage unit. Each effluent stream may be processed in a separator such as a thickener that removes solids such as particulate material before the effluent stream is transferred to the effluent storage unit.

[0085] The effluent storage unit may be a tank or a dam or a collection of tanks or dams.

[0086] The effluent storage unit may be a dam for receiving tailings from the concentrator circuit or a tank for receiving sludge from the heap leaching circuit.

[0087] For example, the effluent storage unit may receive a solids-containing underflow of a thickener from the heap leach circuit and / or a solids-containing underflow from a thickener in a concentrator circuit.

[0088] Alternatively, the processing operation may include a plurality of effluent storage units.

[0089] For example, the processing operation may include an effluent storage unit receiving (a) an effluent, such as a solids-containing underflow from a thickener, of the heap leach circuit and (b) an effluent, such as a solids-containing underflow from a thickener, of the concentrator circuit.

[0090] Suitably, the number of effluent storage units is equal to the number of metal-containing material processing circuits in the processing operation.

[0091] For example, the processing operation may include a heap leach circuit effluent storage unit and a separate concentrator circuit effluent storage unit.

[0092] Suitably, the heap leach and the concentrator effluent storage units feed into a combined effluent storage unit.

[0093] In one embodiment, the combined effluent storage unit is configured to receive a pH treated effluent stream from one circuit and a pH untreated effluent stream from the other circuit. The operation may include a raffinate pond to receive an overflow from either or both the heap leach thickener and the concentrator thickener for return to the heap leach circuit as part of the raffinate.

[0094] To improve the purity of the process water, the processing operation may include a purification unit for removing other impurities such as collectors (e.g., xanthates) or selected metal ions such as calcium and magnesium from the reclaimed water of the effluent storage unit.

[0095] The purification unit may include a filter, particularly a nanofilter.

[0096] In some embodiments, a purification unit may be used to treat the overflow from either or both the heap leach thickener and the concentrator thickener.

[0097] The processing operation may be configured to recover heat from one part of the operation, such as from a comminution circuit and / or from a metal recovery circuit, for use in a different part of the operation. The heat may be transferred via fluid transfer using water or gas.

[0098] The processing operation may include one of more heat exchangers to direct heat generated from one circuit to the other circuit.

[0099] Suitable heat sources include solution and slurry streams from the concentrator circuit that can be used to add heat to the heap leach circuit and associated liquor streams.

[0100] The heat source may also be a smelter associated with the operation.

[0101] Heap leach circuit

[0102] The heap leach circuit may perform microbially-assisted aerated leaching of the metalcontaining material. By way of example, when the metal-containing material is copper, the metal mining operation may be directed towards leaching copper from chalcopyrite (CuFeS2). In this example, the microbes oxidise ferrous ions into ferric ions, with the ferric ions and acid solubilising copper in chalcopyrite (and any other copper sulfide-containing minerals in the copper-containing material).

[0103] Oxidants, such as ferric ions, and acid, such as sulfuric acid, are consumed during oxidation of copper sulfide-containing material, and dissolution rates will decrease unless they are replenished.

[0104] Under aerobic conditions, microbes regenerate ferric ions and acid and generate heat through biological oxidation of ferrous ions (such as from pyrite (FeS2) or chalcopyrite (CuFeS2)) and sulfur compounds (including elemental sulfur), as follows:

[0105] 2Fe2++ 2H++ 0.502 2Fe3++ H2O

[0106] 2S + 302 + 2H2O 2H2SO4

[0107] The microbes may be any suitable microbes.

[0108] The microbes may be any microbes that can oxidise ferrous iron and / or sulfur compounds and include, but are not limited to, members of the bacterial genera Acidithiobacillus, Leptospirillum, Sulfobacillus and berrimicrobium. and the archaeal genera Acidianus, Acidiplasma, Ferroplasma, Metallosphaera and Thermoplasma.

[0109] The microbes may be selected from mesophiles, moderate thermophiles and psychrotolerant or mesophilic or thermophilic (moderate or extreme) bacteria or archaea. The microorganisms may be acidophilic bacteria or archaea. The microorganisms may be thermophilic acidophiles. A diverse population allows activity across a range of operating conditions, including low pH conditions, high metal sulfate concentrations, and a wide temperature range of, say, 5-80 °C.

[0110] The sulfur compounds may be derived from oxidation of sulfide minerals (such as pyrite or copper sulfide minerals) or as an addition (such as elemental sulfur, purchased or derived from a biological metal sulfate reduction process) from any source, such as cleaner scavenger tailings from a concentrator circuit.

[0111] Additional material (additives), some of which may include sulfur, may be added to enhance copper dissolution. Examples of such additives include pyrite, sulfur-containing inorganic compounds such as thiosulfate or polythionates or polysulfides, or sulfur- containing organic compounds including thiocarbonyl compounds such as thiourea or other thiocarbamides.

[0112] The additional material may be added to the metal-containing material before the heap is formed, as the heap is being formed, or after the heap has been formed, or to the leach solution.

[0113] The additional material (additives) may be added in any suitable way to the heap.

[0114] For example, the method may comprise adding the additional material (additives) to the metal-containing material in or at any one or more of:

[0115] (a) a location at which the metal-containing material forms in a mining operation (for example slumped material that forms after a mine bench is drilled and blasted);

[0116] (b) a location where metal-containing material is loaded onto haul vehicles (such as haul trucks or load-haul-dump vehicles) or conveyors or any other transport options;

[0117] (c) as the metal-containing material is being transported from a loading location(s) in the mine to a heap, a stockpile, or an intermediary station, or from the stockpile or the intermediary station to the heap;

[0118] (d) during agglomeration of the metal-containing material;

[0119] (e) as the metal-containing material is being added to the heap;

[0120] (f) at an intermediary station located between the loading location(s) and the heap;

[0121] (g) at an intermediary station located between the stockpile and the heap;

[0122] (h) in a blending operation comprising blending together the metal-containing material and additional pyrite and then adding the blend to the heap;

[0123] (i) in the stockpile; and (j) in the heap, for example in a leach solution or directly as a separate additive as the heap is being formed or after the heap has been formed, such as to a top of the heap during the heap leaching step.

[0124] For copper sulfide-containing materials:

[0125] (a) during mineral dissolution that releases copper into solution, ferric ions are reduced to ferrous ions, and elemental sulfur and / or sulfuric acid is produced, and

[0126] (b) microbes, when present under aerobic conditions, oxidise ferrous ions to ferric ions, and oxidise available solid and soluble sulfur compounds and generate sulfuric acid.

[0127] In summary, sulfur oxidation generates acid and reactions that convert ferrous ions to ferric ions consume acid.

[0128] The heap leach circuit may comprise a heap of the metal-containing material, a circuit supplying the leach solution to the heap and recovering the pregnant leach solution from the heap, and the metal recovery unit recovering the metal from the pregnant leach solution and producing the raffinate,

[0129] In this embodiment, the pH treatment unit treats the raffinate by adjusting the pH of the raffinate and produces the pH adjusted effluent stream.

[0130] The pH treatment unit may include a thickener that thickens the pH adjusted effluent stream and produces a thickened pH adjusted effluent stream as an underflow stream and a treated raffinate as an overflow stream.

[0131] The heap leach circuit includes a unit for regenerating and recycling the treated raffinate to the heap leach circuit.

[0132] The metal recovery unit may comprise a solvent extraction unit and an electrowinning unit for producing electrowon metal. Concentrator circuit

[0133] The concentrator circuit may utilize separation methods including froth flotation, gravity concentration, electrostatic separation, and magnetic separation to recover metal values.

[0134] Suitably, the concentrator circuit is a froth flotation circuit.

[0135] The concentrator circuit may comprise at least one or more of a crusher, a grinding mill, a rougher flotation cell, a cleaner / scavenger cell, and a thickener.

[0136] The concentrator thickener may be configured to separate solids from the effluent stream from the concentrator circuit and form an overflow that can be repurposed as process water for the concentrator circuit or as make up water for a raffinate stream of the heap leach circuit.

[0137] The concentrator circuit may include a dedicated pH treatment unit or may share a pH treatment unit with the heap leach circuit.

[0138] The concentrator circuit thickener may supply thickener underflow to an effluent storage unit.

[0139] The effluent storage unit may be a dedicated concentrator effluent storage unit or a combined effluent storage unit.

[0140] The present invention also provides a method of recovering a metal from a metalcontaining material using the previously described processing operation.

[0141] The present invention also provides a method of processing a metal-containing material including:

[0142] (a) performing at least one of (i) heap leaching a metal-containing material using a leach solution and producing a pregnant leach solution, recovering a metal from the pregnant leach solution and producing a heap leach effluent stream, and (ii) forming a metal-containing concentrate from a comminuted metal-containing material and producing a concentrate effluent stream; (b) adjusting the pH of at least one of a heap leach effluent stream and a concentrator effluent stream, and forming at least one pH adjusted effluent stream; and

[0143] (c) forming process water from the at least one pH-adjusted effluent stream for use as process water in step (a).

[0144] The method may include a step of directing the process water to a circuit that is different to the circuit from which the process water is formed.

[0145] Step (a) may comprise both heap leaching a metal-containing material using a leach solution and producing a pregnant leach solution, recovering a metal from the pregnant leach solution and producing a heap leach effluent stream and forming a metalcontaining concentrate from a comminuted metal-containing material and producing a concentrate effluent stream.

[0146] Step (b) may include adjusting the pH of a solvent extraction effluent stream.

[0147] Step (b) may include adjusting the pH of the heap leach effluent stream and forming a pH-adjusted effluent stream for use in the metal-containing concentrate forming step. Suitably, step (c) includes forming process water from the pH-adjusted effluent stream for use in the forming of a metal-containing concentrate.

[0148] In one embodiment, the heap leach effluent stream is formed from the heap leach circuit of the processing operation. In another embodiment, the heap leach effluent stream is formed from a heap leach circuit that does not form part of the processing operation, for example a heap leach circuit from a different mine site or a mine site owned by a different company.

[0149] Step (b) may include adjusting the pH of the concentrator effluent stream and forming a pH-adjusted effluent stream for use in the heap leaching step. Suitably, step (c) includes forming process water from the pH-adjusted effluent stream for use in the heap leaching of a metal-containing material. In one embodiment, the concentrator effluent stream is formed from the concentrator circuit of the processing operation. In another embodiment, the concentrator effluent stream is formed from a concentrator circuit that does not form part of the processing operation, for example a concentrator circuit from a different mine site or a mine site owned by a different company.

[0150] Step (b) may include adjusting the pH of both heap leach and concentrator effluent streams and forming a pH adjusted effluent stream for use in the metal-containing concentrate forming step. Suitably, step (c) includes forming process water from the pH- adjusted effluent stream for use in the forming of a metal-containing concentrate. More suitably, at least one of the heap leach effluent stream and the concentrator effluent stream is formed from a circuit of the processing operation.

[0151] Step (b) may include adjusting the pH of both heap leach and concentrator effluent streams and forming a pH adjusted effluent stream for use in the heap leaching step. Suitably, step (c) includes forming process water from the pH-adjusted effluent stream for use in the heap leaching of a metal-containing material. More suitably, at least one of the heap leach effluent stream and the concentrator effluent stream is formed from a circuit of the processing operation.

[0152] Step (b) may include adjusting the pH of both heap leach and concentrator effluent streams and forming a pH adjusted effluent stream for use in both the heap leaching and metal-containing concentrate forming steps. Suitably, step (c) includes forming process water from the pH-adjusted effluent stream for use in both the heap leaching of a metalcontaining material and the forming of a metal-containing concentrate. More suitably, at least one of the heap leach effluent stream and the concentrator effluent stream is formed from a circuit of the processing operation.

[0153] Step (b) may include adjusting the pH of both heap leach and concentrator effluent streams and forming a pH-adjusted heap leach effluent stream and a pH-adjusted concentrator effluent stream for use in either or both the heap leaching and metalcontaining concentrate forming steps. Suitably, step (c) includes forming process water from the pH-adjusted heap leach effluent stream and the pH-adjusted concentrator effluent stream for use in at least one of heap leaching of a metal-containing material and the forming of a metal-containing concentrate. More suitably, at least one of the heap leach effluent stream and the concentrator effluent stream is formed from a circuit of the processing operation.

[0154] The leach solution may be an acidic leach solution, and the heap leach circuit may produce an acidic heap leach effluent stream.

[0155] The concentrator effluent stream may be a neutral or alkaline effluent stream.

[0156] The term “neutral or alkaline effluent stream” is understood herein to mean an aqueous stream having a pH of at least 7.

[0157] The metal-containing material may contain either or both a base metal and a precious metal.

[0158] The metal-containing material may be a base metal-containing material.

[0159] The metal-containing material may be a precious metal-containing material.

[0160] The method may comprise selecting a mining method to form the metal-containing material in a suitable form, including size distribution and / or shape, for either or both the heap leach circuit or the concentrator circuit.

[0161] The method may include a size reduction step to form a comminuted metal-containing material and processing the comminuted metal-containing material in at least the concentrator circuit.

[0162] Suitably, the method includes comminuting the metal-containing material in at least one of primary, secondary and tertiary crushing, and grinding and forming a comminuted material. The method may include transferring the comminuted material to either or both a heap leaching and a metal-containing concentrate forming step.

[0163] When step (a) includes a step of heap leaching a metal-containing material, step (a) may further include operating a microbially-assisted heap leach of the metal-containing material.

[0164] Suitably, the method includes aerating the heap of metal-containing material.

[0165] When step (a) includes a step of heap leaching a metal-containing material, step (a) may further include leaching copper from a heap of chalcopyrite (CuFeS2)-containing material.

[0166] When step (a) includes a step of heap leaching a metal-containing material, step (a) may further include heap leaching ROM base metal-containing ore.

[0167] When step (a) includes a metal-containing concentrate forming step, step (a) may further include separation steps including froth flotation, gravity concentration, electrostatic separation, and magnetic separation to recover metal values.

[0168] Suitably, the separation step includes froth flotation.

[0169] More suitably, the metal-containing concentrate forming step is part of a crush-grind- float process.

[0170] When step (a) includes a step of heap leaching a metal-containing material, step (a) may further include transferring the concentrator effluent stream to a concentrator thickener and forming a solids-containing underflow and an overflow.

[0171] When step (a) includes a step of heap leaching a metal-containing material, step (a) may further include transferring at least a part of the overflow from the concentrator thickener to a raffinate pond. When step (a) includes a step of heap leaching a metal-containing material, step (a) may further include transferring at least a part of the underflow from the concentrator thickener to an effluent storage unit.

[0172] When step (a) includes a step of heap leaching a metal-containing material, step (a) may further include returning part of the overflow from the concentrator thickener as process water to the concentrator unit.

[0173] The pH treatment of at least one of the effluent streams may include mixing of at least one of the effluent streams with an additive such as acid, limestone or lime (or more than one of these additives).

[0174] Suitably, the pH treatment includes mixing the acidic effluent stream with a pH adjustment agent such as limestone, lime or surface oxides.

[0175] In one example, the pH treatment may include raising the pH of the effluent stream to precipitate magnesium.

[0176] Step (b) may include increasing the pH of the effluent stream or decreasing the pH of the effluent stream without the final pH necessarily being 7 to form a pH adjusted effluent stream.

[0177] Step (b) may include adjusting the pH of the effluent stream to removing sulfates.

[0178] Suitably, the effluent stream is the raffinate from the heap leach circuit.

[0179] Step (b) may include treating the effluent stream to remove calcium.

[0180] Suitably, step (b) includes mixing the acidic effluent stream with an acid to remove the calcium.

[0181] If necessary, the pH treated effluent stream may be purified using other techniques such as nanofiltration to remove other impurities. The method may include transferring at least one of the effluent streams to a thickener to remove solids such as particulate matter and forming an overflow suitable for reuse by the operation. Either or both the effluent streams may be pH treated before being transferred to the thickener.

[0182] The method may include transferring at least one of the effluent streams into an effluent storage unit. The method may include directly transferring the effluent stream into the effluent storage unit or indirectly transferring the effluent stream into the effluent storage unit via a thickener. Suitably, the method includes transferring an underflow from the heap leach circuit thickener to the effluent storage unit.

[0183] The method may include transferring two effluent streams into separate effluent storage units, with one effluent stream to one effluent storage unit and the other effluent stream to another effluent storage unit. Suitably, the method includes transferring liquor from the heap leach and concentrator effluent storage units into a combined effluent storage unit. In one embodiment, the method includes mixing a pH treated liquor from one circuit with an untreated liquor from the other circuit in the combined effluent storage unit.

[0184] The method may include reclaiming water from the effluent storage unit as process water stream and transferring reclaimed water to one of the heap leaching or the concentrate forming steps.

[0185] Suitably, the method includes dewatering the waste material in the effluent storage unit to reclaim liquor as the process water stream.

[0186] The method may include transferring an overflow from either or both the heap leach and concentrator thickeners to a raffinate pond. The raffinate pond provides a raffinate reservoir for heap leaching of the base metal-containing material.

[0187] The method may include removing other impurities such as collectors (e.g., xanthates) or selected metal ions such as calcium and magnesium from the reclaimed water. Suitably, the method includes filtering the reclaimed water, preferably using a nanofilter. More suitably, the method includes treating the overflow from either or both the heap leach and concentrator thickeners.

[0188] The method may include supplementing either or both the raffinate pond and process water with externally sourced water. Suitably, the externally sourced water is untreated.

[0189] The method may include transferring heat generated from one circuit to the other circuit.

[0190] The method may include using one of more heat exchangers to transfer heat generated from one circuit to the other circuit.

[0191] Suitably, the method includes using heat generated in the heap leach circuit to heat one or more process streams of the concentrator circuit.

[0192] For example, warm solution from the heap leach may help with frozen tailings dams in winter.

[0193] Excess heat from the heap leach may also be adsorbed into the overall water balance as a pre-cooling option for the pregnant leach solution prior to solvent extraction.

[0194] In another example, warm solution from the concentrator may be used as a heat source to pre-heat leach solution, particularly in winter.

[0195] The invention also relates to end use products made from the metal recovered from the metal recovery unit of the heap leach circuit or the metal recovery unit for the metalcontaining concentrate.

[0196] The end use products may be any suitable end use products.

[0197] As noted above, electrowinning a metal produces a product described as a “cathode”. The cathode is a form of an end-use product in that it is a marketable product that can be sold to downstream manufacturers to be processed into other end-use products. For example, the cathode may be processed in any suitable way to produce other end-use products, including billets, ingots, bars, and tubes.

[0198] The other end-use products may comprise the following categories of products: Semi-fabricated products: including copper wire rods for the wire and cable industry.

[0199] - Power Generation: including electrical conductors, transformers, wires, and cables.

[0200] Construction: including plumbing, roofing, and architectural elements.

[0201] - Electronics: including printed circuit boards (PCBs), wiring, and semiconductors.

[0202] Automotive Industry: radiators, connectors, and wiring. Telecommunications: including communication networks.

[0203] Copper alloys such as brass and bronze that are widely used in various applications due to their unique properties such as high strength, corrosion resistance, and aesthetic appeal.

[0204] - Decorative Items: including coins, medals, and other decorative items.

[0205] The end use products may be manufactured by any suitable method.

[0206] BRIEF DESCRIPTION OF DRAWINGS

[0207] An embodiment of the invention is hereinafter described by way of example only with reference to the accompanying drawings, wherein:

[0208] Figure l is a block flow diagram of an operation of recovering a base metal from a base metal-containing material according to one embodiment of the present invention;

[0209] Figure 2 is a process flow sheet of a method of heap leaching copper as disclosed in International patent application PCT / US2021 / 043878; and Figure 3 is a process flow sheet of a method of forming copper concentrate involving crushing, grinding and floating of copper-containing ore.

[0210] DETAILED DESCRIPTION

[0211] A base-metal recovery operation according to one embodiment of the present invention is denoted as 210 in Figure 1.

[0212] The operation includes two different circuits for processing a base metal-containing material - a heap leaching circuit and a concentrator circuit - that generate effluent streams typically in the form of a sludge from the heap leaching circuit and tailings from the concentrator circuit.

[0213] The embodiment shown in Figure 1 treats the effluent streams from either or both the heap leaching circuit and the concentrator circuit and recovers process water that is returned to at least the concentrator circuit for further use.

[0214] The base metal-containing material processed by the heap leaching circuit and the concentrator circuit may be sourced from the same mine site or from different sites. Additionally, the material may be processed by each circuit simultaneously or at different times. The present invention encompasses a scenario whereby water is reclaimed from the effluent storage unit of a non-operational heap leaching plant as process water for use in an operational concentrator at the same or different mine site, and another scenario whereby water is reclaimed from the effluent storage unit of an operational heap leaching plant as process water for an operational concentrator at the same or different mine site.

[0215] The following description of the invention focuses on copper as one example of a metal in a metal-containing material, such as a metal sulfide mineral. Whilst this example is directed towards copper recovery, it is equally applicable to the recovery of other base metals including nickel, zinc and cobalt and to precious metals including gold and silver.

[0216] Figure 2 provides an exemplary method of heap leaching copper as disclosed in International patent application PCT / US2021 / 043878 which is incorporated in its entirety as previously stated. The desired output from this method is copper cathodes 10A from the electrowinning step 10. The main source of effluent material is from the solvent extraction step 9 which is subjected to a limestone / lime neutralization step 11, either in part or full. The bypass stream 9 A enables part of the stream from solvent extraction step 9 to bypass the neutralization step 11. The neutralization step 11 generates neutralized effluent for a separate impoundment in step 12. In some embodiments, the stream from solvent extraction step 9 may be subjected to a pH adjustment step in which the pH of an acidic stream is lowered or an alkaline stream is increased, for example to precipitate impurities from the stream. For example, the pH of a stream having a pH of 8 may be increased to a pH of 10 to remove magnesium.

[0217] The method of Figure 2 primarily comprises two operations. A first operation processes copper sulfide-containing material into a form that is suitable to be agglomerated with pyrite concentrate and a second operation processes waste material in the form of pyritecontaining tailings to recover pyrite. The products from these operations are then mixed to form agglomerates.

[0218] Processing copper sulfide-containing material includes the following steps:

[0219] • Step 1 of mining and delivering copper sulfide-containing material in suitable vehicles, such as haul trucks or front-end loaders, or on conveyor belts to be comminuted to the extent required to produce a suitable particle size distribution for agglomeration. The copper sulfide-containing material may be in the form of waste rock having low grades of copper that has been re-mined from stockpiles.

[0220] • Step 2 of primary and secondary crushing of the copper sulfide material to form a secondary crushed copper sulfide material.

[0221] • Step 3 of tertiary crushing of the secondary crushed copper sulfide material to form tertiary crushed copper sulfide material. Depending on the size of the crushed material, a bypass stream 2A allows some of the crushed material to bypass the tertiary crushing step.

[0222] Processing of the pyrite-containing tailings includes the following steps:

[0223] • Step 15 of pumping the pyrite-containing tailings from a tailings dam or other suitable source of tailings such as directly from an ore processing plant into a cyclone or any other suitable size classification operational unit. • Step 16 of classifying the tailings to form an oversize fraction and an undersize fraction.

[0224] • Step 17 of comminuting the oversize fraction suitably by grinding and polishing in a ball mill to form a comminuted stream that is returned to classification step 16 for further classification.

[0225] • Step 18 of floating the undersize fraction in a first flotation step to form a first underflow inert stream and a first overflow pyrite-containing concentrate stream. The first underflow stream is transferred to a downstream neuralization step 11 and the first overflow pyrite-containing concentrate stream is transferred to and processed in a second flotation step 19.

[0226] • Step 19 of floating the first pyrite-containing concentrate stream to form a second underflow inert tails stream and a second overflow pyrite-containing concentrate stream. A bypass stream 18A allows some of the first overflow pyrite-containing concentrate stream to bypass the second flotation step.

[0227] • Step 20 of thickening and dewatering the second pyrite-containing concentrate stream to form a pyrite concentrate.

[0228] An agglomeration step 4 mixes and agglomerates (i) the pyrite concentrate from step 20 and (ii) copper sulfide-containing material that has been processed in steps 1, 2, 3 in the presence of an acid 4A.

[0229] The formed agglomerates are then conveyed and stacked into a heap in step 5.

[0230] The heap may be any suitable heap construction and may be provided with:

[0231] (a) a leach solution storage and delivery system to supply leach solution to an upper surface of the heap;

[0232] (b) a pregnant leach solution collection system for collecting pregnant leach solution containing copper in solution that is extracted from copper sulfide-containing materials in agglomerates in the heap; and

[0233] (c) microbes (such as bacteria or archaea) or other suitable oxidants to oxidise ferrous iron to ferric iron, with the ferric iron being an oxidant in the leaching process. The heap is then subjected to heap leach step 6 that leaches copper from the heap of copper sulfide-containing agglomerates and produces a pregnant leach solution. To enhance leaching, the heap may be aerated in step 6A.

[0234] The pregnant leach solution from step 6 is then processed in a solvent extraction step 9 that extracts copper from the liquor into an organic medium and then strips copper from the organic medium and produces a copper-containing solution. The copper-containing solution is transferred to an electrowinning step 10 and copper is recovered from the solution in the form of copper cathodes 10A. An electrolyte bleed 8 is provided to enable purging of electrolyte from step 10 and the recycling of electrolyte from the electrowinning step 10 to solvent extraction step 9.

[0235] The raffinate from the solvent extraction step 9 is regenerated and returned to the heap as leach solution. The raffinate may be stored in a storage tank 7 before being returned to the heap. The leach solution regeneration process includes a raffinate limestone / lime neutralization step 11 to control the build-up of impurities, generating a neutralized solid containing stream for separate impoundment in a neutralization residue storage step 12. A neutralised bleed 12A enables fluid from the storage step to be purged.

[0236] Figure 3 provides an exemplary concentrator circuit for forming a copper concentrate.

[0237] The circuit comprises a crusher 101, a primary grinding mill 102, and a secondary grinding mill 103 that comminutes copper-containing ore before a slurry of the comminuted ore is transferred to a rougher flotation cell 104.

[0238] Tailings from the rougher flotation cell 104 are discharged into a tailings dam 110, while a rougher concentrate is re-ground in concentrate grinding mill 105 before being sent to a battery of cleaner / scavenger cells 106A-D to be further concentrated.

[0239] Cleaner cells 106A-C are arranged in series and generate a copper concentrate stream that exits 106C and enters concentrate thickener 107. Tailings from cleaner cell 106A are transferred to cleaner / scavenger cell 106D to recover and return any valuable copper material missed during the rougher flotation cell 104 to the concentrate grinding mill 105. The remaining waste material from this cell would be transferred to tailings dam 110.

[0240] Copper concentrate recovered from the concentrate thickener 107 is dewatered in dewatering unit 108 to form a stockpile of copper concentrate 109 as the desired final product.

[0241] As noted above, the embodiment shown in Figure 1 provides a mining operation comprising both a heap leach circuit and a concentrator circuit that enable water and heat recovered from one circuit to be recycled or used in the other circuit.

[0242] With reference to the examples shown by Figures 2 and 3, the embodiment recovers process water from both circuits, particularly from the solvent extraction stage 9 from the heap leach circuit in Figure 2 and the tailings dam 110 from the concentrator circuit in Figure 3, for use in the concentrator circuit.

[0243] In one example, the operation 210 according to the described embodiment in Figure 1 recovers copper from mined chalcopyrite-containing ore. The ore may be ROM material or agglomerates of ore.

[0244] The operation 210 in Figure 1 includes a heap leach circuit that leaches copper from a chalcopyrite-containing ore with an acidic leach solution in a microbially assisted heap leach, and a concentrator circuit, in the form of a flotation circuit, that forms copper- containing concentrates from comminuted chalcopyrite-containing material. It can be appreciated that other operations according to the present invention involve microbe-free heap leach.

[0245] The heap leach circuit comprises operational units known in the art such as those disclosed in International patent applications PCT / US2021 / 043878 and PCT / US2021 / 043908, the contents of which are incorporated in their entirety.

[0246] In Figure 1, the heap leach circuit comprises a heap of copper-containing material, a solvent extraction unit, and an electrowinning unit, collectively shown as stage 212. The heap leach circuit further includes a pH treatment unit 242, a thickener 216 and a raffinate pond 220.

[0247] The concentrator circuit shown in Figure 1 comprises a flotation circuit 214 that produces a copper-containing concentrate from a comminuted copper-containing material, and a thickener 234.

[0248] The heap leach circuit and the concentrator circuit share an effluent storage unit 224 that receives the underflow from both thickeners 216 and 234. Over time, settling of the underflow from both thickeners occurs and a supernatant comprising water forms over a bed of solids. Depending on the operation, the water can have a pH of up to 10. A pH adjustment step may be performed in either or both thickeners, particularly to ensure that the pH of the underflows 222 and 230 are similar.

[0249] At least a part of the supernatant is withdrawn from the effluent storage unit 224 and becomes reclaimed water streams 225 and 226. The reclaimed water stream 225 and water from an external water source 238 are combined and become process water stream 232, which is used in the concentrator circuit. The reclaimed water stream 226 is used to supplement the raffinate pond 220. It can be appreciated that in other embodiments, reclaimed water stream 226 is optional.

[0250] Turning back to the heap leach circuit, a heap leach effluent stream in the form of a raffinate 240, for example from solvent extraction step 9 of Figure 2, is neutralized in the pH treatment unit 242, such as a neutralization tank, and forms a neutralized raffinate 244 that is subsequently transferred to the thickener 216.

[0251] The neutralized raffinate 244 is purified in the heap leach thickener 216 and forms a substantially liquid overflow stream 218 and a solids-containing underflow stream 222. Overflow stream 218 is transferred to a raffinate pond 220 and underflow stream 222 is transferred to the effluent storage unit 224.

[0252] The raffinate pond 220 is connected to the heap to recycle the overflow 218 as part of the leach solution. With respect to the concentrator circuit, an effluent waste stream 236 produced by the flotation circuit 214 is transferred to a thickener 234, where it is separated into a substantially liquid overflow stream 228 and a solids-containing underflow stream 230. Because the embodiment in Figure 1 comprises a shared effluent storage unit 224, the pH of the effluent waste stream 236 should be suitably adjusted to a pH that is similar to the overflow and underflow streams 218 and 222 exiting thickener 216. In one embodiment, the pH of the effluent waste streams 218, 222 and 236 are adjusted to around pH 7 for use as process water. This minimizes pH fluctuations between the effluent streams and process water.

[0253] The underflow 230 is transferred to the effluent storage unit 224 and combined with the underflow 222 from the heap leach circuit, while the overflow 228B is sent to the raffinate pond 220. If necessary, a part of the overflow 228A can be returned to the flotation circuit as process water 232.

[0254] Due to the operational conditions of the flotation circuit 214, both the overflow stream 228 and the underflow stream 230 from the thickener 234 are usually alkaline. However, the pH of these streams is operation dependent and typically varies from neutral to alkaline.

[0255] It is generally expected that effluent streams from the flotation circuit and the heap leach circuit will need to be transferred to separate effluent storage units (e.g., tailings dams) because of their different pH operating conditions which can cause undesirable reactions to occur when the waste materials are mixed. The embodiment shown in Figure 1 is advantageous over such an arrangement because the pH treatment unit enables a shared effluent storage unit to be used to receive effluent streams from both circuits and reduces the footprint of the mine site.

[0256] This is achievable because of the ability of the pH treatment unit 242 to control the pH of either or both the heap leach and concentrator effluent streams using an additive such as acid, limestone and lime. This allows the individual streams to be (i) purified by removing one or more impurities by manipulating the solution pH and (ii) mixed without significant pH fluctuation or undesirable side reactions such as precipitation of impurities.

[0257] In addition to the recovery and re-use of water produced by both circuits, the operation 210 may also be configured to recover and re-use heat from one part of the operation in another part of the operation. In this respect, a series of heat exchangers may be installed to thermally connect the heap leaching circuit and the concentrator circuit such that heat generated from one circuit may be re-used in the second circuit. For example, heat generated from microbially-assisted aerated heap leaching of chalcopyrite-containing material can be used to heat the hot side of the heat exchanger network to be used by the flotation circuit 214. In another example, tailings from the flotation circuit 214 may be used to cool the pregnant leach solution prior to solvent extraction in stage 212. Heat generated in the flotation circuit 214 may also be used to pre-heat leach solution in cold climates such as during winter.

[0258] One example of a method of recovering a base metal from a base metal-containing material according to one embodiment of the present invention, specifically directed towards recovering copper from chalcopyrite-containing ore, is described below.

[0259] According to the method, the chalcopyrite-containing ore is subjected to a suitable heap leach operation known in the art which can include a microbially-assisted aerated leaching step.

[0260] Due to the nature of the heap leach circuit including the solvent extraction unit, this heap leaching step produces an effluent stream that is an acidic raffinate stream 240, typically including sulfuric acid and having a pH less than 4.

[0261] The acidic raffinate stream 240 typically exits the heap leaching circuit from the solvent extraction unit. This stream 240 is then subjected to a pH treatment step in which a basic additive, such as limestone or lime, is added to increase the pH of the raffinate to control the mineral content of the raffinate. For example, a limestone / lime combination may be used to increase the pH to 10 to selectively precipitate first iron and aluminium at pH 3-4 with limestone and then magnesium at pH 10 with lime in sequential order from solution. The pH treatment step can also be used to remove anions, particularly sulfate, from the raffinate.

[0262] The neutralised effluent stream 244 is then transferred into a thickener 216 to form overflow and underflow streams 218 and 222, respectively.

[0263] The overflow stream 218 is transferred into a raffinate pond 220 which provides a source of leach solution for the heap leach circuit. To manage fluid flow, part of the overflow 218 may be returned to the pH treatment unit 242 via a bleed stream 221. In some embodiments, the overflow 218 may have its pH adjusted before the overflow 218 is returned to the pH treatment unit 242. Taking this step may minimise the release of unwanted elements from solution when overflow 218 is mixed with the solution in the pH treatment unit 242.

[0264] The underflow slurry 222 is transferred into an effluent storage unit 224 that is shared with the concentrator circuit.

[0265] Effluent, which is basically waste material, in the effluent storage unit 224 can be dewatered to recover water as process water 232.

[0266] The operation may include a purification step to remove collectors such as xanthates and some metal ions from the neutralised underflow slurry 222 before it is transferred into the effluent storage unit 224.

[0267] In operation, the flotation circuit 214 generates a typically alkaline effluent waste stream 236 which is transferred into a thickener 234 to remove solids from what is basically a waste stream and form an overflow 228 and underflow 230.

[0268] The overflow 228 is primarily water that can be transferred to the raffinate pond 220 or returned as process water to the flotation circuit 214. Before the overflow is transferred to the raffinate pond or returned to the flotation circuit 214, it may be subjected to a filtration step to remove collectors such as xanthates from the liquor. The underflow 230, in the form of a slurry, is returned to the effluent storage unit 224.

[0269] The effluent in the effluent storage unit 224 is reclaimed as process water for the flotation circuit 214 or raffinate pond 220, as described above.

[0270] If necessary, externally sourced water is used to supplement the raffinate pond 220 or as process water for the heap leach circuit and the concentrator circuit.

[0271] Accordingly, the embodiment of the operation and the method described in relation to the Figures effectively and efficiently shares resources, specifically water from separate heap leach and concentrator circuits and, optionally heat from the circuits.

[0272] Many modifications may be made to the embodiment of the operation and the method described in relation to the Figures without departing from the spirit and scope of the invention.

Claims

CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A processing operation for processing a metal-containing material, comprising: at least one of (i) a heap leach circuit that leaches a metal from a metal-containing material with a leach solution and produces a pregnant leach solution, the circuit including a metal recovery unit that recovers the metal from the pregnant leach solution and (ii) a concentrator circuit that forms a metal-containing concentrate from a comminuted metal-containing material; a pH treatment unit that adjusts the pH of at least one of a heap leach effluent stream and a concentrator effluent stream, and forms at least one pH-adjusted effluent stream, wherein the heap leach effluent stream is produced by the heap leach circuit of the processing operation or a different heap leach circuit and the concentrator effluent stream is produced by the concentrator circuit of the processing operation or a different concentrator circuit; and at least one effluent storage unit that receives and stores the at least one pH- adjusted effluent stream, and forms process water that is used in at least one of the heap leach circuit and the concentrator circuit of the processing operation.

2. The processing operation defined in claim 1 wherein the metal recovery unit of the heap leach circuit comprises a solvent extraction and electrowinning circuit that produces electrowon metal.

3. The processing operation defined in claim 1 or claim 2 further comprises a metal recovery unit for recovering the metal from the metal-containing concentrate.

4. The processing operation defined in any one of the preceding claims wherein the leach solution is an acidic leach solution, and the heap leach circuit produces an acidic heap leach effluent stream.

5. The processing operation defined any one of the preceding claims wherein the pH treatment unit treats at least one of the effluent streams with an additive to alter the pH of the effluent stream(s).

6. The processing operation defined in any one of the preceding claims wherein the pH treatment unit neutralises at least one of the effluent streams.

7. The processing operation defined in any one of the preceding claims comprises processing each of the effluent streams in a separator and removing solids before transferring the effluent streams to the effluent storage unit.

8. The processing operation defined in any one of the preceding claims comprises transferring a solids-containing underflow of a thickener from the heap leach circuit and / or a solids-containing underflow of a thickener of the concentrator circuit to the effluent storage unit.

9. The processing operation defined in any one of the preceding claims, wherein the effluent storage unit forms process water that is used in a circuit that is different to the circuit from which the process water is formed.

10. The processing operation defined in any one of the preceding claims, wherein the pH treatment unit adjusts the pH of a heap leach effluent stream and forms a pH-adjusted effluent stream, and an effluent storage unit receives and stores the pH-adjusted effluent stream for use as process water in the concentrator circuit of the processing operation.

11. The processing operation defined in any one of claims 1 to 9, wherein the pH treatment unit adjusts the pH of a concentrator effluent stream and forms a pH-adjusted effluent stream, and an effluent storage unit receives and stores the pH-adjusted effluent stream for use as process water in the heap leach circuit of the processing operation.

12. The processing operation defined in any one of claims 1 to 9, wherein the pH treatment unit adjusts the pH of a heap leach effluent stream and a concentrator effluent stream and forms a pH-adjusted effluent stream, and an effluent storage unit receives and stores the pH-adjusted effluent stream for use as process water in the concentrator circuit of the processing operation.

13. The processing operation defined in any one of claims 1 to 9, wherein the pH treatment unit adjusts the pH of a heap leach effluent stream and a concentrator effluent stream and forms a pH-adjusted effluent stream, and an effluent storage unit receives and stores the pH-adjusted effluent stream for use as process water in the heap leach circuit of the processing operation.

14. The processing operation defined in any one of claims 1 to 9, wherein the pH treatment unit adjusts the pH of a heap leach effluent stream and a concentrator effluent stream and forms a pH-adjusted effluent stream, and an effluent storage unit receives and stores the pH-adjusted effluent stream for use as process water in both the heap leach and concentrator circuits of the processing operation.

15. The processing operation defined in any one of claims 1 to 9, wherein the pH treatment unit adjusts the pH of a heap leach effluent stream and a concentrator effluent stream and forms a pH-adjusted heap leach effluent stream and a pH-adjusted concentrator effluent stream, and a first effluent storage unit receives and stores the pH- adjusted heap leach effluent stream and a second effluent storage unit receives and stores the pH-adjusted concentrator effluent stream for use as process water in at least one of the heap leach and concentrator circuits of the processing operation.

16. The processing operation defined in any one of the preceding claims comprises recovering heat from one part of the operation and using the heat in a different part of the operation.

17. A method of processing a metal-containing material including:(a) performing at least one of (i) heap leaching a metal-containing material using a leach solution and producing a pregnant leach solution, recovering a metal from the pregnant leach solution and producing a heap leach effluent stream, and (ii) forming a metal-containing concentrate from a comminuted metal-containing material and producing a concentrate effluent stream;(b) adjusting the pH of at least one of a heap leach effluent stream and a concentrator effluent stream, and forming at least one pH adjusted effluent stream; and(c) forming process water from the at least one pH-adjusted effluent stream for use in step (a).

18. The method defined in claim 17 wherein step (a) comprises transferring the concentrator effluent stream to a concentrator thickener and forming a solids-containing underflow and an overflow.

19. The method defined in claim 18 wherein step (a) comprises transferring at least a part of the underflow from the concentrator thickener to an effluent storage unit.

20. The method defined in any one of claims 17 to 19 wherein step (a) includes adjusting the pH of at least one of the effluent streams by mixing the effluent stream with an additive.

21. The method defined in claim 20 wherein step (a) includes neutralizing the heap leach effluent stream.

22. The method defined in any one of claims 17 to 21, including a step of directing the process water to a circuit that is different to the circuit from which the process water is formed.

23. The method defined in any one of claims 17 to 22, wherein step (b) includes adjusting the pH of the heap leach effluent stream and forming a pH-adjusted effluent stream and step (c) includes forming process water from the pH-adjusted effluent stream for use as process water in the forming of a metal-containing concentrate.

24. The method defined in any one of claims 17 to 22, wherein step (b) includes adjusting the pH of the concentrator effluent stream and forming a pH-adjusted effluent stream and step (c) includes forming process water from the pH-adjusted effluent stream for use as process water in the heap leaching of a metal-containing material .

25. The method defined in any one of claims 17 to 22, wherein step (b) includes adjusting the pH of both heap leach and concentrator effluent streams and forming a pHadjusted effluent stream and step (c) includes forming process water from the pH- adjusted effluent stream for use as process water in the forming of a metal-containing concentrate.

26. The method defined in any one of claims 17 to 22, wherein step (b) includes adjusting the pH of both heap leach and concentrator effluent streams and forming a pH adjusted effluent stream and step (c) includes forming process water from the pH- adjusted effluent stream for use in the heap leaching of a metal-containing material.

27. The method defined in any one of claims 17 to 22, wherein step (b) includes adjusting the pH of both heap leach and concentrator effluent streams and forming a pH adjusted effluent stream, and step (c) includes forming process water from the pH- adjusted effluent stream for use in both the heap leaching of a metal-containing material and the forming of a metal-containing concentrate.

28. The method defined in any one of claims 17 to 22, wherein step (b) includes adjusting the pH of both heap leach and concentrator effluent streams and forming a pH- adjusted heap leach effluent stream and a pH-adjusted concentrate effluent stream, and step (c) includes forming process water from the pH-adjusted heap leach effluent stream and the pH-adjusted concentrator effluent stream for use in at least one of heap leaching of a metal-containing material and the forming of a metal-containing concentrate.

29. The method defined in any one of claims 17 to 22 includes transferring the at least one pH-adjusted effluent stream into a single effluent storage unit.

30. The method defined in any one of claims 17 to 22 includes transferring two pH- adjusted effluent streams into separate effluent storage units, with one effluent stream to one effluent storage unit and another effluent stream to another effluent storage unit.

31. The method defined in any one of claims 17 to 30 includes transferring heat generated from one circuit to the other circuit.

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