Beneficiation of ores and equipment therefor

Abstract

The invention relates to a method and an apparatus for beneficiation of ore. An apparatus, when used for beneficiation of ore, comprises a separation unit separating feed material into a product stream comprising a concentrated product and a leach stream comprising arsenic via a leaching process, an oxidation unit producing an oxidized solution from the leach stream, and a recovery unit recovering a reagent from the oxidized solution for reuse in the leaching process.

Description

Technical Field

[0001] The present invention relates to methods and apparatus for beneficiating ores, and more particularly, but not exclusively, to methods and apparatus for beneficiating sulfide ores to recover minerals such as copper, which have improved cost-effectiveness and / or energy efficiency. Background Technology

[0002] With the depletion of clean ore deposits, the proportion of exploitable dirty ore bodies is increasing, posing a growing challenge to global mining operations. The goal is to process the material within the ore body to recover valuable mineral components. However, ore beneficiation requires separating the mineral components from the surrounding gangue and other impurities, which must then be disposed of or at least managed at the mine or processing site.

[0003] Typically, the release of valuable minerals from surrounding gangue and impurities may involve the leaching of the ore or its concentrate in chemical reagents. For example, conventional leaching methods for treating copper-containing sulfide ores require large quantities of reagents and, at least in part, tend to be expensive and environmentally unfriendly. Furthermore, depending on the reactants used and the nature of the leaching, several downstream processing steps are usually required to ensure adequate recovery of minerals from the leaching wash.

[0004] Copper (Cu) is an important resource used in a variety of applications. With the depletion of clean ore bodies, the proportion of impure ore bodies available for mining is increasing, posing a growing challenge to the global copper mining industry. One of the most significant impurities present in low-quality copper ore bodies is arsenic (As). Arsenic is known to have harmful effects on health and the environment if left untreated.

[0005] Given the environmental and safety concerns arising from the processing of copper deposits with significant arsenic content, many jurisdictions worldwide have established maximum acceptable concentrations of arsenic in mine products. Traditionally, leaching arsenic from copper products to remove it requires the addition of large quantities and expensive caustic reagents and the management of caustic waste streams. Therefore, these conventional leaching methods are generally costly and environmentally unfriendly.

[0006] It is worth noting that copper is commonly found in deposits containing other valuable minerals such as lead (Pb), zinc (Zn), gold (Au), tellurium (Te), and silver (Ag). Recovering these minerals during copper beneficiation processes to improve the commercial yield of mining operations is advantageous. Furthermore, it is beneficial if byproducts from the beneficiation process possess marketable properties and / or grade.

[0007] In this context, there is a need for copper mining methods that offer improved cost-effectiveness and / or energy efficiency, or at least provide a useful alternative for the public. This invention was conceived with these disadvantages in mind. Summary of the Invention

[0008] In a first aspect, the present invention provides an apparatus, when used for beneficiation of ore, comprising: a separation unit that separates a feed into a product stream containing a concentrated product and a leaching stream containing arsenic via a leaching process; an oxidation unit that generates an oxidation solution from the leaching stream; and a reclamation unit that recovers reagents from the oxidation solution for reuse in the leaching process.

[0009] The reagent used in the leaching process may consist of both recycled reagent from the recovery unit and fresh reagent from the supply. This reagent may be sodium hydroxide.

[0010] In some embodiments, the separation unit may include a filter arranged to extract solid product from the leachate stream via a filtration process. The filter may be a filter press equipped with membrane squeezing. The solid product may contain at least one of antimony, copper, lead, gold, nickel, and tellurium.

[0011] The separation unit may include a recirculation loop for recirculating at least a portion of the leach stream. The separation unit may separate the feed into a product stream and a leach stream by washing, and the recirculated portion of the leach stream contains leach washings. The recirculated leach stream may contain sodium sulfide.

[0012] In some embodiments, the oxidation unit may include a pressure vessel arranged to oxidize the leachate stream. Optionally or additionally, the oxidation unit may include a condenser that condenses the vapors generated during the oxidation process, wherein the condensate is transferred to a separation unit for reuse.

[0013] The oxidation unit may include a filter arranged to recover additional products from the leaching stream of the oxidation process. The filter may be a candle filter. The additional products may include at least one of gold, antimony, and tellurium.

[0014] In some implementations, the recovery unit may include a precipitation module that removes arsenic as a precipitate from the oxidation solution. The precipitate may be in the form of a calcium arsenate precursor. Reactants may be added to the oxidation solution in the precipitation module. The reactants may be lime.

[0015] The precipitation module can be arranged to produce glass from the precipitate. Optionally, the precipitation module can be arranged to produce scorodite from the precipitate. Optionally, the precipitation module can be arranged to produce geopolymer from the precipitate.

[0016] In some implementations, the recovery unit may include a crystallization module that releases the reagent by crystallizing impurities. The crystallized impurities may include Glauber's salt. The crystallization module may be arranged to produce sodium sulfate as a byproduct from the crystallized impurities.

[0017] The crystallization module may include a splitter arranged to break down sodium sulfate into sodium hydroxide and sulfuric acid products that can be used as reagents.

[0018] In some implementations, the recovery unit may include an evaporation module arranged to increase the concentration of the reagent via an evaporation process.

[0019] The equipment may further include a preparation unit arranged to feed a feedstock to the separation unit with a predetermined arsenic concentration. The predetermined arsenic concentration may be selected from a range extending between 0.5% w / w and 5.2% w / w. For example, the predetermined arsenic concentration may be one of about 1%, 2%, 3%, 4%, or 5% w / w. The raw ore material supplied to the preparation unit may be of low grade.

[0020] In a second aspect, the present invention provides an ore beneficiation method comprising: separating a feed into a product stream containing a concentrated product and a leaching stream containing arsenic via a leaching process; oxidizing the leaching stream to produce an oxidized solution; and recovering reagents from the oxidized solution for reuse in the leaching process.

[0021] In a third aspect, the present invention provides an apparatus, when used for ore beneficiation, comprising: a separation unit that separates a feed into a concentrate stream containing product solids and a leaching stream containing arsenic via a leaching process; and an oxidation unit that oxidizes the leaching stream and recovers additional products therefrom via a filtration process.

[0022] In a fourth aspect, the present invention provides an ore beneficiation method comprising: separating a feed into a concentrate stream containing product solids and a leaching stream containing arsenic via a leaching process; oxidizing the leaching stream; and recovering additional products from the leaching stream via a filtration process.

[0023] In a fifth aspect, the present invention provides an apparatus for beneficiation of ore, the apparatus comprising: a separation unit that separates a feed into a concentrate stream containing products and a leaching stream containing arsenic via a leaching process; and a recovery unit disposed downstream of the separation unit that recovers reagents from the leaching stream for reuse in the leaching process.

[0024] In a sixth aspect, the present invention provides an ore beneficiation method comprising: separating a feed into a concentrate stream containing a product and a leaching stream containing arsenic via a leaching process; and recovering reagents from the leaching stream for reuse in the leaching process.

[0025] In a seventh aspect, the present invention provides an apparatus, when used for ore beneficiation, comprising a recovery unit arranged to recover caustic alkali reagent from a leaching stream in an upstream leaching process. The recovery unit includes: a precipitation module that produces a filtrate containing the caustic alkali reagent via a reaction between the leaching stream and a lime supply; a crystallization module that removes crystallized impurities from the filtrate; and an evaporation module that evaporates the remaining filtrate, thereby increasing the concentration of the caustic alkali reagent for reuse in the upstream leaching process.

[0026] In an eighth aspect, the present invention provides a method for recovering caustic alkali reagent from a leaching stream of an upstream leaching process for use in ore beneficiation, comprising: precipitating a filtrate containing the caustic alkali reagent via a reaction of the leaching stream and a lime supply; crystallizing and removing impurities from the filtrate; and evaporating the remaining filtrate to increase the concentration of the caustic alkali reagent for reuse in the upstream leaching process. Attached Figure Description

[0027] The invention will now be described by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0028] Figure 1 This is a flowchart illustrating an ore processing apparatus according to an embodiment of the present invention;

[0029] Figure 2 This is an enlarged view of the preparation unit of the ore processing equipment;

[0030] Figure 3 This is an enlarged view of the separation unit of the ore processing equipment;

[0031] Figure 4 This is an enlarged view of the oxidation unit of an ore processing equipment;

[0032] Figure 5 This is an enlarged view of the recycling unit of the ore processing equipment;

[0033] Figure 6 This is an enlarged view of the sedimentation module in the recycling unit;

[0034] Figure 7 This is an enlarged view of the crystallization module of the recycling unit;

[0035] Figure 8 This is an enlarged view of the evaporation module of the recovery unit;

[0036] Figure 9 This is a schematic diagram of a method for beneficiating ore according to an embodiment of the present invention;

[0037] Figure 10 This is a schematic diagram of a method for beneficiating ore according to an embodiment of the present invention;

[0038] Figure 11 This is a schematic diagram of a method for beneficiating ore according to an embodiment of the present invention; and

[0039] Figure 12 This is a schematic diagram of a method for beneficiating ore according to an embodiment of the present invention. Detailed Implementation

[0040] In the following detailed description, reference is made to the accompanying drawings, which form part of the detailed description. It will be readily understood that the aspects of this disclosure, as generally described herein and shown in the accompanying drawings, can be arranged, replaced, combined, separated, and designed in a variety of different configurations, all of which are considered in this disclosure.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. While any methods and materials similar to or equivalent to those described herein may also be used in the practice or testing of this invention, a limited number of exemplary methods and materials are described herein.

[0042] This paper describes a copper ore beneficiation method and equipment for processing low-grade copper into marketable concentrates with improved cost-effectiveness and energy efficiency. Figures 1 to 12 The embodiments of the invention shown are illustrated. It should be understood that the invention is also suitable for the beneficiation and / or recovery of other minerals found in sulfide-based deposits, such as iron (Fe), antimony (Sb), gold (Au), and nickel (Ni).

[0043] refer to Figure 1 The figure shows an apparatus 10 for copper ore beneficiation according to an embodiment of the present invention. The apparatus 10 is shown overall in the figure, while... Figures 2 to 8 Its individual units and modules are shown, wherein the units and modules are integrated together to provide device 10.

[0044] Generally, the equipment 10 includes a preparation unit 12 arranged to receive a supply of ore mined from the ore body. The mined ore is preferably, but not limited to, low-grade copper ore. The preparation unit 12 is arranged to provide an input feed to a separation unit 14. The separation unit 14 is arranged to separate the input stream into a product stream containing valuable copper products and a leaching stream via a leaching process. The leaching stream is then fed into an oxidation unit 16. The oxidation unit 16 is configured to oxidize the leaching stream, recover additional products such as gold and antimony, and supply the remaining filtrate to a recovery unit 18. The recovery unit 18 is configured to produce a calcium arsenate precursor (which provides a means of on-site safe management of arsenic) and recover reagents from the oxidation solution for subsequent reuse in the leaching process.

[0045] Advantageously, it should be understood that the apparatus 10 described herein can be used to achieve arsenic management at the ore mining site. Therefore, toxic materials do not need to be transported to densely populated areas, posing health risks. Storing arsenic at the mining site under environmentally stable conditions further reduces environmental and health risks. Furthermore, copper is commonly found in deposits containing other metals such as lead, zinc, gold, and silver. Apparatus 10 improves the recovery of these other valuable metals during copper beneficiation processes to increase the commercial value of the beneficiation process. In addition, byproducts from the beneficiation process can also be marketable, increasing profits and reducing waste. Moreover, in addition to removing arsenic and realizing the value of gold, antimony, and tellurium, apparatus 10 is configured to allow for the recovery and recycling of reagents and water to minimize costs and enhance process sustainability and environmental management.

[0046] In this specification, the terms “feed concentrate” and / or “raw ore feed” are understood collectively to refer to relatively “low-grade” or “sub-grade” loose rocks and minerals that have been extracted from the ore body (mechanically or by natural processes) – typically sulfide ores with elevated arsenic levels, including, for example, copper ores with arsenic content of about 0.5% w / w or more. Processing such mined ores by conventional means is considered inefficient and unsafe.

[0047] The various units or modules of the apparatus 10 will now be described in detail with reference to the accompanying drawings. The units are described in a sequence that can generally be considered sequential, relating to the entire mineral processing process.

[0048] First refer to Figure 2The preparation unit 12 is discussed. As shown, the preparation unit 12 is arranged to receive a raw feed 20 of low-quality ore and to convey a feed concentrate 22 with a suitable predetermined As content to the separation unit 14. The raw feed 20 may be, for example, a run-of-mine (ROM) feed taken from an ore body with a known As content, and / or a blend of different feeds containing known As contents in a set proportion to produce a feed concentrate 22 with a target As content suitable for subsequent processing. Preferably, the target As content of the feed concentrate 22 is in the range of 0.5% w / w to 5% w / w As. Although in a preferred embodiment, the feed concentrate 22 is provided in the form of a slurry containing approximately 50% w / w solids, it should be understood that the feed concentrate 22 may be any suitable form for subsequent processing, such as a filter cake with a lower moisture content (e.g., 8%-10% moisture), or a slurry with a different solid composition.

[0049] Now go to Figure 3 The diagram shows a separation unit 14. As shown, feed concentrate 22 from preparation unit 12 enters separation unit 14 as input to the leaching process, where feed 22 is separated into a product stream 24 containing concentrated product and a leaching stream 26 containing impurities. An alkaline leaching process uses reagent 28 as input to the separation unit to selectively extract arsenic-containing impurities from the stirred feed concentrate 22. Preferably, reagent 28 is a caustic alkali reagent, such as sodium hydroxide, which generates sodium sulfide in situ during the leaching process. Both sodium hydroxide 28 and the generated sodium sulfide participate in the leaching process. In a preferred embodiment, reagent 28 used in the leaching process is a mixture of recovered sodium hydroxide from recovery unit 18 and fresh sodium hydroxide supplied to separation unit 14 from an external supply.

[0050] The leaching process is preferably operated at a suitable high temperature. For example, the temperature could be approximately 95°C. Depending on the concentration of impurities in the feed concentrate, the exposure to reagent 28 or the leaching residence time can vary, for example, between 4 hours and 30 hours. It should be understood that for impurity concentrations in the leaching concentrate 22 exceeding approximately 3% w / w, a longer leaching residence time may be required. Similarly, for impurity concentrations below approximately 1%, a shorter leaching residence time may be required.

[0051] Separation unit 14 is arranged to extract substantially all impurities from feed concentrate 22. Preferably, greater than about 95% of the arsenic content in feed concentrate 22 is extracted via a leaching process, while the extraction of product materials such as copper, iron, zinc, aluminum, and lead is substantially negligible. In this manner, arsenic and / or other impurities such as antimony (Sb) form a liquid portion, which is then filtered to separate and wash away potentially marketable solid mineral products such as copper, lead, and nickel from the impurities extracted into the liquid portion of feed concentrate slurry 22 during the leaching process.

[0052] Regarding the illustrated embodiment, separation unit 14 uses a filter to separate the leaching slurry into a concentrate product in the form of product stream 24 and leaching stream 26. Preferably, the filter is provided in the form of a filter press with washing and purging capabilities. For example, the filter can be a vertical tower press. However, it should be understood that other types of filters and devices suitable for separating solid products from liquids containing impurities can also be used—for example, a series of decanter centrifuges are also contemplated. The filter press is preferably equipped with membrane extrusion to minimize the risk of impurities being entrained in product stream 24. During the filtration process, product stream 24 is washed to further prevent or at least mitigate contamination of the solid product within product stream 24 by impurities extracted into leaching stream 26. After the filtration process, product stream 24 can be in the form of a filter cake containing solids, which can then be dehydrated (e.g., by purging with compressed air) to minimize water entrainment. In this way, it should be understood that the washed product or clean concentrate 24 may contain about 10% moisture after processing by separation unit 14.

[0053] The aim is to minimize the washing ratio required during the filtration process in separation unit 14, thereby improving the overall efficiency of device 10, and, in particular, reducing the evaporation requirements of recovery unit 18. Therefore, the washing water or leachate used for washing product stream 24 is preferably recycled in loop 30. Figure 3 As shown, leaching recirculation 30 represents a portion of the leaching stream 26 and is recycled as a washing solution to the filtration process of separation unit 14. Preferably, the recirculation portion is a mixture of enriched leaching solution (PLS) and washing liquid. Furthermore, it is preferable to feed a portion of leaching recirculation 30 (containing sodium sulfide) to the leaching process of separation unit 14 to reduce the required sodium hydroxide input level, thereby improving the efficiency and performance of the leaching process. It is also preferable to heat the washing solution, for example, to about 70°C, which has been shown to improve washing efficiency and minimize crystallization of concentrate product 24.

[0054] The product 24 output from separation unit 14 can be further processed, stored, or transported. For example, product 24 can flow by gravity from the filter onto a screw conveyor for storage or transport. The leachate stream 26, containing extracted impurities, can simultaneously enter oxidation unit 16. It should be understood that the outputs of both product 24 and leachate stream 26 can be achieved using any suitable means for separately conveying the solid and liquid separated products without contamination.

[0055] Now go to Figure 4 The diagram shows oxidation unit 16. Oxidation unit 16 is configured to receive leaching stream 26 from separation unit 14. For example, at least a remaining portion of leaching stream 26 (i.e., after being diverted via recirculation 30) can be fed into oxidation unit 16 by gravity flow from filter input to tank, optionally stored, and pumped into oxidation unit 16.

[0056] Oxidation unit 16 includes a pressure vessel or autoclave to which leaching stream 26 is supplied by gravity flow or pumping. For example, the pressure vessel may comprise a conventional four-compartment submarine-type autoclave. It should also be understood that any suitable arrangement of the pressure vessel for oxidizing the impurity stream can be used, and the pressure vessel can be constructed of any suitable material capable of withstanding high pressure. The pressure vessel is arranged to oxidize leaching stream 26 using the supply of reactant 34 to produce an oxidized solution 32. Preferably, the supplied reactant 34 is industrial-grade oxygen, for example, greater than about 99.5% w / w, to prevent the accumulation of inert gases in the pressure vessel, thereby reducing the need for frequent venting of the pressure vessel.

[0057] By applying pressure oxidation to the leach stream 26 in a pressure vessel, substantially all (e.g., about 99%) of the reduced sulfur in the leach stream 26 is oxidized to sodium sulfate, and arsenic in the leach stream 26 is removed from As... 3+ Oxidation to As 5+ The valence state is prepared for downstream precipitation in recovery unit 18. As shown, the pressure vessel is operated at a target temperature preferably selected from the range of about 150°C to 220°C (or more preferably about 170°C) and a pressure of about 1,400 kPa. In a preferred embodiment, the residence time of the leach stream 26 in the pressure vessel of oxidation unit 16 is about 2 hours. It should be understood that the residence time of the solution in the pressure vessel depends on the temperature and pressure of the autoclave and the supplied reactants. The target temperature is obtained by the heat provided by the exothermic oxidation of the reduced sulfur in the leach stream 26 and mitigated by cooling (e.g., cooling the cooling coils in the pressure vessel). It should be understood that the temperature of the pressure vessel can also be controlled by selectively discharging the generated flash steam to the flash vessel.

[0058] The discharge and flash from oxidation unit 16 includes low-pressure steam generated by the oxidation process, which is advantageously condensed by a condenser and preferably transferred to separation unit 14 for reuse. The recirculated steam may be flashed to the atmosphere, or alternatively, may be used in leaching washes to wash the feed concentrate 22.

[0059] After oxidation in a pressure vessel, additional product 36 can be recovered via a filtration process. Specifically, oxidation unit 16 includes a filter to recover additional solid product precipitate 36, which may contain gold, antimony, and tellurium. For example, the oxidized stream can be gravity-fed into a discharge tank and pumped to a candle filter. It should be understood that any suitable filter can be used. Typically, the oxidation solution 32 contains less than about 1% w / w of solid precipitate 36 to be separated and extracted. After filtration, the resulting filter cake containing additional product 36 is washed to minimize the carryover of contaminants such as impurities from the oxidation solution 32. The additional solid product 36 is then transferred, for example, by compressed air discharge, for further processing, storage, transportation, or sale. The additional product 36 is optionally re-slurryed with water. After the additional product 36 is extracted from the oxidation solution 32, the remaining portion of the solution 32 containing impurities is conveyed to recovery unit 18.

[0060] like Figure 5 As shown, the recovery unit 18 is configured to recover reagent 28 from the oxidation solution 32 for reuse during the leaching process. Specifically, sodium hydroxide reagent 28 is extracted from the oxidation solution 32 via a series of processes performed through its respective modules 38, 40, and 42. Modules 38, 40, and 42 are further configured to extract arsenic-containing impurities from the oxidation solution 32, and optionally, to further process the impurities into additional marketable products.

[0061] The following paragraphs now focus on the arrangement of the corresponding modules within the recycling unit 18 of the illustrated embodiment.

[0062] Go to Figure 6 The oxidation solution 32 from oxidation unit 16 is supplied or otherwise introduced into precipitation module 38 via gravity flow, pumping, or other means. As shown, precipitation module 38 includes a pressure vessel or autoclave to which the oxidation solution 32 is pumped or otherwise suitably transferred. Precipitation module 38 is configured to extract arsenic impurities from oxidation solution 32 and further process the arsenic impurities into precursor 44, which can be converted or otherwise encapsulated into arsenic byproduct 46. Optionally, the arsenic extracted by precipitation module 38 can be stored or disposed of.

[0063] The pressure vessel for precipitation module 38 can be provided, for example, in the form of a submarine-type autoclave, in which the solution is transferred between chambers via baffle overflow. It should also be understood that any suitable arrangement of pressure vessel for precipitating a solution containing impurities under caustic alkaline conditions (e.g., vertical autoclave, loop reactor, or pipe reactor) can be used, and the pressure vessel can be constructed of any suitable material.

[0064] The pressure vessel is operated at a suitable high temperature to allow precursor 44 to precipitate from the oxidizing solution 32 under caustic alkaline conditions. Preferably, the precipitate is in the form of calcium arsenate precursor 44. For example, the pressure vessel can be operated at a target temperature of about 170°C and a target pressure of about 700 kPa, the same pressure as the saturated vapor generated by the precipitation module 38. Therefore, overpressure gas is not required. Heating of the pressure vessel can be provided by a belt heater disposed around the pressure vessel. Cooling can be provided by a cooling coil containing cooling water. It should be understood that any suitable heating and cooling arrangement for the precipitation reaction under caustic alkaline conditions in the pressure vessel can be employed. The cooling device of the pressure vessel also serves a shut-off purpose.

[0065] Reactant 48 is added to the pressure vessel of precipitation module 38 at a rate or proportion matching the inflow impurity mass flow rate of oxidizing solution 32. Preferably, reactant 48 is slaked lime, causing a calcium arsenate precipitation reaction. Sodium hydroxide is produced by the reaction and remains in solution after precursor 44 precipitates. As shown, precursor 44 can then be stored, transported, sold, or further processed by an arsenic fixation process to produce arsenic byproduct 46. For example, arsenic-based product 46 can be glass, styrax, and / or geopolymers.

[0066] Preferably, the oxidizing solution 32 is stirred during the reaction. The precipitation module 38 includes a suitable stirring device. For example, in an embodiment, the stirrer may be provided in the form of an axial impeller. It should be understood that any suitable stirring device for a pressure vessel can be used. After precipitation, the precipitated slurry 50 is discharged into a flash vessel, which depressurizes the slurry 50 to atmospheric pressure while increasing the concentration of the solution. The flash vessel can be constructed of any suitable high-strength, crack-resistant, and corrosion-resistant material.

[0067] The steam generated by the reaction is condensed in the condenser of the precipitation module 38, indirectly using cooling water. The condensed steam is preferably transferred to the separation unit 14 for reuse as leaching wash to wash the feed concentrate 22.

[0068] The precipitated slurry 50 is then pumped or otherwise filtered through the discharge tank. Optionally, the discharged precipitated slurry 50 can be transferred to a tank for storage prior to filtration. Filtration of the precipitated slurry 50 extracts the precursor 44 from the precipitated slurry 50. In this way, it should be understood that the precipitation module 38 includes a filter, preferably in the form of a filter press with membrane extrusion, to minimize entrainment of the liquid in the precipitated slurry 50 into the solid calcium arsenate product 44. This helps to mitigate the entrainment of caustic alkali liquid within the precursor 44 and / or byproduct 46, which would result in the loss of caustic alkali reagent 28 and reduce the efficiency of the equipment.

[0069] Following filtration, the precursor 44 (preferably in the form of a filter cake) is washed to further prevent contamination and to further recover any entrained caustic alkali 28. Preferably, a low wash ratio is used to reduce downstream evaporation requirements. The applicant's tests have shown that the process water used for washing the precursor 44 achieves approximately 95% washing efficiency relative to sodium hydroxide. The precursor 44 can also be further reduced in moisture content by squeezing, purging with compressed air, or by other dehydration devices. It has been found that approximately 90% or more of the calcium is extracted from the oxidation solution 32 via the precipitation module 38, and the resulting precipitate slurry 50 contains less than approximately 1 g / L of arsenic impurities.

[0070] Then the remaining portion of the precipitated slurry or filtrate 50 is conveyed to the crystallization module 40, now referencing Figure 7 Let's have a discussion.

[0071] Crystallization module 40 is configured to release reagent 28 from precipitate solution 50 by crystallizing any remaining impurities in precipitate solution 50. Crystallization module 40 includes a crystallizer, preferably a forced circulation type cooled crystallizer with stirring within the crystallizer container. The crystallizer cools the input precipitate solution to essentially 0°C, producing a crystallized slurry 54. At this temperature, the solubility of sodium sulfate in precipitate solution 50 is about 25 g / L, and the solubility of arsenic is about 1 g / L, leading to the crystallization of sodium sulfate (Na₂SO₄·10H₂O)₂ and a small amount of sodium arsenate dodecahydrate (Na₃AsO₄·12H₂O). The crystallization of sodium sulfate 52 has a dehydrating effect on the solution, resulting in an increase in the concentration of sodium hydroxide. For example, the sodium hydroxide concentration can be increased from about 110 g / L to about 150 g / L through the crystallization process.

[0072] Regarding the illustrated embodiment, the crystallizer includes a refrigerant device for temperature control. For example, the refrigerant device could be a water-cooled cooler with forced circulation and an inline heat exchanger. It should be understood that any suitable refrigerant device suitable for cooling the precipitate solution 50 to a target temperature of essentially 0°C can be used. Typically, the crystallizer has a residence time of 8 hours.

[0073] Preferably, the crystallization module 40 may also include an intermittent centrifuge into which the crystallization slurry 54 is periodically pumped from the crystallizer. For example, the centrifuge may be a peeler centrifuge. The centrifuge substantially separates the sodium sulfate crystals from the liquid in the crystallization slurry 54 in batches. For example, the moisture content of the crystals may be approximately 2% after centrifugation, minimizing contamination of the crystals and reducing the loss of caustic soda reagent 28 and soluble arsenic. The filtrate or liquid from the crystallization slurry 54 is then conveyed to the evaporation module 42 for further processing.

[0074] The crystals are washed in a centrifuge to further prevent contamination from the liquid portion of the crystallization slurry 54. Preferably, to avoid redissolving the crystals during washing, the washing solution is saturated sodium sulfate, and the washing is carried out at essentially 0°C. Optionally, the crystal washing solution from the centrifuge can be transferred to a separation unit 14 by a pump or the like for use as a leaching solution. The washed crystals are then discharged from the centrifuge (e.g., via a scraper discharge mechanism) and fed by gravity into a stirred redissolving tank. The redissolving tank combines the crystals with process water to form a solution of known sodium sulfate concentration. This dissolved crystal solution 56 can then be stored, transported, sold, or further processed.

[0075] like Figure 6 As shown, the dissolved crystalline solution 56 can undergo further processing to remove co-crystallized arsenic and other entrained impurities to produce a high-grade anhydrous sodium sulfate product 58. It should be understood that a "high-grade" anhydrous sodium sulfate product refers to sodium sulfate with an arsenic level substantially less than about 10 ppm. This further processing includes precipitating arsenic with quicklime to remove more than about 95% of the entrained arsenic impurities (as sodium arsenate) from the dissolved crystalline solution 56. Next, the crystalline solution 56 is subjected to evaporation crystallization to produce the anhydrous sodium sulfate product 58.

[0076] Preferably, the crystallization module 40 comprises four stirred precipitation removal heated tanks, preferably arranged in series. A dissolved crystal solution 56 is provided to the first of the four tanks by gravity flow, pumping, or other suitable means. A quicklime slurry is added to the first tank to precipitate calcium arsenate. Preferably, the quicklime slurry is added at a molar ratio of about 2:1 to the arsenic in the crystal solution 56. For example, the quicklime slurry can be about 30% ww. Preferably, the reaction is operated at about 95°C, as this reaction temperature has been found to improve kinetics and the degree of precipitation. It should be understood that the reaction can also be operated at any suitable temperature to allow precipitation of calcium arsenate. For example, heating of the tanks can be provided by any suitable heating device, such as a laboratory hot plate.

[0077] Preferably, the pH range of solution 56 during arsenic removal is between about 10 and about 11. The applicant has determined that such a ration is optimal for arsenic removal. While it has been found that solutions generally do not require strict pH control, adding sulfuric acid to a tank can result in pH adjustment. In particular, higher concentrations of arsenic or sodium hydroxide in solution 56 (or arsenic concentrations greater than about 20 ppm) typically require pH control during arsenic removal. In a preferred embodiment, solution 56 resides in the tank for about 4 hours.

[0078] The precipitated crystal solution is then pumped or otherwise supplied through a filter to separate the solids from the filtrate or liquid of the precipitated crystal solution. The filter can be, for example, a candle filter. The filtrate is then transferred to an evaporative crystallizer to produce a high-quality anhydrous sodium sulfate product 58. For example, the evaporative crystallizer can be a forced circulation type. It has been found that evaporative crystallizers remove approximately 65% ​​of the sodium sulfate as anhydrous sodium sulfate crystals from the solution via water evaporation under vacuum. It is contemplated that the crystallizer can be constructed from any suitable corrosion-resistant material with high strength, toughness, and crack resistance. The crystallizer preferably operates at approximately 80°C. For example, the evaporative crystallizer may include heating devices such as heating belts to maintain the target temperature. The slurry in the crystallizer body is periodically pumped from the bottom to an intermittent centrifuge, which separates the anhydrous sodium sulfate crystals from the liquid of the precipitated crystal solution after evaporative crystallization. It has been found that the exit moisture content of the anhydrous sodium sulfate crystals 58 is essentially 2%.

[0079] The sodium sulfate crystals 58 can then be dried to remove any residual moisture. The resulting high-quality anhydrous sodium sulfate powder 58 meets industrial specifications for sale and can be stored, transported, or further processed. Optionally, such as Figure 1As shown, all or part of the sodium sulfate product 58 can be further processed into sodium hydroxide 60 and sulfuric acid 62 through salt decomposition. The resulting sodium hydroxide can be reused as caustic alkali 28 and supplied to separation unit 14. Optionally, the sodium hydroxide and / or sulfuric acid byproducts can be sold.

[0080] Now for reference Figure 8 Evaporation module 42 is described. The filtrate or liquid from the crystallization slurry 54 of crystallization module 40 is supplied to evaporation module 42. For effective reuse as caustic alkali reagent 28 during the leaching process in separation unit 14, the concentration of sodium hydroxide needs to meet a specific concentration threshold. Preferably, the concentration threshold is in the range of about 150 g / L and about 30% w / w. Figure 8 As shown, the filtrate or liquid from the crystallization slurry 54 of the crystallization unit 40 is fed into the evaporation module 42 by gravity flow, pumping or other suitable means to increase the concentration of the reagent through the evaporation process.

[0081] Evaporation module 42 includes an evaporator, preferably a falling film type evaporator with a heat input provided by low-pressure steam. It should be understood that any suitable evaporator or heating device can be used. In a preferred embodiment, sodium sulfate precipitates from the solution during evaporation and is retained along with recycled sodium hydroxide, also as recycling reagent 28 to separation unit 14.

[0082] Although not shown in the figure, it is conceivable that the evaporation module 42 may include a condenser that condenses the vapor generated during the evaporation process, with the condensate transferred to a process water tank for reuse. It should be understood that the recovery and recycling of reagents and water minimizes costs and enhances the sustainability and environmental management of the process provided by device 10.

[0083] Now for reference Figure 9 This document describes an ore beneficiation method 100 that can be performed by the apparatus 10 described herein.

[0084] In separation step 110, the feed is separated into a product stream containing the product and a leaching stream containing arsenic via a leaching process. For example, during this step, feed 22 is received by separation unit 14, where the feed is separated into a product stream 24 containing copper solids and a leaching stream 26 containing arsenic.

[0085] In oxidation step 120, the leachate stream is oxidized to produce an oxidized solution. For example, during this step, the leachate stream 26 from separation unit 14 may be oxidized in a pressure vessel to produce an oxidized solution 32.

[0086] In recovery step 130, reagents from the oxidation solution are recovered for reuse in the leaching process. For example, during this step, oxidation solution 32 is received from oxidation unit 16, and reagent 28 is extracted from the oxidation solution through a series of processes performed by corresponding precipitation, crystallization, and evaporation modules 38, 40, 42.

[0087] Now for reference Figure 10 and Figure 11 Further iron ore beneficiation methods 200 and 300 are described. It should be understood that, in general, methods 200 and 300 can form part of the method 100 described above.

[0088] refer to Figure 10 Method 200 includes a separation step 210, wherein the feed is separated into a concentrate stream containing product solids and a leaching stream containing arsenic via a leaching process. For example, during this step, the feed concentrate 22 is separated into a product concentrate stream 24 containing valuable copper products and a leaching stream 26 via a leaching process carried out through separation unit 14, wherein the leaching stream 26 contains impurities such as arsenic.

[0089] In oxidation step 220, the leaching stream is oxidized. For example, during this step, leaching stream 26 containing arsenic impurities is supplied to oxidation unit 16 through separation unit 14 and oxidized under pressure to produce oxidation solution 32.

[0090] In recovery step 220, additional products are recovered from the leachate stream via a filtration process. For example, during this step, the oxidation solution 32 produced by oxidation unit 16 is filtered to separate additional solid precipitates 36, such as gold, antimony, and tellurium, from the remaining liquid portion of the leachate stream 26.

[0091] refer to Figure 11 Method 300 includes a separation step 310, wherein the feed is separated into a concentrate stream containing product and a leaching stream containing arsenic via a leaching process. For example, during this step, feed 22 is received by separation unit 14, wherein the feed is separated into a product stream 24 containing copper solids and a leaching stream 26 containing arsenic by a leaching process performed by separation unit 14.

[0092] In the subsequent recovery step 320, the reagent from the leaching stream is recovered for reuse in the leaching process. For example, during this step, caustic alkali reagent 28 is extracted from the leaching stream 26 through a series of processes carried out by the respective precipitation, crystallization, and evaporation modules 38, 40, 42.

[0093] Now for reference Figure 12 A method for recovering caustic alkali reagent from the leaching stream of an upstream leaching process 400, which can be accomplished by the apparatus 10 described herein, is described.

[0094] In precipitation step 410, the filtrate containing the caustic alkali reagent is precipitated via a leaching stream and a lime supply. For example, during this step, the oxidizing solution 32 is received by the precipitation module 38 of the recovery unit 18 and exposed to lime reactant 48 to produce a precipitate precursor 44, wherein the filtrate from the reaction (in the form of precipitate solution 50) contains the caustic alkali reagent in the form of sodium hydroxide 28.

[0095] In crystallization step 420, impurities are crystallized and removed from the filtrate. For example, during this step, filtrate 50 from precipitation module 38 is received into crystallization module 40 and cooled to produce crystallized slurry 54, which is then filtered to extract the crystallized impurities.

[0096] In evaporation step 430, the remaining filtrate is evaporated, thereby increasing the concentration of the caustic alkali reagent for reuse in the upstream leaching process. For example, during this step, filtrate or liquid from the crystallization slurry 54 from the crystallization unit 40 is fed into the evaporation module 42 and evaporated to increase the concentration of sodium hydroxide reagent 28, which can be reused in the upstream leaching process.

[0097] In summary, embodiments of the present invention provide cost-effective and / or energy-efficient beneficiation methods for low-quality copper ore materials. More specifically, the present invention provides on-site separation and fixation of impurities (e.g., arsenic and antimony) at the ore mining site without the need for expensive downstream metal recovery loops, thereby eliminating the need for long-distance transport of hazardous materials and the associated risks and penalties. Furthermore, some embodiments of the present invention provide multiple recovery, reuse, and recycling loops for optimizing the recovery of leaching reagents from the impurity separation process while minimizing energy use and losses of water and media, thereby minimizing the operating costs of the equipment. Additionally, byproducts from the beneficiation process can also be marketable, increasing profits and reducing waste. The modularity of the described equipment for the beneficiation process allows for scaling up of the equipment according to processing needs, while also utilizing existing and potentially idle plant equipment previously used for more conventional beneficiation processes.

[0098] References to any prior publications (or information derived therefrom) or to any known matter in this specification are not and should not be construed as an acknowledgment or admission, or any form of implication, that such prior publications (or information derived therefrom) or known matter form part of the common general knowledge in the field to which this specification pertains.

[0099] Throughout this specification and the appended claims, unless the context otherwise requires, the word “comprise” and variations such as “comprises” and “comprising” are to be understood as implying inclusion of the said integer or step or group of integers or steps, but not excluding any other integer or step or group of integers or steps.

[0100] legend

[0101]

[0102] Example

[0103] Demonstration Plant

[0104] A. Overview

[0105] To develop and validate the methods and apparatus described herein, a demonstration plant designed for processing 1% w / w and 3% w / w As feed concentrates was utilized.

[0106] The demonstration plant is designed to process 15 kg dry weight equivalent feed concentrate per hour.

[0107] For each As concentration, the preliminary design assumes the following mineralogical characteristics for the feed concentrate: as shown in Table 1.

[0108]

[0109] B. Equipment

[0110] The demonstration plant includes the following units and modules:

[0111] 1. Preparation Unit

[0112] 1.1. Leaching Feed Preparation Area

[0113] 1.2. Reagent Preparation Area

[0114] 2. Separation unit

[0115] 2.1. Leaching area

[0116] 2.2. Leached Product Separation Zone

[0117] 3. Oxidation unit

[0118] 3.1. Pressure Oxidation Zone

[0119] 3.2. Pressure Oxidation Product Separation Zone

[0120] 4. Precipitation module

[0121] 4.1. Calcium arsenate precipitation area

[0122] 4.2. Separation area for calcium arsenate products

[0123] 5. Crystallization module

[0124] 5.1. Glauber's salt crystallization area

[0125] 5.2. Impurity Removal Area

[0126] 5.3. Sodium sulfate crystallization region

[0127] 5.4. Dry Area

[0128] 6. Evaporation module

[0129] 6.1. Caustic alkali evaporation zone

[0130] Factory utilities include:

[0131] Industrial-grade compressed oxygen with a purity of >99.5% is typically supplied in 16-cylinder packs and stored on-site.

[0132] Industrial-grade nitrogen with a purity of >99.5% is typically supplied in 16-cylinder sets and stored on-site.

[0133] • Compressed air generated by an air compressor unit is used for both factory and instrument ventilation.

[0134] C. Operations and Procedures

[0135] The following sections describe in detail the operation of each unit and module in the demonstration plant.

[0136] 1.0 Preparation Unit

[0137] 1.1 Leaching Feed Preparation Area

[0138] The feed concentrate is fed as a filter cake containing 8%-10% moisture into the demonstration plant loop. The feed rate of the concentrate into the leaching loop of the demonstration plant is nominally 15 kg dry solids per hour, or 360 kg per day. The feed concentrate is conveyed from the feed hopper to the feed repulp tank.

[0139] The feed reslurry tank operates continuously and receives feed concentrate filter cake and recycled leach slurry. The feed reslurry tank utilizes high agitation intensity to reslurry the filter cake before it proceeds to the feed recirculation tank. Recycled leach slurry is added to the tank to maintain the desired solids percentage in the feed system.

[0140] The feed recirculation tank is continuously filled by the following flow:

[0141] • Feed concentrate solids from the repulping tank

[0142] • PLS filters that are recycled from the product filter in zone 2.2

[0143] • Leachate from the product filter in area 2.2, and

[0144] • Configure the addition of process water for startup purposes.

[0145] 1.2 Reagent Preparation

[0146] The plant reagents include sodium hydroxide, quicklime, and sodium sulfide. A commercial-grade 50% w / w sodium hydroxide solution is delivered via IBC. For process control and metallurgical accounting purposes, the tank is mounted on a load sensor.

[0147] Commercial-grade 95% w / w quicklime was used in the factory. The quicklime slurry was prepared in 25kg quicklime bags and added to the process through a circular pipe.

[0148] Sodium sulfide is typically prepared for start-up and commissioning tasks by adding the required amount in 25kg packages to the process water in the sodium sulfide reagent tank.

[0149] 2.0 Separation Unit

[0150] 2.1 Leaching area

[0151] Leaching selectively extracts arsenic and antimony from the concentrate using sodium hydroxide and sodium sulfide produced in situ by leaching.

[0152] The leaching train consists of five agitated, covered tanks connected in series. The slurry travels downwards along the leaching train by gravity.

[0153] Regenerated and fresh sodium hydroxide are also pumped from the evaporator in Zone 6.1 to the first leaching tank to ensure that the target caustic alkali concentration (tenor) in the leaching solution is achieved. The slurry is leached at 95°C and atmospheric pressure.

[0154] Leaching produces a leachate with typically >95% arsenic extraction. Extraction of copper, iron, zinc, aluminum, and lead is negligible.

[0155] The leachate is then transferred to the filter feed tank in zone 2.2 via gravity overflow.

[0156] 2.2 Solid-liquid separation of leaching products

[0157] The leaching product solid-liquid separation loop is designed to separate and wash the product concentrate from the leachate, which then undergoes further processing steps. This is achieved using a filter press with washing and purging capabilities.

[0158] The leaching filter is a filter press equipped with membrane extrusion. The filtration design aims to minimize entrainment of the leached PLS into the product filter cake, avoiding arsenic contamination of the product concentrate. With countercurrent washing capability, process water can be used as a second washing solution to further reduce the arsenic concentration in the concentrate. Finally, the filter press has an air purging capability, utilizing compressed air to minimize water entrainment in the product filter cake.

[0159] The filter is equipped with a two-stage washing process. The combined solution in the wash feed tank is pumped to the leaching filter as the first wash (“Wash 1”) in the filtration cycle. The second wash (“Wash 2”), which uses only process water, is transferred from the filter to the wash feed tank, which is typical for countercurrent washing schemes.

[0160] The washing product (clean concentrate) containing ~12% moisture was transferred to a 44-gallon tank at the boundary of the demonstration plant.

[0161] The filtered leached PLS flows by gravity from the product filter to the leached PLS tank (which is stored here before being pumped to the following unit operations):

[0162] • Advance to the autoclave feed tank in the oxidation unit, and

[0163] • Recycled to the feed recirculation tank in Zone 1.2 to provide feed sulfide units to improve leaching performance.

[0164] The wash solution 1 exiting the product filter flows by gravity to the leaching wash outtank (which is stored here before being pumped to the following unit operations):

[0165] • Proceed to the autoclave feed tank in zone 3.1 for oxidation, and

[0166] • Recycle to the feed recirculation tank in zone 1.2 to control the percentage of solids in the leachate.

[0167] The washing solution 2 exiting the product filter flows by gravity into the leaching washing solution in the tank. The reuse of the washing solution minimizes the need for water input into the process and for hot evaporation water.

[0168] 3.0 Oxidation Unit

[0169] 3.1 Pressure Oxidation

[0170] The POX feed tank mixes the incoming leaching PLS and leaching wash solution. The oxidation feed tank is agitated. If interstage flash evaporation is used, the oxidation feed tank also receives flash discharge from the interstage flash vessel.

[0171] The high-pressure oxidation autoclave oxidizes the leach liquor and washing solution into:

[0172] • Oxidizes >99% of reduced sulfur substances into sodium sulfate.

[0173] • Precipitate >99% of soluble gold from the solution.

[0174] • Removing arsenic from As 3+ Oxidation to As 5+ Valence state, which contributes to precipitation in region 4.1, and

[0175] • Precipitate >99% antimony from solution.

[0176] The autoclave is fed by a suitable high-pressure pump, which pumps the feed solution from the autoclave feed tank to the autoclave chamber.

[0177] The autoclave includes a vertical batch autoclave or a conventional four-compartment submarine-type autoclave, in which the solution is transferred between compartments via gravity overflow. The temperature in the first compartment is also capable of being controlled via an interstage flash vessel, in which the solution is released from compartment 1 into the interstage flash vessel.

[0178] Industrial-grade oxygen (>99.5% w / w) is supplied from the compressed oxygen cylinder group to the autoclave.

[0179] Heating of the autoclave is provided by the exothermic oxidation of the reducing sulfur, with a belt heater installed for start-up. Temperature control is provided via cooling coils, flash recirculation, or a combination thereof.

[0180] After the autoclave, the oxidizing solution is discharged into a POX discharge flash vessel. A single flash vessel depressurizes the solution to atmospheric pressure while simultaneously increasing the concentration of substances in the solution.

[0181] 3.2 Solid-liquid separation of pressure oxidation products

[0182] Prior to arsenic removal in Zone 4.1, precipitates (primarily gold and antimony) are recovered from the oxidation solution using a filter.

[0183] The oxidized solution from the flash vessel is transferred to the POX flash discharge tank and stirred before being pumped to the filter.

[0184] A single candle filter removes <1% w / w solids from the oxidation solution. Following filtration, the precipitated filter cake is washed with process water to minimize contaminant carryover into the sodium antimonate pyroantimonate / gold product. The product filter cake is discharged via compressed air, re-slurryed with water within the filter body, and manually transferred to drums at the demonstration plant boundary.

[0185] 4.0 Sedimentation Module

[0186] 4.1 Calcium arsenate precipitation

[0187] The calcium arsenate precipitation autoclave operates at elevated temperatures to precipitate calcium arsenate from the oxidized feed solution. Quicklime is added to the feed tank at a set ratio to the incoming arsenic mass flow rate. Sodium hydroxide is regenerated by the calcium arsenate precipitation reaction, thereby reducing the total caustic alkali input in the loop. Under the process conditions, greater than 90% As is precipitated from the solution.

[0188] The mixing feed tank receives and combines the filtered oxidizing solution from zone 3.2 and the quicklime reagent slurry from zone 1.3.

[0189] The autoclave is fed by a suitable high-pressure slurry pump, which pumps a solution with ~2% w / w solids from the calcium arsenate precipitator feed tank into the autoclave chamber.

[0190] The autoclave is a vertical batch autoclave or a conventional four-compartment submarine-type autoclave, in which the solution is transferred between chambers via overflow through baffles.

[0191] The autoclave is heated by an electric belt heater. The autoclave is stirred by an axial impeller. Cooling coils are installed to provide cooling water for shut-off purposes.

[0192] After the autoclave, the precipitated slurry is transferred to an autoclave discharge flash vessel. A single flash vessel depressurizes the solution to atmospheric pressure, simultaneously increasing the concentration of substances in the solution.

[0193] The discharge holding tank receives the flash discharge slurry and agitates it before pumping it to the filter feed tank.

[0194] 4.2 Solid-liquid separation of calcium arsenate products

[0195] The calcium arsenate filter feed tank is before the material is pumped to the horizontal filter press.

[0196] The filter press is equipped with membrane extrusion. Process water is used to wash the filter cake to achieve a washing efficiency of 95% relative to sodium hydroxide. Compressed air is used to minimize the moisture content of the calcium arsenate precipitate filter cake.

[0197] The washing efficiency of the filtration step can be improved by using a two-stage filtration process, as described below.

[0198] i. The calcium arsenate precipitate containing 30-40% w / w water flows by gravity from the filter to a biaxial screw feeder, which transfers the filter cake to a calcium arsenate reslurry tank. The reslurry tank reslurries the filter cake to 30% w / w solids using process water. The reslurry is then pumped back to the calcium arsenate filter for refiltration, which further removes soluble sodium salts from the calcium arsenate filter cake.

[0199] ii. The re-pulping washed calcium arsenate precipitate drips from the filter onto a biaxial screw feeder, which transfers the calcium arsenate into 44-gallon tanks for storage prior to arsenic fixation.

[0200] The filtrate and washings from the calcium arsenate filter are discharged into the feed tank of the Glauber's salt (GS) crystallizer.

[0201] 5.0 Crystallization Module

[0202] 5.1 Glauber's salt crystallization

[0203] Sulfur is removed from the circuit as sodium sulfate via crystallization. High-grade anhydrous sodium sulfate product is produced in the crystallization module.

[0204] The Glauber's salt (“GS”) crystallizer is a baffle-type cooling crystallizer with stirring inside the crystallizer vessel. This results in the crystallization of Glauber's salt (Na₂SO₄·10H₂O) and a small amount of sodium arsenate dodecahydrate (Na₃AsO₄·12H₂O). The temperature of the crystallizer is controlled by refrigerant supplied from a dedicated water-cooled cooler with an inline heat exchanger. The product crystal slurry is periodically pumped from the bottom of the crystallizer to an intermittent centrifuge.

[0205] GS crystals are separated from the liquid in batches using a scraper-discharge centrifuge. Minimizing outlet moisture is necessary to minimize the amount of reagents and soluble arsenic accompanying the crystals.

[0206] The primary centrifuge fluid from the GS centrifuge flows by gravity into the stirred GS centrifuge tank. The tank is heated by a belt heater to minimize the heat load on the downstream evaporator. The centrifuge fluid is then pumped to the sodium hydroxide evaporator in zone 6.1.

[0207] The washed GS crystals from the centrifuge are discharged via a scraper discharge mechanism and gravity into a receiving tank (GS redissolution tank). The tank is agitated and the GS crystals and process water are combined to dissolve the crystals in solution before further processing in Zone 5.2, or they can be dissolved directly into Zone 5.2 during operation.

[0208] 5.2 Impurity Removal

[0209] The dissolved GS crystals undergo further processing to remove co-crystallized arsenic and other entrained impurities. To produce a high-grade anhydrous sodium sulfate product, the GS crystals undergo a two-stage purification process:

[0210] i. Use quicklime to precipitate arsenic to remove >95% of the contained arsenic (as calcium arsenate).

[0211] ii. Evaporation and crystallization of sodium sulfate solution after impurity removal to produce anhydrous sodium sulfate, wherein any entrained arsenic enters the solution phase.

[0212] Zones 5.2, 5.3, and 5.4 operate together in a campaign mode, separate from the overall demonstration plant. During campaign mode, GS redissolution tanks in Zone 5.1 and dissolved crystal solutions from IBC storage are pumped to the impurity removal precipitation series.

[0213] The impurity removal precipitation series comprises four stirred and heated tanks connected in series. A slurry of quicklime is added at 30% w / w to the first tank to precipitate calcium arsenate. The reaction is temperature-dependent, and the tanks are operated at 95°C to improve kinetics and the extent of the reaction. Satisfactory arsenic removal requires a pH range of 10–11. Under these conditions, the effluent arsenic concentration is <20 ppm.

[0214] Following the calcium arsenate precipitation loop, the slurry is filtered through a candle filter to remove calcium arsenate solids. The filtrate is transferred to the evaporator crystallizer feed tank in Zone 5.3. The calcium arsenate solids are discharged into a 44-gallon drum for storage before arsenic fixation or waste disposal at the demonstration plant boundary.

[0215] 5.3 Sodium sulfate crystals

[0216] The sodium sulfate crystallizer feed tank is stirred and heated by a heating belt.

[0217] The sodium sulfate evaporator crystallizer removes approximately 65% ​​of the sodium sulfate from the solution under vacuum (as anhydrous sodium sulfate crystals). Centrifuged liquid from the downstream centrifuge is recirculated to the feed tank to maintain the discharge of crystal slurry from the crystallizer. Temperature control of the crystallizer is provided by steam from the plant boiler in Zone 7.3 via a forced circulation loop with an inline heat exchanger. The feed solution is introduced into the crystallizer via the forced circulation loop before the inline heat exchanger. The product crystal slurry is periodically pumped from the bottom of the crystallizer to an intermittent centrifuge. The crystallizer utilizes a condenser to condense the evaporate using cooling water from Zone 7.2.

[0218] Anhydrous sodium sulfate crystals are separated from the liquid using a centrifuge. The crystals are then discharged by gravity into a sodium sulfate dryer in zone 5.4.

[0219] The sodium sulfate centrifuge liquid is discharged by gravity into a sodium sulfate centrifuge liquid holding tank, where it is recirculated to the sodium sulfate crystallizer feed tank. Excess centrifuge liquid is discharged into the GS crystallizer feed tank in zone 4.2.

[0220] 5.4 Drying sodium sulfate

[0221] The sodium sulfate dryer removes any residual moisture and produces dry, anhydrous sodium sulfate powder that meets industrial specifications for sale. This sodium sulfate product is then discharged into 44-gallon drums within the boundary of the demonstration plant.

[0222] 6.0 Evaporation Module

[0223] 6.1 Evaporation of caustic alkali

[0224] The caustic alkali evaporator increases the sodium hydroxide concentration before it can be recycled during leaching. The evaporator is a forced-circulation type with low-pressure steam generated by a boiler to provide the heat input. The caustic alkali evaporator utilizes a condenser with 15°C cooling water to condense the evaporated material.

[0225] The evaporated caustic soda solution is transferred to a caustic soda storage tank. The tank is equipped with an electric heating belt.

[0226] The condensate from the caustic alkali evaporator flows by gravity into the evaporator condensate tank.

Claims

1. An apparatus, when used for ore beneficiation, said apparatus comprising: A separation unit that separates the feed into a product stream containing a concentrated product and a leaching stream containing arsenic via a leaching process; and Oxidation unit, which generates an oxidation solution from the leaching stream; and / or A recovery unit that recovers reagents from the oxidation solution for reuse in the leaching process.

2. The apparatus of claim 1, wherein the reagent used in the leaching process comprises both a recovered reagent from the recovery unit and a fresh reagent supplied, and preferably wherein the reagent is sodium hydroxide.

3. The apparatus according to any one of the preceding claims, wherein the separation unit comprises a filter, preferably a filter press equipped with membrane extrusion, the filter being arranged to extract a solid product from the leachate stream via a filtration process, preferably the solid product comprising at least one of antimony, copper, gold, lead, nickel and tellurium.

4. The apparatus according to any one of the preceding claims, wherein the separation unit includes a recirculation loop for recirculating at least a portion of the leachate stream, and preferably wherein the recirculated portion of the leachate stream comprises a leachate washing solution, preferably the leachate washing solution comprises sodium sulfide.

5. The apparatus according to any one of the preceding claims, wherein the oxidation unit comprises a pressure vessel arranged to oxidize the leachate stream, and / or a condenser for condensing the vapors generated during the oxidation process, wherein the condensate is transferred to the separation unit for reuse.

6. The apparatus according to any one of the preceding claims, wherein the oxidation unit comprises a filter, preferably a candle filter, the filter being arranged to recover additional products from the leaching stream of the oxidation via a filtration process, the additional products being preferably at least one of gold, antimony, and tellurium.

7. The apparatus according to any one of the preceding claims, wherein the recovery unit comprises a precipitation module that removes arsenic as a precipitate from the oxidation solution, and preferably wherein the precipitate is in the form of a calcium arsenate precursor.

8. The apparatus according to claim 7, wherein the reactant is preferably lime added to the oxidation solution in the precipitation module.

9. The apparatus of claim 7 or claim 8, wherein the precipitation module is arranged to produce glass and / or onionite and / or geological polymers from the precipitate.

10. The apparatus according to any one of the preceding claims, wherein the recovery unit comprises a crystallization module for releasing the reagent by crystallizing impurities, and preferably wherein the crystallized impurities comprise sodium sulfate.

11. The apparatus of claim 10, wherein the crystallization module is arranged to produce sodium sulfate byproduct from the impurities of the crystallization, and / or the crystallization module includes a decomposer arranged to decompose the sodium sulfate into sodium hydroxide and sulfuric acid products for use as reagents.

12. The apparatus according to any one of the preceding claims, wherein the recovery unit comprises an evaporation module arranged to increase the concentration of the reagent via an evaporation process.

13. The apparatus according to any one of the preceding claims, further comprising a preparation unit arranged to receive raw ore material, preferably low-grade raw ore material, and to supply the feed to the separation unit with a predetermined arsenic content, preferably at a concentration between 0.5% and 5.2%.

14. A method for beneficiating ore, comprising: The feed is separated into a product stream containing concentrated products and a leaching stream containing arsenic through a leaching process; and The leaching stream is oxidized to produce an oxidized solution; and / or The reagent is recovered from the oxidation solution for reuse in the leaching process.

15. An apparatus, when used for ore beneficiation, comprising a recovery unit arranged to recover a caustic alkali reagent from a leaching stream of an upstream leaching process, the recovery unit comprising: A precipitation module that produces a filtrate containing the caustic alkali reagent via a reaction between the leaching stream and the lime supply; A crystallization module that removes crystallized impurities from the filtrate; and An evaporation module evaporates the remaining filtrate, thereby increasing the concentration of the caustic alkali reagent for reuse in the upstream leaching process.

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