Method for removing arsenic from high-arsenic copper ore through segmented intensified leaching

Abstract

The invention discloses a segmented intensified leaching arsenic removal method for high-arsenic copper ore, and belongs to the technical field of mineral processing engineering. The method comprises the following steps: mixing crushed high-arsenic copper ore with additives, namely limestone and sodium hydroxide, and carrying out activation pretreatment through microwave cracking and quenching; a mixed solution of sodium sulfide and sodium hydroxide is adopted as a leaching agent for the pretreated mineral aggregate, and a first-stage ore grinding-leaching process, a second-stage ore grinding process, a synergistic enhanced oxidation process and a second-stage ore grinding-leaching process are sequentially carried out; and the first-stage leachate is returned to the first-stage ore grinding, the second-stage leachate is returned to the second-stage ore grinding, and finally the arsenic-removed high-copper slag is obtained. According to the method, the arsenic mineral structure is effectively destroyed through microwave pretreatment, efficient and selective removal of arsenic and cyclic utilization of the leaching agent are achieved in combination with the segmented enhanced leaching process, and the method has the advantages of being short in process, small in pollution and high in recovery rate.

Description

Technical Field

[0001] This invention relates to the field of mineral processing engineering technology, specifically to a method for staged enhanced leaching to remove arsenic from high-arsenic copper ore. Background Technology

[0002] The core bottleneck in the development and utilization of high-arsenic copper sulfide ores lies in the difficulty of separating copper and arsenic. Typical high-arsenic copper sulfide minerals in these resources mainly include arsenopyrite (Cu). 12 As4S 13 Or Cu3AsS3) and arsenic copper sulfide (Cu3AsS4), the most prominent feature of these two minerals is their high As content. Arsenic copper sulfide and arsenic copper sulfide contain about 19% to 20% As, and the As is present in the molecular structure, making it impossible to separate copper and As from As using physical beneficiation methods such as gravity separation, flotation, and magnetic separation. This results in the copper concentrate having a seriously excessive As content, failing to meet the industry standard of <0.5% As content in copper concentrate entering the plant. As a result, a large amount of high-arsenic copper ore resources cannot be industrially utilized, causing serious resource accumulation and waste.

[0003] Currently, when using sodium sulfide and sodium hydroxide as reagents for alkaline leaching of high-arsenic copper sulfide ores, the arsenic removal effect is often poor. The main reasons are as follows: First, arsenic atoms are densely encapsulated by sulfides, making it difficult for the alkaline solution to directly contact the internal arsenic atoms and react. Second, direct alkaline leaching causes passivation of the mineral surface, forming a dense and insoluble passivation film (such as CuS, Cu2S). Third, arsenic in minerals usually exists in the form of As(III) (such as AsS3). 3- As(III) thioarsenates have relatively poor stability in alkaline solutions and slow reaction kinetics during direct alkaline leaching.

[0004] Therefore, developing a new technology that can efficiently and economically separate arsenic and copper and stably produce low-arsenic copper concentrate or qualified copper products is of great practical significance for the efficient utilization of high-arsenic copper ore resources, alleviating environmental pressure and meeting industrial needs. Summary of the Invention

[0005] To address the problem that conventional alkaline leaching methods for arsenic removal in high-arsenic copper sulfide ores are inefficient and difficult to separate copper and arsenic due to their dense mineral structure, easily passivated surfaces, and slow arsenic reaction kinetics, thus hindering industrial application, this invention provides a staged enhanced leaching method for arsenic removal from high-arsenic copper ores, specifically including the following steps: (1) The high-arsenic copper ore is crushed and screened to obtain high-arsenic copper ore powder.

[0006] (2) Add additives to the high-arsenic copper ore powder obtained in step (1) and mix evenly. Then, pretreat with microwave and quench to obtain pretreated high-arsenic copper ore.

[0007] (3) Mix the high-arsenic copper ore pretreated in step (2) with the leaching agent to obtain a first-stage slurry A. Then grind the first-stage slurry A to obtain a first-stage grinding and leaching slurry.

[0008] (4) Add leaching agent to the first section of leaching slurry obtained in step (3) and mix evenly to obtain a first section of slurry B. Then, stir and leach the first section of slurry B to obtain a stirred leaching slurry.

[0009] (5) The leaching slurry obtained in step (4) is concentrated and dehydrated to obtain an alkaline leaching solution and a leaching residue. The alkaline leaching solution is returned to step (3).

[0010] (6) Add leaching agent to the first leaching residue obtained in step (5) and mix evenly to obtain second slurry A. Then grind the second slurry A to obtain second grinding and leaching slurry.

[0011] (7) Add the mixed agent to the two-stage grinding and leaching slurry obtained in step (6) and mix evenly to obtain a mixed slurry. Then, perform enhanced oxidation on the mixed slurry to obtain an oxidized slurry.

[0012] (8) Add leaching agent to the oxidized slurry obtained in step (7) and mix evenly to obtain two-stage slurry B. Then, perform two-stage stirring leaching on the two-stage slurry B to obtain two-stage stirring leached slurry.

[0013] (9) The two-stage stirred leaching slurry obtained in step (8) is filtered to obtain a two-stage alkaline leaching solution and a two-stage leaching residue. The two-stage alkaline leaching solution is returned to step (6). The two-stage leaching residue is washed and separated to obtain a filter cake. The filter cake is a high-copper slag after arsenic removal.

[0014] Preferably, the high-arsenic copper ore in step (1) of the present invention is arsenopyrite or arsenopyrite.

[0015] Preferably, the particle size of the high-arsenic copper ore powder in step (1) of the present invention is -1 mm.

[0016] Preferably, the additives in step (2) of the present invention are limestone and sodium hydroxide, wherein the amount of limestone added is 1.0%-1.5% of the mass of the high-arsenic copper ore powder, and the amount of sodium hydroxide added is 0.5%-1.0% of the mass of the high-arsenic copper ore powder.

[0017] Preferably, the microwave pretreatment conditions in step (2) of the present invention are: power 500-600W, treatment time 3-5min, and temperature 300-350℃.

[0018] Preferably, the quenching in step (2) of the present invention specifically involves: rapidly cooling the microwave-pretreated high-arsenic copper ore in water at 20-25°C.

[0019] Preferably, in step (3) of the present invention, the leaching agent is composed of a mixture of sodium sulfide aqueous solution and sodium hydroxide aqueous solution, wherein the concentration of sodium sulfide aqueous solution is 2.0 mol / L and the concentration of sodium hydroxide aqueous solution is 1.0 mol / L.

[0020] Preferably, in step (3) of the present invention, the concentration of sodium sulfide in slurry A is 1.0-1.5 mol / L and the concentration of sodium hydroxide is 0.2-0.5 mol / L.

[0021] Preferably, the slurry concentration of the first slurry A in step (3) of the present invention is 60-65 wt%.

[0022] Preferably, the grinding in step (3) of the present invention specifically involves grinding to -0.074mm, which accounts for 70-75wt%.

[0023] Preferably, in step (4) of the present invention, the leaching agent is composed of a mixture of sodium sulfide aqueous solution and sodium hydroxide aqueous solution, wherein the concentration of sodium sulfide aqueous solution is 2.0 mol / L and the concentration of sodium hydroxide aqueous solution is 1.0 mol / L.

[0024] Preferably, in step (4) of the present invention, the concentration of sodium sulfide in slurry B is 0.5-1.0 mol / L and the concentration of sodium hydroxide is 0.1-0.3 mol / L.

[0025] Preferably, the slurry concentration of the first slurry B in step (4) of the present invention is 20-25 wt%.

[0026] Preferably, the conditions for the first stage of stirring leaching in step (4) of the present invention are: stirring and leaching at 50-60°C for 2-3 hours.

[0027] Preferably, the conditions for concentration and dehydration in step (5) of the present invention are: concentration and dehydration until the underflow slurry concentration is 60-65 wt%.

[0028] Preferably, in step (6) of the present invention, the leaching agent is composed of a mixture of sodium sulfide aqueous solution and sodium hydroxide aqueous solution, wherein the concentration of sodium sulfide aqueous solution is 2.0 mol / L and the concentration of sodium hydroxide aqueous solution is 1.0 mol / L.

[0029] Preferably, in step (6) of the present invention, the concentration of sodium sulfide in the second stage slurry A is 1.0-1.5 mol / L and the concentration of sodium hydroxide is 0.5-0.8 mol / L.

[0030] Preferably, the slurry concentration of the second-stage slurry A in step (6) of the present invention is 60-65 wt%.

[0031] Preferably, the grinding in step (6) of the present invention specifically involves grinding to -0.074mm, which accounts for 90-95wt%.

[0032] Preferably, the mixed agent in step (7) of the present invention is composed of a mixture of hydrogen peroxide aqueous solution and sodium chloride aqueous solution, wherein the concentration of hydrogen peroxide aqueous solution is 9.8 mol / L and the concentration of sodium chloride aqueous solution is 1.0 mol / L.

[0033] Preferably, the concentration of hydrogen peroxide in the mixed slurry in step (7) of the present invention is 0.5-1.0 mol / L, and the concentration of sodium chloride is 0.3-0.34 mol / L.

[0034] Preferably, the oxidized slurry concentration in step (7) of the present invention is 10-15 wt%.

[0035] Preferably, the conditions for enhanced oxidation in step (7) of the present invention are: oxidation at 20-25°C for 1.5-2 hours.

[0036] Preferably, in step (8) of the present invention, the leaching agent is composed of a mixture of sodium sulfide aqueous solution and sodium hydroxide aqueous solution, wherein the concentration of sodium sulfide aqueous solution is 2.0 mol / L and the concentration of sodium hydroxide aqueous solution is 1.0 mol / L.

[0037] Preferably, in step (8) of the present invention, the concentration of sodium sulfide in the second stage slurry B is 0.5-1.0 mol / L and the concentration of sodium hydroxide is 0.1-0.3 mol / L.

[0038] Preferably, the slurry concentration of the second-stage slurry B in step (8) of the present invention is 10-15 wt%.

[0039] Preferably, the conditions for the two-stage stirring leaching in step (8) of the present invention are: stirring and leaching at 50-60°C for 2-3 hours.

[0040] Preferably, the washing conditions in step (9) of the present invention are: washing with water until the pH of the washing solution is 6-7.

[0041] Mechanism of the invention: This invention achieves efficient leaching and arsenic removal from high-arsenic copper ores through the synergistic effect of physical pretreatment, chemical leaching processes, and segmented leaching strategies. The synergistic mechanism is mainly reflected in the following two aspects: (1) Synergistic effect of physical structure pretreatment and leaching reaction Microwave pyrolysis and cold quenching treatment induce thermal stress and phase transformation stress within mineral particles, forming a well-developed microcrack network. The cold quenching process, by rapidly fixing thermal stress, effectively suppresses microcrack closure and may introduce lattice defects, collectively increasing the specific surface area and pore connectivity of the solid. This structural modification provides an efficient mass transfer channel for the leaching agent, significantly improving reaction kinetics. Building upon this, the grinding process further optimizes the reaction interface: the first-stage grinding, based on microwave pretreatment, refines particles and dissociates minerals, exposing the encapsulated arsenic-containing phases; the second-stage grinding specifically disrupts the surface passivation layer formed after the first-stage leaching, creating an active interface for subsequent oxidation steps.

[0042] (2) This invention achieves selective leaching of different reactive phases through segmented leaching. The first stage of leaching mainly targets the arsenic phase with increased reactivity after physical activation, and bears the main arsenic removal load. The second stage of leaching focuses on treating residual arsenic with stable chemical properties or covered by a passivation layer. This functional grading achieves the adaptation of reaction conditions and phase characteristics, avoiding reagent waste and side reactions. In the second stage of leaching, grinding and enhanced oxidation constitute a synergistic unit with complementary mechanisms: grinding physically strips the passivation layer through mechanical force, exposing a fresh reaction interface; enhanced oxidation destroys the passivation layer composition and oxidizes insoluble arsenic minerals through chemical reagents. The synergistic effect of the two solves the diffusion restriction and surface repassivation problems caused by the passivation layer, ensuring the continuous and efficient operation of the second stage of leaching.

[0043] Compared with the prior art, the present invention provides a method for staged enhanced leaching removal of arsenic from high-arsenic copper ore, which has the following beneficial effects: (1) Microcracks are generated and maintained inside the mineral through the synergistic effect of microwave pyrolysis and specific additives, creating key conditions for subsequent deep arsenic removal; then, through two countercurrent alkaline leaching and intermediate oxidation processes, the mineral encapsulation and passivation layer are systematically broken, and arsenic in different occurrence states is removed.

[0044] (2) The present invention adopts microwave pyrolysis and quenching pretreatment method for high arsenic copper ore. During the pyrolysis process, unique combined reagents lime and sodium hydroxide are added to promote the formation of microcracks in the particles and increase the surface area of ​​high arsenic copper ore, which is conducive to a significant improvement in arsenic leaching efficiency.

[0045] (3) This invention enhances the selective and efficient leaching of arsenic in high-arsenic copper ore through a staged enhanced leaching process that combines staged grinding leaching, leaching residue enhanced oxidation, and staged stirring leaching. This invention has significant advantages such as high arsenic removal rate, good selectivity, and thorough reaction, providing a reliable technical path for the clean and efficient utilization of high-arsenic copper ore, a difficult-to-process resource.

[0046] (4) In the process of this invention, the closed-loop circulation of the leachate achieves material balance and process enhancement. This design continuously enriches the arsenic concentration through liquid phase circulation, creating favorable conditions for the subsequent targeted recovery of arsenic. At the same time, the residual effective components in the returned liquid can maintain the chemical balance of the system and reduce the consumption of fresh leachate. This mode significantly reduces the amount of waste liquid discharged and the treatment load, embodies the principle of clean production, and together with the front-end pretreatment and leaching unit, it constitutes a complete process system that is efficient and environmentally friendly. Attached Figure Description

[0047] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] In the embodiments and comparative examples of this invention, the concentration of sodium sulfide aqueous solution was 2.0 mol / L, the concentration of sodium hydroxide aqueous solution was 1.0 mol / L, the concentration of hydrogen peroxide aqueous solution was 9.8 mol / L, and the concentration of sodium chloride aqueous solution was 1.0 mol / L.

[0050] Example 1 In this embodiment, the arsenic-bearing minerals of the high-arsenic copper sulfide ore are mainly arsenic tetrahedrite, with a Cu grade of 15.72% and an As content of 10.30%. The ore sample contains small amounts of chalcocite, sphalerite, and siderite, and the gangue minerals are mainly quartz and calcite.

[0051] A method for staged enhanced leaching to remove arsenic from high-arsenic copper ore specifically includes the following steps: (1) The high-arsenic copper sulfide ore was crushed and screened by coarse, medium and fine crushers and roller crusher in sequence to obtain high-arsenic copper ore powder with a particle size of -1mm.

[0052] (2) Add limestone and sodium hydroxide to the high-arsenic copper ore powder obtained in step (1) and mix evenly. The amount of limestone added is 1.5% of the mass of the high-arsenic copper ore powder, and the amount of sodium hydroxide added is 1.0% of the mass of the high-arsenic copper ore powder. Then, microwave pyrolysis pretreatment is carried out for 5 minutes under the conditions of microwave power of 600W and temperature of 350℃. Then, the microwave-pyrolyzed high-arsenic copper ore is quenched in water at 20℃ to obtain the pretreated high-arsenic copper ore.

[0053] (3) Mix the high-arsenic copper ore pretreated in step (2) with sodium sulfide aqueous solution and sodium hydroxide aqueous solution to obtain a first-stage slurry A; the slurry concentration of the first-stage slurry A is 65wt%, the concentration of sodium sulfide in the first-stage slurry A is 1.5mol / L, and the concentration of sodium hydroxide is 0.5mol / L; then grind the first-stage slurry A until -0.074mm accounts for 75wt%, to obtain a first-stage grinding and leaching slurry.

[0054] (4) Add leaching agent to the first-stage grinding slurry obtained in step (3) and mix evenly to obtain a first-stage slurry B. The slurry concentration of the first-stage slurry B is 20wt%, the concentration of sodium sulfide in the first-stage slurry B is 1.0mol / L, and the concentration of sodium hydroxide is 0.3mol / L. Then, the first-stage slurry B is stirred and leached at 60℃ for 2h to obtain a stirred leaching slurry.

[0055] (5) The leaching slurry obtained in step (4) is concentrated and dehydrated until the bottom slurry concentration is 60wt%, resulting in a leaching solution and a leaching residue. The leaching solution is returned to step (3).

[0056] (6) Add sodium sulfide aqueous solution and sodium hydroxide aqueous solution to the first leaching residue obtained in step (5), mix evenly to obtain second slurry A. The slurry concentration of second slurry A is 65wt%, the concentration of sodium sulfide in second slurry A is 1.5mol / L, and the concentration of sodium hydroxide is 0.8mol / L. Then grind second slurry A until the fineness is 0.074mm accounting for 95wt% to obtain second grinding and leaching slurry.

[0057] (7) Add the mixed reagents hydrogen peroxide aqueous solution and sodium chloride aqueous solution to the two-stage grinding and leaching slurry obtained in step (6) and mix evenly to obtain a mixed slurry. The slurry concentration of the mixed slurry is 10wt%, the concentration of hydrogen peroxide in the mixed slurry is 1.0mol / L, and the concentration of sodium chloride is 0.34mol / L. The mixed slurry is subjected to enhanced oxidation at 25℃ for 2.0h to obtain an oxidized slurry.

[0058] (8) Add sodium sulfide aqueous solution and sodium hydroxide aqueous solution to the oxidized slurry obtained in step (7) and mix evenly to obtain a second-stage slurry B. The slurry concentration of the second-stage slurry B is 10wt%, the concentration of sodium sulfide in the second-stage slurry B is 1.5mol / L, and the concentration of sodium hydroxide is 0.5mol / L. Then, the second-stage slurry B is stirred and leached at 90℃ for 2h to obtain a second-stage stirred leaching slurry.

[0059] (9) The two-stage stirred leaching slurry obtained in step (8) is filtered to obtain a two-stage alkaline leaching solution and a two-stage leaching residue. The two-stage alkaline leaching solution is returned to the two-stage grinding leaching in step (6). The two-stage leaching residue is washed with water until the pH of the washing solution is 6-7, and a filter cake is obtained. The filter cake is high copper slag after arsenic removal.

[0060] Example 2 In this embodiment, the arsenic-bearing minerals of the high-arsenic copper sulfide ore are mainly chalcopyrite, with a Cu grade of 12.13% and an As content of 9.06%. The ore sample contains a small amount of chalcopyrite, and the gangue minerals are mainly quartz and calcite.

[0061] A method for staged enhanced leaching to remove arsenic from high-arsenic copper ore specifically includes the following steps: (1) The high-arsenic copper sulfide ore was crushed and screened by coarse, medium and fine crushers and roller crusher in sequence to obtain high-arsenic copper ore powder with a particle size of -1mm.

[0062] (2) Add limestone and sodium hydroxide to the high-arsenic copper ore powder obtained in step (1) and mix evenly. The amount of limestone added is 1.0% of the mass of the high-arsenic copper ore powder, and the amount of sodium hydroxide added is 0.5% of the mass of the high-arsenic copper ore powder. Then, microwave pyrolysis pretreatment is carried out for 3 minutes under the conditions of microwave power of 500W and temperature of 300℃. Then, the microwave-pyrolyzed high-arsenic copper ore is quenched in water at 25℃ to obtain the pretreated high-arsenic copper ore.

[0063] (3) Mix the high-arsenic copper ore pretreated in step (2) with sodium sulfide aqueous solution and sodium hydroxide aqueous solution to obtain a first-stage slurry A; the slurry concentration of the first-stage slurry A is 60 wt%, the concentration of sodium sulfide in the first-stage slurry A is 1.0 mol / L, and the concentration of sodium hydroxide is 0.2 mol / L; then grind the first-stage slurry A to -0.074 mm accounting for 70 wt%, to obtain a first-stage grinding and leaching slurry.

[0064] (4) Add leaching agent to the first-stage grinding and leaching slurry obtained in step (3) and mix evenly to obtain a first-stage slurry B. The slurry concentration of the first-stage slurry B is 25wt%, the concentration of sodium sulfide in the first-stage slurry B is 0.5mol / L, and the concentration of sodium hydroxide is 0.1mol / L. Then, the first-stage slurry B is stirred and leached at 50℃ for 3h to obtain a stirred leaching slurry.

[0065] (5) The leaching slurry obtained in step (4) is concentrated and dehydrated until the bottom slurry concentration is 65wt%, resulting in a leaching solution and a leaching residue. The leaching solution is returned to step (3).

[0066] (6) Add sodium sulfide aqueous solution and sodium hydroxide aqueous solution to the first leaching residue obtained in step (5), mix evenly to obtain second slurry A. The slurry concentration of second slurry A is 62wt%, the concentration of sodium sulfide in second slurry A is 1.0mol / L, and the concentration of sodium hydroxide is 0.5mol / L. Then grind second slurry A until the fineness is 0.074mm accounting for 90wt% to obtain second grinding and leaching slurry.

[0067] (7) Add the mixed reagents hydrogen peroxide aqueous solution and sodium chloride aqueous solution to the two-stage grinding and leaching slurry obtained in step (6) and mix evenly to obtain a mixed slurry. The slurry concentration of the mixed slurry is 15wt%, the concentration of hydrogen peroxide in the mixed slurry is 0.5mol / L, and the concentration of sodium chloride is 0.3mol / L. The mixed slurry is subjected to enhanced oxidation at 20℃ for 1.5h to obtain an oxidized slurry.

[0068] (8) Add sodium sulfide aqueous solution and sodium hydroxide aqueous solution to the oxidized slurry obtained in step (7) and mix evenly to obtain a second-stage slurry B. The slurry concentration of the second-stage slurry B is 15wt%, the concentration of sodium sulfide in the second-stage slurry B is 1.0mol / L, and the concentration of sodium hydroxide is 0.3mol / L. Then, the second-stage slurry B is stirred and leached at 80℃ for 3h to obtain a second-stage stirred leaching slurry.

[0069] (9) The two-stage stirred leaching slurry obtained in step (8) is filtered to obtain a two-stage alkaline leaching solution and a two-stage leaching residue. The two-stage alkaline leaching solution is returned to the two-stage grinding leaching in step (6). The two-stage leaching residue is washed with water until the pH of the washing solution is 6-7, and a filter cake is obtained. The filter cake is high copper slag after arsenic removal.

[0070] Example 3 In this embodiment, the arsenic-bearing minerals of the high-arsenic copper sulfide ore are mainly chalcopyrite, with a Cu grade of 13.76% and an As content of 9.81%. The ore sample contains a small amount of chalcopyrite, and the gangue minerals are mainly quartz and calcite.

[0071] A method for staged enhanced leaching to remove arsenic from high-arsenic copper ore specifically includes the following steps: (1) The high-arsenic copper sulfide ore was crushed and screened by coarse, medium and fine crushers and roller crusher in sequence to obtain high-arsenic copper ore powder with a particle size of -1mm.

[0072] (2) Add limestone and sodium hydroxide to the high-arsenic copper ore powder obtained in step (1) and mix evenly. The amount of limestone added is 1.2% of the mass of the high-arsenic copper ore powder, and the amount of sodium hydroxide added is 0.6% of the mass of the high-arsenic copper ore powder. Then, microwave pyrolysis pretreatment is carried out for 4 minutes under the conditions of microwave power of 550W and temperature of 320℃. Then, the microwave-pyrolyzed high-arsenic copper ore is quenched in water at 25℃ to obtain the pretreated high-arsenic copper ore.

[0073] (3) Mix the high-arsenic copper ore pretreated in step (2) with sodium sulfide aqueous solution and sodium hydroxide aqueous solution to obtain a first-stage slurry A; the slurry concentration of the first-stage slurry A is 62wt%, the concentration of sodium sulfide in the first-stage slurry A is 1.2mol / L, and the concentration of sodium hydroxide is 0.3mol / L; then grind the first-stage slurry A until -0.074mm accounts for 72wt%, to obtain a first-stage grinding and leaching slurry.

[0074] (4) Add leaching agent to the first-stage grinding slurry obtained in step (3) and mix evenly to obtain a first-stage slurry B. The slurry concentration of the first-stage slurry B is 22wt%, the concentration of sodium sulfide in the first-stage slurry B is 0.8mol / L, and the concentration of sodium hydroxide is 0.2mol / L. Then, the first-stage slurry B is stirred and leached at 55℃ for 2.5h to obtain a stirred leaching slurry.

[0075] (5) The leaching slurry obtained in step (4) is concentrated and dehydrated until the bottom slurry concentration is 62wt%, resulting in a leaching solution and a leaching residue. The leaching solution is returned to step (3).

[0076] (6) Add sodium sulfide aqueous solution and sodium hydroxide aqueous solution to the first leaching residue obtained in step (5), mix evenly to obtain second slurry A. The slurry concentration of second slurry A is 60 wt%, the concentration of sodium sulfide in second slurry A is 1.2 mol / L, and the concentration of sodium hydroxide is 0.6 mol / L. Then grind second slurry A until the fineness is 0.074 mm, accounting for 92 wt%, to obtain second grinding and leaching slurry.

[0077] (7) Add the mixed reagents hydrogen peroxide aqueous solution and sodium chloride aqueous solution to the two-stage grinding and leaching slurry obtained in step (6) and mix evenly to obtain a mixed slurry. The slurry concentration of the mixed slurry is 12wt%, the concentration of hydrogen peroxide in the mixed slurry is 0.7mol / L, and the concentration of sodium chloride is 0.32mol / L. The mixed slurry is subjected to enhanced oxidation at 22℃ for 1.75h to obtain an oxidized slurry.

[0078] (8) Add sodium sulfide aqueous solution and sodium hydroxide aqueous solution to the oxidized slurry obtained in step (7) and mix evenly to obtain a second-stage slurry B. The slurry concentration of the second-stage slurry B is 12wt%, the concentration of sodium sulfide in the second-stage slurry B is 1.2mol / L, and the concentration of sodium hydroxide is 0.4mol / L. Then, the second-stage slurry B is stirred and leached at 85℃ for 2.5h to obtain a second-stage stirred leaching slurry.

[0079] (9) The two-stage stirred leaching slurry obtained in step (8) is filtered to obtain a two-stage alkaline leaching solution and a two-stage leaching residue. The two-stage alkaline leaching solution is returned to the two-stage grinding leaching in step (6). The two-stage leaching residue is washed with water until the pH of the washing solution is 6-7, and a filter cake is obtained. The filter cake is high copper slag after arsenic removal.

[0080] Comparative Example 1 In this comparative example, the arsenic-bearing minerals of the high-arsenic copper sulfide ore are mainly arsenic tetrahedrite, with a Cu grade of 15.72% and an As content of 10.30%. The ore sample contains small amounts of chalcocite, sphalerite, and siderite, while the gangue minerals are mainly quartz and calcite.

[0081] A method for direct alkaline leaching to remove arsenic specifically includes the following steps: (1) The high-arsenic copper sulfide ore is crushed and ground until -0.074 mm accounts for 95 wt%, and high-arsenic copper ore powder is obtained.

[0082] (2) The high-arsenic copper ore powder obtained in step (1) is mixed evenly with the leaching agent sodium sulfide aqueous solution and sodium hydroxide aqueous solution to obtain a slurry; the liquid-solid ratio of the high-arsenic copper ore powder and the leaching agent in the slurry is 10L:1Kg, the concentration of sodium sulfide is 5.5mol / L, and the concentration of sodium hydroxide is 2.0mol / L; then, the leaching is stirred at 90℃ for 5h to obtain the stirred leaching slurry.

[0083] (3) The stirred leaching slurry obtained in step (2) is filtered to obtain alkaline leaching solution and leaching residue. The second-stage leaching residue is washed with water until the pH of the washing solution is 6-7, and the filter cake is obtained. The filter cake is high copper slag after arsenic removal.

[0084] Comparative Example 2 In this comparative example, the arsenic-bearing minerals of the high-arsenic copper sulfide ore are mainly chalcopyrite, with a Cu grade of 12.13% and an As content of 9.06%. The ore sample contains a small amount of chalcopyrite, and the gangue minerals are mainly quartz and calcite.

[0085] A method for direct alkaline leaching to remove arsenic specifically includes the following steps: (1) The high-arsenic copper sulfide ore is crushed and ground until -0.074 mm accounts for 95 wt%, and high-arsenic copper ore powder is obtained.

[0086] (2) The high-arsenic copper ore powder obtained in step (1) is mixed evenly with the leaching agent sodium sulfide aqueous solution and sodium hydroxide aqueous solution to obtain a slurry; the liquid-solid ratio of the high-arsenic copper ore powder and the leaching agent in the slurry is 10L:1Kg, the concentration of sodium sulfide is 5.5mol / L, and the concentration of sodium hydroxide is 2.0mol / L; then, the leaching is stirred at 90℃ for 5h to obtain the stirred leaching slurry.

[0087] (3) The stirred leaching slurry obtained in step (2) is filtered to obtain alkaline leaching solution and leaching residue. The second-stage leaching residue is washed with water until the pH of the washing solution is 6-7, and the filter cake is obtained. The filter cake is high copper slag after arsenic removal.

[0088] The high-copper slag obtained from Examples 1-3 and Comparative Examples 1-2 was tested, and the data are shown in Table 1 below.

[0089] Table 1 As shown in Table 1, for high-arsenic copper ore mainly composed of chrysoberyl ore, the ore sample contains 10.30% As. Using conventional alkaline leaching for arsenic removal, the arsenic content in the high-copper slag after arsenic removal is still relatively high, containing 2.11% arsenic, with an arsenic leaching rate of 80.42%. Using the enhanced leaching method of this invention, the arsenic content in the high-copper slag after arsenic removal is significantly reduced to 0.35%, and the arsenic leaching rate reaches 96.21%, which is 15.79% higher than that of conventional alkaline leaching. For high-arsenic copper ore mainly composed of chrysoberyl ore, the ore sample contains 9.06% As. Using conventional alkaline leaching for arsenic removal, the arsenic content in the high-copper slag after arsenic removal is 1.48%, with an arsenic leaching rate of 84.19%. Using the enhanced leaching method of this invention, the arsenic content in the leaching residue is only 0.23%, and the arsenic leaching rate reaches 97.54%, which is significantly higher than that of conventional alkaline leaching.

[0090] The process flow diagram of this invention is as follows: Figure 1 As shown, this invention employs a combined process of microwave pyrolysis, two-stage countercurrent alkaline leaching, and enhanced oxidation to achieve selective and efficient leaching of arsenic from high-arsenic copper ores. Through the synergistic effect of microwave pyrolysis and specific additives, microcracks are generated and maintained within the mineral, creating key conditions for subsequent deep arsenic removal. Subsequently, through two-stage countercurrent alkaline leaching and intermediate oxidation processes, the mineral encapsulation and passivation layers are systematically broken down, removing arsenic in different occurrence states. The method described in this invention has significant advantages such as high arsenic removal rate, good selectivity, and thorough reaction. It not only provides a reliable technical path for the clean and efficient utilization of high-arsenic copper ores, a difficult-to-process resource, but also has important significance for promoting the green and sustainable development of non-ferrous metal smelting.

[0091] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for staged enhanced leaching to remove arsenic from high-arsenic copper ore, characterized in that, Specifically, the following steps are included: (1) The high-arsenic copper ore is crushed and screened to obtain high-arsenic copper ore powder; (2) Add additives to the high-arsenic copper ore powder obtained in step (1) and mix evenly. Then, pretreat with microwave and quench to obtain pretreated high-arsenic copper ore. (3) Mix the pretreated high-arsenic copper ore from step (2) with the leaching agent to obtain a first-stage slurry A. Then grind the first-stage slurry A to obtain a first-stage grinding-leaching slurry. (4) Add leaching agent to the first section of grinding and leaching slurry obtained in step (3) and mix evenly to obtain a first section of slurry B. Then, stir and leach the first section of slurry B to obtain a stirred leaching slurry. (5) The first section of stirred leaching slurry obtained in step (4) is concentrated and dehydrated to obtain a first section of alkaline leaching solution and a first section of leaching residue. The first section of alkaline leaching solution is returned to step (3). (6) Add leaching agent to the first leaching residue obtained in step (5) and mix evenly to obtain second slurry A. Then grind the second slurry A to obtain second grinding and leaching slurry. (7) Add the mixed agent to the two-stage grinding and leaching slurry obtained in step (6) and mix evenly to obtain a mixed slurry. Then, perform enhanced oxidation on the mixed slurry to obtain an oxidized slurry. (8) Add leaching agent to the oxidized slurry obtained in step (7) and mix evenly to obtain two-stage slurry B. Then, perform two-stage stirring leaching on the two-stage slurry B to obtain two-stage stirring leaching slurry. (9) The two-stage stirred leaching slurry obtained in step (8) is filtered to obtain a two-stage alkaline leaching solution and a two-stage leaching residue. The two-stage alkaline leaching solution is returned to step (6). The two-stage leaching residue is washed and separated to obtain a filter cake. The filter cake is a high-copper slag after arsenic removal.

2. The method for staged enhanced leaching removal of arsenic from high-arsenic copper ore according to claim 1, characterized in that, The high-arsenic copper ore raw material mentioned in step (1) is arsenopyrite or arsenopyrite; the particle size of the high-arsenic copper ore powder is -1mm.

3. The method for staged enhanced leaching removal of arsenic from high-arsenic copper ore according to claim 1, characterized in that, The additives mentioned in step (2) are limestone and sodium hydroxide. The amount of limestone added is 1.0%-1.5% of the mass of the high-arsenic copper ore powder, and the amount of sodium hydroxide added is 0.5%-1.0% of the mass of the high-arsenic copper ore powder. The conditions for microwave pretreatment are: power of 500-600W, treatment time of 3-5min, and temperature of 300-350℃. The quenching is specifically: the microwave-pretreated high-arsenic copper ore is immersed in water at 20-25℃ for rapid cooling.

4. The method for staged enhanced leaching removal of arsenic from high-arsenic copper ore according to claim 1, characterized in that, The leaching agent in step (3) is composed of a mixture of sodium sulfide aqueous solution and sodium hydroxide aqueous solution, wherein the concentration of sodium sulfide aqueous solution is 2.0 mol / L and the concentration of sodium hydroxide aqueous solution is 1.0 mol / L; the concentration of sodium sulfide in slurry A is 1.0-1.5 mol / L and the concentration of sodium hydroxide is 0.2-0.5 mol / L; the slurry concentration of slurry A is 60-65 wt%; the grinding specifically refers to grinding to -0.074 mm, which accounts for 70-75 wt%.

5. The method for staged enhanced leaching removal of arsenic from high-arsenic copper ore according to claim 1, characterized in that, The leaching agent in step (4) is composed of a mixture of sodium sulfide aqueous solution and sodium hydroxide aqueous solution, wherein the concentration of sodium sulfide aqueous solution is 2.0 mol / L and the concentration of sodium hydroxide aqueous solution is 1.0 mol / L; the concentration of sodium sulfide in slurry B is 0.5-1.0 mol / L and the concentration of sodium hydroxide is 0.1-0.3 mol / L; the slurry concentration of slurry B is 20-25 wt%; the conditions for the first stage of stirring leaching are: stirring leaching at 50-60℃ for 2-3 hours.

6. The method for staged enhanced leaching removal of arsenic from high-arsenic copper ore according to claim 1, characterized in that, The conditions for concentration and dewatering in step (5) are: concentration and dewatering until the underflow slurry concentration is 60-65 wt%.

7. The method for staged enhanced leaching removal of arsenic from high-arsenic copper ore according to claim 1, characterized in that, The leaching agent solution in step (6) is composed of a mixture of sodium sulfide aqueous solution and sodium hydroxide aqueous solution, wherein the concentration of sodium sulfide aqueous solution is 2.0 mol / L and the concentration of sodium hydroxide aqueous solution is 1.0 mol / L; the concentration of sodium sulfide in the second-stage slurry A is 1.0-1.5 mol / L and the concentration of sodium hydroxide is 0.5-0.8 mol / L; the slurry concentration of the second-stage slurry A is 60-65 wt%; the grinding specifically refers to grinding to -0.074 mm, which accounts for 90-95 wt%.

8. The method for staged enhanced leaching removal of arsenic from high-arsenic copper ore according to claim 1, characterized in that, The mixed reagent in step (7) is composed of a mixture of hydrogen peroxide aqueous solution and sodium chloride aqueous solution, wherein the concentration of hydrogen peroxide aqueous solution is 9.8 mol / L and the concentration of sodium chloride aqueous solution is 1.0 mol / L; the concentration of hydrogen peroxide in the mixed slurry is 0.5-1.0 mol / L and the concentration of sodium chloride is 0.3-0.34 mol / L; the concentration of the oxidized slurry is 10-15 wt%; the conditions for enhanced oxidation are: oxidation at 20-25℃ for 1.5-2 h.

9. The method for staged enhanced leaching removal of arsenic from high-arsenic copper ore according to claim 1, characterized in that, The leaching agent in step (8) is composed of a mixture of sodium sulfide aqueous solution and sodium hydroxide aqueous solution, wherein the concentration of sodium sulfide aqueous solution is 2.0 mol / L and the concentration of sodium hydroxide aqueous solution is 1.0 mol / L; the concentration of sodium sulfide in the second-stage slurry B is 0.5-1.0 mol / L and the concentration of sodium hydroxide is 0.1-0.3 mol / L; the slurry concentration of the second-stage slurry B is 10-15 wt%; the conditions for the second-stage stirring leaching are: stirring leaching at 50-60℃ for 2-3 hours.

10. The method for staged enhanced leaching removal of arsenic from high-arsenic copper ore according to claim 1, characterized in that, The washing conditions described in step (9) are: washing with water until the pH of the washing solution is 6-7.

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