Method for collaboratively leaching copper metal from copper oxide concentrate acid leaching residue and copper sulfide concentrate roasted sand acid leaching residue

Abstract

The present invention discloses a method for synergistically leaching copper metal using acid leaching residues from copper oxide concentrate and acid leaching residues from roasted copper sulfide concentrate. The method comprises: mixing the acid leaching residues from copper oxide concentrate and the acid leaching residues from roasted copper sulfide concentrate in a mass ratio of (7-6):(3-4) to obtain a mixed slag material; stirring and mixing the obtained mixed slag material with a leaching agent to obtain a slurry; sequentially subjecting the obtained slurry to heating leaching and oxidative leaching; and finally subjecting the obtained slurry to solid-liquid separation, extracting the separated leachate to obtain a loaded organic phase and a raffinate; and stripping and electrowinning the obtained loaded organic phase to obtain metallic copper. The present invention first heats and synergizes the acid leaching residues from copper oxide concentrate and roasted copper sulfide concentrate, and then adds a strong oxidant to further oxidatively leach the copper metal in the two mixed slag slurries, ultimately achieving a leaching rate of over 88%.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy, in particular to a method for collaboratively leaching copper metal using acid leaching residues from copper oxide concentrate and acid leaching residues from roasted copper sulfide concentrate. Background Art

[0002] Currently, copper ore in Africa, particularly in the Democratic Republic of the Congo, is primarily a mixture of sulfide and oxide ores. Due to the complex physical and chemical properties of these mixed ores, most mixed ore processing processes involve sulfur-first, followed by oxygen flotation to produce copper oxide concentrate and copper sulfide concentrate. The copper oxide concentrate enters the hydrometallurgical system, while the copper sulfide concentrate undergoes roasting to produce roasted sand, which then enters the hydrometallurgical system. During this sulfur-first, followed by oxygen flotation process, due to the fine or uneven distribution of the minerals, copper oxide and copper sulfide minerals coexist during flotation. The copper oxide concentrate contains sulfide minerals that cannot be extracted by conventional wet leaching methods. Furthermore, the roasted sand produced after roasting the copper sulfide concentrate contains incompletely oxidized sulfide copper minerals. Consequently, the wet acid leaching residues from both concentrates contain a large amount of unrecovered copper metal.

[0003] The copper grade in acid leaching residue from low-grade copper oxide concentrate is typically 2%-4%. This is the leaching residue obtained after leaching the copper oxide concentrate product produced from a complex mixed ore using a process that first flots copper sulfide and then flots copper oxide. The copper grade in acid leaching residue from roasted copper sulfide concentrate is typically 4%-8%. This is the acid leaching residue obtained after secondary leaching of the roasted calcined high-grade copper sulfide concentrate. Currently, the separate processing of these low-grade acid leaching residues is difficult, and most of them are dumped in slag dumps, causing environmental pollution and resulting in a significant waste of copper resources. However, copper is a non-renewable resource, and with continued mining and consumption, reserves are gradually decreasing. Existing processes have increasingly prominent problems in processing "poor, fine, and mixed" ores. Therefore, recovering copper from complex, low-grade acid leaching residues has become a significant challenge and an important development direction for the industry.

[0004] Currently, hydrometallurgical methods for treating complex, low-grade copper oxide acid leaching residues and copper sulfide concentrate roasted acid leaching residues, primarily focus on flotation-enriched concentrates followed by pyrometallurgical smelting, pressure leaching, chloride leaching, ammonia leaching, and bioleaching. However, flotation-fired processes require higher concentrate grades and stricter impurity content requirements, resulting in complex processes, large infrastructure investments, and high energy consumption. Pressure leaching also has the problems of complex process, large investment, high energy consumption, high requirements for equipment performance, and high investment and risk in production operation safety management; the chloride salt leaching process can only process copper minerals with a Cu grade of more than 25%. The solid-liquid separation volume is large in the entire process. The chloride ions introduced into the system during the treatment process will affect the quality of the cathode copper and accelerate equipment corrosion, and high requirements are placed on the equipment's anti-corrosion performance; ammonia leaching is harmful to the human body and seriously pollutes the environment, and requires large environmental protection investment; bioleaching, also known as biometallurgy, is the product of the cross-use of microbiology and hydrometallurgical technology, but microorganisms must first be domesticated or induced to leach effectively, and because the bacterial community is difficult to cultivate, the cycle is long, the leaching rate is low, and it is restricted by multiple conditions such as geographical conditions, natural environment and ore properties, making it difficult to apply on a large scale in my country.

[0005] In view of the multiple conditions limiting the extraction of copper by the above-mentioned treatment processes, and the fact that there is currently no better treatment process for low-grade copper oxide concentrate acid leaching residue and copper sulfide concentrate roasted sand acid leaching residue with complex structure and coexistence of multiple elements, copper oxide concentrate acid leaching residue and copper sulfide concentrate roasted sand acid leaching residue are difficult to recover copper metal from and are therefore stored or abandoned in large quantities, resulting in a waste of copper resources and bringing great pressure on the environmental protection. Summary of the Invention

[0006] The present invention provides a method for leaching copper metal by cooperating acid leaching residues of copper oxide concentrate and acid leaching residues of roasted copper sulfide concentrate, so as to solve the technical problem in the prior art that low-grade acid leaching residues of copper oxide concentrate and roasted copper sulfide concentrate are difficult to recover copper metal from and thus are stored or abandoned in large quantities, resulting in waste of copper resources and environmental pollution.

[0007] According to one aspect of the present invention, a method for collaboratively leaching copper metal using copper oxide concentrate acid leaching residue and copper sulfide concentrate roasted acid leaching residue is provided, wherein the copper oxide concentrate acid leaching residue has a Cu grade of 2-4%, and the copper sulfide concentrate roasted acid leaching residue has a Cu grade of 4-8%. The method comprises the following steps:

[0008] (1) mixing the acid leaching residue of copper oxide concentrate and the acid leaching residue of copper sulfide concentrate roasted sand in a mass ratio of (7-6):(3-4) to obtain a mixed slag material;

[0009] (2) stirring and mixing the obtained mixed slag material with a leaching agent to obtain a slurry, wherein the leaching agent is a sulfuric acid solution system leaching agent; the mass concentration of the obtained slurry is 15-17%;

[0010] (3) heating and leaching the obtained slurry, wherein the leaching temperature is 80-90° C.;

[0011] (4) After the heating leaching is completed, an oxidant is added to perform oxidative leaching to obtain a leached slurry;

[0012] (5) performing solid-liquid separation on the obtained leaching slurry to obtain leaching residue and leachate;

[0013] (6) washing the obtained leaching residue to obtain washing residue and washing liquid; extracting the obtained leaching liquid to obtain a loaded organic phase and a raffinate, wherein the obtained washing liquid is used in the extraction step, and the obtained washing residue is discharged for tail treatment; the raffinate obtained by the extraction is used to prepare the sulfuric acid solution system leaching agent;

[0014] (7) The obtained loaded organic phase is subjected to back extraction and electrolysis to obtain metallic copper.

[0015] Furthermore, in step (3), the initial concentration of the leaching agent in the slurry is 180-220 g / L.

[0016] Furthermore, the leaching time of the heated leaching in step (3) is 4-6 hours.

[0017] Furthermore, the leaching rate of the heated leaching in step (3) is not less than 80%.

[0018] Furthermore, the leaching time of the oxidative leaching in step (4) is 2-3 hours.

[0019] Furthermore, the leaching rate of the oxidative leaching in step (4) is not less than 88%.

[0020] Furthermore, the oxidant added in step (4) includes hematite or magnetite.

[0021] Furthermore, the amount of hematite added to the mixed slag is 4-8 kg / t.

[0022] Furthermore, the solid-liquid separation in step (5) also includes concentrating the leached slurry.

[0023] Furthermore, the washing of the obtained leaching residue in step (6) includes stirring and washing the obtained leaching residue with clean water having a pH of 6.5-7.5 under natural conditions.

[0024] The present invention has the following beneficial effects:

[0025] The present invention performs a heating collaborative leaching on the copper oxide concentrate acid leaching residue and the copper sulfide concentrate roasted sand acid leaching residue, and then adds a strong oxidant to continue oxidative leaching of the copper metal in the two mixed slag slurries, and finally obtains a leaching rate of more than 88% of the technical indicator.

[0026] The essence of the strong oxidation step-by-step synergistic treatment process proposed in this invention is to perform synergistic leaching on the acid leaching residue of copper oxide concentrate and the acid leaching residue of roasted copper sulfide concentrate. After the synergistic leaching is complete, a strong oxidant is added to continuously enhance the leaching of copper metal in the slag that has been fully exposed but has not yet reacted due to insufficient oxidation. The leaching system consists of the acid leaching residue of copper oxide concentrate, the acid leaching residue of roasted copper sulfide concentrate, a strong oxidant, sulfuric acid, an aqueous phase, and a gas phase. At a temperature of 80-90°C, the difficult-to-leach copper and other valuable metals in the materials are continuously converted into soluble sulfates, which enter the solution in ionic form for recovery.

[0027] This collaborative treatment process is highly practical for low-grade copper oxide concentrate acid leaching residue and copper sulfide concentrate roasted sand acid leaching residue with complex mineral composition and variable properties, effectively realizing the collaborative treatment of the two, and further improving the leaching efficiency through two-stage strong oxidation leaching, with low leaching cost, good recovery effect, and simple and mature subsequent treatment process. By performing the above treatment on the complex low-grade copper oxide concentrate acid leaching residue and copper sulfide concentrate roasted sand acid leaching residue, the copper content in the final leaching residue is greatly reduced, thereby reducing the large-scale storage and waste of leaching tailings generated during the mining and processing of copper products.

[0028] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0030] Figure 1 This is a process flow chart for processing low-grade copper-cobalt mixed ore in an embodiment of the present invention;

[0031] Figure 2 The present invention is a process flow chart of the coordinated leaching of copper metal using acid leaching residues from copper oxide concentrate and acid leaching residues from roasted copper sulfide concentrate according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the invention purpose, technical scheme and beneficial technical effect of the present invention clearer, the present invention is further described in detail below with reference to the embodiments. It should be understood that the embodiments described in this specification are only for explaining the present invention and are not intended to limit the present invention.

[0033] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and similarly, any upper limit can be combined with any other upper limit to form an unspecified range. In addition, although not explicitly stated, each point or individual value between the endpoints of a range is included in the range. Thus, each point or individual value can serve as its own lower limit or upper limit and be combined with any other point or individual value, or with other lower limits or upper limits, to form an unspecified range.

[0034] In the description of this article, it should be noted that, unless otherwise specified, "above" and "below" are inclusive of the number itself, and the "multiple" in "one or more" means two or more, and the "multiple" in "one or more" means two or more.

[0035] An embodiment of the present invention provides a method for collaboratively leaching copper metal using copper oxide concentrate acid leaching residue and copper sulfide concentrate roasted acid leaching residue, wherein the copper oxide concentrate acid leaching residue has a Cu grade of 2-4%, and the copper sulfide concentrate roasted acid leaching residue has a Cu grade of 4-8%. The method comprises the following steps:

[0036] (1) mixing the acid leaching residue of copper oxide concentrate and the acid leaching residue of copper sulfide concentrate roasted sand in a mass ratio of (7-6):(3-4) to obtain a mixed slag material;

[0037] (2) stirring and mixing the obtained mixed slag material with a leaching agent to obtain a slurry, wherein the leaching agent is a sulfuric acid solution system leaching agent; the mass concentration of the obtained slurry is 15-17%;

[0038] (3) heating and leaching the obtained slurry, wherein the leaching temperature is 80-90° C.;

[0039] (4) After the heating leaching is completed, an oxidant is added to perform oxidative leaching to obtain a leached slurry;

[0040] (5) performing solid-liquid separation on the obtained leaching slurry to obtain leaching residue and leachate;

[0041] (6) washing the obtained leaching residue to obtain washing residue and washing liquid; extracting the obtained leaching liquid to obtain a loaded organic phase and a raffinate, wherein the obtained washing liquid is used in the extraction step, and the obtained washing residue is discharged for tail treatment; the raffinate obtained by the extraction is used to prepare the sulfuric acid solution system leaching agent;

[0042] (7) The obtained loaded organic phase is subjected to back extraction and electrolysis to obtain metallic copper.

[0043] In the embodiments of the present application, the "copper sulfide concentrate roasted sand acid leaching residue" is a copper sulfide concentrate with a copper grade of 60-70% obtained by flotation of a copper-cobalt mixed ore with a grade of 2-4% through a process of first flotation of copper sulfide and then flotation of copper oxide. The copper sulfide concentrate is subjected to oxidation roasting and partial acid roasting to obtain roasted sand with a grade of 50-60%. The roasted sand is subjected to a sulfuric acid leaching process to obtain the final copper sulfide concentrate roasted sand acid leaching residue. The copper grade of the copper sulfide concentrate roasted sand acid leaching residue is 4-8%.

[0044] In the embodiments of the present application, the "copper oxide concentrate acid leaching residue" is a copper oxide concentrate with a copper grade of 15-25% obtained by flotation of a copper-cobalt mixed ore with a grade of 2-4% through a process of first flotation of copper sulfide and then flotation of copper oxide. The copper oxide concentrate is subjected to a sulfuric acid leaching process to obtain the final copper oxide concentrate acid leaching residue, wherein the copper grade in the copper oxide concentrate acid leaching residue is about 2-4%.

[0045] According to a typical embodiment of the present invention, the production method of the copper sulfide concentrate roasted acid leaching residue and the copper oxide concentrate acid leaching residue is as follows: Figure 1 shown. Figure 1 The simple production process of acid leaching residue of roasted copper sulfide concentrate and acid leaching residue of copper oxide concentrate is shown.

[0046] In the embodiment of the present application, step (4) heats and leaches the obtained slurry, wherein the leaching temperature is 80-90°C, preferably 85°C. The leaching effect of the slurry is best when the leaching temperature is 80-90°C. A temperature below 80°C cannot meet the reaction requirements, and a temperature above 90°C may cause the slurry to boil, making it impossible to effectively control production.

[0047] In the embodiment of the present application, the heated leaching process is heated using high-temperature steam generated by the roasting furnace preheating boiler. The use of high-temperature steam for heated leaching can recycle the high-temperature steam, thereby achieving energy-saving and environmental protection.

[0048] In the embodiments of the present application, the oxidant added in step (4) includes hematite or magnetite. The reason for selecting hematite as the oxidant is that the ferric oxide in hematite contains ferric iron, which is the iron ion, and the redox reaction is the best. In addition, magnetite can also be used as the oxidant. The ferric oxide in magnetite contains both ferrous iron and ferric iron, but the amount of magnetite required to be added is greater than that of hematite.

[0049] In some embodiments, the amount of hematite added to the mixed slag is 4-8 kg / t, preferably 5 kg / t. If the amount of hematite is less than 4 kg / t, the redox reaction is incomplete and the leaching rate is low; if the amount of hematite is greater than 8 kg / t, it will result in waste of hematite.

[0050] In the embodiments of the present application, the leaching system used for the coordinated leaching includes: a slurry mixing and feeding system, a slurry mixing system, a heating system, a wet treatment system consisting of a leaching reaction tank and a filtration-washing system, etc.

[0051] According to the embodiments of the present application, the leaching raw material in the heated leaching process is the unenriched acid leaching residue of the copper oxide concentrate, which saves the flotation process of the leaching residue. The present application also creatively introduces an oxidation leaching step after the heated leaching, so that the leaching effect is further enhanced, and the final leaching rate can reach more than 88%.

[0052] In the embodiments of the present application, Figure 2 As shown, the method for leaching copper metal by cooperating acid leaching residues of copper oxide concentrate and acid leaching residues of roasted copper sulfide concentrate comprises the following steps:

[0053] Mix the acid leaching residue of copper oxide concentrate (70-80% -0.074mm particle size) and the roasted acid leaching residue of copper sulfide concentrate in a ratio of 7:3 or 6:4. Transfer the mixed ore sample to a slurry mixing tank, add the prepared leaching agent, and stir thoroughly to mix the slurry. The prepared slurry is then transferred to the leaching tank via a feed valve and a horizontal slurry pump. A solid-to-liquid ratio of 1:5 is used. Open the steam valve. Steam is introduced to increase the temperature, maintaining the leaching tank temperature at 80-90°C (optimally 85°C) using a digital temperature controller. Leaching is performed using a stirrer. After leaching for 4-6 hours, oxidant is added to the tank and leaching continues with stirring until the leaching reaction is complete.

[0054] Under the above conditions, valuable metallic copper, mainly found in minerals such as chrysocolla, chalcanthite, copper ferrite, copper ferrite, covellite, and bornite, reacts with other substances in quartz, gypsum, magnetite, kaolinite, muscovite, chlorite, and rutile in the mixed acid leaching residue, entering the solution in ionic form and converting into soluble sulfate. The main reactions occurring in the synergistic leaching process are as follows:

[0055] (1) Main chemical reactions of synergistic leaching:

[0056] Cu2O·Fe2O3 and CuFe2O4 in the ore undergo the following reaction in an aqueous solution of sulfuric acid:

[0057] 2Cu2O·Fe2O3+4H2SO4+O2=4CuSO4+2Fe2O3+4H2O (1)

[0058] CuO·Fe2O3+H2SO4=CuSO4+Fe2O3+H2O (2)

[0059] CuFe2O4+H2SO4+2H2O=CuSO4+2Fe(OH)3 (3)

[0060] CuFe2O4+H2SO4=CuSO4+Fe2O3+H2O (4)

[0061] Sulfides such as CuS in the ore are converted into Fe by the reaction of Cu2O·Fe2O3 and CuFe2O4 with sulfuric acid. 3+ Oxidation, regeneration of S o 、Cu 2+ , Fe 3+ It is reduced to Fe 2+ The overall reaction during the leaching process is as follows:

[0062] 2CuS+2H2SO4+O2=2CuSO4+2S+2H2O (5)

[0063] The specific reaction process of CuS in the acid leaching residue of copper oxide concentrate in the solution is as follows:

[0064] CuS has an ionization equilibrium in solution:

[0065] CuS=Cu 2+ +S 2－ (6)

[0066] Ionized S 2－ The ions are converted into hydrosulfuric acid by the sulfuric acid in the system:

[0067] S 2－ +2H + =H2S (7)

[0068] Because hydrosulfuric acid is a weak acid, S 2－ Almost all of it exists in the form of hydrosulfuric acid. At the same time, hydrosulfuric acid is absorbed by Fe 3+ Oxidation of elemental sulfur:

[0069] H2S+2Fe 3+ →2H + +S↓+2Fe 2+ (8)

[0070] The generated elemental sulfur easily appears in the form of colloid, because the sulfur colloid can absorb the hydrogen sulfide ions HS in the solution. － The negative charge, combined with the adsorption of the micelle itself, causes a considerable amount of Fe to be adsorbed on the surface of the sulfur micelle. 2+ ions, Fe 2+ It reacts with the oxygen dissolved into the solution during the stirring process to generate Fe 3+ :

[0071] 4Fe 2+ +4H + +O2→4Fe 3+ +2H2O (9)

[0072] Fe generated 3+ Continue to oxidize elemental S to HSO 3－ , H2SO3 and a small amount of SO3 2－ :

[0073] S+4Fe 3+ +3H2O→H2SO3+4Fe 2+ +4H + (10)

[0074] H2SO3 reacts with O2 dissolved in the solution to produce SO4 2－ :

[0075] 2H2SO3+O2→2SO4 2－ +4H + (11)

[0076] (2) Second stage strong oxidation leaching chemical reaction:

[0077] The sulfides such as CuS in the ore that are not fully reacted by the co-leaching are added to the Fe2O3 in the hematite powder and react with sulfuric acid to produce Fe 3+ Oxidation, the redox reaction is circulated again, further converting the CuS that has been fully exposed but not fully converted due to insufficient oxidation into CuSO4

[0078] (3) During the leaching process, steam heating can promote the redox reaction. At the same time, the O2 introduced by steam heating also plays a good oxidizing role. The leaching agent and materials are placed in the leaching tank and stirred at the same time. Through the enhanced heating method, the acid leaching residue of copper oxide concentrate and the acid leaching residue of copper sulfide concentrate roasted sand are synergistically leached. Sulfur is produced as elemental sulfur and sulfate. The leaching process completely eliminates the emission of SO2, H2S, and NOX vapor, and also improves the synergistic leaching rate of Cu metal in the two.

[0079] The present invention uses copper oxide concentrate acid leaching residue and copper sulfide concentrate roasted acid leaching residue as synergistic leaching raw materials, fundamentally solving the high cost and investment challenges associated with processing these residues separately. Leaching is performed at 80-90°C. Compared to other processes such as flotation-fired leaching, high-temperature roasting, oxygen pressure leaching, ammonia leaching, and bioleaching, this method significantly improves process safety while saving energy and environmental investment.

[0080] In some embodiments, the entire leaching process takes 6-9 hours. When the leaching time reaches 6-9 hours, the operation is stopped and the mixed slurry after leaching is fed to a thickener using a slurry pump for concentration and liquid-solid separation.

[0081] The filter residue contains iron, manganese, calcium, silicon, etc. It is washed with clean water with a pH of 6.5-7.5 under natural conditions. After washing, the slurry is fed into the filter press again. The washing liquid is mixed with the leachate and fed into the next process. The leachate residue is sent to the slag yard for storage.

[0082] The present invention provides a method for co-processing and recovering valuable copper from copper oxide concentrate acid leaching residue and copper sulfide concentrate roasted acid leaching residue. This treatment method is suitable for treating low-grade copper oxide concentrate acid leaching residue and copper sulfide concentrate roasted acid leaching residue. Low-grade copper oxide concentrate acid leaching residue contains copper ferrite, copper ferrite, chrysocolla, chalcocite, and trace amounts of copper-containing substances such as covellite, bornite, chalcopyrite, chalcocite, and thiothreite. Co-leaching of the copper oxide concentrate acid leaching residue and the copper sulfide concentrate roasted acid leaching residue can achieve a good copper recovery rate. High levels of impurities such as calcium, iron, cadmium, manganese, and phosphorus do not affect the leaching of copper metal during the co-leaching process, and the copper metal leaching rate can reach over 88%. Therefore, comprehensive recovery of copper resources from copper sulfide concentrate roasted acid leaching residue and copper oxide concentrate acid leaching residue can be achieved.

[0083] The collaborative processing method proposed in the present invention has very broad application prospects in the field of hydrometallurgy. It has the following characteristics that traditional processes do not have:

[0084] (1) Low-grade copper oxide concentrate acid leaching residue and copper sulfide concentrate roasted sand acid leaching residue are directly mixed to form a collaborative leaching material without any form of pretreatment.

[0085] (2) The different chemical components of the two slags were fully utilized to form a complementary reaction system, and the initial leaching reaction was completed in the same system;

[0086] (3) The addition of a strong oxidant in the second-stage leaching (oxidation leaching) helps to further improve the leaching effect of soluble copper caused by insufficient oxidation in the two slags;

[0087] (4) The material composition of the leaching process is simple. The high-temperature oxygen-rich ions carried in the steam during the steam heating process can play a good oxidizing role. The gas-liquid-solid three phases are evenly mixed in the leaching tank. The main oxide Fe 3+ Deoxidation leaching of Cu in the acid leaching residue of copper oxide concentrate reduces the consumption of oxidant and acid while the main metallic copper in the two is leached simultaneously.

[0088] (5) The small amount of oxidant added during the second stage strong oxidation leaching process is hematite powder which is easily available on the market, which does not increase the production cost too much;

[0089] (6) The synergistic leaching process is carried out in a closed container at a moderate temperature and with moderate stirring, which is conducive to the improvement of mass transfer rate and production control.

[0090] (7) The collaborative leaching process does not cause environmental pollution problems due to the discharge of S, SO2, and H2S, and the process flow is simple and clean.

[0091] Example

[0092] The following examples describe the present disclosure in more detail and are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used directly without further processing, and all instruments used in the examples are commercially available.

[0093] Example 1

[0094] Raw materials: acid leaching residue of copper oxide concentrate (containing 3.02% copper) and acid leaching residue of roasted copper sulfide concentrate (containing 5.28% copper) from a copper-cobalt mine in the Democratic Republic of the Congo.

[0095] The mixed slag prepared by acid leaching residue of copper oxide concentrate containing 3.02% copper and acid leaching residue of calcined copper sulfide concentrate containing 5.28% copper in a ratio of 7:3 was added into a stirring tank with a model specification of 3*3.5m at a processing rate of 20t / h. The effective volume of the stirring tank was 21m 3 , add 200g / L sulfuric acid aqueous solution to adjust the mass percentage concentration of the slurry to 17%, send the slurry into the leaching tank, stir and steam to increase the temperature. When the temperature reaches 85℃, keep the leaching tank temperature unchanged and start timing. The leaching time is 4 hours. In the third leaching tank, add hematite powder at a ratio of 5kg / t slag, maintain the temperature at 85℃, and continue leaching for 2 hours.

[0096] After leaching, the mixed liquid was pumped through a discharge pump to the next process for subsequent treatment, such as concentration and filtration. The total copper content in the washed residue after leaching was measured using an atomic absorption spectrometer. The copper grade in the final acid leaching residue was 0.61%. The calculated synergistic leaching rate of copper in the acid leaching residue of copper oxide concentrate and the acid leaching residue of copper sulfide concentrate roasted sand was 88.12%, and the slag rate was 72%.

[0097] Example 2

[0098] Raw materials: acid leaching residue of copper oxide concentrate (containing 2.98% copper) and acid leaching residue of roasted copper sulfide concentrate (containing 6.43% copper) from a copper-cobalt mine in the Democratic Republic of the Congo.

[0099] The mixed slag prepared by acid leaching residue of copper oxide concentrate containing 2.98% copper and acid leaching residue of calcined copper sulfide concentrate containing 6.43% copper in a ratio of 7:3 was added into a stirring tank with a model specification of 3*3.5m at a processing rate of 25t / h. The effective volume of the stirring tank was 21m 3 , add 200g / L sulfuric acid aqueous solution to adjust the mass percentage concentration of the slurry to 17%, send the slurry into the leaching tank, stir and steam to increase the temperature. When the temperature reaches 85℃, keep the leaching tank temperature unchanged and start timing. The leaching time is 4 hours. In the third leaching tank, add hematite powder at a ratio of 5kg / t slag, maintain the temperature at 85℃, and continue leaching for 2 hours.

[0100] After leaching, the mixed liquid was pumped through a discharge pump to the next process for subsequent treatment, such as concentration and filtration. The total copper content in the washed residue after leaching was determined using an atomic absorption spectrometer. The copper grade in the final acid leaching residue was 0.65%. The calculated synergistic leaching rate of copper in the acid leaching residue of copper oxide concentrate and the acid leaching residue of copper sulfide concentrate roasted sand was 88.17%, and the slag rate was 73.1%.

[0101] Example 3

[0102] Raw materials: acid leaching residue of copper oxide concentrate (containing 3.15% copper) and acid leaching residue of roasted copper sulfide concentrate (containing 5.98% copper) from a copper-cobalt mine in the Democratic Republic of the Congo.

[0103] The mixed slag prepared by acid leaching residue of copper oxide concentrate containing 3.15% copper and acid leaching residue of calcined copper sulfide concentrate containing 5.98% copper in a ratio of 7:3 was added into a stirring tank with a model specification of 3*3.5m at a processing rate of 25t / h. The effective volume of the stirring tank was 21m 3 , add 200g / L sulfuric acid aqueous solution to adjust the mass percentage concentration of the slurry to 17%, send the slurry into the leaching tank, stir and steam to increase the temperature. When the temperature reaches 85℃, keep the leaching tank temperature unchanged and start timing. The leaching time is 4 hours. In the third leaching tank, add hematite powder at a ratio of 5kg / t slag, maintain the temperature at 85℃, and continue leaching for 2 hours.

[0104] After leaching, the mixed liquid was pumped through a discharge pump to the next process for subsequent treatment, such as concentration and filtration. The total copper content in the washed residue after leaching was determined using an atomic absorption spectrometer. The copper grade in the final acid leaching residue was 0.66%. The calculated synergistic leaching rate of copper in the acid leaching residue of copper oxide concentrate and the acid leaching residue of copper sulfide concentrate roasted sand was 88.25%, and the slag rate was 71.2%.

[0105] Example 4

[0106] Raw materials: acid leaching residue of copper oxide concentrate (containing 2.99% copper) and acid leaching residue of roasted copper sulfide concentrate (containing 7.59% copper) from a copper-cobalt mine in the Democratic Republic of the Congo.

[0107] The mixed slag prepared by acid leaching residue of copper oxide concentrate containing 2.99% copper and acid leaching residue of calcined copper sulfide concentrate containing 7.59% copper in a ratio of 7:3 was added into a stirring tank with a model specification of 3*3.5m at a processing rate of 25t / h. The effective volume of the stirring tank was 21m 3 , add 200g / L sulfuric acid aqueous solution to adjust the mass percentage concentration of the slurry to 17%, send the slurry into the leaching tank, stir and steam to increase the temperature. When the temperature reaches 85℃, keep the leaching tank temperature unchanged and start timing. The leaching time is 4 hours. In the third leaching tank, add hematite powder at a ratio of 5kg / t slag, maintain the temperature at 85℃, and continue leaching for 2 hours.

[0108] After leaching, the mixed liquid was pumped through a discharge pump to the next process for subsequent treatment, such as concentration and filtration. The total copper content in the washed residue after leaching was measured using an atomic absorption spectrometer. The copper grade in the final acid leaching residue was 0.69%. The calculated synergistic leaching rate of copper in the acid leaching residue of copper oxide concentrate and the acid leaching residue of copper sulfide concentrate roasted sand was 88.24%, and the slag rate was 74.5%.

[0109] Example 5

[0110] Raw materials: acid leaching residue of copper oxide concentrate (containing 2.8% copper) and acid leaching residue of roasted copper sulfide concentrate (containing 6.8% copper) from a copper-cobalt mine in the Democratic Republic of the Congo.

[0111] Multiple groups of leaching experiments were carried out in sequence using the above-mentioned copper sulfide concentrate roasted acid leaching residue and copper oxide concentrate acid leaching residue in a mass ratio of 10:0 to 0:10 as described in Table 1; the remaining experimental parameters are shown in Table 1, the experimental steps are the same as in Example 1, and the leaching results are shown in Table 1.

[0112] Table 1 Multiple groups of leaching experimental conditions and experimental results of Example 5

[0113]

[0114] As shown in Table 1, the leaching rates of the copper sulfide concentrate roasted acid leaching residue (10:0) or the copper oxide concentrate acid leaching residue (0:10) alone were lower than those of the two in the collaborative leaching. In the collaborative leaching, the leaching rates of the experiments with the mass ratios of copper sulfide concentrate roasted acid leaching residue to copper oxide concentrate acid leaching residue of 4:6 and 3:7 were the highest (both reaching over 88%).

[0115] Comparative Example 1

[0116] Raw materials: acid leaching residue of copper oxide concentrate (containing 3% copper) and acid leaching residue of roasted copper sulfide concentrate (containing 6.3% copper) from a copper-cobalt mine in the Democratic Republic of the Congo.

[0117] Multiple groups of leaching experiments were carried out using the above-mentioned copper sulfide concentrate roasted acid leaching residue and copper oxide concentrate acid leaching residue in a mass ratio of 10:0 to 0:10 as shown in Table 2; the remaining experimental parameters are shown in Table 2. Oxidative leaching was not included in the experiment. The other steps were the same as in Example 1. The leaching results are shown in Table 2.

[0118] Table 2 Multiple groups of leaching experimental conditions and experimental results of comparative example 1

[0119]

[0120]

[0121] As shown in Table 2, in the experiment without the oxidative leaching step, the leaching rates of the mass ratios of 4:6 and 3:7 were the highest (the leaching rate was only about 83%). However, regardless of how the raw material ratios were changed, the leaching rate of the comparative example 1 group that did not include oxidative leaching was lower than that of the example group.

[0122] The present invention discloses a method for the synergistic, step-by-step leaching of copper metal using strong oxidation from copper oxide concentrate acid leaching residue and copper sulfide concentrate roasted acid leaching residue. The method comprises the following steps: using copper oxide concentrate acid leaching residue and copper sulfide concentrate roasted acid leaching residue as raw materials, first mixing copper oxide concentrate acid leaching residue with a grade of 2-4% and copper sulfide concentrate roasted acid leaching residue with a grade of 4-8% in a certain proportion, then slurrying using sulfuric acid and raffinate as leaching agents, maintaining a certain acidity, and performing steam-heated synergistic leaching for a certain period of time. Thereafter, a solid strong oxidant is added while maintaining a constant temperature and continuing leaching for a further period of time. The leachate is then subjected to extraction and electrowinning processes, effectively recovering copper metal from the copper oxide concentrate acid leaching residue and the copper sulfide concentrate roasted acid leaching residue, both of which are relatively difficult to leach normally. This step-by-step synergistic-oxidation leaching process is highly applicable to copper oxide concentrate acid leaching residue and copper sulfide concentrate roasted acid leaching residue with complex mineral compositions. No pretreatment of the raw materials is required, and the synergistic leaching rate reaches over 88%. The method has the advantages of high recovery rate, simple process, low cost, low investment, environmental protection and high efficiency. It effectively recovers Cu metal in difficult-to-treat leaching tailings, avoids waste of resources and reduces the environmental management cost of acid leaching residue discharge.

[0123] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions within the scope of the claims.

Claims

1. A method for leaching copper metal by using acid leaching residues from copper oxide concentrate and acid leaching residues from roasted copper sulfide concentrate, characterized in that: The Cu grade of the acid leaching residue of the copper oxide concentrate is 2-4%, and the Cu grade of the acid leaching residue of the calcined copper sulfide concentrate is 4-8%; A copper oxide concentrate with a copper grade of 15-25% is obtained by flotation of a copper-cobalt mixed ore with a grade of 2-4% through a process of first flotation of copper sulfide and then flotation of copper oxide. The copper oxide concentrate is subjected to a sulfuric acid leaching process to obtain the copper oxide concentrate acid leaching residue; A copper sulfide concentrate with a copper grade of 60-70% is obtained by flotation of a copper-cobalt mixed ore with a grade of 2-4% through a process of first flotation of copper sulfide and then flotation of copper oxide. The copper sulfide concentrate is subjected to oxidation roasting and partial acid roasting to obtain roasted sand with a grade of 50-60%. The roasted sand is subjected to a sulfuric acid leaching process to obtain the copper sulfide concentrate roasted sand acid leaching residue. The method comprises the following steps: (1) mixing the acid leaching residue of copper oxide concentrate and the acid leaching residue of copper sulfide concentrate roasted sand in a mass ratio of (7-6):(3-4) to obtain a mixed slag material; (2) stirring and mixing the obtained mixed slag material with a leaching agent to obtain a slurry, wherein the leaching agent is a sulfuric acid solution system leaching agent; the mass concentration of the obtained slurry is 15-17%; (3) heating and leaching the obtained slurry, wherein the leaching temperature is 80-90° C.; (4) After the heating leaching is completed, an oxidant is added to perform oxidative leaching to obtain a leached slurry; (5) performing solid-liquid separation on the obtained leaching slurry to obtain leaching residue and leachate; (6) washing the obtained leaching residue to obtain washing residue and washing liquid; extracting the obtained leaching liquid to obtain a loaded organic phase and a raffinate, wherein the obtained washing liquid is used in the extraction step, and the obtained washing residue is discharged for tail treatment; the raffinate obtained by the extraction is used to prepare the sulfuric acid solution system leaching agent; (7) The obtained loaded organic phase is subjected to back extraction and electrolysis to obtain metallic copper.

2. The method for leaching copper metal by using acid leaching residues of copper oxide concentrate and acid leaching residues of roasted copper sulfide concentrate according to claim 1, characterized in that: In step (3), the initial concentration of the leaching agent in the slurry is 180-220 g / L.

3. The method for leaching copper metal by using acid leaching residues of copper oxide concentrate and acid leaching residues of roasted copper sulfide concentrate according to claim 1, characterized in that: The leaching time of the heated leaching in step (3) is 4-6 hours.

4. The method for leaching copper metal by using acid leaching residues of copper oxide concentrate and acid leaching residues of roasted copper sulfide concentrate according to claim 1, characterized in that: The leaching rate of the heated leaching in step (3) is not less than 80%.

5. The method for leaching copper metal by cooperating acid leaching residues of copper oxide concentrate and acid leaching residues of copper sulfide concentrate roasted sand according to claim 1, characterized in that: The leaching time of the oxidation leaching in step (4) is 2-3 hours.

6. The method for leaching copper metal by cooperating acid leaching residues of copper oxide concentrate and acid leaching residues of copper sulfide concentrate roasted sand according to claim 1, characterized in that: The leaching rate of the oxidative leaching in step (4) is not less than 88%.

7. The method for leaching copper metal by using acid leaching residues of copper oxide concentrate and acid leaching residues of roasted copper sulfide concentrate according to claim 1, characterized in that: The oxidant added in step (4) includes hematite or magnetite.

8. The method for leaching copper metal by using acid leaching residues from copper oxide concentrate and acid leaching residues from roasted copper sulfide concentrate according to claim 7, characterized in that: The amount of hematite added relative to the mixed slag is 4-8 kg / t.

9. The method for leaching copper metal by using acid leaching residues from copper oxide concentrate and acid leaching residues from roasted copper sulfide concentrate according to claim 1, characterized in that: The solid-liquid separation in step (5) also includes concentrating the leached slurry.

10. The method for leaching copper metal by using acid leaching residues from copper oxide concentrate and acid leaching residues from roasted copper sulfide concentrate according to claim 1, characterized in that: The washing of the obtained leaching residue in step (6) comprises stirring and washing the obtained leaching residue with clean water having a pH of 6.5-7.5 under natural conditions.

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