A process for the extraction of valuable metals from copper-cobalt containing polymetallic alloys

Abstract

This invention relates to a method for extracting valuable metals from a copper-cobalt multimetallic alloy, comprising the following steps: (1) melting the copper-cobalt multimetallic alloy to form an alloy melt; (2) adding a phosphorus-containing material to the alloy melt; simultaneously adding at least one of a silicon-containing material and a carbon-containing material, maintaining the temperature uniformly for a certain period of time, removing the slag, and obtaining a phosphorus alloy melt; (3) atomizing the phosphorus alloy melt obtained in step (2) to obtain phosphorus alloy powder; (4) oxidizing and acid-leaching the phosphorus alloy powder obtained in step (3) with sulfuric acid, during which oxygen-containing gas is introduced. The direct acid leaching process for cobalt and copper provided by this invention does not require pressurization or the addition of chlorine, chloride ions, and related catalysts, avoiding the introduction of other impurities and toxic and harmful elements into the system, reducing the difficulty of subsequent cobalt and copper separation and purification, and the equipment is easy to implement. The comprehensive economic and environmental advantages of the process are very significant.

Description

Technical Field

[0001] This invention belongs to the field of metallurgy, and in particular relates to a method for extracting valuable metals from copper-cobalt polymetallic alloys. Background Technology

[0002] The smelting process of cobalt and nickel generally begins by obtaining nickel- and cobalt-containing alloy intermediates, which are then used as raw materials for further separation and purification to obtain nickel and cobalt compounds. For example, copper-cobalt ore smelting first yields copper-cobalt white alloy intermediates, while the reduction smelting of waste lithium-ion batteries yields iron-cobalt-nickel-copper alloys. These alloy intermediates mainly contain Cu 5-40%, Co 10-45%, Fe 25-75%, Ni 0-40%, Cr 0-20%, and Mn 0-40%. In addition, they contain small amounts of Si and other impurities, sometimes with Si content reaching up to 15%. The main constituent phases of these alloys—iron-cobalt alloys, copper alloys, and silicon-solution iron-cobalt-copper alloys—are all corrosion-resistant alloy phases with poor acid leaching performance. In particular, high-silicon white alloys suffer from low leaching rates and slow leaching speeds in atmospheric pressure acid leaching processes, which has always constrained their smelting and processing.

[0003] Currently, high-pressure leaching processes are commonly used in industry, including high-pressure oxidation acid leaching (such as the Chambishi Cobalt Plant in Zambia) and atmospheric pressure pre-leaching-pressurized oxidation acid leaching combined leaching processes (such as Jinchuan Group). However, pressurized leaching equipment requires large investments, has high operational requirements, and poses significant safety risks, which greatly limits its application and promotion. Therefore, people have been committed to researching and developing atmospheric pressure acid leaching processes for copper-cobalt multimetallic alloys.

[0004] To effectively increase the leaching rate under normal pressure, many enhanced leaching methods have been proposed, including pre-desiliconization activation, mechanical activation, chloride ion enhancement, fluoride ion enhancement, and electrochemical activation. Specifically, patent 201110309215.8, "A Method for Desiliconizing Cobalt White Alloy," jointly developed by the Beijing General Research Institute of Mining and Metallurgy and Jiangsu Kailike Cobalt Industry Co., Ltd., targets high-silicon cobalt white alloys. It employs a method of adding a desiliconizing agent and a slagging agent during the alloy's molten state for desiliconization and slagging smelting. Then, the melt is atomized into powder, followed by oxidative acid leaching of the alloy powder. The desiliconizing agent is selected from one or more combinations of cobalt oxide, iron oxide, copper oxide, and lithium cobalt oxide oxidants, while the slagging agent is selected from one or two combinations of calcium oxide and magnesium oxide. The desiliconizing agent reacts with metallic silicon in the alloy to convert it into silicon dioxide, and then reacts with the slagging agent to form slag, thereby achieving silicon removal. However, the acid leaching of the alloy powder still requires the use of strong oxidants such as sodium chlorate and chloride ions to achieve the desired leaching effect. Another Chinese patent, 201510505985.8, discloses a method for leaching valuable metals from cobalt-copper white alloy. The method involves first melting the copper-cobalt white alloy, controlling the furnace temperature to be greater than 1400℃, then adding a slag-forming agent containing gas and manganese materials to form MnO-SiO2 slag for blowing, desiliconization, and tempering. This process removes Si from the alloy using MnO-SiO2 slag and obtains Fe-Co-Cu alloy powder. Copper and cobalt are then separated and recovered using a hydrometallurgical method. However, this method is problematic because Co is easily oxidized together with Mn and Fe, which can lead to a large amount of valuable metals being carried in the slag, resulting in significant losses of valuable metals. Therefore, the control conditions for slag-forming operations are extremely important.

[0005] Patent application 201510055126.3 from Ganzhou Yihao Youmei Technology Co., Ltd., entitled "A Mechanically Activated and Strengthened Cobalt White Alloy Immersion Process," discloses a process that uses a fluidized bed air jet mill to finely grind and activate cobalt white alloy for leaching. Using this process, the Co and Cu leaching rates reach over 96%. However, mechanical activation employs dry grinding and requires the addition of reducing agents and surfactants, and it cannot solve the problem of difficult solid-liquid separation of the leaching solution due to high silicon content.

[0006] Foshan Bangpu Recycling Technology Co., Ltd.'s invention patent 200810219451.9, "A Method for Recovering Valuable Metals from Cobalt White Alloy," involves finely grinding the white alloy and leaching it with a chlorine + sulfuric acid system, achieving a cobalt, copper, and iron leaching rate of over 99.5%. Jinchuan Group Co., Ltd.'s invention patent application 201410179598.5, "A Continuous Chlorination Leaching Method for White Alloy," uses chlorine as an oxidant in a 60-80 g / L hydrochloric acid solution for 8 hours, achieving a cobalt and copper leaching rate of over 99%. However, chlorine is a highly toxic gas, posing a significant risk and exhibiting strong corrosiveness, thus requiring high-quality equipment materials.

[0007] Existing technologies generally address the difficulty in leaching iron-cobalt-nickel-copper alloys by altering the external environment of alloy leaching, such as smelting to produce calcium (magnesium) silicon slag or manganese slag for desiliconization, fine grinding of alloy powder, and changing the leaching agent system and oxidant. However, these technologies have certain limitations, limited application effects, high difficulty in industrial implementation, and poor economic efficiency. Summary of the Invention

[0008] To overcome the shortcomings of existing technologies, and considering the inherent difficulty in leaching copper-cobalt multimetallic alloys due to their corrosion resistance, this invention proposes a method for rapidly leaching valuable metals from these alloys by effectively altering their internal structure with additives, thereby increasing their acid corrosion resistance. This process is not only simple to operate but also environmentally friendly and efficient. The specific scheme is as follows:

[0009] A method for extracting valuable metals from copper-cobalt multimetallic alloys includes the following steps:

[0010] (1) Melt a copper-cobalt multimetallic alloy to form an alloy melt;

[0011] (2) Add phosphorus-containing material to the alloy melt; at the same time add at least one of silicon-containing material and carbon-containing material, the amount of phosphorus-containing material added is 0.05-0.8 times the mass of the copper-cobalt multimetallic alloy, the amount of silicon-containing material added is 0-0.5 times the mass of the copper-cobalt multimetallic alloy, and the amount of carbon-containing material added is 0-0.3 times the mass of the copper-cobalt multimetallic alloy. Keep it at a uniform temperature for a certain period of time, remove the slag, and obtain the phosphorus alloy melt;

[0012] (3) The phosphorus alloy melt obtained in step (2) is atomized to form phosphorus alloy powder;

[0013] (4) The phosphorus alloy powder obtained in step (3) is oxidized and acid-leached with sulfuric acid. The amount of sulfuric acid used is more than 0.5 times the theoretical amount of copper, cobalt and nickel leaching. The reaction temperature is ≥50℃. Oxygen-containing gas is introduced during the acid leaching process.

[0014] Preferably, in step (1), the copper-cobalt multimetallic alloy is melted in an electric furnace or a converter.

[0015] In addition, in order to increase the economic benefits of the process, the copper-cobalt metal alloy in step (1) includes not only the alloys described in the background art, but also other waste alloys containing cobalt and copper, such as waste high-temperature alloys.

[0016] More preferably, an electric furnace is used for melting. The electric furnace includes one or more of the following: induction furnace, electric arc furnace, resistance furnace, plasma furnace, and electron beam furnace.

[0017] Preferably, the phosphorus-containing material is one or more of the following: phosphorus bronze, phosphorus-containing pig iron, phosphorus-containing cast iron, yellow phosphorus, red phosphorus, phosphorus pentoxide, apatite, hydroxyapatite, fluorapatite, calcium phosphate, ferric phosphate, nickel phosphate, calcium pyrophosphate, dicalcium phosphate, calcium dihydrogen phosphate, calcium fluorophosphate, phosphate concentrate, calcium magnesium phosphate fertilizer, superphosphate, struvite, ferric phosphorus, and ferric phosphate. During the conversion of the added phosphorus-containing material into scum, it can, on the one hand, provide phosphorus (P) to the alloy melt; on the other hand, the formed scum can prevent the alloy melt from being oxidized and lost in large quantities at high temperatures.

[0018] Preferably, the silicon-containing material is one or more of river sand, silica, and quartz.

[0019] Preferably, the carbon-containing material is one or more of coke, pulverized coal, coal, petroleum coke, granular coal, and anthracite.

[0020] Preferably, in step (2), the mass ratio of CaO / SiO2 in the scum is 0.5-1.3.

[0021] More preferably, in step (2), the mass ratio of CaO / SiO2 in the scum is 0.55-1.20.

[0022] Preferably, in step (3), the mass fraction of P in the phosphorus alloy powder is ≥3%, and the particle size is ≤150 micrometers. In this invention, after converting the low-phosphorus (P content ≤2.5%) copper-cobalt multimetallic alloy into a high-P alloy, the water-atomized alloy powder, on the one hand, because P is enriched in the intergranular space, not only effectively inhibits the growth of the corrosion-resistant alloy phase, but also the fragile intergranular space becomes an active site for acid leaching; on the other hand, during the oxidation and rust leaching process of the alloy powder, P is insoluble in sulfuric acid and directly enters the iron slag. This indicates that the high-concentration sulfuric acid diffused into the intergranular space can directly contact the copper-cobalt multimetallic alloy phase, effectively expanding the reaction area and thus increasing the acid leaching rate.

[0023] More preferably, in step (3), the mass fraction of P in the phosphorus alloy powder is ≥6%.

[0024] Preferably, in step (2), the heat preservation time is ≥15 min.

[0025] Preferably, in step (2), one or more of the following gases are introduced during the reaction: air, oxygen, argon, and nitrogen, and the mixture is stirred.

[0026] Preferably, in step (4), the amount of sulfuric acid used is more than 0.5 times the theoretical amount used for leaching copper, cobalt, and nickel, and the reaction temperature is ≥50℃. Because the alloy powder mentioned in step (3) has a high P content, it is easy to leach directly with sulfuric acid. Therefore, the oxidation and corrosion leaching process does not require the addition of Cl--containing reinforcing agents (such as sodium chloride, ammonium chloride, etc.).

[0027] The theoretical amount of sulfuric acid used is calculated according to the following equation:

[0028] Cu + H₂SO₄ = CuSO₄ + H₂O

[0029] Co + H₂SO₄ = CoSO₄ + H₂O

[0030] Ni + H₂SO₄ = CoSO₄ + H₂O

[0031] More preferably, in step (4), the amount of sulfuric acid used is more than 0.8 times the theoretical amount used for leaching copper, cobalt, and nickel, and the acid leaching temperature is ≥70℃.

[0032] In a further preferred embodiment, in step (4), the amount of sulfuric acid used is 1.05 to 2.5 times the theoretical amount used for leaching copper, cobalt, and nickel, and the leaching temperature is greater than 50°C. At this time, the leaching rate of copper and cobalt is higher than 98%. The iron in the alloy exists in the leaching residue in the form of iron oxide or goethite, and the Fe content (dry weight) in the leaching residue is greater than 40%. In addition, the added P element is also enriched in the slag phase. This step achieves the purpose of effectively leaching copper and cobalt, while also removing impurity iron and added impurity P, reducing the workload of removing iron and phosphorus in the next step of wet separation and recovery of valuable metals. It is worth noting that the aforementioned treatment steps of the copper-cobalt polymetallic alloy greatly improve the leaching performance of the alloy powder, thereby avoiding the operation of adding catalysts such as ammonium sulfate in the early technology of rust oxidation leaching process, avoiding the introduction of other impurity elements / ions, and significantly reducing the difficulty of subsequent purification of cobalt, copper, and nickel.

[0033] Preferably, in step (4), the oxygen-containing gas is one or more of air, pure oxygen, and a mixture of carrier gas and oxygen; the carrier gas is one or more of nitrogen, inert gas, or carbon dioxide.

[0034] Compared with the prior art, the advantages of the present invention are:

[0035] (1) Based on the inventor's latest research results: the corrosion resistance of high-phosphorus copper-cobalt polymetallic alloys is worse than that of phosphorus-free copper-cobalt polymetallic alloys. By adding phosphorus-containing materials, the internal structural characteristics of copper-cobalt polymetallic alloys are effectively changed, and their acid etching performance is improved, thereby realizing the rapid leaching of copper-cobalt polymetallic alloys. Therefore, the process is more economical.

[0036] (2) The method for extracting valuable metals from copper-cobalt polymetallic alloys described in this invention provides sufficient phosphorus to the alloy melt by adding phosphorus-containing materials, silicon-containing materials and / or carbon-containing materials to the alloy melt. The resulting slag can not only absorb impurities in the alloy, but also avoid the oxidation loss of valuable metals in the alloy melt.

[0037] (3) The rust oxidation leaching process for cobalt and copper provided by this invention does not require the addition of any catalysts, thus avoiding the introduction of other impurities and toxic or harmful elements into the system. This reduces the difficulty of subsequent cobalt and copper separation and purification, and the equipment is easy to implement. The overall economic and environmental advantages of the process are very significant. The direct acid leaching process for cobalt and copper provided by this invention does not require pressurization or the addition of chlorine, chloride ions, or related catalysts, thus avoiding the introduction of other impurities and toxic or harmful elements into the system. This reduces the difficulty of subsequent cobalt and copper separation and purification, and the equipment is easy to implement. The overall economic and environmental advantages of the process are very significant. Detailed Implementation

[0038] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments in the specification, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0039] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0040] Unless otherwise specified, all reagents and raw materials used in this invention are commercially available products or products that can be prepared by known methods.

[0041] Example 1:

[0042] A method for extracting valuable metals from copper-cobalt multimetallic alloys includes the following steps:

[0043] (1) The copper-cobalt polymetallic alloy is a copper-cobalt white alloy (the main components have mass contents of Co 38.87%, Fe 32.45%, Cu 13.45%, and Si 10.15%), which is a product of copper-cobalt ore smelting. The copper-cobalt white alloy is placed in an electric furnace to melt and form an alloy melt.

[0044] (2) Add apatite (0.08 times the mass of the alloy) and granular coal (0.10 times the mass of the alloy) to the above alloy melt, keep it at 1600℃ for 30 minutes and then remove the slag, wherein the CaO / SiO2 ratio of the slag is 1.2.

[0045] (3) The melt described in step (2) is atomized into powder by water atomization, characterized in that the mass fraction of P in the alloy powder is 3.5% and the particle size of the alloy powder is ≤150μm.

[0046] (4) The alloy powder from step (3) was leached by sulfuric acid oxidation. Oxygen was used as the oxidant. The amount of sulfuric acid used was 1.7 times the theoretical amount required to leach out all cobalt and copper. The leaching temperature was 75℃ and the leaching time was 2.0h. The leaching rates of copper and cobalt were 98.35% and 99.57%, respectively. The mass fraction of Fe in the iron oxide slag (dry weight) was 47.81%, and the P content in the slag was 4.6%.

[0047] Example 2:

[0048] A method for extracting valuable metals from copper-cobalt multimetallic alloys includes the following steps:

[0049] (1) The copper-cobalt polymetallic alloy is a product of waste lithium-ion battery reduction smelting (the main components have mass fractions of Co 10.63%, Ni 7.71%, Cu 29.57%, Fe 35.16%, Mn 13.24%, and Cr 2.01%). The alloy is placed in a converter for melting to form an alloy melt.

[0050] (2) Fluoroapatite and phosphorus pentoxide (in a mass ratio of 1:1, with a total addition amount of 0.13 times the alloy mass), silica (in an amount of 0.1 times the alloy mass), and coke powder (in an amount of 0.15 times the alloy mass) are added to the above alloy melt. After melting at 1550℃ for 30 minutes, the slag is removed, wherein the slag CaO / SiO2 = 1.0.

[0051] (3) The melt described in step (2) is atomized into granules by water atomization, characterized in that the mass fraction of P in the alloy particles is 5.5% and the particle size of the alloy powder is ≤150μm.

[0052] (4) The alloy particles from step (3) are first finely ground into powder, and then leached by sulfuric acid oxidation. The oxidant is a mixture of pure oxygen and air. The amount of sulfuric acid used is 1.4 times the theoretical amount required to leach out all cobalt, copper and nickel. The leaching temperature is 90℃ and the leaching time is 1.5h. The leaching rates of copper, cobalt and nickel are 98.32%, 99.29% and 99.10% respectively. The mass fraction of Fe in the iron oxide slag (dry weight) is 52.80% and the P content in the slag is 8.9%.

[0053] Example 3:

[0054] A method for extracting valuable metals from copper-cobalt multimetallic alloys includes the following steps:

[0055] (1) The copper-cobalt polymetallic alloy contained is a copper-cobalt white alloy (Co 33.83%, Fe 37.10%, Cu 16.88%, Ni 3.5%, Si 5%). The alloy is placed in a converter to melt and form an alloy melt.

[0056] (2) Add phosphorus-containing materials (calcium dihydrogen phosphate, calcium fluorophosphate, and fluorapatite in a mass ratio of 1:1:1, with a total addition amount of 0.4 times the alloy mass), river sand (0.25 times the alloy mass), and coke powder (0.25 times the alloy mass) to the above alloy melt. Maintain the melt at 1570℃ for 40 minutes, and introduce nitrogen gas to stir the molten pool during the melting process. Remove the slag, where the CaO / SiO2 ratio of the slag is 0.85.

[0057] (3) The melt water atomization powder described in step (2) is characterized in that the mass fraction of P in the alloy particles is 10%.

[0058] (4) The alloy powder described in step (3) was leached by sulfuric acid corrosion oxidation. Air was used as the oxidant. The amount of sulfuric acid was 1.1 times the theoretical amount required to leach out all cobalt, copper and nickel. The leaching temperature was 55℃ and the leaching time was 6.0h. The leaching rates of copper, cobalt and nickel were 98.03%, 99.42% and 99.37% respectively. The mass fraction of Fe in the iron oxide slag (dry weight) was 55.53% and the P content in the slag was 14.5%.

[0059] Comparative Example 1:

[0060] This comparative example is used to compare with Example 3. The raw materials are the same as those in Example 3. After the copper-cobalt white alloy is melted into an alloy melt, no phosphorus-containing materials, silicon-containing materials, or carbon-containing materials are added. The alloy powder is directly atomized into powder with water. The particle size of the alloy powder is ≤150μm, and the mass fraction of P in the alloy particles is 0.25%. The remaining steps and processes are the same as those in Example 3. When the leaching time is the same (6.0h), the leaching rates of copper, cobalt, and nickel are only 74.79%, 88.15%, and 89.61%, respectively, which are far lower than the leaching rates of Example 3.

Claims

1. A process for the extraction of valuable metals from a copper-cobalt containing polymetallic alloy, characterized in that, Includes the following steps: (1) Melt a copper-cobalt multimetallic alloy to form an alloy melt; (2) Add phosphorus-containing material to the alloy melt; at the same time add at least one of silicon-containing material and carbon-containing material, wherein the amount of phosphorus-containing material added is 0.05-0.8 times the mass of the copper-cobalt multimetallic alloy, the amount of silicon-containing material added is 0-0.5 times the mass of the copper-cobalt multimetallic alloy, and the amount of carbon-containing material added is 0-0.3 times the mass of the copper-cobalt multimetallic alloy. Keep it at the temperature for a period of time, remove the slag, and obtain the phosphorus alloy melt; The phosphorus-containing material is one or more of the following: phosphorus bronze, phosphorus-containing pig iron, phosphorus-containing cast iron, yellow phosphorus, red phosphorus, phosphorus pentoxide, apatite, calcium phosphate, ferric phosphate, nickel phosphate, calcium pyrophosphate, dicalcium phosphate, calcium dihydrogen phosphate, calcium fluorophosphate, phosphate concentrate, calcium magnesium phosphate fertilizer, superphosphate, struvite, ferric phosphate, and ferric phosphate; the silicon-containing material is one or more of the following: river sand, silica, and quartz; the carbon-containing material is one or more of the following: coke, coal, and petroleum coke; the CaO / SiO2 mass ratio in the slag is 0.5-1.3; (3) The phosphorus alloy melt obtained in step (2) is atomized to obtain phosphorus alloy powder; the mass fraction of P in the phosphorus alloy powder is ≥3% and the particle size is ≤150 micrometers; (4) The phosphorus alloy powder obtained in step (3) is oxidized and acid-leached with sulfuric acid, and oxygen-containing gas is introduced during the acid leaching process.

2. The process for the extraction of valuable metals from copper-cobalt containing polymetallic alloys according to claim 1, characterized in that: In step (1), the copper-cobalt multimetallic alloy is melted using an electric furnace or a converter.

3. The method of extracting valuable metals from copper-cobalt containing polymetallic alloys according to claim 1, characterized in that: In step (2), the heat preservation time is ≥15min.

4. The method of extracting valuable metals from copper-cobalt containing polymetallic alloys according to claim 1, characterized in that: In step (2), one or more of the following gases are introduced during the reaction: air, oxygen, argon, and nitrogen, and the mixture is stirred.

5. The method for extracting valuable metals from copper-cobalt-containing polymetallic alloys according to claim 1, characterized in that: In step (4), the amount of sulfuric acid used is more than 0.5 times the theoretical amount used for copper, cobalt and nickel leaching, and the reaction temperature is ≥50℃.

6. The method for extracting valuable metals from copper-cobalt-containing polymetallic alloys according to claim 1, characterized in that: In step (4), the amount of sulfuric acid used is more than 0.8 times the theoretical amount used for leaching copper, cobalt, and nickel, and the acid leaching temperature is ≥70℃.

7. The method for extracting valuable metals from copper-cobalt-containing polymetallic alloys according to claim 1, characterized in that: In step (4), the oxygen-containing gas is one or more of air, pure oxygen, and a mixture of carrier gas and oxygen; the carrier gas is one or more of nitrogen, inert gas, or carbon dioxide.

8. The method for extracting valuable metals from copper-cobalt-containing polymetallic alloys according to claim 1, characterized in that: In step (2), the coal is one or more of pulverized coal, granular coal, and anthracite.