A process for leaching valuable metals from iron-cobalt-copper-nickel containing alloys

Abstract

The present application relates to a kind of methods for leaching valuable metals from iron-containing cobalt copper nickel alloy, comprising the following steps: (1) the iron-containing cobalt copper nickel alloy is melted, and alloy melt is formed;(2) phosphorus-containing material is added to the alloy melt, and homogeneous is kept for a period of time, and phosphorus alloy melt is obtained;The mass of phosphorus-containing material added is 0.03 times-0.5 times the mass of iron-containing cobalt copper nickel alloy;(3) the phosphorus alloy melt of step (2) is atomized and powdered, and phosphorus alloy powder is obtained, the mass fraction of P in phosphorus alloy powder is ≥3%, and particle size is ≤150 microns;(4) the phosphorus alloy powder of step (3) is oxidized and acid leached with sulfuric acid;During the leaching process, oxygen-containing gas is introduced.The leaching procedure provided by the present application for directly acid leaching cobalt and copper does not need to be pressurized or add chlorine, chloride ion and related catalysts, the equipment is easy to realize, and the comprehensive economic and environmental advantages of the process are very significant.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, specifically to a method for leaching valuable metals from an iron-cobalt-copper-nickel alloy. 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 iron, cobalt, copper, and nickel.

[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. This method involves first melting the copper-cobalt white alloy, controlling the furnace temperature above 1400℃, then adding a slag-forming agent containing gas and manganese materials to create MnO-SiO2 slag for blowing, desiliconization, and tempering. This removes Si from the alloy as MnO-SiO2 slag, yielding Fe-Co-Cu alloy powder. Copper and cobalt are then separated and recovered using hydrometallurgical methods. However, this method suffers from significant losses because Co easily oxidizes with Mn and Fe, leading to the inclusion of large amounts of valuable metals in the slag. Therefore, it requires very strict control of the slag-forming process. Ganzhou Yihao Youmei Technology Co., Ltd.'s patent application, 201510055126.3, "A Mechanically Activated and Strengthened Cobalt White Alloy Leaching Process," discloses a process using a fluidized bed air jet mill to finely grind and activate the cobalt white alloy for leaching. Using this process, the Co and Cu leaching rates reach over 96%. However, mechanical activation uses dry grinding and requires the addition of reducing agents and surfactants, and it cannot solve the problem of difficult solid-liquid separation of the leachate caused by high silicon content.

[0005] 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.

[0006] 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 / 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

[0007] To overcome the shortcomings of existing technologies, and considering the inherent difficulty in leaching corrosion in iron-cobalt-copper-nickel alloys, 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:

[0008] A method for leaching valuable metals from an iron-cobalt-copper-nickel alloy includes the following steps:

[0009] (1) Melt the iron-cobalt-copper-nickel alloy to form an alloy melt;

[0010] (2) Add phosphorus-containing material to the alloy melt and keep it at a temperature for a period of time to obtain phosphorus alloy melt; the mass of the added phosphorus-containing material is 0.03-0.5 times the mass of the iron-cobalt-copper-nickel alloy.

[0011] (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.

[0012] (4) The phosphorus alloy powder obtained in step (3) is oxidized and acid-leached with sulfuric acid; oxygen-containing gas is introduced during the leaching process.

[0013] Based on the inventors' latest research findings, after converting the low-phosphorus (P content ≤ 2.5%) Fe-Co-Cu-Ni alloy into a high-P content Fe-Co-Ni-Cu-P alloy, the water-atomized alloy powder exhibits several advantages. Firstly, because P is enriched in the intergranular spaces, it not only effectively inhibits the growth of the corrosion-resistant alloy phase, but the fragile intergranular spaces also become active sites for acid leaching. Secondly, during the oxidative corrosion 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 spaces can directly contact the Fe-Co-Ni-Cu phase, effectively expanding the reaction area and thus increasing the acid leaching rate.

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

[0015] More preferably, in step (1), 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.

[0016] In addition, in order to increase the economic benefits of the process, the iron-cobalt-copper-nickel alloy in step (1) includes not only the alloys described in the background art, but also other waste alloys containing nickel, cobalt and copper, such as waste high-temperature alloys, waste iron-nickel stainless steel, etc.

[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, iron phosphate, nickel phosphate, calcium pyrophosphate, calcium hydrogen phosphate, calcium dihydrogen phosphate, calcium fluorophosphate, phosphate concentrate, calcium magnesium phosphate fertilizer, superphosphate, struvite, ferric phosphorus, and iron phosphate.

[0018] Preferably, in step (3), the mass fraction of P in the phosphorus alloy powder is ≥3% and the particle size is ≤150 micrometers.

[0019] More preferably, in step (3), the mass fraction of P in the phosphorus alloy powder is ≥6%.

[0020] Preferably, the heat preservation time in step (2) is ≥15 min.

[0021] Preferably, in step (2), one or more of the following gases—air, oxygen, argon, and nitrogen—are introduced during the reaction for stirring. This ensures that P is fully mixed within the alloy melt.

[0022] Preferably, the oxygen-containing gas in step (4) 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.

[0023] 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 acid leaching 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.).

[0024] The theoretical amount of sulfuric acid used is calculated according to the following equation:

[0025] Cu + H₂SO₄ = CuSO₄ + H₂O

[0026] Co + H₂SO₄ = CoSO₄ + H₂O

[0027] Ni + H₂SO₄ = CoSO₄ + H₂O

[0028] In a further preferred embodiment, 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℃.

[0029] Further preferably, 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, the leaching temperature is greater than 50°C, and the leaching rate of copper, cobalt, and nickel 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, cobalt, and nickel, while also removing impurities such as iron and added impurities such as P, reducing the workload of iron and phosphorus removal in the next step of wet separation and recovery of valuable metals. It is worth noting that the aforementioned treatment steps of the iron-cobalt-copper-nickel 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 and copper.

[0030] Compared with the prior art, the advantages of the present invention are:

[0031] (1) Based on the inventor's latest research results: the corrosion resistance of Fe-Co-Ni-Cu-P alloy is significantly lower than that of Fe-Co-Ni-Cu alloy. By adding phosphorus-containing materials, the internal structural characteristics of Fe-Co-Ni-Cu alloy are effectively changed, and its acid etching performance is improved, thereby realizing the rapid leaching of Fe-Co-Ni-Cu alloy. Therefore, the process is more economical.

[0032] (2) 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 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. Detailed Implementation

[0033] 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.

[0034] 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.

[0035] 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.

[0036] Example 1:

[0037] A method for leaching valuable metals from an iron-cobalt-copper-nickel alloy includes the following steps:

[0038] (1) The iron-cobalt-copper-nickel alloy contained in the copper-cobalt ore smelting product is copper-cobalt white alloy (the main components have mass contents of Co 38.87%, Fe 32.45%, Cu 13.45%, and Si 10.15%). The copper-cobalt white alloy is placed in an electric furnace to melt and form an alloy melt.

[0039] (2) Add iron-phosphorus alloy (0.35 times the mass of copper-cobalt white alloy) to the above alloy melt and heat at 1600℃ for 30 min to melt.

[0040] (3) The melt described in step (2) is atomized into powder by water atomization. The mass fraction of P in the alloy powder is 3.5%, and the particle size of the alloy powder is ≤150μm.

[0041] (4) The alloy powder from step (3) was leached by sulfuric acid oxidation. Oxygen was used as the oxidant. The amount of sulfuric acid was 1.7 times the theoretical amount required to leach out all cobalt and copper (which is inconsistent with the theoretical amount for leaching copper, cobalt and nickel as specified earlier). The leaching temperature was 75℃ and the leaching time was 2.0h. The leaching rates of copper and cobalt were 98.17% and 99.22%, respectively. The mass fraction of Fe in the iron oxide slag (dry weight) was 47.55%, and the P content in the slag was 4.5%.

[0042] Example 2:

[0043] A method for leaching valuable metals from an iron-cobalt-copper-nickel alloy includes the following steps:

[0044] (1) The iron-cobalt-copper-nickel alloy contained in the product 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.

[0045] (2) Add red phosphorus (0.05 times the mass of the iron-cobalt-copper-nickel alloy) to the above alloy melt and heat it at 1550℃ for 30 minutes.

[0046] (3) The melt described in step (2) is atomized into granules by water atomization. The mass fraction of P in the alloy particles is 5%, and the particle size of the alloy particles is ≤2cm.

[0047] (4) The alloy particles from step (3) are first finely ground into powder, and then leached with 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 98.78%, 99.43% and 99.20% respectively. The mass fraction of Fe in the iron oxide slag (dry weight) is 53.51% and the P content in the slag is 6.7%.

[0048] Example 3:

[0049] A method for leaching valuable metals from an iron-cobalt-copper-nickel alloy includes the following steps:

[0050] (1) The iron-cobalt-copper-nickel 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.

[0051] (2) Add red phosphorus (0.15 times the mass of the iron-cobalt-copper alloy) to the above alloy melt, keep it at 1570℃ for 40 minutes, and introduce nitrogen gas to stir the molten pool during the melting process.

[0052] (3) The melt described in step (2) is atomized into powder by water atomization. The particle size of the alloy powder is ≤150μm and the mass fraction of P in the alloy particles is 10%.

[0053] (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 and copper. The leaching temperature was 55°C and the leaching time was 6.0 h. The leaching rates of copper and cobalt were 98.15% and 99.67%, respectively. The mass fraction of Fe in the iron oxide slag (dry weight) was 56.11%, and the P content in the slag was 13.8%.

[0054] Comparative Example 1:

[0055] 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 are added. It is directly water-atomized into powder. The particle size of the alloy powder is ≤150μm. The mass fraction of P in the alloy particles is 0.3%. The remaining steps and processes are the same as those in Example 3. When the leaching time is 6.0h, the leaching rates of copper and cobalt are 75.78% and 86.48%, respectively, which are much lower than the leaching rates of Example 3.

Claims

1. A method for leaching valuable metals from an iron-cobalt-copper-nickel alloy, characterized in that, Includes the following steps: (1) The iron-cobalt-copper-nickel alloy is melted to form an alloy melt; (2) Add phosphorus-containing material to the alloy melt and keep it at a certain temperature for a period of time to obtain phosphorus alloy melt; the mass of the added phosphorus-containing material is 0.03-0.5 times the mass of the iron-cobalt-copper-nickel alloy; the phosphorus-containing material is one or more of phosphorus bronze, phosphorus-containing pig iron, phosphorus-containing cast iron, yellow phosphorus, red phosphorus, phosphorus pentoxide, apatite, calcium phosphate, iron phosphate, nickel phosphate, calcium pyrophosphate, calcium hydrogen phosphate, calcium dihydrogen phosphate, calcium fluorophosphate, phosphate concentrate, calcium magnesium phosphate fertilizer, superphosphate, struvite, ferric phosphorus, and ferric phosphate; (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; oxygen-containing gas is introduced during the leaching process.

2. The method for leaching valuable metals from an iron-cobalt-copper-nickel alloy according to claim 1, characterized in that: In step (1), the iron-cobalt-copper-nickel alloy is melted using an electric furnace or a converter.

3. The method for leaching valuable metals from an iron-cobalt-copper-nickel alloy according to claim 1, characterized in that: In step (3), the mass fraction of P in the phosphorus alloy powder is ≥6%.

4. The method for leaching valuable metals from an iron-cobalt-copper-nickel alloy according to claim 1, characterized in that: In step (2), the heat preservation time is ≥15min.

5. The method for leaching valuable metals from an iron-cobalt-copper-nickel alloy 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.

6. The method for leaching valuable metals from an iron-cobalt-copper-nickel alloy 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 leaching copper, cobalt, and nickel, and the acid leaching temperature is ≥50℃.

7. The method for leaching valuable metals from an iron-cobalt-copper-nickel alloy 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℃.

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