A process for atmospheric leaching of copper, nickel, cobalt from sulphur bearing alloys and in situ precipitation of iron
By reacting nitric acid solution with sulfur-containing alloys under normal pressure and controlling the reaction parameters, the problems of poor iron suppression and high energy consumption in existing technologies have been solved. This has enabled efficient recovery of copper, nickel, and cobalt, as well as in-situ precipitation and separation of iron, thus improving production efficiency.
Patent Information
- Application Number
- CN202610918205.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-24
- Publication Date
- 2026-07-24
AI Technical Summary
Existing technologies for recovering valuable metals from nickel converter slag include poor iron inhibition, long leaching time, and high energy consumption in atmospheric pressure leaching, while pressurized leaching equipment requires high investment and has high safety requirements.
By reacting nitric acid solution with sulfur-containing alloys under normal pressure, and by controlling parameters such as the leaching reaction temperature, liquid-solid ratio, and stirring speed, efficient leaching of copper, nickel, and cobalt can be achieved. During the reaction, hydrated potassium ferric sulfate precipitate is generated to achieve in-situ precipitation and separation of iron.
It achieves copper leaching rates of over 85%, nickel leaching rates of over 90%, cobalt inhibition rates of over 90%, and iron inhibition rates of over 80%, improving the recovery efficiency of valuable metals and simplifying subsequent iron removal processes.
Smart Images
Figure CN122445943A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of hydrometallurgical technology, specifically relating to a method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and immersing iron in situ. Background Technology
[0002] With the increasing depletion of high-quality mineral resources, the recovery of valuable metals from secondary resources has become a research hotspot. Nickel, copper, and cobalt, as strategic metals, have wide applications in defense, aerospace, and new energy batteries. Nickel converter slag is a typical secondary resource, which is usually enriched into sulfur-containing alloys through reduction smelting, and then the valuable metals are recovered through pressure leaching. However, pressure leaching has problems such as high equipment investment, high energy consumption, and high safety requirements.
[0003] In recent years, iron capture technology has been used to recover Ni, Co, and Cu from converter slag. The resulting sulfur-containing alloys have high iron content and complex phases, posing challenges to subsequent wet processing. Although existing atmospheric pressure leaching processes have made some progress, they generally suffer from poor iron inhibition, long leaching times, and high energy consumption. Therefore, developing an efficient, mild, and economical atmospheric pressure leaching method is of great significance. Summary of the Invention
[0004] The purpose of this invention is to solve the above-mentioned problems and provide a method for leaching valuable metals from sulfur-containing alloys under normal pressure and precipitating iron in situ, achieving a copper leaching rate of over 85%, a nickel leaching rate of over 90%, a cobalt inhibition rate of over 90%, and an iron inhibition rate of over 80%. Furthermore, it can simultaneously achieve in-situ precipitation and separation of iron, resulting in high production efficiency.
[0005] The specific solution of the present invention is as follows: a method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and performing in-situ iron deposition, the method comprising: The sulfur-containing alloy was crushed, ball-milled, and then mixed with nitric acid solution. The mixture was then subjected to a leaching reaction under normal pressure. After solid-liquid separation, a leaching solution containing copper, nickel, and cobalt and a leaching residue containing iron were obtained. The concentration of the nitric acid solution is 2.5~4 mol / L; The leaching reaction temperature is 50~90℃; The liquid-to-solid ratio of the leaching reaction is 7-15:1 mL / g.
[0006] In this invention, the preferred method for preparing the sulfur-containing alloy includes: crushing the sulfur-containing alloy raw material into 5-8 mm particles using a jaw crusher, and then ball milling it using a planetary ball mill. During ball milling, it is preferable to pause for 1 minute after every 2 minutes of milling to prevent excessively high sample temperature from causing phase changes. After ball milling, the sample is passed through a 200-mesh standard sieve, and the material passing through the sieve is used as the experimental raw material.
[0007] As a preferred embodiment, in the above-mentioned method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and then depositing iron in situ, the leaching reaction time is 60-120 min.
[0008] As a preferred embodiment, the above-described method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and then performing in-situ iron deposition results in a ball-milled sulfur-containing alloy with a particle size of -200 mesh (i.e., less than 75 μm). The smaller particle size significantly increases the reaction surface area, disrupts the dense structure of the alloy, and facilitates the penetration of nitric acid solution into the metal phase, thereby accelerating the leaching reaction rate.
[0009] The above-described method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and then performing in-situ iron deposition, wherein the sulfur-containing alloy comprises, by mass fraction: Cu 20-25%, Ni 24-28%, Co 2-4%, Fe 28-34%, S 10-15%, with the balance being impurities. As a specific example, a typical composition of the sulfur-containing alloy is: Cu 22.5%, Ni 25.68%, Co 3.14%, Fe 31.18%, S 12.78%, and small amounts of impurities such as Si, Ca, Mg, and Al.
[0010] As a preferred embodiment, in the above-described method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and then performing in-situ iron deposition, the leaching reaction is carried out under stirring conditions at a stirring speed of 120-200 rpm. An appropriate stirring speed ensures thorough mixing of the solid and liquid phases, prevents particle sedimentation, and enhances the mass transfer process.
[0011] In the above-mentioned method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and precipitating iron in situ, the iron in the leaching residue exists in the form of hydrated potassium ferric sulfate, with the chemical formula (H3O)Fe3(SO4)2(OH)6.
[0012] Too low a nitric acid concentration (e.g., 2 mol / L) results in insufficient oxidation, potentially leading to low leaching rates of Cu, Ni, and Co; too high a concentration may increase acid consumption and costs. Increasing the reaction temperature improves reaction kinetics, but excessively high temperatures may increase energy consumption. The reaction is extremely slow at low temperatures (e.g., 25°C). Too short a reaction time leads to incomplete reaction; too long a time offers limited improvement in leaching rate and may damage the already formed potassium ferrous sulfate structure. A liquid-to-solid ratio that is too low (e.g., 5:1) may result in high pulp viscosity, hindered mass transfer, and a sharp decrease in leaching rate.
[0013] As a preferred embodiment, in the above-mentioned method for leaching copper, nickel, and cobalt from sulfur-containing alloys under atmospheric pressure and performing in-situ iron deposition, the liquid-to-solid ratio of the leaching reaction is 8-13:1 mL / g. As a further preferred embodiment, in the above-mentioned method for leaching copper, nickel, and cobalt from sulfur-containing alloys under atmospheric pressure and performing in-situ iron deposition, the leaching reaction temperature is 70-85℃; the leaching reaction time is 90-120 min; and the liquid-to-solid ratio of the leaching reaction is 8-12:1 mL / g. As an even more preferred embodiment, in the above-mentioned method for leaching copper, nickel, and cobalt from sulfur-containing alloys under atmospheric pressure and performing in-situ iron deposition, the concentration of the nitric acid solution is 3-4 mol / L; the leaching reaction temperature is 83-84℃; the leaching reaction time is 92-98 min; and the liquid-to-solid ratio of the leaching reaction is 9-11:1 mL / g.
[0014] According to the present invention, in the most preferred embodiment, the concentration of the nitric acid solution is 3.5 mol / L; the leaching reaction temperature is 83.5°C; the leaching reaction time is 94.7 min; and the liquid-to-solid ratio of the leaching reaction is 10:1 mL / g. At this time, the leaching rate of copper in the leachate reaches 96.4% or more, the leaching rate of nickel reaches 98.0% or more, the leaching rate of cobalt reaches 97.9% or more, and the inhibition rate of iron reaches 87.1% or more.
[0015] The main reaction equation for the leaching process can be: 3Cu+8HNO3=3Cu(NO3)2+2NO(g)+4H2O(1) 3Ni+8HNO3=3Ni(NO3)2+2NO(g)+4H2O(2) 3Co+8HNO3=3Co(NO3)2+2NO(g)+4H2O(3) Fe+4HNO3=Fe(NO3)3+NO(g)+2H2O(4) 3Cu2S+22HNO3=6Cu(NO3)2+3H2SO4+10NO(g)+8H2O(5) Ni3S2+8HNO3=3Ni(NO3)2+2S+2NO(g)+4H2O(6) FeS+6HNO3=Fe(NO3)3+H2SO4+3NO(g)+2H2O(7) Under optimized conditions, the Fe produced in the reaction 3+ Further hydrolysis and combination with sulfate ions produce hydrated potassium ferric sulfate precipitate: 3Fe 3+ +2SO4 2- +6H2O+H3O + =(H3O)Fe3(SO4)2(OH)6(s)+5H+ (8).
[0016] Compared with the prior art, the present invention has at least the following beneficial effects: This invention utilizes nitric acid to leach sulfur-containing alloys under normal pressure. The oxidizing properties of nitric acid destroy the alloy phase and sulfide phase in the sulfur-containing alloy, allowing copper, nickel, and cobalt to enter the leachate in ionic form. Simultaneously, under optimized conditions, the sulfur in the material itself is oxidized to sulfate, which combines with iron to form hydrated potassium ferric sulfate precipitate, achieving in-situ synchronous separation of iron. This improves the recovery efficiency of valuable metals and simplifies the subsequent iron removal process.
[0017] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description
[0018] Figure 1 This is a process flow diagram of one embodiment of the present invention.
[0019] Figure 2 The XRD and XPS analysis results are from one embodiment of the present invention.
[0020] Figure 3 This is a SEM-EDS analysis result of an embodiment of the present invention. Detailed Implementation
[0021] The following description provides numerous specific details to offer a more thorough understanding of the technical solutions provided by this invention. However, it will be apparent to those skilled in the art that the technical solutions provided by this invention can be implemented without one or more of these details.
[0022] In this embodiment of the invention, after the leaching reaction is completed, a circulating water vacuum pump is used for solid-liquid separation. The obtained filter residue is washed three times with deionized water, and the filtrate and washing liquid are combined, diluted to a final volume with deionized water, and then the elemental content is analyzed. The leaching residue is dried at 120°C for 12 h before characterization analysis.
[0023] The process flow diagram of an embodiment of the present invention is as follows: Figure 1 As shown: After crushing, ball milling, and drying the sulfur-containing alloy, it is mixed with nitric acid solution and leached under normal pressure. After solid-liquid separation, a leaching solution containing Cu, Ni, and Co and an iron-containing leaching residue are obtained; the iron in the leaching residue exists in the form of hydrated potassium ferric alum.
[0024] The following detailed description, in conjunction with embodiments, illustrates the method provided by the present invention for leaching valuable metals from sulfur-containing alloys under normal pressure and performing in-situ iron deposition; however, these descriptions should not be construed as limiting the scope of protection of the present invention.
[0025] In the examples and comparative examples, the ball mill model is QM-3SP2, a planetary ball mill; the leaching reaction is carried out on a constant temperature heated magnetic stirrer, model DF-101S.
[0026] By mass fraction, the composition of the sulfur-containing alloys in the examples and comparative examples is as follows: Cu 22.5%, Ni 25.68%, Co 3.14%, Fe 31.18%, S 12.78%, Si 0.18%, Ca 0.13%, Mg 0.06%, Al 0.03%, with the balance being other impurities.
[0027] Example 1 (1) The sulfur-containing alloy is crushed into 5-8 mm particles by a jaw crusher and then put into a planetary ball mill for ball milling (in order to prevent the sample temperature from being too high and causing phase change during the grinding process, the intermittent ball milling method is adopted: ball milling for 2 min, then pausing cooling for 1 min). After ball milling, the sample is passed through a 200-mesh standard sieve. The powder under the sieve is dried in an oven at 120℃ for 24 h for later use.
[0028] (2) Weigh 5 g of the sulfur-containing alloy powder accurately using an analytical balance and place it in a reaction vessel.
[0029] (3) Add a pre-prepared 3 mol / L nitric acid solution at a liquid-to-solid ratio of 10:1 mL / g, and stir and leach at a constant temperature of 70℃ for 90 min at a stirring speed of 120 rpm.
[0030] (4) After the reaction is completed, a circulating water vacuum pump is used for filtration. The filter residue is washed three times with deionized water. The filtrate and washing liquid are combined and diluted to 250 mL with deionized water in a volumetric flask.
[0031] (5) The contents of Cu, Ni, Co and Fe in the leachate were analyzed by atomic absorption spectrometry, and the leaching rate of each element and the inhibition rate of iron were calculated.
[0032] After the above process, the Cu leaching rate was 86.9%, the Ni leaching rate was 93.9%, the Co leaching rate was 93.3%, and the iron inhibition rate was over 85%. XRD analysis showed that hydrated potassium ferric alum phase was present in the leaching residue.
[0033] Example 2 (1) Prepare sulfur-containing alloy powder in the same way as step (1) in Example 1.
[0034] (2) Weigh 5 g of sulfur-containing alloy powder and add it to a pre-prepared 3 mol / L nitric acid solution at a liquid-solid ratio of 10:1 mL / g. Stir and leach at a constant temperature of 85℃ for 90 min at a stirring speed of 120 rpm.
[0035] (3) Perform post-processing and testing as in steps (4)-(5) of Example 1.
[0036] After the above process, the Cu leaching rate was 89.2%, the Ni leaching rate was 94.5%, the Co leaching rate was 94.1%, and the iron inhibition rate was 86.3%.
[0037] Example 3 (1) Prepare sulfur-containing alloy powder in the same way as step (1) in Example 1.
[0038] (2) Weigh 5 g of sulfur-containing alloy powder and add it to a pre-prepared 3 mol / L nitric acid solution at a liquid-solid ratio of 10:1 mL / g. Stir and leach at a constant temperature of 70℃ for 120 min at a stirring speed of 120 rpm.
[0039] (3) Perform post-processing and testing as in steps (4)-(5) of Example 1.
[0040] After the above process, the Cu leaching rate was 87.3%, the Ni leaching rate was 94.2%, the Co leaching rate was 93.8%, and the iron inhibition rate was 84.7%.
[0041] Example 4 (Response Surface Optimization Conditions) (1) Prepare sulfur-containing alloy powder in the same way as step (1) in Example 1.
[0042] (2) Weigh 5 g of sulfur-containing alloy powder and add it to a pre-prepared 3.5 mol / L nitric acid solution at a liquid-solid ratio of 10:1 mL / g. Stir and leach at a constant temperature of 83.5℃ for 94.7 min at a stirring speed of 120 rpm.
[0043] (3) Perform post-processing and testing as in steps (4)-(5) of Example 1.
[0044] After the above process, the Cu leaching rate was 96.4%, the Ni leaching rate was 98.0%, the Co leaching rate was 97.9%, the iron inhibition rate was 87.1%, and the iron concentration in the leachate was below 2.3 g / L. See also... Figure 2 , Figure 3 XRD analysis showed obvious characteristic peaks of hydrated potassium ferric sulfate in the leaching residue. SEM-EDS analysis showed that Fe, S, and O elements were highly overlapped in the residue. XPS analysis indicated that sulfur in the residue was mainly in the form of SO4. 2- It exists in form.
[0045] Comparative Example 1 The difference from Example 1 is that 3 mol / L sulfuric acid was used instead of nitric acid for leaching, while other conditions were the same as in Example 1.
[0046] After the above process, the Cu leaching rate was less than 20%, the Ni leaching rate was 54%, the Co leaching rate was 47.5%, the iron inhibition rate was low, and no potassium ferrous sulfate phase was observed in XRD analysis.
[0047] Comparative Example 2 The difference from Example 1 is that 3 mol / L hydrochloric acid was used instead of nitric acid for leaching, while other conditions were the same as in Example 1.
[0048] After the above process, the Cu leaching rate is less than 15%, the Ni leaching rate is 59%, the Co leaching rate is 61.3%, and the iron inhibition rate is low.
[0049] Comparative Example 3 The difference from Example 1 is that the leaching temperature is 25°C, while the other conditions are the same as in Example 1.
[0050] After the above process, the Cu leaching rate is less than 10%, the Ni leaching rate is 78.7%, the Co leaching rate is 85.8%, and the iron inhibition rate is low.
[0051] Comparative Example 4 (the main difference from Example 1 is that the concentration of the nitric acid solution is 2 mol / L) (1) Prepare sulfur-containing alloy powder in the same way as step (1) in Example 1.
[0052] (2) Weigh 5 g of sulfur-containing alloy powder and add it to a pre-prepared 2 mol / L nitric acid solution at a liquid-solid ratio of 10:1 mL / g. Stir and leach at a constant temperature of 70℃ for 90 min at a stirring speed of 120 rpm.
[0053] (3) Perform post-processing and testing as in steps (4)-(5) of Example 1.
[0054] After the above process, the Cu leaching rate was 67.8%, the Ni leaching rate was 83.3%, the Co leaching rate was 82.9%, and the iron inhibition rate was 79.5%.
[0055] Comparative Example 5 (the main difference from Example 1 is the liquid-to-solid ratio of 5:1 mL / g) (1) Prepare sulfur-containing alloy powder in the same way as step (1) in Example 1.
[0056] (2) Weigh 5 g of sulfur-containing alloy powder and add it to a pre-prepared 3 mol / L nitric acid solution at a liquid-solid ratio of 5:1 mL / g. Stir and leach at a constant temperature of 70℃ for 90 min at a stirring speed of 120 rpm.
[0057] (3) Perform post-processing and testing as in steps (4)-(5) of Example 1.
[0058] After the above process, the Cu leaching rate was 73.4%, the Ni leaching rate was 89.4%, the Co leaching rate was 88.6%, and the iron inhibition rate was 73.2%.
[0059] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and performing in-situ iron deposition, characterized in that, The method includes: The sulfur-containing alloy was crushed, ball-milled, and then mixed with nitric acid solution. The mixture was then subjected to a leaching reaction under normal pressure. After solid-liquid separation, a leaching solution containing copper, nickel, and cobalt and a leaching residue containing iron were obtained. The concentration of the nitric acid solution is 2.5~4 mol / L; The leaching reaction temperature is 50~90℃; The liquid-to-solid ratio of the leaching reaction is 7-15:1 mL / g.
2. The method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and performing in-situ iron deposition according to claim 1, characterized in that, The leaching reaction takes 60 to 120 minutes.
3. The method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and performing in-situ iron deposition according to claim 1, characterized in that, The particle size of the sulfur-containing alloy after ball milling is -200 mesh.
4. The method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and performing in-situ iron deposition according to claim 1, characterized in that, The sulfur-containing alloy comprises, by mass fraction: Cu 20-25%, Ni 24-28%, Co 2-4%, Fe 28-34%, S 10-15%, with the balance being impurities.
5. The method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and performing in-situ iron deposition according to claim 1, characterized in that, The leaching reaction is carried out under stirring conditions at a stirring speed of 120-200 rpm.
6. The method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and performing in-situ iron deposition according to claim 1, characterized in that, The iron in the leaching residue exists in the form of hydrated potassium ferric sulfate, with the chemical formula (H3O)Fe3(SO4)2(OH)6.
7. The method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and performing in-situ iron deposition according to claim 1, characterized in that, The liquid-to-solid ratio of the leaching reaction is 8-13:1 mL / g.
8. The method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and performing in-situ iron deposition according to claim 1, characterized in that, Satisfy at least one of the following characteristics: The leaching reaction temperature is 70-85℃; The leaching reaction time is 90-120 min; The liquid-to-solid ratio of the leaching reaction is 8-12:1 mL / g.
9. The method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and performing in-situ iron deposition according to claim 8, characterized in that, The concentration of the nitric acid solution is 3-4 mol / L; The leaching reaction temperature is 83-84℃; The leaching reaction time is 92-98 min; The liquid-to-solid ratio of the leaching reaction is 9-11:1 mL / g.
10. The method for leaching copper, nickel, and cobalt from sulfur-containing alloys under normal pressure and performing in-situ iron deposition according to claim 1, characterized in that, The leaching solution has a copper leaching rate of over 85%, a nickel leaching rate of over 90%, a cobalt leaching rate of over 90%, and an iron inhibition rate of over 80%.