Method for separating iron and scandium from cobalt-nickel hydroxide raw material

Abstract

The invention discloses a method for separating iron and scandium from cobalt-nickel hydroxide raw materials, and relates to the technical field of hydrometallurgy. According to the method, nickel and cobalt are reduced and leached with a proper amount of hydrogen peroxide under the acidic condition, the pH value of feed liquid is adjusted after the reaction is finished, and iron and scandium are co-precipitated to form mixed slag to be separated out; the mixed slag is completely dissolved with sulfuric acid and an oxidizing agent, the solution is pumped into a high-pressure kettle, ferrous iron in the solution is converted into insoluble hydrated iron oxide red under the action of certain oxygen atmosphere pressure and temperature, scandium is still left in the solution, at the moment, the pH value of the solution is adjusted, and then pure scandium hydroxide is precipitated; the method has the characteristics that the trace scandium element is effectively separated from the cobalt-nickel hydroxide raw material to the greatest extent by adopting a simple process and equipment, and meanwhile, the impurity iron is converted into an iron oxide red material commonly used in the building material industry.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for separating iron and scandium from cobalt-nickel hydroxide raw materials. Background Art

[0002] Scandium is an important strategic resource, widely used in lighting industry, fuel cells, alloy industry, ceramic materials, catalytic chemistry, nuclear energy industry, agricultural breeding and other fields. Scandium is usually associated with minerals, with low content and great difficulty in extraction. Therefore, it is of great significance to prepare a reasonable and efficient process route for extracting scandium.

[0003] Existing methods for extracting scandium include extraction, adsorption, ion exchange and chemical precipitation. Among them, the extraction method is a widely used method in industry. Its advantages are mature process technology and suitability for industrial production; its disadvantages are large investment, small capacity of extractant, low utilization rate, high cost of scandium recovery and poor quality; the advantage of the resin adsorption method is that it can enrich scandium in low-grade solutions, with little pollution and low equipment requirements; the disadvantages are high investment, low adsorption capacity, high water resource consumption and poor selectivity; the advantage of the membrane separation method is high separation efficiency and the preparation of high-purity substances; the disadvantages are complex operation, long production cycle, regular replacement of ion exchange membranes, and high maintenance and production costs; and the chemical precipitation method has the advantages of low investment, mild reaction conditions, mature and stable technology, and high degree of equipment universality, and has become a current research hotspot. Summary of the invention

[0004] The object of the present invention is to provide a method for separating iron and scandium from raw materials of cobalt-nickel hydroxide to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solution: a method for separating iron scandium from cobalt nickel hydroxide raw materials, comprising the following preparation steps: (1) crushing and grinding cobalt nickel hydroxide to less than 120 μm; (2) mixing the ground cobalt nickel hydroxide raw material with bottom water at a liquid-to-solid ratio of 1-5:1 and heating to 50-80°C; (3) Using sulfuric acid to adjust the pH of the system to 1.5-3.0, and adding a reducing agent to dissolve all the raw materials; adding a neutralizing agent to the system to adjust the pH, so that the iron and scandium in the system are co-precipitated to form solid slag, followed by solid-liquid separation, and the filtered cobalt and nickel solutions directly enter the extraction section, and the separated solid slag is washed with water and then filtered to recover the washing water and solid slag separately for use; (4) the washing water is returned to step (2) for cyclic pulping, and the recovered solid residue is re-slurried with water, and then acid and a reducing agent are added to dissolve it again into a mixed solution containing ferrous ions and scandium ions; (5) The mixed solution after dissolution in step (4) is sent into an autoclave, and an appropriate amount of oxygen is introduced to oxidize the iron, and a certain oxygen partial pressure is maintained. The reaction is carried out at a high temperature for 2 to 6 hours, and the iron slag and a relatively pure scandium salt solution are obtained by filtering; (6) adjusting the pH of the scandium salt solution generated in step (5) with a precipitant, reacting for 0.5 to 2.0 hours, and precipitating a scandium-rich slag; (7) The iron slag formed in step (5) is subjected to magnetic separation, rinsing, drying and screening to obtain a finished product.

[0006] Furthermore, the reducing agent in step (3) is sulfite or hydrogen peroxide solution.

[0007] Furthermore, the neutralizing agent in step (3) is a cobalt nickel hydroxide raw material and one of sodium carbonate, sodium hydroxide, and sodium bicarbonate, and the pH value after neutralization is 3 to 6; Furthermore, in step (4), the acid is sulfuric acid and the reducing agent is sulfurous acid or sulfite.

[0008] Furthermore, the oxygen partial pressure in step (5) is 0.1-0.3 MPa, the reaction temperature is 130-180° C., and the main component of the scandium salt solution is scandium sulfate.

[0009] Furthermore, the precipitant in step (6) is one or more of sodium hydroxide, sodium carbonate or sodium oxalate.

[0010] Furthermore, in step (6), the reaction is adjusted to a pH value of 4 to 5; Furthermore, the quality of the finished product of red iron oxide in step (7) is that the iron oxide content reaches 86.5%, the specific gravity is 5.16, and it meets the first-class product standards.

[0011] Furthermore, the rinse water generated in step (7) is collected and used as bottom water, and is returned to the system step (2) to be used in slurry with the cobalt nickel hydroxide raw material.

[0012] Furthermore, the main components of the cobalt nickel hydroxide include Co 3.13%, Ni 37.13%, Cu 0.12%, Fe 0.37%, Mn 5.23%, Zn 0.52%, Sc 0.06% Compared with the prior art, the beneficial effects achieved by the present invention are: (1) Scandium is precipitated from the system by adjusting the pH, avoiding the use of high-cost materials such as adsorbents and ion exchange resins, avoiding the use of extractants to extract scandium, reducing the number of subsequent extraction stages, and alleviating the pressure of the extraction system. The reaction conditions are mild, the technical risks are low, and the equipment investment is small. In addition, more than 95% of iron impurities can be removed, and the scandium extraction rate can reach more than 98%; (2) The present invention adopts crushing and grinding, leaching, oxygen pressure iron removal and precipitation treatment to extract a small amount of scandium element from cobalt nickel hydroxide. Multiple leaching treatments can achieve simple and effective separation of iron and cobalt nickel hydroxide raw materials, reduce the loss of scandium during subsequent impurity removal, and effectively avoid the difficulty of subsequent iron removal, thereby extracting the scandium element to the greatest extent. The wastewater and waste materials generated can be fully utilized and re-enter the production and processing system to achieve recycling, so as to meet the closed-loop circulation of the entire process. There is no discharge of three wastes during the process, the process is green and environmentally friendly, and at the same time, the addition of raw materials is reduced, and the investment cost and production cost are low. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 It is a schematic diagram of the process flow of the present invention. DETAILED DESCRIPTION

[0014] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0015] Example 1; (1) crushing and grinding cobalt nickel hydroxide to less than 120 μm; (2) The ground cobalt-nickel hydroxide raw material is mixed with bottom water and then fed into a reactor with a liquid-to-solid ratio of 5:1, slurried, and then heated to 50°C. The pH is adjusted to 1.5 with sulfuric acid, and 30% hydrogen peroxide is added to dissolve all the raw materials. Cobalt-nickel hydroxide is then added to adjust the pH to 2, and then sodium hydroxide is added to adjust the pH to 3. A leaching process is performed for 1 hour. After the leaching is completed, solid-liquid separation is performed, and the filtered cobalt-nickel solution directly enters the extraction section. The separated solid residue is washed with water and then the washing water and solid residue are recovered separately through a filtering device for standby use; (3) the washing water is returned to step (2) for cyclic beating, the recovered solid slag is re-slurried with water at a liquid-to-solid ratio of 5:1, industrial sulfuric acid and 30% by mass hydrogen peroxide are added thereto to completely dissolve the slag into a mixed solution containing ferrous ions and scandium ions; (4) adding the mixed solution into an autoclave at a rotation speed of 300 rpm, introducing oxygen to remove iron by oxygen pressure, maintaining the oxygen pressure at 0.1 MPa, and reacting at 150° C. for 4 h; after the iron removal is completed, solid-liquid separation is performed to obtain iron slag and a second-stage filtrate; the iron slag is subjected to magnetic separation, rinsing, drying, and screening to obtain a finished product, and the generated rinsing water is collected and used as bottom water and returned to the system step (2) for slurrying with the cobalt-nickel hydroxide raw material; (5) The pH value of the second-stage filtrate was adjusted to 4 with sodium hydroxide and reacted at 30°C for 2 h to obtain scandium slag.

[0016] Example 2: (1) crushing and grinding cobalt nickel hydroxide to less than 120 μm; (2) The ground cobalt-nickel hydroxide raw material is mixed with bottom water and then fed into a reactor with a liquid-to-solid ratio of 4:1, slurried, and then heated to 60°C. The pH is adjusted to 2 with sulfuric acid, and 30% by mass of hydrogen peroxide is added to dissolve all the raw materials. Cobalt-nickel hydroxide is then added to adjust the pH to 2.5, and then sodium hydroxide is added to adjust the pH to 4. A leaching process is performed for 1 hour. After the leaching is completed, solid-liquid separation is performed, and the filtered cobalt-nickel solution directly enters the extraction section. The separated solid residue is washed with water and then the washing water and solid residue are recovered separately through a filtering device for standby use; (3) the washing water is returned to step (2) for cyclic pulping, the recovered solid slag is re-slurried with water at a liquid-to-solid ratio of 4:1, industrial sulfuric acid and 30% by mass hydrogen peroxide are added thereto to completely dissolve the slag into a mixed solution containing ferrous ions and scandium ions; (4) adding the mixed solution into an autoclave at a rotation speed of 400 rpm, introducing oxygen to remove iron by oxygen pressure, maintaining the oxygen pressure at 0.2 MPa, and reacting at 160° C. for 5 h; after the iron removal is completed, solid-liquid separation is performed to obtain iron slag and a second-stage filtrate; the iron slag is subjected to magnetic separation, rinsing, drying, and screening to obtain a finished product, and the generated rinsing water is collected and used as bottom water and returned to the system step (2) for slurrying with the cobalt-nickel hydroxide raw material; (5) The pH value of the second-stage filtrate was adjusted to 4.5 with sodium bicarbonate and reacted at 40°C for 1 h to obtain scandium slag.

[0017] Example 3; (1) crushing and grinding cobalt nickel hydroxide to less than 120 μm; (2) The ground cobalt-nickel hydroxide raw material is mixed with bottom water and then fed into a reactor with a liquid-to-solid ratio of 5:1, slurried, and then heated to 70°C. The pH is adjusted to 2.5 with sulfuric acid, and 30% hydrogen peroxide is added to dissolve all the raw materials. Cobalt-nickel hydroxide is then added to adjust the pH to 3, and then sodium hydroxide is added to adjust the pH to 4.5. A leaching process is performed for 1.5 hours. After the leaching is completed, solid-liquid separation is performed, and the filtered cobalt-nickel solution directly enters the extraction section. The separated solid residue is washed with water and then the washing water and solid residue are recovered separately through a filtering device for standby use; (3) the washing water is returned to step (2) for cyclic beating, the recovered solid slag is re-slurried with water at a liquid-to-solid ratio of 5:1, industrial sulfuric acid and 30% by mass hydrogen peroxide are added thereto to completely dissolve the slag into a mixed solution containing ferrous ions and scandium ions; (4) adding the mixed solution into an autoclave at a rotation speed of 400 rpm, introducing oxygen to remove iron by oxygen pressure, maintaining the oxygen pressure at 0.3 MPa, and reacting at 170° C. for 6 h; after the iron removal is completed, solid-liquid separation is performed to obtain iron slag and a second-stage filtrate; the iron slag is subjected to magnetic separation, rinsing, drying, and screening to obtain a finished product, and the generated rinsing water is collected and used as bottom water and returned to the system step (2) for slurrying with the cobalt-nickel hydroxide raw material; (5) The pH value of the second-stage filtrate was adjusted to 5 with sodium carbonate and reacted at 50°C for 1.5 h to obtain scandium slag.

[0018] Example 4; (1) crushing and grinding cobalt nickel hydroxide to less than 120 μm; (2) The ground cobalt-nickel hydroxide raw material is mixed with bottom water and then fed into a reactor with a liquid-to-solid ratio of 5:1, slurried, and then heated to 80°C. The pH is adjusted to 3 with sulfuric acid, and 30% hydrogen peroxide is added to dissolve all the raw materials. Cobalt-nickel hydroxide is then added to adjust the pH to 4, and then sodium hydroxide is added to adjust the pH to 5. A leaching process is performed for 2 hours. After the leaching is completed, solid-liquid separation is performed, and the filtered cobalt-nickel solution directly enters the extraction section. The separated solid residue is washed with water and then the washing water and solid residue are recovered separately through a filtering device for standby use; (3) the washing water is returned to step (2) for cyclic beating, the recovered solid slag is re-slurried with water at a liquid-to-solid ratio of 5:1, industrial sulfuric acid and 30% by mass hydrogen peroxide are added thereto to completely dissolve the slag into a mixed solution containing ferrous ions and scandium ions; (4) adding the mixed solution into an autoclave at a rotation speed of 300 rpm, introducing oxygen to remove iron by oxygen pressure, maintaining the oxygen pressure at 0.3 MPa, and reacting at 180° C. for 8 h; after the iron removal is completed, solid-liquid separation is performed to obtain iron slag and a second-stage filtrate; the iron slag is subjected to magnetic separation, rinsing, drying, and screening to obtain a finished product, and the generated rinsing water is collected and used as bottom water and returned to the system step (2) for slurrying with the cobalt-nickel hydroxide raw material; (5) The pH value of the second-stage filtrate was adjusted to 5 with sodium carbonate and reacted at 50°C for 2 h to obtain scandium slag.

[0019] Effect example Table 1 below shows the performance analysis results of the main raw material components of the iron slag and scandium slag used in Examples 1 to 4 of the present invention.

[0020] Table 1

[0021] It can be obtained from the data in the table that the method can remove at least 95% of iron impurities, and the extraction rate of scandium is as high as 98%. The method has a good effect of separating iron and scandium. The present invention adopts leaching, oxygen pressure iron removal and precipitation treatment to extract a small amount of scandium in cobalt nickel hydroxide. Multiple leaching treatments are performed to achieve simple and effective separation of iron and cobalt nickel hydroxide raw materials, reduce the loss of scandium during subsequent impurity removal, and effectively avoid the difficulty of subsequent iron removal, thereby extracting the scandium element to the greatest extent, and the waste water and waste generated can be fully utilized and re-enter the production and processing system to achieve recycling, so as to meet the full process closed-loop circulation, no three wastes are discharged in the process, the process is green and environmentally friendly, and the addition of raw materials is reduced, and the investment cost and production cost are low.

[0022] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for separating iron and scandium from cobalt-nickel hydroxide raw materials, characterized in that: The method comprises the following preparation steps: (1) crushing and grinding cobalt nickel hydroxide to less than 120 μm; (2) mixing the ground cobalt nickel hydroxide raw material with bottom water at a liquid-to-solid ratio of 1-5:1 and heating to 50-80°C; (3) adjusting the pH of the system to 1.5-3.0 with sulfuric acid, and adding a reducing agent to dissolve all the raw materials; adding a neutralizing agent to the system to adjust the pH, so that the iron and scandium in the system are co-precipitated to form solid slag, followed by solid-liquid separation, and the filtered cobalt-nickel solution directly enters the extraction section, and the separated solid slag is washed with water and then filtered to recover the washing water and solid slag separately for standby use; (4) the washing water is returned to step (2) for cyclic pulping, and the recovered solid residue is re-slurried with water, and then acid and a reducing agent are added to dissolve it again into a mixed solution containing ferrous ions and scandium ions; (5) The mixed solution after dissolution in step (4) is sent into an autoclave, and an appropriate amount of oxygen is introduced to oxidize the iron, and a certain oxygen partial pressure is maintained. The reaction is carried out at a high temperature for 2 to 6 hours, and the iron slag and a relatively pure scandium salt solution are obtained by filtering; (6) adjusting the pH of the scandium salt solution generated in step (5) with a precipitant, reacting for 0.5 to 2.0 hours, and precipitating a scandium-rich slag; (7) The iron slag formed in step (5) is subjected to magnetic separation, rinsing, drying and screening to obtain a finished product.

2. The method for separating iron and scandium from cobalt-nickel hydroxide raw materials according to claim 1, characterized in that: The reducing agent in step (3) is sulfite or hydrogen peroxide solution.

3. The method for separating iron and scandium from cobalt-nickel hydroxide raw materials according to claim 1, characterized in that: The neutralizing agent in step (3) is a cobalt nickel hydroxide raw material and one of sodium carbonate, sodium hydroxide and sodium bicarbonate, and the pH value after neutralization is 3-6.

4. The method for separating iron and scandium from cobalt-nickel hydroxide raw materials according to claim 1, characterized in that: In step (4), the acid is industrial sulfuric acid and the reducing agent is hydrogen peroxide.

5. The method for separating iron and scandium from cobalt-nickel hydroxide raw materials according to claim 1, characterized in that: The oxygen partial pressure in step (5) is 0.1-0.3 MPa, the reaction temperature is 130-180° C., and the main component of the scandium salt solution is scandium sulfate.

6. The method for separating iron and scandium from cobalt-nickel hydroxide raw materials according to claim 1, characterized in that: The precipitating agent in step (6) is one or more of sodium hydroxide, sodium carbonate or sodium oxalate.

7. The method for separating iron and scandium from cobalt-nickel hydroxide raw materials according to claim 1, characterized in that: The pH value of the reaction in step (6) is adjusted to 4-5.

8. The method for separating iron and scandium from cobalt-nickel hydroxide raw materials according to claim 1, characterized in that: The quality of the finished product in step (7) is that the iron oxide content reaches 86.5%, the specific gravity is 5.16, and it meets the first-class product standards.

9. The method for separating iron and scandium from cobalt-nickel hydroxide raw materials according to claim 1, characterized in that: The rinse water generated in step (7) is collected and used as bottom water, and is returned to the system step (2) for use in slurrying with the cobalt nickel hydroxide raw material.

10. The method for separating iron and scandium from cobalt-nickel hydroxide raw materials according to claim 1, characterized in that: The cobalt nickel hydroxide mainly comprises 3.13% Co, 37.13% Ni, 0.12% Cu, 0.37% Fe, 5.23% Mn, 0.52% Zn and 0.06% Sc.

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