A method for removing phosphorus from a cobalt intermediate containing phosphorus

Abstract

The application belongs to the technical field of metallurgical chemical industry, and particularly relates to a method for removing phosphorus from a cobalt intermediate containing phosphorus, which comprises the following steps: mixing and slurrying green vitriol with the cobalt intermediate containing phosphorus, and forming a first slurry after reaction; the cobalt intermediate containing phosphorus comprises Co(OH)3 and phosphate, and the first slurry comprises Fe 3+ ; an excess of sulfuric acid is added to the first slurry to form a second slurry; the pH of the second slurry is adjusted to generate a precipitate, and the precipitate comprises FePO4; and a filter cake and a cobalt-containing solution are obtained by filtration. The application utilizes the oxidizability of Co(OH)3 in the cobalt intermediate containing phosphorus, does not need to introduce an oxidizing agent additionally, and reduces the cost of external reagents; the green vitriol is used in a multifunctional manner, that is, the green vitriol is used as a reducing agent to reduce high-valence cobalt ions to reduce cobalt loss, and the green vitriol is used as an iron source to provide a precipitant to remove phosphorus impurities; and by adjusting the pH, efficient gradient precipitation of phosphorus and iron impurities is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metallurgical chemical engineering, and particularly relates to a method for removing phosphorus from cobalt intermediate products containing phosphorus. BACKGROUND

[0002] Cobalt intermediate products are main metallurgical chemical raw materials for producing Co products. If cobalt intermediate products contain phosphorus impurities such as phosphate and phosphite, it will cause problems such as crystallization of leaching solution, blockage of system pipeline, and excessive phosphorus in products. The existing phosphorus removal technology focuses on nickel-cobalt metallurgical wastewater treatment, and there is still a lack of systematic research on the removal of phosphorus from cobalt intermediate product leaching solution. SUMMARY

[0003] During transportation or storage, part of Co(OH)2 in the cobalt intermediate product is oxidized to Co(OH)3 in the air, and the trivalent cobalt ion in Co(OH)3 has oxidizing property and can oxidize Fe 2+ without introducing an additional oxidizing agent. The present application utilizes this property of Co(OH)3 and provides a method for removing phosphorus from cobalt intermediate products containing phosphorus. The cobalt intermediate product containing phosphorus is mixed with copperas (FeSO4·7H2O) and slurried, sulfuric acid is added for leaching, and the pH is adjusted to selectively precipitate FePO4, thereby removing phosphorus. Compared with traditional aluminum salts, FeSO4 in the present application has three functions of reducing sulfuric acid consumption, reducing high valence Co ions, and removing phosphorus, has the advantages of low cost and high stability of precipitate, and residual control is simple and has no effect on subsequent extraction process.

[0004] The method for removing phosphorus from cobalt intermediate products containing phosphorus provided by the present application comprises the following steps:

[0005] S1, mixing copperas with cobalt intermediate product containing phosphorus and slurrying, and forming first slurry after reaction; the cobalt intermediate product containing phosphorus comprises Co(OH)3 and phosphate, and the first slurry comprises Fe 3+ ;

[0006] S2, adding excess sulfuric acid to the first slurry to form second slurry;

[0007] S3, adjusting the pH of the second slurry to generate a precipitate, the precipitate comprising FePO4, and filtering to obtain filter cake and cobalt-containing solution.

[0008] In the above technical solution, in step S1, copperas is mixed with cobalt intermediate product containing phosphorus and slurried, and after copperas dissolves, Fe 2+ , which is oxidized to Fe 2+ , and the trivalent cobalt in Co(OH)3 is reduced to Co 3+ which can exist stably in solution. 2+, reduce cobalt loss; in step S2, excess sulfuric acid is added to the first slurry to make the solution strongly acidic, converting cobalt hydroxide into soluble cobalt salt such as cobalt sulfate, releasing bound phosphorus, both phosphorus and cobalt being fully leached into the solution, at this time the solution contains molecules or ions including H3PO4, H2PO4 － , HPO4 2－ , PO4 3－ , SO4 2－ , Fe 3+ , Co 2+ ; in step S3, the pH of the second slurry is adjusted to make the solution pH rise, Fe 3+ reacts with H3PO4, H2PO4 － , HPO4 2－ , PO4 3－ to generate FePO4 precipitate, which can be removed by filtration.

[0009] As a preferred scheme of the method for removing phosphorus from a phosphorus-containing cobalt intermediate product of the present application, in step S3, the pH of the second slurry is adjusted to 2.5-4.5 to generate a first precipitate, and then the pH of the second slurry is further adjusted to 4.5-5.5 to generate a second precipitate, and a filter cake and a cobalt-containing solution are obtained by filtration; the first precipitate includes FePO4, and the second precipitate includes Fe(OH)3; in this scheme, the pH adjustment of the second slurry is in two stages, the initial adjustment of the pH to 2.5-4.5 is to make Fe 3+ react with P fully to precipitate FePO4, achieving the purpose of removing phosphorus; if the solution still contains excess Fe 3+ , Fe 3+ will also gradually hydrolyze to precipitate Fe(OH)3 during this process; the later adjustment of the pH to 4.5-5.5 is to make the excess Fe 3+ further hydrolyze to precipitate Fe(OH)3, achieving the purpose of deep iron removal.

[0010] As a preferred scheme of the method for removing phosphorus from a phosphorus-containing cobalt intermediate product of the present application, after step S3, the method further includes: washing the filter cake with an acid solution to obtain a filter cake washed with a filtrate, and returning the filtrate to step S1 for slurry adjustment; in this scheme, the filter cake is washed with an acid solution to wash the cobalt ions entrained in the filter cake into the filtrate, and the filtrate is returned to step S1 for slurry adjustment, which can recover the washed cobalt ions and reduce the acid consumption during leaching.

[0011] As a preferred scheme of the method for removing phosphorus from a phosphorus-containing cobalt intermediate product of the present application, the content of Co(OH)3 in the phosphorus-containing cobalt intermediate product is 0.1wt%-3.25wt%, and the content of phosphate in the phosphorus-containing cobalt intermediate product, calculated as phosphorus element, is 0.1wt%-5.0wt%.

[0012] As a preferred embodiment of the method for removing phosphorus from a phosphorus-containing cobalt intermediate of the present application, the mass ratio of green vitriol to the phosphorus-containing cobalt intermediate is 1:20~1:5; the phosphorus-containing cobalt intermediate may also contain metal elements such as Ca and Al, which can also form phosphate precipitates to remove phosphorus. Therefore, the amount of green vitriol can be appropriately adjusted according to the composition of the phosphorus-containing cobalt intermediate.

[0013] As a preferred embodiment of the method for removing phosphorus from a phosphorus-containing cobalt intermediate product of the present application, in step S1, the liquid-solid ratio is 3:1-5:1, the reaction temperature is 20-80°C, and the reaction time is 30-60 min.

[0014] As a preferred embodiment of the method for removing phosphorus from a phosphorus-containing cobalt intermediate product of the present application, in step S2, the reaction temperature is 60-80°C, the reaction time is 1-3 hours, the concentration of sulfuric acid is 10wt%-98wt%, and the pH of the second slurry is 1-1.5.

[0015] As a preferred embodiment of the method for removing phosphorus from a phosphorus-containing cobalt intermediate of the present application, in step S3, an alkaline reagent is used to adjust the pH, and the reaction temperature is 40-60°C; the alkaline reagent includes at least one of CaCO3 slurry or Na2CO3 solution; the concentration of the CaCO3 slurry or Na2CO3 solution is 5wt%-20wt%.

[0016] As a preferred embodiment of the method for removing phosphorus from a phosphorus-containing cobalt intermediate product of the present application, the acid solution is dilute sulfuric acid; the pH of the dilute sulfuric acid is 2.0-3.0, and the pH of the filtrate is 2.0-3.5.

[0017] As a preferred embodiment of the method for removing phosphorus from a phosphorus-containing cobalt intermediate product of the present application, the concentration of phosphorus in the cobalt-containing solution is less than 0.01 g / L, and the concentration of iron is less than 0.01 g / L.

[0018] The present application proposes a method for removing phosphorus from a phosphorus-containing cobalt intermediate, which has the following beneficial effects: utilizing the oxidizing property of Co(OH)3 in the phosphorus-containing cobalt intermediate, there is no need to introduce additional oxidants, thereby reducing the cost of external reagents; realizing the multifunctional utilization of green vitriol, which acts as a reducing agent to reduce high-valent cobalt ions to reduce cobalt loss, and as an iron source to provide a precipitant to remove phosphorus impurities; and by adjusting the pH, efficient gradient precipitation of phosphorus and iron impurities is achieved. DETAILED DESCRIPTION

[0019] The following will be a clear and complete description of the technical solutions in the embodiments. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0020] The technical scheme provided in the application comprises the following steps:

[0021] S1, mix green vitriol with phosphorus-containing cobalt intermediate product and adjust the slurry, and form a first slurry after reaction; the phosphorus-containing cobalt intermediate product comprises Co(OH)3 and phosphate, and the first slurry comprises Fe 3+ ;

[0022] Specifically, the green vitriol is uniformly mixed with the phosphorus-containing cobalt intermediate product comprising Co(OH)3 and phosphate, and the slurry is adjusted, the liquid-solid ratio is controlled to be 3:1-5:1, and the reaction is carried out at a reaction temperature of 20-80℃ and a stirring speed of 150-300rpm for 30-60min to form a first slurry; the content of Co(OH)3 in the phosphorus-containing cobalt intermediate product is 0.1wt%-3.25wt%, the content of phosphate in the phosphorus-containing cobalt intermediate product is 0.1wt%-5.0wt% in terms of phosphorus element, and the mass ratio of green vitriol to phosphorus-containing cobalt intermediate product is 1:20-1:5; specifically, the reaction temperature is any one of 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃ or a range between any two of them, the reaction time is any one of 30min, 40min, 50min, 60min or a range between any two of them, the content of Co(OH)3 in the phosphorus-containing cobalt intermediate product is any one of 0.1wt%, 0.5wt%, 1.0wt%, 1.5wt%, 2.0wt% or a range between any two of them, the content of phosphate is any one of 0.1wt%, 1.0wt%, 2.0wt%, 3.0wt%, 4.0wt%, 5.0wt% or a range between any two of them in terms of phosphorus element, and the mass ratio of green vitriol to phosphorus-containing cobalt intermediate product is any one of 1:20, 1:15, 1:10, 1:8, 1:5 or a range between any two of them.

[0023] S2, add excess sulfuric acid to the first slurry to form a second slurry;

[0024] Specifically, excess sulfuric acid with a concentration of 10%-98% is added to the first slurry, and the reaction is carried out at a reaction temperature of 60-80℃ for 1-3h to form a second slurry with a pH of 1-1.5; specifically, the concentration of sulfuric acid is any one of 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, 98wt% or a range between any two of them, the reaction temperature is any one of 60℃, 65℃, 70℃, 75℃, 80℃ or a range between any two of them, and the reaction time is any one of 1h, 1.5h, 2h, 2.5h, 3h or a range between any two of them.

[0025] S3, adjust the pH of the second slurry to generate a precipitate, and the precipitate comprises FePO4; the filter cake and the cobalt-containing solution are obtained by filtration.

[0026] Specifically, the pH of the second slurry is adjusted to 2.5-4.5 using a basic reagent at a reaction temperature of 40-60°C to generate a first precipitate, and then the pH is further adjusted to 4.5-5.5 to generate a second precipitate, and a filter cake and a cobalt-containing solution are obtained by filtration; the first precipitate comprises FePO4, and the second precipitate comprises Fe(OH)3; the basic reagent comprises at least one of CaCO3 slurry or Na2CO3 solution; the concentration of the CaCO3 slurry or the Na2CO3 solution is any one of 5wt%-20wt% or within a range between any two of them; then the filter cake is washed with dilute sulfuric acid having a pH of 2.0-3.0 to obtain a filtrate and a washed filter cake, and the filtrate is returned to step S1 for slurry adjustment; specifically, the reaction temperature is any one of 40°C, 45°C, 50°C, 55°C, 60°C or within a range between any two of them, the concentration of the CaCO3 slurry and / or the Na2CO3 solution is 5wt%, 10wt%, 15wt%, 20wt%, the pH of the solution is any one of 2.5, 3.0, 3.5, 4.0, 4.5 or within a range between any two of them when the first precipitate is generated, and the pH of the solution is any one of 4.5, 4.8, 5.0, 5.3, 5.5 or within a range between any two of them when the second precipitate is generated.

[0027] The technical solutions of the present application are further described below in combination with specific embodiments.

[0028] Embodiment 1

[0029] In this example, the content of Co(OH)3 is 1.05wt%, and the content of phosphate is 1.16wt% in terms of phosphorus element. The green vitriol and the phosphorus-containing cobalt intermediate product are mixed uniformly and adjusted to a slurry, the mass ratio of the green vitriol to the phosphorus-containing cobalt intermediate product is 1:10, the liquid-solid ratio is controlled to be 5:1, and the first slurry is formed under the conditions of a reaction temperature of 20°C and a stirring speed of 300rpm for 60min; an excess amount of sulfuric acid with a concentration of 98% is added to the first slurry, and the second slurry is formed under the condition of a reaction temperature of 60°C for 3h; the pH of the second slurry is adjusted to 4.5 at a reaction temperature of 60°C to generate a precipitate, and a filter cake and a cobalt-containing solution are obtained by filtration; the filter cake is washed with dilute sulfuric acid having a pH of 3.0 to obtain a filtrate and a washed filter cake.

[0030] It is detected that the concentration of phosphorus element in the cobalt-containing solution is 0.009g / L, the concentration of iron element is 0.006g / L, and the content of Co in the washed filter cake is 0.06%.

[0031] Embodiment 2

[0032] In this case, the content of Co(OH)3 is 1.05wt%, and the content of phosphate is 1.16wt% in terms of phosphorus element. The green vitriol and the cobalt intermediate product containing phosphorus are mixed uniformly and slurried, the mass ratio of the green vitriol to the cobalt intermediate product containing phosphorus is 1:5, the liquid-solid ratio is controlled to be 3:1, and the first slurry is formed under the conditions that the reaction temperature is 20℃ and the stirring speed is 300rpm for 60min; an excess of sulfuric acid with a concentration of 20% is added to the first slurry, and the second slurry is formed under the condition that the reaction temperature is 80℃ for 3h; the pH of the second slurry is adjusted to 4.5 at a reaction temperature of 60℃, a precipitate is generated, and a filter cake and a cobalt-containing solution are obtained by filtration; the filter cake is washed with dilute sulfuric acid with a pH of 2.0 to obtain a filtrate and a washed filter cake.

[0033] It is detected that the concentration of phosphorus element in the cobalt-containing solution is 0.004g / L, the concentration of iron element is 0.006g / L, and the content of Co in the washed filter cake is 0.02%.

[0034] Example 3

[0035] In this case, the content of Co(OH)3 is 1.05wt%, and the content of phosphate is 1.16wt% in terms of phosphorus element. The green vitriol and the cobalt intermediate product containing phosphorus are mixed uniformly and slurried, the mass ratio of the green vitriol to the cobalt intermediate product containing phosphorus is 1:10, the liquid-solid ratio is controlled to be 5:1, and the first slurry is formed under the conditions that the reaction temperature is 80℃ and the stirring speed is 150rpm for 30min; an excess of sulfuric acid with a concentration of 10% is added to the first slurry, and the second slurry is formed under the condition that the reaction temperature is 60℃ for 2h; the pH of the second slurry is adjusted to 2.5 at a reaction temperature of 40℃, a first precipitate is generated, the pH of the second slurry is further adjusted to 5.5, a second precipitate is generated, and a filter cake and a cobalt-containing solution are obtained by filtration; the first precipitate comprises FePO4, and the second precipitate comprises Fe(OH)3; the filter cake is washed with dilute sulfuric acid with a pH of 3.0 to obtain a filtrate and a washed filter cake.

[0036] It is detected that the concentration of phosphorus element in the cobalt-containing solution is 0.001g / L, the concentration of iron element is 0.003g / L, and the content of Co in the washed filter cake is 0.01%.

[0037] Example 4

[0038] In this case, the content of Co(OH)3 is 3.25wt%, and the content of phosphate is 0.51wt% in terms of phosphorus element. The green vitriol and the cobalt intermediate product containing phosphorus are mixed uniformly and slurried, the mass ratio of the green vitriol to the cobalt intermediate product containing phosphorus is 1:20, the liquid-solid ratio is controlled to be 4:1, the reaction is carried out at a reaction temperature of 50℃ and a stirring speed of 200rpm for 45min to form a first slurry; an excess of sulfuric acid with a concentration of 98% is added to the first slurry, and the reaction is carried out at a reaction temperature of 70℃ for 1h to form a second slurry; the pH of the second slurry is adjusted to 2.5 at a reaction temperature of 50℃ to generate a precipitate, and a filter cake and a cobalt-containing solution are obtained by filtration; the filter cake is washed with dilute sulfuric acid with a pH of 3.0 to obtain a filtrate and a washed filter cake.

[0039] It is detected that the concentration of phosphorus element in the cobalt-containing solution is 0.004g / L, the concentration of iron element is 0.016g / L, and the content of Co in the washed filter cake is 0.03%.

[0040] Example 5

[0041] In this case, the content of Co(OH)3 is 3.25wt%, and the content of phosphate is 0.51wt% in terms of phosphorus element. The green vitriol and the cobalt intermediate product containing phosphorus are mixed uniformly and slurried, the mass ratio of the green vitriol to the cobalt intermediate product containing phosphorus is 1:20, the liquid-solid ratio is controlled to be 4:1, the reaction is carried out at a reaction temperature of 50℃ and a stirring speed of 200rpm for 45min to form a first slurry; an excess of sulfuric acid with a concentration of 98% is added to the first slurry, and the reaction is carried out at a reaction temperature of 70℃ for 1h to form a second slurry; the pH of the second slurry is adjusted to 2.5 at a reaction temperature of 50℃ to generate a precipitate, and a filter cake and a cobalt-containing solution are obtained by filtration; the filter cake is washed with dilute sulfuric acid with a pH of 3.0 to obtain a filtrate and a washed filter cake.

[0042] It is detected that the concentration of phosphorus element in the cobalt-containing solution is 0.004g / L, the concentration of iron element is 0.005g / L, and the content of Co in the washed filter cake is 0.03%.

[0043] Example 6

[0044] In this case, the content of Co(OH)3 is 3.25wt%, and the content of phosphate is 0.51wt% in terms of phosphorus element. The green vitriol and the phosphorus-containing cobalt intermediate product are mixed uniformly and slurried, and the mass ratio of the green vitriol to the phosphorus-containing cobalt intermediate product is 1:20. The liquid-solid ratio is controlled to be 5:1, and the reaction is carried out at a reaction temperature of 20℃ and a stirring speed of 300rpm for 60min to form a first slurry; an excess of sulfuric acid with a concentration of 98% is added to the first slurry, and the reaction is carried out at a reaction temperature of 80℃ for 3h to form a second slurry; the pH of the second slurry is adjusted to 4.5 at a reaction temperature of 60℃ to generate a precipitate, and the precipitate is filtered to obtain a filter cake and a cobalt-containing solution; the filter cake is washed with dilute sulfuric acid with a pH of 2.0 to obtain a filtrate and a washed filter cake.

[0045] It is detected that the concentration of phosphorus element in the cobalt-containing solution is 0.006g / L, and the concentration of iron element is 0.003g / L. The content of Co in the washed filter cake is 0.01%.

[0046] Example 7

[0047] In this case, the content of Co(OH)3 is 3.25wt%, and the content of phosphate is 0.51wt% in terms of phosphorus element. The green vitriol and the phosphorus-containing cobalt intermediate product are mixed uniformly and slurried, and the mass ratio of the green vitriol to the phosphorus-containing cobalt intermediate product is 1:20. The liquid-solid ratio is controlled to be 5:1, and the reaction is carried out at a reaction temperature of 20℃ and a stirring speed of 300rpm for 60min to form a first slurry; an excess of sulfuric acid with a concentration of 98% is added to the first slurry, and the reaction is carried out at a reaction temperature of 60℃ for 3h to form a second slurry; the pH of the second slurry is adjusted to 4.5 at a reaction temperature of 60℃ to generate a precipitate, and the precipitate is filtered to obtain a filter cake and a cobalt-containing solution; the filter cake is washed with dilute sulfuric acid with a pH of 2.0 to obtain a filtrate and a washed filter cake.

[0048] It is detected that the concentration of phosphorus element in the cobalt-containing solution is 0.006g / L, and the concentration of iron element is 0.003g / L. The content of Co in the washed filter cake is 0.01%.

[0049] Comparative Example 1

[0050] In this case, the content of Co(OH)3 is 1.05wt%, and the content of phosphate is 1.16wt% in terms of phosphorus element. The phosphorus-containing cobalt intermediate product is slurried with water, and the liquid-solid ratio is controlled to be 5:1. The reaction is carried out at a reaction temperature of 20℃ and a stirring speed of 300rpm for 60min to form a first slurry; an excess of sulfuric acid with a concentration of 98% is added to the first slurry, and the reaction is carried out at a reaction temperature of 60℃ for 4h to form a second slurry; the pH of the second slurry is adjusted to 4.5 at a reaction temperature of 60℃ to generate a precipitate, and the precipitate is filtered to obtain a filter cake and a cobalt-containing solution; the filter cake is washed with dilute sulfuric acid with a pH of 3.0 to obtain a filtrate and a washed filter cake.

[0051] The concentration of phosphorus element in the cobalt-containing solution was 0.97 g / L, and the concentration of iron element was 0.001 g / L. The Co content in the washed filter cake was 0.07%.

[0052] Comparative Example 2

[0053] In this case, the content of Co(OH)3was 1.05 wt%, and the content of phosphate was 1.16 wt% in terms of phosphorus element. The copperas and the cobalt-containing intermediate product containing phosphorus were mixed uniformly and slurried. The mass ratio of the copperas to the cobalt-containing intermediate product containing phosphorus was 1:5, and the liquid-solid ratio was controlled to be 5:1. The first slurry was formed under the conditions of a reaction temperature of 20°C and a stirring speed of 300 rpm for 60 min. Excessive sulfuric acid with a concentration of 98% was added to the first slurry, and the second slurry was formed under the conditions of a reaction temperature of 60°C for 3 h. The filter cake and the cobalt-containing solution were obtained by filtration. The filter cake was washed with dilute sulfuric acid with a pH of 3.0 to obtain the filtrate and the washed filter cake.

[0054] The concentration of phosphorus element in the cobalt-containing solution was 0.012 g / L, and the concentration of iron element was 0.63 g / L. The Co content in the washed filter cake was 0.04%.

[0055] Comparative Example 3

[0056] In this case, the content of Co(OH)3was 1.05 wt%, and the content of phosphate was 1.16 wt% in terms of phosphorus element. The cobalt-containing intermediate product containing phosphorus was slurried with water, and the liquid-solid ratio was controlled to be 5:1. Excessive sulfuric acid with a concentration of 98% was added, and the first slurry was formed under the conditions of a reaction temperature of 60°C for 3 h. The copperas was added to the first slurry under the conditions of a reaction temperature of 20°C for 60 min. The mass ratio of the copperas to the cobalt-containing intermediate product containing phosphorus was 1:10. The pH of the second slurry was adjusted to 4.5 under the conditions of a reaction temperature of 60°C to generate a precipitate. The filter cake and the cobalt-containing solution were obtained by filtration. The filter cake was washed with dilute sulfuric acid with a pH of 3.0 to obtain the filtrate and the washed filter cake.

[0057] The concentration of phosphorus element in the cobalt-containing solution was 0.012 g / L, and the concentration of iron element was 0.63 g / L. The Co content in the washed filter cake was 0.04%.

[0058] The parameters of the cobalt-containing solution and the washed filter cake obtained in each example and comparative example are shown in Table 1.

[0059] Table 1

[0060]

[0061] From the above examples and comparative examples, it can be seen that by using the technical solution of the present application, only green vitriol is used, no additional oxidizing agent is introduced, and by sulfuric acid leaching and adjusting pH, the removal of phosphorus in the phosphorus-containing cobalt intermediate product can be realized, and the impurity iron is precipitated; by using an acid solution to wash the filter cake, cobalt can be recovered, and the cobalt loss rate is less than 0.1%.

[0062] The method for removing phosphorus from a phosphorus-containing cobalt intermediate product provided by the present application has the following beneficial effects: the oxidizing property of Co(OH)3 in the phosphorus-containing cobalt intermediate is utilized, no additional oxidizing agent is introduced, and the cost of external reagents is reduced; the multifunctional use of green vitriol is realized, that is, green vitriol is used as a reducing agent to reduce high-valence cobalt ions to reduce cobalt loss and as an iron source to provide a precipitant to remove phosphorus impurities; by adjusting pH, efficient gradient precipitation of phosphorus and iron impurities is realized.

[0063] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structural transformation made by using the content of the present application specification, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A method for removing phosphorus from a phosphorus-containing cobalt intermediate, characterized in that: The following steps are involved: S1, mixing green vitriol and phosphorus-containing cobalt intermediate and slurrying, forming a first slurry after reaction; the phosphorus-containing cobalt intermediate includes Co(OH)3 and phosphate, the content of Co(OH)3 in the phosphorus-containing cobalt intermediate is 0.1wt%~3.25wt%, and the green vitriol releases Fe after dissolution. 2+ , undergoes redox reaction with the Co(OH)3, Fe 2+ Oxidized to Fe 3+ , the trivalent cobalt in Co(OH)3 is reduced to Co 2+ Without introducing an additional oxidant, the first slurry includes Fe 3+ ; S2. Adding excess sulfuric acid to the first slurry to form a second slurry, wherein the pH of the second slurry is 1 to 1.5; S3. Adjust the pH of the second slurry to 2.5-4.5 to generate a first precipitate, further adjust the pH of the second slurry to 4.5-5.5 to generate a second precipitate, and filter to obtain a filter cake and a cobalt-containing solution; the first precipitate includes FePO4, and the second precipitate includes Fe(OH)3.

2. The method for removing phosphorus from a phosphorus-containing cobalt intermediate according to claim 1, characterized in that: After step S3, the method further includes: washing the filter cake with an acid solution to obtain a filtrate and a washed filter cake, and returning the filtrate to step S1 for slurry preparation.

3. The method for removing phosphorus from a phosphorus-containing cobalt intermediate according to claim 1, characterized in that: The content of phosphate in the phosphorus-containing cobalt intermediate is 0.1 wt% to 5.0 wt% in terms of phosphorus element.

4. The method for removing phosphorus from a phosphorus-containing cobalt intermediate according to claim 3, characterized in that: The mass ratio of the green vitriol to the phosphorus-containing cobalt intermediate is 1:20 to 1:

5.

5. The method for removing phosphorus from a phosphorus-containing cobalt intermediate according to claim 1, characterized in that: In step S1, the liquid-solid ratio is 3:1-5:1, the reaction temperature is 20-80° C., and the reaction time is 30-60 min.

6. The method for removing phosphorus from a phosphorus-containing cobalt intermediate according to claim 1, characterized in that: In step S2, the reaction temperature is 60-80° C., the reaction time is 1-3 hours, and the concentration of the sulfuric acid is 10 wt %-98 wt %.

7. The method for removing phosphorus from a phosphorus-containing cobalt intermediate according to claim 1, characterized in that: In step S3, an alkaline reagent is used to adjust the pH, and the reaction temperature is 40-60° C.; the alkaline reagent includes at least one of CaCO 3 slurry or Na 2 CO 3 solution; the concentration of the CaCO 3 slurry or the Na 2 CO 3 solution is 5 wt %-20 wt %.

8. The method for removing phosphorus from a phosphorus-containing cobalt intermediate according to claim 2, characterized in that: The acid solution is dilute sulfuric acid; the pH of the dilute sulfuric acid is 2.0-3.0, and the pH of the filtrate is 2.0-3.

5.

9. The method for removing phosphorus from a phosphorus-containing cobalt intermediate according to claim 1, characterized in that: The concentration of phosphorus in the cobalt-containing solution is less than 0.01 g / L, and the concentration of iron in the cobalt-containing solution is less than 0.01 g / L.

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