Method for removing phosphorus from intermediate product containing phosphorus and cobalt

Abstract

The invention belongs to the technical field of metallurgy and chemical industry, and particularly relates to a phosphorus removal method for a phosphorus-cobalt-containing intermediate product, which comprises the following steps: mixing copperas and the phosphorus-cobalt-containing intermediate product, carrying out size mixing, and reacting to form first size; the phosphorus-containing cobalt intermediate product comprises Co (OH) 3 and phosphate, and the first slurry comprises Fe < 3 + >; adding excessive sulfuric acid into the first slurry to form second slurry; and adjusting the pH value of the second slurry to generate a precipitate which comprises FePO4, and filtering to obtain a filter cake and a cobalt-containing solution. According to the method, the oxidizability of Co (OH) 3 in the phosphorus-containing cobalt intermediate is utilized, an oxidizing agent does not need to be additionally introduced, and the cost of an external reagent is reduced; the copperas can be used as a reducing agent to reduce high-valence cobalt ions so as to reduce cobalt loss, and can also be used as an iron source to provide a precipitator to remove phosphorus impurities; by adjusting the pH value, efficient gradient precipitation of phosphorus and iron impurities is realized.

Description

Technical Field

[0001] This application belongs to the technical field of metallurgical chemistry, and specifically relates to a method for removing phosphorus from phosphorus-containing cobalt intermediate products. Background Art

[0002] Cobalt intermediate products are the main metallurgical chemical raw materials for the production of Co products. If phosphorus-containing impurities such as phosphate ions and phosphite ions are present in cobalt intermediate products, it will cause problems such as crystallization in the leaching solution, blockage of the system pipeline, and excessive phosphorus content in the product. In existing processes, the phosphorus removal technology mostly focuses on the treatment of nickel-cobalt metallurgical wastewater, and there is still a lack of systematic research on the method for removing phosphorus from the leaching solution of cobalt intermediate products. Summary of the Invention

[0003] During the transportation or storage of cobalt intermediate products, some of the Co(OH)2 therein will be oxidized to Co(OH)3 in the air, and the trivalent cobalt ions in Co(OH)3 have oxidizing properties and can oxidize Fe 2+ without the need to additionally introduce an oxidizing agent. This application utilizes this property of Co(OH)3 to provide a method for removing phosphorus from phosphorus-containing cobalt intermediate products. The phosphorus-containing cobalt intermediate product is mixed with ferrous sulfate heptahydrate (FeSO4·7H2O) to form a slurry, sulfuric acid is added for leaching, and then the pH is adjusted to selectively precipitate FePO4 to achieve phosphorus removal. Compared with traditional aluminum salts, FeSO4 in this application has three functions: reducing sulfuric acid consumption, reducing high-valent Co ions, and removing phosphorus. It has the advantages of low cost, high stability of the precipitate, simple residue control, and no impact on subsequent processes such as extraction.

[0004] The method for removing phosphorus from the phosphorus-containing cobalt intermediate product of this application includes the following steps: S1. Mix ferrous sulfate heptahydrate with the phosphorus-containing cobalt intermediate product and form a slurry. After the reaction, a first slurry is formed. The phosphorus-containing cobalt intermediate product includes Co(OH)3 and phosphate, and the first slurry includes Fe 3+ ; S2. Add excessive sulfuric acid to the first slurry to form a second slurry; S3. Adjust the pH of the second slurry to generate a precipitate. The precipitate includes FePO4, and filter to obtain a filter cake and a cobalt-containing solution.

[0005] In the above technical solution, in step S1, ferrous sulfate heptahydrate is mixed with the phosphorus-containing cobalt intermediate product and formed into a slurry. After ferrous sulfate heptahydrate is dissolved, it releases Fe 2+ , and an oxidation-reduction reaction occurs with Co(OH)3. Fe 2+ is oxidized to Fe 3+ , while the trivalent cobalt in Co(OH)3 is reduced to Co that can stably exist in the solution 2+, reducing cobalt loss; in step S2, an excessive amount of sulfuric acid is added to the first slurry to make the solution strongly acidic, converting cobalt hydroxide into a soluble cobalt salt such as cobalt sulfate and releasing bound phosphorus. Both phosphorus and cobalt are 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 increase the pH of the solution. Fe 3+ will react with H3PO4, H2PO4 － , HPO4 2－ , PO4 3－ to form FePO4 precipitate, and FePO4 can be removed by filtration.

[0006] As a preferred embodiment 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 form a first precipitate, and further adjusted to 4.5 - 5.5 to form a second precipitate. The filter cake and cobalt-containing solution are obtained by filtration; the first precipitate includes FePO4, and the second precipitate includes Fe(OH)3; in this embodiment, the pH control of the second slurry is divided into two stages. Adjusting the pH to 2.5 - 4.5 initially is to make Fe 3+ react fully with P to precipitate FePO4 and achieve the purpose of phosphorus removal; if there is still excessive Fe 3+ in the solution, Fe 3+ will also gradually hydrolyze and precipitate Fe(OH)3 during this process; adjusting the pH to 4.5 - 5.5 later is to further hydrolyze the excessive Fe 3+ into Fe(OH)3 precipitate to achieve the purpose of deep iron removal.

[0007] As a preferred embodiment of the method for removing phosphorus from a phosphorus-containing cobalt intermediate product of the present application, after step S3, it further includes: washing the filter cake with an acid solution to obtain a washed filter cake and a filtrate, and returning the filtrate to step S1 for slurry adjustment; in this embodiment, washing the filter cake with an acid solution can wash out the cobalt ions entrained in the filter cake into the filtrate, and returning the filtrate to step S1 for slurry adjustment can, on the one hand, recover the washed-out cobalt ions and, on the other hand, reduce the acid consumption during leaching.

[0008] As a preferred embodiment 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 0.1 wt% - 3.25 wt%, and the content of phosphate in the phosphorus-containing cobalt intermediate product is 0.1 wt% - 5.0 wt% in terms of phosphorus element.

[0009] As a preferred embodiment of the method for removing phosphorus from the phosphorus-containing cobalt intermediate product of the present application, the mass ratio of ferrous sulfate heptahydrate to the phosphorus-containing cobalt intermediate product is 1:20 to 1:5; the phosphorus-containing cobalt intermediate product may also contain metal elements such as Ca and Al, and these metal elements can also form phosphate precipitates to remove phosphorus. Therefore, the dosage of ferrous sulfate heptahydrate can be appropriately adjusted according to the composition of the phosphorus-containing cobalt intermediate product.

[0010] As a preferred embodiment of the method for removing phosphorus from the phosphorus-containing cobalt intermediate product of the present application, in step S1, the liquid-solid ratio is 3:1 to 5:1, the reaction temperature is 20 to 80 °C, and the reaction time is 30 to 60 min.

[0011] As a preferred embodiment of the method for removing phosphorus from the phosphorus-containing cobalt intermediate product of the present application, in step S2, the reaction temperature is 60 to 80 °C, the reaction time is 1 to 3 h; the concentration of sulfuric acid is 10 wt% to 98 wt%, and the pH of the second slurry is 1 to 1.5.

[0012] As a preferred embodiment of the method for removing phosphorus from the phosphorus-containing cobalt intermediate product of the present application, in step S3, an alkaline reagent is used to adjust the pH, and the reaction temperature is 40 to 60 °C; the alkaline reagent includes at least one of a CaCO3 slurry or a Na2CO3 solution; the concentration of the CaCO3 slurry or the Na2CO3 solution is 5 wt% to 20 wt%.

[0013] As a preferred embodiment of the method for removing phosphorus from the 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 to 3.0, and the pH of the filtrate is 2.0 to 3.5.

[0014] As a preferred embodiment of the method for removing phosphorus from the phosphorus-containing cobalt intermediate product of the present application, the concentration of phosphorus element in the cobalt-containing solution is less than 0.01 g / L, and the concentration of iron element is less than 0.01 g / L.

[0015] The method for removing phosphorus from the phosphorus-containing cobalt intermediate product proposed by the present application has the following beneficial effects: by utilizing the oxidizing property of Co(OH)3 in the phosphorus-containing cobalt intermediate, no additional oxidant needs to be introduced, reducing the cost of external reagents; realizing the multi-functional utilization of ferrous sulfate heptahydrate, which acts both 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 achieving the efficient gradient precipitation of phosphorus and iron impurities by adjusting the pH. Specific Embodiments

[0016] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0017] The technical solution proposed in this application includes the following steps: S1. Mix ferrous sulfate heptahydrate with a phosphorus-containing cobalt intermediate product and make a slurry. After reaction, a first slurry is formed. The phosphorus-containing cobalt intermediate product includes Co(OH)3 and phosphate. The first slurry includes Fe 3+ ; Specifically, mix ferrous sulfate heptahydrate with a phosphorus-containing cobalt intermediate product including Co(OH)3 and phosphate evenly and make a slurry. Control the liquid-solid ratio to be 3:1 to 5:1. React for 30 to 60 minutes at a reaction temperature of 20 to 80 °C and a stirring speed of 150 to 300 rpm to form a first slurry. The content of Co(OH)3 in the phosphorus-containing cobalt intermediate product is 0.1 wt% to 3.25 wt%. The content of phosphate in the phosphorus-containing cobalt intermediate product is 0.1 wt% to 5.0 wt% in terms of phosphorus element. The mass ratio of ferrous sulfate heptahydrate to the phosphorus-containing cobalt intermediate product is 1:20 to 1:5. Specifically, the reaction temperature is any one or the range between any two of 20 °C, 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, 80 °C. The reaction time is any one or the range between any two of 30 min, 40 min, 50 min, 60 min. The content of Co(OH)3 in the phosphorus-containing cobalt intermediate product is any one or the range between any two of 0.1 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%. The content of phosphate is any one or the range between any two of 0.1 wt%, 1.0 wt%, 2.0 wt%, 3.0 wt%, 4.0 wt%, 5.0 wt% in terms of phosphorus element. The mass ratio of ferrous sulfate heptahydrate to the phosphorus-containing cobalt intermediate product is any one or the range between any two of 1:20, 1:15, 1:10, 1:8, 1:5.

[0018] S2. Add excessive sulfuric acid to the first slurry to form a second slurry. Specifically, add excessive sulfuric acid with a concentration of 10% to 98% to the first slurry and react at a reaction temperature of 60 to 80 °C for 1 to 3 hours to form a second slurry with a pH of 1 to 1.5. Specifically, the concentration of sulfuric acid is any one or the range between any two of 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, 98 wt%. The reaction temperature is any one or the range between any two of 60 °C, 65 °C, 70 °C, 75 °C, 80 °C. The reaction time is any one or the range between any two of 1 h, 1.5 h, 2 h, 2.5 h, 3 h.

[0019] S3. Adjust the pH of the second slurry to generate a precipitate. The precipitate includes FePO4. Filter to obtain a filter cake and a cobalt-containing solution.

[0020] Specifically, at a reaction temperature of 40 to 60 °C, an alkaline reagent is used to adjust the pH of the second slurry to 2.5 to 4.5 to form a first precipitate, and the pH is further adjusted to 4.5 to 5.5 to form a second precipitate. The filter cake and the cobalt-containing solution are obtained by filtration. The first precipitate includes FePO4, and the second precipitate includes Fe(OH)3. The alkaline reagent includes at least one of a CaCO3 slurry or a Na2CO3 solution. The concentration of the CaCO3 slurry or the Na2CO3 solution is in any range between 5 wt% and 20 wt%. Then, the filter cake is washed with dilute sulfuric acid having a pH of 2.0 to 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 in any range between 40 °C, 45 °C, 50 °C, 55 °C, and 60 °C. The concentration of the CaCO3 slurry and / or the Na2CO3 solution is 5 wt%, 10 wt%, 15 wt%, or 20 wt%. When the first precipitate is formed, the pH value of the solution is in any range between 2.5, 3.0, 3.5, 4.0, and 4.5. When the second precipitate is formed, the pH value of the solution is in any range between 4.5, 4.8, 5.0, 5.3, and 5.5.

[0021] The technical solution of the present application will be further described below in conjunction with specific embodiments.

[0022] Example 1 In this case, the content of Co(OH)3 is 1.05 wt%, and the content of phosphate is 1.16 wt% in terms of phosphorus element. Ferrous sulfate heptahydrate and the phosphorus-containing cobalt intermediate product are mixed evenly and slurried. The mass ratio of ferrous sulfate heptahydrate to the phosphorus-containing cobalt intermediate product is 1:10. The liquid-solid ratio is controlled to be 5:1. The reaction is carried out for 60 min at a reaction temperature of 20 °C and a stirring speed of 300 rpm to form a first slurry. Excessive sulfuric acid with a concentration of 98% is added to the first slurry, and the reaction is carried out for 3 h at a reaction temperature of 60 °C to form a second slurry. At a reaction temperature of 60 °C, the pH of the second slurry is adjusted to 4.5 to form a precipitate, and the filter cake and the 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.

[0023] After detection, the concentration of phosphorus element in the cobalt-containing solution is 0.009 g / L, the concentration of iron element is 0.006 g / L, and the Co content in the washed filter cake is 0.06%.

[0024] Example 2 In this case, the content of Co(OH)3 is 1.05 wt%, and the content of phosphate is 1.16 wt% calculated as phosphorus element. Ferrous sulfate heptahydrate is mixed evenly with the phosphorus-containing cobalt intermediate product and slurried. The mass ratio of ferrous sulfate heptahydrate to the phosphorus-containing cobalt intermediate product is 1:5, and the liquid-solid ratio is controlled to be 3:1. The reaction is carried out for 60 min at a reaction temperature of 20 °C and a stirring speed of 300 rpm to form a first slurry; an excessive amount of sulfuric acid with a concentration of 20% is added to the first slurry, and the reaction is carried out for 3 h at a reaction temperature of 80 °C to form a second slurry; at a reaction temperature of 60 °C, the pH of the second slurry is adjusted to 4.5 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.

[0025] After detection, the concentration of phosphorus element in the cobalt-containing solution is 0.004 g / L, the concentration of iron element is 0.006 g / L, and the Co content in the washed filter cake is 0.02%.

[0026] Example 3 In this case, the content of Co(OH)3 is 1.05 wt%, and the content of phosphate is 1.16 wt% calculated as phosphorus element. Ferrous sulfate heptahydrate is mixed evenly with the phosphorus-containing cobalt intermediate product and slurried. The mass ratio of ferrous sulfate heptahydrate to the phosphorus-containing cobalt intermediate product is 1:10, and the liquid-solid ratio is controlled to be 5:1. The reaction is carried out for 30 min at a reaction temperature of 80 °C and a stirring speed of 150 rpm to form a first slurry; an excessive amount of sulfuric acid with a concentration of 10% is added to the first slurry, and the reaction is carried out for 2 h at a reaction temperature of 60 °C to form a second slurry; at a reaction temperature of 40 °C, the pH of the second slurry is adjusted to 2.5 to generate a first precipitate, and the pH of the second slurry is further adjusted to 5.5 to generate a second precipitate. The precipitate is filtered to obtain a filter cake and a cobalt-containing solution; the first precipitate includes FePO4, and the second precipitate includes 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.

[0027] After detection, the concentration of phosphorus element in the cobalt-containing solution is 0.001 g / L, the concentration of iron element is 0.003 g / L, and the Co content in the washed filter cake is 0.01%.

[0028] Example 4 In this case, the content of Co(OH)3 is 3.25 wt%, and the content of phosphate is 0.51 wt% calculated as phosphorus element. Mix ferrous sulfate heptahydrate and the phosphorus-containing cobalt intermediate product evenly and make a slurry. The mass ratio of ferrous sulfate heptahydrate to the phosphorus-containing cobalt intermediate product is 1:20. Control the liquid-solid ratio to be 4:1. React for 45 minutes at a reaction temperature of 50 °C and a stirring speed of 200 rpm to form the first slurry; add excessive sulfuric acid with a concentration of 98% to the first slurry and react for 1 hour at a reaction temperature of 70 °C to form the second slurry; at a reaction temperature of 50 °C, adjust the pH of the second slurry to 2.5 to generate a precipitate, and filter to obtain a filter cake and a cobalt-containing solution; wash the filter cake with dilute sulfuric acid with a pH of 3.0 to obtain a filtrate and the washed filter cake.

[0029] After detection, the concentration of phosphorus element in the cobalt-containing solution is 0.004 g / L, the concentration of iron element is 0.016 g / L, and the Co content in the washed filter cake is 0.03%.

[0030] Example 5 In this case, the content of Co(OH)3 is 3.25 wt%, and the content of phosphate is 0.51 wt% calculated as phosphorus element. Mix ferrous sulfate heptahydrate and the phosphorus-containing cobalt intermediate product evenly and make a slurry. The mass ratio of ferrous sulfate heptahydrate to the phosphorus-containing cobalt intermediate product is 1:15. Control the liquid-solid ratio to be 5:1. React for 60 minutes at a reaction temperature of 20 °C and a stirring speed of 300 rpm to form the first slurry; add excessive sulfuric acid with a concentration of 98% to the first slurry and react for 3 hours at a reaction temperature of 60 °C to form the second slurry; at a reaction temperature of 60 °C, adjust the pH of the second slurry to 4.5 to generate a precipitate, and filter to obtain a filter cake and a cobalt-containing solution; wash the filter cake with dilute sulfuric acid with a pH of 3.0 to obtain a filtrate and the washed filter cake.

[0031] After detection, the concentration of phosphorus element in the cobalt-containing solution is 0.004 g / L, the concentration of iron element is 0.005 g / L, and the Co content in the washed filter cake is 0.03%.

[0032] Example 6 In this case, the content of Co(OH)3 is 3.25 wt%, and the content of phosphate is 0.51 wt% calculated as phosphorus element. Mix ferrous sulfate heptahydrate and the phosphorus-containing cobalt intermediate product evenly and make a slurry. The mass ratio of ferrous sulfate heptahydrate to the phosphorus-containing cobalt intermediate product is 1:20. Control the liquid-solid ratio to be 5:1. React for 60 minutes at a reaction temperature of 20 °C and a stirring speed of 300 rpm to form the first slurry; add excessive sulfuric acid with a concentration of 98% to the first slurry and react for 3 hours at a reaction temperature of 80 °C to form the second slurry; at a reaction temperature of 60 °C, adjust the pH of the second slurry to 4.5 to generate a precipitate, and filter to obtain a filter cake and a cobalt-containing solution; wash the filter cake with dilute sulfuric acid with a pH of 2.0 to obtain a filtrate and the washed filter cake.

[0033] After detection, the concentration of phosphorus element in the cobalt-containing solution is 0.006 g / L, the concentration of iron element is 0.003 g / L, and the Co content in the washed filter cake is 0.01%.

[0034] Example 7 In this case, the content of Co(OH)3 is 3.25 wt%, and the content of phosphate is 0.51 wt% calculated as phosphorus element. Ferrous sulfate heptahydrate is mixed evenly with the phosphorus-containing cobalt intermediate product and slurried. The mass ratio of ferrous sulfate heptahydrate to the phosphorus-containing cobalt intermediate product is 1:20. The liquid-solid ratio is controlled to be 5:1. The reaction is carried out for 60 min at a reaction temperature of 20 °C and a stirring speed of 300 rpm to form a first slurry; an excessive amount of sulfuric acid with a concentration of 98% is added to the first slurry, and the reaction is carried out for 3 h at a reaction temperature of 60 °C to form a second slurry; at a reaction temperature of 60 °C, the pH of the second slurry is adjusted to 4.5 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 pure water to obtain a filtrate and a washed filter cake.

[0035] After detection, the concentration of phosphorus element in the cobalt-containing solution is 0.004 g / L, the concentration of iron element is 0.005 g / L, and the Co content in the washed filter cake is 0.36%.

[0036] Comparative Example 1 In this case, the content of Co(OH)3 is 1.05 wt%, and the content of phosphate is 1.16 wt% calculated as phosphorus element. The phosphorus-containing cobalt intermediate product is slurried with water. The liquid-solid ratio is controlled to be 5:1. The reaction is carried out for 60 min at a reaction temperature of 20 °C and a stirring speed of 300 rpm to form a first slurry; an excessive amount of sulfuric acid with a concentration of 98% is added to the first slurry, and the reaction is carried out for 4 h at a reaction temperature of 60 °C to form a second slurry; at a reaction temperature of 60 °C, the pH of the second slurry is adjusted to 4.5 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.

[0037] After detection, the concentration of phosphorus element in the cobalt-containing solution is 0.97 g / L, the concentration of iron element is 0.001 g / L, and the Co content in the washed filter cake is 0.07%.

[0038] Comparative Example 2 In this example, the content of Co(OH)3 is 1.05 wt%, and the content of phosphate is 1.16 wt% calculated as phosphorus element. Ferrous sulfate is mixed evenly with the phosphorus-containing cobalt intermediate product and slurried. The mass ratio of ferrous sulfate to the phosphorus-containing cobalt intermediate product is 1:5. The liquid-solid ratio is controlled at 5:1. The reaction is carried out for 60 min at a reaction temperature of 20 °C and a stirring speed of 300 rpm to form the first slurry; an excessive amount of sulfuric acid with a concentration of 98% is added to the first slurry, and the reaction is carried out for 3 h at a reaction temperature of 60 °C to form the second slurry; the filter cake and the cobalt-containing solution are obtained by filtration; the filter cake is washed with dilute sulfuric acid with a pH of 3.0 to obtain the filtrate and the washed filter cake.

[0039] After detection, the concentration of phosphorus element in the cobalt-containing solution is 0.012 g / L, the concentration of iron element is 0.63 g / L, and the Co content in the washed filter cake is 0.04%.

[0040] Comparative Example 3 In this example, the content of Co(OH)3 is 1.05 wt%, and the content of phosphate is 1.16 wt% calculated as phosphorus element. The phosphorus-containing cobalt intermediate product is slurried with water. The liquid-solid ratio is controlled at 5:1. An excessive amount of sulfuric acid with a concentration of 98% is added, and the reaction is carried out for 3 h at a reaction temperature of 60 °C to form the first slurry; the reaction temperature is controlled at 20 °C, and ferrous sulfate is added to the first slurry and reacted for 60 min. The mass ratio of ferrous sulfate to the phosphorus-containing cobalt intermediate product is 1:10; at a reaction temperature of 60 °C, the pH of the second slurry is adjusted to 4.5 to generate a precipitate, and the filter cake and the cobalt-containing solution are obtained by filtration; the filter cake is washed with dilute sulfuric acid with a pH of 3.0 to obtain the filtrate and the washed filter cake.

[0041] After detection, the concentration of phosphorus element in the cobalt-containing solution is 0.26 g / L, the concentration of iron element is 0.006 / L, and the Co content in the washed filter cake is 0.05%.

[0042] The parameters of the cobalt-containing solution and the washed filter cake obtained in each example and comparative example are shown in Table 1: Table 1 It can be seen from the above examples and comparative examples that by adopting the technical solution of the present application, only ferrous sulfate is used, and no additional oxidant is introduced. Through sulfuric acid leaching and pH adjustment, the removal of phosphorus in the phosphorus-containing cobalt intermediate product can be realized, and at the same time, the impurity iron is precipitated; by washing the filter cake with an acid solution, cobalt can be recovered, and the cobalt loss rate is less than 0.1%.

[0043] A method for removing phosphorus from a phosphorus-containing cobalt intermediate product proposed in this application has the following beneficial effects: Utilizing the oxidizing property of Co(OH)3 in the phosphorus-containing cobalt intermediate, no additional oxidant needs to be introduced, reducing the cost of external reagents; realizing the multi-functional utilization of green vitriol, which not only reduces cobalt loss by reducing high-valent cobalt ions as a reducing agent, but also provides a precipitant to remove phosphorus impurities as an iron source; by adjusting the pH, efficient gradient precipitation of phosphorus and iron impurities is achieved.

[0044] The above are only the preferred embodiments of this application, and do not limit the patent scope of this application. Any equivalent structural transformation made using the content of the specification of this application under the inventive concept of this application, or direct / indirect application in other related technical fields, is included in the patent protection scope of this application.

Claims

1. A method for removing phosphorus from a phosphorus-containing cobalt intermediate product, characterized in that, It includes the following steps: S1. Mix ferrous sulfate heptahydrate with a phosphorus-containing cobalt intermediate product and adjust the pulp to form a first pulp after reaction; the phosphorus-containing cobalt intermediate product includes Co(OH)3 and phosphate, and the first pulp includes Fe 3+ ; S2. Add excessive sulfuric acid to the first slurry to form a second slurry; S3. Adjust the pH of the second slurry to generate a precipitate. The precipitate includes FePO4, and filter to obtain a filter cake and a cobalt-containing solution.

2. The method for removing phosphorus from a phosphorus-containing cobalt intermediate product according to claim 1, characterized in that, In step S3, adjust the pH of the second slurry to 2.5 - 4.5 to generate a first precipitate, and further adjust the pH of the second slurry to 4.5 - 5.5 to generate a second precipitate. Filter to obtain a filter cake and a cobalt-containing solution. The first precipitate includes FePO4, and the second precipitate includes Fe(OH)3.

3. A method for removing phosphorus from a phosphorus-containing cobalt intermediate product according to claim 1, characterized in that, After step S3, it further includes: Wash the filter cake with an acid solution to obtain a filtrate and a washed filter cake, and return the filtrate to step S1 for slurry adjustment.

4. A method for removing phosphorus from a phosphorus-containing cobalt intermediate product according to claim 1, characterized in that, 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 is 0.1wt% - 5.0wt% calculated based on phosphorus element.

5. A method for removing phosphorus from a phosphorus-containing cobalt intermediate product according to claim 4, characterized in that, The mass ratio of ferrous sulfate heptahydrate to the phosphorus-containing cobalt intermediate product is 1:20 - 1:

5.

6. A method for removing phosphorus from a phosphorus-containing cobalt intermediate product 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.

7. A method for removing phosphorus from a phosphorus-containing cobalt intermediate product according to claim 1, characterized in that, In step S2, the reaction temperature is 60 - 80°C, and the reaction time is 1 - 3 h; the concentration of the sulfuric acid is 10wt% - 98wt%, and the pH of the second slurry is 1 - 1.

5.

8. A method for removing phosphorus from a phosphorus-containing cobalt intermediate product according to claim 1, characterized in that, In step S3, use an alkaline reagent to adjust the pH, and the reaction temperature is 40 - 60°C; the alkaline reagent includes at least one of a CaCO3 slurry or a Na2CO3 solution; the concentration of the CaCO3 slurry or the Na2CO3 solution is 5wt% - 20wt%.

9. A method for removing phosphorus from a phosphorus-containing cobalt intermediate product according to claim 3, 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.

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

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