Preparation and use method of composite neutralization impurity removal agent in ferrous sulfate solution

Abstract

The invention provides a preparation method and a use method of a composite neutralization impurity removal agent in a ferrous sulfate solution. The method comprises the following steps: taking calcium oxide or calcium hydroxide and hydrogen sulfide gas as raw materials, successfully preparing composite neutralization impurity removal agent slurry through preparation steps of slurrying and vulcanizing, and dropwise adding the composite neutralization impurity removal agent into a ferrous sulfate solution to remove impurities. The impurity removal agent has remarkable neutralization and sulfuration impurity removal effects, the pH value of a ferrous sulfate solution can be adjusted to 5.5, it is ensured that Fe < 3 + > and Al < 3 + > ions in the solution are fully hydrolyzed, and other impurity element ions are effectively removed. Compared with a traditional vulcanization impurity removal agent, the raw materials needed by the method are small in dosage, low in purity requirement, low in price and easy to obtain, and the production cost and the purification cost are greatly reduced. In addition, the H2S gas raw material source is wide, the production cost can be further reduced, and the economic benefit is improved.

Description

Technical Field

[0001] The invention belongs to the field of hydrometallurgy, and particularly relates to a preparation and use method of a composite neutralizing and impurity-removing agent in a ferrous sulfate solution. Background Art

[0002] Battery grade ferrous sulfate refers to ferrous sulfate heptahydrate that has been strictly controlled and contains extremely low levels of impurities such as potassium, sodium, calcium, magnesium, aluminum, copper, zinc, and lead. It is mainly used to manufacture positive electrode materials for lithium iron phosphate (manganese) batteries and sodium ion batteries. However, the ferrous sulfate acid leaching solution often contains a certain amount of residual sulfuric acid (H2SO4) and a large amount of Fe 3+ , AL 3+ ions, and other impurity element ions such as Ni, Co, Cu, Zn, Cr, Cd, As, etc. also have high contents.

[0003] In the traditional process, metal iron powder is usually used to neutralize the residual sulfuric acid and adjust the pH value of the solution to the range of 3.5 to 4.0. Subsequently, the Fe in the solution is removed by hydrolysis. 3+ , AL 3+ ions. Then, sodium sulfide (Na2S), ammonium sulfide ((NH4)2S), barium sulfide (BaS) or other organic sulfide impurity removers are added to further remove other impurity element ions.

[0004] However, this method has several significant problems. First, when using metallic iron powder to adjust the pH value of ferrous sulfate solution, its adjustment ability is limited and can only adjust the pH value of the solution to about 4.0, resulting in the Fe 3+ , AL 3+ The ions are difficult to completely hydrolyze, and the consumption of iron powder is large, and the impurity content of the iron powder is also required to be high, which makes the purification cost of ferrous sulfate solution relatively high. Secondly, when sulfide impurity removers such as sodium sulfide (Na2S) and ammonium sulfide ((NH4)2S) are added, these compounds will inevitably introduce alkaline cations, thereby bringing new impurities, which may have an adverse effect on the quality of the product. The use of barium sulfide (BaS) or other organic sulfide impurity removers is costly and not feasible for actual production applications. Therefore, how to effectively remove impurities in ferrous sulfate solution has always been a major problem that the industry needs to solve urgently. Summary of the invention

[0005] The invention aims to provide a preparation and use method of a composite neutralizing and impurity-removing agent in a ferrous sulfate solution in view of the drawbacks of a traditional process for neutralizing and purifying impurity ions in a ferrous sulfate solution.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A method for preparing and using a composite neutralizing impurity remover in a ferrous sulfate solution comprises the following steps:

[0008] S1: Take calcium oxide (CaO) or calcium hydroxide (Ca(OH)2), the amount of calcium oxide (CaO) or calcium hydroxide (Ca(OH)2) is the amount of the residual acid, Fe 3+ , AL 3+ 1.0 to 1.5 times the theoretical amount of substance required for neutralization and impurity removal with other impurity element ions (calculated as calcium ions);

[0009] S2: Calcium oxide (CaO) or calcium hydroxide (Ca(OH)2) and water are mixed in a weight ratio of 1:4 to 1:3 to obtain a slurry;

[0010] S3: introducing hydrogen sulfide (H2S) gas into the slurry to obtain a composite neutralizing impurity remover; wherein the amount of hydrogen sulfide gas introduced is 0.8 to 1.2 times the amount of calcium oxide (CaO) or calcium hydroxide (Ca(OH)2);

[0011] S4: Add the composite neutralizing and impurity-removing agent dropwise to the ferrous sulfate solution to be purified for reaction. The reaction temperature is 55-65°C, the addition time is 1.5-2.5h, and the pH value of the solution end point is 4.0-5.5. After the addition is completed, continue to react for 10-20min and then filter to hydrolyze and precipitate to remove Fe in the solution. 3+ , AL 3+ ions, and then sulfidation precipitation to remove heavy metal ions and other impurity element ions in the solution to obtain a purified ferrous sulfate solution.

[0012] Preferably, in step S1, the amount of calcium oxide (CaO) or calcium hydroxide (Ca(OH)2) is the amount of the residual acid, Fe 3+ , AL 3+ 1.1 times the theoretical amount of substance required for neutralization and removal of other impurity element ions (calculated as calcium ions).

[0013] Preferably, in step S2, calcium oxide (CaO) or calcium hydroxide (Ca(OH)2) and water are slurried in a weight ratio of 1:4.

[0014] Preferably, in step S3, the amount of hydrogen sulfide (H2S) gas introduced is 1.0 times the amount of calcium oxide (CaO) or calcium hydroxide (Ca(OH)2) substance.

[0015] Preferably, in step S4, the reaction temperature is 60°C, the dropping time is 2.0 hours, the end point pH value of the solution is 5.0, and after the dropping is completed, the reaction is continued for 15 minutes before filtering.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention provides a method for preparing and using a composite neutralizing and impurity-removing agent in a ferrous sulfate solution. Calcium oxide (CaO), calcium hydroxide (Ca(OH)2) and H2S gas are used as raw materials. First, a Ca(OH)2 slurry is prepared according to the reaction equation CaO+H2O=Ca(OH)2, and then H2S gas is introduced. The composite neutralizing and impurity-removing agent Ca(HS)(OH) slurry is successfully prepared through the reaction equations Ca(OH)2+H2S=CaS+H2O and CaS+H2O=Ca(HS)(OH). Since its molecular structure contains OH- and HS- ions, it has significant neutralization and sulfidation impurity-removing effects. The impurity-removing agent can adjust the pH value of the ferrous sulfate solution to 5.5, showing excellent neutralization efficiency, ensuring that the Fe in the ferrous sulfate solution 3+ 、Al 3+ The ions are fully hydrolyzed. As the pH value of the solution increases, the sulfide removal effect of other impurity element ions is also significantly enhanced.

[0018] In addition, the raw materials required for preparing this composite neutralizing and impurity-removing agent - calcium oxide (CaO), calcium hydroxide (Ca(OH)2) and H2S gas, not only have a small amount of use, but also have relatively low purity requirements. In contrast, the addition amount of traditional sulfiding impurity-removing agents such as sodium sulfide (Na2S), ammonium sulfide ((NH4)2S), barium sulfide (BaS) or other organic sulfides is usually 4 to 5 times the theoretical amount of impurity element ions required to be removed, while the composite neutralizing and impurity-removing agent Ca(HS)(OH) of the present invention only needs to neutralize and remove 1.0 to 1.5 times the theoretical amount of impurity element ions. At the same time, calcium oxide (CaO) and calcium hydroxide (Ca(OH)2) are solid raw materials, which are inexpensive and easy to obtain. The H2S gas raw material can be derived from smelting treatment tail gas or high-concentration H2S gas, which has a wide source and greatly reduces the production cost and purification cost.

[0019] Instruction Manual

[0020] Figure 1 The present invention is a process flow chart for the preparation and use of a composite neutralizing and impurity-removing agent in ferrous sulfate solution. DETAILED DESCRIPTION

[0021] The following is a detailed description in conjunction with specific embodiments, but it should be understood that the scope of protection of the present invention is not limited by the specific embodiments. The raw materials used in the examples are all commercially available unless otherwise specified.

[0022] Example 1

[0023] See attached Figure 1, a method for preparing and using a composite neutralizing impurity remover in a ferrous sulfate solution, comprising the following steps:

[0024] (1) Take 1L of ferrous sulfate solution to be purified, weigh calcium oxide (CaO), and weigh the residual acid, Fe 3+ , AL 3+ 1.1 times the theoretical amount of substance required for neutralization and impurity removal with other impurity element ions (calculated as calcium ion);

[0025] (2) slurrying calcium oxide (CaO) and water in a weight ratio of 1:4 to obtain a slurry;

[0026] (3) introducing hydrogen sulfide (H2S) gas into the slurry in an amount of 1.0 times the amount of calcium oxide (CaO) to obtain a composite neutralizing and impurity-removing agent;

[0027] (4) The composite neutralizing and impurity removing agent is added dropwise to the ferrous sulfate solution to be purified for reaction. The reaction temperature is 60°C, the addition time is 2 hours, and the end point pH value of the solution is 5.0. After the addition is completed, the reaction is continued for 15 minutes and then filtered to hydrolyze and precipitate to remove Fe in the solution. 3+ , AL 3+ ions, and then sulfidation precipitation to remove heavy metal ions and other impurity element ions in the solution to obtain a purified ferrous sulfate solution.

[0028] The purified ferrous sulfate solution and product crystallization indexes were tested, and the results are shown in Table 1:

[0029] Table 1 Example 1 Purified ferrous sulfate solution and product crystallization index

[0030]

[0031] Example 2

[0032] See attached Figure 1 , a method for preparing and using a composite neutralizing impurity remover in a ferrous sulfate solution, comprising the following steps:

[0033] (1) Take 1L of ferrous sulfate solution to be purified, weigh calcium hydroxide (Ca(OH)2), weigh the residual acid, Fe 3+ , AL 3+ 1.1 times the theoretical amount of substance required for neutralization and impurity removal with other impurity element ions (calculated as calcium ion);

[0034] (2) slurrying calcium hydroxide (Ca(OH)2) and water in a weight ratio of 1:4 to obtain a slurry;

[0035] (3) introducing hydrogen sulfide (H2S) gas into the slurry in an amount of 1.0 times the amount of calcium hydroxide (Ca(OH)2) to obtain a composite neutralizing and impurity-removing agent;

[0036] (4) The composite neutralizing and impurity removing agent is added dropwise to the ferrous sulfate solution to be purified for reaction. The reaction temperature is 60°C, the addition time is 2 hours, and the end point pH value of the solution is 5.0. After the addition is completed, the reaction is continued for 15 minutes and then filtered to hydrolyze and precipitate to remove Fe in the solution. 3+ , AL 3+ ions, and then sulfidation precipitation to remove heavy metal ions and other impurity element ions in the solution to obtain a purified ferrous sulfate solution.

[0037] The purified ferrous sulfate solution and product crystallization indexes were tested, and the results are shown in Table 2:

[0038] Table 2 Example 2 Purified ferrous sulfate solution and product crystallization index

[0039]

[0040] Example 3

[0041] See attached Figure 1 , a method for preparing and using a composite neutralizing impurity remover in a ferrous sulfate solution, comprising the following steps:

[0042] (1) Take 1L of ferrous sulfate solution to be purified, weigh calcium oxide (CaO), and weigh the residual acid, Fe 3+ , AL 3+ 1.1 times the theoretical amount of substance required for neutralization and impurity removal with other impurity element ions (calculated as calcium ion);

[0043] (2) slurrying calcium oxide (CaO) and water in a weight ratio of 1:4 to obtain a slurry;

[0044] (3) introducing hydrogen sulfide (H2S) gas into the slurry in an amount of 1.0 times the amount of calcium oxide (CaO) to obtain a composite neutralizing and impurity-removing agent;

[0045] (4) The composite neutralizing and impurity removing agent is added dropwise to the ferrous sulfate solution to be purified for reaction. The reaction temperature is 60°C, the addition time is 2 hours, and the pH value of the solution is 4.5. After the addition is completed, the reaction is continued for 15 minutes and then filtered to hydrolyze and precipitate to remove Fe in the solution. 3+ , AL 3+ ions, and then sulfidation precipitation to remove heavy metal ions and other impurity element ions in the solution to obtain a purified ferrous sulfate solution.

[0046] The purified ferrous sulfate solution and product crystallization indexes were tested, and the results are shown in Table 3:

[0047] Table 3 Example 3 Purified ferrous sulfate solution and product crystallization index

[0048]

[0049] It can be clearly seen from Tables 1 to 3 that the method of the present invention is used to purify the ferrous sulfate solution, which can ensure that the Fe 3+ 、Al 3+ The ions are fully hydrolyzed, and at the same time, the sulfide removal effect on other impurity element ions also shows very significant advantages.

[0050] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and illustration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is apparent that many changes and variations are possible in light of the above teachings. The exemplary embodiments are selected and described for the purpose of explaining the specific principles of the present invention and its practical application, thereby enabling those skilled in the art to implement and utilize various exemplary embodiments of the present invention and various selections and variations. The scope of the present invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for preparing and using a composite neutralizing and impurity-removing agent in a ferrous sulfate solution, characterized in that: The following steps are involved: S1: Take calcium oxide or calcium hydroxide, in terms of calcium ions, the amount of calcium oxide or calcium hydroxide is the amount of the residual acid, Fe 3+ , AL 3+ 1.0 to 1.5 times the theoretical amount of substance required for neutralization and impurity removal of other impurity element ions; S2: slurrying calcium oxide or calcium hydroxide with water in a weight ratio of 1:4 to 1:3 to obtain a slurry; S3: introducing hydrogen sulfide gas into the slurry to obtain a composite neutralizing and impurity-removing agent; wherein the amount of hydrogen sulfide gas introduced is 0.8 to 1.2 times the amount of calcium oxide or calcium hydroxide; S4: Add the composite neutralizing and impurity-removing agent dropwise to the ferrous sulfate solution to be purified for reaction. The reaction temperature is 55-65°C, the addition time is 1.5-2.5h, and the pH value of the solution end point is 4.0-5.

5. After the addition is completed, continue to react for 10-20min and then filter to hydrolyze and precipitate to remove Fe in the solution. 3+ , AL 3+ ions, and then sulfidation precipitation to remove heavy metal ions and other impurity element ions in the solution to obtain a purified ferrous sulfate solution.

2. The method for preparation and use according to claim 1, characterized in that: In step S1, the amount of calcium oxide or calcium hydroxide used is the amount of the residual acid, Fe 3+ , AL 3+ 1.1 times the theoretical amount of substance required for neutralization and removal of other impurity element ions.

3. The preparation and use method according to claim 1, characterized in that: In step S2, calcium oxide or calcium hydroxide is slurried with water in a weight ratio of 1:

4.

4. The method for preparation and use according to claim 1, characterized in that: In step S3, the amount of hydrogen sulfide gas introduced is 1.0 times the amount of calcium oxide or calcium hydroxide.

5. The method for preparation and use according to claim 1, characterized in that: In step S4, the reaction temperature is 60°C, the dropping time is 2.0 hours, the end point pH value of the solution is 5.0, and after the dropping is completed, the reaction is continued for 15 minutes before filtering.

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