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CN-122010187-A - Method for preparing battery-grade ferrous sulfate from titanium dioxide byproduct ferrous sulfate

CN122010187ACN 122010187 ACN122010187 ACN 122010187ACN-122010187-A

Abstract

The invention discloses a method for preparing battery grade ferrous sulfate from titanium dioxide byproduct ferrous sulfate, which comprises the steps of (1) heating and dissolving titanium dioxide byproduct ferrous sulfate in a solvent to form a ferrous sulfate supersaturated solution, (2) sequentially adding iron powder and sulfuric acid into the ferrous sulfate supersaturated solution to enable the ferrous sulfate supersaturated solution to undergo a reduction reaction, (3) adding a chelating agent into the solution obtained in the step (2), mixing, filtering and cooling, carrying out solid-liquid separation to obtain recrystallized ferrous sulfate crystals and recrystallized saturated mother liquor, and (4) heating and dissolving the recrystallized ferrous sulfate crystals into the supersaturated solution by using the solvent, cooling and crystallizing, and repeating the recrystallization step to obtain the battery grade ferrous sulfate. According to the invention, a chemical chelating method and a recrystallization method are combined, sodium lignin sulfonate is added into mother liquor before the first recrystallization as a chelating agent, so that a stable compound is formed with metal impurity ions, and meanwhile, the enrichment of impurity ions in the circulation process of the mother liquor is avoided, and the purity of ferrous sulfate crystals is improved.

Inventors

  • TANG ZIJUN
  • SHI YINGFEI
  • PAN LONG
  • CHENG FEI
  • CHEN EN
  • WANG KAI
  • ZHAO WEISEN
  • SHI JUNFENG

Assignees

  • 南京锂源纳米科技有限公司
  • 常州锂源新能源科技有限公司
  • 锂源(亚太)新能源科技有限公司

Dates

Publication Date
20260512
Application Date
20260226

Claims (10)

  1. 1. The method for preparing the battery-grade ferrous sulfate from the titanium dioxide byproduct ferrous sulfate is characterized by comprising the following steps of: (1) Heating and dissolving titanium dioxide byproduct ferrous sulfate in a solvent to form a ferrous sulfate supersaturated solution; (2) Iron powder and sulfuric acid are sequentially added into the ferrous sulfate supersaturated solution to enable the ferrous sulfate supersaturated solution to undergo a reduction reaction; (3) Adding a chelating agent into the solution obtained in the step (2), mixing, filtering and cooling, and carrying out solid-liquid separation to obtain recrystallized ferrous sulfate crystals and recrystallized saturated mother liquor; (4) And heating and dissolving the recrystallized ferrous sulfate crystals into supersaturated solution by using a solvent, cooling and crystallizing, and repeating the recrystallization step to obtain the battery-grade ferrous sulfate.
  2. 2. The method for preparing battery grade ferrous sulfate from titanium dioxide byproduct ferrous sulfate according to claim 1, wherein in step (1), the mass ratio of titanium dioxide byproduct ferrous sulfate to solvent is 1-3:1.
  3. 3. The method of claim 1, wherein in step (1), the temperature of the heating dissolution is 50-70 ℃.
  4. 4. The method for preparing battery grade ferrous sulfate from titanium dioxide byproduct ferrous sulfate according to claim 1, wherein in the step (2), the addition amount of the iron powder is 1-2% of the mass of titanium dioxide byproduct ferrous sulfate.
  5. 5. The method of claim 1, wherein in step (2), the sulfuric acid is added in an amount to adjust the pH of the supersaturated solution of ferrous sulfate to 0.5-1.5.
  6. 6. The method for preparing battery grade ferrous sulfate from titanium dioxide byproduct ferrous sulfate of claim 1, wherein in step (2), the time of the reduction reaction is 0.5-1.5h.
  7. 7. The method of claim 1, wherein in step (3), the chelating agent is sodium lignosulfonate.
  8. 8. The method for preparing battery grade ferrous sulfate from titanium dioxide byproduct ferrous sulfate according to claim 1 or 7, wherein in the step (3), the chelating agent is added in an amount of 1-3% of the mass of titanium dioxide byproduct ferrous sulfate.
  9. 9. The method for preparing battery grade ferrous sulfate from titanium dioxide byproduct ferrous sulfate of claim 1, wherein in step (3), the filtering is hot.
  10. 10. The method for preparing battery grade ferrous sulfate from titanium dioxide byproduct ferrous sulfate according to claim 1, wherein in the step (4), the number of repeated recrystallization is more than or equal to 3, and when the total weight is crystallized for the nth time, the (n+1) th time of obtained recrystallized saturated mother liquor is used for dissolving the (N-1) th ferrous sulfate crystal in the next round of preparation of battery grade ferrous sulfate, and wherein the second time of obtained recrystallized saturated mother liquor is used for dissolving the titanium dioxide byproduct ferrous sulfate in the step (1) in the next round of preparation of battery grade ferrous sulfate.

Description

Method for preparing battery-grade ferrous sulfate from titanium dioxide byproduct ferrous sulfate Technical Field The invention belongs to the field of recycling of titanium dioxide byproducts, and particularly relates to a method for preparing battery-grade ferrous sulfate from titanium dioxide byproduct ferrous sulfate. Background Ferrous sulfate heptahydrate is a main byproduct in the production process of titanium dioxide, and is widely applied to industries such as chemical industry, new energy and the like, however, the byproduct contains a large amount of Mn, mg, ti, al, co and other impurity metal elements, cannot be directly applied to the production in the industries such as chemical industry, new energy and the like, and can be used after purification. At present, the purification modes of the titanium dioxide byproduct ferrous sulfate mainly comprise a chemical precipitation method and a recrystallization method. The chemical precipitation method mainly removes impurity ions in a precipitation mode by adding fluoride, sulfide, phosphoric acid or alkali and the like, for example, CN107640790A precipitates the impurity ions by using ammonia water and a flocculating agent to prepare high-purity ferrous sulfate crystals, but the removal effect of the high-purity ferrous sulfate crystals on the impurity ions is limited, the recrystallization method utilizes the solubility difference of ferrous sulfate and other impurity ions, and adopts the modes of heating, dissolving and cooling crystallization to separate out the ferrous sulfate from a solution in a crystal mode, but in order to ensure the separation rate of the ferrous sulfate in the traditional recrystallization mode, the recrystallization operation generally needs to reduce the temperature to about 5 ℃, so that the energy consumption cost is increased, and the impurity ions still contained in the finished ferrous sulfate can not be completely removed by one to two times of recrystallization, so that the requirement of battery-grade ferrous sulfate can not be met. Disclosure of Invention The invention aims to provide a method for preparing battery-grade ferrous sulfate from titanium dioxide byproduct ferrous sulfate. The technical scheme is that the method for preparing battery-grade ferrous sulfate from titanium dioxide byproduct ferrous sulfate comprises the following steps: (1) Heating and dissolving titanium dioxide byproduct ferrous sulfate in a solvent to form a ferrous sulfate supersaturated solution; (2) Iron powder and sulfuric acid are sequentially added into the ferrous sulfate supersaturated solution to enable the ferrous sulfate supersaturated solution to undergo a reduction reaction; (3) Adding a chelating agent into the solution obtained in the step (2), mixing, filtering and cooling, and carrying out solid-liquid separation to obtain recrystallized ferrous sulfate crystals and recrystallized saturated mother liquor; (4) And heating and dissolving the recrystallized ferrous sulfate crystals into supersaturated solution by using a solvent, cooling and crystallizing, and repeating the recrystallization step to obtain the battery-grade ferrous sulfate. In the step (1), the mass ratio of the titanium dioxide byproduct ferrous sulfate to the solvent is 1-3:1, so that a stable ferrous sulfate supersaturated solution can be formed, the ion concentration of impurity ions Al, mn, mg, ti can be controlled to be at a proper level, and the co-precipitation of the impurity ions in the crystallization process can be controlled to be at a lower level, thereby reducing the impurity ion content in the ferrous sulfate. In the step (1), the temperature of heating and dissolving is 50-70 ℃, and in the temperature range, the solubility of ferrous sulfate is effectively improved, so that the precipitation rate of ferrous sulfate in the cooling process is improved, but the overhigh heating temperature can lead ferrous sulfate heptahydrate to lose crystal water and be converted into ferrous sulfate monohydrate, so that the solubility is reduced, and the heating energy consumption is increased. Preferably, in the step (1), the heating and dissolving time is 0.5-1.5h, and the proper stirring time can enable ferrous sulfate to be fully dissolved. In the step (2), the addition amount of the iron powder is 1-2% of the mass of the titanium dioxide byproduct ferrous sulfate, and the iron powder is used for reducing ferric iron in the titanium dioxide byproduct ferrous sulfate, so that the reaction of ferric iron and a chelating agent is avoided, the impurity ion removal rate is reduced, and excessive impurity ions are introduced in the recrystallization process. In the step (2), the addition amount of the sulfuric acid is that the pH value of the supersaturated solution of ferrous sulfate is regulated to 0.5-1.5, the addition of the sulfuric acid can reduce the pH value of the system, the generation of ferric hydroxide is avoided, meanwhile, the oxidation of f