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CN-122010070-A - Method for continuously preparing battery-grade ferric phosphate by taking raffinate acid as raw material

CN122010070ACN 122010070 ACN122010070 ACN 122010070ACN-122010070-A

Abstract

The invention relates to the technical field of ferric phosphate production, and discloses a method for continuously preparing battery grade ferric phosphate by taking raffinate acid as a raw material, which comprises the following steps of 1) dissolving ferrous sulfate heptahydrate, adding ammonia water, and removing impurities to obtain ferrous sulfate solution A; 2) diluting raffinate acid, adding ammonia water and a fluorination auxiliary agent to remove impurities to obtain a mixed solution B, 3) adding an oxidant and a pH regulator to the mixed solution B to obtain a mixed solution C, 4) adding the ferrous sulfate solution A into a first-stage reaction kettle at a constant speed, continuously adding the solution C into a first-stage reaction kettle, a second-stage reaction kettle and a third-stage reaction kettle which are connected in series in a split manner to synthesize the solution C, filtering and washing the obtained slurry to obtain a filter cake, 5) mixing the filter cake with phosphoric acid, heating to convert crystals, changing colors to obtain aged slurry, and filtering, washing, drying, calcining and crushing to obtain the battery-grade ferric phosphate. The invention uses low-cost raffinate acid to replace high-cost monoammonium phosphate or phosphoric acid and other raw materials, combines a continuous process, obviously reduces the cost and improves the stability and quality of product batches.

Inventors

  • ZHA ZUOTONG
  • WANG JUNTING
  • MA HANG
  • WAN BANGLONG
  • WEI XING
  • ZHANG ZHENHUAN
  • CHEN ZHANGHONG

Assignees

  • 云南云天化股份有限公司

Dates

Publication Date
20260512
Application Date
20260113

Claims (9)

  1. 1. The method for continuously preparing the battery-grade ferric phosphate by taking the raffinate acid as the raw material is characterized by comprising the following steps of: 1) Continuously introducing ferrous sulfate heptahydrate, ammonia water and pure water into a multistage serial ferrous reaction tank for impurity removal reaction, and filtering the reaction slurry to obtain ferrous sulfate solution A; 2) Continuously introducing raffinate acid, ammonia water, a fluorination auxiliary agent and pure water into a phosphorus salt reaction tank for impurity removal reaction, filtering reaction slurry to obtain phosphorus salt solution B, and mixing the phosphorus salt solution B with an oxidant and ammonia water to obtain mixed solution C; 3) Continuously adding ferrous sulfate solution A into a first-stage reaction kettle at a constant flow rate, continuously and simultaneously adding a mixed solution C into the first-stage reaction kettle, a second-stage reaction kettle and a third-stage reaction kettle after the mixed solution C is split, and carrying out synthetic reaction to obtain synthetic slurry, and filtering and washing the synthetic slurry to obtain a synthetic filter cake, wherein the first-stage reaction kettle, the second-stage reaction kettle and the third-stage reaction kettle are arranged in series; 4) And continuously conveying the synthesized filter cake to a slurry mixing kettle, adding pure water and phosphoric acid to complete dispersion, continuously and sequentially pumping the obtained slurry into a primary aging kettle and a secondary aging kettle which are connected in series to perform crystal transformation aging, and filtering, washing, drying, calcining and crushing the aged slurry to obtain the battery-grade ferric phosphate.
  2. 2. The method for continuously preparing battery-grade ferric phosphate by using raffinate acid as a raw material according to claim 1, wherein the impurity removal reaction temperature in the step 1) and the step 2) is 55-65 ℃, and the impurity removal reaction pH value in the step 2) is 3-7.
  3. 3. The method for continuously preparing battery-grade ferric phosphate by using raffinate acid as a raw material according to claim 1, wherein the multistage series ferrous reaction tanks are a ferrous reaction tank 1, a ferrous reaction tank 2 and a ferrous reaction tank 3 which are sequentially connected, and the retention time of materials in each stage of ferrous reaction tank is 20-30 min respectively.
  4. 4. The method for continuously preparing battery-grade ferric phosphate by using raffinate acid as a raw material, which is characterized in that the residence time of materials in a primary reaction kettle, a secondary reaction kettle and a tertiary reaction kettle is respectively 10-20 min, and the residence time of materials in a primary aging kettle and a secondary aging kettle is respectively 40-60 min.
  5. 5. The method for continuously preparing battery-grade ferric phosphate by using raffinate acid as raw material according to claim 1, wherein the concentration of P 2 O 5 of the raffinate acid is 20% -50%.
  6. 6. The method for continuously preparing battery-grade ferric phosphate by using raffinate acid as a raw material according to claim 1, wherein the fluorination aid is ammonium fluoride or sodium fluosilicate, and the addition mass of the fluorination aid is 0.5% -3% of the mass of the raffinate acid.
  7. 7. The method for continuously preparing battery-grade ferric phosphate by using raffinate acid as a raw material according to claim 1, wherein the oxidant is hydrogen peroxide, and the molar ratio of the oxidant to Fe 2+ in the ferrous sulfate solution A is 1.1-1.4:1.
  8. 8. The method for continuously preparing battery-grade ferric phosphate by using raffinate acid as a raw material, which is characterized in that the pH value of a mixed solution C is 6.5-7.5, the ratio of the adding flow rate of a ferrous sulfate solution A to the adding flow rate of the mixed solution C is 1.5-3:1, the adding flow rate of the mixed solution C in a first-stage reaction kettle, a second-stage reaction kettle and a third-stage reaction kettle is 4-6:3-2:3-2, the constant temperature of the first-stage reaction kettle, the second-stage reaction kettle and the third-stage reaction kettle is 50-60 ℃, and the pH value of a reaction system is 1.5-2.5.
  9. 9. The method for continuously preparing battery-grade ferric phosphate by using raffinate acid as a raw material, which is characterized in that the constant temperature of the size mixing kettle is 40-60 ℃, the pH value of the obtained size mixing slurry is controlled to be 1.0-2.5 by adding phosphoric acid, and the constant temperature of the primary aging kettle and the secondary aging kettle is 85-95 ℃.

Description

Method for continuously preparing battery-grade ferric phosphate by taking raffinate acid as raw material Technical Field The invention relates to the technical field of iron phosphate production, in particular to a method for continuously preparing battery-grade iron phosphate by taking raffinate acid as a raw material. Background In recent years, new energy industry is exploded, so that the industrial productivity is excessive, iron phosphate production enterprises face multiple challenges, and the overall situation is relatively tense. Wherein, due to rising raw material price, rising energy cost and improving environmental protection requirement, the market competition is intense, so that the selling price of the product is continuously low, the profit margin is severely extruded, the industry is urgently required to reduce the cost through technical innovation and process optimization, and the market competitiveness is improved. At present, the main flow process for producing ferric phosphate is an ammonium method process, and the adopted phosphorus source is usually battery grade or high-quality monoammonium phosphate, and the phosphorus source accounts for more than 30% in the composition of the production cost, so that the production cost is high under the conditions of surplus productivity and continuous low selling price of products. The raffinate acid is a byproduct in the process of producing the refined phosphoric acid, and is mainly derived from residual liquid of wet-process phosphoric acid purified by a solvent extraction method, and 1 ton of raffinate acid can be produced when 1 ton of refined phosphoric acid with the mass fraction of P 2O5 being 46% -54% is produced. Since impurities (such as metal ions of iron, aluminum, magnesium and the like) of the crude phosphoric acid are enriched into the raffinate acid in the extraction process, the content of metal impurities in the raffinate acid is high. In the process of synthesizing ferric phosphate by a liquid phase precipitation method, the accurate regulation and control of the pH value of a reaction system has important influence on the formation of ferric phosphate crystals and the quality of products. On one hand, the pH value of the reaction system is ensured to be in an optimal precipitation interval of ferric phosphate so as to ensure the efficient precipitation of target products, and on the other hand, the problem that the purity of the product is adversely affected due to synchronous precipitation of most impurity ions caused by improper control of the pH value is avoided, so that the quality of the battery-grade ferric phosphate product is difficult to meet the demands of downstream customers. In order to further improve the product quality and the production efficiency, the continuous production process of the ferric phosphate is actively researched and developed. The continuous production process can avoid frequent start-stop operation of traditional intermittent production, reduce energy consumption and time loss, greatly improve production efficiency, reduce labor cost, easily realize strict control on reaction conditions such as temperature, time and flow, ensure that the production process is more stable, and are favorable for improving the quality consistency of ferric phosphate products. The prior preparation method for reducing the production cost of the ferric phosphate adopts a means of replacing raw materials in order to reduce the raw material cost, for example, the method disclosed in CN117585653A adopts phosphorite, pyrite, phosphated slag, low-quality acid, agricultural monoammonium and other acid-dissolved leaching solutions with phosphorus grade lower than 20 percent as a phosphorus source, and adopts the acid-dissolved leaching solutions such as pyrite, pyrite cinder, waste iron blocks and the like as an iron source to prepare crude ferric phosphate through mixing, oxidizing and precipitating steps. In another method disclosed in CN118405676A, after three-stage countercurrent extraction is performed on the raffinate, back extraction, concentration defluorination, chemical defluorination, re-extraction and re-back extraction are performed to obtain NH4H2PO4 solution, and the obtained raw material reacts with ferrous sulfate to obtain ferric phosphate. However, the method requires repeated extraction of the raffinate acid for many times, the raffinate acid cannot be directly used, the requirement of the iron phosphate synthetic raw material can be met only by extraction and purification treatment in advance, the production cost is increased due to complicated processes of expensive extractant, multiple extractions and back extraction, and the method is not suitable for industrialized mass production. The existing method for continuously preparing ferric phosphate has the following problems that in the method disclosed in CN118619227A, ferric salt and phosphonium salt are mixed in a reaction kettle in a ratio of 1: