CN-119079955-B - Method for recycling battery-grade ferric phosphate from sludge

Abstract

The invention relates to the technical field of sludge recycling, in particular to a method for recycling battery-grade ferric phosphate from sludge. The method comprises the steps of incinerating dried sludge to obtain sludge incineration ash, leaching the sludge incineration ash by utilizing target acid liquor with a first preset concentration, obtaining phosphorus-containing leaching liquid after solid-liquid separation, adding an Fe source into the phosphorus-containing leaching liquid to obtain a mixed solution, and carrying out hydrothermal synthesis on the mixed solution to obtain the battery-grade ferric phosphate. Therefore, the technical scheme is that the hydrothermal synthesis treatment is directly carried out on the phosphorus-containing leaching solution added with the Fe source, so that the process flow for preparing the battery-grade ferric phosphate can be shortened.

Inventors

• LIU HUAN
• JIN MINGHAO
• Ma chuangye
• YAO HONG

Assignees

• 华中科技大学

Dates

Publication Date

20260505

Application Date

20240830

Claims (6)

1. 1. A method of recovering battery grade ferric phosphate from sludge, comprising: incinerating the dried sludge to obtain sludge incineration ash; Leaching the sludge incineration ash by utilizing target acid liquor with a first preset concentration, and carrying out solid-liquid separation to obtain phosphorus-containing leaching liquor; adding an Fe source into the phosphorus-containing leaching solution to obtain a mixed solution; carrying out hydrothermal synthesis on the mixed solution to obtain battery-grade ferric phosphate; The target acid liquid comprises at least one of sulfuric acid and nitric acid, and the first preset concentration is 0.02-0.15 mol/L so as to ensure that the pH value of the phosphorus-containing leaching solution is 0.4-2.1; the reaction temperature of the hydrothermal synthesis is 150-210 ℃ and the reaction time is 1-24 h; the hydrothermal synthesis of the mixed solution to obtain battery grade ferric phosphate comprises the following steps: carrying out hydrothermal synthesis on the mixed solution to obtain a hydrothermal synthesis product; carrying out solid-liquid separation on the hydrothermal synthesis product to obtain a solid product; washing the solid product by using a washing liquid, and freeze-drying the washed solid product; firing the solid product after freeze drying in air atmosphere to obtain battery grade ferric phosphate; The washing liquid comprises a first washing liquid and a second washing liquid, the first washing liquid is dilute nitric acid or dilute sulfuric acid with a second preset concentration, and the second washing liquid is deionized water; The washing of the solid product with a washing liquid comprises: and washing the solid product sequentially by using the first washing liquid and the second washing liquid.
2. 2. The method of claim 1, wherein the phosphorus-containing leachate is used for recycle leaching of new sludge incineration ash.
3. 3. The method of claim 1, wherein the Fe source comprises at least one of FeCl 3 、Fe(NO 3 ) 3 and Fe 2 (SO 4 ) 3 , and the molar ratio of the Fe source to phosphorus element in the phosphorus-containing leachate is 1-1.05:1.
4. 4. The method of claim 1, further comprising, after said freeze-drying the washed solid product: adding a reducing agent and a Li source into the solid product after freeze drying; And heating the solid product added with the reducing agent and the Li source in an inert atmosphere to obtain the battery-grade lithium iron phosphate.
5. 5. The method of claim 4, wherein the reducing agent comprises at least one of H 2 and a carbon source comprising at least one of glucose, sucrose, starch, and the Li source comprises at least one of LiOH and Li 2 CO 3 .
6. 6. The method according to claim 5, wherein when the reducing agent is H 2 , the gas volume ratio of the reducing agent to the inert gas in the solid product is 5 to 95%, and/or, When the reducing agent is a carbon source, the adding amount of the reducing agent is 0.5-10% of the total mass of the freeze-dried solid product, and/or, The molar ratio of Fe source to Li source in the solid product is 1:1.05.

Description

Method for recycling battery-grade ferric phosphate from sludge Technical Field The invention relates to the technical field of sludge recycling, in particular to a method for recycling battery-grade ferric phosphate from sludge. Background The pollutants and nutrient components in the sewage are aggregated under the action of a large number of propagated bacteria and under the action of chemical agents, and finally sludge is formed. With the rapid development of industries such as new energy automobiles, energy storage batteries and the like, the yield of battery-grade ferric phosphate is continuously increased, so that the demand of production raw materials (such as phosphorus element) is increased. In the related art, a method for recovering phosphorus from sludge and preparing battery-grade ferric phosphate mainly adopts a wet chemical method, however, the process flow of the method is long. Therefore, there is a need for a method of recovering battery grade ferric phosphate from sludge to solve the technical problem. Disclosure of Invention The invention provides a method for recycling battery-grade ferric phosphate from sludge, which can shorten the process flow for preparing the battery-grade ferric phosphate. The invention provides a method for recovering battery-grade ferric phosphate from sludge, which comprises the following steps: incinerating the dried sludge to obtain sludge incineration ash; Leaching the sludge incineration ash by utilizing target acid liquor with a first preset concentration, and carrying out solid-liquid separation to obtain phosphorus-containing leaching liquor; adding an Fe source into the phosphorus-containing leaching solution to obtain a mixed solution; and carrying out hydrothermal synthesis on the mixed solution to obtain the battery grade ferric phosphate. According to the method for recycling the battery-grade ferric phosphate from the sludge, disclosed by the invention, the dried sludge is incinerated to obtain the sludge incineration ash, the sludge incineration ash is leached by utilizing the target acid liquor with the first preset concentration, the phosphorus-containing leaching solution is obtained after solid-liquid separation, the Fe source is added into the phosphorus-containing leaching solution to obtain the mixed solution, and the mixed solution is subjected to hydrothermal synthesis to obtain the battery-grade ferric phosphate. Therefore, the technical scheme is that the hydrothermal synthesis treatment is directly carried out on the phosphorus-containing leaching solution added with the Fe source, so that the process flow for preparing the battery-grade ferric phosphate can be shortened. Drawings In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are some embodiments of the invention and that other drawings may be obtained based on these drawings without inventive effort for a person skilled in the art. FIG. 1 is a schematic diagram of a method for recovering battery grade ferric phosphate from sludge according to an embodiment of the present invention; FIG. 2 is a graph comparing iron phosphate recovered by the present process with commercial grade iron phosphate provided by an embodiment of the present invention; FIG. 3 is a diagram of a thermodynamic equilibrium calculation system for precipitation reaction of impurity components in a phosphorus-containing leachate and a target phosphorus-containing product provided in an embodiment of the present invention; FIG. 4 is a Gibbs free energy diagram of an iron phosphate precipitation reaction according to an embodiment of the present invention; FIG. 5 is a graph showing the equilibrium constants of the iron phosphate precipitation reaction according to the present invention. Detailed Description For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments, and all other embodiments obtained by persons of ordinary skill in the art without making any inventive effort based on the embodiments of the present invention are within the scope of protection of the present invention. Referring to fig. 1, one embodiment of the present invention provides a method for recovering battery grade ferric phosphate from sludge, the method comprising: step 100, incinerating the dried sludge to obtain sludge incineration ash; Step 102, leaching the sludge incineration ash by utilizing target a