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CN-121974367-A - Method for realizing high-value recycling of secondary aluminum ash and synchronous deep defluorination and dechlorination by utilizing hydrothermal synthesis

CN121974367ACN 121974367 ACN121974367 ACN 121974367ACN-121974367-A

Abstract

The invention belongs to the technical field of solid waste recycling. The invention discloses a method for realizing high-value recycling of secondary aluminum ash and synchronous deep defluorination and dechlorination by utilizing hydrothermal synthesis. The method comprises the steps of firstly pretreating secondary aluminum ash, preparing slurry with water, and adding a specific defluorinating agent and a specific dechlorinating agent into the slurry to construct a synchronous reaction system. The system carries out hydrothermal reaction under the conditions of high temperature and high pressure, so that fluorine and chlorine elements are respectively fixed and converted into stable compounds. After the reaction is completed, solid-liquid separation is carried out, the obtained solid product can be used as a raw material for preparing zeolite molecular sieves or aluminum-based materials, and the liquid part is subjected to evaporation crystallization to recover salt. The method couples the deep removal of harmful elements and the high-value recycling process of beneficial components to a single hydrothermal system, and realizes the efficient harmless and high-value recycling of the secondary aluminum ash.

Inventors

  • Peng Fengcheng
  • ZHANG FENGLEI
  • ZHOU ZHILIANG
  • ZHENG WEIHONG
  • ZHOU JIAO
  • JIANG SHUHUA
  • DENG HAI
  • WANG RUI

Assignees

  • 重庆市地质矿产勘查开发局川东南地质大队

Dates

Publication Date
20260505
Application Date
20260209

Claims (9)

  1. 1. A method for realizing high-value recycling of secondary aluminum ash and synchronous deep defluorination and dechlorination by utilizing hydrothermal synthesis is characterized by comprising the following steps: s1, grinding and magnetically separating secondary aluminum ash to obtain pretreated aluminum ash; s2, mixing the pretreated aluminum ash and water to obtain slurry; s3, mixing the slurry, the defluorinating agent and the dechlorinating agent, and sequentially carrying out hydrothermal reaction and curing treatment to obtain a reaction product; S4, carrying out solid-liquid separation on the reaction product to obtain filter residues and filtrate, wherein the filter residues are used as raw materials for preparing zeolite molecular sieves or aluminum-based inorganic materials, and the filtrate is subjected to evaporation crystallization to recover soluble salts.
  2. 2. The method for realizing high-value recycling and synchronous deep defluorination and dechlorination of the secondary aluminum ash by utilizing the hydrothermal synthesis according to claim 1, wherein in the step S1, the average grain diameter D 50 of the ground aluminum ash is less than or equal to 45 μm.
  3. 3. The method for realizing high-value recycling and synchronous deep defluorination and dechlorination of the secondary aluminum ash by utilizing the hydrothermal synthesis according to claim 2, wherein in the step S2, the mass ratio of the pretreated aluminum ash to water is 1 g:3-10 mL.
  4. 4. The method for realizing high-value recycling and synchronous deep defluorination and dechlorination of secondary aluminum ash by utilizing hydrothermal synthesis according to any one of claims 1-3, wherein in the step S2, a silicon source regulator is further added in the preparation process of slurry, the dosage of the silicon source regulator is 2-30% of the mass of the pretreated aluminum ash, and the silicon source regulator is sodium silicate, white carbon black or fly ash.
  5. 5. The method for realizing high-value recycling and synchronous deep defluorination and dechlorination of the secondary aluminum ash by utilizing hydrothermal synthesis according to claim 4, wherein in the step S3, the defluorination agent is a lanthanum or cerium-containing compound, and the dechlorination agent is silver nitrate or silver sulfate.
  6. 6. The method for realizing high-value recycling and synchronous deep defluorination and dechlorination of secondary aluminum ash by utilizing hydrothermal synthesis according to claim 1, wherein the mass ratio of the pretreatment aluminum ash to the defluorination agent to the dechlorination agent is 100:5-20:3-15.
  7. 7. The method for realizing high-value recycling and synchronous deep defluorination of the secondary aluminum ash by utilizing the hydrothermal synthesis according to claim 5 is characterized in that in the step S3, the hydrothermal reaction is divided into three stages, wherein the temperature of the first stage is 120-150 ℃, the time is 0.5-1 h, the temperature of the second stage is 180-220 ℃, the time is 1-4 h, the temperature of the third stage is 240-260 ℃ and the time is 0.5-2 h.
  8. 8. The method for realizing recycling and synchronous deep defluorination and dechlorination of secondary aluminum high-value ash by utilizing hydrothermal synthesis according to claim 7, wherein in the step S3, the curing treatment temperature is 80-100 ℃ and the time is 2-12 h.
  9. 9. The method for realizing recycling and synchronous deep defluorination and dechlorination of secondary aluminum high-value ash by utilizing hydrothermal synthesis according to claim 5, wherein in the step S4, a multistage countercurrent evaporation crystallization process is adopted for the filtrate, wherein the primary evaporation crystallization temperature is 80-95 ℃, mixed salt of sodium chloride and potassium chloride is separated out, the secondary evaporation crystallization temperature is 60-75 ℃, and double salt precipitation corresponding to rare earth elements in fluorine-containing defluorinating agent is separated out.

Description

Method for realizing high-value recycling of secondary aluminum ash and synchronous deep defluorination and dechlorination by utilizing hydrothermal synthesis Technical Field The invention relates to the technical field of solid waste recycling, in particular to a method for realizing high-value recycling of secondary aluminum ash and synchronous deep defluorination and dechlorination by utilizing hydrothermal synthesis. Background The secondary aluminum ash is a dangerous solid waste generated in the aluminum industrial production process, has large production amount, complex components, difficult treatment and recycling, contains a large amount of harmful substances such as fluoride, chloride, aluminum nitride, heavy metal and the like, and is extremely easy to cause serious harm to the environment and the health of people if improperly treated. At present, the treatment of the secondary aluminum ash remains in a harmless stage for removing harmful substances therein, and technical routes such as water washing, roasting and the like are generally explored in the industry. Although part of soluble salts can be dissolved out by the water washing method, the removal efficiency of fluorine and chlorine is limited, fluorine elements are difficult to fix effectively, and aluminum nitride is easy to hydrolyze and release ammonia gas in the treatment process, so that secondary pollution, potential safety and environmental risk are caused. Although the roasting method can treat aluminum nitride, the energy consumption is high, fluoride can volatilize and escape at high temperature, thorough solidification is difficult to realize, and meanwhile, chlorine is not completely removed. Therefore, most of the existing processes only focus on harmless treatment of the secondary aluminum ash, or only realize low-level recycling, cannot cooperatively finish removing harmful elements and constructing high-value products in the same system, have the inherent defects of long process flow, low resource utilization rate, low added value of terminal products and the like, lack a recycling method capable of synchronously realizing deep defluorination and dechlorination of the secondary aluminum ash and converting valuable components in the aluminum ash into high-added-value products, and do not meet the development trend of solid waste treatment and recycling technology and the national circular economy development requirements. Therefore, the development of a novel method which is efficient and thorough and can realize comprehensive recycling of the secondary aluminum ash is oriented to safe high-value utilization, and the method becomes a key technical problem to be solved in the field. Disclosure of Invention The invention aims to provide a method for realizing recycling of secondary aluminum ash and synchronous defluorination and dechlorination by utilizing hydrothermal synthesis, which is used for solving the technical problem that the existing secondary aluminum ash treatment technology cannot synchronously realize deep defluorination and dechlorination and high added value recycling in the same system. In order to achieve the above object, the present invention provides the following technical solutions: The invention discloses a method for realizing high-value recycling and synchronous deep defluorination and dechlorination of secondary aluminum ash by utilizing hydrothermal synthesis, which comprises the following steps: s1, grinding and magnetically separating secondary aluminum ash to obtain pretreated aluminum ash; s2, mixing the pretreated aluminum ash and water to obtain slurry; s3, mixing the slurry, the defluorinating agent and the dechlorinating agent, and sequentially carrying out hydrothermal reaction and curing treatment to obtain a reaction product; S4, carrying out solid-liquid separation on the reaction product to obtain filter residues and filtrate, wherein the filter residues are used as raw materials for preparing zeolite molecular sieves or aluminum-based inorganic materials, and the filtrate is subjected to evaporation crystallization to recover soluble salts. Further, in the step S1, the average particle diameter D 50 of the aluminum ash after grinding is less than or equal to 45 μm. Further, in the step S2, the mass ratio of the pretreated aluminum ash to the water is 1 g:3-10 mL. Further, in the step S2, a silicon source regulator is also added in the preparation process of the slurry, the dosage of the silicon source regulator is 2-30% of the mass of the pretreated aluminum ash, and the silicon source regulator is sodium silicate, white carbon black or fly ash. In the step S3, the defluorinating agent is a compound containing lanthanum or cerium, and the dechlorinating agent is silver nitrate or silver sulfate. Further, the mass ratio of the pretreatment aluminum ash to the defluorinating agent to the dechlorinating agent is 100:5-20:3-15. Further, in the step S3, the hydrothermal reaction is divide