Method for treating fluorine-containing waste electrolyte

A waste electrolyte and content technology, applied in chemical instruments and methods, aluminum fluoride, alkali metal sulfite/sulfite, etc., can solve low raw material utilization rate, unfavorable mass transfer crystallization, and low effective aluminum fluoride content To achieve the effect of improving the purity and fluorine recovery rate, increasing the mass transfer rate, and promoting the reaction

Active Publication Date: 2021-07-23
CENT SOUTH UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

It can be seen that the composition of spent electrolytes is complex, which brings great challenges to the separation and extraction of valuable components.
Chinese patent application specification CN108677020A, CN110668483A, CN111517349A, CN109759423A and CN110194478A etc. provide a series of wet treatment process of waste electrolyte, all adopt acid or (and) aluminum salt to process waste electrolyte, use cryolite, aluminum fluoride or hydroxyl fluoride Recovering aluminum and fluorine elements in the electrolyte in the form of aluminum, etc., the process is long, the recovery rate is low, the acidic leachate has high requirements for equipment, and the further treatment of the wastewater generated in the process is still a problem
Recently, the Chinese patent application specification CN111485252A provides a dry processing process similar to the above-mentioned RU2462418C1 patent. Its hydrate polymer, etc.; in fact, the boiling point of aluminum chloride is 181 ° C, which is not conducive to the r

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  • Method for treating fluorine-containing waste electrolyte
  • Method for treating fluorine-containing waste electrolyte
  • Method for treating fluorine-containing waste electrolyte

Examples

Experimental program
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Effect test

Embodiment 1

[0038] The steps of the method for treating waste electrolytes containing fluorine in this embodiment are as follows:

[0039] (1) Take 50kg of waste electrolyte from an electrolytic aluminum plant (XRF fluorescence analysis: F 49.68wt.%, Na 21.48wt.%, Al14.48%, Ca 5.46, K 5.13wt.%, O 2.59wt.%, Mg 0.57 wt.%, S 0.18wt.%), crushed to less than 2mm, to obtain waste electrolyte powder, and set aside;

[0040] (2) Take 100kg of aluminum sulfate octadecahydrate and heat it up to 300°C at a rate of 10°C / min, keep it warm for 2 hours, then raise the temperature to 400°C, keep it warm for 2 hours, break it down to less than 2mm after cooling, weigh it, and obtain anhydrous aluminum sulfate powder 51.5 kg for use;

[0041] (3) Take 48kg of spent electrolyte powder, 43kg of anhydrous aluminum sulfate powder and 1.5kg of sodium carbonate and mix evenly, then ball mill until passing through a 100-mesh sieve to obtain mixed powder.

[0042] (4) Put the mixed powder obtained in step (3) in...

Embodiment 2

[0047] Get 50kg of the same waste electrolyte as in Example 1, change the temperature in step (4) to 600°C, and keep other conditions constant, repeat the steps (1)-(6) of Example 1, and finally get 38.6kg of aluminum fluoride product, Obtain by-product potassium sulfate 10.8kg, by-product sodium sulfate 40.5kg. The obtained aluminum fluoride was detected, and the results are shown in Table 1.

Embodiment 3

[0049] Repeat Example 1, the only difference is: the temperature in step (4) is controlled to 580 ° C, and the obtained aluminum fluoride product is tested, and the results are shown in Table 1.

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Abstract

The invention discloses a method for efficiently treating fluorine-containing waste electrolyte, which comprises the following steps: adding an additive and a reaction aid into the waste electrolyte, uniformly mixing, grinding to below 0.355 mm, roasting, cooling at a specific rate, crushing and washing to obtain an aluminum fluoride product, and concentrating filtrate to further extract other byproducts. According to the invention, the reaction aid is added to reduce the primary crystal temperature of the system, so that the reaction is carried out in a molten state, the mass transfer efficiency is high, the reaction conversion rate is high, and the content of effective aluminum fluoride in the product is high; meanwhile, the heat preservation time and the cooling rate are further controlled, so that aluminum fluoride grains generated by the reaction grow up, the obtained aluminum fluoride is good in flowability and can be well compatible with automatic discharging equipment of the current industrial aluminum electrolysis cell, and green and sustainable development of the electrolytic aluminum industry is achieved.

Description

technical field [0001] The invention relates to a method for treating fluorine-containing waste electrolyte, which belongs to the field of metallurgical solid waste recovery and treatment. Background technique [0002] Fluorine-containing waste electrolyte is one of the main solid wastes produced in the aluminum electrolysis process, which mainly comes from three aspects: one is the electrolyte taken out during the operation of the electrolytic cell to stabilize the molecular ratio; the other is the waste electrolyte mixed in the residual anode ; The third is the electrolyte mixed in the waste cathode when the tank is overhauled. It is understood that the production of 1 ton of aluminum often requires 20-30kg of various waste electrolytes. At present, in the industry, fluorine-containing waste electrolytes are generally disposed of in the form of stockpiling, which not only occupies the effective space of electrolytic aluminum enterprises, but also soluble fluorine may seep...

Claims

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Application Information

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IPC IPC(8): C01F7/50C01D5/06C01D5/00
CPCC01F7/50C01D5/06C01D5/004C01P2002/72C01P2004/01C01P2006/10
Inventor 吕晓军韩泽勋吴勇聪罗丽琼陈芳
Owner CENT SOUTH UNIV
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