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Process for recovering waste liner of aluminium electrolyzer

An aluminum electrolytic cell and recycling method technology, applied in the direction of solid waste removal, waste treatment, etc., can solve the problems of small recycling volume, non-recycling, and high requirements for equipment technical conditions, and achieve the effect of large recycling volume and easy application.

Inactive Publication Date: 2004-03-10
赵隆昌 +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] 1. High-temperature hydrolysis method: This method is complex in process and requires high technical conditions for equipment. Although industrial experiments have achieved certain results, its promotion and application are limited by various conditions.
And this method will also use the graphite carbon in the waste tank liner as fuel to burn
Therefore, it is not a comprehensive recycling method
[0004] 2. Caustic soda solution leaching method: Although this method is currently used in some aluminum plants in Australia, this method can only recover 50% of the cryolite in the waste tank lining. Not only the recovery product is single, the recovery efficiency is low, and there are still a large Waste residue needs to be discharged
The quality of the product recovered by this method is poor, and its use is limited, so the recovery amount is small, so it has not been popularized and applied.

Method used

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Examples

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Effect test

Embodiment 1

[0016] Embodiment 1: Recycling dilute industrial hydrofluoric acid, producing filter residue raw materials for producing graphite powder, aluminum hydroxide, and aluminum oxide, and acid solution raw materials for producing various fluoride salts and sulfate products. Its specific steps are:

[0017] 1. Crushing and processing the dried waste lining of the aluminum electrolytic cell into -100 mesh powder for later use.

[0018] 2. Inject 90 kg of water into the acid hydrolysis tank with heat preservation facilities, and then add 310 kg of industrial concentrated sulfuric acid with a concentration of 98%. In the solution tank, start the agitator to stir evenly, and the substances in the acid solution tank undergo a chemical reaction.

[0019] 3. The gas produced by the reaction in the acidolysis tank is introduced into the rinsing absorption tower for repeated rinsing and absorption with water, and the discharged liquid is dilute industrial hydrofluoric acid.

[0020] 4. When...

Embodiment 2

[0021] Embodiment two: produce industrial sodium fluorosilicate and industrial sodium sulfate.

[0022] Combine the acidic filtrate in Example 1 and the acid water discharged from the rinsing filter residue, pour it into a neutralization tank, add 5 kg of burnt rice husk ash, then add 46 kg of light silica, stir slowly for 30 minutes, add 116 kilograms of sodium hydroxide (or add 154 kilograms of sodium carbonate) continue to stir for 20 minutes, after standing still for 30 minutes, remove the remaining rice husk ash on the surface of the liquid in the tank, and filter, and the filtrate is concentrated and crystallized, and industrial sodium sulfate 200 is recovered. kg, the filter residue is washed with water until PH = 6 and then dried, and 90 kg of industrial sodium fluorosilicate can be obtained.

Embodiment 3

[0023] Embodiment three: produce cryolite and industrial sodium sulfate.

[0024] The acidic filtrate in Example 1 and the acid hydration discharged by washing the filter residue are combined and injected into the neutralization tank, and after adding 210 kilograms of sodium hydroxide (or 252 kilograms of sodium carbonate) to stir and completely dissolve, then add 70 kilograms of anhydrous aluminum sulfate powder After stirring for 30 minutes, filter, rinse the filter residue with water until pH ≥ 5, then dry the filter residue to produce 110 kg of industrial sodium fluoroaluminate (ie cryolite). The filtrate was concentrated and crystallized, and 250 kg of industrial sodium sulfate was recovered.

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Abstract

A process for reclaiming the waste liner of aluminium electrolyzer includes charging water and concentrated sulfuriic and into acidolyzing tank, breaking off said waste liner, loading it in said acidolyzing tank, acidolyzing to generate gas, water spraying the gas to recover hydrofluoric acid, filtering to obtain dregs and filtrate, preparing graphite, industrial aluminium hydroxide and alumina from the dregs, and preparing fluorides and sulfates from the filtrate.

Description

technical field [0001] The invention is a method for comprehensively recovering valuable materials by using the waste inner lining of an aluminum electrolytic cell. Background technique [0002] At present, the industrial production of metal aluminum in the world is still dominated by molten salt electrolysis. The carbon lining of the aluminum electrolytic cell has been eroded and penetrated by the electrolyte for a long time. After about five years, it needs to be crushed and taken out for overhaul. On average, about 35kg of waste lining is produced for every ton of aluminum produced. A medium-sized aluminum plant with an annual output of 100,000 tons of aluminum will have 3,500 tons of waste lining of aluminum electrolytic cells to be disposed of every year. After analysis, the waste lining of the aluminum electrolytic cell contains 54% graphite carbon, 24% fluoride salt, and 22% aluminum oxide. Since there is no suitable treatment method, it can only be discharged as indu...

Claims

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Application Information

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IPC IPC(8): B09B3/00B09B5/00
CPCY02W30/20
Inventor 赵隆昌
Owner 赵隆昌
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