Method for harmless disposal and recycling of aluminum ash

Abstract

The invention discloses a method for harmless disposal and recycling of aluminum ash. The method comprises steps of raw material water immersion nitrogen and chlorine removal, calcination fluorine removal, alkali fusion sintering, sintering material dissolving-out and purifying impurity removal. Aluminum ash generated in metal aluminum smelting process is employed as a raw material, after metal aluminum is recycled through secondary processing, nitrides are removed through water immersion, fluorides are removed through calcinations, alkali fusion sintering is carried out, the sintering materials are dissolved out, impurities are removed through a sodium aluminate solution, the processed aluminum ash is employed as a raw material for producing sand-shaped aluminum oxide. Ammonia gas generated in the aluminum ash harmless disposal process can be employed as an ammonium production raw material, a chlorination liquid generated can be employed as a chlorate production raw material, and silicon fluoride gas generated in the calcination process is absorbed by an aqueous solution. The method is simple and practical, environmental protection benefits are high, the production efficiency is high, the device investment is low, and energy consumption is low. Harmless and recycling disposal of hazardous wastes can be achieved. The obtained product can be applied in practical production.

Description

technical field [0001] The invention belongs to the technical field of metallurgy and environmental protection, and specifically relates to a method for harmlessly treating hazardous waste aluminum ash and removing impurities through alkali sintering treatment as a raw material for producing sandy alumina. Background technique [0002] Aluminum ash is produced in the production process of aluminum melting such as electrolysis of primary aluminum, casting aluminum products, and aluminum alloy refining. The aluminum content in aluminum ash ranges from 10% to 80%, and the aluminum in it accounts for about 1% to 12% of the total loss in the process of aluminum production and use. It mainly contains aluminum dross, nitrides, NaCl, KCl, and fluorides. , a mixture of alumina and aluminum, etc. According to the forecast of authoritative research institutes, China will produce 6-8.5 million tons of aluminum ash every year, and the trend is increasing year by year. It can be seen th...

AI Technical Summary

Problems solved by technology

One is that the aluminum ash is returned to the aluminum electrolysis process after simple treatment to produce metal aluminum again. This method seems feasible, but most of the aluminum in the aluminum ash is α-Al with a good crystal lattice. 2 o 3 , its activity is very poor. Although it can be dissolved by the electrolyte during the electrolysis process, its ionization requires more energy than directly adding aluminum electrolysis raw materials, which will inevitably cause problems such as increased energy consumption in the aluminum electrolysis process and increased cell voltage.

Another route is to remove impurities after the aluminum ash is treated by the acid method or alkali method, and then produce chemical products such as aluminum trichloride and aluminum sulfate. This type of method has great development prospects, but the use of aluminum ash to produce such chemical products The product is still in the research stage, has not yet achieved industrial scale production, and the production cost is higher than the cost of existing production methods

The third route is to use aluminum ash as a raw material for the production of building materials or refractory materials. This method is a very economical and comprehensive way to return aluminum ash, but its development is limited due to the presence of harmful elements such as fluorine and chlorine in aluminum ash.

The more important reason is that for a single aluminum electrolysis power plant, the amount of aluminum ash produced is relatively small. If they are built and processed separately, the cost will be high, but because aluminum ash is a hazardous waste, it is difficult to dispose of it. It is delivered to the factory for centralized treatment, so the aluminum ash is simply processed at a relatively low cost in a single aluminum electrolytic aluminum plant to achieve harmlessness. It is a promising route to be transported as a safe material to the factory for centralized resource utilization. , but there are no related intellectual property rights and literature reports. This is also an excellent method for aluminum gray-green economic resource processing, which has great significance and value

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