Study On The Harmless Treatment And Comprehensive Utilization Of Aluminum Ash

Aluminum ash is a kind of waste materials that be producted in the production process of aluminum smelting enterprises, such as electrolytic aluminium, aluminum-type cast, etc. The range of aluminum content is10%to80%, which accounts for the production of aluminum total loss of1%to12%. In2008, Ministry of Environmental Protection and the Development and Reform Commission has put slag and flammable scumming in the process of aluminum pyrometallurgical refining, salt slag and dross in the process of crude aluminum refining included in the "national List of Hazardous Wastes" and therefore cost-effective comprehensive recycling aluminum ash will have an important significance for aluminum industry in China.This paper studies the activity of aluminum ash at high-temperature cryolite soluble salt of, the method of harmless treatment, alkaline sintering modify the aluminum ash and dissolution of alumina in order to achieve the purpose of aluminum ash recycling. The main experimental content and research findings include the following three aspects:(1) Activity of aluminum ash. Respectively analyze activity of the main components of aluminum ash and sandy alumina in molten cryolite:the existence of a large number of α-Al2O3in aluminum ash, this α-Al2O3is different from the α-Al2O3is higher activity and more crystal defects in sandy alumina, the α-Al2O3in aluminum ash is crystal integrity, poorly defects and activity, dissolved in a molecular state in cryolite, it’s difficult to electrolytic ionization produce aluminium in electrolytic environment, it can not be raw material directly return to electrolytic aluminum produce aluminium.(2) Treatment of harmless aluminum ash. By washing, roasting and other methods to remove the main harmful elements nitrogen, chlorine, fluorine in aluminum ash, to get the bauxite requirements of trace impurity content from0.001%to0.2%, to achieve the purpose of harmless treatment. Nitrides were generated in the water immersion process can be used to collect equipment collected as raw material to produce ammonia compounds, chloride solution can be used as raw materials to produce chlorinated salt; silicon fluoride were volatilized in roasting process can be absorbed by alkali solution and available as raw material for a production of silicon fluoride, which can achieve a green aluminum ash utilization without efflux waste.(3) Sintering process recycling aluminum ash. Add NaOH into harmless aluminum ash and alkali sintering generate sodium salt, and water immersion, filtering the sodium salt to aluminum residual volume is about14%, aluminum the maximum leaching rate of94.35%much higher than the leaching rate of bauxite alumina production process of aluminum. Residue is red mud and mainly composed of calcium, magnesium, iron and other oxides no harm to the environment, can be stockpiled with other red mud which generated during the production of the alumina, the leaching solution after removal of iron, silicon, calcium impurities incorporated alumina digestion system to produce sandy alumina.