Basic Study On Extracting Alumina From Coal Fly Ash

Because of the lack of bauxite and with the knowledge of fly ash, extracting alumina from fly ash has becomeing the universal concern of domestic and international academics now. A new type high alumina fly ash appear in the midwest of mongolia in our country, which alumina level as high as fifty percent or so,the alumina content is the equivalent of which in the intermediate bauxite. So, today,as the decline of alumina resources, to the research of the fly ash will gradually improve the status of the resources scarce. And this aticle has using the microwave alkali in the high alumina fly ash to diatill the useful resources as silicon dioxide and alumina and so on.The comprehensive using of multisubject of theoretical knowledge such as coalfield geology,geochemistry, mineralogy and the physical chemistry and so on. From analysis the conglobation and the origins of material of the high alumina fly ash, to reserch mongolia jungar coalfield late paleozoic bituminous coal which is the origin of the high alumina fly ash. We also find that the fly ash mainly from the kao linite and thin boehmite which contained in the coal, and the particular geological and geochemical condicition determined the formation of such minerals; the research on microstructure, distribution of some major and chemical composition in the high aluminium fly ash indicates that this high alumina fly ash is a kind of valuable regenerative mineral resources,apart from alumina,which is also enriched in mullite crystallite. According to such characteristics of the fly ash, the brief technical route of cooperatively extracting alumina was determined as follows:first,activating the alumina,this aticle has comparing the microwave activation and mechanical activation and the two ways to cooperative. Then in the condition of microwave with sodium hydroxide for high aluminium fly ash to conducting low-temperature desiliconizing to enhance ratio of silicate to aluminium of fly ash. Then using sintering process of soda lime extracting alumina from desiliconized fly ash. Got the physical chemistry process and terms from desiliconized of high fly ash and the disting of alumina via orthogonal test, and it shows as follwings:The best activated conditions for fly ash is microwave radiation for30minutes and fine grinding it until particle size320have81%. The optimized conditions of desiliconlizatiomconcentration of NaOH,2.5mol/L, mass ratio of liquid to solid,40and reaction time35minutes. According to the best reaction, and that the extraction rate of silicon up to38.2%. According to the conditions mentioned above, and with the best Ca/Si2.2to alkaline lime sintering that the extraction rate of alumina was reach90%.