Study On Preparation Of Ultra-fine Aluminium Silicate And Alumina Whiskers From Bentonite

The storage of bentonite is abundance and the distribution is very wide in ourcountry. However, the present products of bentonite are too many low-gradevarieties, the waster of resources is serious and the benefit is poor. Development ofhigh value-added products is the direction of future development of bentonite. In thisthesis, ultra-fine aluminum silicate and aluminum oxide whiskers were producedfrom the bentonite. The production process equipment types were selected, theeconomic benefits were calculated and the environmental protection was analyzed.The product structure and morphology were characterized by XRD, SEM, TG,FT-IR. The main results were as follows:(1) The results showed that the leaching rate of Al2O3in bentonite was morethan96%under the optimum acid leaching conditions. The removal ratio of ironwas more than95%at optimum purification conditions and the leaching ratio ofSiO2can reach above98%under the optimum alkali leaching conditions.(2) In the optimum conditions determined by the production of ultra-finealuminum silicate experiment, the contents of Al2O3and SiO2in the product wererespectively11.19%and81.42%. The main component contents met the Q/GSH01-2009enterprise standard requirements. The recovery ratio of SiO2in montmorillo-nite was more than85%.(3) Alumina whiskers precursors with a diameter of about500nm, a length ofabout15μm and the aspect ratio about30were prepared in optimal conditions.Different crystalline of alumina whiskers with a length of about12μm, a diameterof about400nm and a length/diameter about30were obtained after calcined at900~1100℃for1h. The chemical analysis results showed that the main componentcontents of alumina whiskers prepared in the experiment were accorded with theAO-3products of alumina national standards (GB/T24487-2009). In the preparationtechnology of ultra-fine aluminum silicate and alumina whiskers from bentonite,the total recovery rate of Al2O3is onto90%.(4) Economic benefit estimation results showed that it had a good economicbenefit to prepare ultra-fine aluminium silicate and slumina whiskers frombentonite. The environmental analysis results showed that it nearly had no wasteproduction in the productive process and it was a cleaner process.