STUDY THE PARAMETERS AFFECTING THE PRODUCTION OF AI-Si ALLOYS FROM SODIUM FLUOSILICATE

Abstract

it can give a confidence to apply in a large scale. AI-Si alloys, and sodium aluminium fluorides were obtained by reacting molten pure aluminium with sodium fluosilicate. Sodium fluosilicate (Na2 SiF6) had been produced in Egyptian super­ phosphate fertilizer plants as a by-product from air pollution emissions. The produced Al-Si alloy is of high quality, containing up to 20% silicon and less than 0.12 % Iron. Preliminary experiments were carried out to study the factors affecting the dissolved silicon in the produced Al-Si alloys and sodium aluminium fluorides, these factors are : temperature, mixing speed, sodium fluosilicate to aluminium ratio, feeding rate and particle size. The results obtained were correlated to establish some empirical formulas representing the silicon content in the produced alloy as a function of each factor. An attempt in this study was made to characterize the rate controlling step of the reduction reacti.on between sodium fluosilicate and molten aluminium in order to achieve the optimum operating conditions, and also to suggest an specific mechanism:/s me tests were carried out on the "--" l._ ( produced Al-Si alloys as wells sodium fluosilicate. These tests '•/ are: chemical analysis, X-ray diffraction analysis, microscopic and

mechanical examination. The obtained results indicated that these products can be used directly in casting shops or aluminium reduction cells in aluminum smelters. The pilot and semi-industrial applications were carried out using the results of laboratory scale,