Avaliação do sistema de alimentação de alumina no processo hall-héroult na alumar.

Abstract

Aluminum is one of the most versatile and is highly abundant in the earth's crust. The principal form of obtaining it is by Hali-Heroult process through dissolution of alumina in an electrolytic cell (pot) containing an electrolyte of fused cryolite (3NaF.AlF3) and additives at a temperature of about 960°C, with passage of electric current. One of the principal parameters of this process is the percentage of alumina in the electrolytic bath of the reduction cells. The difficulty in monotoring the percentage is because of inexistence of a method capable of continuos measurement of alumina amount in the bath. Behavior of two different alumina feeding control programs (TRACK and QLC) furnishing informations on the influence of the controls in relation to the bath temperature and to the operational behavior, identifying possibilities of improvements, proposing changes for their viability, in electrolytic cells at Alumar (Consorcio de Aluminio do Maranhao), were studied. From the results obtained, some suggestions were proposed to reduce the impact of the feeding control systems (TRACK and QLC), so that to make them more efficient.