Estudo de adsorção de fluoreto de hidrogênio num reator de tratamento de gases no processo industrial de eletrólise do alumínio.

Abstract

In the aluminum electrolysis process there is fluoride gases generation that it's recovered in the treatment systems in the smelter. This recovery has environmental and economic character. The fluoride is mainly noxious to the environment the vegetation and to treat it means to preserve the vegetable species. Economically it is viable the treatment due to the reduction in the aluminum fluoride (AIF3) consumption that is added to the process for chemical balance of the eletrolitical bath. The fluoride recovered of the gases is absorved in the alumina that later will be reduced in metal. The fluoride treatment in Alumar happens in the fluid bed reactors that operate with alumina (AI2O3). These reactors are operated in continue flow where are control the gas flow in the reactor entrance and the alumina volume in the bed. The alumina discharged of the reactor is sampling and analyzed, and one of the main parameters measurement is A I F 3 percent retained in the alumina that should be between 2,5 and 3,5 percent. The time that the alumina stay in the reactor bed has also impact in AIF3 percent in the alumina and this time is controlled by the reactor feeding rate. In this work the behavior will be evaluated of the A1F3 percent in the alumina, operating the reactor varying the conditions of bed level, gas flow and alumina feeding rate. The intention is to identify the possibility to operate the reactor in different conditions from the ones that commonly it is operated. So there is an expectation of could operate the system with a higher gas flow without for this it happens a too much increase of the A I F3 percent in the reacted alumina.