FEED PROCESSING FOR IMPROVED ALUMINA PROCESS PERFORMANCE

摘要

A process is disclosed for the treatment of an alumina process feedstock pri or to transferring the treated feedstock to an alumina process for extracting refined alumina from the treated feedstock. The treatment process includes: (a) heating the alumina process feedstock to a temperature of 400 .degree.C to 650 .degree.C by direct contact with combustion gas, and (b) cooling the heated feedstock to a temperature at whi ch it can be handled and fed to the alumina process. The treatment process also includes controlling the contact time of the alumina process feedstock at temperatures in step (a) to ensure decomposition of trihydrate alumina and monohydrate alumina. The process also includes: (i) limiting the maximum temperature of incoming gas to a stage of the proce ss in which the alumina process feedstock reaches the above temperature range of 400 to 650 .degree.C (hereinafter referred to as "the highest temperature stage"), and/or (ii) limiting the heat input into the highest temperature stage by ensuring that the main thermal load associated with thermal dehydration of the alumina process feedstock is taken up in earlier stage or stages into which combustion gas, at a temperature above that of the inlet gases of the highest temperature stage, is added.