THE REMOVAL OF SULPHUR COMPOUNDS IN SODA-LIME SINTERING PROCESS FOR PRODUCTION OF ALUMINA

Sodium sulphate is formed from pyrite and other sulphur compounds in theraw materials, such as bauxite and limestone, and in fuels, such as coal and fueloil employed during sintering, causing higher soda losses of the process and givingtrouble to a number of operations, for instance, the ring-formation in the ro-tary kilns. The addition of anthracite, as a reducing agent to the raw mix for thekiln-feed, will reduce most of the sulphate into ferrous sulphide, which wouldeventually be removed from the process with red mud. This method has been suc-cessfully employed in alumina plants of soda-lime sintering process and Bayersintering combination process in China since 1961. Plant operating results as wellas experimental data, together with brief discussion are presented.