Investigation of lime usage impacts on bauxite processability at ETI Aluminyum Plant

ETI Aluminyum A.Ş., the primary aluminium manufacturer of Turkey, is also one of the major integrated plants of the world capable of performing production from mining until end product. The alumina refinery was designed on a certain boehmitic bauxite quality basis. However, bauxite properties have changed over the years, resulting in the urgent need for process optimization to not only keep the refinery cost efficient, but also prevent serious bottlenecks in the near future. Lime can be used to overcome problems when using bauxites with specific and variable chemical and mineralogical characteristics. Although lime is extensively used when processing diasporic bauxites, the studies on boehmitic bauxites and the overall effects on the process are limited. In this paper, lime impact was investigated at all stages of the Bayer process including the effect on alumina quality, energy and raw material consumptions. The results showed significant improvements in the product quality as well as recordable savings on consumptions.