Research On The Behavior Of Sulfur And Iron In Series-Combination Sintering Process

ABSTRACT:The usage of sulfur-containing bauxite has brought a lot of adverse effects to Bayer process of alumina production,such as corrosion of the equipment, reducing the seed decomposition rate, contamination of the product,in which, contamination of the product affects most. Alumina plants can use series process to recover alumina in the Bayer red mud,therefore, the accumulation of sulfur in Bayer process will enter series process,which will contaminate the solution of sintering process. So research on the behavior of sulfur and iron in the sintering process for alumina production is necessary.In order to reduce the sulfur content in the system, adding coal is used in the process of sintering.The behaviors of sulfur and iron in sintering process were studied. Research showed that higher temperature and longer time could make more sulfur into the solution.Increased reduction was beneficial to reduce the content of S2-and Fe in the solution.A study was carried out on sintering product material composition. The results showed that (1) undering reductive atmosphere at1100℃, the essential products of the sintering reaction between sulfur and iron are FeS and NaFeS2(sodium iron sulfide);(2)NaFeS2becomes NaFeS2·2H2O during the alumina digestion.The effect of removal of iron in the sodium aluminate solution by using sodium N,N-dimethyl dithiocarbamate (SDD) were studied. Research showed that the content of iron in solution could be reduced from11.48mg/L to3.78mg/L at60℃when the dose of SDD was125mg/L.