OPTIMIZATION OF ELEMENTAL SULFUR UTILIZATION FOR ZINC REMOVAL FROM BAYER CYCLE
In the course of industrial processing of bauxites with high zinc content, Zn is removed from Bayer liquor by the addition of elemental sulfur supplied to the front of the process.
To increase production of sulfide ion (S2-) for binding zinc into insoluble compounds of sphalerite type and to decrease the negative impact of sulfur compounds having higher oxidation states (sulfides, thiosulfates, sulfites) on corrosion of the processing equipment, the change of the state of S-containing compounds in Bayer cycle was studied as a function of temperature, alkaline aluminate liquor compositions, holding time and other factors.
On the basis of the revealed dependences, the process was optimized, enabling a decrease in the specific consumption of elemental sulfur by 30-50% for purification of liquors from zinc, reducing corrosive aggressiveness of liquors and reducing losses of the caustic alkali in the form of sulfates, with improved operation monitoring of produced smelter grade alumina quality.