Low Carbon and High Efficient Utilization of Zinc-bearing Dust in Iron & Steel Industry by Rotary Kiln Process

Abstract

More than 50 million tons per year of zinc-bearing dust with large amounts of zinc and iron resources is produced by iron and steel smelting in China, which is classified as hazardous solid waste. The zinc-bearing dust is an important secondary resource, in which the zinc and iron can be recycled as raw materials for the iron and zinc industries after separating them. Rotary kiln reduction is one of the main methods for separating zinc and iron from zinc-bearing dust. In this study, the 5 mm composite pellets containing zinc-bearing dust is prepared by forced disturbed pelleting as reduction charge. The rotary kiln system with controllable temperature field and atmosphere field by multi-point quantitative air suppling is used as the main equipment of reduction. This technology can realize the treatment of raw materials with high iron and zinc content in rotary kiln, but also can effectively improve the production efficiency and the quality of zinc oxide powder, reduce the kiln-ringing. Compared with the conventional rotary kiln method, the processing capacity of zinc-bearing dust increase by 30%. The zinc removal ratio reaches 95% and the ZnO content of zinc oxide powder is 53.93 wt.%. The TFe content and ZnO content of reduction product are 60.56 wt.% and 0.25%, respectively. The annual operation ratio of zinc-iron separation by rotary kiln with zinc-bearing dust is 92%. The metallization rate of reduction product is controllable. The reduction product with metallization rate of 65.97% can be used as a sintering raw material, and the comprehensive energy consumption is 187kgce/t. The reduction product with metallization rate of 88% can 1 be used as a converter steelmaking raw material, and the comprehensive energy consumption is 253.1kgce/t.