Abstract
Chromium slag is a solid waste of chromium salt production, which contains highly toxic Cr(VI) and significant amounts of valuable metals, such as Fe and Cr. Recycling chromium slag as a raw sintering material in sintering-ironmaking processes can simultaneously reduce toxic Cr(VI) and recover valuable metals. A micro-sintering experiment, compressive strength test, microhardness test, and first-principles calculation are performed to investigate the influence of Cr(2)O(3) on the sintering microstructure and mechanical properties of the silico-ferrite of calcium and aluminum (SFCA) in order to understand the basis of the sintering process with chromium slag addition. The results show that the microstructure of SFCA changes from blocky to interwoven, with further increasing Cr(2)O(3) content from 0 wt% to 3 wt%, and transforms to blocky with Cr(2)O(3) content increasing to 5 wt%. Cr(2)O(3) reacts with Fe(2)O(3) to form (Fe(1-x)Cr(x))(2)O(3) (0 ≤ x ≤ 1), which participates in forming SFCA. With the increase in Cr doping concentrations, the hardness of SFCA first decreases and then increases, and the toughness increases. When Cr(2)O(3) content increases from 0 wt% to 3 wt%, the SFCA microhardness decreases and the compressive strength of the sintered sample increases. Further increasing Cr(2)O(3) contents to 5 wt%, the SFCA microhardness increases, and the compressive strength of sintered sample decreases.