LAUSR

Abstract For improving the consolidation strength of chromite pellets with high Cr/Fe ratio of 2.55, industrial waste silica powder was innovatively applied as the additive to facilitate the pellet consolidation. Results showed that with the dosage of silica powder increasing, the drop number of green balls was enhanced obviously, while the compressive strength was increased initially and then dropped. Quality indexes of green balls were considerably improved with keeping the dosage of silica powder within 2–4%. When 4% silica powder was added, the compressive strength of both preheated and roasted pellets achieved an evident improvement from 231 N/P and 790 N/P to 431 N/P and 1298 N/P, respectively. The preheating and roasting temperatures decreased from 1100 °C and 1350 °C to 1075 °C and 1300 °C, respectively, which met the normal operation temperature range of grate-kiln process. The revealed mechanism of silica powder strengthening pellets consolidation consisted of three aspects: new minerals formed via solid phase reaction between silica powder and chromite facilitated the minerals crystallization; a small amount of liquid phase formed during roasting process facilitated the ion diffusion; the intertwined structure was formed between liquid phase and chromite particles. The research findings not only provide theoretical guidance to produce high quality chromite pellets for submerged arc furnace, but put industrial waste into value-added use, which exhibits great application prospect.