Abstract
To release the environmental pressure from the massive discharge of bauxite residue (red mud), a novel recycling method of red mud in steel making process was investigated through high-temperature experiments and thermodynamic analysis. The results showed that after the reduction roasting of the carbon-bearing red mud pellets at 1100–1200 °C for 12–20 min, the metallic pellets were obtained with the metallization ratio of ≥88%. Then, the separation of slag and iron achieved from the metallic pellets at 1550 °C, after composition adjustment targeting the primary crystal region of the 12CaO·7Al2O3 phase. After iron removal and composition adjustment, the smelting-separation slag had good smelting performance and desulfurization capability, which meets the demand of sulfurization flux in steel making process. The pig iron quality meets the requirements of the high-quality raw material for steel making. In virtue of the huge scale and output of steel industry, the large-scale consumption and zero-waste recycling method of red mud was proposed, which comprised of the carbon-bearing red mud pellets roasting in the rotary hearth furnace and smelting separation in the electric arc furnace after composition adjustment.
Highlights
Red mud is a product term that refers to the industrial solid waste discharged during the Al2 O3 production from bauxite
Analysis result indicated red mud phase is mainly composed of α-goethite (α-FeO(OH)), hematite (Fe and bauxite the red mud phase is mainly composed of α-goethite (α-FeO(OH)), hematite
The results indicated that the melting point of the slag system directly affected the separation effect between the slag and the iron
Summary
Red mud is a product term that refers to the industrial solid waste discharged during the Al2 O3 production from bauxite. Approximately 140 million tons of red mud is generated worldwide [1]. By the end of 2015, the stock of red mud exceeded 2.7 × 109 tons [2]. The stacking of red mud occupies a substantial amount of land and consumes increased amounts of construction and maintenance costs of a yard. The dust formed by the naked red mud is dispersed in the wind and pollutes the atmosphere, which causes negative impacts on the survival of humans, animals and plants, polluting the ecological environment. The integrated utilized approach and method for red mud are mainly focused on the production of building materials [4,5,6], Minerals 2018, 8, 102; doi:10.3390/min8030102 www.mdpi.com/journal/minerals
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