Feasibility analysis and discussion on treating red mud by HIsmelt reduction process
Red mud,as a solid waste produced by smelting bauxite,has a large production and low utilization rate,and the utilization rate of red mud in China is less than 10%.At present,most of the red mud is disposed of by pil-ing,which not only occupies a large amount of land resources,but also causes serious pollution to the environment,and the realization of multi-channel and large-scale recycling of red mud has become an urgent issue in China and even in the whole world.Through the law of conservation of matter and energy and combined with FactSage thermo-dynamic calculations and experimental verification,we analyzed the physical phase precipitation process and viscos-ity change rule of HIsmelt melt-reduced high iron red mud slag,obtained the addition ratio of HIsmelt melt-reduced treated red mud,and explored the feasibility of producing microcrystalline stone from HIsmelt melt-reduced treated red mud through the slag melting and reforming treatment.The results show that the addition of 30%(mass per-cent)or less of red mud under the normal smelting PB ore powder process conditions of HIsmelt has little effect on the slag viscosity and physical phase composition;melt reforming of slag by changing the slag alkalinity,the mass ratio of MgO/Al2O3,and the addition of diluent was obtained to obtain the decrease of viscosity with the increase of the slag alkalinity;at the time when the slag alkalinity is 1.2,and the MgO/Al2O3 mass ratio of about 0.6 slag vis-cosity lowest,but at the same time the slag w(SiO2)decrease,which shows that purely adjust the slag composition can improve the slag mobility,but can not meet the production of microcrystalline stone w(SiO2)content require-ments.On the basis of ensuring slag fluidity,w(SiO2)content in slag can be increased by adding CaF2.When CaF2 is added at 3%-5%,the slag reaches more than 40%,which can be considered as the raw material for the produc-tion of microcrystalline stone.
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