Design of an advanced hydrometallurgy process for the intensified and optimized industrial recovery of scandium from bauxite residue

摘要

This study aims to the industrial scale development of Bauxite Residue leaching for Scandium recovery, by optimizing a hydrometallurgy method and taking account appropriate design concepts for process intensification. Approaching the design issue either by adapting arithmetic methods, or using related software, showed inconsistent convergence, which is caused by the process particularities and non-conventional characteristics (i.e., feed flow-rates dependent on reflux ratio, hybrid of continuous and intermittent processes, etc.). Seeking also for process economic viability, typical cost-based objective functions showed to deviate from optima with a real economic sense. To deal with both challenges, necessary modeling simplification for advanced Leaching with Mineral Acids (LMA) was made, coupled with commercial economics and profit-based objective functions. Under the design aspect, additional constraints were introduced for the Pregnant Leach Solution (PLS) that were arisen from the subsequent Resin ion eXchange (RX) and the avoiding of colloidal silica gel formation. The optimized leaching resulted to the highest possible: solids-to-liquid ratio; molarity for RX-complying PLS; and temperature for acceptable [Si] (e.g., SL = 33.3 %, C-FA = 0.31 M, T-L = 32 degrees C, P-L = 1 atm, N = 1.01, tau(L) <= 1 h). Also, the developed simulation model can have expanded application for different LMA cases, and the introduced economic evaluation method is suitable for the production of various internationally traded commodities.