Advances in calcium-driven alkaline stabilization regulation of bauxite residue:A review
Bauxite residue is a strong alkaline solid waste discharged from alumina production,with a comprehensive utilization rate of less than 3%,and there is no economically feasible and large-scale disposal technique.The interfacial migration and transformation of alkaline mineral-aqueous solution leads to the pH rebound in the alkalinity regulation process generally,which is difficult to solve the strong alkaline problem of bauxite residue fundamentally,and how to suppress the slow-release behavior of alkaline minerals is the key to the stable regulatory of alkalinity within bauxite residue.This paper reviews the existence form of alkalinity in bauxite residue and its transformation rule,and discusses the alkalinity regulation theory of selective removal of free alkali and stabilization of alkali-containing minerals on the basis of in-depth analysis of the embedded state of alkali-bearing minerals in bauxite residue and their dissolution characteristics.Moreover,the Ca-driven stable regulatory of alkalinity within bauxite residue by gypsum was analyzed comprehensively,and the evolution characteristics and rules of alkali-containing minerals in the process of long-term stable regulation of bauxite residue alkalinity were further elucidated.Finally,the main research directions for the stability regulation of bauxite residue alkalinity to provide new strategies for achieving ecological rehabilitation in bauxite residue disposal areas were proposed.
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