Quasi-Equilibrium and Unsteady Mass Transfer of Low-Grade Bloedite in the Process of Static Water Dissolution

Abstract

Hydrometallurgical extraction and treatment of bloedite waste is one necessity for the sustainable development of sodium sulfate subtype salt lake mining areas, but the industrial dissolution of bloedite is not stable. One of the reasons for this is the unsteady mass transfer of dissolved electrolytes in water according to the diffusion model and static water dissolution experiment in this work. The diffusion behaviors of aqueous Na2SO4 and MgSO4 released from bloedite in water are similar, and their mass transfer coefficients decrease in a nonlinear manner as the diffusion process continues. Within 720 h of dissolution time, there is a quasi-steady-state quasi-linear stage of rapid increase in the solute concentration of leaching water, and a water depth of 20–40 mm is recommended as the optimal dissolution depth. Under such operating conditions, the amount of evaporated water required for salt production decreases in a quasi-linear manner with respect to dissolution time. However, after 720 h of dissolution and extraction time, the growth rate of brine concentration slows. The information provided by the model can be used in practice as a quantitative reference for bloedite recycling.

Keywords

• low-grade bloedite
• quasi-equilibrium
• unsteady mass transfer
• kinetic model
• dissolution