Economic Optimization of Rare Earth Element Leaching Kinetics from Phosphogypsum with Sulfuric Acid

Frequently optimizations of chemical processes are presented in terms of the maximization of fractional conversion, but the primary concern when implementing a process is much more likely to be the economic viability. These are distinct optima that tend to occur at very different points. It was the purpose of this paper to integrate leaching experimental data with cost analysis to arrive upon economically optimized leaching conditions for the recovery of rare earth elements from phosphogypsum, a water phosphate byproduct. The variables under consideration were the number of leaching reactors and the residence time of each reactor. The modeling results indicated that the optimum residence time was 270 minutes and that the optimum number of stages was one.