Improved methods for the design of multistage leaching systems

Abstract

Two powerful techniques are presented for the design of steady-state multistage leaching reactors. The first method, called the doubly integrated micromodel, consists of integrating the batch leaching rate of a single particle over distributions of both feed particle size and reactor residence time to arrive at the fraction unleached. This method is limited to systems with uniform solution conditions through-out.

In systems undergoing linear leaching when significant concentration or temperature differences develop between leaching stages, a new method, called the multiple convolution integral, may be applied. In addition to calculating the fraction unleached, this method also allows the numerical reconstruction of the particle size distribution between stages.

Each method is applied to several hypothetical leaching situations, and the numerical integration of both models by Gaussian quadrature is demonstrated. Also, a graphical technique is introduced for the design and optimization of complex leaching systems in conjunction with the multiple convolution integral.