THEORETICAL ANALYSIS OF THE VELOCITY OF SIMULTANEOUS LEACHING OF MANY ELEMENTS.

A mathematical model for simulated leaching of various metals from a kind of ore was proposed. In the model, the reaction rate equations of leaching are expressed as functions of the concentration of the species in liquid and solid phases, and the concepts of effective diffusion in the solid phase are introduced in order to estimate effects of diffusion of the reaction rate. The theoretical results agreed with the experimental ones of leaching of nickel, copper, iron and other metals from manganese nodules with sulfuric acid. The reaction orders with respect to the concentrations of nickel and copper in the solid phase are second-order, respectively, and that with respect to the concentration of iron is first-order. The effective diffusion coefficient is independent of the particle size of the nodules. The value of activation energy of the effective diffusion coefficient is so small (about 2. 5 kcal/mol) that the effective diffusion process may be considered to be molecular diffusion in pores of solid phase. Also, the activation energies of the reaction rate constants with respect to nickel, copper and iron are 20. 8, 12. 8 and 20. 8 kcal/mol, respectively.