Study On Cyanide Recovery From Gold Leaching Solution By Ion Exchange Resin

As one of the most toxic pollution sources, cyanide effluents would not be allowed to drain because it not only polluted water resources but also lead to great waste of cyanide and valuable metals. This paper deals with an economical, effective ion exchange method to recover cyanide and valuable metals, provides process parameters for typical gold smelting plant domesticly.In this paper, 201 × 7 strong base anion exchange resin was selected as a suitable adsorptive material based on study of ion exchange capacities, adsorptive ratio and elution processes systematically. The kinetics and thermodynamics behaviors of ion exchanging were studied by static method;the adsorptive process in ion exhange column was studied by dynamic method, and then the parameters of ion exchange column were determined on the basis of experiments on factors such as flow rate, resin bed height. Furthermore, this paper explored a new feasible process of cyanide recovery,investigated the effect of time, concentration of H2SO4 and temperature on the elution of cyanide and zinc in the process of first stage elution, and discussed the effect of time,concentration of ammonia water, temperature and ultrasonic on the elution of copper in the second stage elution.The results showed that the kinetics of ion exchanging was controlled by Body liquid membrane diffusion, and the thermodynamics equilibrium accorded with Freundlish model. The thermodynamic parameters of adsorption were calculated: ΔH=1.473kJ·mol^-1,ΔG =-10.966kJ·mol^-1 ΔS =42.45J·mol^-1·K^-1. The better adsorption conditions were: the ratio of solution and resins was 20:1, the adsorptive time was 1.5h;H₂SO₄ elution conditions: 2.5%H₂SO₄, 1h;ammonia elution conditions: 8% NH₃ · H₂O, 2h. All experiments runned at room temprature.This process not only recovered the toxic cyanide and the valuable metallic elements in the wastewater effectively, but also improved the ratio of resource comprehensive utilization. If this process widely used, it will improve on the technical progress in gold industry, result in great economic effeciency, as well as social and environment benefit, which is good to realize circulate economy.