Research On Gold Leaching Process And Kinetics Of Refractory Gold Concentrate By3YL Wet Chlorination

A high-efficiency and low-toxicity gold leaching technology is studied in this paper for refractory gold concentrate using3YL chloride. After discussing pretreatment effectiveness on leaching process, reasonable suggestions on preconditioning are given here. In this paper, leaching process of refractory gold concentrate from Shandong province is discussed with three kinds of gold leaching reagents of3YL series. Three kinds of reagents are named J1, J2and J3. It is found that the gold leaching effect of J3is the best of all. Aiming at providing theory guide for further research and for adjusting parameters in industrial application, the leaching kinetics of J3is also discussed.The main parameters affecting gold leaching process are the concentration of3YL (leaching reagent), the concentration of NaCl (complexing reagent), temperature, acidity, stirring speed, solid-liquid ratio, leaching time, and sample size. The results show that the gold leaching efficiency of J3is the best of all, and the efficiency of J1is better than J2which does not work in gold leaching process. The optimal technological conditions of J1and J3are presented as follows:(1)The optimal initial concentration of J1and J3are2.5g/L and1.5g/L, respectively;(2)The optimal concentrations of NaCl are20%and8%when using J1and J3;(3)The optimal leaching temperature is30℃in two cases;(4)The acidity has small impact on leaching process when leaching process uses J1as leaching reagent, and the optimal concentration of H+is1mol/L when leaching process uses J3as leaching reagent;(5)The optimal stirring speed is500r/min in two cases;(6)The optimal solid-liquid ratio is1:6in two cases;(7)The optimal leaching time is2h in two cases;(8)The optimal granularity of gold Concentrate is D90≤25.15μm. The cost of J3is equal to cyanidation. But the supperiority of3YL Chloride is that the optimal leaching temperature is30℃, which nearly is the ordinary temperature. At the time, the gold leaching rate can reach97.89%wthin2h. However, cyanidation of refractory gold concentrate under ordinary temperature generally needs24h, with low gold leaching rate. So the leaching technology of by3YL chloride as leaching reagent is high efficienct at low temperature.The results of kinetics experiment when using J3as leaching reagent show that gold leaching process is controlled by interfacial reaction, and the activation energy (Ea) of leaching reaction is32.3kJ/mol. The reaction order of J3is1. The reaction order of Cl" is0.4876. The leaching kinetic equation can be interpreted as:1-(1-a)1/3=244.5rp[CJ3][Cl-]0.4876e-32300/RTt. To improve the leaching rate, we can (1)reduce the size of material particle;(2)improve the concentration of reaction agent;(3)increase the temperature;(4)reduce the sample density.In conclusion, the3YL chloride leaching method used here, has advantages as follows:(1)the leaching condition is simple;(2)the cost of the reagent is low;(3)the consumption of chemicals is small;(4)the gold leaching efficiency is high;(5)the toxicity is low. So it will have a widely industrial application prospect.