| In order to reduce the influence of highly toxic sodium cyanide on the en-vironment and the safety hazard of gold leaching process,environmental agent was used to leaching the roasted product of refractory gold concentrate.The chemical composition of the roasted product of refractory gold concentrate,the copper leaching of roasted product of refractory gold concentrate,agitation lea-ching,kinetic research,activated carbon adsorbing in the solution of environm-ental agents were carried out.The leaching process of environmental agent and adsorption of activated carbon were studied systematically.Firstly,the effect of the roasted product of refractory gold concentrate con-taining 0.98%Cu on the gold leaching rate were carried out.It is clarified th-at the copper in the roasted product of refractory gold concentrate can signify-cantly reduce the gold leaching rate of sodium cyanide or environmental agents.The experiments preliminary indicate that the properties of the environmental protection agents are better than that of sodium cyanide.Secondly,the copper leaching experiments of the roasted product were car-ried out.The effects of initial acidity of sulfuric acid,the ratio of liquid to so-lid,the leaching temperature,the leaching time,the stirring speed and the stre-ngthening leaching methods were investigated.The influence of various factors on the copper leaching rate is described.The reasons for the hard leaching copper are analyzed.The optimum conditions of acid leaching copper were obt-ained.The optimum conditions are 0.1 mol/L of the sulfuric acid,70 ~oC of the temperature,4:1 of the liquid-to-solid ratio,3 h of the leaching time and300 r/min of the stirring speed.The copper leaching rate in the optimum cond-itions is 82.44%and the copper in slag after copper leaching is 0.198%.Thirdly,the leaching experiments of Au and Ag after the copper leaching were carried out.The effects of the concentrate of the environmental agent,pH,the ratio of liquid to solid,the leaching temperature,the leaching time,the ty pe of oxidant,the stirring speed and the strengthening leaching methods were investigated.The influence of various factors on the leaching rate of gold and silver is described.The reasons for the hard leaching gold and silver are anal yzed.The optimum conditions of leaching gold and silver were obtained.The optimum conditions are 5 g/L of the environmental agents,11 of the pH,5:1of the liquid-to-solid rate,2 h of the leaching time,25~30?of the leaching te mperature and 300 r/min of the stirring speed.The gold leaching rate in the o ptimum conditions is 92.68%and the silver leaching rate is 85.41%.Fourthly,the kinetics of leaching gold was studied.The diffusion control of the leaching is clarified.The method of raising the concentration of environ-mental agents and the temperature appropriately is put proposed.Finally,the absorbing experiments of Au and Ag by activated carbon and the experiments of the reusing absorbing solution were carried out.The effects of the particle size of activated carbon,the dosage of activated carbon,pH,temperature and the absorbing time were investigated.The influence of various factors on the adsorbing rate of gold and silver is clarified systematically.Moreover,the experiments of the reuse of the absorbing solution were investig-ated.The experiments on the leaching of gold and silver by environmental agen-t were carried out.The optimized process parameters are obtained.The results showed that the main indexes of environmental agent in the process of leachi-ng gold and silver are better than those of sodium cyanide.Sodium cyanide can be substituted in actual production.Furthermore,the process of environmen tal agents is the same as that of the highly toxic sodium cyanide.The differen-ce of the two process is only some of the parameters.Thus,the cost of techn-ology improvement is reduced. |
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