| As the gold concentrate grades gradually decline.The development and utilization of low-grade refractory gold concentrates has become the focus of research.In this paper,the fluoride salt pretreatment-cyanide process was used to pretreat the complex gold concentrate roasting acid leaching residue,and the optimal process conditions and reaction kinetics were explored.The immersion slag and fluorine in gold and silver were studied by means of EMPA and EDS.The occurrence state of salt pretreatment slag and cyanide slag was characterized,and the following conclusions were drawn:Firstly,the thermodynamic study of the leaching process of acidic fluoride salt system shows that the temperature is 298.15 K and the concentration of fluoride ion concentration is1 mol·L-1 when the concentration of the minerals such as quartz and hematite is large.Achieve better pretreatment results.Secondly,the experimental study on the treatment of complex gold concentrate roasting acid leaching slag by ammonium bisulfate-sulfuric acid system pretreatment-cyanide process was carried out.The effects of sulfuric acid concentration,ammonium hydrogen fluoride concentration,time and reaction temperature were investigated.The system described various factors.The leaching rate of gold and silver affects the law,and the optimal conditions are as follows:sulfuric acid 2.0 mol·L-1 ammonium hydrogen fluoride 1.5 mol·L-1,time 60 min,reaction temperature 40°C,liquid-solid ratio 5:1,stirring speed 300 rpm;under this condition,the removal rate of iron can reach 42.18%,while the removal rate of silicon is 24%,the leaching rate of gold is up to 97.63%,and the leaching rate of silver reaches 94.84%.The process of silver leaching process was optimized by Box-Benhnken response surface method,and the influence of various factors on silver leaching rate was compared.The optimum process conditions were optimized for the response equation:1.42 mol·L-1 NH4HF2,2.0mol·L-1 H2SO4,the reaction temperature was 40.76°C,and the reaction time was 90 min.Under this condition,the silver leaching rate was 94.84%.Thirdly,the kinetics of gold and silver leaching of fluoride salt pretreatment-cyanide leaching was investigated.The kinetic data accorded with the JMA model.The order n of gold in the Avrami equation is 0.646,and the order n of silver is 0.668.The apparent activation of gold The energy can be 19.15 kJ·mol-1,and the apparent activation energy of silver is 16.00kJ·mol-1.The pretreatment reaction of fluoride salt is controlled by internal diffusion.Finally,the phase change of the complex gold concentrate roasting acid leaching residue in the ammonium bisulfate-sulfuric acid system pretreatment-cyanide process was investigated.After SEM-EDS analysis of the ore,it was found that the oxide-encapsulated structure on the surface of the particles was once again destroyed,and the size and number of voids on the surface of the particles increased again.The gold and silver on the surface of the particles increased by an average of 1.29%and 0.35%,respectively.Combined with mineral MLA analysis,some natural gold or gold attached to lead ore can be found in the ore profile.The fluoride salt is inside the ore before pretreatment,and is treated at the edge of the section;further indicating that gold and silver are exposed on the surface of the ore.It is conducive to increasing the cyanidation extraction rate of gold and silver.The EMPA analysis of the minerals did not change much in the acid leaching-fluorine salt pretreatment-cyanide process.After the fluoride salt treatment,the gold and silver in the ore had obvious enrichment areas,and there were also The bright spot with higher silver content indicates that the fluoride salt pretreatment process can be well exposed to the particle surface,while the distribution of gold and silver in the cyanide slag is relatively dispersed,the content is not high,and the gold and silver in the ore have been leached. |
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