Effect Of Roasting On Quartz-gold Interaction And Its Mechanism

There commonly exist quartz and other gangue minerals in gold ores.Under the action of high temperature activation,gold likely interacts with quartz,which makes gold recovery more difficult.Therefore,it is of great significance to explore the effect of roasting on quartz and gold interaction and its mechanism.In this paper,quartz is taken as the research object,and the influence of roasting conditions and sulfide minerals(pyrite,chalcopyrite,galena and arsenopyrite)on the interaction between quartz and gold is investigated.The roasting conditions were 1,2,3 and 4 h and 600,650,700 and 750°C,roasting test of gold bearing samples.The cyanide leaching of gold-bearing roasted slag was carried out at a condition of 2.5 g,pulp concentration of 11.11%,leaching time of 8 h,rotating speed of 500 r/min,p H value of 11 and KCN concentration of 0.01 mol/L.The results show that the leaching rate of gold is 42.36% at room temperature and 21.43% at 750°C for 1 h,with the increase of temperature,the leaching rate of gold decreases.High temperature activated quartz,resulting in the interaction between quartz and gold,so gold is difficult to be leached by cyanide.When adding sulfide minerals,roasting may reduce the effect of sulphide minerals on gold,leading to the increase of gold leaching rate.When the interaction between quartz and gold is strong,the leaching rate of gold tends to decrease.The infrared spectrum analysis of gold bearing roasts shows that there is a vibration absorption peak of quartz and gold interaction at 667 cm-1.Under the conditions of 1,2,3 and 4 h and 600,650,700 and 750℃,the samples without gold were roasted.The gold cyanide adsorption experiments were carried out at a condition of roasted residue of 3 g,gold cyanide concentration of 120 mg/L,pulp concentration of 12.50%,stirring time of 30 min and rotating speed of 500 r/min.The concentration of gold in the supernatant after centrifugation was determined by atomic absorption spectrometry,and the solid was analyzed by infrared spectroscopy.At 650°C for 4 h,the gold cyanide was adsorbed by the cinder with the adsorption capacity of 0.085 mg/g and the adsorption rate of 12.54%,this shows that the adsorption of gold cyanide on quartz calcine is strong at this temperature.After adding sulfide minerals,the interaction between sulfide minerals and quartz occurs.When the interaction between minerals is stronger than the adsorption between quartz and gold cyanide,the adsorption amount and the adsorption rate of gold cyanide on the quartz roasting residue decrease.When the adsorption between quartz and gold cyanide is strong,the adsorption amount and the adsorption rate of gold cyanide on the quartz cinder increase.In the infrared spectrum,there is a vibration absorption peak of quartz and gold at 669 cm-1.Quantum chemical calculation of 700°C quartz and gold using CASTEP module in Materials Studio software.Under the condition of Fine convergence precision,the best exchange-correlation functional is GGA-WC,the best K-point is 3×2×2,and the best truncation energy is 440 e V.When the change range of surface energy of quartz is less than 0.05 J/m2,the optimum surface structure of quartz(101)is determined as 13.076 ? for atomic layer and 14 ? for vacuum layer.The adsorption models of relaxed quartz crystal with Au atom and Au(CN)2-under vacuum condition were established.It is concluded that Au atoms are bonded to Si-12 on the surface of quartz(101)and Au,N atoms in Au(CN)2-are bonded to Si-12 on the surface of quartz(101).The effect of the interaction between quartz and gold on gold leaching behavior was speculated and the bond between quartz and gold at high temperature was proved by experimental study,characterization analysis and simulation calculation.