Direct Roasting Technology And Mechanism Of Gold Ore Concentrate High Sulfur And Iron

As a member of the precious metals,gold has played a pivotal role in history.The so-called“Temporary Gold and Flourishing age of Jade”have caused gold production in gold mines to receive widespread attention.In the long history,gold production has increased.The gold roasting method has also changed along with the gradual reformation from the early group selection method and the mercury amalgamation method to the current cyanide leaching method.The cyanation method is a method in which an aqueous solution of an alkali metal cyanide is used as a solvent to leach gold from a gold ore and then extract gold from the leachate.Since the first cyanide leaching in 1887,the cyanidation process has been rapidly applied throughout the world.The cyanide process is widely used due to its low cost and high recovery.However,with the continuous increase of gold production,gold-rich ore gradually decreases.To maintain the production of gold,it is difficult to handle gold ore as an important source of gold.Difficult to deal with gold because of the existence of gold is different from the rich gold ore,resulting in low recovery of cyanide leaching gold.Causing serious environmental threats.In order to solve the above problems and combine the trapping phenomenon of the base metals in the pyrometallurgical melting,a direct roasting process was proposed.This process utilizes the enrichment effect of the matte phase in the smelting process to trap the gold.During the experiment,the high-sulphur high-speed iron gold concentrate provided by the Hexi Gold Mine in Yantai was used as the raw material.Thermodynamic analysis was first performed to explore possible chemical reactions and the temperature of the solid phase reaction in refractory gold ore,and then based on the refractory gold ore.The main elemental content of the CaO-SiO₂-FeO ternary phase diagram is theoretically analyzed,and the phase change of the substance in the ternary system at different temperatures is investigated through thermogravimetric analysis and XRD spectrogram analysis.Finally,the refractory gold deposit is directly smelted.Through the choice of additives,the choice of roasting temperature and time,and the choice of the ratio of the additive to the additive to determine the direct yield of rhodium relative to gold during the direct smelting process.In the course of the experiment,the thermodynamic analysis of possible chemical reactions in the gold mine was first carried out,and the specific temperature of each reaction was determined by thermodynamic calculation to provide a theoretical basis for the subsequent experimental program;in the course of phase diagram analysis,The specific location of the slag in the phase diagram was determined by calculating the contents of SiO₂,FeO,and CaO in the slag phase,and then determined by the control variable method to determine SiO₂ 34.9%,FeO 27.37%,and CaO 19.5%.Each group of group A,B and C is divided into five equal parts for experiment.Through the differential thermal analysis and metallographic analysis of the three groups of samples during the experiment,the equal proportion rule in the phase diagram can be used to infer the appropriate reduction of CaO in simulated slag.SiO₂ can reduce the melting point of the sample to some extent.Increasing FeO/SiO₂ can also reduce the melting point of the sample to a certain extent.The experiment firstly carried out additive selection,and selected Na₂CO₃,Fe₂O₃,and Fe₂O₃+CaO as additives to perform roasting tests at different temperatures of 1000°C,1100°C,and 1200°C.The direct yield of Fe₂O₃+CaO as an additive at 1200°C was85.06%;Fe₂O₃ and CaO as additives at 1100°C,1150°C,1200°C,1250°C,1300°C temperature calcination,the direct yield of gold at 1250°C when the 89.45%;in the1250°C conditions selected for 10min,30min,50min,and 70min are the holding times,and the vertical yield of gold is the highest when the holding time is 30min.According to the proportional relationship between FeO and CaO in the phase diagram,the ratios of FeO and SiO₂ are selected to be 1.1,1.2,1.3,and 1.4.The roasting test with SiO₂ ratios of 0.2,0.4,0.6,and 0.8 determined the best experimental results when the ratio of FeO and CaO was 1.3 and the ratio of CaO and SiO₂ was 0.4 through the analysis of the gold content and the calculation of the straight yield..Therefore,the best technological conditions for the direct smelting of refractory gold ore are as follows:calcination temperature 1250°C.,holding time 30 min,FeO/CaO 1.3,and CaO/SiO₂ 0.4.Under the optimal conditions,the straight gold yield of refractory gold was 89.45%,and the gold content in the slag phase was 4.13 g/t.The experimental results show that the high-sulfur and high-iron refractory gold concentrate can realize the effective enrichment of gold under the direct smelting process conditions.This method is feasible and can provide new guidance for the treatment of difficult-to-treat gold mines.