Study On The Oxygen-enriched-chloride Roasting Technique And Kinetics Of Carbonaceous Silver Ore

A new pretreatment method named oxygen-enriched–chloride roasting method is proposed aimed at ore's high carbon-sulphur and low silver-gold extracting ratio.oxidation method and chlorination method aimed at sulphur and carbon respectively are combined in this method. The oxygen concentration is increased as well. Thus, the elimination ratio of carbon and sulphur reached the industrial production standard and the problem of high carbon-sulphur is solved successfully.In order to determine the optimum process conditions of roasting,we studied the oxygen-enriched–chloride roasting process parameters which include the mass fraction of chloride agent, temperature, the air-oxygen ratio on the effect of the removal of carbon and sulfur, the silver-gold extracting ratio and flue gas components. The optimum process conditions are as follows:the mass fraction of chloride agent is 10%; temperature is 550℃, air-oxygen ratio is 1:15. After roasting the extracting ratio of silver is increased from 35.5% to 92.2%, gold increased from 28% to 98.51%. The main components of flue gas are carbon dioxide, sulfur dioxide and chlorine, while there are little sulfur trioxide and hydrochloric gas.At the same time,we carried out a comparative experiment of oxygen-enriched–chloride roasting method, chloride roasting and oxidation roasting method. The main comparison are the removal of carbon and sulfur;the leaching effect of gold and silver. Meanwhile We compared the roasting times. The results of the comparison was that residual carbon mass fraction of oxygen-enriched–chloride roasting was 0.36%, the residual sulfur was 0.77%, extracting ratio of gold and silver was 98.51% and 92.2%; chloride roasting was 1.95% ,0.61% ,96.92% and 85.4%; oxidation roasting was 4.5%, 2.2% ,60.54% and 33.5%.The time of chloride roasting is much more two times of Oxygen-enriched–chloride roasting, and the time of oxidation roasting should be longer. Through the comparison experiment we can see that oxygen-enriched–chloride roasting method not only have very significant advantages of carbon and sulfur removal and the leaching of gold and silver, but also shorten the roasting time. Thus oxygen-enriched–chloride roasting method have obvious economic advantages in industrial production .We performed dynamic analysis of the roasting process through the relationship between the sulfur oxidation rate and the chlorinating agent mass fraction, temperature, air-oxygen ratio and particle size. The sulfur oxidation rate at 10 ~ 80% of the kinetic equation isτa=10~80%=0.80727(a1.357 d-0.2334 w0.4432 r0.3729e1483/T); sulfur oxidation rate at 90% of the kinetic equation isτa=90%=1.44 d-0.4234 e2934/T. Through analysis of dynamic equations we can see that the effect of roasting parameters on the roasting process, the kinetic equation of studing the Oxygen-enriched–chloride roasting can not only provide a theoretical basis and research model for the future, but also provide some guidance on the industrial production.we can see that oxygen-enriched–chloride roasting method solve the smelting problem of high carbon-sulfur complex silver ore successful. It has the feature of economy, high efficiency and simple operation. This method will be widely applied in industry.