Research On The Transformation Of Sulfur In The Rich-Oxygen Leaching Process For Sulfide Concentrates

As an important process of processing the sulfide concentrates,the technology of rich oxygen pressure leaching has lots of benefits,such as short process,less "three wastes"emissions,low cost,high leaching rate of Zn,and S output in elemental form etc.With the improvement of the environmental requirements of smelting enterprises and the increase of the treatment of the poor and complex mine,the use of rich oxygen pressure leaching technology for the treatment of zinc sulfide concentrates is more meaningful.At present,The pressure hydrometallurgy in our country is still at its preliminary stage,there are many problems to be solved,especially in the leaching process of sulfur transformation and self balance problems.In this paper,a new method for the self-equilibrium of sulfur and sulphuric acid in the process of zinc sulfide leaching was proposed.The thermodynamics in the process of pressure leaching zinc sulfide concentrate was calculated,and the influence of acid leaching conditions on the leaching properties of zinc sulfide concentrate was investigated,sulphur leaching dynamics and the characteristics of sulfur from the balance and other aspects were studied.The results are as follows:Firstly,through thermodynamic calculation,determine the zinc-S-H2O reaction equation,Each ?GT0 of material in the system was calculated under the temperature from 110-160 ?.According to the results of thermodynamic calculation,under the condition of the temperature range is 110-160,oxygen partial pressure is 1.0MPa and ionic activity is 1,the?-pH graphs were plotted.The results show that the area of Zn2+ and S was basically unchanged with the increase of temperature,and the precipitation potential increased gradually.Secondly,the factors of particle size,temperature,sulfuric acid concentration,leaching time,oxygen partial pressure,solid-liquid ratio,agitation rate and additive amount on rich-oxygen leaching process of Zinc Sulfide Concentrate were studied,based on the s-pH figures of ZnS-H2O system.The results indicated that at the temperature of 150?,leaching time of 90min,oxygen partial pressure of 1.0MPa,liquird to solid ratio of 16:1,stirring rate of 600rpm,particle size of-0.075?+0.055mm and initial acid concentration of 150g/L,and the leaching rate of zinc is about 94.23%,the conversion rate of S is about 88.51%.Thirdly,The shrinking unreacted core model was used to study the kinetics of the sulfur production process,the results are as follows:The chemical reaction is the control step in the leaching process,The reaction activation energy is 53.50kJ/mol.The sulfur conversion rate of the pressurized leaching process of zinc sulfide concentrate increases with the decreasing of the particle size,and the kinetic equation of the different particle size is:The sulfur conversion rate of the pressure leaching process of zinc sulfide concentrate increases with the increase of rotational speed,and when greater than 600r/min,the speed increases almost no effect on sulfur transformation.During the pressure leaching of zinc sulfide concentrate,the temperature has a significant effect on the sulfur conversion,with the increase of temperature,the sulfur conversion corresponding increase,the kinetics equations of different temperatures is:In the process of pressure leaching of zinc sulfide concentrate,the sulfur conversion of oxygen partial pressure has a remarkable effect,with the increase of oxygen partial pressure,the sulfur conversion corresponding increase,the kinetics equations of oxygen partial pressure is:ln k=1.02151np-5.60079Forth,The sulfur self equilibrium was analyzed by the orthogonal experiment and the single factor experiment,The results showed that when calcium lignosulphonate was not added,under different conditions,oxidation rate of sulfur is less and discrepancy are also small,the order of the primary and secondary is:the reaction temperature of initial acidity>liquid to solid ratio>reaction time>oxygen partial pressure.After adding calcium lignosulphonate,temperature became the main factors of sulfur to sulfuric acid,when transformation temperature greater than 170 ?,sulfur to sulfuric acid conversion efficiency is 5.3%or more.