Mechanism And Simulation Study Of Zinc Leaching Slag Roasting In Rotary Kiln

Conventional leaching and hot acid leaching are the mainstream processes of wet zinc smelting in my country.The two are mainly the differences in iron removal processes.In recent years,with the national environmental protection policy and the management requirements of the hazardous waste list,the treatment of zinc smelting slag has become one of the important problems restricting the development of enterprises.Based on thermal acid leaching residue hazardous solid waste management and treatment technology and cost considerations,the conventional leaching process has a significant advantage in environmental protection,the current industry generally tends to use conventional leaching process.Rotary kiln fire treatment of leaching slag technology has the characteristics of mature technology,low construction cost,simple equipment,and good kiln slag arsenic holding capacity.It has obvious advantages in economy and environmental protection,and is the main technology for conventional zinc leaching slag treatment.Industrial practice shows that the rotary kiln roasting technology needs to be optimized and improved in terms of energy consumption and zinc and sulfur recovery rates.In this paper,on the basis of consulting literature and industrial production of rotary kiln,in order to achieve the purpose of optimizing the process conditions of rotary kiln volatilization,theoretical analysis and experimental research were carried out on the process of rotary kiln treatment of conventional leaching slag,and material balance and heat balance were carried out,Through the established mathematical model of rotary kiln to simulate it.（1）The thermodynamic calculation of the reduction of MeO in the zinc leaching residue and the thermal decomposition of MeSO₄ shows that the temperature of the kiln is controlled at 1000～1300℃,which can volatilize zinc and lead,and lead is preferentially volatilized over zinc.（2）X-ray diffraction and X-ray fluorescence spectroscopy system were used to analyze the phase and composition of zinc leaching slag.Based on the rotary kiln operating system,experiments were carried out on the moisture content of the zinc leaching slag and the roasting temperature increase method.The moisture content of zinc leaching slag is 21.71%.When the heating rate from 500 to 900℃is 6.8℃/min and the heating rate from 900 to 1150℃is 3.3℃/min,the volatilization rate of zinc and lead is the highest,and the volatilization rate is heated Speed effect.（3）The effects of roasting temperature,constant-temperature roasting time,coke ratio and raw material particle size on the volatilization rate of zinc and lead were investigated through condition experiments.The results showed that under the conditions of coke ratio=2:1 and zinc leach slag particle size<8mm,Constant temperature roasting at 1150℃for 120min,the volatilization rate of zinc and lead is high.（4）The phase analysis of the zinc leaching slag and kiln slag and the thermogravimetric analysis of the mixture show that the kiln slag mainly contains iron compounds,matte copper phase and SiO₂.Describe the material trend in each temperature range.（5）Based on the technological process and experimental data,the material balance and heat balance of the volatilization process of the rotary kiln are calculated,and the calculation of the structural parameters of the rotary kiln structure is completed.（6）Use the ANSYS software package to perform numerical simulation on the rotary kiln,put forward reasonable assumptions to simplify the rotary kiln model,and determine the control equations,turbulence models,and radiation models required in the simulation,draw the physical model of the rotary kiln,and establish the boundary conditions.The temperature and oxygen distribution in different working conditions in the kiln are simulated.