Research And Practice On The Technology Of Mixing And Disposing Lead And Silver Slag In "Tri-continuous Furnace" Lead-smelting System

The wet zinc refining process uses leaching slag(lead silver slag)produced by the hot acid leaching process and Yellow potassium bauxite slag,which is a dangerous solid waste.As the National Environmental Protection policy becomes more and more stringent,it is the only way to develop the comprehensive recovery and harmlessly treatment technology of environmental protection.The fire treatment technology of zinc leaching slag is superior to wet treatment technology in environmental protection and cost."tri-continuous furnace" melting pool smelting is one of the more advanced lead smelting techniques at present.It has significant advantages in improving product quality and production efficiency,reducing smelting energy consumption,and reducing environmental pollution.For lead-zinc joint production enterprises,it is one of the better methods to treat lead-zinc silver slag in lead smelting process.Based on the analysis of the research progress of lead smelting technology,the production technology of lead silver slag and its comprehensive recovery technology,this paper aims at the current production status of zinc smelting technology of a lead-zinc smelting enterprise in Shaanxi by the hot acid leaching and wet process and the "three-furnace".To carry out research and industrial practice on the treatment of lead silver slag with three continuous furnaces.1.Based on the study of thermodynamics,reaction mechanism,slag type and metallurgical equilibrium calculation of lead slag smelting process,the paper analyzes the technical feasibility of the mixed treatment of lead slag in the "three furnace" process.The smelting process route and related conditions were determined.2.On the basis of theoretical research,industrialized trials and production were carried out,and the continuous stable production conditions under the mixed lead-silver slag mode of the bottom-blown furnace were optimized,and the continuous stable production under the mixed lead-silver slag mode of the bottom-blown furnace was determined.The optimization conditions are:(1)Optimized batching process parameters: Pb grade of furnace pellets is 35%?40%,lead silver slag accounted for 25±2%,bituminous coal+sulphur blending amount is 0.4+0.4t/h,total sulfur is 15-17%,The moisture content is 9-12%,which can make the bottom blowing furnace reach a stable and efficient production state;(2)Under the above-mentioned batching process conditions,the optimum bottom blowing furnace smelting process parameters are: oxygen to material ratio: 110-120Nm~3/t.h,slag temperature of 1000-1070°C,iron to silicon ratio of 1.8-2.0,and calcium to silicon ratio of 0.5-0.8.3.This topic has carried out related technical transformations on the problems of environmental protection and operation of the bottom blowing furnace and the reduction furnace,and achieved practical results.4.Practice shows that the use of “tri-continuous furnace” mixed treatment of lead silver slag,in the bottom blowing furnace 22t/h feed volume production mode,the production of crude lead maintained at 4000t/month,lead silver slag mixing ratio of 25 %,achieved obvious economic benefits.The technology of “tri-continuous furnace” lead-smelting process for mixing lead-silver slag is feasible,has important application and promotion value.The future research of this technology will mainly focus on optimizing the equipment configuration of the "tri-continuous furnace " and the direction of treating lead silver slag alone by fire.