Research On Preparation Of Basic Glass From Lead Smelting Fume Slag

The slag in the reduction section of lead smelting is fumigated in the fuming furnace to produce the final waste slag—fuming slag.About 7100 tons of fuming slag are discharged for every 10000 tons of lead produced.China is the largest lead smelting country in the world,with lead output of 6.44 million tons in 2020,so a large amount of fuming slag will be produced every year.A small amount of heavy metals and other toxic and harmful components in the fuming residue pose a threat to the environment and have been listed in the national hazardous waste list.At present,there are mainly two kinds of harmless disposal methods for fuming residue:stacking and landfill after solidification;In addition,there are two ways of comprehensive utilization of resources:extracting a small amount of valuable metals and using them as infrastructure materials,but they still have the disadvantages of small utilization and potential environmental risks;Therefore,it is very important to solve the problem of full component resource utilization of fuming slag for eliminating environmental risk and effective utilization of resources.In view of the fact that the main components of lead smelting fuming slag except iron are basically the same as that of glass-ceramic,the comprehensive utilization of all components of fuming slag from a domestic lead smelting enterprise was studied by using the "Utilization according to quality" technology route,which including a series processes,such as carbo thermic reduction,melting separation,preparing glass-ceramic precursor—basic glass with separated slag.The FeO content of the fuming slag is about 44.77%.The other main component in the fuming slag are SiO2,CaO,Al2O3 and MgO.If 95.00%iron is removed from the fuming slag,the residual composition of the fuming slag is close to the basic glass composition of SiO2-CaO-Al2O3 or SiO2-CaO-MgO glass ceramics.The results show that the reduction of ferrous oxide mainly occurs in the range of 850℃～1050℃;The reduction of ZnO mainly occurs in the range of 1050℃～1250℃;When the temperature is above 1250℃,other components(such as silicon and manganese)will be reduced.The results show that the best conditions of reduction experiment are as follows:carbon Stoichiometric coefficient ratio is 1.4,reduction temperature is 1200℃,reduction time is 60min;Under these conditions,the metallization rate of iron reaches 92.94%- 94.04%,and the reduction volatilization rate of zinc reaches 99.04%～99.81%By holding the reduced fume slag at 1550℃ for 60 minutes,the iron and slag are separated from the reduced fume slag.The results show that the content of Fe in the reduced fuming slag is reduced to 0.90%and the removal rate of Fe is 97.42%.It shows that the secondary further reduction occurred in the melting separation process.The results show that a ferroalloy are obtained,which containing 6.55%Si,89.51%Fe and a small amount of impurities,such as Mn,Al,Cu,Cr.Taking diopside and feldspar as the target crystalline phasees to be precipitated,two basic glasses,1#and 2#were designed.Meanwhile,10.00%TiO2 nucleating agent was added to the melting separation slag as the formula of 3#basic glass.The content of slag in 1#basic glass,2#basic glass and 3#basic glass were 63.10%,57.38%and 90.00%,respectively;The nucleation temperatures of 1#,2#,and 3#base glasses are 1000℃,985℃,987℃,respectively;and the crystallization temperatures of 1#,2#,and 3#base glasses are 1076℃,1080℃,and 1072℃,respectively.