Study On Safe Disposal Of Fly Ash From Municipal Solid Waste Incineration In Lhasa

Tibet’s natural environment is fragile and ecological restoration is difficult.As a national ecological security barrier,Tibet’s ecological environment construction is the prerequisite and foundation for development.As the growth of the Tibetan economy level and the vigorous development of tourism,Tibetan living garbage also increased year by year,to improve the level of urban living garbage reduction,recycling and harmless,Lhasa first built a waste incineration power plant,but produced during waste incineration fly ash belongs to hazardous waste,the processing of fly ash has become a common concern.Fly ash melting treatment is to heat solid waste such as fly ash to1300-1500℃,the formation of dense vitreous,reduce heavy metals and other pollutants outside migration,melting treatment technology has significant reduction,high product stability,harmless degree thorough,and can be utilized and other advantages of resources.However,fly ash melting treatment technology has high energy consumption and processing cost,so how to reduce energy consumption is a hot research topic.Additives are an effective way to change the sintering and melting behavior of fly ash,because specific additives can change the chemical composition of fly ash,thus changing the melting characteristics.Appropriate additives can not only reduce the difficulty and cost of melting process,but also inhibit the emission of other pollutants.This experiment is mainly to study the influence of particle size on the melting characteristics of fly ash and the influence of single component on the melting characteristics of Lhasa fly ash under different particle size,and the comparison between the use of chemical reagent treatment method and melting treatment technology of Lhasa fly ash.Experiment will first fly ash in Lhasa sieving is divided into four different particle size of fly ash,by XRF experiment analysis of four different particle size composition of fly ash,calculating alkalinity found four different particle size of fly ash alkalinity in Lhasa is different,the original grey basicity is 3.04,the particle size of fly ash of basicity is 2.36,large particle size of fly ash alkalinity is 3.18,The fly ash basicity of small and medium particle size is 2.88,and that of small particle size is 3.19.In addition,the small and medium particle size of Lhasa fly ash accounts for the majority,and the fly ash with particle size less than 150μm accounts for 70.4%of the weight.Through XRD analysis,it is found that the fly ash crystals with four different particle sizes mainly contain Si O₂,KCl,Na Cl and Ca SO₄.By comparing the melting characteristics of fly ash with four different particle sizes,it is found that the melting characteristic temperature of fly ash with small particle size and large particle size is lower than that of original ash.The chemical reagent treatment method is selective to the stability of heavy metals and can only stabilize some heavy metals.Although the melting technology for heavy metal leaching has good stability,but the treatment cost is high,the market penetration is low,the operation is more complex and so on.Through comparison,the experiment finally selected small and medium particle size fly ash and small particle size fly ash as the target sample,adding Ca O,Na₂O,Si O₂,Al₂O₃ four additives,the final conclusion is that whether it is small and medium particle size fly ash or small particle size fly ash,Si O₂ can significantly reduce the melting characteristic temperature of fly ash.When the fly ash with small and medium particle size is between 0.78-1.1,the lowest deformation temperature is 1203℃,and the four characteristic temperatures are all below 1230℃.When the fly ash with small particle size is between 0.69-1.05,the lowest deformation temperature is 1200℃,and the four characteristic temperatures are all below 1230℃.The melting characteristic temperature of fly ash with small particle size is lower than that of fly ash with small particle size.