城市生活垃圾焚烧灰渣熔融特性的分析

分析了城市生活垃圾焚烧灰渣熔融过程中CaO、SiO2、Al2O3等主要成分以及实验气氛对熔融特性的影响,并分析了熔渣的物理化学性能.实验结果表明,灰渣中CaO含量的高低决定了灰渣的酸碱度和灰渣的熔点.当CaO的质量分数占灰渣总量的33%左右,灰渣的熔融温度最低;而灰渣中总碱性氧化物的质量分数低于48%时,生活垃圾焚烧灰渣熔点随碱性氧化物质量分数的增加而降低;而当碱性氧化物质量分数大于48%时,碱性氧化物对生活垃圾焚烧灰渣熔点的影响则相反.以SiO2、Al2O3等氧化物为代表的酸性氧化物,其含量在生活垃圾焚烧灰渣中已经饱和,硅铝氧化物的添加,则会升高灰渣的熔点.为了降低灰渣的熔点,应将灰渣的酸碱度控制在1左右,并在弱还原性的气氛下进行熔融处理.熔融处理后的熔渣因具有性能稳定,重金属浸出量低,几乎不含有二噁英类毒性有机物,完全可以直接成为可利用再生资源.

Analysis on the melting features of municipal solid waste incineration residues

The present paper is aimed at reporting the authors' analysis on the melting features of municipal solid waste incineration residues and their control and disposal, including that of the bottom ash, fly dusts and air pollutants with thick content of heavy metals, salts as well as organic pollutants. In addition to the physical and chemical features of the molten slag, the paper has also analyzed the content of CaO, SiO_2,Al_2O_3 and the experimental condition influence, as well as the features of some solid waste fusion residues. The results of our analysis show that it is the content of CaO that determines the acid-alkalinity and melting point of solid residues. When the content of CaO is about 33% in the residues, the melting point of residues would be lowest. However, the alkaline oxides also affect their melting point. But, when the content of alkaline oxides is below 48%, the melting point would be getting lower and lower with the increase of the alkaline oxide gross. On the contrary, if the alkaline oxide content is higher than 48%, the tendency would be getting reversed. The melting point would be getting higher and higher while acidity oxides are added to the residues, for the content of acidity oxides would be getting saturated. It would be better to control the acid-alkalinity at about 1 degree so as to reduce the melting point of residues and keep the mild deoxidization with the proper atmosphere of melting kiln. However, the melt slag would appear stable and steady with no dioxins content in. And, in turn, there will be little leaching content of heavy metals in the slag, which can be directly turned from the melting of urban solid waste into some reusable resources.