Research On The Distribution Of As In Coal-fired Product And The Precipitation Regularity Of As During Coal Combustion

China is a big country of coal production and consumption. There are a variety ofharmful trace elements in coal, which will present various state into environment withthe coal combustion, and cause great harm to human health and ecosystem. The peopleonly know a little about the trace elements in coal discharge regularity and controlmechanism. So the paper takes a mine field in Inner Mongolia as the object of study,makes a detail research on contents and chemical speciation of As in the product of coalcombustion and the migration and transformation of As in the coal combustion process.The results show that, the content of As in the fly ash is much bigger than its in ash.Through the analysis of the experimental results of XRD and sequential chemicalextraction, it can be draw that in the fly ash and slag, As is mainly with the Calciumbound and Oxide bound and As in the fly ash is easier than it in the ash extracted.Exchangeable and Carbonate forms of As is easier migration can readily leaching thanthe residual state, water soluble of As is the most easy to migrate, whose content is theleast. The simplified coal combustion experiments show that As easy to be enriched inthe fly ash and fine particles.By means of chemical thermodynamics software like CHEMKIN, it can be foundthat in the coal combustion process Oxygen element is the main oxidant, As existsmainly in oxidized form, a simple substance appears only in the reductive atmospherewithin a temperature range of700-800K.When the temperature is gradually reducedfrom2000K, the oxidized form of As gradually transformed into the solid phase, whichis good for catching and removing As from the flue gas. In short, As can be control asthe following methods: coal-washing technique、power coal steam blending technology、the additive of solid arsenical and ESP.