Study On The Transformation Behavior Of Arsenic In The Process Of Washing Coal Combustion

Arsenic is one of the most harmful trace elements in coal, in the process of coal combustion, the volatilization of arsenic gives great harm to the ecological environment and human health, therefore, the transformation of arsenic in coal has become a research focus in the international scholars. In this article, raw coal, washing products and washing by-product were selected,which are from jiaozuo coal preparation plant A and coal preparation plant B,as the research object.Using atomic fluorescence spectrometer to determine the arsenic content in the sample, the enrichment characteristics and the concentration rate of arsenic in samples were explored. Through the comparison of sequential chemical extraction experiments,and with the analysis of X-ray diffractometer in raw coal and coal slime,the best sequential chemical extraction experiment plan was used; In the muffle furnace combustion experiment, the arsenic volatilizing rate of different samples at different temperatures could be discussed, and based on this,the migration and transformation of arsenic in the combustion process is studied.Based on the study,the major results of this research are shown as belowing:(1)The arsenic content of Jiaozuo coal is in the range of 9.03 to 13.92 ug/g,which is higher than the henan region(5.19 ug/g) and China(3.18 ug/g), but lower than the content of arsenic in the USA(24 ug/g).(2) The arsenic content of cleaned coal in jiaozuo coal preparation plant A and B has been decreased.The removal rate in the range of 24.26% to 73.19%. To the washing by-products, arsenic content in the coal gangue is the highest, up to 42 ug/g.The arsenic in coal slime is relative to Enrichment.the enrichment rate of coal preparation plant B was the highest, so to the use of coal slurry, we need to pay attention to the harm of arsenic on the environment.(3) The content of arsenic(0.71 to 1.28 mg/L) in wash water before and after washing water of the two coal preparation plant is overed the state emission standard.(4) The mineral compositions in raw coal and coal slurry is slightly different.Raw coal has kaolinite content in the highest(52.50%), and quartz(28.7%),and calcite, anatase,metal material. Coal slurry containing calcite, quartz and kaolinite(43%),whose quartz content is the highest(48%).(5) To theall samples, the content of water soluble and exchangeable states is the lowest, in the range of 0-4.66%; Residue content is the highest(42.87% 69.64%), in addition to the youzhong and xixiaokuai.The organic state content in the youzhong and xixiaokuai is highest, up to 40.23% and 59.11% respectively.(6) In the muffle furnace combustion experimental research, the concentration of arsenic in coal base of each sample are all declined,along with the increase of temperature.(7) Under the different burning temperature, mineral chemical reactions is also different, therefore, the changing trends of arsenic volatilizing rate of sample is different also.