Coal And Coal Combustion Study Of The Distribution Of The Trace Elements Arsenic, Bromine, Iodine,

The trace elements emitted during the coal combustion will greatly damage the mankind and the environment, which are receiving increased attention throughout the world. Little information about the determination and distribution of trace elements during the process of coal combustion was reported because the amount of the trace elements is small and they are difficult to be measured. This paper regarded the typical volatile trace elements arsenic (As),bromine(Br) and iodine(I) as the targets, a method was established for simultaneous determination of trace elements, such as, arsenic (As), bromine (Br) and iodine (I) in coal and coke. Some researches on distribution and controlling of volatilization of trace elements through simulating the actual coal combustion had been done in this thesis.(1) Using high pressure and closed microwave digestion technology, the imports and exports of coal and coke samples from different countries were digested quickly with mixed acids of nitric acid, hydrofluoric acid, and hydrogen peroxide solution, with the help of Inductively Coupled Plasma Mass Spectrometer (ICP-MS), a method was established for simultaneous determination of trace elements, such as, arsenic (As), bromine (Br) and iodine (I) in coal and coke. The influence of the medium of nitric acid and other acids on the determined elements was researched. The unstable mass signal of bromine and iodine on account of different valencies could be made stable by adding sodium persulfate. And the silver ion could catalyze and accelerate the reaction mentioned earlier. High memory effect of halogen was effectively decreased by a washing step with neutral mixed lotion. The low detection limits were in the range of 0.1–5.0 ng/L with relative standard deviations of 1.5%–12.0%, and the recoveries were in the range of 80%–106.7%.The analysis results were satisfactory.(2) The best absorption liquor was chosen through simulation amount of coal combustion. The unstable mass signal of indium could be made stable by adding EDTA. Different affection of conditions such as time,gas flux,temperature on volatilization of trace elements arsenic (As), bromine (Br) and iodine (I) were studied.The gas,ash and residue brought from coal burning were also analysed using high pressure and closed microwave digestion technology and Inductively Coupled Plasma Mass Spectrometer (ICP-MS), the distribution of trace elements arsenic (As), bromine (Br) and iodine (I) were discussed, showing that the result of the method of coal buring were consistent with the method of microwave digestion Inductively Coupled Plasma Mass Spectrometer (ICP-MS).We also researched the affection of the additive sodium carbonate etc on the controling of trace elements arsenic (As), bromine (Br) and iodine (I).