Geochemical Characteristics And Migration Patterns Of Hazardous Elements In Coal Combustion Products Of Handan Power Plants

Coal-fired power generation is the main way of power supply in China.However,coal-fired power plants produce a large number of coal combustion products.These coal combustion products are easy to accumulate toxic and hazardous elements on the surface,which will cause harm to the environment and human body,and even pose a threat.In recent years,coal combustion by-products have attracted more and more attention because of their large output and the adverse effects of potential toxic elements on the environment.In this paper,raw coal,slag and coarse ash of power plant and indoor temperature-controlled coal ash are taken as research objects.The determination of hazardous elements in coal and coal ash samples by Inductively coupled plasma mass spectrometry(ICP-MS)was used to analyze the enrichment characteristics of hazardous elements in coal and coal ash.The occurrence state of elements is studied by step-by-step chemical extraction method,the particle morphology and mineral composition of coal and ash were determined by Scanning electron spectroscopy(SEM-EDS)and X-ray diffraction(XRD);and the distribution and occurrence of harmful elements before and after coal combustion were studied.The experimental results show that the main minerals in raw coal are quartz,kaolinite and calcite,followed by pyrite;the minerals in coal ash are relatively single,mainly mullite and quartz,while quartz,magnetite and hematite are the main minerals in temperature control ash.According to the migration behavior of elements,harmful elements can be divided into three categories: I-The elements Cr,Mn and Ni(REI>0.85)remained in solid waste(slag,coarse ash and fly ash);II-Some elements in solid waste are Be,Co,Cu,Zn,Mo,Cd,Ba,Pb,Bi and U(0.1<REI<0.85);III-Few elements are mainly volatilized into the atmosphere,such as Sb(0.1<REI).At the same time,the mechanism of element migration is discussed,which is related to particle size of coal ash,combustion temperature,occurrence state,etc.Based on the study of geochemical characteristics study of coal and coal ash,the migration patterns of hazardous elements between coal and coal ash and the migration mechanism of elements are comprehensively analyzed,which has a guiding role in the comprehensive utilization of coal and coal ash and environmental improvement.