淮南潘一矿煤基固废精细化学结构及重金属生态风险评价

Coal-based solid waste from the Panyi Mine in the Huainan mining area:Fine-scale chemical structure and ecological risk assessment of heavy metals

煤基固体废弃物的清洁利用是矿区生态建设亟待解决的问题,重金属的结构形态是煤基固废清洁利用的关键。以安徽淮南矿区潘一矿煤矸石、粉煤灰为研究对象,利用XRF、XRD、SEM和FTIR等微区方法对煤基固废进行表征分析,探讨其精细化学结构及重金属嵌布方式,并结合RAC(Risk Assessment Code)生态风险评价对重金属潜在风险进行评估。结果表明,煤矸石主要粒径以黏粒(0~5μm)和粗粉砂(10~50μm)为主,粒度不规则,空间分布间距较大,主要矿物为石英(SiO2),IR谱线辅助验证了AlO4和SiO4的弯曲振动。粉煤灰粒径以粗粉砂(10~50μm)和砂砾石(50~250μm)为主,表面以球状包裹体和多孔颗粒组成,粒径大小不一,主要矿物相是莫来石(Al6Si2O13),IR谱线发现其存在有机硅Si-O-Si对称伸缩和反对称伸缩。煤矸石中Ni、Pb以有机结合态和铁锰氧化物结合态为主,Cr、Cd、As的赋存形态主要是残渣态;粉煤灰中As主要以残渣态和有机结合态存在,其余重金属元素均以残渣态存在。RAC生态风险评价结果表明,煤矸石和粉煤灰中Cr、As属于低风险水平,其余重金属均无风险。研究结果对煤基固废资源化利用及矿区生态环境保护具有重要的现实意义。

The utilization of clean coal-based solid waste is a pressing issue in the ecological construction of mining areas.To address this issue,the key is to ascertain the structures and morphology of heavy metals in coal-based solid waste.This study investigated the coal gangue and fly ash samples from the Panyi Mine in the Huainan mining area,Anhui Province.First,this study characterized the coal-based solid waste using microanalysis methods,such as X-ray fluorescence spectrometry(XRF),X-ray diffraction(XRD),scanning electron microscopy(SEM),and Fourier transform infrared spectroscopy(FTIR).Then,it examined the fine-scale chemical structure and heavy metal dissemination modes of coal-based solid waste.Finally,this study assessed the potential ecological risks of heavy metals by combining the risk assessment code(RAC).The key findings are as follows:(1)The coal gangue,dominated by clay particles(0-5μm)and coarse-grained silts(10-50μm),exhibits irregular particle sizes and large spatial distribution spacings.Its main mineral is quartz(SiO2),with the bending vibrations of AlO4 and SiO4 presence in its infrared(IR)spectra.In contrast,the fly ash,dominated by coarse-grained silts(10-50μm)and sandy gravels(50-250μm),manifests spherical inclusions and porous particles on the surface,varying in particle size.Its main mineral is mullite(Al6Si2O13),with symmetric and anti-symmetric stretching vibrations of Si-O-Si within organosilicon present in its IR spectra.(2)In the coal gangue,Ni and Pb are primarily organic bound or bound to Fe-Mn oxides,while Cr,Cd,and As predominantly occur in the residual form.In the fly ash,As principally occurs in residual and organic bound forms,while other heavy metals occur in the re-sidual form.(3)As indicated by the RAC-based ecological risk assessment,Cr and As in both coal gangue and fly ash are at a low risk level,and other heavy metals in them do not pose a risk.The results of this study hold practical signific-ance for the reutilization of coal-based solid waste and the eco-environmental protection of mining areas.