Cprek Nick, Shah Naresh, Huggins Frank E, Huffman Gerald P
Consortium for Fossil Fuel Science, University of Kentucky, 533 S. Limestone Street, Lexington, Kentucky 40506-0043, USA.
Environ Sci Technol. 2007 May 15;41(10):3475-80. doi: 10.1021/es062938j.
Determination and classification of quartz in coal fly ash (CFA) is a subject of interest because of the adverse health effects caused by inhalation of crystalline silica. Workers with prolonged exposure to this carcinogen can develop respiratory diseases over time. This obviously may include utility plant workers involved in the handling, loading, and hauling of CFA. In this investigation, computer-controlled scanning electron microscopy (CCSEM) and X-ray diffraction (XRD) were used to investigate Si-rich phases in CFA to develop a better approach for the determination of respirable quartz. Three CFA samples from utility boilers and a NIST standard CFA sample were investigated. The XRD measurements indicated that the four samples contained from 7.0 to 16.0 wt.% of quartz. The CCSEM measurements utilized both particle size distributions and a particle shape parameter, circularity, to classify the Si-rich phases in these ashes as either crystalline or amorphous (glass). The results indicated that the amount of free, respirable, quartz in these CFA samples ranged from only 0.1-1.0 vol % and showed little correlation with the XRD results for the bulk ash. These results are significant in view of the factthat XRD is the traditional method of measuring crystalline silica in dust collected from workplace atmospheres.
由于吸入结晶二氧化硅会对健康产生不利影响，因此对粉煤灰（CFA）中石英的测定和分类成为一个备受关注的课题。长期接触这种致癌物的工人随着时间的推移可能会患上呼吸道疾病。这显然可能包括参与粉煤灰处理、装载和运输的公用事业工厂工人。在本研究中，使用计算机控制扫描电子显微镜（CCSEM）和X射线衍射（XRD）来研究粉煤灰中富含硅的相，以开发一种更好的可吸入石英测定方法。研究了来自公用事业锅炉的三个粉煤灰样品和一个NIST标准粉煤灰样品。XRD测量表明，这四个样品中石英含量为7.0至16.0 wt.%。CCSEM测量利用粒度分布和颗粒形状参数（圆度）将这些灰烬中富含硅的相分类为结晶相或非晶相（玻璃相）。结果表明，这些粉煤灰样品中游离的、可吸入的石英含量仅为0.1 - 1.0 vol%，与散装灰的XRD结果几乎没有相关性。鉴于XRD是测量从工作场所空气中收集的粉尘中结晶二氧化硅的传统方法，这些结果具有重要意义。
