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KMID : 0895419970070020196
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Journal of Korean Society of Occupational and Enviromental Hygiene
1997 Volume.7 No. 2 p.196 ~ p.208
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Analysis of Quartz Content and Particle Size Distribution of Airborne Dust from Selected Foundry Operations
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김용우/Kim, Yong Woo
김현욱/이광묵/노영만/피영규/김형아/원정일/Kim, Hyun Wook/Lee, Kwang Mook/Roh, Young Man/Phee, Young Gyu/Kim, Hyoung Ah/Won, Jeoung Il
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Abstract
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This study was performed to estimate quartz contents in the both bulk and airborne dust samples and to determine particle size distribution of airborne dust from the selected foundry operations. Total dust samples were collected by a 37㎜ cassette and respirable by a 10 ㎜ nylon cyclone. Particle size distributions were determined by a Marple´s 8-stage cascade impactor at the melting, molding, shakeout and finishing operations. The presence of elements in the dust samples were confirmed by the scanning electron microscopy equipped with the energy dispersive x-ray spectrometry. The quartz contents were estimated using the intensity of the absorption peak of quartz at 799 cm-1 by the Fourie Transformed Infrared Spectroscopy (FTIR).
The results were as follows:
1. The analysis of data from cascade impactor showed bimodal distributions of particle size at the melting, molding and shakeout operations. Mass median aerodynamic diameters for the distributions determined by histogram were 0.48-1.65 ㎛ for small and 13.43-19.8 ㎛ for large modes. In the dust samples collected at the finishing operations, however, only a large mode of 18.89 ㎛ was found.
2. The percentages of total to respirable dust concentration calculated from the impactor data ranged from 42 % to 66 %. The average concentrations of respirable dust by cyclone were 0.85-1.28 ㎎/㎥ collected from the workers, and were 0.23-0.56 ㎎/㎥ from the areas surveyed. Dust concentrations of personal samples were statistically significantly higher than those of area samples. The highest dust concentration was obtained from the personal samples af the finishing operation.
3. The mean percentages of silicon and oxygen estimated by SEM-EDXA in the bulk samples ranged from 35.83 % to 36.02 %. and from 39.93 %-41.64 %, respectively.
4. The average quartz contents estimated by FTIR in the respirable dust from personal samples ranged from 4.32 %. to 5.36 % and 4.54 % to 4.70 % in the bulk samples. No statistical difference of quartz content was found between foundry operations.
In this study, quartz content was quantified by FTIR. Although no statistically significant difference in quartz content between airborne and bulb: samples and between different foundry operations was found, it is recommended that quartz content in the individual sample of respirable dust he analyzed and the results he used either to select an applicable quartz limits or to calculate the exposure limit.
Further studies, however, are needed to compare the results by FTIR and XRD since it is reported that the quartz content determined by FTIR is different from that by XRD.
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