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Generation of Respirable Coal Dust                                131






















           Figure 9.4 Variation of respirable dust index with moisture.


           9.4.2  Effect of Volatile Content or Carbon Content
           The fixed carbon content (DAF) is equal to 100-volatile percentage (DAF). Both of
           these measure the degree of metamorphosis the coal has undergone. Figure 9.5
           shows a graph of RDI against volatile matter content (DAF). For the range of vol-
           atile matter content 5% to 35%, there is no great decrease in RDI. The data are
           somewhat scattered, but a decrease in RDI with increasing volatile content is
           discernible. With increase in volatile matter content beyond 35%, the RDI appears
           to fall sharply.




























           Figure 9.5 Variation of respirable dust index with volatile matter content (DAF).
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