Mining Publication: NIOSH Hazard ID 1 - Exposure to Silica Dust on Continuous Mining Operations Using Flooded-Bed Scrubbers
A study was conducted examining the risk of silica (7631869) dust exposure in mine workers exposed to continuous miners equipped with flooded bed scrubbers. Recent reductions in the density of the filter media in scrubber filter panels have suggested concomitant decreases in dust collection efficiencies and increases in the exposure levels of mine workers to respirable silica dust. A description of the structure and operation of continuous miners with flooded bed scrubbers was presented. The respirable silica collection efficiencies of wire mesh filter panels constructed using 10, 15, 20, or 30 layers of stainless steel wire mesh and of two synthetic filters were examined using both high and low capacity scrubbers with supplying air velocities of 2,200 or 3,500 feet per minute at the scrubber filter. The respective collection efficiencies of the 10 and 20 layer filters at the two air velocities were 58% and 76%, and 69% and 84%. The highest collection efficiencies were measured using the 30 layer wire filter and the two synthetic filter panels composed of nonwoven synthetic fiber and an array of nylon brushes. The relative overall performance of each type of scrubber was determined using data on the silica collection efficiency and the air moving capacity of each filter panel. The 30 layer wire mesh panel and the synthetic filters were the most effective in removing silica dust. Based on these findings, the 30 layer stainless steel wire mesh and the synthetic filter panels were recommended by NIOSH for use in flooded bed scrubbers to improve silica collection.