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| Open structure plant sampled for project |
Background
Workers at mineral processing facilities are often exposed to high levels of hazardous respirable dust, generally in the form of silica dust. Federal compliance records have shown that workers at these facilities have some of the higher silica exposure rates in the entire metal/nonmetal mining industry, especially in those operations processing silica sand. Many different types of structures and materials have been used to build mineral processing facilities over the past few decades. Although the structure type and building material have not historically been considered factors with respect to silica exposure, recent NIOSH studies have addressed this issue. NIOSH researchers conducted field surveys to evaluate respirable dust levels associated with three different types of processing plants: closed metal structure, closed block structure, and an open structure design. This research determined that an open structure design for mineral processing operations was superior to walled structures in terms of reducing silica exposures. Preliminary findings show that for similar production rates, the open structure is far superior because it eliminates the dust gradients that form throughout a closed structure during the course of a shift. In the open structure design, the natural environment acts as an effective method of diluting and carrying away dust generated and liberated during product processing.
Potential Outcome
It appears that the use of open structure designs shows great promise in reducing silica exposure of workers in mineral processing operations. NIOSH is discussing work with the Industrial Minerals Association-North America to further evaluate the impact of structural design on dust exposures in mineral processing operations. While the preliminary work is completed, future work would likely run through 2007, with final results available in 2008.