Reducing Enclosed Cab Drill Operator's Respirable Dust Exposure with Effective Filtration and Pressurization Techniques

Abstract

Many different types of surface mining equipment use enclosed cabs to protect equipment operators from health and safety hazards. The overburden removal and mining process can be extremely dusty and can cause excessive dust exposure. To study this issue, a cooperative research effort was established between the National Institute for Occupational Safety and Health, U.S. Silica Co., Clean Air Filter Co., and Red Dot Corp. in an effort to lower respirable dust levels in an enclosed cab on an older surface drill at a silica sand operation. Throughout this research effort, a number of modifications were incorporated into the drill's filtration and pressurization system, as well as in other areas, to improve its design and performance. An average cab efficiency of 93.4% was determined with gravimetric sampling instruments when comparing the outside with the inside cab dust levels on the final design. Although this study considered just one operation, the goal was to identify cost-effective improvements that could be implemented on all types of enclosed cabs to lower respirable dust concentrations. Two critical components for an effective enclosed cab system are having a properly designed, installed, and maintained filtration and pressurization system, along with a method for maintaining structural cab integrity, which allows the cab to be positively pressurized. Another important component is maintaining cab cleanliness. Although this research was originally directed toward the mining industry, it is also applicable to agricultural or construction equipment.

Metal and non‐metal miners' exposure to crystalline silica, 1998–2002

“…Feasible and effective engineering controls for dust in mining operations are available [Burgess et al, 1989;Kissell, 2003]. Dust controls for surface drilling operations are effective [Cecala et al, 2005;Weeks, 2002] and have been mandatory since 1994 (30 CFR 58.620). Dust controls for bag-filling, one of the jobs with historically high exposure levels, have been well known since at least 1964 and bagging machines currently available have local exhaust ventilation hoods as an integral part [Burgess, 1995].…”

Instituting a filtration/pressurization system to reduce dust concentrations in a control room at a mineral processing plant

“…Early on in this research effort, numerous in-cab dust sources were identified that increased the equipment operator’s respirable exposure, including dust-laden work clothing, work boots, control panels, and dust on the cab’s inside walls (Cecala et al, 2001, 2004, 2005 and 2007). A comprehensive laboratory study was performed to evaluate the various factors and parameters that are critical for an effective filtration and pressurization system in an enclosed cab (Organiscak and Cecala, 2009a, 2009b; Organiscak et al, 2008).…”

Best practices for dust control in coal mining.

“…Filter efficiency performance specifications used in the field were 95% or greater on respirable-sized dusts [Chekan and Colinet 2003;Cecala et al , 2005Organiscak et al 2003a]. Laboratory experiments showed an order of magnitude increase in cab protection factors when using a 99% efficient filter versus a 38% efficient filter on respirable-sized particles [NIOSH 2007].…”