Martin Engineering has developed practical solutions to comply with the U.S. Mining Safety and Health Administration’s (MSHA) new dust emissions rule. These solutions aim to control conveyor dust at its source, which has global implications as similar policies often follow in other countries. For years, the company’s engineers have focused on reducing conveyor-borne dust through various accessories and engineered systems that enhance workplace safety and efficiency. These solutions are field-tested and have delivered measurable results in mines and bulk handling operations worldwide.
The MSHA rule limits dust exposure to a personal exposure level (PEL) of 50 μg/m³ over an 8-hour shift, with an action level of 25 μg/m³. It applies particularly to miners diagnosed with or showing early signs of pneumoconiosis (black lung). Operators are required to install or repair equipment that uses engineering controls to limit dust at its source. Administrative controls and temporary personal protective equipment (PPE) may also be used, though PPE is not considered a long-term solution.
A significant amount of conveyor belt dust is generated at loading and discharge zones. Passive dust reduction methods, which don’t require machinery or electricity, are particularly effective in these areas. Fully enclosing transfers, using dust curtains and bags, minimizes airflow and captures dust. Shorter or sloped loading chutes also help reduce dust by limiting the impact of cargo on the belt. Proper belt training ensures centered loading, reducing spillage and dust, while preventing belt sag between idlers helps seal gaps where dust can escape. Impact cradles, equipped with shock-absorbent polyurethane bars, maintain a smooth belt plane and reduce strain, further minimizing dust.
Lower belt speeds, typically around 2 m/s (394 fpm), are effective in reducing dust but present a tradeoff with the need for wider belts to handle the same material volume. Proper belt tension and idler spacing are also critical to controlling dust, as they reduce material splash and trampling. Keeping belt sag to around 1% between idlers is a common recommendation, while idler spacing should be as close as possible, particularly in the loading zone.
Enclosing conveyor systems is another essential step in dust control. Restricting the airflow through transfer points, using dual skirting, and dust curtains helps keep dust within the material stream. Capturing material shortly after discharge and keeping the stream coalesced reduces the potential for airborne dust.
Conveyor systems have often been drafted rather than properly designed, leading to unnecessary dust emissions. Design tools and material flow modeling can improve transfer point design to minimize dust. Additionally, how conveyors are operated and maintained plays a key role in dust control. Conducting feasibility studies that focus on dust generation can improve air quality and workplace safety while enhancing operational efficiency.
