Page 41 - HUB-4 Magazine Issue 85

Quarrying News
Origin Story: The Sources and
Remedies for Conveyor Dust Daniel Marshall, Process Engineer, Martin Engineering
The hero of this origin story is the operator who prevents dust. Particulate emissions in workplaces around the world are coming into acute focus, affecting the health and morale of workers, inspiring stakeholders to seek solutions. Long-term exposure leading chronic lung diseases is well-known, but medical studies have linked dust in bulk handling to kidney disease, heart disease, cancer, and even cognitive and memory issues. Many of these regulated particulates, such as respirable crystalline silica (RCS), are invisible to the naked eye, so staff working around a conveyor system are often unaware of the danger or the level of exposure.
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Dust control for operations with several conveyor transfers can be a serious challenge.
Operators can protect staff by understanding how particulates become airborne at each stage of the conveying process so that they can better assess the sources of dust within the system and ways to mitigate those emissions. Some dust solutions are more complicated to solve than others. Modern conveyor equipment designs have taken dust into account and offered solutions that are easier to maintain and support workplace safety compliance.
Specs on Dust Specks
In the United States, inspectors from the Occupational Safety and Health Administration (OSHA) and the Mining Safety and Health Administration (MSHA) equip trained workers with personal dust monitors that they wear throughout their shift. The small machines collect particulates from the air to measure RCS, heavy metals and other regulated substances. The filters capture particulate matter (PM) smaller than 10 microns (μm) in size. In the case of RCS, the regulated measurement must be less than 50 micrograms (μg) in weight over an 8-hour time-weighted average (TWA), i.e., a single shift.
For perspective, PM smaller than 200μm, roughly the size of sand dust, is light enough to remain airborne on ambient air currents. When PM reaches 100μm – approximately the size of a cross section of a human hair – it becomes invisible to the naked eye. At 10μm or smaller, the particulate is considered “respirable” meaning it can surpass the body’s natural defenses and enter deep into the lung causing serious damage and health issues.
Copyright © Martin Engineering 2024
Respirable dust is invisible to the naked eye, travels
long distances, and is the most detrimental to worker health.
Once measured, inspectors usually order violators to address air quality. Personal protective equipment (PPE) such as respirators can be the answer in the short term, but for the long term, regulators recommend that operators address the problem using “engineering controls.” These are equipment solutions that prevent emissions, reducing or eliminating the need for PPE. The reason for this is PPE can be hard to monitor throughout a shift, is often inadequately maintained, and the internal safety policy commonly lapses as time goes on since respirators can be challenging to wear day in and day out throughout entire shifts.
Relevant International standards include:
• Australia-AS2895-2004WorkplaceAtmospheres–Method for Sampling and Gravimetric Determination of Respirable Dust and AS3640 – 1989 Workplace atmospheres – Method for sampling and gravimetric determination of inhalable dust.
• Canada-Alberta’sOccupationalHealthandSafetyCode (2009) Part 36 (Mining) Section 601 (1)(2), 742 (1-5); Section 743 (1.1). Health, Safety and Reclamation Code for Mines in British Columbia (6.24.2); Province of Quebec’s Regulation respecting occupational health and safety in mines (98).
• EuropeanUnion-DINEN620Continuoushandling equipment and systems – Safety and EMC requirements for fixed belt conveyors for bulk materials (5.5); EN 1127- 1:1997; DIN EN 620 Annex A
• SouthAfrica-SANS1929(2011)Ambientairquality– Limits for common pollutant; National Environmental Management: Air Quality Act, 2004 National Dust Control Regulations (4.2)(6.2 a-f)
• UnitedStates–OSHA29CFR1910.22;CFR291910.307 Hazardous (classified) locations; CFR 29 1910.1200 Hazard communication; CFR 29 1910.269 Electric power generation, transmission and Distribution; CFR 29 1910.272 Grain handling facilities. MSHA 30 CFR Section 56.5001 and 57.5001
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