Surface mining and crushing, conveying and processing of mined material produce high volumes of heavy, abrasive and possibly toxic dust. Dust is a problem at every point in the mineral excavation and processing chain, from initial excavation to transport, conveying, crushing, grinding and storing of minerals and mineral ores. If this dust is not controlled, companies may face sanctions by OSHA, the EPA and the Mine Safety and Health Administration (MSHA). RoboVent provides dust control solutions for quarries, open-pit mines, ore silos and all stages of the mineral processing industry.
Solutions for Mining and Mineral Processing
Dust Control Applications for Mining and Mineral Processing
Dust Control Challenges for Mining and Mineral Processing
Health Risks of Mining and Mineral Processing Dust
Regulations for Mining and Mineral Processing
Considerations in Dust Control for Mining and Mineral Processing
Mining and Mineral Processing Solutions
The mining industry includes not only excavation sites (e.g., surface mining, open-pit mining, quarrying, mega-mining, open-cast mining and open-cut mining) but also all of the infrastructure for processing mined materials and ores and turning them into usable raw materials.
Mined materials include sand and gravel, stone, coal, metals (e.g., iron, lead, copper, gold, silver, platinum, aluminum, zinc, lithium, nickel, molybdenum, manganese, cadmium, beryllium, chromium, tin, tungsten), nonmetals (e.g., phosphate, gypsum, talc, feldspar, pumice and gemstones) and rare-earth minerals (e.g., neodymium, dysprosium, yttrium, europium, terbium). In North America, the most common mine types by far are sand, gravel and stone, followed by coal. Copper and iron are the most common metal mines.
Heavy, abrasive dust is produced at a number of points in the mining industry. These include:
Dust control for mining and mineral processing has a number of challenges due to the volume, abrasiveness and toxicity of mining dust. While the specific challenges vary by mineral or ore type and process, there are some general challenges common to all mining applications.
Mining and mineral or ore processing produce heavy, abrasive dust that is irritating to the eyes, skin and tissues of the nose, throat and lungs. Dust produced by mining operations may be heavy enough to create visibility challenges or slip-and-fall hazards. Mining dust may also contain elements that are toxic when inhaled.
Fine dust produced when crushing, grinding and transporting minerals and ores can be inhaled deeply into the lungs, where it becomes embedded in lung tissue. Lung cancer, pneumoconiosis, asthma, chronic obstructive pulmonary disease (COPD), silicosis and progressive massive fibrosis (PMF) are all associated with exposure to mineral dusts from mining and ore processing. Exposure to heavy metals and other toxic elements in mining dust can lead to a variety of pulmonary, nervous system and developmental and reproductive effects.
The toxicity of mining dust will depend on its exact composition. However, companies in the mining industry should be aware that exposures are not limited to the target mineral or metal; ores and extracted minerals are typically commingled with rock, soil and other non-target elements. A dust analysis can determine the exact composition of dust created at a specific extraction site. These are some of the most common hazards with mining and mineral processing dust.
The mining industry is highly regulated. In the U.S., companies involved in mineral extraction and processing must follow regulations related to dust control from multiple industries, including the Occupational Safety and Health Administration (OSHA), the Environmental Protection Agency (EPA) and the Mine Safety and Health Administration (MSHA)
Permissible Exposure Limits for Mining and Mineral Processing Dust
OSHA has issued specific regulations for many different metallic and nonmetallic dusts found in mining applications. These are expressed as Permissible Exposure Limits (PELs), which are measured and averaged over a worker’s 8-hour shift.
Companies involved with mineral extraction and processing must first consider the general limit for exposure to particulate of any kind (i.e., nuisance dust, PM10 dust). The limit for “Particulates Not Otherwise Regulated” (PNOLs) is 15 mg/m3 (8-hour TWA limit) for total particulate and 5 mg/m3 for respirable particulate. Employers must also follow general housekeeping standards (OSHA 1910.22, Walking-Working Surfaces) to prevent accumulation of dust on surfaces.
Manufacturers are responsible for ensuring that workers are not exposed to hazardous dusts in levels above the PELs. Failure to control dust in areas where workers may be exposed can result in serious fines and legal action. For some highly toxic substances, such as lead and crystalline silica, OSHA also sets a separate action limit; exposures above this limit may require specific compliance activities such as blood testing. These are PELs for some of the metals and other elements found in surface mining, quarrying and mineral ore processing.
In general, companies are expected to use engineering controls to reduce exposure levels to within the PELs wherever possible. Personal protection equipment (PPE) should only be relied on in situations where it is not technically possible to meet the PEL through engineering controls.
Companies in the mining industry must meet certain environmental standards, which may include:
While particles of sand and large dust are not currently regulated, the EPA regulates inhalable (PM 10/10 μm and smaller) and fine respirable (PM 2.5/2.5 μm and smaller) particulate. The EPA sets clean air standards for inhalable and fine respirable particulate that state and local governments are required to enforce. Large particulate producers, including mining companies and mineral processors, are subject to state and local limits on particulate emissions to keep local air quality within EPA regulations.
In general, companies involved in mineral extraction and processing cannot simply allow dust and emissions to go into the atmosphere. That means that companies must have a dust control system in place to collect excess dust for proper disposal.
Combustible Dust Regulations
Some dust types produced by the mining industry are combustible, most notably coal dust. Combustible dusts are regulated under OSHA’s General Duty Clause (Section 5(a)(1)) with additional requirements under the Hazardous Locations (§1910.307), Hazard Communication (§1910.1200) and Housekeeping (§1910.22) standards. OSHA’s Combustible Dust National Emphasis Program (NEP) outlines policies and procedures for inspecting workplaces that create or handle combustible dusts.
In addition, manufacturers dealing with combustible dusts must follow National Fire Protection Association (NFPA) standards for prevention of fires and explosions. Mining dust from metal and nonmetal mining and mineral processing falls under NFPA 122, Standard for Fire Prevention and Control in Metal/Nonmetal Mining and Metal Mineral Processing Facilities. Material handlers in the mining industry may also need to follow NFPA 654, Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing and Handling of Combustible Particulate Solids.
Sand, silica, limestone and gravel dust are generally inert and do not require special combustion precautions. However, these dusts should be tested to determine whether there are other combustible dusts commingled with the rock dust.
Because of the diversity of dust types and processes represented across the mining and mineral processing industry, there is no “one size fits all” solution for dust control in mining. The National Institute of Occupational Health and Safety (NIOSH) has created the Dust Control Handbook for Industrial Minerals and Mining as an overview of basic principles. Companies should also follow ACGIH general guidelines for industrial ventilation and filtration when designing a dust control solution.
The specifics of the mining dust collection solution will depend on the process, the type and volume of dust produced, and the environment in which the dust is produced. Modifications are likely to be needed to accommodate environmental conditions, the volume and abrasiveness of the dust, and combustion risks.
Because the dust collection system will be outdoors for many mining applications, the dust collector cabinet and ductwork must be built to withstand the elements. Look for:
Abrasive Dust Control
The abrasive nature of mining and mineral processing dusts, along with high overall volumes of dust, creates special challenges for the design of the dust collection system. Dust collectors for mining dust are likely to require modifications to protect the filters and extend the life of the dust collector. These modifications may include:
Combustible Dust Control
Depending on the volume and combustibility of the dust, the dust collector may need to be equipped with a deflagration system. This system may include:
Storage of combustible mining dust will require a bin venting dust collector. The dust collector is mounted directly to the top of the bin, hopper or silo to collect airborne particulate within the enclosure. If the dust is combustible, both the bin vent dust collector and the storage unit should have explosion relief panels.
Filter Considerations for Mining and Mineral Processing Dust
Mining and mineral processing require high-quality, heavy-duty filter media.
Industrial dust collectors used in mining and mineral production should have features to help reduce maintenance and enable dust collection and disposal without shutting down the unit.
The dust collection system will require customization for the volume of dust collected during mining. A conveyor system may be used to collect large volumes of dust and convey it to large storage containers for proper disposal.
Senturion is the most flexible and versatile industrial dust collector on the market today.
Activated by smoke or heat, the Supprex-200 acts quickly to suppress a fire. Airflow is shut off, and, if needed, FM-200 gas is deployed. Cleanup is minimal.
An advanced particulate-monitoring device capable of detecting leaks past the filters. If one should occur, SafeSensor shuts the system down and triggers an alarm.