The manufacture of metal products involves a wide variety of processes: foundry operations, metal cutting, forming, polishing, grinding, welding, painting, and more. All these steps generate dust and oil mists, sometimes in significant quantities. For example, producing one tonne of steel from scrap melted in an electric steelworks releases 20 kg of dust containing zinc, iron, and heavy metals. What risks does this pose for operators and machinery? What industrial dust-collection solutions should be implemented?
Dust hazardous to humans and the industrial environment
Employee exposure to metal compounds, in the form of fumes or dust, can lead to acute or chronic respiratory diseases and, in some cases, neurological and cardiovascular disorders. This occupational exposure to various metal compounds is also a risk factor for cancer. It is therefore regulated by strict standards.
Fumes generated, for example, during the welding process can penetrate deep into the lungs, where they may cause severe damage and spread into the bloodstream. Exposure to welding fumes can also lead to numerous pulmonary, renal, and central nervous system diseases. In France, the occupational exposure limit (OEL) over eight hours for the total particulate content of welding fumes is 5 mg/m³. Individual occupational exposure limits for each component of the fumes must also be respected.
These dusts also pose problems from an industrial perspective. Grinding, for example, produces abrasive dust with agglomerating properties, consisting of coating materials, metallic particles, abrasive wheel fragments, and wheel bonding agents. These particles threaten the integrity of the machinery and the quality of the manufactured products, and often present a risk of fire and explosion. Dust and fumes generated by metalworking processes must therefore be collected either from the ambient air or directly at the source, depending on the installation.
Dust and fumes
Because of the high temperatures reached at the melting point, all welding processes emit potentially harmful fumes that can be inhaled by welders and nearby personnel. Mixed with hot air, these fumes may contain gases and dust. Given their small size and, depending on their composition and concentration, these particles may present a health risk for operators. The main pollutants found in these fumes include: chromium VI, nickel, formaldehyde, cobalt, aluminum, lead, titanium, and carbon monoxide.
Cutting and punching operations can also generate dust. In foundries, operators are likewise exposed to dust-laden environments (sanding, shearing). Grinding wheels or polishing felts made from cotton, cloth, chamois, or string generate various contaminants originating either from the wheel itself or from the processed material, such as long fibrous strands, cotton agglomerates, or fibers mixed with waxes, oil, or abrasives.
Find an example of a solution for filtering shot-blasting dust.
Oil mists
Oil mists are particularly common in the metallurgical sector. These aerosols are generated when oil is used for cooling or lubrication during the machining of metal parts. Oil vapor forms upon contact with the hot machined surface, evaporates, then condenses into microscopic particles. These mists settle as a greasy film that can make surfaces slippery, accumulate on machinery, walls, and ceilings, and damage sensitive components such as electronic parts. They also present significant health risks. For example, exposure to oil mists is associated with an increased risk of bladder cancer. Eliminating oil mist is therefore essential to ensure workplace safety and cleanliness.
Expert advice
Bag filters are often installed in air-handling units (AHUs) used to treat high oil loads in the air.
Discover two examples of filter systems used for oil mists:
Example of bag-filter installation for AHUs in the automotive industry
Focus: aerosols, dust, mists, or fumes?
The generic term aerosol refers to extremely fine particles found in the air, such as solid or liquid particles, dust, fumes, and mists. Dust consists of extremely fine solid particles generated, for example, by mechanical processes and present in the air. Mist is composed of small droplets of liquid (water, oil, etc.) suspended in the air. Finally, fumes are the gaseous residues of combustion. Often, very fine solid materials such as soot or metallic oxide particles can mix with the gases that make up the fumes.
Contact a filtration expert
We are at your service
Our experts place their knowledge and expertise at your disposal for liquid filtration, air and gas filtration, decontamination, and separation technologies.
