How to Control Dust from Conveyor Belt Transfer Points?

Why Transfer Points Generate the Most Dust

Transfer points —?where material moves from one conveyor to another —?generate far more airborne dust than the conveyor itself. The impact of falling material breaks down agglomerates and creates fine particles, while the induced air flow from material falling in the chute carries these particles out into the atmosphere. A well-designed chute can reduce dust generation by 70—?0% compared to an uncontrolled transfer point.

Dust Generation Mechanisms at Transfer Points

• Impact breakage: Material hitting the belt or chute walls at high velocity breaks into finer particles
• Induced air flow: Falling material pushes air downward through the chute; this air exits sideways carrying fine dust particles
• Skirting gaps: Air escaping through gaps between skirting and belt carries dust with it
• Carryback dust: Material sticking to belt underside dries and generates dust as it falls off on the return run

Solution 1: Chute Enclosure (Most Effective)

Enclosing the transfer chute with a sealed hood that extends from the tail of the upstream conveyor to at least 3m onto the downstream belt captures the induced air flow and contains dust within the enclosure. The enclosed air, laden with dust, is then extracted to a dust collector.

Key design requirements:

• Air extraction rate: minimum 0.5—?.5 m³/s per metre of belt width
• Enclosure must have flexible sealing at belt edges
• Access doors for maintenance with dust seals
• Dust collector: baghouse or wet scrubber, sized for extraction volume

Solution 2: Water Spray Suppression

Water spray systems wet the material surface, causing fine particles to agglomerate and fall out of suspension. Minimum application rate: 0.3—?.5 litres per tonne of material. For very dusty materials (dry fine coal, fine mineral ore): 0.5—?.0 L/t.

Spray nozzle placement for maximum effectiveness:

• Above the material stream in the chute —?not at the belt surface
• Fine mist nozzles (50—?00 micron droplet size) contact more dust particles than coarse sprays
• Avoid over-wetting —?excessive moisture causes material handling problems downstream

Solution 3: Foam Suppression

For hydrophobic materials (coal, certain minerals) that repel water, foam suppression achieves better dust capture than water alone. Surfactants in the foam solution reduce the surface tension of water droplets, improving contact with hydrophobic dust particles. Foam application rate: 0.05—?.15 L/t —?significantly less water than spray systems.

Solution 4: Belt Scraper Maintenance

Material carried back on the belt underside (carryback) is a major source of diffuse dust generation along the return run. Effective primary and secondary belt scrapers reduce carryback by 95—?9%, dramatically reducing dust from this source. A poorly maintained scraper system can contribute 20—?0% of total conveyor dust.