Safe, Efficient, and Clean Operation of Belt Conveyors

Belt conveyors are among the most commonly used piece of equipment at mineral processing operations. A conveyor, and the associated transfer points, can generate significant quantities of hazardous debris and respirable dust. Operations must control these emissions by containing, suppressing, or collecting the dust and debris mechanically, either before or after it spills or becomes airborne, giving special attention to transfer points.

A conveyor belt consists of many different parts as seen in Figure 1.

Figure 1 - Basic components of a conveyor belt. 

There are three primary root causes for hazardous debris or fugitive dust emissions associated with conveyor belts: spillage, carryback, and airborne dust (Figure 2). Control of all three primary dust sources is necessary to eliminate hazardous debris and fugitive dust emissions.

Fig. 2 - Types of fugitive dust emissions and debris from conveyor belts 

Controlling Material Spillage

Material spillage from a conveyor belt is caused by a lack of material control, either at a transfer point or along the transfer route. Spillage along the transfer route is generally associated with carryback.

Carryback

Material that sticks or clings to a conveyor belt after passing over the head pulley is called carryback. Carryback tends to fall from the belt as it passes over return idlers. This creates piles of material that require clean-up, which can increase worker dust exposure. Also, respirable portions of carryback can become airborne and increase fugitive dust exposure levels. The goal is to remove carryback before it is released into the air and becomes a source of contamination to the workers or creates piles of material that require clean-up.

The primary means of controlling carryback is to clean the belt as it passes over or past the head pulley (i.e. shortly after material is discharged from the belt). The two most common means of cleaning a conveyor belt of carryback are to mechanically "scrape" the belt via scrapers or brushes or to wash the belt.

Water Sprays for Prevention of Airborne Dust

Wet spray systems, the use of water to control dust, may be classified into prevention applications and suppression applications. When properly designed and installed, water sprays are a cost-effective method of controlling dust from conveyors. The most common and effective practice for conveyor sprays is to wet the entire width of product on the belt.

To discuss this topic in greater detail, contact the experts at Process Systems & Design. They'll be happy to share their decades of experience and knowledge with you.

www.processsytems.com
info@processsystemsdesign.com
(410) 861-6437

Safety Video: Refinery Plant Explosion Animation

Brought to you as a courtesy of U.S. Chemical Safety and Hazard Investigation Board (CSB.gov) and Process Systems and Design (http://www.processsystemsdesign.com).

Video reviews the circumstances that led up to a 2015 explosion at a refinery in Torrence CA.

Process Systems and Design is a team of technical and business experts across a spectrum of industries who specialize in all aspects of process control and material handling equipment design, construction, and support. They can be reached by visiting http://www.processsystemsdesign.com or calling (410) 861-6437.