Dust is a major problem at many mining and quarry operation. It can cause health problems, and damage equipment. In addition, it reduces visibility and makes working difficult. Bulk visibility is one of the measurements OSHA and many other international and state safety departments use to determine if dust is not being adequately controlled.
Controlling dust is a common application in which BETE nozzles by Spray Nozzle Engineering are used. Dust control can take many forms.
The two main categories are preventative and symptomatic:
Preventative dust control stops dust before it becomes a problem. Wetting piles and roads would be considered preventative dust control. Another often-overlooked method of prevention is controlling dust in process. This can be done by adding a small amount of water, ore to aggregate or primary crushed material that is likely to produce dust as it moves through a process.
Symptomatic dust control is dealing with dust once it is already airborne. This is usually only done when it is not practical to control dust preventatively. One example would be filling dump trucks from a pile with a loader. It is not practical to soak the pile such that the entire pile is damp, but a few well-placed nozzles around a filling point can reduce dust production significantly.
Spray Nozzle Engineering technical representatives have worked with the engineering and environmental departments of many plants and mines where this is a problem, and have been able to offer successful solutions for various situations. With this experience, we have come up with the following guidelines to aid in the selection of appropriate nozzles:
Case 1: Conveyor Transport
Adding approximately 13.6 litres water per ton of crushed rock (1.5 per cent by weight) could greatly reduce the amount of dust generated during a process. This ratio seems to produce ideal results, controlling dust without creating mud or soaking the conveyors. This is best accomplished by using an appropriately sized 90 degree flat fan nozzle from our NF Series.
Case 2: Symptomatic Control
BETE was the inventor of the low clog pigtail-spiral nozzle for mining called the TF Series. BETE’s TF Series is an excellent nozzle for airborne dust suppression. Generally, the TF6, TF8, or the TF10 is used for the best effectiveness. If spacing must be wider, or significant winds are anticipated, larger sizes may be used. There is some compromise between effectiveness and wind sensitivity, as finer droplets perform better, but are more sensitive to the wind. In many applications, a BETE spiral can be more effective outdoors in arresting dust than a fog cannon, especially where wind, drill and evaporation are a major concern.
Case 3: Water Truck
Our FF Series fan nozzles are quite popular for water trucks when coverage of a very wide area is necessary. In this type of application two ¾” FF 500 nozzles on either corner of the truck can make quick work of very large areas (50′ wide or more). For single lane wetting or smaller areas, appropriately sized smaller FF or NF nozzles do well.
Another effective use of a water truck is for wetting dirt or rock piles, which may produce dust. This can be done with a larger SC Series nozzle. This nozzle can spray an area to a height of approximately 7.62 metres.
Case 4: Crushers and process plant
Spiral nozzles are the most commonly used nozzles to remove airbone dust as they provide a very fine droplet size at reasonable pressures. Recirculated water can be used with spiral nozzles for dust control due to the low clog design of the nozzle. The BETE “L” Series is the world smallest spiral nozzle. Used around crushing plants and mills, the “L” Series can provide effective control of the fine rising dust without the added issue of blockage or need for regular maintenance checks as with other styles of fog nozzle.
Accessories: Spray Nozzle Engineering can assist with a new range of quick attach nozzle systems for kit-form pipe installations, as well as pipe saddles and more; to save time and money.