Water mist binds dust
Processing, transferring and storing bulk materials, waste and recyclables are often associated with high dust generation. This can be very harmful to humans, detrimental to the environment and cause increased wear of machines and equipment.
Precondition for effective dust reduction is the fact that dust particles have an affinity to become attached to fine droplets of water and this affinity can be used to bind any dust contained in a processed or conveyed material. This can, however, only work providing the water is supplied with a sufficiently large surface area. The terz GmbH, a company based in Kirchberg/Hunsrueck, manufactures Nebolex® environmental systems – atomization systems for binding dust with water mist. In self-priming misting heads, the water is atomized into fine droplets and a jet of mist can be specifically directed to where the dust is generated (Fig.).
The system features a modular design, can be easily extended and consists essentially of four units. These are: the processing unit for the compressed air (compressor), two control units for controlling system as required and the fogging bars with misting heads to inject the water mist. The control unit can be use to control different sections of the installed system in line with requirements. This is important especially for large systems as not always all plant components, like, for example, belt conveyors or feed hoppers, are operated continuously at the same time. All relevant factors such as the quantity of material or outside temperature (danger of frost) can be recorded and taken into account by the system, enabling it to respond as needed. The system can be controlled with a PLC, relay control or manually. With the misting heads specially designed for dust minimization, which are arranged in fogging bars, dust can be effectively bound or suppressed at difficult places.
Wherever it is not possible to inject moisture directly into the material, one option is the formation of a horizontal or vertical curtain of mist. In this application the volatile dust absorbs moisture as it penetrates a mist barrier and then drops owing to the increased specific gravity. Typical applications are:
Loading and unloading systems
This system can be used for precise direction of the mist and generation of a mist curtain precisely where required. If the system is activated or deactivated by remote radio control, it is possible to mist the material for a defined time or the mist can be shut off manually. A curtain of mist can be generated at precisely the moment that the dust is generated. With the multiple increase in the surface area of the water the water injected amounts to just one to five per mil depending on the type of material processed. This can be important for further processing, e.g. in cement and asphalt production. The two variants for dust suppression can be easily combined.
If required, the system can be equipped with a diagnosis function, which includes a communication processor with a USB connection. The system presented here can be installed as a stationary system, e.g. in crushers at quarries, or operated as a mobile unit, for example in wheel loaders for material transfer. It is used efficiently in a wide range of industries.
Stand R 06