Pneumatic Transfer Conveying System
The conveying of fine dust down a four to six inch diameter pipe for distances up to 1500' allows the ability to remove dust from the dust collection system and separately convey the dust to a plant silo, yard silo, or crusher surge bin where a mechanical separator (cyclone) can deposit the dust and vent the conveying air to a local dust collector. This avoids re-entrainment by not returning dust to the belt.
Remember the 'end of run purge' discussed earlier (inAir-Cure's Approach to PRB Coal Dust Collection under the topic Greater Potential for Spontaneous Combustion in PRB Coal). The pneumatic transport will convey the surge of dust to an appropriate discharge point other than the conveyor belt. Eliminating both re-entrainment and 'end of run purge' dusting. Pneumatic transport also allows collectors to be located at grade or locations for easier maintenance access and to be more economical, eliminating costly structural supports to position collectors above conveyors for gravity spouting.
A caution on pneumatic conveying: there is no simple formula for engineering a system, for example, the sizing of a screw conveyor. It is more of an art than a science to achieve reliability in a pneumatic system design. Successful applications from our experience have produced very good reliability.