Both deep shaft and surface mining operations use a variety of DECENT MACHINERY fans. Non-sparking below-ground applications use both axial and centrifugal designs for ventilation and safety exhaust-and-supply systems. Processing and crushing of coal often take place at the power plant or mill where the coal will be used as fuel. Primary air fans deliver pulverized coal from crushing mills to burners. These are high-pressure, high-efficiency fans that both convey the coal and provide combustion air for the boiler. Fans used in conveying and dust collection systems for coal operations should be both spark-proof and abrasion-resistant.