DriJet™ uses x-rays to measure the atomic weight of individual pieces of coal and rock, and precision air jets to separate the two fractions. It is an unusual mineral separation technology because it sorts not by specific gravity but by atomic weight.
The x-ray sensors can sample even a small chip of rock or coal hundreds of times to build a profile of the constituent elements inside. The volume of air required to make the separation is very small. For example an air table is a common specific gravity separation technology, and in comparison a DriJet uses 1/3 of 1% the amount of air. A DriJet 100 can sort 20,000 pieces of coal and rock in one second with an error rate of less than 1%.
DriJet technology uses little power and has few moving parts. It uses no consumable chemicals or water at all. It has a small footprint. It can inexpensively remove ash and sulfur from coal right at the mine face.