Blast hole drilling is used most frequently in the mineral exploration industry. The drill uses a pneumatic reciprocating piston-driven "hammer" to energetically drive a heavy drill bit into the rock. The drill bit is hollow, solid steel and has ~20 mm thick tungsten rods protruding from the steel matrix as "buttons". The tungsten buttons are the cutting face of the bit. The cuttings are blown up the outside of the rods and collected at surface. Air or a combination of air and foam lift the cuttings. The use of high-powered air compressors, which push 900-1150 cfm of air at 300-350 psi down the hole also ensures drilling of a deeper hole up to ~1250 m due to higher air pressure which pushes all rock cuttings and any water to the surface. This, of course, is all dependent on the density and weight of the rock being drilled, and on how worn the drill bit is.
UsedRigs.com can help you find the blast hole/ air rotary used drill rig to fit your application whether it be a DM45 or Atlas Copco ROC L8. Don't forget that we offer the complete package with pipe, DTH hammers, and bits. Buy a used drill rig here, and also get the whole package!