Three things to do when recycling expendable abrasive
Many contractors use expendable abrasive in a blast room situation. By expendable we mean Garnet, Slag, etc. Steel Grit, Aluminum Oxide, etc are not normally considered expendable abrasives.
Some try to re-use this expendable abrasive, and if you do, here are a few tips:
Keep it absolutely dry. Unless you are using a wet-blast machines, wet abrasive won't recycle
Recycle in batches. Unless you have a recovery system which automatically collects the spent abrasive and recycles it, it is more efficient to recycle several tonnes at once.
Use an airwash system to remove the dust properly. Sometimes we see blasters just getting shovel loads of dusty abrasive and shoveling/bucketing it back into the top of the pot. Best practice is to have an airwash to remove this dust before using it to blast again.
Dust doesn’t produce a profile; dust does not remove mill scale; dust does not remove paint; dust does not blast
Blasting with dust obviously creates more dust, causing the operator to be hindered from seeing what he is blasting, lowering production.
Dust will wear out metering valves, blast hoses and blast nozzles far quicker than abrasive will. The reason for this is there are obviously many, many more dust particles than there are abrasive particles because dust particles are so much finer. Small dust particles moving at high speed will wear out equipment faster than abrasive moving at high speed because there are far more particles.
Dust uses up the energy of compressed air. The important thing when blasting is to make sure that you are getting the maximum velocity of abrasive out of the nozzle. To do this, every bit of abrasive needs to be acted upon by compressed air. Compressed air is an energy source – the energy is imparted to the abrasive as kinetic energy. If you have dust in the abrasive you are putting the energy from the compressed air into the dust which is a waste of energy.