Steel shot vs. garnet

Garnet is a group of natural silicate minerals used as a blasting abrasive. The type used is called almandine: a natural product, chemically inert, with no toxic components and no quartz.

That absence of quartz is its great advantage: unlike silica sand, garnet releases no free silica, so it carries no silicosis risk. Its hardness and angular shape make it an aggressive, good-cutting abrasive. On the downside, it is a single-origin mineral and can be recycled only about 5 times, far fewer than steel abrasive.

Steel abrasive is produced by melting, with controlled chemical composition. The process yields rounded particles —steel shot— which, when the larger diameters fracture, give rise to steel grit.

In jobs where it replaces garnet, sand or aluminum oxide, steel grit is used almost exclusively, sometimes with a small percentage of shot: the angular particle has edges and points and, on

For the same job, garnet consumes 230 kg versus 5 kg of steel abrasive —about 46 times more— because steel is recycled hundreds of times and garnet only a few. Add to that roughly 25% higher cleaning efficiency (20 vs. 16 m²/h) and far less dust.

Used with the right equipment and conditions, steel abrasive is more advantageous than garnet for blasting in enclosed spaces. The reasons:

• Higher productivity (~25% more efficiency), with lower labor and energy cost.
• Far lower abrasive consumption (5 vs. 230 kg in the test) and lower process cost per m² cleaned.
• Less waste and dust generation, cutting waste-disposal cost by up to ~98%.
• Lower investment in dust-collection systems and less wear on nozzles, hoses and equipment.
• Better work quality (consistency, roughness and cleanliness) and better conditions for the operator (improved visibility).