A shipyard in New York harbour recently switched blasting abrasives to trial GMA ToughBlast™ garnet and discovered efficiencies across the operation.

Previously using slag abrasives, the shipyard had to contend with several key issues affecting their operational costs and productivity – dust, disposal of slag and scheduling abrasive delivery to keep up with production.

Furthermore, the blasting operations were mainly conducted at night due to high dust levels.

The shipyard used GMA ToughBlast™ garnet for blast cleaning two steel ocean barges with a surface area of 10,219m²(110,000ft²) to a commercial blast of SP-6 and achieved significant results.

Using GMA ToughBlast™ garnet, the shipyard experienced substantial savings of up to 70% in abrasive consumption. The total garnet consumption was only 250 tonnes compared to 825 tonnes of copper slag typically required for a project of this size. 

In addition, the reduced consumption rate also resulted in less downtime required to refill the blasting pots. Rather than refilling the eight-tonne blasting pot every 2.5 hours when using slag, the change to GMA ToughBlast™ garnet allowed workers to continue blasting throughout the night shift without interruption for refilling, which could then be completed by the day crew. 

As a further convenience, refilling the blasting pot during the day could be completed by bulk bags rather than two 25t bulk tankers of slag per day. The use of bulk bags also meant that regular flat-bed trucks could make the deliveries while production continued and to stay on top of deliveries. 

The result was an impressive increase in efficiency from each blaster covering 111m²(1200ft²) per night (using slag) to between 139 to 185m²(1500-2000ft²) per night using garnet. 

Furthermore, taking advantage of GMA’s used garnet recovery programme, each delivery vehicle was re-loaded with collected used garnet for return to GMA’s Fairless Hills processing plant. The easy management and removal of used abrasives reduced disposal costs to zero, completely eliminating the USD $150 per ton plus freight costs required to dispose of spent slag. 

Blast cleaning using GMA Garnet provides significantly lower dust emissions due to its inherent material toughness and rapid settling (high specific gravity). 

The lower dust emissions provide great improvements in operator visibility and safety on site while eliminating the constrain to only conduct blast cleaning at night due to the high dust levels created by slag.

By Jim Gooden & Trevor Gooden, Blastone