Consumption & Production
The tightly screened sizing of GMA Garnet ensures
a maximum number of grains unit weight. Blasting
speed (and hence, total job time) is a result of
number of impacts on the surface. The greater number
of grains impact the surface, the more area can be
covered in less time. GMA Garnet 30/60 Mesh contains
approximately 11.00 Million impacting grains per kg
of abrasive (5.0 million per pound) compared to the coarser slag or sand of
20 Mesh with only 1.00 Million grains per kg (.5 million per pound).
Depending on the application, this results in up to
twice the cleaning rate with GMA Garnet, using 1/3
the abrasives compared to other conventional
abrasives.
Dust Levels
GMA Garnet grains are among the hardest and
toughest minerals known to man. The unique geological
history of the grains has ensured that only the
toughest have survived.
GMA Garnet therefore has a very low friability.
The breakdown rate on impact is low enough to allow
multiple recycles. Because of the high density and
high specific gracity, rebounding GMA Garnet grains
fall rapidly to the ground close to the blasted
surface.
GMA Garnet therefore produces virtually NO DUST
which provides for excellent operator visibility,
minimum contamination of adjoining work areas and a
clean and healthy environment.
In comparison, Slag is quenched from its molten
state with cold water (in some cases seawater) and
crushed, giving each particle a glassy brittle
structure with distinct fracture lines. Upon blasting
impact, the slag particle shatters into minute
particles resulting in the generation of high dust
levels which become airborne due to their small size
and low specific gravity.
Likewise, silica sand is very brittle with most
grains disintegrating on impact causing excessive
levels of siliceous dust which is a major health
hazard and serious environmental pollution.
Surface Quality
GMA Garnet grains properly clean and scour deep
into cavities and rust pockets of the steel surface
easily achieving an SA3 quality finish, free of
embedments and free of excessive peaks. Because of
the tight grin size distribution, a surface profile
of 50-75 microns (2-3 mils) with a very large number of peaks
per unit area is achieved uniformly all over the
blasted surface. An extremely low chloride content
and no sulphur contamination insures the blasted
surface will provide an ideal base for any subsequent
coating application.
Steel surfaces blasted with coarser and angular
slags are left with particles impregnated into the
steel surface. There inclusions, up to 500 particles
per square inch, can be the cause of premature
coating failure. Coarser and more angular slags
produce excessive peaks and troughs and often fail to
clean deep into cavities, leaving behind rust pockets
that become corrosive cells.
Environmental Health and Safety
GMA Garnet is a totally natural product, free of
heavy metals or any toxic components. Copper
slag/nickel slag etc. are waste-products of the metals
refining industry and frequently contain unacceptable
levels of toxic heavy metals such as lead, copper,
zinc, arsenic, cadmium, etc. Silica sand has been
banned or restricted as a blasting abrasive in many countries around the
world since its fine dust can cause silicosis, a deadly lung disease, and
it has been linked to lung cancer.
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