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GETTING THE MOST FROM YOUR
BLASTHOLE DRILL
Blasting and drilling article by
Harold Hough April/May 2008
When
thinking about efficiency, mines often focus on haulers, shovels, and loading
cycle times. However, there are other types of heavy equipment that can improve
the mine’s overall efficiency. One example of an overlooked piece of equipment
is the blasthole drill.
Yet, the blasthole drill has a
major impact on efficiency. Before a mine digs or processes the ore, it hast to
be broken up by blasting. Consequently, a mine can make the perfect choices on
the type of shovels and haulers to buy, but be wasting its money if the
blasthole drill is broken or inefficient.
Few pieces of heavy equipment
undergo harsher conditions than the blasthole drill. The drill operates in a
hostile environment of its own creation by cutting, grinding, and pulverizing
rock; and then spewing it up to the surface. Above ground, the drill’s derrick
must rotate the drill and feed the pipe, so the structure is subject to heavy
loads and twisting. As a result, even with good maintenance, a drill will
require maintenance 2% - 3% of the time.
BUYING THE RIGHT EQUIPMENT
Some of the factors for buying a
blasthole drill are the diameter of the blastholes to be drilled, the depth of
the drillholes, the amount of drilling, and if angle drilling is required.
Another factor is whether to buy a diesel or electric drill. The electric drill
costs less to operate and requires less maintenance, but is less mobile due to
the cables leading back to a power source. If drilling is restricted to a small
area, an electric drill is probably the best choice.
For mines that need mobility, a
diesel is the best choice since it’s self-contained. However, the trade-off is
higher operation costs and more maintenance. According to heavy equipment
experts, a diesel drill requires rebuilding every 2,000 hours of operation. If a
mine works two eight hours shifts a day, five days a week, then the drill will
require rebuilding every six months. Since the drill will be out of service for
one to two weeks, a mine either needs to slow operation or have a second machine
to pick up the slack.
A diesel rotary drill will
consume 10% to 12% of its initial cost in parts and labor in the first 2,000
hours of operation. Each succeeding 2,000 hours may see these costs rise to 15%.
If you don’t focus on scheduled maintenance, those costs can go up.
Another factor to consider is the
heavy pounding a blasthole drill undergoes. Mines can initially save money by
buying a blasthole drill with a lighter frame. However, as time goes by, this
light structure will develop cracks as the drill encounters tough conditions. In
the long run, equipment with more metal will last longer.
MAINTENANCE
Maintenance practices must be
considered when buying your equipment. If a mine operates on a continuous basis,
more equipment should be purchased so individual pieces can be pulled out for
scheduled maintenance. If the mine has maintenance days like Friday or Saturday
where mining stops, the extra drills aren’t necessary. If the mine doesn’t
have a good maintenance program, less money should be spent on equipment with
the remainder going to instituting a good maintenance program.
Vendor support is also critical
to keeping equipment running. Some drills made in other countries are cheaper,
but spare parts must be ordered from the factory and the delay may cost several
weeks in down time. A supply warehouse in the United States can limit the
problem.
Another way to maximize your
blasthole drill investment is to have experienced operators and limit delays. If
a fair operator, who is only 90% as efficient as a good operator, operates a
blasthole drill and the mine wastes 6 minutes a hour in interruptions, the
overall efficiency of the drill is only 81%. In other words, a drill team that
has the capability to produce 10,000 tons of rock per shift would only be
producing 8,100 tons, even though the mine is paying for 10,000 tons.
If you properly care for your
blasthole equipment and employ good operators, you will have the time necessary
to focus on other facets of the operation. In the long run, the small amount of
attention spent on your blasting operation will make everything else more
efficient.
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