ORE PREP BEGINS WITH YOUR BLASTHOLE DRILL

            Ore prep begins long before it enters the crusher.   It even begins before it is dug out of the ground.  In fact, it begins when your blasthole drill starts drilling the blasthole pattern.  And, much of that depends on the drill you buy.  Buy the wrong one, and your ore prep costs can go up. 
            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 blasthole drill is operated by a fair operator, who is only 90% as efficient as a good operator, 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.