In the late 1800s, powered pneumatic drills were beginning to replace the hand-powered rotary drills that had been utilised in hard-rock mining since antiquity. This allowed rock mines to be explored and exploited more quickly and easily, making it profitable to mine marginal deposits. However, hand-powered drills continued to be used in small private mines throughout this period.
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The Role of the Drill in Rock Mining
During the late 1800s, most hard rock mining was achieved through blasting with dynamite. Holes were hammered or bored into a rock face by miners, who packed the holes with TNT. The resulting explosion would blast the rock face into smaller fragments, which could then be processed for ore. After removing the loose material from the mine, the miners would begin drilling the blasting holes into the newly exposed face.
Where there was room, miners preferred to make blasting holes by hammering large spikes into the rock using sledge hammers. However, it was more economical for mining companies to drive narrower tunnels through the rock, closely following the seams of ore. In many narrow shafts, miners had to drill blasting holes using hand-powered augers. These consisted of a spiral drill bit on a U-shaped crank handle. Drilling a hole into solid stone with such a tool could take hours.
Steam-powered pneumatic drills were utilised in mining as early as the 1850s. They were large piston drills which made holes by rapidly driving a steel rod or chisel into the stone, in the manner of a modern jackhammer. However, steam-powered drills were limited to mining operations near the surface, as the steam could not be pumped through long pipes or tubes without cooling and thus losing its power. Deeper shafts, where most of the mining actually took place, still relied on hand-powered tools.
Compressed-air drills appeared in mines as early as 1852, but did not become widespread until the early 1890s, when several technological innovations made them feasible for general adoption. Compressed-air drills were similar to steam-powered drills, but could be powered by air pumped down through long hoses from the surface. As these drills were used, they expelled compressed air, which helped cool and ventilate the work area and remove rock fragments from the hole being drilled.
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