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Archive for October, 2012

mucker

Mucker machine that runs on compressed air (Old Hundred Mine).

As my tour through Colorado’s mining towns has progressed, I’ve become much more knowledgeable about hard rock mining techniques. I created a post on basic terms of the parts of a hard rock mine and the phases of its development previously; now, it’s time to learn the terminology of the daily lives of the miners and their 12-hour shifts underground. Since these terms and techniques are common to all hard rock mines, I’ll explain them now before moving on to the second half of my day in Ouray and Telluride. That way, as I describe the specific mine tours, I’ll only have to mention those things that are unusual about each tour.

miners using a jackleg

Miners using a jackleg drill.

Each mine generally had two shifts of 12 hours each. The miner’s shift would begin by reporting to the change room, where they would put on their miner’s helmet (at first a stiffened felt hat, later a helmet with a carbide lamp) and other gear, then they would line up for the hoist to lower them down into the mine shaft in the skip, or man cage. This process would take about an hour. Different miners had different jobs; newly hired men would work the face, more experienced men would run the hoist or set up the dynamite charges and fuses, or work inside the mine as blacksmiths to keep the tools sharp.

Single jacking

Single jacking. The miner would relax his grip at the end of each swing to prevent muscle fatigue, and the jack (chisel) was rotated 1/4 each hit to prevent binding.

Old time miners would single jack the face of the ore body using a chisel and an eight-pound hammer and just one candle. Teams of two men would double jack the face: one man would hold the jack and turn it a quarter turn as the second man would hit the jack with a sledge hammer. In the darkness of just one candle, all the hammer man had to see to aim at was the single slightly reflective spot of the smashed metal at the end of the jack.

jackleg drill

Jackleg Drill (San Juan County Museum).

Eventually pneumatic drills replaced the jacks and hammers, driven by a large air compressor just off the change room at the mine’s entrance. Hoses snaked into the mine to drive the drills. Some mines used tanks of compressed air that were filled up each shift and driven on the tram into the mine. These first drills were called jacklegs because they were set up on a portable leg that could be angled into the face. Instead of a rotary motion, the drills used a hammering motion to pound into the hole. They were also called widowmakers because they put out a lot of dust that got into the miners’ lungs and caused a disease called silicosis, similar to the black lung of coal miners. The silicon dioxide dust would act like glass fragments to cause scarring in the lungs, and after a year or two of mining with a widowmaker, a miner would be “rocked up” and unable to work. They usually died within six months or so.

jackleg instructions

Diagram of how a jackleg drill works (Hard Tack Mine).

Eventually someone thought of putting a hole through the center of the drill iron and pumping water through it to mix with the dust and make a slurry. This created quite a mess to transport out of the mine, but it did control the dust and extend the miners’ lives.

Drill hole pattern

Pattern for drilling holes at the face. The center holes were left open so that the rock would fracture inward. The bottom charges went off last and lifted the rock up and out from the face.

Whether by hand or with a pneumatic drill, the miners would drill a pattern of holes in the face. Each mine used a slightly different pattern, but they all had the same purpose. Once done, dynamite was placed in each of the holes except the center one and fuses with exact lengths were attached so that when the dynamite was exploded, it would start in the first circle out from the center, which would break inward toward the empty center hole. The next ring of holes would explode a millisecond later, then the next, and finally a row of holes on the bottom would explode and lift the fractured rock up and out of the face. These shots were done at the end of a shift, so that the air would be clear when the next shift came in.

mucker instructions

Instructions for running a mucker (Hard Tack Mine).

The new shift would remove the fractured rock, a process called “mucking.” At first it was done by hand with shovels, loading the rocks into ore cars and pushing them to the hoist or out of the adit by hand. Mules were sometimes used, but it was hard hoisting them down into the shaft. They had to be trussed up to get them down, and they would stay in the mines, eventually going blind in the darkness. Electric trams were invented to replace the men and mules. Mucking machines that ran on air were also invented that would be pushed to the face on newly laid tracks, then used to scoop up the rock and lift it into an ore car behind. Another device called a slusher acted as a dragline on cables to pull ore away from the face where it could be more easily loaded. Once the rock was mucked, the miners would eat lunch, then begin drilling the holes for the next shot.

mucker diagram

Mucker operation illustration. The hopper is driven by a chain drive ran off of compressed air.

This was the round of work at the face, which was the active area of a vein going basically horizontally. When they reached the ore bodies, they would follow the ore body up and down from the horizontal levels. This process was called stoping, and it required a different type of drill, called a stoper. It was longer and designed to drill vertically upward. The ore body would be followed in all directions and a chamber would result, with sets of timber emplaced as platforms. The miners would work their way up, building more timber sets and raising the stoper higher and higher. The ore would fall down to the bottom of the stope, usually into a wooden bin with chutes from which the ore could be emptied into an ore car.

stoper diagram

How a stoper works (Hard Tack Mine).

To access the ore body, horizontal levels were blasted at 100-foot intervals down the main shaft, which then proceeded to the veins or stopes. Tunnels heading perpendicularly away from the levels were called drifts. Sometimes to get water or ore out of a mine, a long horizontal tunnel was blasted from the outside to a lower level. This was called an adit. All of these longer reaches were done with a type of drill called a drifter or a Leyner drill. It was sometimes mounted on a vertical column anchored into the rock with a long tray that moved the drill along into the face. Several of these could also be mounted on moveable platforms to lower down a shaft in order to extend the shaft deeper or they would be mounted horizontally to lengthen a level. The holes were often longer (up to 30 feet) so that more rock could be removed at a time from a single blast, and the tunnels were often larger than the drifts that accessed the ore.

leyner drill

A Leyner or drifter drill, for making deeper holes. Several of these could be attached to a platform for drilling a pattern for a drift or a shaft (San Juan County Museum).

So it would progress from shift to shift, 24 hours a day, seven days per week except holidays (Fourth of July and Christmas). Miners in remote camps would work for two week straight and get paid, then go into town for a weekend and blow it all on food, drink, gambling, and other pursuits. They would report back to work broke the next Monday.

Miners came from all over; many were from Cornwall England where they had worked in the tin mines. The Cornish tended to save up their money in order to send for their cousins and other family members to join them. These “Cousin Jacks” were hired on as soon as openings occurred at the mines. Given the prevalence of accidents and silicosis, openings were fairly frequent. The Cornish brought a number of mining terms as well as superstitions with them. The most common was the belief in Tommyknockers, small elf-like creatures that inhabited the mines and communicated with the souls of dead miners. When you heard the Tommyknockers tapping in the mine with their small hammers, it meant someone would soon die and the Cornish would refuse to go anywhere near that part of the mine. Small leftover food morsels or pieces of rich ore were left as gifts to appease the Tommyknockers.

Leyner operation

How a Leyner drill operates (Hard Tack Mine).

Those who managed to survive for several years in the mines as young men would eventually be unsuited for work inside and would have to find work topside or elsewhere (being in your mid-twenties was considered old). The daily wage of three dollars was actually considered pretty good pay back then, but eventually miners unions formed which increased the pay, provided more days off, and reduced the shift times to eight hours.

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