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Illustration courtesy of savRee Diagram of a basic Blake stone crusher.

As technology advanced from the middle of the 19th century, some newly patented machines, not designed specifically for mining or concentrating, were nevertheless readily adopted by the mining industry and met with enthusiasm. . One such very important – and often overlooked – invention is the jaw crusher, patented in 1858 by a man named Ely Whitney Blake.

Eli Whitney Blake was a native of Worcester County, Massachusetts, and nephew of Eli Whitney, inventor of the cotton gin. Blake had graduated from Yale in 1816, but dropped out of law school when his uncle, Eli, asked for his help in organizing and erecting an arms factory in Whitneyville, Connecticut. A talented mechanical engineer, in 1852 Blake was appointed to oversee the macadamism of the streets of the city of New Haven, which alerted him to the fact that there was no suitable machine for breaking rock. The lack of such a machine was one of the causes of production bottlenecks in the Lake Superior copper mines, where rock breaking was still done by calcination, which Georgius Agricola mentioned in his book “De Re Metallica”, first published in 1556. New Haven used a similar process for its road surfaces.

Blake’s solution was to invent what he called, simply, “a stone-crushing machine.” Powered by steam, Blake’s grinder had one fixed plate and one that pivoted at the top to give it the greatest movement. Rock was fed into the top of the crusher and gradually moved down to the discharge outlet at the bottom of the jaws. According to savRee, an engineering website, the V-shaped area between the two jaws is called the grinding chamber. As the space between the two jaws narrows towards the discharge outlet, the rock gradually shrinks.

Although they greatly increased efficiency, reduced time, saved money and labor, and were used in nearly every shaft where a mine had steam, they were rarely mentioned in annual reports of mining companies. Reports generally reported rock mined and then rock being processed at the pad plant, but rarely mentioned preliminary crushing. In 1900, Horace J. Stevens, in his book “The Copper Handbook”, in a Calumet and Hecla Mining Company report, writes:

“The well houses with inclined wells are of a uniform pattern. Each time the rock is hoisted from the mine to the top of the chamber shaft, where it passes through a ‘grizzly’, which allows finer rock to fall through, larger masses being reduced in the jaw type crushers with two openings by three legs.” After the preliminary crushing, Horace continued, on the lower floor there was another crusher, 18 x 24 inches, in each shaft, Stevens wrote.

According to author and publisher Thomas Rickard, the pitstone houses of the Quincy Mining Company had similar layouts. Discussing the rockskip hoisted to the top of the structure from the mine shaft, Rickard wrote:

“When the dumpster is unloaded, the contents fall onto a grizzly, made of fixed cast iron bars capped with a removable angle iron, the gaps being 2.5 inches wide. two wheels, then is transported to the rock breaker; it’s a quick way to move the pig rock pieces, and it’s a step up from the usual way of pulling on the ground.

Smaller pieces, he wrote, were thrown into the grinders.

As the grizzlies lay at a low angle, he wrote, some of the small pieces of rock came to rest on the bars, which were shoveled into the crushers.

Rickard said each of the “stone houses” was equipped with three Blake-type crushers. The largest had 18 x 24 inch jaws (the same configuration used at C&H), while the two smaller crushers each had jaws set at 13 x 20 inches. Masses of copper were placed under a drop hammer weighing 1.5 tons and having a drop of 20 feet.

providing an equivalent of 60 tons of feet. Copper, being malleable, would flatten or change shape after such a blow, knocking the clinging rock off the mass.

Stevens in 1899 wrote that at No. 3 Baltic Shaft was a “substantial” well-rockhouse, wood frame, steel-clad, 88 feet high. It was equipped with two Blake crushers configured, like those of the Quincy and the C&H, in 18 x 24 inches, driven by a motor “with 16 x 18 inch cylinders.”

Stevens also reported that well #4 had a “temporary plant, with a winch about 1,000 feet, raising a one-ton bucket.”

In fact, all the wells were opened with temporary equipment, he writes, which “are replaced, as the opportunity arises, by permanent buildings and heavy equipment.”

Choice of the word by Stevens “temporary,” seems to suggest that at the five Baltic shafts they were started with second-motion portable gear hoists. Usually second movement motors rotated a single drum.

A second motion gear hoist consisted of two motors, with a drum attached by means of a drum shaft, receiving its motion by means of one type of gears (double helix). Brake and reverse gears were operated by hand levers between the two cylinders.

Power, a weekly publication devoted to the production and transmission of energy, stated in its volume of December 28, 1909 that at that time the largest hoisting motors in the world were in the Quincy and Tamarack mines, at “Michigan copper country.” Both hoists were built by the Allis-Chalmers Company in the 1890s. As the publication indicates, however, while newer and more powerful steam hoists were subsequently designed and built, electric hoists have also designed, such as the electric hoist at the Sewall’s Point coal shipping terminal near Norfolk, Virginia, which was rated at 1,000 horsepower.

Although steam has indeed revolutionized mining in Michigan’s Copper Country, it was not steam alone that sparked the revolution. Innovations and improvements in the stamp mill and the mill necessitated larger steam engines and the boilers to power them. Jaw crushers, also steam-powered, helped Michigan mining companies stay competitive with new surface mines in the west. The machine drill, powered by steam-powered air compressors, cut more rock per shift than hand-drilling, and newer, more efficient steam-powered hoists could lift more rock, faster per shift. day than the old portable hoists. By the turn of the 20th century, mines in the Lake Superior region were fully equipped to compete with mines to the west – as long as the copper grade remained rich.

Graham Jaehnig holds a BA in Social Science/History from Michigan Technological University and an MA in English/Creative Nonfiction Writing from Southern New Hampshire University. He is internationally known for his writings on Cornish immigration to the mining districts of the United States.



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