types of mining"elmanga"

Types of Mining

Placer

Placer mining involves any type of mining
where raw minerals are depostied in sand or gravel or on the surface and are picked up without having to drive, use dynamite or any other signifigant means. The word placer means "sand bank" in Spanish. Specific types of placer mining are panning, dredging, sluicing, using a Rocker, or just picking up what lies on the ground.

Hydraulic
Hydraulic mining involves high pressure water.
The water is

Operating hydraulic mining elevator and impounding works at North Bloomfield Mine

sprayed at an area of rock and/or gravel and the water breaks the rock up, dislodging ore and placer deposits. The water/ore

Hydraulic mining in Alder Gulch. Madison County, Montana.

mixtue is then milled. This is a very destructive way to mine and has been outlawed in most areas.
Hardrock
Hardrock mining entails diging into solid rock to fine minerals usually in their ore form (the metal plus oxygen). To do this,
miners used picks and shovels, rock drills,

dynamite and more. Miners dug either shafts that went straight down to follow ore bodies and veins, or tunnels which went somewhat horizontal into rock faces. Shafts usually had some sort of headframe (pictured left) standing above them to support the hoists. Shafts and tunnels were often supported with large timbers to prevent cave-ins. Most shaft or tunnel mines would eventually flood as they hit the water table and water would have to be continually pumped out. Sometimes there was so much water they had to abandon the mines.
Open Pit

Open pit
mines involve digging large open holes in the ground as opposed to a small shaft in hard rock mining. This method of mining is most often used with minerals like copper and molybdenum. Open pit mines are very large and devistate the surrounding landscape as can be seen in this picture of the Bingham Canyon Mine near Tooele, Utah. Mining operations of this scale were not done too often in the 19th century

Types of Hard Rock Mines

Tunnels
Hard rock mines usually fall into one of two categories, tunnels or shafts. Each involves digging and blasting deep into the bowels of the earth. Tunnel hard rock mines begin at the earth's surface

Tunnel Mine

and continue horizontally into the rock. Tunnels can extend for miles as they follow the ore. Most tunnels have many side tunnels, or even shafts that are sunk far back in the tunnel. These shafts are called winzes. Exploring Tunnel mines is very dangerous as it its dark and very difficult to see winzes. Many tunnels go back so far into the earth they tap into some of the earth's geothermal resources filling with gas that is toxic to humans. There is also the danger of cave-ins in old shafts that are no longer supported by the rotting wood timbers.
Shafts
A shaft is a whole in the earth that is dug relatively straight down. Shafts usually have some sort of headframe or large wooden or metal structure at the top of the shaft to support a hoist. Hoists are used to lower men and machinery into the mine and to haul

Looking down a Shaft

ore out. Many shafts have tunnels dug at different depths throughout the shaft. Getting too close to the side of an abandoned shaft can spell almost certain death. Many of the shafts extend thousands of feet into the earth.

Powering The Mines

Steam Engines
In the early days and in small operations, simple mule and man power was used for everything. As technology advanced, and operations became larger, the steam engine was introduced.

A

Steam Engine

steam engine consisted of a large boiler. The boiler (pictured here) was a very large cylindrical metal chamber in which steam was produced. Most boilers have either fire tubes or water tubes on the inside of the chamber. Either water was forced through these tubes (pictured below) and the rest of the chamber was filled with "fire" or water filled the chamber and the tubes were filled with the "fire". Wood, coal or coke was used to produce the "fire" or heat that was in turn used to turn the water to steam. From the boiler, the steam went to a cylinder much like a modern gasoline powered car's cylinders. Under pressure, steam forced its way into the cylinder depressing the piston. As the piston was depressed, it turned a crankshaft which could be used to power a hoist, air compressors or pumps.
Water(Hydro) Power
Wherever possible, water or hydro power was used. If the location of the milling site was near any kind of sizeable reliable moving water, a water wheel would be used to generate power. This water wheel would have many paddles on it and would be partially submerged in moving water. As the water flowed, it would cause the wheel to turn. The wheel was then connected to whatever was needed to be powered.
Diesel Engines
In the early 1900's, diesel engines began to replace steam engines because they could produce more horsepower using less space. Invented by a man named Rudolph Diesel in 1894,

Diesel Engine

the diesel engine was built on the idea that air could get hot enough from the pressure inside the cylinder to ignited the fuel. A diesel engine does not have a spark plug. It generates the heat needed to ignite its fuel entirely from the compression of air. To do this, the compression in each cylinder is about 3 times the amount found in a normal gasoline engine. Diesel engines were hard to start as these engines were placed in harsh and many times cold locations where mines were located. To counteract this problem, glow plugs were used. These are small plugs located in the cylinder that can be electronically heated up to ignite the fuel when the engine is cold. Diesel engines are still used today to produce power at mines.

Transporting the Ore

From the Mine to the Outside World
Once the ore was broken off the rock faces inside the mine, the chunks were shoveled into a transportation system to get it to the outside. If the mine was a shaft mine, the ore was shoveled into

Ore Bucket

an ore bucket which was hauled up to the top of the mine by a winch. This winch or hoist was usually powered by the

Hoist

steam or diesel engines and was also used to get the miners and other equipment in and out of the mines.

Ore Car

If the mine was a tunnel mine, the ore was shoveled into an ore car that ran on small train like track. The ore car was pulled on these tracks all the way out of the mine.
From the Mouth of the Mine to the Mill
Once the ore was at the mine entrance, it was transported to a mill for milling. The type of transportation used here depended on how far the mill was. Many mines had mills in the same town that were nearby the mine making transportation easy. Most of the time, ore was deposited into an ore chute that held tons of ore

Ore Chute

waiting to be processed. From this chute, the mill which was usually located below the chute to take advantage of gravity, took as much ore per hour as it could process. Sometimes the mines were located on steep cliffs or near the tops of mountains. In

Aerial Tramway Tower

these cases, an aerial tramway system was developed, much like a modern ski lift. The only difference is instead of carrying skiers on a seat the tramway carried ore in giant ore buckets. If the mill was located in another city or state, the ore was loaded onto sturdy wagons for transportation.
From the Mill on
Most mills were not able to concentrate the ore completely to the free metal. In other words, most mills located at the mines and townsites were not able to put a rock in one end and have a gold ingot come out the other. Their job was simply to concentrate the ore enough to save on the shipping. If the ore coming out of the mill was ten times more concentrated than the ore going in, then one wagon load of the processed ore would be equal to 10 wagon loads of the unprocessed ore. This could greatly reduce the riskiness and difficulty of shipping the ore as the ore wagons were a favorite of bandits.

Milling the Ore

Arrastras
When a full size stamp mill was not available, arrastras were used to crush the ore. Arrastras were small circular flat areas of land usually about 10-20 feet in diameter with a pole in the center.

Early Arrastra

Attached to the pole was a rod or line running out to a large heavy wheel. A horse or mule was usually attached to the end of the wheel area and would walk around in circles. As the animal walked, the heavy wheel would crush the ore underneath it. Arrastras were a crude way to crush large pieces of rock into much smaller and more manageable sized bits. In later years, iron arrastras (pictured on the right) replaced the wheel method.
Stamp Mills
Stamp Mills were far more advanced than the early arrastras although they both performed the same function. Stamp mills ranged from one stamp on up to twenty or even fifty stamps all operating together.

5 Stamp Mill

Each stamp was a large piece of solid iron or other metals attached to a long shaft. These shafts were usually attached to a cam with the other stamps if there were more than one. This cam had usually had a wheel on its end that was driven by a belt system. A steam engine was usually used to turn this wheel which lifted the stamps and dropped them with all their weight on the rocks that were to be crushed. Stamp mills would run 24 hours a day and as one can imagine, are extremely

Small 3 Stamp Mill

loud. They also tend to shake the ground as they are dropped which can make it feel like there is a continuous earthquake.