How Is Borax Mined?
Borax, which is also known as sodium borate and sodium tetraborate, is a powdery, white, boron-containing mineral used in detergents, cosmetics, fire retardants, anti-fungal compounds, insecticides and in the refining of gold and silver, among other uses. Of the 60 or so known boron-based minerals, borax is the most useful for commercial purposes. Almost half the world's borates are mined by Rio Tinto Borax in an open pit mine in Boron, California.
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Drilling
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The first step is to drill into the ground to remove samples of the ore. These are then tested to determine their purity. The deposit's location and composition are mapped out and used to decide the order in which different parts of the mine will be mined. Once engineers have decided where to dig next, drills are again used, this time to make blast holes.
Excavation
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Explosives are used to loosen the rock covering the deposit, called the overburden, and the ore beneath it. Once the ore and overburden are loosened, shovels the height of a seven-story building scoop rock and ore from the mine pit. The shovels dump this raw ore into trucks. Each truck load weighs about 80 tons---about the same as 40 cars.
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Transportation
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The trucks used to carry the raw ore are 20-feet-high, 40-feet-long and have 12-foot-high tires. Each truck can carry up to 240 tons of rubble. The trucks are so huge that they must be shipped to the mine in pieces and assembled on-site.
Crushing
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The raw ore is then crushed. Huge crusher machines grind the ore down to pieces about 1 inch in diameter. This increases the surface area, which aids refining, and also makes it possible to transport the ore to the refinery more easily. The ore is usually refined on-site, and carried from the crusher to the refiner on a system of conveyor belts.
Refining
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Once in the refinery, the raw ore goes through a series of processes that purify the borates to make them useful for industrial uses. The ore is first mixed with a combination of hot water and other minerals. The borates dissolve in this liquid, while other solids are removed. The liquid is then cooled, which causes crystals of borate to form. The liquid is next poured through filters and washed. Finally, the crystal of borate are dried using hot air, and sent for storage, packing and shipping.
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References
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