Gold and its uses
Gold and its uses.Gold's great virtues of malleability, ductility, reflectivity, resistance to corrosion and unparalleled ability as a thermal and electrical conductor mean it is used in a wide variety of industrial applications consuming close to 300 tonnes annually.
Gold (Au, from Latin "Aurum" (World Book Dictionary) is the most non-reactive of all metals -- it is benign in all natural and industrial environments. Gold never reacts with oxygen (one of the most active elements), which means it will not rust or tarnish. Gold is among the most electrically conductive of all metals. Since electricity is basically the flow of charged particles in a current, metals that are conductive allow this current to flow unimpeded. "Gold is able to convey even a tiny electrical current in temperatures varying from -55� to +200� centigrade." (Gold Institute) Gold is the most ductile of all metals, allowing it to be drawn out into tiny wires or threads without breaking. Consequently, a single ounce of gold can be drawn into a wire five miles long. Gold's malleability is also unparalleled. It can be shaped or extended into extraordinarily thin sheets. For example, one ounce of gold can be hammered into a 100 square foot sheet.
Gold is the most reflective and least absorptive material of infrared (or heat) energy. High purity gold reflects up to 99% of infrared rays. Gold is also an excellent conductor of thermal energy or heat. Since many electronic processes create heat, gold is necessary to transfer heat away from delicate instruments. Gold alloy is the most tenacious and long-performing material available for protection of these temperatures.
Geologists use the latest technology such as satellite surveys and geochemistry to locate an ore deposit. Computers are used to design the mine, which requires precise and accurate measurement of the ore deposit. Construction begins following the lengthy process of receiving permits. As holes are drilled for blasting, samples of ore are examined to determine grade and metallurgical characteristics. The broken rock is marked by type for efficient processing. Based on its metallurgical makeup, a dispatcher directs truck operators to deliver the ore to the correct processing location.
Low-grade ore is roughly broken into small chunks and placed on carefully lined pads where a dilute cyanide solution is distributed over the surface of the heap. The solution percolates through the heap and the cyanide dissolves the gold. This solution containing dissolved gold is then collected. Refractory ore containing carbon is roasted to over 1,000 degrees Fahrenheit, burning off the sulfide and carbon. The product of this process is an oxide ore, which is routed to the leaching circuit. Oxide ore is sent directly to the leaching circuit where cyanide dissolves the gold. Sulfide refractory ore without carbon is oxidized in an autoclave to liberate the gold from sulfide minerals, then it is sent to the leaching circuit. Treated, high-grade ore is leached with cyanide.
The gold is absorbed out of solution onto activated carbon. The remaining cyanide solution is...
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