Zinc is a blue-grey metal which can be found abundantly in the earth's crust. Being highly reactive, it typically occurs as sulphides with other metals such as lead, copper, silver and gold present and readily forms alloys with metals including copper, aluminium and magnesium.
It has been in use for thousands of years and its main application is in galvanising although it is also an important metal for our immune systems.
Zinc is mined primarily from the ore Sphalerite (Zn,Fe)S, a zinc sulphide. Zinc is a chalcophile, such that it bonds with sulphur in highly soluble sulphides and rapidly oxidises when exposed to air. Within the oxidised area of zinc deposits is the commonly occurring zinc carbonate or calamine, formed though the alteration of zinc sulphide, from which zinc ore can be found.
More than 95% of global zinc is produced from Sphalerite. Extraction of zinc from the ore is largely done in two steps 1) mining ore to produce a concentrate at the mine site and 2) processing concentrates to produce refined zinc at a smelter.
Zinc is primarily used for its corrosion resistance in galvanising which accounts for approximately half of global zinc consumption. The electroplating process involves the formation of a protective layer of oxide and carbonate as zinc is highly reactive and corrodes when in contact with the air. This attracts oxidation away from the material it is applied to whilst also creating an anticorrosive coating to prevent materials from weathering. Galvanised materials (commonly iron and steel) are used extensively in transport, construction and appliance manufacturing purposes.
Among the best known alloys is brass - having a zinc content of 10-50% and between 55-95% Copper. This was one of the earliest uses of zinc and even today is still used in musical instruments, decorative items and tubing. It has a strong resemblance to gold and is cheaper than copper. Other alloys include nickel silver, and solder which is formed by combining with lead and tin to join metallic surfaces. Metallic zinc is also used in dry cell batteries, die-casting (the process of creating molds from molten metal through pressure injection techniques), roof cladding and in the production of zinc oxide. This is commonly found in commercial products as pigment in sunscreens, cosmetics, textiles and supplements. Trace amounts of zinc are also essential to maintain healthy immune systems which can be obtained from foods such as lean red meat and whole grains.
Copper is a highly ductile semi-precious metal with high thermal and electrical conductivity and excellent corrosion resistance, finding extensive use in construction and appliances.
Copper is very efficient in transferring electrons to transport electricity. By far the most common application is in moving electrons, be it in electricity transmission and distribution or home and appliance wiring. It's suitability for a variety of industrial
purposes has expanded through the formation of alloys with as many as 400 existing compositions.
Copper compounds are predominantly extracted from sulphide deposits of chalcopyrite (CuFeS2), chalcocite (Cu2S), oxides and bornite (Cu5FeS4). Secondary minerals closer to the surface altered by oxidation may commonly be found as salts with striking blue-green colours. Copper also occurs within carbonate ores and more rarely in its native state. Most deposits are developed using open-pit mining methods as copper oxide deposits tend to be situated close to the surface above larger sulphide deposits underneath. Types of Most copper ores contain only a small percentage of copper with grades varying from 0.3% for open-cut mines to 2.0% for underground mines.deposits are classified on the basis of how they form; with Porphyry copper deposits being the most important, yielding two-thirds of the world's copper. Due to copper's high reactivity, copper deposits often host gold, silver and molybdenum, which are recovered as by products.
This occurs in three stages- beneficiation, smelting/leaching and refining. Copper is mined predominantly using the open-pit method for lower-grade deposits close to the surface and is most practical for large tonnages while other mines use underground mining.
Copper is very efficient in transferring electrons to transport electricity, which makes it highly preferable for wiring and power cables found in buildings and consumer appliances. It also has uses in electrical goods, specifically the wiring for TVs and mobile phones and in industrial machinery as a heat exchanger. Because of its high corrosion resistance, copper and its alloys are also used for the construction of gas and water pipes. Copper also possesses inherent antimicrobial properties and is an effective touch surface in schools and hospitals to minimise the spread of bacteria.