Zinc ore was known to humanity long before pure zinc was first isolated and the metal received its modern name zincum. Zinc ore became one of the main components of brass (an alloy of copper with zinc), from which jewelry, coins, dishes, figurines, and other decorative objects were made. The first brass products found in northern modern Iraq date to the 3rd millennium BCE; later ones discovered by archaeologists in Palestine date to the end of the 2nd millennium BCE.
Metallic zinc in human history
Pure zinc first began to be manufactured in India roughly from the end of the 12th century. The production process was similar to tin melting: zinc ore together with charcoal was heated in closed refractory vessels, as a result of which zinc vapors were released that condensed in a special vessel on cooling. In 1374 in India zinc received the status of a new metal (at that time the 8th in count), which gave an impetus to developing its production and sale. Until the end of the 18th century India remained the main importer of the metal and kept fairly high prices for zinc.
In the 17th century manufacture of metallic zinc began in China. Like their colleagues from India, Chinese scientists mixed zinc ore with charcoal in closed vessels, but they did not collect zinc vapors. Vessels with ore and charcoal were stacked in a pyramid shape and heated red-hot, then cooled. As a result pure zinc collected inside the vessel as solid ingots.
In Europe successful experiments with zinc began only in the 13th century. German scientist Albertus Magnus, unfamiliar with zincum as a metal, found a way to increase zinc content in brass. When producing the alloy the hot mass was sprinkled with broken glass, which prevented formation of zinc vapors and thus increased its content in the final product.
Zinc was designated as a new metal in Europe in the 16th century by Swiss alchemist and natural scientist Paracelsus. But European scientists were able to obtain zincum in pure form only in the 18th century. In 1743 British metallurgist William Champion opened the first plant in Europe for melting metallic zinc. After becoming familiar with the metal production technology in China, the scientist improved it by changing the design of the vertical melting furnace. His method made it possible to melt up to 400 kg of pure zinc in less than 72 hours.
By the end of the 18th century a new method of obtaining pure zinc was developed that did not require cooling the metal and made it possible to save a significant amount of charcoal. Smithsonite — zinc carbonate — was first used as raw material, then sphalerite — zinc sulfate, which until then had been one of the wastes in mining silver minerals. Exactly the use of sphalerite gave an impetus to expanding zinc production. The main drawback of this method was release of sulfur gases formed when heating the sulfate. But later they learned to convert them into sulfuric acid, which allowed zinc plants to reduce environmental pollution.
Use of zinc in industry
As metallic zinc became more available, its commercial use also grew. Already by the beginning of the 19th century production of cold-rolled zinc sheets (at 100–150°C) was mastered, which gave industrial enterprises the ability to mass-produce zinc roofing elements, downspouts, and even garbage bins.
At the same time research was widely conducted in galvanizing various metals. The first patent in this field in 1837 was received by French engineer Stanislas Sorel, who developed a method of applying molten zinc to protect iron from corrosion.
Today more than 50% of mined zinc is used precisely for galvanizing, protecting various parts and metal structures from corrosion that are not subject to strong mechanical effects in service.
In addition, pure zinc is used in producing alloys to lower their melting temperature, and also as the main material for manufacturing negatively charged electrodes of accumulators and batteries. Zinc oxide is part of some paints, including zinc white, and is used in producing artificial leather, rubber products, glass and ceramics, and also in pharmaceuticals as an anti-inflammatory and disinfectant.
