Nickel

Nickel is a chemical element, with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. It is one of the four elements that are ferromagnetic around room temperature, the other three being iron, cobalt and gadolinium.

The use of nickel has been traced as far back as 3500 BC, but it was first isolated and classified as a chemical element in 1751 by Axel Fredrik Cronstedt, who initially mistook its ore for a copper mineral. Its most important ore minerals are laterites, including limonite and garnierite, and pentlandite. Major production sites include Sudbury region in Canada, New Caledonia and Norilsk in Russia. The metal is corrosion-resistant, finding many uses in alloys, as a plating, in the manufacture of coins, magnets and common household utensils, as a catalyst for hydrogenation, and in a variety of other applications.

History
Because the ores of nickel are easily mistaken for ores of silver, understanding of this metal and its use dates to relatively recent times. However, the unintentional use of nickel is ancient, and can be traced back as far as 3500 BC. Bronzes from what is now Syria had contained up to 2% nickel. Further, there are Chinese manuscripts suggesting that "white copper" (cupronickel, known as baitung) was used there between 1700 and 1400 BC. This Paktong white copper was exported to Britain as early as the 17th century, but the nickel content of this alloy was not discovered until 1822.

In medieval Germany, a red mineral was found in the Erzgebirge (Ore Mountains) which resembled copper ore. However, when miners were unable to extract any copper from it they blamed a mischievous sprite of German mythology, Nickel (similar to Old Nick) for besetting the copper. They called this ore Kupfernickel from the German Kupfer for copper.This ore is now known to be nickeline or niccolite, a nickel arsenide. In 1751, Baron Axel Fredrik Cronstedt was attempting to extract copper from kupfernickel and obtained instead a white metal that he named after the spirit which had given its name to the mineral, nickel. In modern German, Kupfernickel or Kupfer-Nickel designates the alloy cupronickel.

After its discovery the only source for nickel was the rare Kupfernickel, but from 1824 on the nickel was obtained as byproduct of cobalt blue production. The first large scale producer of nickel was Norway, which exploited nickel rich pyrrhotite from 1848 on. The introduction of nickel in steel production in 1889 increased the demand for nickel and the nickel deposits of New Caledonia, which were discovered in 1865, provided most of the world's supply between 1875 and 1915. The discovery of the large deposits in the Sudbury Basin, Canada in 1883, in Norilsk-Talnakh, Russia in 1920 and in the Merensky Reef, South Africa in 1924 made large-scale production of nickel possible.

Dutch coins made out of pure nickelNickel has been a component of coins since the mid 19th century. In the United States, the term "nickel" or "nick" was originally applied to the copper-nickel Flying Eagle cent which replaced copper with 12% nickel 1857-58, then the Indian Head cent of the same alloy from 1859-1864. Still later in 1865, the term designated the three-cent nickel, with nickel increased to 25%. In 1866, the five-cent shield nickel (25% nickel, 75% copper) appropriated the designation. Along with the alloy proportion, this term has been used to the present in the United States. Coins of nearly pure nickel were first used in 1881 in Switzerland, and more notably 99.9% nickel five-cent coins were struck in Canada (the world's largest nickel producer at the time) during non-war years from 1922–1981, and their metal content made these coins magnetic. During the wartime period 1942–45, more or all nickel was removed from Canadian and U.S. coins, due to nickel's war-critical use in armor. Canada switched alloys again to plated steel during the Korean war, but was forced to stop making pure nickel "nickels" in 1981, reserving the pure 99.9% nickel alloy after 1968 only to its higher-value coins. Finally, in the 21st century, with rising nickel prices, most countries that formerly used nickel in their coins have abandoned the metal for cost reasons, and the U.S. five-cent coin remains one of the few in which the metal is still used, save for exterior plating.

Metallurgy
Nickel is recovered through extractive metallurgy. Most sulfide ores have traditionally been processed using pyrometallurgical techniques to produce a matte for further refining. Recent advances in hydrometallurgy have resulted in recent nickel processing operations being developed using these processes. Most sulfide deposits have traditionally been processed by concentration through a froth flotation process followed by pyrometallurgical extraction.

Nickel is extracted from its ores by conventional roasting and reduction processes which yield a metal of greater than 75% purity. Final purification of nickel oxides is performed via the Mond process, which increases the nickel concentrate to greater than 99.99% purity. This process was patented by L. Mond and has been in use in South Wales since the 20th century. Nickel is reacted with carbon monoxide at around 50 °C to form volatile nickel carbonyl. Any impurities remain solid while the nickel carbonyl gas passes into a large chamber at high temperatures in which tens of thousands of nickel spheres, called pellets, are constantly stirred. The nickel carbonyl decomposes, depositing pure nickel onto the nickel spheres. Alternatively, the nickel carbonyl may be decomposed in a smaller chamber at 230 °C to create fine nickel powder. The resultant carbon monoxide is re-circulated through the process. The highly pure nickel produced by this process is known as carbonyl nickel. A second common form of refining involves the leaching of the metal matte followed by the electro-winning of the nickel from solution by plating it onto a cathode. In many stainless steel applications, 75% pure nickel can be used without further purification depending on the composition of the impurities.

Nickel sulfide ores undergo flotation (differential flotation if Ni/Fe ratio is too low) and then are smelted. After producing the nickel matte, further processing is done via the Sherritt-Gordon process. First copper is removed by adding hydrogen sulfide, leaving a concentrate of only cobalt and nickel. Solvent extraction then efficiently separates the cobalt and nickel, with the final nickel concentration greater than 99%.

Toxicity
Exposure to nickel metal and soluble compounds should not exceed 0.05 mg/cm³ in nickel equivalents per 40-hour work week. Nickel sulfide fume and dust is believed to be carcinogenic, and various other nickel compounds may be as well. Nickel carbonyl, [Ni(CO)4], is an extremely toxic gas. The toxicity of metal carbonyls is a function of both the toxicity of the metal as well as the carbonyl's ability to give off highly toxic carbon monoxide gas, and this one is no exception; nickel carbonyl is also explosive in air.Sensitized individuals may show an allergy to nickel affecting their skin, also known as dermatitis. Sensitivity to nickel may also be present in patients with pompholyx. Nickel is an important cause of contact allergy, partly due to its use in jewellery intended for pierced ears. Nickel allergies affecting pierced ears are often marked by itchy, red skin. Many earrings are now made nickel-free due to this problem. The amount of nickel which is allowed in products which come into contact with human skin is regulated by the European Union. In 2002 researchers found amounts of nickel being emitted by 1 and 2 Euro coins far in excess of those standards. This is believed to be due to a galvanic reaction.

It was voted Allergen of the Year in 2008 by the American Contact Dermatitis Society.

Reports also showed that both the nickel-induced activation of hypoxia-inducible factor (HIF-1) and the up regulation of hypoxia-inducible genes are due to depleted intracellular ascorbate levels. The addition of ascorbate to the culture medium increased the intracellular ascorbate level and reversed both the metal-induced stabilization of HIF-1 and HIF-1α dependent gene expression.

Cleaning

 * Mechanical

1.Abrasive particles or steel wool and water or oil mixture

2.Microsandblasting unit

3.Dry ice (CO2) blasting unit


 * Chemical

1.Diluted sulphuric acid

100 mll H2SO4

1 lit distilled water

Immerse object in solution,when it is clean rinse well, first with 5% baking soda solution,then with water.

2.Ethanol/sulphuric acid

2 mll H2SO4

98 mll ethanol

Immerse objects in solution(2-3 seconds!).Rinse well, first with 2% baking soda solution,then with water.

3.Sodium gluconate/citric & tartaric acid

47,5 gm sodium gluconate

47,5 gm citric acid

5 gm tartaric acid

1 lit water

Immerse object in solution(80 C temp.),when it is clean rinse well.


 * Electrochemical

50 gms sodium hydroxide

1 lit water

anode = Stainless steel,up to 12 v,1 A/dm2.


 * Ultrasonic


 * Laser

Clearcoats

 * Paraloid B 72
 * Paraloid B 67
 * Paraloid B 44
 * Paraloid B 48 N

Waxes

 * Renaissance Wax
 * Cosmolloid 80 H

Combinations

 * basecoat Paraloid B 72 + topcoat Renaissance Wax etc.