Minerals nickel oxide

Little is known concerning the chemistry of nickel in the atmosphere. The probable species present in the atmosphere include soil minerals, nickel oxide, and nickel sulfate (Schmidt and Andren 1980). In aerobic waters at environmental pHs, the predominant form of nickel is the hexahydrate Ni(H20)g ion (Richter and Theis 1980). Complexes with naturally occurring anions, such as OH, SO/, and Cf, are formed to a small degree. Complexes with hydroxyl radicals are more stable than those with sulfate, which in turn are more stable than those with chloride. Ni(OH)2° becomes the dominant species above pH 9.5. In anaerobic systems, nickel sulfide forms if sulfur is present, and this limits the solubility of nickel. In soil, the most important sinks for nickel, other than soil minerals, are amorphous oxides of iron and manganese. The mobility of nickel in soil is site specific pH is the primary factor affecting leachability. Mobility increases at low pH. At one well-studied site, the sulfate concentration and the... 

The matte can be treated in different ways, depending on the copper content and on the desired product. In some cases, the copper content of the Bessemer matte is low enough to allow the material to be cast directly into sulfide anodes for electrolytic refining. Usually it is necessary first to separate the nickel and copper sulfides. The copper—nickel matte is cooled slowly for ca 4 d to faciUtate grain growth of mineral crystals of copper sulfide, nickel—sulfide, and a nickel—copper alloy. This matte is pulverized, the nickel and copper sulfides isolated by flotation, and the alloy extracted magnetically and refined electrolyticaHy. The nickel sulfide is cast into anodes for electrolysis or, more commonly, is roasted to nickel oxide and further reduced to metal for refining by electrolysis or by the carbonyl method. Alternatively, the nickel sulfide may be roasted to provide a nickel oxide sinter that is suitable for direct use by the steel industry. 

Other Specialty Chemicals. In fuel-ceU technology, nickel oxide cathodes have been demonstrated for the conversion of synthesis gas and the generation of electricity (199) (see Fuel cells). Nickel salts have been proposed as additions to water-flood tertiary cmde-oil recovery systems (see Petroleum, ENHANCED oil recovery). The salt forms nickel sulfide, which is an oxidation catalyst for H2S, and provides corrosion protection for downweU equipment. Sulfur-containing nickel complexes have been used to limit the oxidative deterioration of solvent-refined mineral oils (200). 

More than 90% of the world s nickel is obtained from pentlandite ((FeNi)9S8), a nickel-sulfitic mineral, mined underground in Canada and the former Soviet Union (Sevin 1980 IARC 1976 WHO 1991). One of the largest sulfitic nickel deposits is in Sudbury, Ontario (USPHS 1993). Nickeliferous sulfide deposits are also found in Manitoba, South Africa, the former Soviet Union, Finland, western Australia, and Minnesota (Norseth and Piscator 1979 USPHS 1993). Most of the rest of the nickel obtained is from nickel minerals such as laterite, a nickel oxide ore mined by open pit techniques in Australia, Cuba, Indonesia, New Caledonia, and the former Soviet Union (Sevin 1980). Lateritic ores are less well defined than sulfitic ores, although the nickel content (1 to 3%) of both ores is similar (USPHS 1993). Important deposits of laterite are located in New Caledonia, Indonesia, Guatemala, the Dominican Republic, the Philippines, Brazil, and especially Cuba, which holds 35% of the known reserves (USPHS 1993). Nickel-rich nodules are found on the ocean floor, and nickel is also present in fossil fuels (Sevin 1980). 

Nickel oxide (NiO) is produced from nickel minerals to form nickel oxide when heated to 400°C, which is then reduced at a temperature of 600°C, resulting in the formation of nickel oxide. It is used as electrodes in fuel cells. 

Nickel is a silver-white, lustrous, hard, malleable, ductile, ferromagnetic metal that is relatively resistant to corrosion and is a fair conductor of heat and electricity. Nickel is a ubiquitous trace metal that occurs in soil, water, air, and in the biosphere. The average content in the earth s crust is about 0.008%. Nickel ore deposits are accumulations of nickel sulfide minerals (mostly pentlandite) and laterites. Nickel exists in five major forms elemental nickel and its alloys inorganic, water-soluble compounds (e.g., nickel chloride, nickel sulfate, and nickel nitrate) inorganic, water-insoluble compounds (e.g., nickel carbonate, nickel sulfide, and nickel oxide) organic, water-insoluble compounds and nickel carbonyl Ni(CO). ... 

Huebner I S. and Sato M. (1970). The oxygen fugacity-temperature relationships of manganese oxide and nickel oxide buffers. Amer. Mineral, 55 934-952. 

Several nickel salts are obtained by reactions of nickel oxide with mineral acids. Thus, the reaction of black nickel oxide with hot dilute sulfuric acid forms nickel sulfate, NiS04 6H2O. Similarly, dilute nitric acid, hydrochloric, and hydrobromic acids when heated react with the black form of nickel oxide to yield corresponding nickel salts as hexahydrates. 

Supported nickel catalysts catalyze steam-methane reforming and the concurrent shift reaction. The catalyst contains 15-25 wt% nickel oxide on a mineral carrier. Carrier materials are alumina, aluminosilicates, cement, and magnesia. Before start-up, nickel oxide must be reduced to metallic nickel with hydrogen but also with natural gas or even with the feed gas itself. 

The catalyzed complete combustion of individual hydrocarbons has been investigated by Todes in an attempt to establish the combustion characteristics of these hydrocarbons (220), while other workers have attempted to improve the techniques of catalyzed combustion (457). At the Power Institute Ravich has been working on the development of catalysts promoting complete combustion of gaseous and solid fuels with the aid of naturally occurring and synthetic minerals containing oxides of iron, chromium, nickel, potassium, aluminum, and manganese (317,-318,319). Industrial application of this process has been mentioned. 

A number of low-grade transition metal ores (for example, minerals containing nickel oxides) can be used as catalysts. Smuda has demonstrated that microwave or radiofrequency irradiation of a mixture of such ores with a carbon source initiates reduction of the oxide to metal. With this approach, poisoning the active sites of the catalyst will not be critical for the process since there will be a constant supply and generation of active catalyst with the feed material. In addition to well-known catalytic properties of nickel in organic reactions, it was also shown that Ni on carbon and other supports, catalyzes hydrodechlorination and dehydrochlorination of chlorinated organic waste streams [22-24],... 

Jim Skeaff and Pierrette King, Development of Data on the Reaction Kinetics of Nickel Metal and Nickel Oxide in Aqueous Media for Hazard Identification, Final Report, January 1998. Mining and Mineral Sciences Laboratories Division Report 97-089(CR)/Contract No. 51605... 

We tried to dissolve away the free nickel oxide with a dilute mineral acid and found that treatment with 2 N hydrochloric acid for 24 hours at room temperature was enough to dissolve away the free nickel oxide in the catalyst selectively, as shown in Fig. 3 (6). 

Scheckel. K. G., and Sparks, D. L. (2001). Dissolution kinetics of nickel surface precipitates on clay mineral and oxide surfaces. Soil Sci. Soc. Am. J. 65, 685-694. 

Pale yellow mass resembling silk. Insol in water, alcohol, ether, dil alkalies. Sol in coned alkalies, coned mineral acids and in ammoniacal nickel oxide soln. 

The success of the carbonaceous reduction of iron oxide has opened doors for the beneficiation of other minerals that coexist with oxides of iron also known as mineral sands. Examples of these ores are ilmenite, containing titanium dioxide and laterite ore, containing nickel oxide. Titanium dioxide (Ti02) is one of the most important inorganic materials used as a pigment for paper, plastics, paints, textile, and so on. 

The second most used material is nickel oxide which is processed from nickel ore and used for the anode substrate and anode together with yttrium-stabilized zirkonia in form of a cermet and as a nickel mesh for the anode contact layer. Yttrium-stabilized zirconia is produced from rare earths and mineral sands. 

Like cobalt, nickel occurs as sulfide and arsenide minerals, e.g. pentlandite, (Ni,Fe)9Sg. Roasting such ores in air gives nickel oxide which is then reduced to the metal using carbon. The metal is refined electrolytically or by conversion to Ni(CO)4 followed by thermal decomposition (eq. 21.4). This is the Mondprocess, which is based on the fact that Ni forms a carbonyl derivative more readily than any other metal. 

---