A Variety of Refining Processes

The high-grade matte from the converter process or the flash melting process contains sulfur and some amounts of copper, cobalt and iron and, in addition, traces of noble metals. Refined nickel is produced by a variety of methods and is delivered as nickel cathodes or nickel powder. The latter are produced partly by carbonyl processes, partly by hydrogen reduction in conjunction with pressure leaching processes. In the latter, matte is leached under pressure with acid or ammonia, and nickel is recovered as a powder by reduction with hydrogen under pressure. 

A special refining process is the carbonyl nickel process, an old process, which was invented in 1902 in Wales and used as the Langer-Mond process. Originally the plant treated nickel-copper matte but the process today is highly modified. The principle is a treatment at 60°C with carbon monoxide at atmospheric pressure. Nickel carbonyl, Ni(CO) is formed. This is a volatile Kquid that melts at -19.3°C and boils at 42.5°C. In this process nickel (and some iron) is carried off while other metals remain. Heating the gas to 180°C decomposes it and pure nickel powder is obtained. 

In a modern high-pressure variant the feed material is a special pretreated matte (with, for example, 77% Ni, 15% Cu, 4% (Coi-Fe) and 4% S). Granules of this matte are treated with CO at temperatures up to 180°C and a pressure of 7 MPa. The nickel carbonyl vapor is decomposed, often on nickel pellets. 

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Refined petroleum products are obtained from cmde oil through a variety of refining processes including ... 

Petroleum sulfonates have traditionally been produced by both batch and continuous treatment of petroleum oils with oleum. These processes have been covered in several reviews (138,139). Natural petroleum sulfonates are coproducts in the manufacture of a variety of refined oils, most notably white (mineral) oils, lube oils, and process oils (plasticizer oils for mbber compounding). The feedstocks are selected primarily on the basis of the desired characteristics of the refined oils which generally contain 15—30% aromatics. 

Metal surfaces have long been appreciated for their catalytic properties the ability to alter the pathways of important chemical reactions so as to increase reaction rates and selectivity for desired products well above the rates occurring in a homogeneous phase. Catalytic metals are widely utilized in a variety of chemical processes, and have been critical for processes that have had worldwide energy and health benefits, such as the petroleum refining process for fuel production, the Haber-Bosch... 

Production. Indium is recovered from fumes, dusts, slags, residues, and alloys from zinc or lead—zinc smelting. The source material itself, a reduction bullion, flue dust, or electrolytic slime intermediate, is leached with sulfuric or hydrochloric acid, the solutions are concentrated, if necessary, and cmde indium is recovered as 99+% metal. This impure indium is then refined to 99.99%, 99.999%, 99.9999%, or higher grades by a variety of classical chemical and electrochemical processes. 

Aromatic Isocyanates. A variety of methods are described in the Hterature for the synthesis of aromatic isocyanates. Only the phosgenation of amines or amine salts is used on a commercial scale (5). Much process refinement has occurred to minimise the formation of disubstituted ureas arising by the reaction of the generated isocyanate with the amine starting material. A listing of the key commercially available isocyanates is presented in Table 1. 

In the chemical engineering domain, neural nets have been appHed to a variety of problems. Examples include diagnosis (66,67), process modeling (68,69), process control (70,71), and data interpretation (72,73). Industrial appHcation areas include distillation column operation (74), fluidized-bed combustion (75), petroleum refining (76), and composites manufacture (77). 

Raw petroleum (crude oil) is extracted from underground around the globe in a variety of ways and refined for tens of thousands of applications in our everyday lives. Crude oil is refined into usable petroleum products through several unique processes. Fractional distillation is the process used to efficiently extract or "distill" products that are a mixture of chemicals such as gasoline, diesel fuel, and kerosene or may selectively extract pure chemical compounds or petrochemicals such as... 

Potential sources of carbon monoxide hazards include metal-refining processes, in which it is formed as a byproduct and used as a fuel (LEL 12.5%), and running vehicle engines (particularly petrol-driven) or gas-fired heaters in poorly ventilated confined spaces. It is also a feedstock in the manufacture of a variety of chemicals, e.g. methanol, acetic acid, phosgene and oxo-alcohols. 

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