Extraction and Refining

Acetonitrile also is used as a catalyst and as an ingredient in transition-metal complex catalysts (35,36). There are many uses for it in the photographic industry and for the extraction and refining of copper and by-product ammonium sulfate (37—39). It also is used for dyeing textiles and in coating compositions (40,41). It is an effective stabilizer for chlorinated solvents, particularly in the presence of aluminum, and it has some appflcation in... 

C. Bodsworth, The Extraction and Refining of Metals CRC Press, Inc., Boca Raton, El., 1994. 

B. R. Steele and D. Geldait, "Extraction and Refining of the Raiei Metals," Proceedings of the Symposium on the Institute ofMiningand Metallurgy,... 

Cast-iron column shells are satisfactory, but stainless-steel bubble or valve trays are preferred. A flow sheet of a typical tar acid extraction and refining plant is shown in Figure 3. 

Carbon monoxide Chlorinated hydrocarbons G Coke ovens Incomplete combustion generally Smelting Vehicle exhausts Metal extraction and refining... 

Liquid fuels for use in internal-combustion engines are extracted and refined from crude oil, with diesel fuels being part of the middle distillate or kerosene fraction. Kerosene was initially derived from coal pyrolysis. The initial main use of this type of distillate was for the kerosene lamp, which had replaced lamps based on whale oil. 

Plants handling aqua regia Aqua regia is used extensively in the extraction and refining of the precious metals, and tantalum, as one of the few metals resistant to this medium, is used for dissolution/evaporation pans, reactor lids and all immersed ancillary equipment. 

Sulphur oxides G Sulphur dioxide Metal extraction and refining Coal distillation... 

Ore obtained from a mining operation contains a desired minerai contaminated with other components, which may inciude sand, ciay, and organic matter. This economicaiiy vaiueiess portion of the ore, which is caiied gangue (pronounced gang ), must be removed before the metai can be extracted and refined. Ores can be separated into components by physicai or chemicai methods. 

T. K. Mukherjee and C. K. Gupta, Fused Salt Electrolysis for Refractory Metal Extraction and Refining, Trans SAEST, Vol. 11, No. 1, p. 127,1976. 

When nonrenewable mineral resources are processed for metal extraction and the metals extracted are utilized in various ways and in diverse forms, they become potentially available for reclamation and recycling. Recycled metals produced by the extraction and refining of metallic wastes are known as secondary metals, whereas metals produced from primary ores are termed primary metals. A classification of recyclable metalliferous resources such... 

Bryant, P. S., in Extraction and Refining of the Rarer Metals, The Institute of Mining and Metallurgy, London, 1957, 310. 

Airborne particulate matter may be associated with many carcinogenic and other toxic agents. Hazardous materials include coal dust, fly-ash from power stations, metals and metal oxides from mining, extraction and refining and materials used as catalysts in industrial processes, as well as particulate matter from, for example, diesel exhausts. 

In this section, you iearned how stoichiometry reiates the quantities of reactants and products to the quantity of eiectricity consumed in an eiectroiytic ceii. You used Faraday s iaw to soive prohiems reiating to eiectroiysis. You aiso iearned that the extraction and refining of some metais are carried out eiectroiyticaiiy. In the next section, you will see several other important applications of electrochemistry to modern society. 

Describe some electrolytic processes involved in extracting and refining metals. 

Stahl, E. Quirin, K.-W. Gerard, D. Dense Gases for Extraction and Refining, Springer-Verlag Berlin, 1987. 

There are several processes for extracting and refining niobium from its ores. (Payton, P.H. 1981. Niobium and Niobium Compounds. In Kirk-Othmer Encyclopedia of Chemical Technology, 3 . ed., Vol, 15, pp. 820-827. New York Wiley Interscience). The process of choice depends on nature of the ore and end use intended for the metal. Some common steps in these recovery processes involve ore preconcentration, breaking or opening the ore, obtaining pure niobium compounds, reduction of niobium compounds to niobium metal, purification or refining metal and fabrication. If niobium is extracted from a niobium-tantalum ore, the most important step is separation of niobium from tantalum, both of which are chemically very similar. 

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