Industrial applications metal extraction

In view of industrial applications, after extraction from water, the metallic cation has to be transferred from the organic extraction phase into a fresh aqueous phase (possibly acidified, to avoid precipitation) from which various hydrometallurgical processes can be easily implemented. This operation is called either back-extraction or stripping. This is of course an important industrial aspect which is nevertheless often neglected in academic studies, assuming reversibility of processes. 

Other industrial applications of electrolysis include extraction/purification of metals from ores, electroplating, and the manufacture of certain chemicals such as sodium hydroxide. In the latter, sodium chloride solution when electrolysed is converted to sodium hydroxide to produce chlorine at the anode and hydrogen at the cathode. Both of these gaseous by-products are collected for industrial use chlorine is used in the production of bleach and PVC hydrogen is used as a fuel, to saturate fats, and to make ammonia. 

We have already described the refining of copper and the electrolytic extraction of aluminum, magnesium, and fluorine. Another important industrial application of electrolysis is the production of sodium metal by the Downs process, the electrolysis of molten rock salt (Fig. 12.15) ... 

Wisniewski, M. Szymanowski, J. Industrial applications of noble metals extraction. Pol. J. Appl. Chem. 1996, 40, 17-26. 

All negatively charged metal complexes can be extracted by liquid anion exchangers, independent of the nature of the metal and the complexing ligand. Liquid anion exchange has extensive industrial application, and many examples are given in later chapters. Lists of extraction values are found in other works [e.g., 5, 21]. 

Ketones are an important class of industrial chemicals that have found widespread use as solvents and chemical intermediates. Acetone (qv) is the simplest and most important ketone and finds ubiquitous use as a solvent. Higher members of the aliphatic methyl ketone series (eg, methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone) are also industrially significant solvents. Cyclohexanone is the most important cyclic ketone and is primarily used in the manufacture of y-caprolactam for nylon-6 (see Cyclohexanoland cyclohexanone). Other ketones find application in fields as diverse as fragrance formulation and metals extraction. Although the industrially important ketones are reviewed herein, the laboratory preparation of ketones is covered elsewhere (1). 

The ion exchange resin selected for this study was a copolymer of styrene with divinylben ne with a weakly basic iminodiacetic function group. The reason for this choice is that it has been studied in the extraction of transition metal and other ions (8-10), is commercially available, and is being used in industrial applications. At first it would appear that the prevalent complexation of iminodiacetic acid with most metallic elements would preclude the type of selectivity sought for the Sc extraction. But such separations are possible by the exploitation of specific chemical behavior and complexation characteristics. 

Baitsch RA, Chun S, Dzyuba SV (2002) Ionic liquids as novel dUuenfs for solvenf extraction of metal salts by crown ethers. In Rogers RD, Seddon KR (eds) Ionic liquids industrial applications for green chemistry. American Chemical Society, Washington, DC... 

It is used in the mining industry to recover metals such as copper and nickel. Parasite plants, based on solvent extraction, are used in the phosphate industry to recover by-product uranium from crude phosphoric acid. The uranium concentration in phosphoric acid is very low but, because of the high volume of phosphoric acid that is produced to meet agricultural needs, considerable uranium can be recovered using solvent extraction. In the nuclear industry [5], solvent extraction is used to purify uranium and plutonium [using the plutonium and uranium recovery by extraction (PUREX) process], zirconium from hafnium, and for many other applications. It is also used in environmental applications to clean soil, say, to remove polychlorinated biphenyls (PCBs), dioxins, pesticides, and other hazardous pollutants. 

Aromatic nitriles can be thermally selectively polymerized in pyrrolidin-2-one at temperatures above 200 C. Between 200 and 350 °C trimerization to 2,4,6-triaryl-l,3,5-triazines occurs, while at temperatures above 300 °C imidization occurs resulting in nonmelting, linear polyaryl-carbimine. Mixtures of trimers and polymeric imines are separable by sublimation or extraction with aromatic hydrocarbons.180 Since aryltriazines and polymeric aryltriazines have various industrial applications, several catalytic systems have been developed for the trimerization of aromatic nitriles and dinitriles, e.g. metal chlorides,181 iron(II) or iron(lll) cyanide,182 cop-per(II) carbonate,183 and molten zinc(II) chloride.184... 

The physical and chemical principles governing the formation of extractable metal complexes, the conclusions which can be drawn about the chemical system from solvent extraction studies, and analytical and industrial applications are described in several monographs, e.g. "Principles and Practices of Solvent Extraction" (1992). 

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