Extraction, commercial processes extractions

Separation of Aromatic and Aliphatic Hydrocarbons. Aromatics extraction for aromatics production, treatment of jet fuel kerosene, and enrichment of gasoline fractions is one of the most important appHcations of solvent extraction. The various commercial processes are summarized in Table 4. 

Nitric acid acidulation of phosphate rock produces phosphoric acid, together with dissolved calcium nitrate. Separation of the phosphoric acid for use as an intermediate in other fertilizer processes has not been developed commercially. Solvent extraction is less effective in the phosphoric—nitric system than in the phosphoric—hydrochloric system. Instead, the nitric acid acidulate is processed to produce nitrophosphate fertilizers. 

Fig. 3. (a) Flame ionization detector (fid) response to an extract of commercially processed Valencia orange juice, (b) Gas chromatography—olfactometry (geo) chromatogram of the same extract. The abscissa in both chromatograms is a normal paraffin retention index scale ranging between hexane and octadecane (Kovats index). Dilution value in the geo is the -fold that the extract had to be diluted until odor was no longer detectable at each index. 

A commercial process which uses hydrothermal leaching on a large scale is the Bayer process for production of aluminum oxide (see Aluminum compounds). This process is used to extract and precipitate high grade alurninum hydroxide (gibbsite [14762-49-3]) from bauxite [1318-16-7] ore. The hydrothermal process step is the extraction step in which concentrated sodium hydroxide is used to form a soluble sodium aluminate complex ... 

Ma.nufa.cture. Nickel carbonyl can be prepared by the direct combination of carbon monoxide and metallic nickel (77). The presence of sulfur, the surface area, and the surface activity of the nickel affect the formation of nickel carbonyl (78). The thermodynamics of formation and reaction are documented (79). Two commercial processes are used for large-scale production (80). An atmospheric method, whereby carbon monoxide is passed over nickel sulfide and freshly reduced nickel metal, is used in the United Kingdom to produce pure nickel carbonyl (81). The second method, used in Canada, involves high pressure CO in the formation of iron and nickel carbonyls the two are separated by distillation (81). Very high pressure CO is required for the formation of cobalt carbonyl and a method has been described where the mixed carbonyls are scmbbed with ammonia or an amine and the cobalt is extracted as the ammine carbonyl (82). A discontinued commercial process in the United States involved the reaction of carbon monoxide with nickel sulfate solution. 

Solvent Extraction Reagents. Solvent extraction is a solution purification process that is used extensively in the metallurgical and chemical industries. Both inorganic (34,35) and organic (36) solutes are recovered. The large commercial uses of phosphine derivatives in this area involve the separation of cobalt [7440-48-4] from nickel [7440-02-0] and the recovery of acetic acid [61-19-7] and uranium [7440-61-1]. 

The odd-carbon stmcture and the extent of branching provide amyl alcohols with unique physical and solubiUty properties and often offer ideal properties for solvent, surfactant, extraction, gasoline additive, and fragrance appHcations. Amyl alcohols have been produced by various commercial processes ia past years. Today the most important iadustrial process is low pressure rhodium-cataly2ed hydroformylation (oxo process) of butenes. 

Additional commercial processes are available for extraction of tea, hops, oriental herbs, tobacco leaves, and pharmaceuticals C02-enhanced oil recovery environmental appHcations such as extraction/flocculation of aqueous wastes reactions with iategrated separations such as aminations (ethylene... 

Separation and Purification. Separation and purification of butadiene from other components is dominated commercially by the extractive distillation process. The most commonly used solvents are acetonitrile and dimethylformarnide. Dimethylacetamide, furfural, and... 

There is Httie recent information on the Exxon and BASE processes (85—87). The CRE, Exxon, and BASE processes use sulfuric acid as the extraction medium. The BASE process is the dominant process in Europe. It uses the dHutest acid of any commercial process. This permits selective reaction even in the presence of butadiene. The BASE process uses vapor—Hquid extraction unlike the Exxon and CRE processes which are of the Hquid—Hquid type. 

A typical feed to a commercial process is a refinery stream or a steam cracker B—B stream (a stream from which butadiene has been removed by extraction and isobutylene by chemical reaction). The B—B stream is a mixture of 1-butene, 2-butene, butane, and isobutane. This feed is extracted with 75—85% sulfuric acid at 35—50°C to yield butyl hydrogen sulfate. This ester is diluted with water and stripped with steam to yield the alcohol. Both 1-butene and 2-butene give j -butyl alcohol. The sulfuric acid is generally concentrated and recycled (109) (see Butyl alcohols). 

AH commercial processes for the manufacture of caprolactam ate based on either toluene or benzene, each of which occurs in refinery BTX-extract streams (see BTX processing). Alkylation of benzene with propylene yields cumene (qv), which is a source of phenol and acetone ca 10% of U.S. phenol is converted to caprolactam. Purified benzene can be hydrogenated over platinum catalyst to cyclohexane nearly aH of the latter is used in the manufacture of nylon-6 and nylon-6,6 chemical intermediates. A block diagram of the five main process routes to caprolactam from basic taw materials, eg, hydrogen (which is usuaHy prepared from natural gas) and sulfur, is given in Eigute 2. 

The crosscurrent scheme is not generally economically attractive for large commercial processes because solvent usage is high and solute concentration in the combined extract is low. 

Plant cell suspensions offer the potential to produce valuable phytochemicals, traditionally extracted from the naturally grown whole plant, under controlled and reproducible conditions. To date, commercial processes involving these systems have been limited to just a handful of applications, including the much-cited shikonin [1] and ginseng [2,3]. 

Computer programs are available for the design of extraction processes and would normally be included in the various commercial process simulation packages available see Chapter 4. 

METEX [Metal extraction] A process for extracting heavy metals from industrial waste waters by adsorption on activated sludge under anaerobic conditions. It is operated in an up-flow, cylindrical reactor with a conical separation zone at the top. Developed by Linde, originally for removing dissolved copper from winemaking wastes. First commercialized in 1987. 

Solvex [Solvent extraction] A process for extracting platinum metals from their ores by solvent extraction. Invented by Jonson Mathey in 1980 and piloted by that company, together with Rustenburg Platinum Holdings, since 1983. Commercialized in South Africa in the late 1980s. 

Zincex [Zinc extraction] A process for extracting zinc from pyrite cinder leachate, using organic solvents. The chloride leachate is first extracted with a secondary amine, and then with di(2-ethylhexyl)phosphoric acid to remove iron Developed by Tecnicas Reunidas, first commercialized in 1976, and now used in Spain and Portugal. 

Solvent extraction of benzene works the same way. But instead of water, the various solvents used are sulfolane, liquid SO2, diethylene-glycol, and NMP (N-methyl pyrrolidone). The paint thinner/salt/water process described above might be called a batch solvent process, since it consists of sequential steps that can be repeated, batch after batch. Some low-volume commercial processes still operate that way. 

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