Copper purifying

Why does the electrolytic refining of copper purify it from gold From iron ... 

Cholestenone. Place a mixture of 1 0 g. of purified cholesterol and 0-2 g. of cupric oxide in a test-tube clamped securely at the top, add a fragment of Dry Ice in order to displace the air by carbon dioxide, and insert a plug of cotton wool in the mouth of the tube. Heat in a metal bath at 300-315° for 15 minutes and allow to cool rotate the test-tube occasionally in order to spread the melt on the sides. Warm with a few ml. of benzene and pour the black suspension directly into the top of a previously prepared chromatographic column (1) rinse the test-tube with a little more benzene and pour the rinsings into the column. With the aid of shght suction (> 3-4 cm. of mercury), draw the solution into the alumina column stir the top 0 -5 cm. or so with a stout copper wire to... 

Molybdenum is also recovered as a by-product of copper and tungsten mining operations. The metal is prepared from the powder made by the hydrogen reduction of purified molybdic trioxide or ammonium molybdate. 

The process operated by ACl is outlined in Figure 7. Bales of cotton linter are opened, cooked in dilute caustic soda, and bleached with sodium hypochlorite. The resulting highly purified ceUulose is mixed with pre-precipitated basic copper sulfate in the dissolver, and 24—28% ammonium hydroxide cooled to below 20°C is added. The mixture is agitated until dissolution is complete. If necessary, air is introduced to aUow oxidative depolymerization and hence a lowering of the dope viscosity. 

GaUic acid is heated with about half its weight of water in a copper autoclave until the pressure reaches 1.2 MPa (12 atm) and the temperature is 175°C. Steam and carbon dioxide are released but sufficient water is retained to maintain the pyrogaHol as a Hquid. The cooled solution is decolorized with animal charcoal and is then evaporated until the volatile pyrogaHol distills into iron receivers. The sohdified material is purified by repeated distillation, sublimation, or vacuum distillation at 200°C in the presence of diaLkyl phthalates (8). 

The extraction of metal ions depends on the chelating ability of 8-hydroxyquinoline. Modification of the stmcture can improve its properties, eg, higher solubility in organic solvents (91). The extraction of nickel, cobalt, copper, and zinc from acid sulfates has been accompHshed using 8-hydroxyquinohne in an immiscible solvent (92). In the presence of oximes, halo-substituted 8-hydroxyquinolines have been used to recover copper and zinc from aqueous solutions (93). Dilute solutions of heavy metals such as mercury, ca dmium, copper, lead, and zinc can be purified using quinoline-8-carboxyhc acid adsorbed on various substrates (94). 

Condensate Polishing. Ion exchange can be used to purify or poHsh returned condensate, removing corrosion products that could cause harmful deposits in boilers. Typically, the contaminants in the condensate system are particulate iron and copper. Low levels of other contaminants may enter the system through condenser and pump seal leaks or carryover of boiler water into the steam. Condensate poHshers filter out the particulates and remove soluble contaminants by ion exchange. 

The washed slime is dried and melted to produce slag and metal. The slag is usually purified by selective reduction and smelted to produce antimonial lead. The metal is treated ia the molten state by selective oxidation for the removal of arsenic, antimony, and some of the lead. It is then transferred to a cupel furnace, where the oxidation is continued until only the silver—gold alloy (dorn) remains. The bismuth-rich cupel slags are cmshed, mixed with a small amount of sulfur, and reduced with carbon to a copper matte and impure bismuth metal the latter is transferred to the bismuth refining plant. 

Electrowinning. Vat leaching often yields copper solutions having concentrations sufficiently high for direct electrowinning. However, high concentrations of cations other than copper and low copper concentrations make it more difficult to obtain high purity electrolytic copper by direct electrolysis of leach solutions than by electrolysis of purified solutions obtained from solvent extraction. 

This complex should be used when the organolithium is in solution in a hydrocarbon solvent. For organolithium reagents prepared in ether (see Note 4), the same complex may be used or, more conveniently, copper iodide (Cull can be used. The Cul purchased from Prolabo or Merck 4 Company, Inc. may be used directly. Other commercial sources of Cul (Fluka, Aldrich Chemical Company, Inc., Alfa Products, Morton/Thiokol, Inc.) furnish a salt which affords better results when purified. 1 mol of Cul is stirred for 12 hr with 500 ml of anhydrous tetrahydrofuran, then filtered on a sintered glass funnel ( 3), washed twice with 50 ml of anhydrous tetrahydrofuran, once with 50 ml of anhydrous ether and finally dried under reduced pressure (0.1 imO for 4 hr. 

Acrylic acid [79-10-7] M 72.1, m 13°, b 30°/3mm, d 1.051, pK 4.25. Can be purified by steam distn, or vacuum distn through a column packed with copper gauze to inhibit polymerisation. (This treatment also removes inhibitors such as methylene blue that may be present.) Azeotropic distn of the water with benzene converts aqueous acrylic acid to the anhydrous material. 

Hexafluoroetbane [76-16-4] M 138.0, b -79°. Purified for pyrolysis studies by passage through a copper vessel containing C0F3 at ca 270°, and held for 3h in a bottle with a heated (1300°) platinum wire. It was then fractionally distd. [Steunenberg and Cady J Am Chem Soc 74 4165 1962.]... 

Hydroxyquinoline (oxine, 8-quinolinol) [148-24-3] M 145.2, m 71-73 , 75-76 , 76 , b 267 pKj 4.91, pK 9.81. Crystd from hot EtOH, acetone, pet ether (b 60-80 ) or water. Crude oxine can be purified by pptn of copper oxinate, followed by liberation of free oxine with H2S or by steam distn after acidification with H2SO4. Stored in the dark. Forms metal complexes. [Manske et al. Can J Research 27F 359 1949 Phillips Chem Rev 56 271 1956.]... 

MeOH (copper-coloured prisms) or from diethyl ether by adding MeOH. Also purified by chromatography on columns of magnesia or calcium hydroxide, and crystd from CS2/EtOH. May be purified via the dipalmitate ester. Stored in the dark, in an inert atmosphere. 

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