Copper refinement

Current density can be increased without impairing the quaUty of the copper by polishing the cathode surface by brief periodic current reversals (PCR). Reversed current electrolysis, first developed for electroplating, was tested in 1952 for copper refining. Although good results were obtained, no suitable electrical equipment for current reversal was available. The thyristor-controUed siUcon rectifier, introduced in the 1960s, provided a means for... 

Iron selenide can be obtained from the Canadian Copper Refiners Ltd., Montreal, Quebec. 

Kupfer-pol, m. Elec.) copper pole (positive pole), -praparat, n. copper preparation, -probe,/, copper assay, test for copper, -raf-fination, /. copper refining, -ranch, m. copper smoke, copper fumes white vitriol,... 

Rosetten-baim, /. roset(te) orbit or path, -herd, m. (Copper) refining hearth, -kupfer,... 

The platinum metals are valuable by-products from the extraction of common metals such as copper and nickel. The anodic residue that results from copper refining is a particularly important source. The chemistry involved in their purification is too complicated to describe here, except to note that the final reduction step involves reaction of molecular hydrogen with metal halide complexes. 

Electrolytic copper refining Blister copper Process wastewater Slimes containing impurities such as gold, silver, antimony, arsenic, bismuth, iron, lead, nickel, selenium, sulfur, and zinc... 

Copper sulfate can be described as a by-product of copper refining that is obtained by crystallization of the weak liquor. The copper sulfate precipitate formed is centrifuged, dried, screened, and finally packaged in bags and drum. However, it is produced in some chemical industries by reacting copper shot with sulfuric acid, air, and water. It is widely used as an insecticide, additive nutrients (for soils that are deficient in copper), copper electroplating, wood preservation, and in petroleum refining. 

This value is based on Cu2+ diffusivities calculated Arvia et al. (A5) from limiting-current measurements at a rotating-disk electrode by, with CuS04 concentrations below 0.1 M. In practical applications (e.g., copper refining or electrowinning) higher Cu2+ concentrations are often required, as is also the case in free-convection limiting-current measurements. 

The unsoftened lead obtained after the softening operation contains silver in small but significant quantities. Such unsoftened lead is cast into anode and subjected to electrolytic refining. The anode mud that is formed adhering to these anodes is removed by scraping. It contains bismuth, silver, gold, and other impurity metals. Silver is obtained from this anode mud by methods similar to the extraction of anode mud from the copper refining process discussed earher. 

Tellurium dioxide in its orthorhombic form occurs in nature as mineral tellurite. It is mined from natural deposits. Also, tellurium dioxide is produced as an intermediate during recovery of tellurium metal from anode shmes of electrolytic copper refining (See Tellurium, Production). The dioxide also is prepared by treating tellurium metal with hot nitric acid to form 2Te02 HNO3. The product then is heated to drive off nitric acid. 

Sixty per cent of the palladium manufactured worldwide - mainly as a by-product of nickel, zinc, and copper refining - is now used in catalytic converters. Much of the rest is used in electronic components, but a little is used for jewellery, showing that we have after all acquired a taste for Wollaston s untarnishable silver . 

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