Cement copper

Cement clinker Cement-composites Cement copper Cemented carbide... 

Hydrometallurigcal Processes. In hydrometaHurgical processes, metal values and by-products are recovered from aqueous solution by chemical or electrolytic processes. Values are solubilized by treating waste, ore, or concentrates. Leaching of copper ores in place by rain or natural streams and the subsequent recovery of copper from mnoff mine water as impure cement copper have been practiced since Roman times. Most hydrometaHurgical treatments have been appHed to ores or overburden in which the copper was present as oxide, mixed oxide—sulfide, or native copper. PyrometaHurgical and hydrometaHurgical processes are compared in Reference 34. 

Zement-kalk, m. hydraulic lime, -kalkmdrtel, m. lime-and-oement mortar, -kalkstein, m. hydraulic limestone, -kohle, /. cementation carbon, -kufe, -kiipe, /. cement (or concrete) vat. -kupfer, m. cement copper, -mastiz, m. mastic cement, -metoll, n. metal precipitated by the cementation process. -miUk, /. thin cetnent mortar. 

Cement copper, 7 688 Cemented carbides, 4 655-674, 693 25 359 economic aspects, 4 672 metal-cutting applications, 4 662-670 nonmetal-cutting applications,... 

Cementation is the process of recovery of metals from dilute aqueous solution by reductive precipitation using another metal with a more negative electrode potential, e.g., Cu + Fe° Cu° + Fe. The product, in this case cement copper, is relatively impure because of iron contamination. However, cementation can be used in conjunction with a solvent extraction flow sheet to remove small amounts of a metallic impurity, for example, removal of copper from a nickel solution by cementation with nickel powder. Here the dissolved nickel conveniently augments the nickel already in solution. 

Scrap iron - [PIGMENTS - INORGANIC] (Vol 19) -for copper cementation [COPPER] (Vol 7)... 

After lixiviation of the sulphate, oxide, or chlorides obtained by these methods, the copper is precipitated by the process already described. If the cement copper thus obtained contains over 55 per cent, of the metal, it is refined directly, if the percentage is lower, it is first smelted with matte or calcined copper pyrites. 

The replacement of the chlorine by hydroxyl takes place under the catalytic influence of copper oxide. Instead of the oxide, cement copper, or finely divided sheet copper, can be used equally well. 

Cementation involves precipitation of the copper by passage of the leach solution over scrap iron (Eq. 13.25). This requires about 1 hr of contact time and produces a finely divided form of the metal analyzing ca. 90% Cu (dry) by replacement of the dissolved copper by iron. In theory this should only require 0.879 kg of iron for each kilogram of copper obtained (Eq. 13.25). In practice there is an iron consumption of 1.3-3 kg/kg copper [44]. At times as much as 10% of U.S. production has been from cement copper. 

Unfortunately, the copper product requires extensive refining before being marketable. Moreover, scrap iron cannot displace zinc, cadmium, or many other trace contaminants from solution. Zinc is more versatile than scrap iron, having a lower reduction potential. However, although zinc is used extensively in hydrometallurgical processes to cement copper, nickel, and cobalt from zinc leach solutions before electrolysis " and to recover gold and silver in the Merrill-Crowe process. the Zn + ions introduced into solution would be unacceptable for environmental applications, even if the process were economically attractive. 

A continuous pilot plant test of the flowsheet (Figure 6) was established at SGS Minerals. The first four steps in the process, PLATSOL , PGM cementation, copper concentrate enrichment and copper precipitation were included in the continuous run. The copper depleted solution from copper precipitation was collected and a series of batch tests were used to complete the remaining flowsheet steps. The step by step results of the testing are summarized below. 

Applications. Sealing IC packages, cementing copper foil to printed wiring boards. 

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