Minerals chalcocite

Fig. 1. Effect of particle size on the flotation recovery of a sulfide mineral. Mineral chalcocite [2112-20-9J, CU2S reagent potassium ethyl xanthate,...

The compound occurs in nature as the mineral chalcocite (copper glance) with varying colors. 

Copper(l) sulfide is available in nature as the mineral chalcocite. It also may be made by heating copper(ll) sulfide with hydrogen, in the presence of small amounts of sulfur. 

Cuprous Sulfide, CUjS,mw 159 20, blk solid, mp ca 1100° occurs as the mineral chalcocite (copper glance). Can be prepd by heating CuS in a stream of hydrogen or by other methods (Refs 1, 2, 4 7). Used in protective paint for vessels (Ref 9, P 321... 

Sulfides. The simple or (less frequently) complex sulfides of a number of heavy metals are employed extensively as sources of these metals. For example, the minerals chalcocite (CU2S), chalcopyrite (CuFeS2), cinnabar (HgS),galena (PbS), and sphalerite (ZnS) are typical of the useful sulfide ores of heavy metals. 

Properties Black powder or lumps. D 5.52-5.82, mp approximately 1100C. Soluble in nitric acid and ammonium hydroxide insoluble in water. Occurs as the mineral chalcocite. 

Many desirable chemical reactions, including a large number that are central to hving systems, are nonspontaneous as written. For example, consider the extraction of copper metal from the mineral chalcocite, which contains CU2S. The decomposition of CU2S to its elements is nonspontaneous ... 

In this process, which has been proposed on the basis of laboratory scale studies, copper sulfide minerals, chalcocite, chalcopyrite, etc., are mixed with burned lime, pelletized, and then roasted at a temperature of about 500°C. The principal objective of the operation is to transform the copper... 

Copper ore minerals maybe classified as primary, secondary, oxidized, and native copper. Primaryrninerals were concentrated in ore bodies by hydrothermal processes secondary minerals formed when copper sulfide deposits exposed at the surface were leached by weathering and groundwater, and the copper reprecipitated near the water table (see Metallurgy, extractive). The important copper minerals are Hsted in Table 1. Of the sulfide ores, bornite, chalcopyrite, and tetrahedrite—teimantite are primary minerals and coveUite, chalcocite, and digenite are more commonly secondary minerals. The oxide minerals, such as chrysocoUa, malachite, and azurite, were formed by oxidation of surface sulfides. Native copper is usually found in the oxidized zone. However, the principal native copper deposits in Michigan are considered primary (5). 

Cuprous chalcogenides, CU2X, are basically dimorphic. The low-chalcocite CU2S (an important and widely distributed ore mineral of copper) has a structure... 

Main opaque minerals are chalcopyrite, pyrite, pyrrhotite, sphalerite and bornite (Table 2.22). These minerals commonly occur in massive, banded and disseminated ores and are usually metamorphosed. Hematite occurs in red chert which is composed of fine grained hematite and aluminosilicates (chlorite, stilpnomelane, amphibole, quartz) and carbonates. The massive sulfide ore bodies are overlain by a thin layer of red ferruginous rock in the Okuki (Watanabe et al., 1970). Minor opaque minerals are cobalt minerals (cobaltite, cobalt pentlandite, cobalt mackinawite, carrollite), tetrahedrite-tennantite, native gold, native silver, chalcocite, acanthite, hessite, silver-rich electrum, cubanite, valleriite , and mawsonite or stannoidite (Table 2.22). 

It is noteworthy that bornite, chalcocite and tetrahedrite-tennantite which are common minerals in Kuroko deposits occur in gold bearing Besshi-type deposits. Although these minerals are considered to be secondary minerals, depositional environments of these minerals are characterized by higher /s, and foj conditions. It is also noteworthy that these deposits are rich in pyrite rather than pyrrhotite. Probably, Besshi-subtype deposits in Shikoku formed under the higher fo and /sj conditions than the deposits characterized by pyrrhotite (Maizuru, Hidaka, Kii, east Sanbagawa). Such typical Besshi-type deposits (Besshi-subtype deposits in Shikoku) are characterized by simple sulfide mineral assemblage (chalcopyrite, pyrite, small amounts of sphalerite). Inclusion of bornite in pyrite is also common in these deposits. 

A single metal may be extracted from several minerals. Thus there are many minerals of copper, such as chalcocite, bornite, chalcopyrite, cuprite, native copper, and malachite one or more of these may occur in an individual deposit. Also, more than one metal may be obtained from a single mineral stannite, for example, yields both copper and tin. A mineral deposit, therefore, may yield several metals from different minerals. 

The adsorption of collectors on sulfide mineral occurs by two separate mechanisms chemical and electrochemical. The former results in the presence of chemisorbed metal xanthate (or other thiol collector ion) onto the mineral surface. The latter yields an oxidation product (dixanthogen if collector added is xanthate) that is the hydrophobic species adsorbed onto the mineral surface. The chemisorption mechanism is reported to occur with galena, chalcocite and sphalerite minerals, whereas electrochemical oxidation is reportedly the primary mechanism for pyrite, arsenopyrite, and pyrrhotite minerals. The mineral, chalcopyrite, is an example where both the mechanisms are known to be operative. Besides these mechanisms, the adsorption of collectors can be explained from the point of interfacial energies involved between air, mineral, and solution. 

The sulfuric acid needed to solubilize copper from chalcocite is balanced by the acid recovered from the copper electrowinning step this acid is recycled to the heaps. The overall acid requirements for the process are, therefore, dependent on the acid consumption by the gangue minerals in the ore and the acid production by pyrite oxidation. If the pyrite associated with the ore is significant and the acid consumption by the ore is low, excess sulfuric acid can be neutralized by lime. 

Mixed copper sulphide oxide ores. These contain varieties of both sulphide and oxide minerals, and are the most complex copper-bearing ores from a beneficiation point of view. The major copper minerals present in this ore type include bomite, chalcocite, covellite, malachite, cuprite and chrysocolla. In some cases, significant amounts of cobalt minerals are also present in this ore. 

Occurrence. Copper is a typical chalcophilic element its principal minerals are sulphides, mostly chalcopyrite (CuFeS2), bornite (CusFeSyCujFeSj) and chalcocite... 

Young et al. (in press) conducted related experiments. They examined the Cu isotope compositions of the solutions produced during acid sulfate leaching experiments aimed at extracting Cu from ore minerals (chalcopyrite, chalcocite, djurleite, bomite). The leaching experiment for chalcopyrite reads ... 

These authors observed that the leach solutions of chalcocite become more and more depleted in Cu and that this depletion is accompanied by a decrease of the Cu/S ratios of the solution from 2 to 1, which these authors ascribe to fractionation between diversely coordinated Cu in the different minerals. In contrast to chalcocite, chalcopyrite leaching produces no isotope fractionation. These authors also conclude from a comparison between columns seeded with bacteria and sterile columns that bacterial mediation had little if any influence on Cu isotopic fractionation in this specific experiment, which simply reflects that bacteria do not store signiflcant amounts of metal. 

Abstract In the beginning, the mixed potential model, which is generally used to explain the adsorption of collectors on the sulphide minerals, is illustrated. And the collector flotation of several kinds of minerals such as copper sulphide minerals, lead sulphide minerals, zinc sulphide minerals and iron sulphide minerals is discussed in the aspect of pulp potential and the nature of hydrophobic entity is concluded from the dependence of flotation on pulp potential. In the following section, the electrochemical phase diagrams for butyl xanthate/water system and chalcocite/oxygen/xanthate system are all demonstrated from which some useful information about the hydrophobic species are obtained. And some instrumental methods including UV analysis, FTIR analysis and XPS analysis can also be used to investigated sulphide mineral-thio-collector sytem. And some examples about that are listed in the last part of this chapter. 

Chander, S. and Fuerstenau, D. W., 1975. Sulphide minerals with thiol collectors the chalcocite diethy dilhiophosphate system. 11th International Mineral Processing Congress, 1 583 - 603 Chander, S., Wie, J. M., Fuerstenau, D. W., 1975. On the native floatability and surface properties of naturally hydrophobic solids, hr P. Somasunfaran and R. G. Grieves(eds.), Advances in Interfacial Phenomena of Particulate/Solution/Gas Systems. AIME Symp., Ser., 150(71) 183-188... 

Heyes, G. W. and Trahar, W. J., 1979. Oxidation-reduction effects in the flotation of chalcocite. Inter. J. Miner. Process, 6 229 - 252... 

O Dell, C. S., Walker, G. W., Richardson, P. E., 1986. Electrochemistry of the chalcocite-xandiate system. J. Appl. Electrochem., 16 544-554 Opahle, I., Koepemik, K., Eschrig, H., 2000. Full potential band stracture calculation of iron pyrite. Computational Materials Science, 17(2 - 4) 206 - 210 Page, P. W. and Hazell, L. B., 1989. X-ray photoelectron spectroscopy (XPS) studies of potassium amyl xanthate (KAX) adsorption on precipitated PbS related to galena flotation. Inter. J. Miner. Process, 25 87 - 100... 

Richardson, P. E., Stout, J. V. Ill, Proctor, C. L., Walker, G. W., 1984. Electrochemical flotation of sulphides chalcocite-ethylxanthate interactions. Inter. J. Miner. Process, 12 73 - 93 Richardson, P. E. and Walker, G. W., 1985. The flotation of chalcocite, bomite, chalcopyrite and pyrite in an electrochemical-flotation cell. 15th Inter. Miner. Process Congr., Cannes, France, 2 198 - 210... 

Woods, R., 1996. Chemisorption of thiols on metal and metal sulphide. In J. O M Bockris, B. E. Conway, R. E. White (eds.). Modem Aspects of Electrochemistry. 29 401 - 453 Woods, R., Young, C. A., Yoon, R. H., 1990. Ethyl xanthate chemisorption isotherms andEh-pH diagrams for the copper/water/xanthate and chalcocite/water/xanthate systems. Inter. J. Miner. Process, 30 17 - 33... 

Young, C. A., Woods, R., Yoon, R. H., 1998. A voltammetric study of chalcocite oxidization to metalstable copper sulphides. In P. E. Richardson, R. Woods (ed.), Int. Symp. Electrochemistry in Mineral and Metal Processing II. Pennington Electrochem. Soc., 3-17... 

Copper is the 26th most abundant element on Earth, but it is rare to find pure metallic deposits. It is found in many different types of mineral ores, many of which are close to the surface and easy to extract. It is found in two types of ores (1) sulfide ores, such as covellite, chalcopyrite, bornite, chalcocite, and enargite and (2) oxidized ores, such as tenorite, malachite, azurite, cuprite, chrysocolla, and brochanite. 

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