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,...

Sulfide Ores ores. In the Zairian ores, cobalt sulfide as carroUite is mixed with chalcopyrite and chalcocite [21112-20-9]. For processing, the ore is finely ground and the sulfides are separated by flotation (qv) using frothers. The resulting products are leached with dilute sulfuric acid to give a copper—cobalt concentrate that is then used as a charge in an electrolytic cell to remove the copper. Because the electrolyte becomes enriched with cobalt, solution from the copper circuit is added to maintain a desirable copper concentration level. After several more steps to remove copper, iron, and aluminum, the solution is treated with milk of lime to precipitate the cobalt as the hydroxide. 

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). 

Central metal cation Monatomic metal cation to which all the ligands are bonded in a complex ion, 409 Cerium (IV) oxide, 147 Chadwick, James, 517 Chalcocite, 539... 

With the important copper ore, chalcocite, Cu2S (the process called roasting the ore) ... 

FIGURE 16.10 Three important copper ores (from left to right) chalcopyrite, CuFeS, malachite, CuC03-Cu(0H)2 and chalcocite, Cu2S. 

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

Teine fahorc, gold-fieldite, hessite, native bismuthinite, fahore, hakite, native electram, bomite, chalcocite, quartz, sericite, calcite. 

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. 

Chalcocite and covellite are also oxidized by ferric sulfate, with the resulting ferrous sulfate reoxidized back to the ferric form. This mechanism is termed indirect bacterial oxidation. Ferric oxidation of chalcocite can also be seen to proceed through two stages, with very quick conversion to covellite in the first stage, and the completion of the oxidation in the second stage ... 

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. 

Ammoniacal leaching of chalcocite ores108-110 generates two Cu streams, an enriched ore— covellite—which can be treated in a conventional smelter, and a fairly concentrated aqueous solution (ca. 5M, pH 8.5-10) containing ammine complexes,... 

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