Mineral chrysocolla

The present description pertaining to copper refers to solvent extraction of copper at the Bluebird Mine, Miami. When the plant became operational in the first quarter of 1968 it used L1X 64, but L1X 64N was introduced in to its operation from late 1968. The ore consists of the oxidized minerals, chrysocolla and lesser amounts of azurite and malachite. A heap leaching process is adopted for this copper resource. Heap-leached copper solution is subjected to solvent extraction operation, the extractant being a solution of 7-8% L1X 64N incorporated in kerosene diluent. The extraction process flowsheet is shown in Figure 5.20. The extraction equilibrium diagram portrayed in Figure 5.21 (A) shows the condi-... 

Kautsky and associates (92, 93) have studied in some detail the lepidoidal silica obtained from a synthetic layerlike colloidal copper silicate which they formulate as [(Si Og)(OH),2][OCuOH]. It has a very high specific surface area similar to the copper mineral chrysocolla (95, 96), which has a specific surface area greater than 300 m g . The corresponding silica has ion-exchange properties, but all the original copper cannot be put back into the structure once it has been removed. 

A variety of mineral ores, mostly copper minerals such as malachite and chrysocolla, were probably the most used green pigments in the past. Various green minerals derived from metals other than copper, such as green earth (see below) were used in confined regions. 

Copper oxide mixed ore - Type 1. The main copper minerals found in these ores include malachite, pseudo-malachite, chrysocolla and some tenorite. These ores also may contain mainly siliceous gangue minerals, including spherocobaltite as the main cobalt minerals. The carbonaceous types also contain an appreciable amount of clay slime minerals. 

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. 

Chrysocolla (CuOxSi02 Cu= 10-36%, SG — 2-2.4) is the most studied mineral of all the oxide minerals. Extensive laboratory studies have been conducted by numerous researchers [9-11]. The laboratory research work indicates that chrysocolla can be floated using the sulphidization method, as shown in Figure 19.4, or by hydroxamate collectors. However, none of these processes have been applied at an industrial scale. 

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. 

Heap (dump) acid leaching of copper sulfide ores is possible with the aid of microbial oxidation. Not all copper minerals are sulfidic, however— malachite, azurite, and chrysocolla are basic copper carbonates—and sulfuric acid heap leaching of low-grade copper carbonate ores can give solutions from which the Cu2+ ion can be separated by solvent extraction (Section 17.3) and copper metal obtained by electrowinning. 

This word chrysocolla of the ancients, which denotes malachite, was not confined to that mineral, as appears particularly from the extended description of Pliny. He mentions the substance dug from the mines in proximity to gold, but he also states that it is a liquid found in the shafts of mines—a slime hardened by the cold of winter till it haB the hardness of pumice. The most valued is from copper mines, the next best from silver mines, and that from the gold mines is inferior. In the mines also an artificial chrysocolla is made by allowing water to percolate into the veins during the winter and spring, and evaporating these in July and August. 

Pliny also states that coeruleum is a kind of sand. It seems probable that besides the blue glass, native blue minerals were also used, as for instance the cyanos of Theophrastus and of Pliny, probably lapis lazuli, and azur-ite, the other kind of cyanos referred to by Theophrastus as containing chrysocolla. 

CHRYSOCOLLA. This mineral, a hydrous silicate of copper probably corresponding to the formula CuiHiSiiOstOHjj. is perhaps a mineral gel, for it usually appears as an amorphous mass, in veins, or as incrustations. Common occurrence as massive cryplocrysiallinc character, possibly orthorhombic extremely rare as small acicular crystals. 

Chrysocolla is a secondary mineral and associated commonly with other copper minerals of similar origin. It is one of ihc less important ores of copper and has a minor use as a gemstone. Among the localities for excellent specimens may he mentioned Cornwall and Cumberland. England Congo Chile Lebanon and Berks Counties, Pennsylvania the Clifton-Morenci Globe and Bisbee districts in Arizona Dona Ana County. New Mexico, and the Untie district. Utah. 

A number of copper-bearing halloysites have been reported associated with copper deposits (Chukhrov et al 1970). They believe Cu, equivalent to as much as 7—8% CuO, can occur in the octahedral sheet. When more than this is present, it occurs as chrysocolla, in part in concordant orientation with the halloysite. It would appear that the poorly crystallized kaolinite minerals will allow a much broader range of isomor-phous substitution than the better crystallized members. 

According to the foregoing interpretation, chrysocolla of ancient times is neither malachite nor a blue copper silicate (the mineral now called chrysocolla) but is a yellow substance, possibly the yellow mineral cadmium sulfide, which appears as a coating on other minerals, chiefly zinc sulfide. This description fits Pliny s text, which describes gold solder (chrysocolla) as a liquid that flows from several mines to give a solid deposit. ... 

G.A. Hope, A. Numprasanthai, A.N. Buckley, G.K. Parker G. Sheldon, "Bench-scale flotation of chrysocolla with n-octanohydroxamate" Minerals Engineering, 36-38 (2012), 12-20... 

Several naturally occurring copper sUicate minerals are known to have been used as pigments, notably the green minerals dioptase (CuSi03.H20) and chrysocolla ((Cu,Al)2H2Si205 (0H)4JcH20). 

Cuprite is a cubic red copper(l) oxide mineral, with chemical formula CU2O. It is a common mineral which forms in the oxidised zones of copper ore deposits (e.g. in Cornwall, England Clifton, Arizona, USA Baha, Mexico Burra-Burra mine, South Australia Chessy, France Linares, Spain Salzburg and Tyrol, Austria Harz, Germany Attica, Greece). Cuprite often occurs with massive form or as well-formed cubes which may be interpenetrant. It may also form as long hair-like threads, in which case it is termed chalcotrichite. It is often found in association with limonite, chrysocolla and malachite (qq.v.) and is sometimes known as red oxide of copper (Rutley, 1988). 

Tenorite is a black copper(II) oxide mineral with composition CuO. Named after the Itahan botanist M. Tenor (1781-1861), tenorite occurs most commonly as a duU, earthy black powder or as botryoidal concretions it may also occur as scales or flakes, or in massive form. Tenorite is a secondary mineral and forms in the oxidising zone surroimding copper deposits (such as in Cornwall, England Bisbee, Arizona, USA Baha, Mexico Burra-Burra mine. South Austraha Salzburg and Tyrol, Austria Harz and Saxony, Germany), often in association with chrysocolla q.v.) and oflier secondary copper minerals. It is also known as black... 

Figure 16. Kinetic curves for the dissolution of elements constituting the chrysocolla mineral, (Cu2.xAlx)H2 x[Si205](0H)4 16 A- mild, 16 B - severe conditions of DD analysis.

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