Copper carbonate ores

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. 

Nonferrous Metal Production. Nonferrous metal production, which includes the leaching of copper and uranium ores with sulfuric acid, accounts for about 6% of U.S. sulfur consumption and probably about the same in other developed countries. In the case of copper, sulfuric acid is used for the extraction of the metal from deposits, mine dumps, and wastes, in which the copper contents are too low to justify concentration by conventional flotation techniques or the recovery of copper from ores containing copper carbonate and siUcate minerals that caimot be readily treated by flotation (qv) processes. The sulfuric acid required for copper leaching is usually the by-product acid produced by copper smelters (see Metallurgy, extractive Minerals RECOVERY AND PROCESSING). 

A.4 Identify all the chemical properties and changes in the following statement Copper is a red-brown element obtained from copper sulfide ores by heating them in air, which forms copper oxide. Heating the copper oxide with carbon produces impure copper, which is purified by electrolysis. ... 

The reddish metal was already known in prehistoric times. It occasionally occurs as a native metal, but mostly in conspicuous green ores, from which it is extracted relatively easily. It is convenient to work, but not very hard. Not very optimal as a tool ("Otzi the Iceman" had a copper axe with him). Only through the addition of tin is the more useful bronze obtained. Its zinc alloy is the versatile and widely used brass. Copper is one of the coinage metals. Water pipes are commonly made of copper. Its very good thermal and electrical conductivity is commonly exploited (cable ), as well as its durability (roofs, gutters), as the verdigris (basic copper carbonate) protects the metal. Cu phthalocyanines are the most beautiful blue pigments. Seems to be essential to all life as a trace element. In some molluscs, Cu replaces Fe in the heme complex. A 70-kg human contains 72 mg. 

The sulphidization process, which was first successfully applied on a commercial scale on lead carbonate ores, is currently the most popular method used during treatment of oxide copper ores that contain malachite and carbonaceous gangue. The commonly used sulphi-dizers are Na2S 9H20 and NaHS, with xanthate or xanthate ester. 

The initial research work on oxide zinc flotation dates back to the 1930s at the University of Liege, Belgium [7]. This research work was based on the earned experience of flotation of oxide copper ores. Fatty acids, which are good collectors for copper carbonates, were not applicable because the gangue minerals in the zinc oxide ores were also floatable in the presence of fatty acids. 

In most industrial processes, copper is produced from the ore chalcopyrite, a mixed copper-iron sulfide mineral, or from the carbonate ores azurite and malachite. The extraction process depends on the chemical compositions of the ore. The ore is crushed and copper is separated by flotation. It then is roasted at high temperatures to remove volatile impurities. In air, chalcopyrite is oxidized to iron(ll) oxide and copper(ll) oxide ... 

Native copper ore is crushed, concentrated by washing with water, smelted, and cast into bars. Oxide and carbonate ores are treated with carhon in a smeller. Sulfide ore treatment is complex, hut. in brief, consists of smelling to a matte of cuprous sulfide, ferrous sulfide, and silica, which molten matte is treated in a converter by the addition of lime and air is forced under pressure through the mass. The products are blister copper, ferrous calcium silicate slag, and SO . Refining is conducted by electrolysis, and the anode mud is treated to obtain the gold and silver. See Fig. I. 

Copper Carbonate (Basic), CuCOi CutOH j. dark-green monoclinic crystals, insoluble in cold HiO decomposes in hot H 0, soluble in potassium cyanide. Malachite, a copper ore. is of this composition. Refined compound is used as a pigment. 

Copper metal is mined as one of several copper-containing ores. One of these ores contains copper in the form of malachite. Malachite exists as a double salt, Cu(0H)2-CuC03. It can be thermally decomposed at 200°C to yield copper(II) oxide, carbon dioxide gas, and water vapour. 

Ores of copper native copper, cuprite, chalcocite, chalcopyrite, malachite, azurite. Metallurgy of ores containing native copper, oxide and carbonate ores, sulfide ores. Gangue, flux, flotation, roasting of ores, matte, blister copper. Cupric compounds copper sulfate (blue vitriol, bluestone), Bordeaux mixture, cupric chloride, cupric bromide, cupric hydroxide. Test for cupric ion with Fehling s solution. Cuprous compounds cuprous chloride, cuprous bromide, cuprous iodide, cuprous oxide. Covalent-bond structure of cuprous compounds. 

Copper oxide and carbonate ores are readily reduced by heating with coke and a flux ... 

Ammonia complexation has also been employed, primarily for nickel-copper separations but also for copper recovery, when this is from native copper or copper oxide ores [15]. The dissolving process is thought to involve formation of soluble cuprous ammonium carbonate [53] (Eqs. 13.51 and 13.52). 

Metals are found in ores in the Earth s crust. Ores are rocks that contain minerals from which metals can be extracted. Most metals are too reactive to exist on their own in the Earth s crust. Some metals exist as metal oxides, such as iron oxide and aluminium oxide, some as carbonates, such as copper carbonate, and some are sulfides, including zinc sulfide. A few metals are not fovmd combined with any other element because they are not reactive -they occur native. The best example of this is gold. 

Azurite a-zho- rIt [F, fr. azur] (ca. 1868) n. Natural blue pigment derived from the mineral, azurite, a basic copper carbonate. The mineral occurs in various parts of the world in secondary copper ore deposits where it is frequently associated with malachite, a green basic carbonate of copper. Perkins D (2001) Mineralogy. Prentice-Hall, New York. Kirk-Othmer (1996) Encyclopedia of chemical technology pig-ments-powders. John Wiley and Sons, New York. Lewis PA (ed) (1985-1990) Pigment handbook, 2nd edn, vols 1-4. Wiley-Interscience, New York. 

The first metal to be obtained from an ore was copper, but we do not know when or where this chemical process was first performed. We can speculate that somehow a piece of the ore malachite (basic copper carbonate) was accidentally heated with charcoal, perhaps when a lump of malachite was used as one of the stones in a fire ring. By 4000 BC both copper and lead were in use in Egypt and Mesopotamia. By 3000 BC both regions were producing bronze, probably by smelting copper and tin ores together. 

Many examples of the usefulness of the concept could be quoted. It is interesting to note, for example, that many years ago Berzelius pointed out that some metals occur naturally as oxide and carbonate ores while others occur as sulphides. We see now that the metal ions that are hard acids such as magnesium, aluminium and calcium occur in combination with the hard bases carbonate and oxide, while the soft metal ions such as copper, mercury and lead occur in combination with the soft base sulphide. The hard acid BF3 forms a stable complex with the hard base F but not with the soft base CO, whereas the soft acid BH3 forms a strong coinplex with CO. It may also be noted that the hard acid par excellence is, of course, the proton H and there is no evidence, even in the strongest superacid medium known [15], that the proton forms a stable complex with the soft base CO, although the latter forms many stable complexes with soft metal ions. 

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