Carbonate ores

Molten magnesium chloride can be formed by the direct carbochlofination of magnesium oxide obtained from the calciaation of magnesium carbonate ores or magnesium hydroxide [1309-42-8]. 

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. 

Other substances— for example, the silicate ores, the carbonate ores, the titanium minerals— may be similarly grouped for pmposes of experi-piental study, but it is hardly necessary here to make a complete inventory of such groups. 

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 ... 

Manganese is distributed widely in nature, mostly as oxide, silicate, and carbonate ores. Manganese ores often are found in association with iron ores in small quantities. The element, however, does not occur naturally in native form. Manganese is the twelfth most abundant element in the earths crust. 

Industrial calcium carbonate (CaCOs) is mainly produced by extraction/milling of natural ore. Suitable ore-bodies include chalk, limestone, marble, and travertine. Sufficiently pure ore-bodies are selected to allow direct exploitation. The main applications include paper, paints, plastics, pharmaceuticals, etc. Luminescence and LIBS (Fig. 8.3) sorting may be used for calcium carbonate ore radiometric sorting. 

The LIBS technique may be extremely useful for sorting of fluorite ores. Figure 8.8 clearly demonstrates the opportunities of time-resolved LIBS in comparison with the steady-state method in the case of fluorite-carbonate ores. Fluorite and calcite both has Ca as a major element and its emission lines dominate in the steady-state spectra making sorting impossible. After a delay of several ps the intensity of Ca lines is strongly diminished and a F line with a longer decay becomes visible in the fluorite spectrum. 

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. 

Calcination of the Ores.—The carbonated ores of this country arc generally prepared for the blast furnace by a process of calcination which burns away all volatile matters, and concentrates the metal. For this purpose the Ores are accumulated in large ]leaps, generally in an open field, and mixed with carbonaceous matters, each as small coal. Some of the black benda have sufficient coal in their composition to effect their calcination. After a heap of several hundred tons is oolleoted, a fire is kindled at the windward end, which gradually passes on through the whole mass and burns for several days, producing a very high heat, often sufficient to reduce and fuse some of the metal, which, however, is not desirable. 

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. 

Side rite. FeCO-,. corresponding to 48.2 X P e. 51.86/ CO , sp gr 3.83 3.88. white to greenish-gray and brown, contains variable amounts of calcium, magnesium, and manganese, varies from dense, line-grained and compact to crystalline, sometimes referred to as spathic iron ore. or black-band ore. The carbonate ores are calcined... 

The collector oil molecules are amphiphilic, with their polar groups exhibiting some affinity for particular metal ores, and so create a hydrophobic particle surface on adsorption. They can be anionic, cationic or non-ionic. Organic xanthates and thiophosphates are often used for sulphide ores and long-chain fatty acids for oxide and carbonate ores. 

Calcite and whitings (RI 1.5-1.7) are naturally occurring calcium carbonate deposits. The lowest cost grades are ground limestone or the mixed calcium magnesium carbonate ore, dolomite. Synthetic calcium carbonate is also used as an extender, but it is more expensive. 

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. 

Many ores of zinc arc concentrated by flotation before smelting. Sulfide ores and carbonate ores are then converted to oxide by roasting ... 

Okita P. M. and Shanks W. C. (1992) Origin of stratiform sediment-hosted manganese carbonate ore deposits examples from Molango, Mexico, and TaoJiang, China. Chem. Geol. 99, 139-164. 

Okita P. M., Maynard J. B., Spiker E. C., and Force E. R. (1988) Isotopic evidence for organic matter oxidation by manganese reduction in the formation of stratiform manganese carbonate ore. Geochim. Cosmochim. Acta 52, 2679-2685. 

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

Magnesium occurs widely in carbonate ores, but most Mg comes from salt brines and from the sea (Figure 22-5). Sea water is 0.13% Mg by mass. Because of its low density (1.74 g/cm ), Mg is used in lightweight structural alloys for such items as automobile and aircraft parts. 

The earliest observations leading to the concept of chemical- or absolutehardness, go back to the days of Berzelius. It was noted that some metals occurred in nature as their sulfide ores, and others as their oxide or carbonate ores. Table 1 puts this in more quantitative terms. Listed are the cohesive energies, AH°, for a number of binary metal oxides and sulfides, MX. 

Lead content in the earth s crust is about 4 The most important lead minerals are PbS (86.6% Pb), 3PbS Sb2S3 (58.8% Pb), PbCOs (77.55% Pb), 2PbS %S-Sb2S3 (42.4% Pb) and PbCl2PbC03 (76.0% Pb). Lead bearing ores such as PbS composition are the most abundant. In the oxidized (carbonate) ores lead exists in the form of PbC03 compound. 

Over the period 1955-1961, the electrolytic plant processed only calcined zinc oxide having a composition of 60% Zn, 3-4% Pb and 0.03% Cd. The zinc oxide was produced by calcination of the fumes from the Waelz process at temperatures from 1420 to 1470 K. Zinc carbonate ores, Zn-Fe residues and other zinc-bearing materials were used as raw materials in the Waelz process. After enhancement of the electrolytic zinc plant in 1962, the importance of roasted sulphide concentrates was continuously growing in the feed. Currently, only the calcine from fluid-bed roasters is processed. Table I shows the analysis of the raw materials processed over the period 1998-1999. 

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