Copper Ores

natural mineral formations containing sufficient copper to make economically feasible the extraction of the metal from these ores. Of the 170 known copper-bearing minerals, 17 are currently used on an industrial scale: native copper, Cu; bornite (peacock ore), Cu₅FeS₄ chalcopyrite (copper pyrite), CuFeS₂; chalcocite (copper glance), Cu₂S; covellite, CuS; bournonite, CuPbSbS₃; the gray copper ores tetrahedrite, Cu₁₂Sb₄S₁₃, and tennantite, Cu₁₂As₄S₁₃; enargite, Cu₃AsS₄; cuprite, Cu₂O; tenorite, CuO; malachite, Cu₂[CO₃](OH)₂; azurite, Cu₃[CO₃](OH)₂; chrysocolla, CuSO₃ - nH₂O; brochantite, Cu₄[SO₄](OH)₆; chalcanthite, CuSO₄ · 5H₂O; and atacamite, CuCl₂ · 3Cu(OH)₂.

Several industrial types of copper ores are distinguished according to the mineral composition, the grain size of the minerals and the nature of their mutual interpenetration, and other factors. These ores are classified according to their chemical composition and the presence of copper sulfides, oxides, carbonates, or sulfates into the following natural groups: sulfide ores, oxide ores, and mixed ores. The sulfide ores, which account for 90 percent of the world production of copper, are the most important.

As a rule, copper ores are complex: in addition to nonmetallic minerals (quartz, sericite, barite), they often contain pyrite; pyrrhotite; the sulfides of zinc, lead, nickel, cobalt, molybdenum, antimony, and other metals; and admixtures of trace elements, such as Cd, Se, Te, Ga, Tl, Ge, In, and Re. The aforementioned associated components, including also the S in the sulfides, are of considerable value, sometimes as much as 50 percent of the value of copper extracted from the copper ore.

Based on texture, ores are divided into (1) massive ores, which have a copper content of more than 3 percent and which are suitable for direct smelting (content of other metals is commercially insignificant), and (2) disseminated ores (average copper content, 1-2 percent; low copper content, 0.4-1.0 percent), which are concentrated by means of collective or selective flotation, frequently with the preliminary application of heavy suspensions. The hydrometallurgical method of processing low-quality, especially oxidized, ores, including the application of various extracting reagents, is being increasingly used.

According to the methods of formation and morphology of the ore bodies and the composition, several industrial types of copper ore are distinguished (see Table 1).

In terms of the reserves and extraction of copper, porphyrytic ores (porphyry copper) account for the largest share—more than 60 percent of known reserves and 40 percent of world production (excluding the socialist countries). They are widely distributed in many countries, including the USSR (Kounrad, Almalyk, Kadzharan), Bulgaria, Hungary, Chile (Chuquicamata and elsewhere), the USA (Bingham Canyon, Utah, and other locations), and Canada (Valley Copper, B.C.). Copper-bearing sandstones and shales, which account for about 30 percent of the world’s known reserves and 20 percent of the world production of the metal (excluding the socialist countries), constitute the second largest source of copper. The largest deposits of this type are located in the USSR (Dzhezkazgan, Udokan), Zambia, and Zaïre.

The copper-pyrite ores play an important role, accounting for more than 5 percent of the world’s known copper reserves (excluding the socialist countries). Such deposits are located in the USSR (Urals), Spain (Riotinto), Yugoslavia (Bor), Turkey (Ergani-Maden), and other countries.

Copper-nickel deposits, which account for 10 percent of the known reserves of copper (excluding the socialist countries), are

primarily processed for the nickel. Such deposits in the USSR are the Noril’sk and the Kola groups of deposits. They also occur in Canada (Sudbury, Ont.) and the USA (Alaska, Stillwater).

The copper-bearing polymetallic (lead-zinc-copper) ores are widely distributed throughout the world. The skarn copper ores, which are genetically related to moderately acidic granitoids, and the vein and other types of deposits are of secondary importance in the overall balance of reserves and mining of copper.

As of 1973, the principal copper producers in the capitalist world are (copper production in terms of concentrates, thousands of tons) the USA (1,490), Zambia (717), Chile (716), Canada (708), and Zaire (428). These countries account for more than 81 percent of the world production (excluding the socialist countries).