Reserves copper

A great part of the global copper reserves is located on the American continents. Reserves and reserve bases, by country, are given in Table 7.2 according to an estimate in 2001 [7.10]. 

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Copper. World copper reserves are estimated at 408.167 > t copper one-fifth being in the United States. Requirements for fertilizer are very... 

Cadmium acts as an antagonist of zinc, copper, and iron. Although cadmium is not transferred to the next generation (not even via milk), it causes a drastic reduction of the copper reserves in the fetus and the copper concentration of the milk (Anke etal. 1970, 1988). 

This corresponds to 3% of the total copper reserves of the world. In the year 2000, production in its own mines was 21000 tonnes, i.e. less than 0.2% of the world production. 

RECOMMENDED DAILY ALLOWANCE OF COPPER. The estimated copper requirement of man is based on balance studies. On the basis of such studies, and in order to allow for a margin of safety, the National Academy of Sciences- National Research Council, recommends a daily copper intake of 1.5 to 3 mg for adults. The requirement for infants and children has been estimated at between 0.4 and 2.0 mg per day. It is emphasized, however, that intake of copper at this level may be too low for the premature infant, who is always born with low copper reserves. It is suggested that infant bottle formulas contain sufficient copper to furnish 100 micrograms/kg of body weight per day. 

Deposits. Selenium forms natural compounds with 16 other elements. It is a main constituent of 39 mineral species and a minor component of 37 others, chiefly sulfides. The minerals are finely disseminated and do not form a selenium ore. Because there are no deposits that can be worked for selenium recovery alone, there are no mine reserves. Nevertheless, the 1995 world reserves, chiefly in nonferrous metals sulfide deposits, are ca 70,000 metric tons and total resources are ca 130,000 t (24). The principal resources of the world are in the base metal sulfide deposits that are mined primarily for copper, zinc, nickel, and silver, and to a lesser extent, lead and mercury, where selenium recovery is secondary. 

Resources. World resources of silver are estimated to be about half a million tons. However, only about 250,000 metric tons are considered economically recoverable reserves. These are associated with ores of copper, gold, lead, and 2inc, and extraction depends on the economic recovery of those metals. Canada and the CIS vie for the greatest reserves of silver in the ground. 

Like selenium, tellurium minerals, although widely disseminated, do not form ore bodies. Hence, there are no deposits that can be mined for tellurium alone, and there are no formally stated reserves. Large resources however, are present in the base-metal sulfide deposits mined for copper, nickel, gold, silver, and lead, where the recovery of tellurium, like that of selenium, is incidental. 

In Moroccan deposits, cobalt occurs with nickel in the forms of smaltite, skuttemdite, and safflorite. In Canadian deposits, cobalt occurs with silver and bismuth. Smaltite, cobaltite, erythrite, safflorite, linnaeite, and skuttemdite have been identified as occurring in these deposits. AustraUan deposits are associated with nickel, copper, manganese, silver, bismuth, chromium, and tungsten. In these reserves, cobalt occurs as sulfides, arsenides, and oxides. 

Exploration. Because it takes years to bring a mine into production, significant new copper deposits are sought and known reserves are expanded more or less continually. These exploration expenditures are highly sensitive to metal market conditions, and, as of this writing, gold is at a better price level than copper. Worldwide exploration continues, however, even after discovery of a deposit and the start of mining. 

More than 200 ores are known to contain cobalt but only a few are of commercial value. The more important are arsenides and sulfides such as smaltite, C0AS2, cobaltite (or cobalt glance), CoAsS, and linnaeite, C03S4. These are invariably associated with nickel, and often also with copper and lead, and it is usually obtained as a byproduct or coproduct in the recovery of these metals. The world s major sources of cobalt are the African continent and Canada with smaller reserves in Australia and the former USSR. All the platinum metals are generally associated with each other and rhodium and iridium therefore occur wherever the other platinum metals are found. However, the relative proportions of the individual metals are by no means constant and the more important sources of rhodium are the nickel-copper-sulfide ores found in South Africa and in Sudbury, Canada, which contain about 0.1% Rh. Iridium is usually obtained from native osmiridium (Ir 50%) or iridiosmium (Ir 70%) found chiefiy in Alaska as well as South Africa. 

Benzoate can be used as an anodic inhibitor and is effective at preventing waterline attack. Phosphate is also sometimes included. Sodium borate (borax) is usually added to the formulation to provide an alkalinity reserve buffer. Typically, a copper inhibitor such as benzo-triazole (BTA) or tolyltriazole (TTA) also forms part of a formulation and is used to provide yellow metal (copper and brasses) protection. 

Ghosh et al. [70] reviewed a few years ago the utihty of C2-symmetric chiral bis(oxazoline)-metal complexes for catalytic asymmetric synthesis, and they reserved an important place for Diels-Alder and related transformations. Bis(oxazoline) copper(II)triflate derivatives have been indeed described by Evans et al. as effective catalysts for the asymmetric Diels-Alder reaction [71]. The bis(oxazoline) Ugand 54 allowed the Diels-Alder transformation of two-point binding N-acylimide dienophiles with good yields, good diastereos-electivities (in favor of the endo diastereoisomer) and excellent ee values (up to 99%) [72]. These substrates represent the standard test for new catalysts development. To widen the use of Lewis acidic chiral Cu(ll) complexes, Evans et al. prepared and tested bis(oxazoHnyl)pyridine (PyBOx, structure 55, Scheme 26) as ligand [73]. 

Major portion of US reserves occur in Alaska, Colorado, Idaho, Nevada, New Mexico, and Utah. In Canada, British Columbia holds the richest reserves of molybdenum. Central and south American molybdenum reserves are found mainly in copper porphyry deposits. Chile s Chuquicamata and El Teniente deposits are two of the largest deposits in the world, and account for 85% of the country s molybdenum reserves. 

As a specific illustration reference may be drawn to molybdenum reserve scenario in the United States. The reserves are mainly grouped under five categories (i) primary, (ii) byproduct of copper ores, (iii) co-product of copper-molybdenum ores, (iv) by-product of tungsten ores, and (v) by-product of uranium ores. These have been presented and briefly elaborated in Table 1.14. It may finally be recorded by way of summary that the present day molybdenum sources in the world today seem to be principally of two main kinds first, the large-tonnage, low-grade, disseminated type of deposit in which molybdenite is the principal economic mineral second, the deposits in which molybdenite occurs as a by-product in... 

By-product of copper ores By-product reserves of copper ores are those contained in ores that are or would be mined mainly for the copper content. Molybdenum recovery occurs as a by-product or secondary product during processing of the ore for the recovery of copper. 

Today, however, pure gold and silver are too scarce and valuable to be used as coins. The United States government keeps huge bars of these metals in vaults, as a reserve. Only copper, the most abundant of the three, is still in daily use as money in the United States. 

World molybdenum production has increased from about 90 metric tons in 1900 — half from Australia and Norway, half from the United States — to 136 tons in 1906, 1364 in 1932 (an order of magnitude increase in 26 years), 10,909 in 1946, and 91,000 tons in 1973. Through the years, molybdenum has been produced in about 30 countries. In 1973, about 60% of the worldwide production was from the United States, 15% from Canada, 15% from the U.S.S.R. and China combined, and 10% from other nations — Chile, Japan, Korea, Norway, and Mexico (King et al. 1973). By 1979, the United States produced about 62% of the world production of 103,000 metric tons, and exported about half, chiefly to western Europe and Japan other major producers in 1979 were Canada, Chile, and the U.S.S.R. (Kummer 1980). In the United States, only three mines in Colorado account for almost 70% of domestic production. Other active molybdenum mining sites in North America are in Arizona, Nevada, New Mexico, Utah, and California molybdenum reserves have also been proven in Idaho, Alaska, Pennsylvania, and British Columbia (Kummer 1980). About 65% of domestic molybdenum is recovered from ores rich in molybdenum the rest is a byproduct from ores of copper, tungsten, and uranium (Chappell et al. 1979). 

Acr Time buffer reserved between crane operations Targeted copper concentration after slag blowing Vou.x Copper content of component %... 

Figure 1.2 The reserve lifetimes of copper and zinc ores, estimated from the annual data supplied by the US Geological Survey.

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