Copper production

Of the total production of refined copper in the world in the year 2000, reported to be 15 million tonnes, 2 million tonnes or 13% originated from scrap. 

Copper is heavily traded throughout the world. It is true that some refined copper is produced near the mines. However, in many cases the ore is exported from the mining country to industrial regions in other parts of the world. In ancient times the copper ore and metal was moved by caravans to trade routes on the rivers, the Tigris, Euphrates and Nile, and over the sea. Trading took place in the whole Mediterranean world. The situation is the same in our day but in a much bigger world. 

World production of refinery copper totaled 15 milHon tonnes in the year 2000. Twenty-three countries made more than 100 000 tonnes each, as shown in Table 7.6, which also shows a mined/refined ratio for each country. In those cases where producers of refined copper use their own mined copper the ratio has a value near 1. Other countries export much of the mined copper, giving a high ratio, as for Indonesia. Some industriahzed countries with small, or no, copper mines import ore and are big producers of refined copper, Hke Japan and Germany. A low ratio or a value of 0 indicates this. 

Country Refined copper production 1000 tonnes Relation mined/ refinery Country Refined copper production 1000 tonnes Relation mined/ refinery 

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Copper. Domestic mine production of copper metal in 1994 was over 1,800,000 t. Whereas U.S. copper production increased in the 1980s and 1990s, world supply declined in 1994. There are eight primary and five secondary smelters, nine electrolytic and six fire refiners, and fifteen solvent extraction—electro winning (SX—EW) plants. Almost 540,000 t/yr of old scrap copper and alloy are recycled in the United States accounting for - 24% of total U.S. consumption (11). New scrap accounted for 825,000 t of contained copper. Almost 80% of the new scrap was consumed by brass mills. The ratio of new-to-old scrap is about 60 40% representing 38% of U.S. supply. 

The copper and copper oxide ia equations 12 and 13 are from copper production via leaching or from recycled converter slag. 

Composition, temperature, and flow rate of the electrolyte are of great importance to the quafity of the cathode deposit, and changes in any one of these parameters can have a serious effect. Storage and circulation of the electrolyte are also significant. The total volume of electrolyte in a modem tank house is typically 6000 m for a copper production level of ca 500 t/d. 

The copper contained in the electrolyte, anodes and cathodes, and the normal circulating scrap load is equal to about 10% of the annual copper production of a typical electrorefinery. Some refineries (27) have changed from the traditional 25—30 day anode cycle to a 9—14 day cycle using smaller anodes to reduce the copper inventory in spite of the higher resulting scrap load. 

Since 1965 the increased appHcation of leaching technology has had an important impact on copper production. Table 5 shows the relative amounts of copper produced in the United States by various methods. 

Scra.p Copper. The energy required for copper production from scrap is appreciably less than that needed production from ores. If the scrap is of low grade and has to be smelted and refined, the energy consumption is about 45 GJ /1 (43 x 10 Btu/t) of copper (52). Scrap that only requires melting and casting uses about 5 GJ/t (4.7 X 10 Btu/t) of copper. 

Outlook. The energy consumption per unit of copper production is expected to increase as copper grades decline and as faciHties are added for environmental control. A significant reduction in energy consumption could be achieved by installing new faciHties however, energy cost is only a minor component of the total cost of copper production. 

The United States is the world s largest copper producer and in 1989 accounted for approximately 17% of total world production. Table 5 lists copper production in the United States for that year. Most of the copper came from 25 mines. 

Copper compounds, which represent only a small percentage of ah copper production, play key roles ia both iadustry and the biosphere. Copper [7440-50.8] mol wt = 63.546, [Ar]3/°4.t is a member of the first transition series and much of its chemistry is associated with the copper(II) ion [15158-11-9] [Ar]3i5. Copper forms compounds of commercial iaterest ia the +1 and +2 oxidation states. The standard reduction potentials, for the reasonably attainable valence states of copper are... 

The most efficient processes in Table I are for steel and alumintim, mainly because these metals are produced in large amounts, and much technological development has been lavished on them. Magnesium and titanium require chloride intermediates, decreasing their efficiencies of production lead, copper, and nickel require extra processing to remove unwanted impurities. Sulfide ores produce sulfur dioxide (SO2), a pollutant, which must be removed from smokestack gases. For example, in copper production the removal of SO, and its conversion to sulfuric acid adds up to 8(10) JA g of additional process energy consumption. In aluminum production disposal of waste ciyolite must be controlled because of possible fiuoride contamination. 

The copper product is known as blister copper because of the appearance of air bubbles in the solidified metal. In the hydrometallurgical process, soluble Cu2+ ions are formed by the action of sulfuric acid on the ores. Then the metal is obtained by reducing these ions in aqueous solution either electrolytically or chemically, by using an inexpensive reducing agent that has a more negative standard potential than that of copper, such as hydrogen or iron (see Section 14.3) ... 

The mechanism of carbometallation has been explored computationally.77 The reaction consists of an oxidative addition to the triple bond forming a cyclic Cu(m) intermediate. The rate-determining step is reductive elimination to form a vinyl magnesium (or zinc) reagent, which then undergoes transmetallation to the alkenyl-copper product. 

Later developments which have had more impact on copper smelting relate to an approach which combines roasting, smelting and converting steps in one reactor, thereby making the copper production process continuous. The three unique continuous processes tried in operation are (i) the Worcra process, (ii) the Noranda process and (iii) the Mitsubishi process. The principles of the processes are respectively shown in Figures 4.5 to 4.7. 

In the copper production stage, copper sulfide is oxidized to molten copper metal, known as blister copper and so named because when liquid copper cools, the evolution of the residual sulfur and oxygen from the metal as sulfur dioxide gas causes blisters to form on the surface of the metal. The conversion reaction may be shown as ... 

The environmental problem of sulfur dioxide emission, as has been pointed out, is very much associated with sulfidic sources of metals, among which a peer example is copper production. In this context, it would be beneficial to describe the past and present approaches to copper smelting. In the past, copper metallurgy was dominated by reverberatory furnaces for smelting sulfidic copper concentrate to matte, followed by the use of Pierce-Smith converters to convert the matte into blister copper. The sulfur dioxide stream from the reverberatory furnaces is continuous but not rich in sulfur dioxide (about 1%) because it contains carbon dioxide and water vapor (products of fuel combustion), nitrogen from the air (used in the combustion of that fuel), and excess air. The gas is quite dilute and unworthy of economical conversion of its sulfur content into sulfuric acid. In the past, the course chosen was to construct stacks to disperse the gas into the atmosphere in order to minimize its adverse effects on the immediate surroundings. However, this is not an en-... 

Commercial and Environmental Consequences of Sulfur Recovery in Copper Production Systems, in EPD Congress 1996, G. W. Warren (ed.), pp. 773-1013, TMS, 1995. 

FIGURE 3.3 Copper production process. (From U.S. Congress, Copper Technology and Competitiveness, Congress of the United States, Office of Technology Assessment, Washington, DC, 1994.)... 

Copper products Champion, Clean Crop, Nordox Powdery mildew, anthracnose, various blights Various fruits and vegetables Fungicide... 

Ewes from vicinity of copper production plant receiving daily dietary intake of 465 mg/ewe (10.7 mg/kg BW daily) vs. control ewes with average daily dietary intake of 29 mg Cu/ewe (0.67 mg Cu/kg BW daily)... 

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