Lead production from mining

Country Total smelter production (t/a) Production from mined lead (t/a) Secondary lead production (t/a)... 

On the above basis the energy required for the recovery of secondary lead is of the order of 3 5 per cent of the energy required for primary lead production from sulfide concentrates. If the energy required for mining, mineral separation and supply of lead concentrates to the primary smelters is considered, the total energy for secondary lead recovery is less than 25 per cent of the total for primary lead. 

In Mexico, ores are available containing pyragyrite and proustite, mined entirely for silver extraction, and Mexico derives 50% of its silver production from mines containing these so-called primary silver minerals The other half is, as in the rest of the world, a by-product of copper, zinc and lead production. 

As indicated in the Product Assessment Matrix (Table 5), an environmental assessment of mining metal must consider the energy consumption and the solid, liquid and gaseous residues that result from the various mining processes. Availability of the metals is an additional consideration. Table 6 lists the world reserves of the major metals typically utilized in electronic assemblies. Sn-Ag-Cu alloy is one of the major compositions proposed as a replacement for Sn-Pb solder. Silver is 300 times less available than lead. Half of the silver available comes as a by-product from mining lead, copper and zinc. Antimony and bismuth are also obtained as by-products of lead, copper and silver mining. 

The principal U.S. lead producers, ASARCO Inc. and The Doe Run Co., account for 75% of domestic mine production and 100% of primary lead production. Both companies employ sintering/blast furnace operations at their smelters and pyrometaHurgical methods in their refineries. Domestic mine production in 1992 accounted for over 90% of the U.S. primary lead production the balance originated from the smelting of imported ores and concentrates. 

Total consumption of lead in the United States in 1993 reached 1,318,800 t. Of this, 766,000 t (58%) is allocated to battery use suppHed as either a mixed oxide or as metal. Approximately 95% of batteries are recycled and the lead recovered. In 1993, 908,000 t of lead came from secondary smelters and refiners compared to 350,000 t originating in primary mines and smelters (39). Approximately 51,000 t of lead was consumed in U.S. production of all oxides and chemicals appHcable to all industries other than batteries. Estimates include 8000 t for plastics, 6000 t for gasoline additives, 2000 t for mbber, and 30,000 t for ceramics, glass, and electronics. Lead is not used to any extent in dispersive appHcations such as coatings. 

Mexico, the world s leading producer of silver since the Spanish conquest, obtains virtually its entire silver production from lead—2inc mines in the central cordillera. Mexico retained its dominance in silver production until the discovery of the Comstock Lode in Nevada in 1859. Discoveries in Colorado, Ari2ona, and Montana placed the United States as the world s top silver producer from 1871 until 1900. As these mines played out, Mexico s vast resources returned it to its former position of dominance. 

U.S. silver production from 1985 to 1994 averaged 1588 t/yr. Less than one quarter of this output comes from silver mine districts, however. About half is as by-product of gold mines about one quarter comes from copper and lead—2inc mines. The silver production in Mexico from 1985 to 1994 averaged 2256 t/yr, and Pern, at the southern extremity of the cordillera, where silver is a by-product of copper and lead—2inc mines, averaged 1810 t/yr. 

Hazards of Production. In most zinc mines, zinc is present as the sulfide and coexists with other minerals, especiaHy lead, copper, and cadmium. Therefore, the escape of zinc from mines and mills is accompanied by these other often more toxic materials. Mining and concentrating, usuaHy by flotations, does not present any unusual hazards to personnel. Atmospheric poHution is of Httle consequence at mine sites, but considerable effort is required to flocculate and settle fine ore particles, which would find their way into receiving waters. 

Until the mid-1950s the main raw material source for the European plastics industry was coal. On destructive distillation coal yields four products coal tar, coke, coal gas and ammonia. Coal tar was an important source of aromatic chemicals such as benzene, toluene, phenol, naphthalene and related products. From these materials other chemicals such as adipic acid, hexamethylenedia-mine, caprolactam and phthalic anhydride could be produced, leading to such important plastics as the phenolic resins, polystyrene and the nylons. 

World production of mined lead was 3 331 000 tonnes in 1991 and a further 5 558 000 tonnes was refined by reprocessing. In the same year US eonsumption of Pb in metal produets was 1 125 000 tonnes (ineluding 967 000 tonnes in storage batteries). In addition, some 57 250 tonnes of other oxides and 29 750 tonnes of miseellaneous Pb-eontaining produets were eonsumed. The US market priee of Pb dropped from 1.05/kg in 1990 to 0.40/kg in 1993 due in part to the eollapse in use of PbEta in petrol. 

Most lead used by industry comes from mined ores ("primary") or from recycled scrap metal or batteries ("secondary"). Human activities (such as the former use of "leaded" gasoline) have spread lead and substances that contain lead to all parts of the environment. For example, lead is in air, drinking water, rivers, lakes, oceans, dust, and soil. Lead is also in plants and animals that people may eat. See Chapter 3 for more information on the physical and chemical properties of lead. Chapter 4 contains more information on the production and use of lead. 

Lead is produced from both primary (i.e., mined ore) and secondary (i.e., scrap metal and wastes) sources, and is imported by the United States. In 1997, production from primary and secondary sources was 343,000 metric tons and 1.1 million metric tons, respectively (Smith 1998), and imports reached 265,000 metric tons (Larrabee 1998 Smith 1998). Approximately 1.6 million metric tons of lead were consumed in the United States in 1997 (Smith 1998). Of lead used in 1997, 86.9% was used for storage batteries, 7.8% was used in metal products, and 5.3% was used in miscellaneous applications (Smith 1998). Because of the adverse health effects associated with exposure to lead, its use in paints, ceramic products, gasoline additives (now banned), and solder has declined dramatically in recent years. In 1997,... 

While the first method gives a quick visual overview of ranges, the second, more sophisticated method leads to a more detailed correlation. In both cases, the correspondence between stream sediment and whole rock geochemistry is not perfect since sediments represent only the weathered product of rocks (Pfleiderer et al. 2008). Lithologically homogeneous areas away from mining sites or mineralization are used to derive natural background levels. 

The compounds obtained by the replacement of ring sulfur by carbon, as in the case of penicillins, show somewhat improved antibiotic properties. A free radical— based route has been described for the conversion of fermentation derived cephalosporins to their carbocyclic derivatives. The first step in this sequence consists of the condensation of the cephalosporin sulfone (36-1) with formaldehyde and dimethyla-mine the initial product from the Mannich-like reaction consists of the exomethylene derivative at the position adjacent to the activating sulfone. The product is treated in situ with phenylselenol to give the Michael adduct (36-2). This fragments with an extmsion of sulfur dioxide when heated with the free radical initiator AIBN in the presence of tributyltin hydride the reaction can be envisaged as leading to the... 

Selenium is a very rare element. Scientists estimate its abundance at about 0.05 to 0.09 parts per million. It ranks among the 25 least common elements in Earth s crust. It is widely distributed throughout the crust. There is no ore from which it can be mined with profit. Instead, it is obtained as a by-product of mining other metals. It is now produced primarily from copper, iron, and lead ores. As of 2008, the major producers of selenium in the world were Japan, Belgium, and Canada. The actual amount of selenium produced in the United States was not reported as it is considered a trade secret. 

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