Metal, recycling

Much of the technology used in the reclamation of metals from metal-bearing wastes was developed by the mining iadustries. The primary means of recycling metal from metal and alloyed scrap is via pyrometaHurgy (see Metallurgy). 

Nickel. Around 56,000 t of nickel were recycled from scrap in 1994. This is just over one-third of the consumption of the metal. The only mining and smelter in the United States was idle in 1994, although INMETCO (EUwood City, Peimsylvania) was a primary consumer of recyclable metal in the production of stainless steel. Almost one-half of all nickel went into the production of stainless steels with an additional 29% in superaHoys and... 

When nonrenewable mineral resources are processed for metal extraction and the metals extracted are utilized in various ways and in diverse forms, they become potentially available for reclamation and recycling. Recycled metals produced by the extraction and refining of metallic wastes are known as secondary metals, whereas metals produced from primary ores are termed primary metals. A classification of recyclable metalliferous resources such... 

DOI, Recycled Metals in The United States, A Sustainable Resource, U.S. Department of the Interior,... 

SmithGR. 1996. Lead. Recycling—Metals, Minerals Information Team, US. Department of the Interior, U.S. Geological Survey. Lead Statistics and Information, Minerals Yearbook, Recycling Metals, http //minerals.er.usgs.gov/minerals/pubs/commoditv/lead/... 

The main difference between these two methods is that in MBT method, mixed waste is separated into organic, recyclable, metal, inert, and high-caloric... 

Table 1.2 Examples of double and triple bond hydrogenation with recyclable metal NPs in ILs alkenes, dienes, arenes, ketones, and aldehydes. 

Finely divided aluminium powder or dust forms highly explosive dispersions in air [1], and all aspects of prevention of aluminium dust explosions are covered in 2 recent US National Fire Codes [2], The effects on ignition properties of impurities introduced by recycled metal used to prepare dust were studied [3], Pyrophoricity is eliminated by surface coating aluminium powder with polystyrene [4], Explosion hazards involved in arc and flame spraying of the powder are analysed and discussed [5], and the effect of surface oxide layers on flammability was studied [6], The causes of a severe explosion in 1983 in a plant producing fine aluminium powder are analysed, and improvements in safety practices discussed... 

Metal-recovery operations, phosgene in, 18 810-811. See also Metals recycling Metal reductions hydrazine, 13 569 to liquid metal, 16 141-146 Metal refining, 16 149-151 barium application, 3 349 limestone in, 15 38-39 Metal removal, in electrochemical machining, 9 593-595 Metal-rich phosphides, 19 59... 

Indirect electroreductions use metal complexes, metal ions, and metal organic compounds as mediators. Their characteristic features are well documented both in monographs [8, 11, 13, 15, 17] and reviews [249-252]. This chapter reviews the potential of such mediators for electroreduction, which involve recyclable metal and nonmetal complexes, but not enzymatic systems. 

Aluminum scrap is one of the salvaged and recycled metals that is less expensive to reuse than it is to extract the metal from its ore. In other words, it takes much less electricity to melt scrap aluminum than it does to extract aluminum from bauxite. 

The Advanced Recovery Systems, Inc. (ARS) developed the patented, ex situ DeCaF hydrometallurgical technology to decontaminate fluoride by-products and to recover recyclable metals. The technology uses a proprietary acid mixture to digest the fluoride matrix, freeing radioactive contaminants (e.g., uranium, thorium, or radium) and hazardous contaminants (e.g., lead, arsenic, or chromium). Radioactive elements are recycled or disposed. Metals are also recycled, and fluoride is recovered as a high-value salt for aluminum smelting. 

Supported chelating agents serve three major functions, i.e., concentration, elimination, and recycling metal ions. 

Recycling metal ions is part of the concentration process noted above. It can typically be achieved by treatment of the sorbed metals with dilute nitric acid. This is a strong acid, and the nitrate ion is not a strongly coordinating anion. In addition, recycling can be a useful means of paying for the removal process. Tkn example of this was a laboratory bench-scale experiment to treat water from the Berkley Pit, recycle the copper and sell the copper to help pay the processing costs. The Berkley Pit [11] was once an open pit copper mine that was opened in 1955 and closed in 1982. 

We should conserve and recycle metals whenever possible because it is far cheaper to produce metals from recycled products than from ore. Environmentally sound exploration of new reserves is also required. Ore nodules discovered on the ocean floor, for example, contain as much as 24 percent manganese and 14 percent iron. Significant quantities of copper, nickel, and cobalt have also been found in this submarine terrain. Perhaps mining of the ocean floor may one day replace the mining we now do on land. And in the not too distant future, perhaps the mining of metal-rich asteroids in space will become a reality. 

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