Steel recycling

A large fraction of the iron and steel produced today is recycled scrap. Since scrap does not require reduction, it can be melted down directly in an electric arc furnace, in which the charge is heated through its own electrical resistance to arcs struck from graphite electrodes above it. The main problem with this process is the presence of tramps (i.e., copper from electrical wiring, chromium, nickel, and various other metals) that accompany scrap steel such as crushed automobile bodies and that lead to brittleness in the product. Tin in combination with sulfur is the most troublesome tramp. Only the highest quality recycled steel—specifically, steel with no more than 0.13% tramps—can be used for new automobile bodies, and usually reprocessed scrap has to be mixed with new steel to meet these requirements. 

Steel derived from new pig iron produced from ores and from recycled steel has better properties than iron for most uses. World steel production currently hovers around 1.33 times world pig iron production, a reflection of the recycled metal content. Again, we have some countries, like China and the U.S.A., whose national steel consumption exceeds even their very large scale of production (Table 14.2). 

M. A. Goksel and W. M. Mathias, Recycling steel plant fine materials by using the MTV cold bond process , in Proceedings of Fourteenth Biennial Conference, IBA, 1975, pp. 105-17. 

The values shown in Table 1 are dramatic, and they show that although wood construction clearly has environmental impacts, these impacts are small compared to those of steel. When use of recycled steel is considered, the differences between wood and steel narrow, but wood retains a significant advantage. As part of the... 

Copper, which is known as a tramp element in recycled steel produced from steel scraps, was found to be segregated by heating at 800°C [1997Suz]. The surface segregation seems to increase the thickness of the oxide layer formed at room temperature. 

The speed of technological advance coupled with the introduction of legislation can lead to very rapid development of recycling industries. The remarkable changes which have occurred in the level of utilisation of recycled steel and glass, and the relative attractiveness of different materials are classic examples, and also serve as indicators of the important consequences which follow the introduction of collection schemes, such as bottle banks and other forms of pre-segregation at municipal and industrial levels. 

SOFC stack remanufacturing will reduce the contribution to all impacts from the baseline more than any other design alternative investigated because life cycle impacts are expected to track with plant steel consumption not fuel consumption. If remanufacturing is not an option, the use of recycled steel improves the life cycle profile. 

Figure 5.19 Remember to recycle your cans. As well as aluminium cans, we can also save energy and resources by recycling steel cans.

A possible source of soil contamination results from recycling industrial wastes for fertilizer. According to data compiled by the Environmental Working Group (EWG) during the 1990s, approximately 25 million kg per year of potentially toxic wastes were used to prepare fertilizers that contained elevated levels of arsenic, cadmium, lead, radioactive materials, and dioxins. A potential source of heavy metal pollution in fertilizers is ash from furnaces used to recycle steel, commonly processed to provide zinc in zinc-deficient soils. 

Figure 6.5 The BTRC UHP water jetting process (a) recycled steel needles (b) recycled fluff (c) recycled powder, average 400 pm and (d) SEM micrograph of recycled powder. Reproduced with permission of Big Tyre Recycling Corporation, Martelaarslaan, Belgium. 2014, Big Tyre Recycling Corporation...

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