• Optimizing the product design (select appropriate materials combinations for use and recycling).
• Recycling historic stocks (accumulated from past production) and newly generated current stocks of production scrap.
The strong link between the production of carrier metals and by-product minor metals determines the minor metals supply to the market. When combined with infl exibilities in production, as capacity cannot always respond quickly enough to meet booming demand requirements, significant time delays can result. Market demand for minor metals continues to increase and puts more pressure on finite natural resources. The possibility of mitigating this pressure through substitution is limited, because the same group of metals is used to replace each other. Furthermore, inefficiencies in the manufacture processes increase the gross metal demand (far) beyond the net metal demand required for the final products. Without establishing effective recycling loops for production scrap, as well as for EoL products to stimulate secondary metal production, supply problems may result for a number of minor metals accompanied by corresponding price effects.
Role of Recycling along the Life Cycle
Recycling is an essential part of sustainable metal and product life cycles as it:
• Conserves natural resources by extending the metal reserve base, thereby reducing energy and water consumption, and land use of metal production. Furthermore, the relatively high concentration of (precious) metals in recycled products compared to the ore resource leads to a significant reduction of metal supply-related CO2 emissions.10
• Enhances resource efficiency in the life cycle by recovering useful materials from scrap and EoL products that would otherwise be discarded.
• Contributes to supply security by (a) mitigating gaps between demand from market and primary supply, (b) partially decoupling minor metal production from carrier metal production, and (c) lowering the dependency on a few supplying regions or companies as the regional distribution of scrap and recyclers will be different.
In theory, effective recycling could lead to an infinite metal cycle. Other than for paper or plastics, no "down-cycling" occurs; that is, the quality of recycled metals is identical to primary metals. In practice, however, metals are lost from the life cycle because they cease to be accessible for recovery. The role of recycling is to minimize these metal losses, which can take place on all levels of a metal/product life cycle.
Primary metal production is usually not included when recycling is discussed. Nevertheless, the improved treatment of tailings, slag, or other side streams from mining, smelting, and refining can contribute significantly to resource efficiency and supply of minor metals. Improved efficiency in the primary production combined with the reworking of historic primary stocks will provide a large and rather easy accessible additional metal source for most byproduct metals (e.g., In, Ge, Mo, Re, and Ga). For many coupled metals, like the PGMs, these inefficiencies have already been largely overcome. In manufacturing, the challenges to recycle production scrap usually increase when moving further downstream in the production process.11 As shown in Table 10.5, early manufacturing steps offer a significant recycling potential for many minor metals. In the case of In, Ge, and Ru, this has been applied increasingly over the last years. Metal losses occurring during the product use phase are hardly recyclable due to their mostly dissipative nature.12
The recycling of EoL products will be the key in achieving a sustainable use of metals. Expressions like "urban mining" or "mine above ground" refer to the
10 If the 70,000 t of metals output mix in 2007 from Umicore's Hoboken recovery plant would have been produced from primary sources, the total CO2 impact (base ecoinvent 2.0) of this metal production would have been 1 million t higher than the level actually generated by this operation, which largely treats secondary feed (Hageluken and Meskers 2008).
11 For example, indium recycling gets increasingly more difficult for: target manufacturing ^ spent ITO-target ^ scrapings from the sputtering chamber ^ broken or out-of-spec LCD glass ^ entire out-of-spec or obsolete LCD-monitor.
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