Nickel-based alloys (14% of primary nickel use)
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Nickel-based alloys also have basic recycling similarities to stainless steels but there are three key
differences:
- many alloys are highly complex, containing small amounts of many other metals, some very costly;
- their properties in use tend to be more sensitive to minor chemistry variations than do those of stainless steels; and
- processing routes (e.g., vacuum melting) are usually much less flexible than that used for stainless steel.
The latter point is critical: impurities can in theory be removed but at a high cost. Thus alloy producers make a major effort to preserve the quality and detailed identity of alloy arisings through the production process.
By segregating internal scrap and carefully selecting industrial scrap, the alloy producer can use recycled alloy units -- but in some optimum combination with high quality primary raw materials. End-of-life products may also be recycled but only if the provenance is known and guaranteed.
If the detailed identity of the alloy is lost, or if the alloy becomes contaminated, then the alloy producer will usually prefer sell the scrap or use it for other less-demanding alloys rather than for direct remelting. Hence nickel-based alloy scrap is often sold to scrap-merchants who value it as an ingredient for blending into stainless steel scrap.
High-nickel scrap helps improve the merchant's profitability by enabling him to use more cheap low-nickel scrap units in arriving at the final blend.
Some nickel-based alloys are very challenging to produce and initial yields can be much lower than is typically the case for stainless steels. Low initial yield means that a relatively high volume of internal scrap is generated. But with good identity control, this is usually remelted back into product within weeks if not days.
Mixed turnings and grindings can either be blended into stainless scrap directly or are sometimes remelted
to produce ingots that are then blended. Dusts from the meltshops and fabrication operations (cutting and
grinding) are usually remelted into ingot before sale.
Next: Copper-based Alloys
