Recycling of Nickel-Containing Materials in Automobiles

An estimated 40 million End of Life Vehicles (ELVs) arise annually. The metallic components of these vehicles are largely recycled but up to 10 million tonnes per annum of non-metallic waste remain unrecovered worldwide and are generally landfilled (a small proportion is incinerated).(1) This is the auto shredder residue (ASR).

Recycling of automobiles can be represented as:

Recycling Nickel in Autos

Source: Management of end-of-life vehicles in Ontario: Report, Proceedings and Draft Recommendations of the RCO Roles and Responsibilities Forum, April 28, 1999.

A very high proportion of the ferrous and nonferrous metals in an automobile are recycled. Non-magnetic nickel-containing stainless steel and nickel metal would be recovered in the non-ferrous fraction. The Bureau of International Recycling claims 99.5 % of nonferrous metals are recovered in the EU using the above technology and media separation plants.(2) Another estimate has been made by the UK Consortium for Automotive Recycling (CARE) as "typically, the shredding industry is capable of recovering more than 95% of the metallic content of an ELV".

The nonferrous metal from shredded motor vehicles can be separated using high-tech sorting machines but global realities favour the export of nonferrous scrap mixtures to the Far East for hand-sorting. Coded "Zorba" by the International Scrap Industry Institute (ISRI), the specification is configured to suit shredders with eddy current sorting equipment, so fluid based media separation, more elaborate than eddy current, is not required. Simsmetal listed a typical analysis of 65% aluminum, 15% zinc, 8% red metals, 1% insulated wire and 1% stainless steel.(4) Hand-sorting can achieve up to 99% purity for the following metal fractions: "copper, brass, radiators, cast aluminum, sheet aluminum, stainless steel, zinc die cast, zinc sheet, wire/cables ends, metal breakage with ferrous attachment, etc."(3)

It would appear that the nonferrous metal is effectively separated into its constituent components and with nickel-containing stainless steel scrap selling for quite a high price, there is no reason to believe it is not being recycled. Nickel-containing stainless steel content of automobiles and accessories has declined from approximately 44% to approximately 36% of the total nickel content.(4) Older vehicles that make up the bulk of current ELVs should therefore contain more nickel stainless steel. A reasonable assumption might be that about 40% of the nickel used in automobiles is recycled via stainless steel.

However, what about the non-stainless steel nickel-containing products which make up more than one-half of the nickel used in automobiles? Plated metal products are likely separated into the substrate metal categories, mainly steel and brass. Technologies exist for the recycling of plated plastic parts but they do not appear to be widely in use. It is likely that this nickel migrates with the ASR or where plastics are separately collected, with the "general plastics" stream.

The nickel contained in the ASR that is sent to landfill is truly lost to all recycling loops. How much is it? Stuecheli(5) found that that ASR is very heterogeneous with nickel content ranging from 0.4 to 2.8 g/kg with a mean of 1.2 g/kg. Assuming that the worldwide annual scrapping of ELVs yields 10 Million tonnes of ASR(1), this translates into 12,000 tonnes of nickel lost to landfill each year. Insofar as total nickel use in automotive applications has ranged from 128,600 tonnes in the past (more accurately representing vehicles being scrapped today) to 75,300 tonnes(4) more recently, this nickel loss represents as little as 9% and as much as 16 % of nickel used in automobiles. Finally, it should be noted that ASR normally comes from scrap blended from automobiles, white goods and general scrap. Since most of the nickel comes from the automotive component, the mean nickel content noted above may be lower than estimated. Therefore, it might be the case that as much as 20% of the nickel in automobiles is lost to landfill.

This then leaves approximately 40% of automotive nickel that is recycled into other metals (steel, copper, brass, aluminum etc). While certain nickel-containing alloys might benefit, it is likely that most of this nickel becomes part of the residual of elements permitted in the alloy specification.

In conclusion, it is estimated that approximately 40% of the nickel contained in automobiles and parts is reused for its nickel content via parts reuse and nickel-containing stainless steel recycling. Another 40% or so is recycled into other metals and becomes unavailable to the nickel recycling loop. And finally, about 20% is generally dispersed, including to landfill.

References

  1. The Material Composition of Shredder Waste in the UK, Ambose C.A., Singh,M.M. &Harder M.K., Waste and Energy Research Group, School of the Environment, University of Brighton http://www.caregroup.org.uk/latest.shtml
  2. Bureau of International Recycling website: http://www.bir.org
  3. Global market helps keep scrap sorting a low-tech affair, American Metal Market, September 23, 2002.
  4. Research study commissioned by the Nickel Institute 2003.
  5. Thermal Treatment of Shredder Residues, A. Stuecheli, Colorado School of Mines Workshop June 25-27, 2002 Recycling Metals from Industrial Wastes