Recycling critical raw materials from waste electronic equipment

Recycling critical raw materials
from waste electronic equipment
6.1 Precious metals
Advanced refining methods have existed for a long time for the recovery of high purity
precious metals such as gold, silver, palladium and platinum from various secondary
materials such as old jewelry, industrial catalysts, automotive catalytic converters, dental
products and, of course, electronic waste (see GFMS 2005, UNEP 2009). Precious metals
from the waste electronic equipment sector are normally recovered as an extremely valuable
by-product from secondary copper production. Suitable components such as PCBs (e.g. from
notebooks) which contain both appreciable amounts of copper as well as smaller amounts of
precious metals are usually subjected to a melting process (pyro-metallurgy). The copper
functions as what is known as a collecting agent for the precious metals, i.e. the precious
metals are very successfully bound in the developing fluid copper phase. The plastic fraction
from the electronic waste is used as an energy carrier for the processes. Non-precious
components (e.g. glass, aluminum) are bound in the slag. After tapping the copper phase,
this is followed by a further processing stage (electrolysis of the raw copper) for purifying the
copper. The precious metals (gold, silver, platinum and palladium) accumulate in significantly
increased concentration in what is known as the anode sludge. Special processes, which
differ in detail in the individual companies, are used to recover the precious metals with a
high degree of purity at very high recovery rates (sometimes significantly more than 90% cf.
GFMS 2005).
Europe is home to leading companies which recover the secondary copper and precious
metals mentioned above in state-of-the-art plants. Due to the fast-growing quantities of
electronic waste, considerable expansion of the processing capacities is taking place. In
2011 the German copper group Aurubis expanded its total recycling capacity at the Lünen
site in North Rhine-Westphalia. The throughput in the existing KRS bath smelting furnace in
Lünen rose from 275,000 tons to 350,000 tons per year (EUWID 2011a). According to
information from the company, the plant is particularly suited to the treatment of complex
recycling materials such as metal-containing industrial wastes, copper-rich shredded material
and electrical and electronic waste. Further capacity for recycling electronic wastes is located
at Aurubis' works in Hamburg.
In Scandinavia, the Swedish mining and metals group Boliden also own copper smelters
which recover secondary copper and precious metals from electronic waste. The group's
recycling capacities for electronic waste are currently undergoing considerable expansion:
from 45,000 to 120,000 tons per year (EUWID 2011b).
In Belgium (in Hoboken near Antwerp) the company Umicore processes a wide range of
secondary materials. Each year high yields of valuable metals are recovered (see Figure)
from over 350,000 t of raw material (catalytic converters, PCBs, mobile phones, industrial
intermediate products and residues, slag, fly ash, etc.) using a complex pyro-metallurgical
process.
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