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S. Grund and E. van Genderen
zinc smelters mainly produce zinc from ore concentrates. In addition to the ore
concentrate, zinc smelters feed an average of 10–15% secondary raw materials into
their processes. Mostly these are so-called crude oxides (Waelz oxides), which are
enriched zinc containing flue dusts from steel production from galvanized steel. In
some cases, the recycled zinc content in the smelter feed can be higher—in specific
cases up to 100%.
An additional tonnage of 4–5 Mt of zinc is recycled in re-melt processes, in the
copper or in the zinc compound industry without passing through the zinc smelters.
Different from many other metals, there is not one single technology for zinc recycling. Instead for the most important zinc uses, tailor made recycling technologies
are well-established:
• Zinc sheet and zinc die casted parts are re-melted. Over 95% of zinc sheet scrap
is recycled in Europe [8]. Re-melting zinc requires only 5% of the energy that is
needed to produce primary zinc from ores [9].
• Galvanized steel is re-melted in the steel industry, e.g., electric arc furnace. Zinc
ends up in the flue dust (EAF dust) and is further concentrated in the Waelz process.
The Waelz/crude oxide is a welcome raw material for primary zinc production at
less costs than concentrates supply, its use often being limited by the available
tonnage. Other potential technologies for zinc recycling from galvanized steel are
being tested at pilot plant or conceptual phase. 11% of steel scrap from building and construction is reused, e.g., in Germany, while 88% are recycled in the
steel industry [10]. All EAF dusts that are produced in Europe are recycled. With
the emerging markets for galvanized steel a significant growth at global scale is
expected [11, 12, 13].
• Zinc as an alloying element in brass is recycled by the copper industry. There it is
used for brass production or alternatively returned to the zinc industry.
• Various technologies are applied to recycle zinc from residues, wastes, and byproducts. Often zinc in these recycling loops is directly used to produce zinc
compounds without passing through zinc smelters, thus saving costs, energy and
raw materials.
Two approaches commonly used to assess recycling rates for zinc are the Recycled
Content (RC), the fraction of secondary zinc in use, and End of Life (EoL) recycling
rate, the fraction of zinc recycled relative to the amount available at EoL. For zinc, as
for metals in general, the EoL recycling rate provides the most informative information on the success of recycling. Higher EoL recycling rates relate to effective waste
management systems and capacity for recycling products at the end of their useful
life (Fig. 3).
The recycled content for zinc, as for other metals, will continue to increase over
time but will remain below 100% due to dynamics of market growth and durability
of zinc metal products. For example, it may require decades before zinc metal that
is used today, e.g., as sheet for roofing or to galvanize steel, becomes available for
recycling [14]. Moreover, the tonnage of zinc that is used today is much higher than
what has been put into use decades ago.
S. Grund and E. van Genderen
zinc smelters mainly produce zinc from ore concentrates. In addition to the ore
concentrate, zinc smelters feed an average of 10–15% secondary raw materials into
their processes. Mostly these are so-called crude oxides (Waelz oxides), which are
enriched zinc containing flue dusts from steel production from galvanized steel. In
some cases, the recycled zinc content in the smelter feed can be higher—in specific
cases up to 100%.
An additional tonnage of 4–5 Mt of zinc is recycled in re-melt processes, in the
copper or in the zinc compound industry without passing through the zinc smelters.
Different from many other metals, there is not one single technology for zinc recycling. Instead for the most important zinc uses, tailor made recycling technologies
are well-established:
• Zinc sheet and zinc die casted parts are re-melted. Over 95% of zinc sheet scrap
is recycled in Europe [8]. Re-melting zinc requires only 5% of the energy that is
needed to produce primary zinc from ores [9].
• Galvanized steel is re-melted in the steel industry, e.g., electric arc furnace. Zinc
ends up in the flue dust (EAF dust) and is further concentrated in the Waelz process.
The Waelz/crude oxide is a welcome raw material for primary zinc production at
less costs than concentrates supply, its use often being limited by the available
tonnage. Other potential technologies for zinc recycling from galvanized steel are
being tested at pilot plant or conceptual phase. 11% of steel scrap from building and construction is reused, e.g., in Germany, while 88% are recycled in the
steel industry [10]. All EAF dusts that are produced in Europe are recycled. With
the emerging markets for galvanized steel a significant growth at global scale is
expected [11, 12, 13].
• Zinc as an alloying element in brass is recycled by the copper industry. There it is
used for brass production or alternatively returned to the zinc industry.
• Various technologies are applied to recycle zinc from residues, wastes, and byproducts. Often zinc in these recycling loops is directly used to produce zinc
compounds without passing through zinc smelters, thus saving costs, energy and
raw materials.
Two approaches commonly used to assess recycling rates for zinc are the Recycled
Content (RC), the fraction of secondary zinc in use, and End of Life (EoL) recycling
rate, the fraction of zinc recycled relative to the amount available at EoL. For zinc, as
for metals in general, the EoL recycling rate provides the most informative information on the success of recycling. Higher EoL recycling rates relate to effective waste
management systems and capacity for recycling products at the end of their useful
life (Fig. 3).
The recycled content for zinc, as for other metals, will continue to increase over
time but will remain below 100% due to dynamics of market growth and durability
of zinc metal products. For example, it may require decades before zinc metal that
is used today, e.g., as sheet for roofing or to galvanize steel, becomes available for
recycling [14]. Moreover, the tonnage of zinc that is used today is much higher than
what has been put into use decades ago.