6
H. Roberts
should be classified as primary or secondary lead is open for discussion. CHR Metals
accounts for this feed as secondary feed). Higher prices since the mid-2000s have
encouraged this activity, especially in China, where zinc leach residues are routinely
processed in Waelz kilns to enhance overall zinc recoveries and to recover other
minor metals, with the resulting slag then sold on to lead smelters for the eventual
recovery of the contained lead. Relatively high lead contents in zinc concentrates
(and vice versa) were not uncommon in China in the past although, in more recent
years, new mills (concentrators) employing modern technology have resulted in an
improvement in concentrate quality in China perhaps reducing the availability of
second-pass feed. The balance of the secondary lead feed into primary lead smelters,
after taking account any allowance for second-pass material, is from true secondary
sources. These may be other industrial wastes or residues but also includes battery
scrap, especially battery paste. Another source of lead feed which has seen some
increase in more recent years has been recovered as a by-product from the processing
of electric arc furnace (EAF) dusts undertaken principally for the zinc content which
is sold to zinc smelters as crude zinc oxide.
Technology, such as QSL, Kivcet, and TSL (Ausmelt/ISAsmelt), replacing sinter
machine/blast furnace operations in the West in the 1990s, was intended to improve
environmental performance, compared to more traditional sinter machine/blast furnace operations, and also to widen the range of feed that could be treated, especially
secondary lead-bearing materials. In some cases, this was also driven by the need
to process related zinc refinery residues with increasing environmental pressures on
the long-term storage of zinc leach residues. In China, the adoption of domestically
developed flash smelting furnaces using bottom and side-blowing oxygen enrichment, in addition to some limited investment in Western smelting technologies, has
been primarily the result of tightening environmental regulations and better enforcement of these rules. This has also meant greater opportunities to utilise a mix of feed
materials, including a share of secondaries. In China, zinc smelters can no longer store
their leach residues indefinitely. Many have chosen to further process the residues
through Waelz kilns which will generate some secondary lead-bearing feeds while
some are investing in western flash furnace technologies to directly treat zinc leach
residues. All of these developments have added, and will continue to add, to the
production of lead from secondary sources which are in addition to lead produced
from recycling scrapped batteries.
Global Growth of Secondary Lead Production Since 1990
CHR Metals estimates that global secondary lead output amounted to a little over
2.9 Mt in 1990 and accounted for slightly more than half of all refined lead production. Around 300 kt was accounted for primary smelters processing secondary
lead-bearing feed with the balance produced by companies largely recovering lead
H. Roberts
should be classified as primary or secondary lead is open for discussion. CHR Metals
accounts for this feed as secondary feed). Higher prices since the mid-2000s have
encouraged this activity, especially in China, where zinc leach residues are routinely
processed in Waelz kilns to enhance overall zinc recoveries and to recover other
minor metals, with the resulting slag then sold on to lead smelters for the eventual
recovery of the contained lead. Relatively high lead contents in zinc concentrates
(and vice versa) were not uncommon in China in the past although, in more recent
years, new mills (concentrators) employing modern technology have resulted in an
improvement in concentrate quality in China perhaps reducing the availability of
second-pass feed. The balance of the secondary lead feed into primary lead smelters,
after taking account any allowance for second-pass material, is from true secondary
sources. These may be other industrial wastes or residues but also includes battery
scrap, especially battery paste. Another source of lead feed which has seen some
increase in more recent years has been recovered as a by-product from the processing
of electric arc furnace (EAF) dusts undertaken principally for the zinc content which
is sold to zinc smelters as crude zinc oxide.
Technology, such as QSL, Kivcet, and TSL (Ausmelt/ISAsmelt), replacing sinter
machine/blast furnace operations in the West in the 1990s, was intended to improve
environmental performance, compared to more traditional sinter machine/blast furnace operations, and also to widen the range of feed that could be treated, especially
secondary lead-bearing materials. In some cases, this was also driven by the need
to process related zinc refinery residues with increasing environmental pressures on
the long-term storage of zinc leach residues. In China, the adoption of domestically
developed flash smelting furnaces using bottom and side-blowing oxygen enrichment, in addition to some limited investment in Western smelting technologies, has
been primarily the result of tightening environmental regulations and better enforcement of these rules. This has also meant greater opportunities to utilise a mix of feed
materials, including a share of secondaries. In China, zinc smelters can no longer store
their leach residues indefinitely. Many have chosen to further process the residues
through Waelz kilns which will generate some secondary lead-bearing feeds while
some are investing in western flash furnace technologies to directly treat zinc leach
residues. All of these developments have added, and will continue to add, to the
production of lead from secondary sources which are in addition to lead produced
from recycling scrapped batteries.
Global Growth of Secondary Lead Production Since 1990
CHR Metals estimates that global secondary lead output amounted to a little over
2.9 Mt in 1990 and accounted for slightly more than half of all refined lead production. Around 300 kt was accounted for primary smelters processing secondary
lead-bearing feed with the balance produced by companies largely recovering lead