8 6 Helmut Gutenberger and Wojciech Pastuszczyn on ... - Messer

10 : Cover story
Oxygen burner – the key
to more efficiency
Nowadays lead is used in
storage batteries such as
car batteries, from which it
is also recycled.
acid. The process begins in remelting plants with the
breaking down <strong>and</strong> grading of the storage batteries.
This is followed by the lead smelting process, i.e. the
melting <strong>and</strong> refining.
In shaft furnaces or direct reduction plants, the
roughly broken down batteries have their sulphuric
acid removed <strong>and</strong> are then processed in a mixture with
additives such as coke, limestone <strong>and</strong> iron. The air that
is required for combustion is enriched with oxygen.
Again, this process produces slag <strong>and</strong> raw lead.
Recycling with rotary furnaces involves separating
the metallic lead fraction (lattice) <strong>and</strong> the lead oxide
fraction (paste) from plastic <strong>and</strong> sulphuric acid. By
adding coke, iron <strong>and</strong> soda, these lead fractions are
then processed into raw lead, with slag again being
produced in the process. Depending on its quality, the
slag is disposed of or used in road construction. The
energy required for the melting process in rotary furnaces
is delivered by means of fuel/oxygen burners.
Refining
Refining involves purifying the raw lead of the
traces of other elements that are still contained in it
<strong>and</strong> producing the lead alloy requested by the customer.
After removing the copper with sulphur, the residual
elements antimony, arsenic <strong>and</strong> tin are removed
through selective oxidation with oxygen. The leadcontaining
dross that is produced in this process is
recycled <strong>and</strong> remelted.
Use of oxygen
Combustion processes are optimised by, on the one
h<strong>and</strong>, preheating the fuel <strong>and</strong> combustion air <strong>and</strong>, on
the other, adding oxygen. The best combustion effi-
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on air 09 · 2008