Zinc Refining Overview

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Zinc Refining Overview
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Objectives
After competing this unit you will be able to

• Describe the operation of each
• major process area within zinc refining

• State which of the unwanted elements
• are separated from the zinc at each
• processing stage and

• List the sequence in which the unwanted
  elements are
• removed.

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The Refining Concept
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Zinc refining is a scientific process of refining
zinc metal.
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Although zinc concentrate doesnt appear to be
anything more than garden variety dirt it does
in fact contain a high concentration of zinc and
other elements.
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To be more precise, the proportion of these
elements in the concentrate is as follows. One
kilogram of zinc concentrate contains on
average...
1kg
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The final zinc metal product that is sold to our
customers must be 99.995 pure.
Super High Grade (SHG) zinc must have this level
of purity in order to be sold on the
international metals market.
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We now know that for every 1 kilogram of zinc
concentrate approximately 60 of the ore is zinc
and the remaining 40 is made up of unwanted
minerals.
Unwanted elements
Desired element
Therefore, to achieve this level of purity all we
have to do is separate the zinc from the unwanted
minerals. If only it was that simple!
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Unfortunately these minerals are not present as
separate elements in the concentrate but are
chemically bonded together in a variety of
compounds. Some of these include
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Imagine that this is a particle of zinc
concentrate. The sequence in which we separate
the unwanted elements is
S
S
Fe
S
Si
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Each of these impurities are removed at a
different stage in the refining process.
S
S
Fe
S
Si
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If we were to look at the concentrate as it
progressed through the refining process this is
what we would see.
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Summary
We have now looked briefly at the principles of
zinc refining. It is a process of refining a
zinc concentrate until we have the required zinc
purity. The refining process involves separating
out unwanted elements such as