The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1917-10-18
IDEAS IN ZINC METALLURGY
(The Mining American)

1t Is well known that the reduction
of zinc from its ores has never been
commercially performed by as simple
or inexpensive methods as prevail in
the metallurgy of the other base met
ais. The worlds spelter continues to
come largely from small Belgian-type
retorts whose charging, firing, tapping
and drawing involves intermittent du-
ties and relatively great amount of
labor for their capacity
Metallurgists have endeavored, for
many years, to invent cheaper schemes
for smelling zinc ores. Their chief de-
sire is to invent process that is
steady or continuous instead of in
terrupted. II strikes the layman as
peculiar that science has not evolved
such a method. Here we are, follow
ing a primitive practice in securing
one of the modern worlds most i'm
portant metals, whereas notable ad-
vance has been made in the branches
of metallurgy that cover practically
every other metal-base precious and
rare.
Cost Averages Higher.
The present cost of smelling zinc
sulphide ores in our country probably
averages higher than ten dollars per
ton, Most of our zinc is derived from
blende or sphalerite The nom sulphide
ores of zinc-such as calamine, the
silicate, and smithsonite, the carbon
ate-may be smeted more cheaply
because they do not require prelimin-
airy roasting to remove sulphur.
Continuous smelling of zinc has
been effected by numerous inventors
particularly those employing the cleo
trio arc, but the expense has been
found abnornrally high and such pro-
cesses have generally failed to attain
industrial importance,
Zinc may be reduced from ores by
wet or chemical methods Hydro
metallurgy of this metal steadily gains
favor. In such schemes, the metal Is
first put into solution by solvents
tsuch as acids or gases) and is then
withdrawn from the liquor by chemi-
cal precipitation or by electrolysis.
There will unquestionably be many
significant advances made along these
lines and in time, the old fashioned
fire method will be relieved of its mo-
rotony in spelter production.
Papers Stimulate Interest.
AT the October meeting in st. Louis
of the American Institute of Mining
Engineers, several papers treating up
on these matters will be presented by
recognized authorities. The papers
and their attending discussions will go
far toward stimulating general inter-
est in this subject
For years, large plants have produc-
ed zine oxide directly from ores Such
works can handle larger tonnages of
ore than can the ordinary retortihg
plants and treatment cost per ton is
considerably less but in general, they
too, operate upon an intermittent
plan.
There is strong market for the OK
ide, especially If 1t be almost or quite
pure. 1t is in demand as paint pig
ment and in making lithopone while
the rubber industry absorbs tremend-
Gus quantities. All white and light
colored rubbers contain a considerable
amount of this oxide which must be
pretty free from oxide of lead Zinc
oxide is large component of automo-
bile tires. to which it imparts tensile
strength, durability and road adhe-
sion.
Manufacture Not Smelling
But the manufacture of zinc oxide
usually is not smelting--it involves no
fusion of the gangue in the ore 1t is
rather a sort of igneous concentration. :
There are a few small plants in which
fusion is performed in special types of
blast furnaces, the zinc being driven !
off as the oxide fume and collected /
while Stag is tapped from the bottoms
of the furnaces. In most oxide plants, !
however, the reactions are conducted |
in reverberatory furnaces at temper
atures too low for fusion. In this !
practice no fluxes are used, the ground /
ore (Which is first roasted if it be sui
phide) being mixed with anthracite I
slack and then charged into f,irna COS I