The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1913-07-17


Sir-~There was produced in the
United States in 1912 more than 100000
tons of metallic zinc. worth more than
$4,000, 600. To produce this amount
of metal, OVERLOOKED little fireclay pots
We're constantly in use night and day.
The average life of these Is only a few
weeks. and when one is broken IT must
be replaced As q result. the total
number consumed WAS between one
and two million For each of these pots
il use( q smaller bottelike vessel of
smaller vessels is even shorter The
service required Of these petty utensils
is strenuous. and the handling they
receive is necessarily rough, conse-
quently only the best ohtainable clays
can be used IN their construction, and
great technical skill is required to
make them. A rigorous supervision
must be exercised over every stage
of their evolution. They must be dried
out gradually during several months,
and properly heated afterwards,
before they can go into hot furnace
to replace those which are broken,
They must be handled like crockery,
and yet be charged and emptied once
every tventy-four hours with heavy
iron tools which only strong man
can manipulate, Ii is a triumph OF
manual training which makes 1t posi-
BILE to use them at all. Yet II is as
sumed that they are Indispensable
with a resignation which may be truly
Christian or merely fatalstic.
Careful Handling.
he success in finding suitable clay
tie care taken in preparing it, and all
the little reflnements in manipulation
practiscd and the slight changes IN
size and shape of the vessels adopted
from time to time for economy show
to what extent the art of making them
las been perfected Most Of the ore
chanically concentrated out of material
which contains less than 4 per cent
Of zinc as it goes to the mill. From
this material a rich concentrate con-
tanning between so and 60 per cent
of zinc must be made before the smelt-
ers will look at it. The percentage
loss in this mechanical concentration
Is very high. These two facts. the
successful use Of fragile vessels on A
large scale, and the successful con-
centrating of lean ores, are taken as
evidence Of an advanced stage of de-
velopment in the art of zinc smelling.
This SIS per cent concentrate Is, how
ever, not yet ready to be put into
those precious vessels; 1t must be
roasted to get rid of its sulphur. An
Incomplete roast will not suffice as in
many other branches of metallurgy.
practically all of the sulphur must be
eliminated Here comes in another
evidence of the success achieved in
zinc smelling for the sulphur is reduc-
ed to less than I per cent, and this re
suit is announced with pride. Still an
other evidence Of acquired skill is to
be found in the drawing and casting
'nf the smelted metal, for each of the
little bottles (condensers) attached to
the pots (retorts) must be empttod
from three to five times dav by
~cra ping IT'S contents into ladle
The metal in these ladies' after 1t Is
SKINNED, Is poured into a larger ladle,
e'cir1n,er. 10 poured into a larger lade'
from which it is poured into the molds
after proper cooling. The skill shown
in these operations is admirable.
Mot All Zinc Available.
There is another side of the story
outlined above. 1t is fact that enor-
NOUS deposits Of mineral containing
from to 20 per cent of zinc are easily
accessible. some of them opened by
shafts and drifts, but they are not
available because they are not amen
able to the high concentration possible
on some leaner ores, or because they
cannot be roasted down to less than
per cent Of sulphur. These masses
Of rich raw material are nuisance
where they are found, in working
mines for other metals. and they are
doomed to be irrevocably lost, when
these mines are shut down, unless
happily rediscovered by posterity ano
utilized by a new order of zinc srelt-
ers.
It might be supposed from the fore
going outline that zinc Is connected
with some particularly troublesome
associates. This is not the case. The
elements found with It are those WITT
which every metallurgist is familiar