The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1919-09-25
Processes for the Recovery of Zinc From
Low Grade Complex Ores

q fN'SSu N'Ni u
tor, such as the Wetherill, two prod
ucts are obtained: % A blende prod
uct-assaylng about 80 per cent zinc
10 to IL per cent iron, and l per cent
lead which is sold to the zinc smet
ers; and ca, a pyrite product, con-
tanning some lead and about to Z
per cent zinc, which is mixed with
the galena -pyrite product from the
concentrating tables and is sold to the
lead smelters, for whom it is a de-
sirable ore. When this ore is smelted
in the lead blast furnace, the zinc is
lost in the Stag and fume.
electrostatic Separators.
Electrostatic sepaTators are based
on the difference in electrical con-
ductivity of different minerals and on
the attraction of bodies having oppo-
site electrical charges. Most of the
gangue minerals and some of the me-
tallic sulphides, for example. blende,
are poor conductors whereas many
metallic sulphides and other minerals
are good conductors, as pointed out by
Robert H. Richards.
If mixture Of good and poor con-
ductors, in neutral state, be dropped
upon highly charged conducting sur
face, the good conductors Immediate
y receive a charge similar to that of
the SURFACE and are repealed, while the
poor conductors are much more loath
to receive the charge and therefore
not as readily repealed. If. however,
a material charged to a high potential
of the opposite sign be fed to the
above metioned surface, the good con-
ductors, as before, assume Immediate
ly the condition of the charged sur
face and are repealed, while the very
poor conductors, carrying charge OPP
posite to that which the surface car
.ries, by the above law, tend to cling
to that surface, thus making a sharp
er division of the separation. Theoet-
ically the separation of two minerals
a very god conductor and the other
a very poor conductor. but merely that
there be difference in the degree to
which they will conduct electricity
Commercially, of course, there are lin
its to this.
At Midvale, Utah, near Salt Lake
City, at the plant of the Unuited States
Smelling, Refining and Mining COM
pany, an electrostatic concentrating
plant has been in operation since
1909 that is said to save 100000 to
100000 pounds of zinc annually
which before had gone to waste. Zinc
iron middlings, partly furnished by
from custom ore from the district
are passed over a Huff separator. S
f. MacGregor states that the feed
to the mill assays approximately O.O4
ounce gold, 2.5 ounces silver, 2.5 pei
cent lead l per cent copper, % pei
cent iron, % per cent zinc; the sep
arated zinc product assays As to 81
per cent zinc with to per cent iror
and the iron product 10 per cent zinc
Most of the gold, silver, copper, ant
lead Is found in the iron product, ant
this product is smelted in the com
panys lead furnaces.
| The iron product contained about II
per cent zinc. The assays of othe
products, as given by MacGregor
show the same thing; that is, in tn
"iron product or the copper prod
uct''-the product that goes to tn
blast furnace and from which tn
greater part of the zinc has beel
separa ted-there is still anywher
from to IL per cent zinc, and tn
zinc in this product is not recov
cred.
Fiotaton Processes.
In order to concentrate zinc or
by flotation it is generally necessar
to heat the pulp and to use acid.
the ore contains both lead and Yin
the minerals carrying these metals ar
floated, and the lead-bearing miner
ais must be separated from the zinc
bearing minerals. In order to effec
such separation, Norwood Of Aust
ralia, devised selective or preferen
tial process. The following statemen
in regard to this process is taken fror
Metallurgical and Chemical Engi
neering
SeIective FIotation Of Horwood's
Process.
The Broken Hill correspondent