The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1923-04-05
Engineering and Mining
Journal-P

journal PfeSS.)
With the high prices of lead and
zinc that are now obtaining, added
incentive is given to the production of
those metals Lead is particularly
scarce, and no large deposits of lead
ores have recently been discovered or
developed, as has been the case with
copper. Metallurgists are therefore
turning to the economic treatment of
a class of material which has so far
been impossible to smelt without ex-
cessive losses-namely ores contain
ing the sulphides of lead and zinc in
Intimate mixture, usually with silver
and gold and small quantities of other
metals. Should this so-called com
pick ore problem be solved. as there
is every indication that it will be. the
supply of lead and zinc will be aug
mented sufficiently to take care of all
probable requirements for some time.
These lead-zinc ores are not only
common in certain districts of the
west, as in Colorado and Idaho par
ticularly but are found in many other
parts of the world, Australia and In
dia being notable examples.
Until now, selective flotation has
been the chief method of separation
employed on a commercial scale. This
has perhaps achieved its greatest de-
Velopment in Australia. AS an exam
pie of what has been accomplished
there, the Broken Hill South, Ltd. in
the year ended June go 1922, treated
an ore containing IA per cent lead and {
IL per cent zinc Four products were {
made; concentrates containing 6S per I
cent lead and 7 per cent zinc; zinc l
tailings S4 per cent lead and II per I
cent zinc; quartz tailings containing l
per cent lead and per cent zinc: I
and slime containing IL per cent lead e
and iS per cent zinc. The slime was a
hen subjected to selective flotation. d
a lead product containing go t
Der cent lead and per cent zinc was g
secured and a zinc residue contain I
ng "a per cent lead and 10 per cent D
inc. \
Several other companies are treat s
ng ores of q similar nature, among D
hem being the Zinc Corporation. the "
ulphide Corporation, and the Brok-
Il Hill Proprietary, the latter using
he Bradford sulphur dioxide process.
IN this continent the new plant of
ne Consolidated Mining & Smelling
Dmpany at Trail, B. c., is an excell-
Mt example of selective flotation. Sc
he lead is first floated and then the
nc, in second machine. The rough til
ad concentrate is cleaned, and the
Hing from the zinc machine is re-
Gated to recover more of the zinc. co
he zinc concentrate contains some
ad, which is partially eliminated by al
bling. Several other American
ants have been more or less sue
ssful with selective flotation pro- uc
sses The practice represents a big ,
vance over any method of separa- tri
m formerly used, but it has disad- n,
ntages. Where the lead and zinc
lphides are finely divided and in An
nately mixed, it is manifestly i'm
ssible to secure clean lead or zinc 7
iOeHlidteS WITHOUT inner grinding TIL
IN is desirable. Thus the process
adapted only to certain ores. and T.
IN on these there is more lead in
zinc concentrates and more zinc An,
the lead concentrates than the 7,
tallurgist would like. r. ,
lore recently, several processes s
ed on chemical rather than physi-
principles have been developed. And
it seems probable that these will
e more universal application The
will result in higher recoveries. s,
nplete descriptions can not yet be
lished, for the processes are still iAno
he development stage and the final II
nod to be used will depend upon Don
sriment. The Coolbaugh process DR.
soon be tried out on a CONNER
scale by the American Smelling The.
efining company at Durango. Colo Oh
ore is given a sulphate roasting And
wed by a water teaching. This Ae