Evening star. [volume] (Washington, D.C.) 1854-1972, 1929-06-02
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is called grade" gold and silver
rock give ore the name Of refractory"
In the old days, when prosqector came
/ across such a deposit he left 1t alone
! and went hunting elsewhere for pure
gold or pure silver. Oftentimes-much
Of the time-there would be no pure
vein to tighten his eyes, and he would
go on leaving mounds OF effort behind
: him. like giant gopher workings.
The reason for his migratory habits
was that a man couldn't afford to load
his mules with base ore and pack 1t for
miles to a single gauge railroad bound
! for smelling plant-and have to pay
a fine, in addition to shipping costs, be-
cause OF the percentage OF zinc, lead,
| etc, that was in the ore. II he had
done that. in the end he would have
been paying the smelling company in
| stead of the other way around. That Is
why those towns OF hope that sprang
up overnight were abandoned so quickly
and completely.
Now. thanks to metallurgical science,
that long-ago abandonment which
caused suspension of at least so per
! cent Of the mining operations IN Colo
| RADIO alone. simply because men were
unable to mine refractory and low-grade
ore at a profit, has taken on the aspect
of an influx.
! And this is where the woman comes
| into the story. One day prospector S
/ wife was washing ore sacks. This worn-
| an. applyinf plenty Of soft water. noticed
! particles of gold floating on the top
along with the suds. This was the be-
| ginning Of what Is now known as the
| selective fotation process. about which
| the United States Geological Survey di-
! crosses from figures to comment, 1T
permits recovery from complex ores
which previously were considered too
lean for utilization"
How Process Works.
However true the story Of the pros
| pectors wife may be, 1t is certain that
there are now an increasing number Of
/ concentrating mills where the selective
| process brings about separation OF
these low-grade ores which caused giant
dump heaps and deserted towns.
There are many types of flotation ma
chimes, but the principle of the process
| Is this: Air Is drawn In at the top of
| the machine and Is agitated with the
| crushed ore and some oil called the re-
| agent-pine tar, for instance. The bub-
bles Of air make q froth and cluster
around the mineral. The pure mineral
| rises to the surface as do soapSuds flows
over the top of the mixture and is
| shipped to the smelter as concentrates
Minerals chiefly concentrated in this
! way are lead. copper and zinc. There Is
usually silica residue Of gold and sill
YER, which goes to its special mill.
| Nowadays every mining camp has a
| concentration mill close by which per-
! forms this valuable Office and thus saves
| the shipper smelling penalties which
| formerly would have made him a bank
rupt.
To put it into figures: Take ton OF
| low-grade ore that would have brought
! about SO so before the prospector's wife
noticed the glittering soapsuds. Nova
| days that ore can be treated at the
centrating mill for approximately $425
a ton. Say that the ore runs 81 100 in
gold. $3.50 in silver. $12 in lead and S.
| in zinc. That makes total Of $24.1e
on one ton of ore. The cost Of the Sc
lective process and the freight on that
ton will not be more than 81. To that
has to be added the cost of smelling
And the miner nets considerably more
tan he got for the crude ore formerly
Nothing Now Wasted.
A fine on rebellious ore now Is rare
1t Is hard to pay fine of so cents q
[ ton for ore having 10 per cent zinc in it
for example, and then have the zinc
wasted, so to speak. Nothing Is wasted
now-not even the pigs whistle, as they
say in the abattoir. They even have
smoke bags in the smelters to catch the
| last precious bit of metal which for
| merly went literally up in smoke
| Thanks to the selective process, pro-
duction figures in q Utah plant alone
| increased more than $4,000, 900 in one
year. The immense quantities of mo-
| lybdenum in those Colorado mines could
not be mined at profit without hota-
ton. The combined output of gold in
Montana. Arizona, Nevada and Utah
equals about quarter Of the country
total, and it comes from low-grade cop
| per ores. In Utah gold Is produced
almost entirely from copper, lead and
lead-zinc ore and the abandoned dumps
The same is true of silver and all the
other metals. And the deserted dumps
in the deserted towns are fast disap-
| pearing.
Leads in Lead Production
The United States now leads the
| world in lead production. The increase
| in late years, says the United States
| Geological Survey, "is largely due 10
improved methods of ore dressings ire
agents. and especially the use of selec-
| tive flotation. The process saves the
| United States from exhaustion Of its
| lead supply, for there are many old
fields still to be recovered" No new
fields are being opened up or prospected
to any extent.
| The immensely lucrative properties of
the Utah Copper Co., the Anaconda
Copper Co. and others could not pay
such dividends without this process.
The ore of the Utah Copper Co., for in
stance, contains but per cent copper,
but the dividends have been large
The methods of mining are improving
rapidly, also. Not long ago, for ex-
ample, the Utah Copper Co. mined in
shafts, very expensive process, espe-
cially for low-grade minerals. Now the
ore Is mined in terraces and the loca-
tions Of the company look not unlike
pyramids. First holes are dug, then
dynamite Is set of in them, then steam
shovelS scoop the ore, a ton at a time,
and dump it into the ore cars, which
convey it the rest of the way.
Similar methods are constantly in
use. The man who sticks to the old
fashioned ways is losing money. There
are hundreds of mines working that
couldn't be worked at all with the old
hand methods, and there are millions
Of tons Of low-grade ore turned into
bank accounts that were nothing but
waste rock before the air drill made 1t
possible to mine at q profit.
This progress in the art of mining
has. to a great extent, made possible
the industrial age-which must have
mineral products If 1t is to carry on.
And 1t is this same industrial age, with
its demands for minerals, that has
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