Elk City mining news. (Elk City, Idaho) 1903-1913, 1905-05-13
Place and Value of Small Scale
Ore Tests.
By Ernest H. Simonds in Mining and
Scientific Press.
NUMBER II-CONCEUDED.

DuC IL is lull WORKING size, Ill ldcC, IHe
complete mill will only be multiplied
ton of this single unit, thus testing the
process and machinery mechanically and
giving a chance for remedying any me-
chanical defects which may develop.
Most testing works are equipped only
with light machinery, and old mills have
not the substantial construction and i'm
proved design to, give large capacity,
which in a great measure determines
cost. With the unit plant right at the
NINE tests of large tonnage, extending
over days and weeks can be made, thus
rendering the small errors in the clean
up of slight effect on the results and
giving exact data as to extractions,
costs and even as to wear and tear;
and the millmen have an opportunity to
acquire skill in applying the method to
the ore and in adjusting the machinery.
4. 1t enables the owners to realize
on the ore taken from development
workings with least expense and at
once, thus paying at least in part, the
cost of development; and the metallur-
gical development goes along with the
mining development, problems of treat
ing the ore are being solved at the same
time as are those of finding and mining
it. This is too frequently not done; no
doubt you can call to mind at once, as
did within half a minute, from your own
experience, three or four mines where
ore of rich milling grade was proven in
quantity several years before it could
be worked to a reasonable extraction.
Furthermore, if only one unit of the
plant is erected at first, the temptation
will be removed, in fact it will be i'm
largely down the canyon or at least into
the tailings pond or perhaps into the
treasury of the railroad company the
values in the rich ore usually taken from
a new mine, before possible difficulties
in it's treatment have been gotten over
Such education is too expensive; it is
cheaper to get it in a one-unit plant.
For all of these reasons, therefore,
Jul JCoO (ellA OCOI NC q OllC-
unit plant at the mine. But in arriving
at this conclusion, we have made one
assumption, namely, that laboratory
tests will correctly indicate the most
advantageous process in a general way
and with enough particularly so that
we can install the machinery best adapt
ed to the ore for the unit plant. We
must, therefore, consider how far reli-
ance may besplaced upon the data OBJ
tained in smell scale tests in directing
us to the choice of the correct type of
plant. How far are they reliable as
preliminary tests? What are their
faults? What their advantages?
In order that results of laboratory
tests may be reliable, it is necessary,
of course, that the sample on which the
tests are made should correctly repre-
sent the ore which is to be worked. The
only proper way to take this sample is
to take samples throughout the mine in
exactly the way that would be done if
the mine were being examined for sale.
In quartering down the sample to get
the assay pulps, two quarters are saved
after the sample has been crushed to
one-half inch mesh. After the samples
have been assayed, so that we know
which represent ore and which waste,
an amount of each one of the samples
representing ore is weighed out which
corresponds to the stopping width at the
point where the sample was taken.
these samples are thoroughly mixed,
and we have sample for the tests
which is an epitome of the mineable ore
in the deposit as shown by the present
state of development of the mine. Be-
sides this average composite sample, or
which all extraction tests will be made,
specimens should be taken of varying
aspects of the ore, showing the condi.
ton of the gold in rich specimens, the
different sulphides in the mine and the
character of the wall rock These are
taken to show the form of the gold, sill
yer, copper or lead minerals, and tC
make it possible to determine, by assays
of different specimens, with which min.
erals the values are combined.
To show what can be done by small
tests in showing how to redhee the val
ues of the tailings in a mill already
running, will give the following result.
on sample &C tailings assaving So. 81