Gilpin observer., 1909-07-15
INTERESTING REPORT ON
PROPOSED CYANIDE PLANT

trates, SO that as matter Of fact,
while your concentration work has
been splendid, the grade Of these
concentrates has been low, so that
the smelling company has been able
to charge in most Of it's values, and
your profits, and the profits Of all
shippers to you, has been simply
what you have been able to save by
amalsamation, averaging from 40 per
cent. to 55 per cent. Of the total val
ues contained in your ores. This fact
has greatly retarded the development
Of eilpin county and Clear Creek
county, and is entirely unnecessary,
as we will prove in detail and to
your satisfaction in this report.
The condition Of affairs that all
operators, Of any magnitude in Gill
county are now facing is simply this;
that although the shipping grades Of
ore are present, perhaps even in the
same quantity az previously the
depth attained has increased all work.
ing costs to the extent that it is
only \ question Of short time until
they will be prohibtive, unless the
material, up to this time unprofit-
able, become source Of revenue.
II is, therefore, Of vital necessity to
property owners to support every ef-
fort to solve these milling difficulties,
which are as matter Of fact, not
nearly AZ complex as generally be-
iieved.
The question Of available tonnage,
IL the lower grades are included, re-
ouire but little consideration. No.
where on earth is the naturalization
more general and among the multi
tude Of veins, embraced in this Sec
tion, ore in paying quantities and
grade, Is known to exist. II, there
fsre profitable operations can be
demopstrated on $500 grade or over,
IN almost inexhaustabie q0snti4y b
available, on a great part Of which
the development charges, have already
been paid, permitting a cheap Mining
cost. Assuming therefore, that this
grade can be profitabIy handled, the
tonnage factor can be eliminated en-
tireIy, as the probabilities are that
a 1o0o-ton plant could be supplied
with ore for an indefinite time.
The elaborate and exhaustive ex-
perimental work conducted for you
by Mr.. AIsdorf, has demonstrated
several very important facts among
which three may be noted at this
time, first, the ores themselves af-
ter amalsamation are subject to ap-
proximateiy IS per cent. recovery
by eyanidation, under certain eondi-
tions; second, the tails, after amalsa-
nation and concentration, will yield
approximately 80 per cent. Of their
remaining values, by eyanidation, and
third, that the concentrates regard
less Of the fact that they contain
from ~ to ~, per cent. copper will
yield over 80 per cent. Of their gold
contents by eyanidation, under GER
tain conditions, without undue con-
sumption Of cyanide Of potassium,
and therefore at a reasonable cost.
| While on this subject the facts
In the case might just as we'll be
made very plain; the record covering
long period shows that the aver
age grade Of the concentrates shipped
from the mills In this section 10 ap-
proxinateIy $12.oo per ton. Repeated
and coroborative tests show that
this material can be subjected to a
cyanide solution treatment and from
s2 to IS per cent. Of the gold value
recovered; this would leave from is
to 18 per cent, amounting to from
$1.so to $2.16. These concentrates,
locally known as N. G. concentrates,
are now bringing S3.2s per ton =.
o. 3. car Black Hawk, and II the
residues remaining therein could be
reduced to, say S1.oo per ton, they
are still worth the same amount
to wit: 1925 per ton, from which II
becomes plain that total recovery,
or rather, an amount equal to or ex
eeedina Il, can be readily conceived
to be possible.
Having been intimately associated
with the eyanidation Of ores on q
large scale, In q district that eoulc
not possibly operate without the use
Of this process, we feel fully eompe
tent to analyxe your situation anc
the data resulting from your exten
xivs experiments and though eonsIs
family loo< Inn fnr anna dAtAll al