The Anaconda standard. [volume] (Anaconda, Mont.) 1889-1970, 1899-08-08
regarding the value of the Seven Devils
copper fields, and that is, sit is a great
Charcoal as a Precipitant of Gold From
Auro- Cyanidcs.

camp
Charcoal as a Precipitant of Gold From
Auro-Cyanidcs.
John 1. Lowles, Inst. M. NJ, in Mining
and Scientific Press.
In the district of Victoria this method il
used to the almost total exclusion of any
other, in many cases probably in imita-
ton, rather than with any definite
grounds for its superiority over the zinc
process.
The methods are identical down to the
extractor house, which in typical plant
contains 1s9 tubs, each feet inches high,
feet 1 inch in diameter at the top and
l foot inches at the bottom. In the GEN.
ter of the bottom of each tub are two
small wooden cleats. inches apart on
which rests glazed drain pipe, inches in
diameter, Hanged end downwards. Cen
ter pipes and tubs are filled with char
COAL coarse for inches from bottom and
medium size to within inches of top
of center pipe, with about 3 inches out
side and inches inside the tub of coarse
charcoal again. On the top of the char
COAL inside the tub and all round the pipe,
is a wooden lid to keep the charcoal from
floating and blocking the outlet pipe.
Another form of tub much used has no
center pipe, but there is a false bottom
of filter cloth, while on the top of the
charcoal is hinged lid with feed pipe let
into it.
The preparation of the charcoal ie i'm
portant, impurities being prejudicial and
wasteful. Fine stuff Is Objectionable. be-
ing a bad filtering medium and also pass
ing through into the sumps. Heavy COM
pact charcoal again Is not so efficient as
that which is light and porous. gold be-
ing deposited throughout the whole Of
light charcoal so that compact material
en- a,G f-
moreover, more difficult to incinerate.
The charcoal is ground and sieved to
three sizes-coarse medium and fine, the
latter being discarded. The other sizes
are thrown into separate tanks of water,
and only that which floats used.
The tubs in above works are arranged in
two groups, the first of IA filters in "a
sets of six each, for strong solution; the
second of "a, in Is sets of three each, for
alkaline wash O.04 per cent. Key and
weak solution.
The solution passes down the center
pipe of the first tub in each set, coming
W on the outside and flowing over the lid
through a one-inch pipe to the next tub
of the series, and so on, finally passing
away to it's own particlkVlr stump. The
top filter catches most OF the gold and
when fairly charged is removed, each of
the remaining five being moved UP one
step and newly charged tub being
placed in the sixth position. The filter re-
moved is drained of some of it's solution
and emptied into a large box with filter
bottom. where the rest of the solution Is
run off into the stump. leaving the aurifer-
Gus charcoal ready for the furnace room.
A tub occupies first position for about
three days.
The efficiency of precipitation Is, OF
course, an important point. The strength
of solution does not appear to affect the
precipitation at all, the percentage ex-
traction being uniformly high; the solu-
ton going out of the sumps in one estab-
lishment rarely showing more than 3i2
! grains per ton Original value not stated),
while 0.04 per cent. Key solutions are sue
cessfully precipitated. The gold in the top
| filters is considerably purer than that
| caught in the lower ones, and the author
| suggests that means might be taken to
| keep the contents of the top filters sepa-
| rate. Frequent tests show a steady dim
| mutton in the value CT the gold, taking
| place downwards through set till the
| bottom tub is nearly pure silver.
| The exact action of the charcoal has
never. as far as the writer knows, been
experimentally demonstrated, but he thinks
| it may be due to the hydrogen and hydro
carbons remaining in the charcoal, the re-
| suit being the formation Oh hydrocyanic
| acid and free gold. This Hey represents
| a
| From the filter house the aurferous
| charcoal is conveyed to the furnace room
| where it is incinerated in four reverbera-
tory furnaces, each 10 feet long. The ash
| Is sieved through 900-mesh trommel and
| the coarser residue returned to the fur
! mace. The fine stuff, or "ash, containing
about so per cent. of gold. is then smelted.
The author thinks 1t doubtful whether
the process will supercede the zinc pro-
ht1t following
tages:
1. A high-class bullion is produced-one
| welI-known mine receives ga per ounce for
cyanide gold.
3. Percentage extraction is high regard
less of strength in solution.
8. In spite of the large amounts of aurif-
ercus charcoal to be handled the waste
is easily got rid of by burning. and the
| ash Is easily smelted without the neces-
| stv of treating with strong acids or care
full oxidizing roasts with some unavoida-
Bile loss).
One great disadvantage is the greater
| chances of loss through the immense bulk
of stuff to be handled and the higher cost
of the operation itself. The cost of char
coal precipitation with charcoal at Cd per
40 pounds works out at .29d per ounce
of gold. Zinc precipitation with zinc at
4hd per pound would cost 2.25d per ounce
of gold. Labor works out at 0.I6Sd per
tor of charcoal and 0.3S2d per ton for
| zinc.
To recover the gold from the lash" at
these works costs Is per ounce. bullion SOC
fine, exclusive of labor, as against about
I'd for zinc shines, which would probably
average not more than 800 fine.
| There remains the question of increased
outlay for plant and buildings. but these
are not very serious. Considering the
same works, 1873 tubs cost e247 los, zinc
boxes would require but a small portion
of this.
Mr.. Bryce Writing Novel.
From Literary Notes.
| Mr.. Bryce, M. p, is, ii appears, in