IMPROVE- MENTS IN THE REDUCTION OF GOLD, SILVER, AND COPPER ORES
Year: 1860

page_text: LETTERS PATENT to John McCulloch, of San Francisco, in the United
States of America, Analytical Chemist, for the Invention of "IMPROVE-
MENTS IN THE REDUCTION OF GOLD, SILVER, AND COPPER ORES."
Sealed the 8th May 1860, and dated the 1st March 1860.
PROVISIONAL SPECIFICATION left by the said John McCulloch at the
Office of the Commissioners of Patents, with his Petition, on the 1st
March 1860.
I, JOHN MCCULLOCH, of San Francisco, in the United States of America,
Analytical Chemist, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE REDUCTION OF GOLD, SILVER, AND COPPER ORES," to be as
follows:-
The object of this Invention is to operate upon the ores containing gold,
silver, and copper in a more simple and economical manner than heretofore
for the purpose of obtaining the metal or metals in a metallic state. To
this end I first reduce the ore to powder by stampers or other suitable means,
and mould the same into blocks, with the addition of charcoal, sawdust, or
other vegetable refuse and a binding substance, such as clay or other plastic
material, using the same in such proportion that it will just serve to hold the
mixture together. The blocks, when moulded, I prefer to dry in open sheds

page_text: or otherwise for the purpose of solidifying the same, and I then subject them
to kiln, clamp, or oven burning after the manner of burning bricks. When
sufficiently burned, I reduce the blocks to powder, and separate the metal
either by amalgamation with mercury or by washing it out with water.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John McCulloch in the Great Seal Patent Office on the
1st September 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
McCULLOCH, of San Francisco, in the United States of America, Analytical
Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the First day of March, in the year of our Lord
One thousand eight hundred and sixty, in the twenty-third year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John McCulloch, Her special license that I, the said John McCulloch,
my executors, administrators, and assigns, or such others as I, the said
John McCulloch, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
THE REDUCTION OF GOLD, SILVER, AND COPPER ORES," upon the condition (amongst
others) that I, the said John McCulloch, by an instrument in writing
under my hand and seal, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said John McCulloch, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly. described and ascertained in and by the follow-
ing statement, that is to say:-
The object of this. Invention is to operate upon the ores containing gold,
silver, and copper, or mixtures of these ores and metals, in a more simple and
economical manner than heretofore for the purpose of obtaining the metal or
'

page_text: With
metals therefrom in a metallic or reduced state. To this end I first reduce
the ore to powder by stampers or other suitable means, and, if need be, I then
concentrate the metalliferous ingredients by separating the constituent earthy
compounds from the metallic compounds by washing and subsidence.
the ore.so prepared I intimately mix powdered charcoal, either animal or
vegetable, or any suitable substance containing carbon, such as oils and fats,
and I add thereto, if necessary, any refuse vegetable matter, such as sawdust,
dry leaves or grasses, chopped straw, or the excrementitious matter of
herbivorous animals, and this mixture I mould into such forms as will best
admit of the application of fire heat thereto for the reduction or recovery of
the metal or metals contained therein. But in order to give a sufficient
amount of consistency and resistant strength to the moulded blocks or masses
to allow of their being stacked in kilns, clamps, or ovens, and ensure their
retaining their shape while being exposed to a high temperature, I work
into this mixture a suitable proportion of clay or other equivalent binding
material, preferring clay that has been washed with water and collected by
subsidence, as that is both cheap and efficient in its action. These several
ingredients to form bricks, blocks, or cakes, I work together by the aid of a
pug mill or other suitable means, adding water as may be required to facilitate
the working. When the materials are thoroughly mixed, I mould them into
form either by means of machinery or by hand moulds, and the blocks, bricks,
or cakes thus formed I dry previously to subjecting them to artificial heat.
.
The ores upon which I propose chiefly to operate are auriferous iron and
arsenical pyrites, and the sulphides, sulphates, chlorides, carbonates, and oxides
of silver and copper. Having reduced, say, any one of these ores to powder.
and worked it into blocks in admixture with the carbonaceous and plastic
materials as above explained, I stack the blocks either in a kiln made after
the manner of a brick kiln or in a clamp or oven, preferring, however, the
former, and I then fire them as if I were burning ordinary bricks. When
sufficiently burnt, I allow the contents of the kiln, clamp, or oven, as the case
may be, to cool down; I then remove the burnt bricks or blocks, and reduce
them to powder.
The gold and silver, separately or mixed, will be found in a comminuted
metallic state scattered through the mass, while the copper may be likewise in
a metallic state, or it may be as an oxide, or a mixture of both similarly
scattered through the earthy matters of which the crushed blocks were mainly
composed, and the same may then be readily separated from the mass by
lixiviation er (in the case of gold or silver) by amalgamation with mercury.

page_text: The proportions of materials which I have found to yield good results when
manufactured into blocks, and submitted to kiln, clamp, or oven burning,
are,-
Ground ore
Charcoal
= 100 parts by weight.
25 ditto,
ditto.
Sawdust, or other vegetable matter
50
ditto, ditto.
Dry clay
-
50 ditto, ditto.
I have stated that the use of the clay is simply to hold the powdered ore
and the other matters enumerated mechanically together both while the
moulding and the burning of the blocks is being effected; and I may also
remark that the carbonaceous matters have also a mechanical use, viz., to
render the block porous, and allow of the oxygen of the air not merely to
play around, but to enter the blocks while they are under the action of the
fire. Thus, for example, when burning blocks containing sulphide of silver,
the woody and other carbonaceous matter mixed therewith will, by its partial
combustion, render the blocks porous, and thus afford a means for the oxygen
of the air to penetrate through every part of the blocks; where, meeting with
the sulphur liberated from the ore by the action of the furnace heat, it will
form sulphurous acid, and thus carry off the sulphur in a gaseous form, leaving
the silver in a metallic state imprisoned in the blocks.
As another example of the use of the charcoal and other carbonaceous
matter, I will instance the action, when combined in a block according to my
Invention, with an ore of carbonate of copper. The combustion of the woody
matter and charcoal in this case not only renders the block porous, whereby
the carbonic acid of the ore set free by the heat is allowed to escape, leaving
the metal as oxide of copper, but the carbon still present in the block by
commixture with the ground ore to a great extent takes up the oxygen from
the oxides of copper, leaving such portions of the copper in a metallic state.
It will thus be seen that the carbonaceous matters, as applied by my Invention
for the liberation of gold and the reduction and separation of silver and copper
from their ores, has a materially different and far more efficient action than
when simply applied in the manner commonly practised in the reduction of.
metals.
And further, it will be understood that as the clay acts merely as a
medium for holding the comminuted particles together, other substances
possessing the same property may doubtless be substituted for that material.
Having now set forth the nature of my Invention of "Improvements in the
Reduction of Gold, Silver, and Copper Ores," and explained the manner of
carrying the same into effect, I wish it to be understood that I do not claim.

page_text: the use of carbonaceous matters for the separation of gold and the reduction
of silver and copper from their ores irrespective of the means of applying
such carbonaceous matters, neither do I confine myself to the use of the
ingredients above mentioned for composing the blocks; but what I do claim,
under the above in part recited Letters Patent, is, subjecting the ores of gold,
silver, and copper to kiln, clamp, or oven burning when moulded or wrought
into blocks, slabs, or masses, as above described.
In witness whereof, I, the said John McCulloch, have hereunto set my
hand and seal, the Third day of August, in the year of our Lord One
thousand eight hundred and sixty.
JOHN MCCULLOCH. (L.S.)