IMPROVEMENTS IN EXTRACTING GOLD FROM ITS ORES
Year: 1855

page_text: LETTERS PATENT to Charles Low, of Bodowen, Dolgelly, North Wales,
Gentleman, for the Invention of "IMPROVEMENTS IN EXTRACTING GOLD FROM
ITS ORES."
Sealed the 31st July 1855, and dated the 21st February 1855.
PROVISIONAL SPECIFICATION left by the said Charles Low at the
Office of the Commissioners of Patents, with his Petition, on the
21st February 1855.
I, CHARLES Low, of Bodowen, Dolgelly, North Wales, Gentleman, do
hereby declare the nature of the Invention for "CERTAIN IMPROVEMENTS IN
THE EXTRACTION OF GOLD FROM ITS ORES" to be as follows:-
This Invention consists of two parts; the first, in extracting gold from its
ores by calcination of the same, and afterwards dissolving them in acid, and
precipitating the metal from the solution by means of suitable re-agents; the
second consists, after calcination, in smelting the ores in combination with
suitable fluxes.
To carry out the first part of my process, I crush the ore containing the
gold to a proper degree of fineness, either by rolls, stamps, or other suitable
crushing apparatus. I then calcine it thoroughly in a reverberatory or other
calcining furnace; I prefer a reverberatory furnace for that purpose. When
the ore is removed from the furnace, I cause water to be thrown upon it, which
disintegrates it, and likewise causes a considerable evolution of sulphurous and

page_text: other gases.
I then remove the orc into tanks prepared for the purpose, and
pour upon it a sufficient quantity of nitro-hydrochloric acid (aqua regia), in
order to dissolve the gold contained in the ore, to promote which I heat the
substances in the tank by means of a fire-place constructed for the purpose,
until the acids are in a state of ebullition, and for so long a time that it may
be considered that all the gold is taken up in solution. If any excess of acid
remains, more ore may be added, and the heat continued until the greater part
has evaporated. The mass must now be diluted with a considerable quantity of
cold water, and the whole well agitated, and afterwards allowed to subside. The
liquid solution must now be carefully drawn off into another tank prepared for
the purpose, and the residue in the first tank again washed with a small
quantity of water, and when it has subsided, to be drawn off and added to the
solution in the other tank. I then add to the solution a suitable quantity of
protosulphate of iron, or oxalic acid, or any other suitable re-agent, by either
of which the gold will be precipitated, but I prefer the use of protosulphate of
iron. The precipitation of the gold will be much accelerated by a moderate
degree of heat being applied to the solution, but this is not absolutely necessary.
The solution may now be drawn off into another tank, and the precipitated gold
reduced to a metallic state by the introduction of a little borax, and fusing it in
an ordinary wind furnace.
The second part of my process consists in smelting the ore with suitable
fluxes after calcination. I first crush the ore, calcine it, and disintegrate it by
throwing water upon it, as before mentioned. I next introduce the ore into a
reverberatory smelting furnace; a proper charge will be about one ton of ore.
I now add to it about 100 lbs. weight of fluate of lime, or hydrate of lime, or
lime in any form; if crushed small, it will be better; (that which I prefer is
fluate of lime). A sufficient degree of heat must be applied to fuse the mass.
The furnace door must now be removed, and about 100 lbs. of either lead,
litharge, or galena thrown into the furnace, together with about 50 lbs. of
scrap iron, and 20 lbs. of peroxide of manganese, and two or three shovels
full of small coal. The furnace must now be closed, and a high degree of heat
allowed to get up until the whole mass is perfectly fluid; this will generally
take about three hours more or less, according to the nature of the ore. The
furnace must now be opened, and the slags skimmed off in the ordinary way,
and the gold will be found combined with the lead, and the slags quite clean.
It will not be necessary to run off the metal at present, but another charge of
the same quantity of ore may be placed in the furnace, which should now be
well rabbled up and mixed with the melted metals below; the furnace must
now be closed, and heat applied until the whole is again in a perfectly fluid

page_text: state, having taken care to add previously as before the same quantity, 100 lbs.
of lime. I now add to it one-half the before-named quantity of flux, namely,
50 lbs. of lead, litharge, or galena; 25 lbs. of scrap iron; and 10 lbs. of peroxide
of manganese; the whole to be again heated for about three hours, and then
the slags skimmed off and another ton of ore added, repeating the same process
until four charges or tons of ore have been smelted. When the last charge
has been perfectly reduced, and the slags carefully skimmed off, the remaining
metal must be run off through the tap hole at the side of the furnace into
moulds prepared for the purpose (those which I prefer are made of iron).
The mass of metal will now be found to hold all the gold that was contained
in the ore, and it can be separated from the lead by the ordinary means used,
either by cupellation or otherwise.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles Low, in the Great Seal Patent Office on
the 21st August 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
Low, of Bodowen, Dolgelly, North Wales, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-first day of February, in the year of our
Lord One thousand eight hundred and fifty-five, in the eighteenth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Charles Low, Her special licence that I, the said Charles
Low, my executors, administrators, and assigns, or such others as I, the said
Charles Low, 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 EXTRACTION OF GOLD FROM ITS ORES," upon the condition (amongst
others) that I, the said Charles Low, 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.

page_text: NOW KNOW YE, that I, the said Charles Low, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof (that is to say) :-
This Invention consists of subjecting the matrix or ores containing gold to
the combined processes of calcining, and then fusing with lead and fluxes, as
hereafter described.
Heretofore gold has been separated from its ores or matrix by means of
washing, or by amalgamation, or by those processes combined. And I would
state, that, during a very long and extensive investigation I have found that
after these processes there remains, in all cases, a quantity of gold in the
refuse matter in a non-metallic state, or in the state of sulphuret or other
chemical combination.
I would here remark that I am aware that it has been proposed to fuse the
ore or matrix containing gold without using lead, and without first calcining
the ore, but I believe without success.
In carrying out my Invention, the ore or matrix is first broken down into
pieces, such as will pass through a sieve with meshes of a quarter of an inch.
The ore or matrix thus broken is to be introduced into a calcining furnace,
such as is used in roasting copper ores, and is to be heated to a red heat and
stirred till no evidence of sulphur is observed; then sprays or jets of water are
to be thrown over the heated ore or matrix, or steam is to be allowed to flow
up through the heated matters in jets from a perforated pipe or channel in the
bottom of the furnace, and this is to be carried on for about six hours from
the commencement of the calcining process, or in place of so introducing the
water or steam into the furnace, the calcining may be carried on for a some-
what less time, and the calcined ore or matrix drawn therefrom, and water or
steam applied during the cooling, taking care to stir the ore or matrix in such
case, in order that the vapour of water may get well in contact with all parts.
The calcined ore or matrix is then to be fused or smelted, which is most con-
veniently done in a reverberatory furnace, such as is used by copper smelters,
and this fusing or smelting I do in the following manner, and I prefer to act
on about one ton of the ore or matrix at a time, which I introduce into the
hot furnace and with it about 100 lbs. of fluate of lime. Other forms of lime
may be used, but I believe fluate of lime to be the best, and sufficient heat is
to be used to fuse the mass. The furnace door is then to be opened, and
about 100 lbs. of lead, or litharge, or galena, (preferring lead,) are to be thrown
into the furnace, together with about 50 lbs. of scrap or other iron, preferring
scrap iron, 20 lbs. of peroxide of manganese, or manganese in any other state

page_text: of oxidation, and two or three shovels full of small coal or other carbonaceous
matter. The furnace is then to be closed, and the heat raised till the whole
mass is fused, which will be found to take about three hours. The furnace
door is to be opened, and the slag is to be skimmed off, which will be found
generally free from gold, the gold having become combined with the lead. It
is not necessary to run off the metals remaining at the bottom of the furnace
at the conclusion of the first charge, but another charge of the same quantity
of roasted ore and lime may be placed in the furnace and well stirred in.
The furnace is to be closed and the heat raised till the whole is fused. I then
add only one-half the previous quantity of lead, and of the iron, and oxide
of manganese, and small coal, and again close the furnace till the whole is
fused, as before, when the furnace is to be again opened and the slag carefully
removed. In this manner may four or more charges be fused before running
off the metal, which is done through the tap hole into a mould, which I prefer
to be of iron. The gold contained in the lead may then be separated by
cupulation or otherwise, as is well understood.
I would remark, that although I have given precise quantities of the mate-
rials employed, I do not confine myself thereto, as they may be varied without
departing from my Invention; and I would have it understood that what I
claim is, the combined process herein described of calcining and fusing with
lead and fluxes the ores or matrix containing gold.
In witness whereof, I, the said Charles Low, have hereunto set my hand
and seal, this Twenty-first day of August, in the year of our Lord
One thousand eight hundred and fifty-five.
Witness,
S. CARPMAEL.
CHARLES LOW. (L.S.)