Year: 1887

page_text: Date of Application, 24th Nov., 1887
Complete Left, 29th May, 1888
Complete Accepted, 29th June, 1888
I JOHN BERGER SPENCE of 31, Lombard Street, in the City of London, Merchant
do hereby declare the nature of this invention to be as follows:-
The object of this invention is to extract the gold from ores containing the same in
a more perfect and economical manner than heretofore, and the invention consists in
the use of perchloride of iron with or without the addition of common salt, to dissolve
out the gold.
In carrying out my invention, the ore, which has been crushed to a fine powder, is
placed in a vessel or tank so arranged that it may be heated and provided with means
to agitate the mass. A quantity of perchloride of iron, with or without the admixture
of common salt, both in solution, is added to the ore, and the temperature of the
vessel is raised to about 160 to 200 degrees Fahrenheit.
When the ore contains large quantities of sulphur arsenic, and also oxide of iron
or sulphides, I prefer to calcine the ore before treating it with the perchloride of
iron.
The effect of calcining will be to drive off the sulphur arsenic &c., and the remaining
material will largely consist of oxide of iron containing gold. Now if this material
be placed in the tank or vessel, and Hydrochloric acid be added thereto, and the
temperature raised to from 160° to 200°, the oxide will be converted into perchloride
of iron, which will dissolve the gold.
The action of the perchloride of iron under heat, whether the natural ore containing
Sulphides or the calcined ore is being treated, is to dissolve the gold and retain it in
solution as chloride of gold.

page_text: The liquor is then run into tanks, and the gold is precipitated by means of proto-
sulphate of iron, or by any other well known means.
The tanks for digesting the ore (which in its crushed state is very fine and slimy,
and is thus apt to arrest the percolation or straining of the liquor), I prefer to make
with a false bottom of wire gauze, upon which is placed coarse sand. A pendent
draw off pipe is provided from the space below the gauze, with a bend or turn in it,
to prevent the upward passage of air.
By means of this arrangement a partial vacuum may be obtained below the gauze,
and thereby the liquid from above may be caused to pass off more freely from the ore
precipitated on the coarse sand.
Dated this 24th day of November 1887

page_text: Purpose of Extracting the Gold therefrom.
I JOHN BERGER SPENCE of 31 Lombard Street in the City of London, Merchant,
do hereby declare the nature of this invention and in what manner the same is
to be performed, to be particularly described and ascertained in and by the following
statement:-
This invention relates to an improved mode of treating auriferous ores for the
extraction of gold therefrom, the object being to effect an economy in the process.
In carrying out my invention, I first reduce the ore to a fine powder, and place the
same in a vessel or tank so arranged that it may be heated, and I provide means for
agitating the contents of the tank.
To the crushed auriferous ore admitted to the tank, I add a solution of commercial
perchloride of iron, with or without the admixture of common salt, and in quantity
sufficient to cover the ore. The temperature of the contents of the tank I then raise
to from about 160°-200° Fabr., agitating the mixture during the heating, and
preferably by the injection of steain into the tank, which will be constructed of wood.
I prefer to use a fairly strong solution of the perchloride of iron of about
sp. gr. 1. 150 (30 Twad.), and this solution I saturate with common salt, when the ore
to be treated contains an appreciable amount of silver.
The action of the commercial perchloride of iron, under heat, is to dissolve the
gold, and retain it in solution as chloride of gold.
The liquor is now run into tanks, and the gold is precipitated by means of proto-
sulphate of iron, or by any other well known means.
The tank or tanks for digesting the ore (which, in its crushed state, is very fine and
slimy, and is therefore apt to arrest the percolation or straining of the liquor), I prefer
to fit with a false bottom of wicker work, or perforated wood, for the reception of a
filter bed of coarse sand, composed first of a layer of fine sand, then of a layer of
coarse sand, and finally of pebbles, covering the whole with laths; or perforated wood,
to prevent disturbance of the bed.-Below the false bottom, the tank is fitted with a
pendent draw-off pipe, which is trapped by a bend or turn to prevent the upward
passage of air. By means of this arrangement, a partial vacuum may be obtained
below the filter bed, and thereby the liquid from above may be caused to pass off more
freely from the ore precipitated on the filter.
When the auriferous ore to be treated is found to contain large percentages of
sulphur and arsenic, and also oxide of iron or sulphides, I prefer to calcine the ore
before treating it with the perchloride of iron.-The effect of calcining will be to
drive off the sulphur, arsenic &c., and the remaining material will largely consist of
oxide of iron containing gold. Now, if this calcined material, after crushing, is

page_text: placed in the tank or vessel, and hydrochloric acid be added thereto, and the tempera-
ture raised to 160 to 200 degrees, the oxide will be converted into perchloride of iron,
which will dissolve the gold, retaining it in solution (as above explained) as chloride
of gold.
Having now particularly described and ascertained the nature of my said!
invention and in what manner the same is to be performed, I declare that what
I claim is :-
The treatment of auriferous ores with perchloride of iron in the manner and for
the purpose above set forth.