Improvements in the Extraction of Precious Metals from Ores.
Year: 1891

page_text: Date of Application, 15th Apr., 1891
Complete Specification Left, 13th Jan., 1892-Accepted, 26th Mar., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Extraction of Precious Metals from Ores.
WILLIAM THOMPSON RICKARD of 201 Stanstead Road, Forest Hill in the
County of Kent, Chemist and Metallurgist do hereby declare the nature of this
invention to be as follows:-
My invention consists in improvements in certain methods of dry or furnace
metallurgy, together with mercurial amalgamation by which the extraction of
precious metals from their ores is rendered less expensive and effects a saving of
time and loss in residues.
The improvements are effected
1st. By the use when necessary as in the case of ores containing rebellious
elements of an ordinary brick reverberatory furnace constructed with one or more
hearths as may be required and which is fed with the pulverized ore containing
sulphur or other volatile constituents or rebellious elements from a hopper in which
there is a screw or other arrangement which regulates the quantity of ore to be
passed into the furnace and admitted through a pipe, more or less vertical which
may be enclosed in the brickwork so as to deliver the pulverized ore into the
throat of the furnace through an elongated horizontal pipe or orifice where it falls
over the mouth of another similar opening or pipe discharging a blast of hot air
uncontaminated by the products of combustion having passed through red hot iron
pipes prior to its introduction and which on impinging on a bosh causes the ignited
ore to be scattered throughout the entire furnace which is to be kept at a
temperature of 1000° Fhr. more or less by means of the ordinary fireplace.
The blast of hot air as before describel is forced into the furnace through the
iron pipes by any kind of blower, and by its force keeps the ore in motion without
the aid of rakes, thus presenting continually fresh surfaces to be acted on by the
pure oxygen of the injected air, on its passage through the furnace and the attached
dust chambers, in the direction of the chimney.
2nd. The ore being now in a condition for mercurial treatment, (by the removal
of its refractory constituents) is introduced into a vessel or tank of iron, (having a
Scinicircular bottem, flat ends and sides, firmly bolted to a strong timber foundation)
in which revolves an horizontal shaft, to which are attached iron plates or dises.
Enough water is added to bring the mass into a thin pulp, which is heated by
team to 180° Fhr. after agitating by means of the revolving iron plates. Mercury
is then introduced in the form of a soluble or acid sulphate (supplemented by a
little ordinary mercury) in proportion to the ascertained contents of gold or silver
in the ore, which is reduced to its native condition by contact with the iron of the
vessel (and being in a very minute state of division) is very rapidly disseminated
through the entire mass of the ore, where it amalgamates with the gold or silver,
which are entirely removed from their matrix. After half an hour's brisk agitation
of the revolving plates, the speed is reduced, a stream of cold water laid on, washing
off the tailings and allowing the amalgam to fall to the bottom, from whence it i
removed and treated in the ordinary manner.
3rd. The precipitation or settling of the amalgam, during the washing off of the
limes and failings, is facilitated and time gained, by transferring the contents of
the amalgamator to a similar vessel (having amalgamated copper plates or discs
instead of iron in which the settling is done, while a fresh charge is being operated
on in the amalgamator.
The amalgamated copper plates gather up and secure much of the finer particles
of amalgam which might otherwise escape in careless or too rapid washing.
Dated this Fourteenth day of April 1891.

page_text: COMPLETE SPECIFICATION.
Improvements in the Extraction of Precious Metals from Ores.
WILLIAM THOMPSON RICKARD formerly of 201 Stanstead Road, Forest
Hill in the County of Kent, but now of 136 Maygrove Road, West Hampstead in
the County of Middlesex, Chemist and Metallurgist, 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 has reference to improvements in the treatment of metallic ores.
for the purpose of extracting gold or silver or both therefrom in a more economical
manner and in a less time than has heretofore been usual.
For this purpose the ore containing gold or silver or both is, after being reduced
to a finely divided state, agitated or stirred in a solution of a soluble or acid
sulphate of mercury by means of iron stirrers within a vessel that can also
advantageously be made of or contain metallic iron. By this means the mercury in
the sulphate of mercury is reduced to the metallic state, and being intimately mixed
with the ore, forms an amalgam even with the finest particles of gold or silver or
both therein, and thereby ensuring the extraction of practically the whole of the
gold or silver. When the ore consists wholly or mainly of a metallic sulphide or
sulphides, as for example iron pyrites, it may, after being finely pulverized, be
directly treated in the manner set forth, for removing the precious metal or metals
therefrom by amalgamation. When however the ore contains small quantities of
rebellious elements as for examples lead, antimony, copper and arsenic, it is
advantageous to first remove or oxidize such elements by subjecting the finely
divided ore to a roasting operation. This can advantageously be done in a
furnace of the construction illustrated in Figs. 1, 2 and 3 of the accompanying
drawings,
Fig. 1 being a side elevation,
Fig. 2 a central section and
Fig. 3 a horizontal section.
This furnace is constructed with a number of superposed hearths 1, and with a
fire grate 2 at one end of the lowerinost hearth. In communication with the space
above the uppermost hearth are a number of settling chambers 3 the entrance and
exit to and from which are alternately at top and bottom so as to impart a
zig-zag course to the hot gases, vapour and finely divided ore in suspension
passing therethrough.
The pulverized ore containing the rebellious elements is fed into this furnace
from a hopper 4 in which there is means such as a screw 5 for regulating the
quantity of ore supplied, which is admitted to the furnace through a pipe 6 which
may be enclosed in the brickwork as shewn so as to deliver the pulverized
ore into the throat of the furnace through an elongated horizontal pipe or
orifice 6 whence it falls over the mouth of another pipe 7 through which a blast
of hot air is discharged, the arrangement being such that the ore is caused by the
blast to impinge against the bosh or cnd 12 of one of the hearths in such a manner
as to be scattered, and thence carried by the gaseous current through the furnace
which is kept at a suitable temperature, say of about 10. 0 Fhr., by means of a
fire on the fire grate 2. By this means the ore is kept in motion without the aid
of rakes, and is effectually oxidized by the oxygen in the hot air blast.
The hearths are each formed with an opening 1 through which ore settling on
them can be discharge into a truck placed below the lowermost hearth.
The blast of hot air may be produced by forcing air, by a suitable blower such
as a centrifugal fan, through the pipes 7 embedded in the brickwork of the furnace
so as to be heated thereby. Or the air may be heated by being passed through a
hot blast stove of ordinary construction as well understood.
Figs. 4 and 5 are respectively a plan and end view of amalgamating apparatus

page_text: suitable for treating the unroasted or roasted ore, or auriferous slimes, as the case
may be, in the manner hereinbefore mentioned for the extraction of the gold.or
silver or both therein.
Fig. 6 is a vertical section on the line Fig. 4.
This apparatus or amalgamator comprises a fixed tank 8 of iron having a semi-
circular bottom and within which is arranged a rotary shaft 9 to which are fixed
a number of iron dises or plates 10 arranged at an angle to the axis of the shaft as
shewn. Into this tank the finely divided ore or auriferous slime, in a dry or wet
state, is placed, and sufficient water is added to bring the mass to a thin pulp,
which, after being agitated by revolving the plates 10, may advantageously be
heated by injection of steam, to a temperature of say about 180° F. A solution
of soluble or acid sulphate of mercury is then gradually added to the pulp and
intimately mixed therewith by rotating the iron discs 10. The soluble sulphate
of mercury used can be prepared by boiling mercury in an excess of sulphuric
acid until the whole of the mercury is converted in a white crystalline powder:
any excess of sulphuric acid can be removed by decantation or otherwise. The
crystalline powder thus obtained is an acid sulphate of mercury soluble in water.
A small quantity of metallic mercury may also he added with advantage to the
pulp. A suitable proportion of sulphate of mercury to use is such that there shall
be six to eight parts by weight of mercury in the salt to each part by weight of
gold or silver present in the pulp and determined by a previous analysis. The
mass is briskly stirred by rotating the discs 10 for about thirty minutes at say
about thirty to forty revolutions per minute. The diameter of the iron discs 10 being
say about 3 feet. The speed of rotation is then reduced to say about ten to fifteen
revolutions per minute, and a stream of cold water is introduced into the tank so
as to wash off the tailings which flow off by one or other of a series of outlet
nozzles 11 in one side of the tank, and allow the gold or silver amalgam or gold
and silver amalgam to fall to the bottom of the tank from whence it is removed
and treated in the ordinary manner for the recovery of the precious metal or
metals therefrom.
By the method described the sulphate of mercury is brought into intimate
contact with the precious metal or metals in the ore, and by contact with the iron
of the stirrers and tank or with iron in other form as scrap iron &c. placed in the
tank, which may then be of wood, is reduced to finely divided metallic mercury,
which forms an amalgam with the precious metal or metals present, and
sulphate of iron which passes imo solution. Furthermore by the use of acid
sulphate of mercury, hydrogen is liberated, which being a powerfully reducing
agent assists in effecting the extraction of the precious metal or metals.
The precipitation or settling of the amalgam during the washing off of the
slimes and tailings can be facilitated and time gained by transferring the contents
of the amalgamator to another vessel which may be similar to that shewn in
Figs. 4, and 6 but provided with plates or discs of amalgamated copper, instead
of iron, and in which the settling and recovery of the amalgam is effected, while a
fresh charge is being operated upon in the amalgamator. The amalgamated
copper plates serve to gather up and secure much of the finer particle- of amalgam
which might otherwise escape by careless or too rapid washing. To keep the
copper plates amalgamated, they are arranged to dip into mercury placed in
the bottom of the settler. The lime and tailings passing off from the settler
may flow over an inclined riffle covered with sheet copper and provided with
mercury traps as well understood for the purpose of recovering any amalgam that
may be present therein.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what |
claim is:
The herein described improved method of extracting gold or silver, or both.
hom ores, including slime, by agitating the ore whilst in a finely divided state, in a

page_text: solution of soluble or acid sulphate of mercury by means of iron stirrers or in the
presence of metallic iron as set forth.
Dated this 12th day of January 1892.
W. Lloyd Wise,
W. 1. KICKARD.
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.