Improvements relating to the Extraction of Precious Metals from their Ores.
Year: 1898

page_text: Improvements relating to the Extraction of Precious Metals from
their Ores.
"We, FRANK BOULTON ASPINALL, of 25, Dacre Park, Lee, Kent, Electrical
Engineer, and EDOUARD CHRISTOPHER EKSTRÖMER, of 56, Wellesley Road, Snares-
brook, Essex, Electrical Engineer, do hereby declare the nature of this invention
to be as follows:
-
The present invention has reference to what is known as the amalgamation
process, wherein the gold or other ores are submitted to the action of mercury, for
the extraction of the precious metal therefrom.
Our object is mainly to ensure the recovery of a larger percentage of precious
metal from the ore than has hitherto been accomplished, and incidentally to effect
an economy in the mercury, and to avoid some of the drawbacks attending its
present use.
According to our invention, the ore, finely crushed, is first fed into a closed
cylindrical casing provided with a suitable relief valve, which casing is arranged
vertically, & has a rotating vertical shaft mounted centrally therein.
This shaft carries a number of circular trays, which rotate therewith, & which
are divided concentrically into annular troughs. Into these troughs dip one or
more sets of ploughs, which, as the trays rotate, throw the ore from trough to
trough, and finally over the edge of the tray. Between the trays are set funnel
shaped plates, which catch the ore thus falling from the tray above, and direct it
into the middle of the tray below.
Into the casing at the points where the ore is stirred by the ploughs above men-
tioned, is introduced vapour of mercury, which is driven or drawn in by a blast of
air, and caused to impinge upon the ore when in a state of agitation, thereby
ensuring the efficient amalgamation of the precious metal. Instead of rotating the
trays, we may rotate the ploughs, keeping the trays still, to accomplish the same
end.
In this part of the apparatus, which which we call the amalgamating chamber,
there may be any desired number of rotating trays, for instance, three or four,
& a corresponding number of sets of ploughs & mercury-injecting nozzles. Beneath
the lowest tray, the casing is contracted into a narrow neck, provided with a damper
slide and a screw conveyor. The damper remains closed until a quantity of
amalgamated ore accumulates sufficient to form a seal. The damper is opened,
& the amalgamated ore is fed by the conveyor into a chamber, which we call the
concentrating chamber. Here the ore falls upon rotating dishes, which, by centri-
fugal action, pass the ore from one dish to another placed below, until a discharge
shoot is reached. In this chamber, no fresh mercury is introduced, but the ore
already amalgamated is concentrated prior to separation, which takes place in the
following manner:

page_text: From the concentrator the ore falls into a casing containing a deep basin or
basins, into which basins project the nozzles of an air blast.
These nozzles are so arranged and mounted on a central hollow shaft, that they
can be rapidly rotated as the air blast is delivered into the basin containing the
ore.
The effect of this blast is to blow the lighter particles of the ore out of the basin
while the heavier substance, viz., the amalgamated precious metal, remains behind
for removal at convenient intervals.
The separating of the ore may be effected in a single basin, but two or more
basins, one over the other, each provided with a rotating ring of air blast nozzles,
may be employed, if desired.
Instead of separating the ore according to this dry method, which however we
consider most desirable, the separation may be effected, if preferred, by washing
with water after the ore has passed the amalgamating and concentrating chambers
above described.
Dated this 15th day of February 1898.
NEWTON & SON,
Agents for the Applicants.
Improvements relating to the Extraction of Precious Metals from
their Ores.
We, FRANK BOULTON ASPINALL, of 25, Dacre Park, Lee, Kent, Electrical
Engineer, and EDOUARD CHRISTOPHER EKSTRÖMER, of 56, Wellesley Road, Snares-
brook, Essex, Electrical Engineer, 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:-
The present invention relates to the extraction of the precious metals from their
ores by what is known, broadly, as amalgamation, that is to say, the crushed ore
is submitted to the action of mercury, which lays hold of, or amalgamates with the
precious metals, and thus separates them from the ore.
The object of the invention is mainly to ensure the recovery of a larger percent-
age of precious metals from the ore than has hitherto been accomplished, and
incidentally to effect an economy in the mercury employed, and to avoid some of
the drawbacks attending its present use.
The invention, therefore, consists in the mode of obtaining the contact between
the mercury and the crushed ore, whereby the above named objects are effected.
To this end, the ore to be treated is ground to an almost impalpable powder, and
it is subjected to the action of fumes of mercury in a closed vessel.
In carrying out the invention, the mercury fumes are produced in any con-
venient manner, so that oxidation of the mercury will not take place, and these
fumes are brought into contact with a cloud of the pulverized ore, which cloud will
be produced in any convenient manner, and thus the mercury and ore will com-
mingle, and the mercury readily lay hold of, and amalgamate with, the precious
metals. The amalgam is then separated from the ore by a blowing operation,
and the recovery of the precious metals is effected in any convenient manner. By
this means, the extraction is effected in a dry state.
The mercury fumes may be injected by a pressure of air into a vessel in which
the cloud of ore is produced, or the powdered ore may be injected into a vessel
containing the mercury fumes.

page_text: For the purposes of the invention, an apparatus which is shewn in the accom-
panying drawings, has been devised, and this apparatus will now be described.
Fig. 1 is a vertical section of an apparatus employed for extracting the precious
metals from their ores.
Fig. 2 is an elevation, partly in section, of the additional plant employed for
the purpose of the invention.
Fig. 3 is a plan view, on an enlarged scale, of an apparatus which is termed
a plough.
Fig. 4 is an elevation of one side of this plough; and
Fig. 5 is a similar view of the other side of the plough.
A, Fig. 2, is a furnace for heating the mercury contained in the vessel A¹
(shewn in dotted lines) to obtain the fumes above mentioned. B is a compressed
air reservoir, into which air is driven by a force pump or equivalent contrivance, C,
through the pipe C¹. From the reservoir B, the air is passed by the pipe B¹ to the
mercury chamber A', and by a pipe 132 to a separator, which will be presently
described.
From the chamber A¹, the mercury-laden air passes by pipes D, D1, D2, to an
amalgamator E, which will now be described.
These pipes are provided with cocks, so that one or more of the pipes may be
temporarily cut off, if required.
This apparatus consists of a cylindrical casing E, having a hopper-shaped
bottom E, and a cover E³, carrying a feeding hopper F, all made of iron, which
does not become "wetted" by the mercury.
This apparatus is so formed that the inlet and outlet will become sealed by the
powdered ore, so that the fumes will not escape.
Below the amalgamator, E, is another vessel G, which is termed a concentrator,
which is also composed of iron, and is capable of being sealed, as before explained,
and from this vessel the material passes by a spout to the separator before men-
tioned.
Passing vertically and centrally through the amalgamator E, the hopper F, and
concentrator G, is a spindle H, which is supported and driven in any convenient
manner. The spindle H carries two screws H', which serve to regulate the flow
of material from the hoppers F and E¹.
Upon the spindle is mounted a series of trays J, and each tray is provided with
partitions J, preferably vertical and concentric, so as to form a central space 1,
with two annular concentric passages or troughs 2, 3, round it.
The edge of the tray is provided with an upwardly extending conical lip or
flange J
These trays J are contained in compartments formed in the casing by inverted
conical partitions K, and to the underside of these partitions K, and of the cover n³,
are secured conical deflectors K¹, of the same diameter as the lips or flanges ]
of the trays J, and arranged so that there will be a small space between. the edges
of the flanges and the deflectors.
Below each deflector, is a perforated annular pipe D, in connection with one
of the pipes D, D', or 13, by means of which the mercury-laden air is thrown
on the lip or flange J2 of the tray J beneath, for a purpose to be presently
explained.
Dipping into the troughs of each tray is a peculiarly shaped appliance, which
is designated a plough, L, and is shown at Figs. 3, 4, and 5.
In Fig. 1 the position of these ploughs L is indicated, though the ploughs are
not shown, from want of space, but in Fig. 3 the plough is shewn, drawn on an
enlarged scale, as applied to the tray J, the cover of the plough being removed,
to show more readily the internal construction of the appliance.
This plough, then, consists of a casting L, having three passages, 1*, 2*, 3*,
one for the central space 1, and one for each trough, 2, 3.
The bottom of each passage commences low down, say, at the bottom of the space
or trough, and then rises so as to pass over the top of the partitions J. At this
point, in the case of passages 1*, 2*, there is a well or spout, L¹, projecting down-

page_text: wards into the trough 2, or 3, as the case may be, and, in the case of passage 3*,
an opening L2 is made in the side wall delivering on to the lip or flange Je of the
tray J. The walls of the passages, and the wells or spouts L', are curved to corre-
spond with the partitions J, and the partitions, as they revolve, pass partly between
and partly under the passages, as will be seen from the drawing.
In the mouth of each passage is a nozzle M, which is in connection with one of
the pipes D, D1, D2, so that jets of the mercury, laden air are injected into the
mouth of the passages.
The action of this part of the apparatus is as follows: The ground ore is placed
in the hopper F, and is gradually fed by the screw H¹ into the central space 1
of the top tray J. The spindle H being driven at considerable speed, the tray is
rotated therewith, and the material is thus forced up the passage 1*, or is scooped
up by the plough, which projects into the space. This, so to speak, raises a cloud
of dust in the passage, with which the mercury fumes issuing from the nozzle M
come in contact.
The dust and amalgam then fall by the well or shoot L¹ into trough 2, where
the same operation takes place in passage 2*. The dust and amalgam then fall
into trough 3, and the same operation takes place in passage 3*. From this pas-
sage, the dust and amalgam pass by the opening L on to the lip or flange J2 of
the tray, up which they gradually creep by centrifugal action, and fall over the
edge.
On the lip or flange, the ground ore is subject to the action of jets of mercury
fumes coming from the annular pipes D* above mentioned.
The ore, with the amalgam, then slides down the conical partition K, which
practically forms a hopper, into the central space 1 of the next tray J, being
assisted, if desired, by brushes set at an angle, and attached to the underside of
the tray above.
The same series of operations as above described will then take place with respect
to the second tray J, and this may be continued any number of times, according to
the nature of the ore to be treated and the number of trays provided.
The partitions J¹ of the trays J may be curled over at the top inwards, and the
ploughs may be arranged to underlie these curled over edges, with the mouth close
to the walls; the object of this is to render the ground ore, which by centrifugal
action will be caused to move outwards towards the partitions, and creep up the
same, less likely to pass away without coming into contact with the mercury.
From the last tray J, the whole mass falls into the hopper E, by which it is
conducted to the concentrator G. It is allowed to enter in regulated quantities
by the screw H', or by any other regulating device.
E is an outlet pipe in connection with each compartment of the amalgamator E,
by which the air under compression may escape from the casing. As however,
mercury fumes may pass away with the air, the pipe E* dips into an interceptor E*1
containing water, in which the fumes are condensed and retained. The inlets
to the branches of E* will be covered with gauze, to prevent the dust passing
away with the air and fumes.
The concentrator consists of a cylindrical casing G with two, three, or more
transverse conical partitions G¹ (practically forming hoppers), and the compart-
ments formed by these partitions enclose dishes G2, mounted on the shaft H, and
rotating with it at considerable speed.
The mercury, which will have become condensed in the shape of small globules,
before it passes to the concentrator, will, as with the ore it creeps outwards by
centrifugal action, and is, so to speak, rolled over and over, form blobs or large
globules of amalgam, and thus it becomes as it were concentrated. This action
may be continued for such number of times as may be thought desirable, and the
concentrated ore then passes to the separator P, Fig. 2.
This separator consists of a cylindrical casing P, having a trunk P¹ at its lower
end leading to the open air or elsewhere, as may be desired. On the cover of the
casing is secured a hopper P³, which receives the ore and amalgam from the con-

page_text: centrator G, and inside the cover is an inverted conical deflector P3. Running
vertically and centrally through the apparatus is a hollow spindle Q, which receives
air from the reservoir B, and is rotated in any convenient manner.
The feed from the hopper P2 is regulated by a screw Q on the spindle Q, or in
any other convenient manner.
Below the deflector P3 is a pan R, having an overhanging rim or flange, as
shewn, and this pan is supported and arranged in any convenient manner, so that
it may be readily removed when required. The spindle Q descends nearly to the
bottom of this pan, and, at the end, is provided with hollow arms, which serve to
distribute compressed air in the pan, and also to stir up the contents.
The concentrated ore is allowed to fall into this pan, and, by the action of the
blast, the dust is blown away, and drops down outside the pan into the trunk, from
which a screw conveys it away.
The overhanging lip or flange prevents the amalgam from passing away with
the dust.
From time to time, the amalgam is removed from the pan, and is treated in
any convenient manner to recover the precious metals.
It will be understood that the apparatus described is capable of more or less
modification in many respects, in the shape of mechanical equivalents, for carrying
out the process; an essential feature of which is to separate the particles of the
ore, to produce a cloud of dust, with which the fumes of mercury are brought into
contact, and we therefore do not intend to confine ourselves to the exact details
shown.
Having now particularly described and ascertained the nature of our said in-
vention and in what manner the same is to be performed, we declare that what we
claim is:-
1. The process for extracting precious metals from their ores, consisting in
producing a cloud of powdered ore, and subjecting the same to the action of fumes
of mercury, as and for the purpose set forth.
2. The process for extracting precious metals from their ores, as herein described,
consisting in producing a cloud of powdered ore, subjecting the same to the action
of fumes of mercury, condensing the mercury fumes which are holding the precious
metals in the form of amalgam, and blowing the ore dust from the same, as set
forth.
3. The process for extracting precious metals from their ores as herein described,
consisting in grinding the ore to an almost impalpable powder, raising the powder
in the form of a cloud, subjecting the same to the action of fumes of mercury,
condensing the mercury fumes which are holding the precious metals in the form
of amalgam, concentrating the amalgam, and then blowing the ore dust from the
same, as set forth.
4. An apparatus for use in the process for extracting precious metals from their
ores, consisting of an amalgamator having devices to raise the powdered ore in
the form of a cloud, and means for injecting fumes of mercury thereinto, and a
separator having means for removing the dust from the amalgam by blowing, as
herein set forth.
5. An apparatus for use in the process for extracting metals from their ores,
and consisting of an amalgamator having means for producing a cloud of powdered
ore, and means for injecting fumes of mercury thereinto, a concentrator in which
the mercury is collected in, or concentrated into, the form of blobs or large globules
of amalgam, and a separator having means for blowing away the dust, as set
forth.
6. An apparatus for use in the process for extracting metals from their ores,
and consisting of an amalgamator having rotary devices for carrying the powdered
ore, stationary devices dipping into the moving ore, and adapted to produce a cloud
of ore, and means for injecting mercury into the cloud, as and for the purpose set
forth.

page_text: 7. Apparatus for extracting precious metals from their ores, consisting of an
air compressor, means for producing fumes of mercury, an amalgamator in which
the ore in the form of a cloud of dust is subjected to the action of the mercury,
a concentrator for concentrating the mercury, and a separator all combined and
operating as herein shewn and described.
Dated this 14th day of November 1898.