An Improved Method of Working, Preparing, and Concentrating Auriferous Alluvium.
Year: 1889

page_text: Date of Application, 31st July, 1889
Complete Specification Left, 30th Apr., 1890-Accepted, 4th Oct., 1890
PROVISIONAL SPECIFICATION.
An Improved Method of Working, Preparing, and Concentrating
Auriferous Alluvium.
I, EDMOND GUILLEMIN-TARAYRE. of 23, Boulevard de Strasbourg, Paris, in the
Republic of France, Mining Engineer, do hereby declare the nature of this invention
to be as follows:-
My invention relates to a method of working, preparing and concentrating
auriferous alluvium, in which the water-channels intended for the operation by
utilizing the mechanical action of the water under pressure are provided with certain
means of distribution, sorting concentration and preparation which are efficacious and
simple in their action and therefore applicable for use in countries of small com-
mercial resources.
The supply channels which bring the water are kept filled during the intervals
between the workings through the employment of sluice-doors, the movement of
which is very rapid and efficacious.
This sluice-door is of trapezoidal form and of similar section to the channel, it is
fixed to a vertical spindle and has formed on it a nut to which a screw-thread imparts
an upward or downward movement to cause it to quit or enter grooves made in
the stone work. These sluice-doors are placed at intervals of two hundred metres.
The action of the hydraulic jet under pressure upon the auriferous earth is caused
by means of a hydraulic-nozzle, consisting of a conical nozzle-head having a swivel
joint, fixed on the inclined end of a tube supplying the water under a pressure
varying from 50 to 100 m.
The nozzle is counteweighted by a weight suspended to the flange of the joint and
by another weight arranged between the two working arms.
Slightly in advance of the hydraulic nozzle L erect a compressed air-receiver, for
the purpose of avoiding the ram-shocks on the one hand, and the drawing along of
the air which interrupts the mechanical energy of the jet of water on the other
hand; this receiver is provided with an automatic float-valve allowing the expulsion
of the air in excess and retaining a constant volume of compressed air in the
receiver.
A pressure-gauge serves to indicate the pressure and the variations in the level of
the water in the inlet vessel of the system of pipes; this allows of regulating the
flow at an almost constant height. Lateral sluices or valves placed on the lower
reservoir allow of the manipulation. A bottom cock serves to blow out the deposits
which may accumulate in the pipe during periods of rest.
The alluvium disaggregated by the action of the water is drawn along first over
gratings formed of convexed rails, placed at- certain distances apart so as only to
admit the lower fragments of gravel of a dimension which will enter the washing
channels placed beneath.
These wasbing channels are formed of large blocks of quartz at the place where the
erection is permanent; they are of wood and consequently removable where the
water acts.
The substances which arrive with the current of water in the washing channels,
meet at the bottom of those provided with longitudinal concentrating gratings formed
of convexed rails. Under the said gratings are placed wooden collecting frames
formed in three compartments which are provided with vertical partitions made of
strips of suitable material, bent at the two ends at a right angle, and screwed to the
two sides of the frame. This arrangement extends for a distance of 50 to the head
of the washing channel in which are deposited the nuggets and grains of gold with
the larger part of the heavy sand. Metallic gratings rest on cross-pieces and this

page_text: arrangement allows the heavy materials to be deposited and concentrated under the
gratings by the action of the current through the channel.
The current then passes under a more inclined grating formed of angular hars
which facilitates the passage through the grating of the heavier and finer particles,
which fall into a bath of mercury; they then pass under gratings and over a
partitioned trough which serves to retain the amalgam-molecules: the current then
reaches other gratings and collecting frames and thence passes through channels with
iron gratings arranged on supports.
At the end of this arrangement of gratings are placed the cavities for separating
the sand. These cavities which are placed in pairs in the washing stream serve for
sorting and concentrating heavy sand and gravel from the size of a cubic millimetre
to a cubic centimetre. Each group consists of two troughs provided with a piston,
to which an alternate movement is communicated by means of a hydraulic motor
which actuates a single piston for each two stamping troughs. Three of the sides of
the troughs are inclined at an angle of 45 degrees and the fourth or outer side is
vertical and wide open towards the compartment of the trough. They are surmounted
by two perforated sheet iron-plates; the holes in the lower plate being rather larger
than those in the upper plate: there is a space beween the two plates, which space is
half filled with a bed of sand or gravel so coarse that it will not pass through the
holes; these materials are selected from amongst those of the same kind which it is
proposed to separate. The materials, thus separated, and so to speak, filtered
between the two perforated plates and the gravel bed fall into the compartment of
the trough in which the piston works whence they are easily extracted.
When the said materials consist of sand, a continuous current of water is turned on
by means of a sluice, which water carries along the sand, which is again concentrated
on sleeping-tables provided with canvas.
If they consist of gravel they are discharged by frames into deposit-compartments,
from which the water is drained off.
At the end of this length of channel is placed an inclined discharge grating by
means of which the materials, of which the dimensions exceed the width apart of the
rails, are conveyed into waggons for their removal. The remainder passes through
the grating and falls onto an inclined plane into a pit whence the current carries it
along into another channel provided with gratings on supports, which channel
receives the discharged waters from the hereinbefore described troughs.
At the end of this channel are a series of troughs for separating the materials,
which are rather coarser than the preceding.
An iron grating is placed at the top of the inclined discharge-grating, and is
movable upon a
hinge, so that by raising or lowering it the current can be caused to
pass underneath or above the discharge-grating together with the materials which are
drifted along with it.
After the second series of troughs, the current has another fall over the second
separating-grating and passes over another bath of mercury; then it passes across a
series of gratings, with oblique supports beneath them serving to guide the heavy
slime towards the lateral-gratings whence they fall on a slightly inclined sleeping-
table, formed of a concrete base furnished with a layer of cement. The current
which escapes from this sleeping-table passes through a small channel over a mercury-
washer, it then escapes through a pipe extending into the pit of the second discharge-
grating.
The second discharge-grating is similar to the first, with a movable grating at
the top and intermediate gratings with smaller intervals between the bars so as to
allow the fragments to escape exceeding fifteen millimeters in size. These discharged
materials are received at the bottom of the grating in sorting tunnels in three or
six piles, each of which piles, in passing onto piston-sieves or onto other sorting
apparatuses of well known or suitable construction, such as the washing-apparatus
of Max Evrard, causes an enrichment over the lower part of the washing bed which
is separated by reason of the mechanical treatment; the rest is thrown onto the
waste-heap.

page_text: The same operation is repeated at certain distances, at a third and fourth discharge-
grating, upon fragments more and more reduced, which in turn are sorted with regard
to size, and their yield concentrated by exterior mechanical washings whilst the
richest materials continue to be concentrated and separated in the troughs of the
washing channel. After the fourth grating the current of materials carried along is
admitted, in the order of increasing sizes, through lateral gratings provided for this
purpose, and fall onto a large sleeping-table, formed of cemented concrete, at the
outlet of which the current spreading out more and more runs over a bath of mercury
formed of a double transverse trench, surmounted horizontally by two sheets of
amalgamated copper with transversely undulating surfaces for the purpose of fixing
the last traces of powder susceptible of being amalgamated.
A discharge of the sand takes place at this point and is effected through the
medium of an Archimedean screw operated by hydraulic power in a continuous
manner.
The current charged with argillaceous earth and fine saud then enters clarifying.
vessels in order to deliver clear water to the river.
The length of the active part of the washing stream is 550 metres and that of the
purifying vessels and discharge channels 750 metres.
The collection of the rich materials which are deposited on the iron gratings is
ensured by a double set of channels, the washing being effected on one side and the
collection on the other.
The channels in which are deposited the nuggets of gold and the grains of amalgam
are placed in tunnels and easily rendered inaccessible.
In the uncovered channels which follow the first discharge grating only sand and
gravel, more or less concentrated by long washing, is deposited on the gratings. In
order to collect them as often as may be considered necessary, they are discharged in
a most simple manner by a flooding with water; for this purpose the movable
discharge-gratings are raised so as to render the current continuous. From one
end to the other of the washing works the gratings are raised by their lower end,
they are set upon the two crutches or supports with which their upper part is provided
and they thus allow the current of water to remove what was deposited underneath
them without it being necessary to completely remove them; they are supported
by cross-pieces placed transversely between the tops of the two walls of the
channel.
The materials carried along are sorted and concentrated on their passage over the
troughs; they can be delivered onto any discharge-grating and over the exterior
sorting apparatuses, or, if they are sufficiently rich, they can be carried along into a
large depositing vessel which is opened to receive them in front of the fourth grating.
The materials are thus delivered ready to hand in the works either by the current
itself or by railroads from the sorting apparatuses.
In the metallurgical preparing works, the sand and the gravel are conducted to a
distributor which furnishes each stamping-mill with the required quantity according
to its capacity.
The grating for the passage of the slime formed of wire gauze fixed in iron
frames opening around the inner side, may have greater or smaller inclines according
to the requirements of the varying nature of the materials to be ground. The
admission of water into the troughs of the mill is effected through the interior and
if required through the exterior across the grating. The mill may grind in a dry
state but in this case a suction fan ensures the removal of the ground materials.
For grinding with water, the sand is triturated in presence of a small quantity of
mercury proportionate to the yield of the sand. The materials, amalgamated or not,
which escape are carried along by the water, at first over the discharge end of the
grating, formed of a sheet of amalgamated copper where the progress of the
operation can be tested, and then over an inclined sleeping-table, provided with
canvas of a variable length, according to the nature of the rock being treated.
The current then passes over a distributing-board and flows over a second inclined

page_text: sleeping-table covered with flannel, it then passes to two mercury baths followed by
perpendicular partitions hefore being directed towards the clarifying sump.
The heavy sand which is collected on the various flannel cloths are then passed
either into the stamping-mill or into amalgamating tubes or vats.
The amalgamating operation is terminated in 5 hours by adding a quantity of
mercury ten times stronger than the weight of the gold to be collected.
An admission of water into the trough in movement, allows of the union of the
mercury, after which the charge is run off into washing vats.
The water is poured into the vat by an upper cock, whilst on the other hand, the
materials of the amalgamating vat are run into it. An agitator gives the movement
to the mass of water and places the slime in suspension, the lighter parts of which
can flow off at three different open levels successively through a single door; the
heaviest parts, amalgam-globules and dense materials become deposited on the
bottom where the passage of iron rakes fixed to the lower part of the agitators
keeps them continually in suspension so as to facilitate the union with the mercury,
which, assisted by the slope, runs little by little into the circular channel.
The bottom plate inclines slightly outwards which causes the amalgam to flow
towards the opening of the mercury-box serving to collect it.
When proceeding to collect the amalgam, the mercury is received in a carriage
which transports it to the laboratory, the contents are poured into the laboratory-vat,
in which the washing of the amalgam may be effected before placing it in the
filters.
The slime of the washing-vat is deposited in the sump with that of the stamping-
mills, and the clarified water enters the works, whence it is taken by pumps to be
reused for grinding and washing purposes.
Dated the 31st day of July 1889.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
An Improved Method of Working, Preparing, and Concentrating
Auriferous Alluvium.
I, EDMOND GUILLEMIN-TARAYRE, of 23, Boulevard de Strasbourg, Paris, in the
Republic of France, Mining Engineer, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed to be particularly described
and ascertained in and by the following statement :-
My invention relates to a method of working, preparing and concentrating
auriferous alluvium, in which the water-channels intended for the operation by
utilizing the mechanical action of the water under pressure are provided with certain
means of distribution, sorting, concentration and preparation which are efficacious
and simple in their action and therefore applicable for use in countries of small
commercial resources.
In the accompanying drawing
Figure 1, is a general view of the whole arrangement.
The supply channels which conduct the water are kept filled during the intervals
between the workings through the employment of sluice-doors, the movement of
which is very rapid and efficacious.
Each sluice-door (shown in detail in Figure 2) is of trapezoidal form and of
similar section to the channel, it is fixed to a vertical spindle a and has formed on
it a nut b to which a screw-thread c imparts an upward or downward movement
to cause it to quit or enter grooves d made in the stone work. These sluice-doors
are placed at intervals of two hundred metres.
The action of the hydraulic jet under pressure upon the auriferous earth is caused
by means of a hydraulic-nozzle (shown detached in elevation at Figure 3 Sheet 1)

page_text: consisting of a conical nozzle-head L having a swivel joint, fixed on the inclined.
end A of a tube B supplying the water under a pressure varying from 50 to 100.
The nozzle is counterweighted by a weight p suspended to the flange of the joint
and by another weight arranged between the two working arms.
The large water nozzles are usually of that kind which are 200 millimetres in
diameter with swivel-joints and delivering 500 litres per minute, the delivery being
modified on the other hand by nozzles having openings of various sizes.
Smaller water nozzles (Figures 12 and 13) mounted on movable frames serve for
auxiliary operations; they are joined onto the tubes of a derivation channel of
100 diameter and are in every respect similar to the large water nozzles. The
most useful kinds are those of 50 to 75 millimetres in diameter and having swivel
joints.
Slightly in advance of the hydraulic nozzle at about 10 metres I erect a compressed!
air-receiver C (shewn in section at Figure 4) for the purpose of avoiding the ram-
shocks on the one hand and the drawing along of the air which interrupts the
mechanical energy of the jet of water on the other hand; this receiver is provided
with an automatic float-valve e allowing the expulsion of the air in excess and
retaining a constant volume of compressed air in the receiver.
A pressure-gauge m serves to indicate the pressure and the variations in the level!
of the water in the inlet vessel of the system of pipes, this allows of regulating the
flow at an almost constant height. Lateral sluices or valves D D (the box of which
is shewn in section at Figure 5) placed on the lower reservoir allow of the manipula-
tion. A bottom cock serves to blow out the deposits which may accumulate in the.
pipe during periods of rest.
Figure 6 is a plan of the air-receiver and of the pipe connections.
The alluvium disaggregated by the action of the water is drawn along first over
gratings formed of headed rails, placed at 40 m apart so as only to admit small
fragments of gravel which enter the washing channels placed beneath.
These washing channels F are formed of large blocks of quartz at the place where
the erection is permanent; they are of wood and consequently removable where the
water acts.
The channels are 0.70m in width and depth, their inclination is 45m per metre.
The substances which arrive with the current of water in the washing channels,.
meet the bottom of these provided with longitudinal concentrating gratings or riffles
formed of headed rails of 3 metres in length. These gratings E (Figure 1, and
shown detached in detail at Figures 7, 8 and 9) are connected at the middle by three
bolts g provided with collars which serve to keep them 25 m apart. Under the
gratings E are placed wooden collecting frames F one of which is shewn detached at.
Figure 11 formed of au oak frame composed of two longitudinal bars 40 x 60"/m in.
height connected by four cross pieces of the same dimensions. The three compart-
ments of the frame are provided with vertical partitions g¹ placed at 25 / apart and
made of strips bent at the two ends at a right angle, and screwed to the two sides of
the frame. This arrangement (shewn in Figure 1) exists for a distance of 50 metres
and extends from the washing channel in which are deposited the nuggets and grains
of gold with the larger part of the heavy sand. Then follow metallic gratings
resting on cross-pieces of oak at their two ends; this arrangement exists for a
distance of 100 metres in length so as to allow the heavy materials to be deposited
and concentrated under the gratings by the action of the current through the
channel.
The current then passes over a more inclined grating G (Figures 9 and 10) formed
of angular bars 20m square and placed at a distance apart of 2m. The current
here falls with a first descent of 0.20 which facilitates the passage through the
grating of the heavier and finer particles, which fall into a bath of mercury H;
they then pass under gratings and over a partitioned trough which serves to retain
the molecules of amalgam: the current then reaches other gratings and collecting
frames for a distance of 50 metres, then follow 100 metres of channel with iron
gratings arranged on supports.

page_text: At the end of this arrangement of gratings are placed the cavities for separating
the sand Figure 15. These cavities X, X which are placed in pairs in the washing
stream serve for sorting and concentrating heavy sand and gravel from the size of a
cubic millimetre to a cubic centimetre. Each group consists of two troughs U pro-
vided with a piston U, to which an alternate movement is communicate the extent
of which movement is limited to suit the size of the assorted material the oscillating
movement being obtained by means of a hydraulic motor which actuates a single
piston for each two separators or classifiers. The troughs are each 1 metre in length
by 0-70 in width and three of their sides are inclined at an angle of 45 degrees
and the fourth or outer side is vertical and wide open towards the compartment of the
trough. They are surmounted by two perforated sheet-iron plates V, VI, the holes in
the lower plate being rather larger than those in the upper plate: there is a space
of 8m between the two plates, which space is half filled with a bed of sand or gravel
of regular coarseness and so coarse that it will not pass through the holes; these
materials are selected from amongst those of the same kind which it is proposed to
separate. The materials, thus separated, and so to speak, filtered between the two
perforated plates and the gravel bed, fall into the compartment of the trough in which
the piston works whence they are easily extracted.
When the said materials consist of sand, a continuous current of water is turned
on by means of a sluice, which water carries along the sand, which is again con-
centrated on sleeping-tables provided with canvas.
If they consist of gravel they are discharged by frames into deposit-compartments,
from which the water is drained off.
At the end of this length of channel (see the detail Figure 14) is placed an inclined
discharge grating J formed of rails placed 25" apart and inclined at an angle of
30° to the horizontal. The materials, the dimensions of which exceed the width
apart of the rails are conveyed into waggons for their removal. The remainder passes
through the grating and falls onto an inclined plane M into a pit P whence the
current carries it along into another channel 50 metres in length provided with
gratings on supports which channel receives the discharged waters from the preceding
troughs.
At the end of this channel are a series of troughs for separating the materials,
which are rather coarser than the preceding.
The end of the first section preceding the discharge-grating is formed with an
iron grating movable upon a hinge and placed at the top of the inclined grating so
that by raising or lowering this grating N the current can be caused to pass under-
neath or above the discharge-grating together with the materials which are drifted
along with it.
After the second series of troughs, the current has another fall of 0.20m over the
second separating-grating and passes over another bath of mercury; then it passes
across a series of gratings with oblique supports beneath them serving to guide the
heavy slime towards the lateral gratings whence they fall on a slightly inclined (5%)
sleeping-table, formed of a concrete base furnished with a layer of cement.
The
current which escapes from this sleeping-table passes through a small channel over a
mercury washer; it then escapes through a pipe extending into the pit of the second
discharge-grating.
The second discharge-grating is similar to the first with a movable grating at the
top and intermediate gratings with smaller intervals between the bars so as to allow
the fragments to escape exceeding fifteen millimetres in size. These discharged
materials are received at the bottom of the grating in sorting tunnels in three or six
piles, each of which piles in passing on to piston sieves or on to other sorting
apparatuses of well known or suitable construction, such as the washing-apparatns of
Max Evrard, causes an enrichment over the lower part of the washing bed which is
separated by reason of the mechanical treatment; the rest is thrown onto the waste-
heap.
The same operation is repeated at distances of about 50 metres, at a third and
fourth discharge-grating upon fragments more and more reduced, which in turn are

page_text: sorted with regard to size, and their yield concentrated by exterior mechanical
washings whilst the richest materials continue to be concentrated and separated in
the troughs of the washing channel. After the fourth grating the current of
materials carried along is admitted, in the order of increasing sizes, through lateral-
gratings provided for this purpose, and fall onto a spacious sleeping-table, formed of
cemented concrete at the outlet of which the current spreading out more and more
runs for 2 metres in width over a bath of mercury formed of a double transverse
trench, surmounted horizontally by two sheets of amalgamated copper with trans-
versely undulating surfaces for the purpose of fixing the last traces of powder
susceptible of being amalgamated.
A discharge of the sand takes place at this point and is effected through the
medium of an Archimedean screw operated by hydraulic power in a continuous
manner.
The current charged with argillaceous earth and fine sand then enters settling tanks
in order to deliver clear water to the river.
The length of the active part of the washing stream is 550 metres and that of the
purifying vessels and discharge channels 750 metres.
The collection of the rich materials which are deposited on the iron gratings is
ensured by a double set of channels, the washing being effected on one side and the
collection on the other.
The channels in which are deposited the nuggets of gold and the grains of amalgam
are placed in tunnels and easily rendered inaccessible.
In the uncovered channels which follow the first discharge-grating only sand and
gravel. more or less concentrated by long washing, is deposited on the gratings. In
order to collect them as often as may be considered necessary, they are discharged in
a most simple manner by a flooding with water; for this purpose the movable
discharge-gratings are raised so as to render the current continuous. From one end
to the other of the washing works the gratings are raised by their lower end, they
are set upon the two crutches or supports with which their upper part is provided
and they thus allow the current of water to remove what was deposited underneath
them without it being necessary to completely remove them; they are supported by
cross-pieces placed transversely between the tops of the two walls of the channel.
The materials carried along are sorted and concentrated on their passage over the
troughs; they can be delivered onto any discharge-grating and over the exterior
sorting apparatuses or if they are sufficiently rich they can be carried along into a
large depositing vessel O (Figure 1 Sheet 1) which is opened to receive them in front
of the fourth grating. The materials are thus delivered ready to hand in the works
either by the current itself or by railroads from the sorting apparatuses.
In the metallurgical preparing works, the sand and the gravel are conducted to a
distributor which furnishes each stamping-mill with the required quantity according
to its capacity. The stamping-mill is of the Californian type with quadrantal cams
of a radius equal to the distance of the axes of the stamps and of the driving-shaft
this giving a curve which is the most advantageous for raising the tails or projections
of the stamps by gyratory rolling.
The grating for the passage of the slime formed of wire gauze fixed in iron frames
opening around the inner side, may have greater or smaller inclines according to the
requirements of the varying nature of the materials to be ground. The admission of
water into the troughs of the mill is effected through the interior and if required
through the exterior across the grating. The mill may grind in a dry state but in
this case a suction fan ensures the removal of the ground materials.
For grinding with water, the sand is triturate! in presence of a small quantity of
mercury proportionate to the yield of the san:. The inaterials amalgamated or not,
which escape are carried along by the water. at first over the discharge end of the
grating, formed of a sheet of amalgamated copper, where the progress of the operation
can be tested, and then over a sleeping-table regulated to a 7% incline and provided
with canvas (see the detail Figure 16) of a variable length, according to the nature of
the rock being treated, but which should not be less than two metres 50 in length.

page_text: The current then passes over a distributing-board R and flows over a second sleeping-
able S of To slope, covered with flannel, it then passes to two mercury baths xx
followed by perpendicular partitions y before being directed towards the clarifying
sump T.
The heavy sand which is collected on the various flannel cloths are then passed
either into the stamping-mill or into amalgamating tubs or vats.
The amalgamating operation is terminated in 5 hours by adding a quantity of
mercury ten times the weight of the gold to be collected.
An admission of water into the trough in movement, allows of the union of the
mercury, after which the charge is run off into washing vats.
The water is poured into the vat by an upper cock, whilst on the other hand, the
materials of the amalgamating vat are run into it. An agitator gives the movement
to the mass of water and places the slime in suspension, the lighter parts of which can
flow off at three different open levels successively through a single door; the heaviest
parts, amalgam-globules and dense materials become deposited on the bottom where
the passage of iron rakes fixed to the lower part of the agitators keeps them con-
tinually in suspension so as to facilitate the union with the mercury, which, assisted
by the slope, runs little by little into the circular channel.
The bottom plate inclines slightly outwards which causes the amalgam to flow
towards the opening of the mercury-box serving to collect it.
When proceeding to collect the amalgam, the mercury is received in a carriage
which transports it to the laboratory, the contents are poured into the laboratory-vat
in which the washing of the amalgam may be effected before placing it in the filters.
The slime of the washing-vat is deposited in the sump with that of the stamping
mills and the clarified water enters the works, whence it is taken by pumps to be
re-used for grinding and washing purposes.
Figure 17 is a diagrammatic view shewing the path of the materials during their
treatment.
The materials which are carried along with the current of water into the washing
channels are composed of all kinds of soil from the finest sand to large stones of
several pounds weight. The object to be attained by my invention is to effect the
concentration and isolation of the rich or useful elements and the elimination of
the useless or sterile parts.
In the first part of the washing apparatus A, B, C, D the current is subjected to
violent agitation owing to the presence of a quantity of fragments whereby only the
heavier particles are allowed to settle such as gold in grains and all minerals of great
-density such as platina, grains of lead, sulphuret of lead, oxide of tin, specular iron,
diamonds and generally all elements which are of a density from three to four times
greater than water. They are deposited through the metal gratings in the compart-
ments of the collecting frames placed beneath. Gold in visible particles being the
heaviest is deposited in the first twenty five metres.
If it is desired to effect this separation in a continuous manner without interrupting
the washing current filtering troughs are placed along the bed of the current by means
of which the deposits are distributed directly upon sleeping tables, arranged laterally
to the cleansing stream and provided with flannels, more or less inclined according to
the nature of the soil treated.
Gold in a state of impalpable powder carried along by the current is collected at
-various points.
1. At the middle of the first washing channel by the passage of the current over a
fine grating inclined over a chamber provided with a mercury bath C.
2. By filtering troughs having perforated plates placed in front of the first discharge
grating at D.
The deposit is effected in a continuous manner by the running off of the muddy
waters over sleeping tables covered with flannel; at the same time the gold is deposited
in fine grains of about the size of a millimetre.
3. At E, another derived current carries the heavy muddy sediment first over a
sleeping table thence over a bath of mercury.

page_text: The first discharge grating, the bars of which are placed at about 20 millimetres
apart, rejects all the elements of greater size which fall into waggons and are discharged
at F.
Beneath the discharge grating of No. 1, the current is divided into two by a second
grating the openings of which are of about 8 millimetres in size.
The upper current which is that of the larger elements is directed over the
grating No. 2 which rejects all the particles of a larger size than 8 millimetres whilst
the current of the smaller elements continues its course by first passing over filtering
troughs provided with plates having perforations of about 2 at G to separate the
grains of heavy sand from 1 to 2 millimetres in diameter; the current then passes into
a channel where perforated lateral plates allow the heavy fine sands to pass and which
can remain as impalpable gold in the muddy waters at E.
This derived current falls upon a sleeping table where it deposits the heavy sand
and then passes over a bath of mercury before continuing its course under the auxiliary
grating No. 2, the openings of which are 4 millimetres wide, which receives with
the current derived from the grating No. 1, the elements of from 2 to 8% in size
which it separates into two parts, rejecting in the trommels the elements of
from 4 to 8m, and allowing fragments less than 4mm in size to pass at H.
The first trommel is formed with sheet metal plates provided with holes of 5
and 6" in diameter and a second trommel is. provided with openings of 7
and 8 millimetres in diameter whereby there results a sifting into four piles of 5, 6,
7 and 8 millimetres diameter respectively, which are passed separately to a washing
apparatus I (system Max Evrard) which enriches them from two to three times by
throwing out two thirds to the waste heaps and by separating the other third, which is
placed in trucks and conveyed to the amalgamating works.
The current having escaped from the second auxiliary grating, passes over a series
of troughs or sieves provided with openings 3" in diameter which remove from the
current the richest fragments of this size.
The derived current rejoins at K the current escaping from the 2nd discharge
grating and the whole is received upon a 3rd discharge grating the openings of which
are 4 apart and which removes everything of greater diameter. The current then
passes over filtering troughs or sieves having plates with openings of 4" in diameter
for the separation of useful material of this size at L, and passes over the 4th grating,
the openings of which are only about two millimetres in size. All that passes this is
placed in trucks and conveyed to the waste heaps. On issuing from this 4th discharge
grating the sandy elements which the current still contains are very poor and nearly
useless; but in order to obtain if possible further useful fragments therefrom, the
current is received upon a large sleeping table M of 4 breadth by 40" long at the
end of which is an Archimedean screw N which moves in a channel perpendicular to
the table in order to expel the sediment. The richest parts of the sand remain on the
sleeping table from which they are removed by scrapers.
The remaining sand which has escaped to the Archimedean screw and been carried
along by the current of water is deposited in a well from which it is extracted by a
chain pump O to be loaded into trucks; the current passes from this well by an over-
flow into a discharge canal to which it conveys only very fine sand mixed with
earth.
These materials then pass between amalgamated copper plates in order to collect any
traces of gold or of amalgam which might be carried along; the current finally arrives
in settling chambers (6 in number) provided with valves on their lower surfaces
through which the mud or sediment is withdrawn and afterwards serves for irrigating
purposes whilst the clear water escapes from the last settling chamber and returns to
the river by a discharge canal.
The sand and gravel deposited between A and B under the gratings are composed
of rich ores which are separated and utilized after the separation of the gold in grains;
the materials deposited from B to C and from C to D and even so far as K are similarly
concentrated as an ore and are sent directly to the works, for which purpose it is
sufficient to raise the gratings, open all the movable sluices of the discharge gratings
B

page_text: and direct a stream of water therein which reunites them in the chamber P, near the
amalgamating works.
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 combined method of working, preparing and concentrating by continuous
mechanical washing, auriferous alluvium substantially as herein before described with
reference to the accompanying drawings.
Dated the 30th day of April 1890.
G. F. REDFERN & Co.,
4 South Street, Finsbury, London, Agents for the Applicant