Improvements in Machinery and Appliances for Treating, Dressing, and Cleaning Tin and other Mineral Ores, and in Modes, Means, and Processes Connected therewith, and for other Useful Purposes.
Year: 1885

page_text: Improvements in Machinery and Appliances for Treating,
Dressing, and Cleaning Tin and other Mineral Ores, and
in Modes, Means, and Processes Connected therewith, and
for other Useful Purposes.
I GEORGE MIDDLETON EDWARDS of N° 54 Gresham Street in the City of
London E.C. Manufacturer do hereby declare the nature of said invention for
IMPROVEMENTS IN MACHINERY AND APPLIANCES FOR TREATING, DRESSING AND
CLEANING TIN AND OTHER MINERAL ORES AND IN MODES, MEANS AND PROCESSES
CONNECTED THEREWITH AND FOR OTHER USEFUL PURPOSES, to be as follows:-
The method generally adopted for obtaining Tin in the form and quality
commonly known as Black Tin, is to break down the Tin stone by means of
Stamps or Crushing Machines and then to dress the crushed products by means of
Rag Frames, Cleaning Frames, Round Buddles and other appliances. In association
with all of these arrangements water, and generally flowing water, is used, which
in its action separates the lighter particles which form part of the bulk of the
crushed Tin stone from the Tin, and leaves the latter more or less purified by the
process. This residuum, or Black Tin, is however well known to be generally
considerably less than might be expected to be obtained from the Tin stone, which
on careful assay or analysis is proved to contain metallic Tin in a much larger
proportion in a given quantity than is subsequently obtained by the process of
treating or dressing the Tin stone as above alluded to.
It would apparently follow that either it is not possible to obtain anything near
such good results from treating this ore in bulk, as those which are obtainable in
the Laboratory, or, that the means employed are not such as are best adapted for
arriving at a more satisfactory result.
In most cases, as above stated, flowing water is the medium employed for
separating the black tin from the aggregates with which it is associated after they
leave the crushing processes, either in the shape of rough sand or still finer sand
technically known as Tin slimes. The flow of water acts as a carrying power on
the various particles and in accordance with the principle of gravitation the
heavier particles are deposited on the surface of the Rag or Cleaning Frames and
there retained, whilst the lighter.are washed away by the scour.

page_text: But little possibility exists at present for knowing whether all or any of these
Washing Frames whilst at work, are, or are not, passing away material which
should be retained, the periodical Tin returns from the Mine or Tin Stream Works
giving generally the only intimation of the loss, the precise reason of which is
involved in doubt, and with respect to the material already treated being obviously
past elucidation.
A very slight practical investigation will convince that the separation of solid
particles of different sizes or weight, by gravitation, is best facilitated by their
deposition on the surface of a column or body of still water, of sufficient depth to
permit of the various particles immersed having time and space allowed them to
arrange themselves in the order of their respective specific gravity.
To carry out this process in perfectly still and deep water, would however be
accompanied by so many difficulties that it may be considered as impracticable for
the purpose for which it would have to be undertaken. The object of my
Invention therefore, is to make Tin dressing or saving an operation regulated by
greater exactitude in arrangement of details, and more particularly so by the
method I propose to employ for obtaining better results from the operation of the
laws of gravitation, than those which are obtained from the obviously very
imperfect manner in which this principle is at present applied.
For the purpose of my Invention therefore, I propose to make use of vessels,
constructed of wood or other suitable material, of convenient size and, advan-
tageously, cylindrical in form, of about three feet and a half deep by twenty to
twenty four inches internal diameter and open at the upper end. These Cylinders
I make use of for the purpose of receiving the Tin slimes in quantities of
about 56 lbs, more or less, at a time. The Tin slimes having been deposited
therein, either by hand labor or other means hereafter alluded to, the Cylinders
are filled nearly to the brim with water. A rod, of required length, having a
mechanical appliance fitted to its lower end calculated to disturb the water, if set
in rotatory motion, is fitted so that its lower end rests in a metal socket in the
centre of the bottom of the Cylinder, whilst its upper end is fitted with a cogged
wheel for the purpose of being set in motion by connection with a Driving Shaft,
worked by water, steam, or other power.
On this rod is a plunger of diameter of about 2 inches less than that of the
internal diameter of the Cylinder, which is fitted so as to slide up and down the
rod, which passes through its centre perpendicularly.
5
The Plunger is of sufficient depth in relation to that of the Cylinder in which
it works, as to be capable of being lowered therein to about two thirds the depth
of the Cylinder, without bringing its top to the level of the upper rim of the
Cylinder.
The purpose of this arrangement is as follows. The Tin slimes having been
placed in the Cylinder and sufficient water added, the rod, having a fan or section
of a screw propeller attached to it, is set in motion by the action of the driving
shaft, and the effect is that the water is set in rapid spiral motion upwards
and quickly carries the whole body of Tin slimes with it in an upward direction,
and so long as this motion is kept up little or no settlement of slimes will occur.
Next, in order to obtain the beneficial effect of gravitation, the rod is disconnected,
by using ordinary mechanical means such as a friction clutch or otherwise, from
the driving shaft and the screw ceasing to rotate, the water quickly loses its spiral
motion and gradually comes to a condition of comparative quiescence.
The slimes begin to be deposited on the bottom of the Cylinder immediately the
slackened motion permits, and during a period varying from two minutes to
twenty seconds of time they are permitted to be so deposited. By this time the
slimes worth saving have in sinking passed a certain depth in the Cylinder. The
plunger is then brought down by a lever or other mechanical means, into the
. Cylinder.
The effect of this operation is to displace a bulk of water equal to the cubic
contents of so much of the plunger as is immersed. The water thus displaced flows

page_text: rapidly upward over the upper edge of the Cylinder, carrying with it all the earthy
or other matter held in suspension in the water down to the level to which the
plunger descended, and leaves the slimes which had descended in the Cylinder
below that level, untouched.
For convenience of testing the value of the slimes thus expressed from the
Cylinder, a channel, sufficient to contain the water displaced by a stroke of the
plunger, is fitted outside and around the upper rim of the Cylinder for the purpose
of receiving such water, and of permitting it to be readily diverted into the
channel through which it is either to escape or be retained, as may be needful.
The plunger is then raised to its former position, the rod is connected and again
set in motion, and the slimes are either passed through an outlet then opened in
the bottom of the Cylinder or, if desirable, the action of the plunger and screw is
repeated, after more water has been each time added, until the slimes under treat-
ment are regarded as sufficiently dealt with by that particular Cylinder.
The slimes having been thus cleaned up to a certain standard, are then passed
on to another Cylinder or set of Cylinders, and a similar operation is gone through,
but after the original bulk of the slimes has been reduced by about one fourth by
the first Cylinders, it will be found necessary that a gradual reduction should be
made in the time allowed before the plunger is brought into action, as the slimes
will settle more quickly than before in consequence of the increase of their average
specific gravity.
In cases where any great bulk of slimes have to be treated, it is advantageous
that they should, in the first instance, be placed in a Cylinder in which a plunger
is not used, but the rod and screw are always kept in motion to prevent any
settlement of the slimes. These Cylinders can advantageously be of larger size
than the others, and from them the Cylinders worked with a plunger should
be fed.
After the slimes have been reduced from original bulk by about 40 p. cent,
I propose to divide them into two parts of about equal bulk, and this I propose
doing by means of a Cylinder so constructed as to be able to be divided into two
sections. The slimes having been deposited therein by hand labor or otherwise,
and the Cylinder filled with water, a rod with a screw attached is set in motion to
stir up the slimes, and, when they are well stirred, the rod and screw are with-
drawn as rapidly as possible so as to be out of the way of the slimes settling. In
about 5 minutes, more or less, the better class of slimes will be found in the lower
half of the Cylinder and the lighter in the upper half. The upper part of the
Cylinder is then moved to the right or left, by a lever or other mechanical
appliance, from above the lower part, and being fitted with a flange around its
lower end, of the same width at one side as the outer diameter of the Cylinder,
any loss of the slimes contained in it is prevented whilst it is being moved. The
slimes thus divided, at one operation, are then passed on to other Cylinders with
plungers and can be treated with reference to their respective mineral value and
to the extent necessary in each case.
"
At any stage in the above described method or process when the slimes have
been reduced sufficiently to make roasting or calcining them advantageous, that
process can be carried out and the further treatment of the roasted or calcined
slimes can be proceeded with in Cylinders with plungers, which may sometimes
advantageously be worked as separate machines the screws being set in motion by
means of a handle worked by manual labor. In placing the slimes, when nearly
completely dressed or cleaned, in kieves, for what is commonly termed "tossing
I advantageously employ means for striking the bottom of the kieve instead of the
Bides. The reason being that such gravitation as is caused by a blow is consider-
ably affected in its results, by the fact that a blow at the side gives more of
centrifugal force than gravitation, and the effect of continuous side blows is to
cause the lightest slimes to collect down the centre of the kieve in a perpendicular
column, thus in some measure spoiling the sample. In cases where this column of
light slimes may appear, owing to the necessity for side blows being delivered,

page_text: I get rid of it by passing a hollow copper or zinc cylinder or tube of the same
diameter as the column of light slimes, down the kieve, through which the said
slimes can be extracted neatly without disturbing the better class of slimes. The
extracting Cylinder I fit with thin metal guides to ensure it passing accurately
down the centre of the kieve.
The above described Cylinders, with intermittent agitation and extraction of
water and slimes, I propose to arrange systematically so as to ensure economy of
time, space and power in their working.
I also propose to use shallow settling pans or saucers in which small parcels of
tin slimes can be treated either by hand or power. These saucers being advan-
tageously made of copper or zinc having a sink or well in their centre, in which
by shaking, with the hand or otherwise, the better slimes can be made to collect.
When the water has been drained off and the slimes collected have become dry on
the surface, a brushing with a long haired but soft brush will remove the mica and
other light material which is found to cling to the Tin slimes up to the very last,
and which requires very delicate handling to remove. In all the foregoing arrange-
ments it has been intended to represent the mode of dealing with the Tin slimes as
they come from the ordinary final cleaning Frames. My Invention however affords
facilities for taking up the Tin slimes as they leave the Rag Frames, with some
advantage, or even for dealing with the Tin as it comes direct from the crushing
process.
My Invention has further for its object an improvement in the present system of
both Rag aud Cleaning Frames. For this purpose, I use Sheet Iron adequately
protected from rusting or destruction by contact with copper ore, zinc, or other
suitable metal or material in which steps have been made as shewn in Figure 8
Sheet 2 of Specification to Letters Patent granted to me dated 5th December 1882
No 5780. I place these Sheets on suitable supports made of wood or other
materials, and arrange for the Tin slimes to enter the head of the frame or sheet
which I make about 3 feet wide by about 4 feet long, more or less, and in some
cases I place the Sheets in layers with spaces between each layer, thus saving floor
space.
The action of the slimes flowing in water evenly on these frames is as follows.
On the slimes coming in contact with the first step, the upper edge of which
inclines towards the flow at an angle of about 60° from the base, they settle and
bank up until they reach as high as the step.
The water, carrying more slimes, continuing its flow, lifts in some degree the
bank of slimes formed against the step and the particles thereof immediately begin
to arrange themselves according to their specific gravity. The flow of slimes
continuing however, passes on to the next step and so in rotation until all the
steps are banked up with slime. The flow of water is then stopped to permit of so
many of these banks of slime being removed, by suitable rakes or other means, as
may from their colour or other appearance indicate that they have been sufficiently
cleaned by this process The cleaned slimes when thus taken off will be deposited
in a position suitable for transmission, either by water channels or otherwise for
being further treated in the manner already described. In thus describing the
proposed Improvements I have more particularly alluded to the treatment of Tin
ore as it is a delicate and difficult operation and requires the whole of the processes
to be employed in cleaning it, but my Invention has also for its object the washing
of finely divided ore of any description in which washing forms, or would under
the system I have described, an advantageous method of cleaning such ores. And
further, the treatment by the means indicated, of any other substances from which
.it may be desirable to carefully extract refuse by water washing.

page_text: Improvements in Machinery, and Appliances for Treating,
Dressing, and Cleaning Tin and other Mineral Ores, and
in Modes, Means, and Processes Connected therewith, and
for other Useful Purposes.
I, GEORGE MIDDLETON EDWARDS of N° 54 Gresham Street in the City of
London, E.C. Manufacturer, 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 method generally adopted for obtaining Tin in the form and quality
commonly known as Black Tin, is to break down the Tin stone by means of
Stamps or Crushing Machines and then to dress the crushed products by means of
Rag Frames, Cleaning Frames, Round Buddles and other appliances. In association
with all these arrangements water, and generally flowing water, is used, which in
its action separates the lighter particles, which form part of the bulk of the
crushed Tin stone, from the Tin and leaves the latter more or less purified by the
process.
This residuum, or Black Tin, is however well known to be generally considerably
less than might be expected to be obtained from the Tin stone, which on careful
assay or analysis is proved to contain metallic Tin in a much larger proportion in
a given quantity, than is subsequently obtained by the process of treating or
dressing the Tin Stone as above alluded to. At present very little facility exists
for determining, whether all or any of the washing Frames whilst at work are, or
are not, allowing material to pass away which should be retained, the periodical
Tin returns from the Mine or Tin stream works, giving generally the only intimation
of probable loss, the precise reason of which is involved in doubt, and with respect
to the material already treated is obviously past elucidation.
The object of my Invention therefore is to make Tin dressing or saving, more
especially in treating Tin slimes, a process regulated by greater exactitude in
arrangement of details, and more particularly so by the method I propose to
employ for obtaining better results from the operation of the laws of gravitation,
than those which are obtained from the obviously very imperfect manner in which
this principle is at present applied.
For this purpose I use washing Frames constructed of thin Sheet Iron, suitably
protected from rusting or destruction by contact with copper water, zinc or other
suitable metal or material.
These frames are formed as shewn in Figure 8, Sheet 2 of Specification to
Letters Patent granted to me dated 5th December 1882, No 5780 and in Figures I,
II and III herein.
place these Sheets in Frames, made of wood or other suitable materials and
arrange for the water carrying the Slimes to enter in even and regulated flow by
ordinary and well known methods, along the entire breadth of the head of the

page_text: Frame, which I make about 3 feet wide by 4 feet long, more or less. The result
of the slimes being thus carried in water evenly flowing upon, and over frames thus
constructed is as follows.
The frames being first filled with as much clear water as they will carry when
inclined at an elevation of about an inch to a foot from the base more or less,
the slimes on coming in contact with the edge of the water pooled or dammed back
by the first step or rise in the Frame, deposit so much of the heavier portion of the
slime as the flow of water is insufficient to carry over the impediment formed by
the. still water resisting the flow.
The portion of the slimes whose specific gravity permits of their being carried
by the flow over this first resistence, meet with a renewed impediment in the
second pool of still water dammed back by the next rise or step on the frame, and
a further deposit of the slime takes place. This process is repeated at every step
or rise on the frame until it will be found that at the lower end of the frame the
particles passing off entirely as waste are of the very lightest discription.
In every pool of water formed by the steps in the frame, it will practicably be
found that the slimes deposited differ in specific gravity from those deposited in
the other pools on the frame, and that by the process a "sizing" of atoms has
taken place in one uniform principle.
It is a well known fact that proper "sizing" of materials in dressing Tin affords
the greatest facility for separating the Black tin from its surroundings. In order
therefore to retain the advantage gained by the above described process, it follows
that the slimes thus sized should be collected in bulk according to their several
classifications, in order that they may be further subjected to treatment for
obtaining Black Tin of marketable quality. I arrange therefore that the space
between each of the steps on the Frames shall be enclosed between partitions
arranged in such a manner, that when a flow of clear water or slimes shall be
passing on to, or over, the Frames, the partitions shall be kept out of the way, as
shown in Fig. 4 herein, and that when preparation is made for clearing off the
slimes accumulated in the first pools on the frame, these partitions shall close down
on the frame at the upper end of each step or rise on the frame, as shown in Fig. V
herein. The method of cleaning the frame I pursue is, by ordinary mechanical
means, to elevate one side of the frame about 2 feet more or less, and pass a current
or flush of clear water through each of the channels formed by the partitions when
closed. The water is arranged to be let in by any of the ordinary and well known
methods, and made to work automatically if required or deemed advantageous.
As however it is important that the pool or pools at the head of the frame should
not be allowed to get more than about two thirds filled with slime deposit, it is
advantageous that the frames should be personally attended to, and also that the
cleansing with clear water should be continued as long as may be apparently needed.
The slimes thus cleared off the frames are allowed to flow into Channels or launders
running underneath the frames and so arranged as to keep such slimes according
to such classifications as may be desired with referance to their future treatment.
I further propose to use Cylinders of wood, metal, or other suitable material of
about 2 to 3 feet high, more or less, and from 10 to 18 inches internal diameter,
more or less, into which slimes shall be conducted by water flowing through a pipe
or funnel inserted into the Cylinders so that the delivery of slimes shall be at a
level about rds down the column of clear water with which the Cylinder is filled
on commencing operations. The effect is that the up current, when the water in
the Cylinder begins to overflow over its upper edge, carries with it the lighter
particles, and leaves the heavier in the bottom of the Cylinder, thus effecting a
further "sizing" without the risk of loss of Tin attendant on washing with
a horizontal flow of water.
These Cylinders as shown in Fig. 7 herein, I propose to arrange systematically,
the flow and overflow being dealt with by ordinary and well understood methods,
and a tap being placed in the bottom or side of the Cylinder för the purpose of
washing them free from deposite.

page_text: For the purpose of my Invention I also propose to make use of vessels, con-
structed of wood or other suitable materials of convenient size, and, advantageously,
cylindrical in form, of about three feet and a half deep by twenty to twentyfour
inches internal diameter and open at the upper end.
These Cylinders I make use of for the purpose of receiving the Tin slimes in
quantities of about 56 lbs, more or less, at a time.
The Tin slimes having been deposited therein, either by hand labor or other
means, the Cylinders are filled nearly to the brim with water.
A rod, of required length having a mechanical appliance fitted to its lower end
calculated to disturb the water if set in rotatory motion, is fitted so that its lower
end rests in a metal socket in the centre of the bottom of the Cylinder, whilst its
upper end is fitted with a cogged wheel for the purpose of being set in motion by
connection with a driving shaft worked by water, steam or other power.
On this rod is a plunger of diameter of about 2 inches less than that of the
internal diameter of the Cylinder, which is fitted so as to slide up and down the
rod, which passes through its centre, perpendicularly.
The plunger is of sufficient depth in relation to that of the Cylinder in which it
works, as to be capable of being lowered therein to about two thirds the depth of
the Cylinder, without bringing its top to the level of the upper rim of the Cylinder.
The purpose of this arrangement is as follows-The Tin slimes having been
placed in the Cylinder, and sufficient water added, the rod, having a fan or section
of a screw propeller attached to it, is set in motion by the action of the driving
shaft (in cases where power other than hand is used) and the effect is that the
water is set in rapid spiral motion upwards and quickly carries the whole body of
Tin slimes with it in an upward direction, and as long as this motion is kept up,
little or no settlement of slimes will occur. Next, in order to obtain the beneficial
effect of gravitation the rod is disconnected, by using ordinary mechanical means,
such as a friction clutch or otherwise, from the driving shaft and, the screw
ceasing to rotate the water quickly loses its spiral motion and gradually comes to
a condition of quiescence.
The slimes begin to be deposited on the bottom of the Cylinder immediately the
slackened motion permits, and during a period of a few minutes, varying according
to the quality of slimes dealt with, they are permitted to be so deposited.
By this time the slimes most worth saving have in sinking passed a certain depth
in the Cylinder. The plunger is then brought down by a lever, or other mechanical
means, into the Cylinder.
The effect of this operation is to displace a bulk of water equal to the cubic
contents of so much of the plunger as is immersed.
The water thus displaced flows rapidly upwards over the upper edge of the
Cylinder, carrying with it all the earthy or other matter held in suspension in the
water down to the level to which the plunger descended, and leaves the slimes
which had descended in the Cylinder below that level untouched.
For convenience of testing the value of the slimes thus expressed from the
Cylinder, a channel, sufficient to carry off the water displaced by a stroke of the
plunger is fitted outside and around the upper rim of the Cylinder, for the purpose
of receiving such water, and of permitting it to be readily diverted into the channel
through which it is either to escape or be retained, as may be needful.
The plunger is then raised to its former position the rod is connected, and again
set in motion, and the slimes are either passed through an outlet then opened in
the bottom of the Cylinder, or, if desirable, the action of the plunger and screw is
repeated, after more clear water has been each time added, until the slimes under
treatment are regarded as sufficiently dealt with by that particular Cylinder.
The slimes having been thus cleaned up to a certain standard, are then passed on
to another Cylinder or set of Cylinders, and a similar operation is gone through,
but after the original bulk of the slimes has been reduced by about one fourth
more or less by. treatment by the first Cylinders, it will be found necessary that
gradual reduction should be made in the time allowed before the plunger is brought

page_text: into action, as the slimes will settle more quickly than before, in consequence of
the increase of their average specific gravity.
After the slimes have been reduced from original bulk by about 40 p. cent, more
or less, I propose to divide them into two parts of about equal bulk, and this
I propose doing by means of a Cylinder so constructed as to be able to be divided
into two sections.
Whilst the slimes are being deposited therein by hand labor or otherwise and the
Cylinder filled with water, a rod with a screw attached is set in motion to stir up
the slimes, and when they are well stirred the rod and screw are withdrawn as
rapidly as possible so as to be out of the way of the slimes settling.
In about 5 minutes, more or less, the heavier class of slimes will be found in the
lower part of the Cylinder and the lighter in the upper part. The upper part of
the Cylinder is then moved to the right or left, by a lever or other mechanical
appliance, from above the lower part and being fitted with a flange around its
lower end, of the same width at one side as the outer diameter of the Cylinder,
any loss of the slimes contained in it is prevented whilst it is being moved. See
Fig. 6. herein.
The slimes thus divided, at one operation, are then treated with reference to
their respective mineral value and to the extent necessary in each case.
At any stage in the above described method or process when the slimes have been
reduced sufficiently to render roasting or calcining them practical and advantageous,
that process can be carried out and the further treatment of the roasted or calcined
slimes can be proceeded with in Cylinders, with plungers, which may generally,
advantageously, be worked as separate Machines the screws being set in motion by
means of a handle worked by manual labor as shown in Fig. 8 herein.
In thus describing the proposed Improvements I have more particularly alluded
to the treatment of Tin ore in slimes, and as they come from treatment by the
ordinary Rag frames, but my Invention has also for its object the washing of finely
divided ore of any description in which washing forms, or would form under the
system I have described, an advantageous method of cleaning such ore from refuse
or waste, and further the treatment by the means and methods indicated of any
other substances from which it may be desirable to carefully extract refuse by water
washing.
Now in order that my improvements may be clearly understood and readily
carried into practice, I will proceed to illustrate the same by and describe the
drawings hereto annexed.
Fig. I is a section of the sheet metal bent in the manner I propose for forming
frames. The steps being about 1 inch high and placed about 5 inches apart.
Fig. II is a cross-section of a frame A being the metal and B. B the wooden
sides, the edges of the metal lie in a groove formed in the wood and the groove
is then filled up with asphalte or other suitable material, to make a watertight
joint.
Fig. III is a perspective view of a frame thus constructed, the frame being placed
at a suitable angle with the horizontal, the slimes run down in the direction shewn
by the arrow in Fig. I.
Fig. IV shows the arrangement I use for cleaning off the deposits that are lodged
on the frame
Over the upper end of each step is a board, C, these boards are carried by pivots
supported by the brackets E, E, E, screwed to the wooden sides of the frame and
can all be moved simultaneously by the rod D, in a way resembling a venetian
blind,.
1, while the washing is going on, the boards are kept in the position shewn in
Fig. IV, so as not to cause any obstruction, but when the deposits are to be taken
off they are turned into the position shewn in Fig. V, and one side of the frame is
raised and a sufficient quantity of clear water turned on to carry the deposits out
over the other side, the deposits falling into a series of troughs or launders, so s
not to become mixed again.

page_text: Fig. VI shews a section of the split kieve or Cylinder, the top part F, can be moved
along the table H carrying its contents from above the bottom part, I, of the kieve,
until it is over the discharging hole J, through which they fall, the tail board, G,
attached to F covers I as the top is moved along and prevents the weight of the
slimes in F forcing those out of I while the movement is going on.
Fig. VII shows a cylinder with a funnel delivery, the tube from the funnel
going about two thirds down the cylinder.
Fig. VIII she ws the washing machine. It is a cylindrical tub in which the
slimes, with a sufficient quantity of water, are placed. O, is a square shaft carrying
the agitator, P, at the bottom of the tub, which may advantageously be formed
like a screw propeller, the cylindrical plunger N, the diameter of which is a little
less than the inside diameter of the tub, has square bushes at top and bottom
which will allow it to move up and down the shaft, but not to turn without
turning the shaft also, the horizontal shaft, R, has a handle at the outer end, and
on the inner end a cast iron disc, and this shaft can be pushed in as shewn in the
drawing to bring the 'disc under the bottom of the plunger or drawn back so as to
allow the plunger to be lowered into the tub. When the bandle is turned the
disc causes the plunger to turn by the friction and the agitator P at the bottom of
the tub is revolved. After this has been done for a short time the turning is
stopped and a short interval allowed for the heavier particles to descend to the
lower part of the tub, and then before the lighter slimes have settled, the plunger
is lowered into the tub by the lever S so as to descend about half way down the
tub causing the displaced water and the lighter slimes that are in suspension, to
flow over into the annular space T, from which they are run out. The plunger is
then raised and the tub filled up with water and the process repeated.
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 as my Invention is
The general combination and arrangements substantially as hereinbefore specified
and shewn in the Drawings herewith.
Dated this twenty third day of February in the year of our Lord one thousand
eight hundred and eighty six,