Improvements in or relating to the Treatment of Ores with Solvents.
Year: 1897

page_text: Date of Application, 23rd Feb., 1897-Accepted, 19th Feb., 1898
COMPLETE SPECIFICATION.
Improvements in or relating to the Treatment of Ores with Solvents.
We, WILLIAM ADOLPH KONEMAN, Civil and Mining Engineer, and WILLIAM
HENRY HARTLEY, Gentleman, both of 432, Strand, in the County of Middlesex, do
hereby declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
This invention relates to metallurgical operations and apparatus for the purpose
of overcoming certain physical difficulties in the hydro-metallurgical treatment of
ores for the extraction of the precious metals therefrom. It is a well known fact,
that, in order to extract metals from their ores by means of solutions which have
solvent power for the metal or metals to be extracted, the common practice is to
cause such solutions to percolate or filter through the ore by gravitation, the solutions
after percolation escaping through a porous filter bottom. Such treatment can
be successfully carried on only, if the physical condition of the ore is such, as to
leave it in a porous or minutely interstitial condition, and in order to create such
a condition, it becomes necessary in almost all instances, to separate from the
granular ore particles all accompanying atomic matter, which is commonly termed
Slimes, and which is either natural or has been reduced to a slimy condition, that
is to say, a non-granular condition during the process of pulverization. The
removal of this slimy matter is first of all a great expense and it also causes a very
large loss of the metal or metals to be extracted, as it is a well-known fact that in
almost all instances these slimes are richer in the metals to be extracted than the
original ore; for example in the Transvaal gold extracting establishments it is
found that the slimes amount to from 15 to 25% of the original ore bulk, and that
even after such slimes have been subjected to amalgamation treatment for the
purpose of extracting the gold therefrom, they still contain an amount of gold
averaging not less than 4 dwts. per ton, and the total amount of gold so lost in the
slimes is estimated at 14 million pounds sterling per annum. We have mentioned
these facts to draw attention to the main features of advantage in our invention,
which may be said to consist of:-
1st. Obviating the necessity of removing the slimes from the ore.
2nd. Making the treatment absolutely independent of the physical condition
of the ore, that is to say, it is immaterial how much slimes, talc or clay the ore
contains for successful treatment.
3rd. The more perfect extraction of gold, particularly in that last residual
portion of solution which is retained by the ore in the shape of final moisture after
the application of a wash water.
4th. The treatment of the ore by a considerably reduced amount of solution.
5th. The avoidance of loss of chemicals owing to continuous surface oxidation
during filtration.
6th. The automatic discharge of the tailings in only a slightly moist state and
all avoidance of shovelling and manual manipulation.
To accomplish the above-named objects we employ an apparatus which by easy
manual manipulation operates in a manner to successfully accomplish the main

page_text: principle discovered by us, viz.: that when a slime-containing ore is mixed with
a solution, and is placed in a receptacle, which, when suitably closed can be subjected
to a high air pressure, that under the action of such pressure the separation of the
slimes and ore from the solution takes place rapidly and in such manner, that the
slime containing-ore is compacted in the bottom portion of such receptacle to a
degree of high density, and that the solution separates from the ore and
gathers on the top and in a short period of time is absolutely void of floating slimes
or particles. To make this discovery a practical one, the metallurgist will at once
recognise the necessity of providing means of:
First, removing the solution without disturbing the ore.
Second, ease of applying wash water, and
Third, ease of abstracting the tailings after compression, as they become com-
pacted to such an extent, that they are impenetrable to pick or spade.
To accomplish these ends we have devised the apparatus shewn in the accom-
panying drawings of which:-
Figure 1 is a vertical central section of one construction of apparatus such as
hereinbefore referred to;
Figure 2 is a similar view of the upper part of Figure 1, the plane of section
being at right angles to Figure 1;
to.
Figure 3 is a plan of the cover A³ of the tank and
Figure 4 is a plan of the trolley E, both of which are hereinafter again referred
Like letters indicate like parts throughout the drawings.
A is a cylindrical tank, constructed of rings of plating a¹ a² a³, of diameters
which preferably decrease successively from the top towards the bottom of the
tank. A¹ is a layer of filtering medium, and A3 is a space below it to receive
water and air under pressure as hereinafter described. The lower end of the tank
is carried by a supporting plate B suitably flanged and stiffened which rests
upon bearers C carried by supporting walls D. A³ is a removable top cover for the
tank A, and A' is a removable bottom cover constituting a filter bottom; the top
cover A³ is provided with a circumferential flanged ring A5 adapted to rest upon
a similar ring A6 at the top end of the tank, packing A being interposed between
the meeting faces of the flanged rings A5, A6, to ensure the maintenance of a fluid-
tight joint between them, when they are forced together. Bolts A7 cottared so
as to be readily removable are employed to bolt the two flanges A5, A6 when the
cover A³ is in place on the tank. The filter bottom or cover A is flanged as at A³
and similarly engaged by cottared bolts A', with the supporting plate B; it has a
cylindrical flange A extended downward from it at the centre to protect the cock A
and to rest upon a portion of the trolley E hereinafter referred to.
An important feature of this apparatus is the provision of means by which the
top and bottom covers A³ A* can be removed and replaced with facility without
necessitating the employment of more than one attendant and without the risk
which would be incurred by the use of cranes or similar apparatus. The supporting
walls D are sufficiently widely spaced to enable a trolley E to run between them on
rails F, this trolley is employed for enabling the bottom cover A' to be removed
in the manner hereinafter to be described; the rails F upon which the trolley
travels are available also for bringing into position another trolley into which,
when the bottom cover has been removed the compacted mass of slime is ejected
from the tank.
The top end of the tank is situated between the two parallel rails G, suitably
supported, there being preferably a third and similar rail G between the other two,
parallel with them, and in line with the walls of the tank A, on which three rails
the top cover A³ travels in its removal from the tank and its replacement.
The means by which the bottom cover A is operated will first be described. The
trolley E supports a rising and falling holder E¹ flanged as at E to receive
the flanged portion A° of the bottom of the cover A'; the lower portion E3 of the
holder E¹ extends downward into a vertical guide E* fixed to the trolley enclosing

page_text: a central screw E engaging with a correspondingly screw threaded portion of
the interior of the lower part E³ of the holder. By rotating the screw E³ the
holder E can be raised and lowered vertically, suitable means, such as a feather
in the part E3 entering the groove in the part E, being provided to prevent the
holder E¹ from rotating while it is being raised or lowered. E6 are collars on the
body of the screw E5 which bear against opposite ends of the bearing block E
and prevent the screw from being moved endwise and E8 is a worm wheel fixed to
the lower end of the screw so that by means of a worm E' it can be operated manually
with ease.
The trolley is provided with wheels E which run upon rails F.
To remove the bottom cover A' the trolley E is run underneath it and the
holder E¹ is raised so that its flanged portion E2 engages and supports in the manner
indicated on Figures 1 and 2, the cover A by the flange A2; the bolts A7 are then
withdrawn from the flange A8 and the bottom of the cover; and the screw E³ is
rotated to lower the holder E¹ and cover A' resting upon it through a short distance
so that it may clear the bottom of the tank. Next the trolley with its load of
bottom cover is run out from under the tank and replaced by the other trolley into
which the tank contents are to be discharged. The reversal of these operations
enables the bottom cover A to be readily replaced, when the cottared bolts are put
into position and tightened up, a tight joint with the aid of packing being thus
obtained between the flange and the cover of the supporting plate B.
To enable the top cover A³ to be put on and off it is provided with three lugs A13
each of which retains a screw-threaded rod H as shown; it is to be understood that
in this construction the screw-threaded portion of each rod does not engage with
the lug through which it passes, but serves to engage a nut J situated on the rod
below the lug. The lower part H¹ of the rod H is formed as a fork with two tails
which retains a wheel K flanged to engage with and run upon the rails G. By
operating the nuts J the lugs A13 and with them the cover A3 can be forced upwards
and lowered down; when the cover is thus slightly lifted up from the top end of
the tank A it can readily be carried away laterally upon the wheels K running on
the rails G, or run back again and lowered once more into place with equal facility.
By constructing the apparatus so that the removal of the covers A3 A4 is effected,
mainly by movement in a horizontal direction, the risks attendant upon hoisting
machinery are avoided, and economy of space and convenience of operation are
attained.
M is a pipe through which air and water are delivered into the bottom cover A*,
the air supply passing into the pine M by way of the branch N and valve N¹, and
the water supply passing by way of the pipe O and valve 01. P is a float which
conveniently may be annular and made of cane or bass wood; it floats upon the
top of the contents of the tank and is provided with a flexible tube Q one end of
which is open, and extends down through the float so as to dip into the liquid
upper portion of the contents, the other end being connected to a draw-off pipe R
leading to the precipitation boxes having a valve R¹ and also a test cock R². S is
a pressure-gauge fitted to the top cover to indicate the pressure within the tank.
T (Figure 1) is an escape valve through which the pressure may be relieved before
the top cover is removed. The cock A10 is for the purpose of drawing off the water
in the lower part of the tank whenever required.
The operation of the apparatus described is preferably as follows:-The ore
which has been previously mixed with a suitable solvent solution, which in the
case of gold, and as an example may be a cyanide of potassium solution, has been
preferably allowed to macerate for a suitable period of time say, in ordinary cases
thirty hours, and after such maceration is agitated for a period of time varying
from one to three hours, and is then conveyed to our tank, which may be made of
any suitable size, though preferably of not less than five, nor more than forty, tons
capacity. The tank should first be put in proper working condition by securing
the bottom A firmly, and filling it up to the filtering layer A¹ either with water
or weak solution; this is done merely for the purpose of preventing any portion of
slimy matter or solution from the ore percolating through the bottom, the object

page_text: on
the bottom
are
of this filter being principally to employ the wash water solution thoroughly to all
portions of the bottom ore section. The apparatus may be filled to a point close
up to, but somewhat below the solution draw-off pipe R, and when filled the float I'
is placed on top and the flexible tube Q is connected to the said solution draw-off
pipe. The cover A³ is then pushed over, the packing of same is carefully examined
and the cottared bolts A are tightened. All valves on top except the air inlet S¹
are closed, all valves
closed and air is then
pumped into the top section until a density and pressure have been
obtained which is in accordance with the requirements, and may be as
low as 5 lbs and as high as 100 lbs. per square inch. Properly speaking the
greater the porosity of the charge the less the pressure required, and the greater
the slimy condition of the charge the greater the pressure required. But under
ordinary circumstances and with material of ordinary compactability an average
pressure of 50 lbs. per square inch is very suitable. When the pressure gauge
indicates the desired pressure, matters are allowed to remain in a quiescent state
and from time to time small samples of solution are drawn off by opening the test
cock R2 attached to the solution draw-off pipe R, and when the sample so abstracted
shows absolute clearness, the valve R¹ of the draw-off pipe is opened to such an
extent as to cause the delivery of the solution (caused by the pressure within the
tank forcing the solution through the flexible hose attached to the float) with a
velocity and in such volume as is desired, and as may be required by the subsequent
precipitating capacity, and is continued, until the solution is all abstracted or until
it ceases to flow with absolute clearness, which does not take place until the flexible
hose reaches within a very slight distance of the top layer of slime. To reach this
stage of the operation usually requires one and a half hours, and as soon as the
abstraction of the solution has taken place, the escape valve T on top of the cover
is opened and the pressure is let off, but all other valves on top are closed. Water
is now pumped into the bottom through the pipe M under a pressure sufficient to
either enter through the entire cross section of the charge or to cause it to raise
the charge until it passes one of the lapped sections or plating rings a³ which
immediately of course offers a line of lesser resistance to the water and the water
causes the edge of the ore to break sufficiently to allow the subsequent passage of
air under pressure which is admitted as soon as the quantity of wash water is
sufficient, and the mass is then maintained under agitation until the compacted ore
mass is in a sludgy condition, which is accomplished in a very few minutes, and
as soon as it is accomplished the bottom valves are closed, the escape valve on top
and all other valves except the air pressure valve, are closed, air is again admitted
on top, the mass is again compacted and the wash water which now contains
practically all of the gold solution which was left behind in the first operation in
the way of moisture is abstracted and the gold therefrom recovered by the usual
means. The wash water may also be applied on top of the charge and the ore may
be re-mixed with it by means of mechanical or air pressure agitation.
The water seal may then be withdrawn from the bottom of the tank, and the
cover A removed as hereinbefore explained by a trolley. The air pressure is then
admitted on top and the compacted mass of slime or ore is ejected through the open
bottom into the trolley and carried away.
In case the charge when ready for ejection is so permeable to air as to prevent
its expulsion on account of the air percolating into the charge instead of pressing
against it, a rubber sheet or light top cover is laid directly on the surface
of the charge to stop air-percolation and give the air pressure an impermeable
surface to act on.
:
We have described the method in accordance with the usual routine of practice-
viz. that amalgamation precedes cyanidation; in many instances however, it will
be found that a large percentage of coarse gold escapes amalgamation on account
of the foul condition of such gold and when this coarse gold reaches the cyanide
stage of treatment only a small percentage of it is recovered owing to the long
period of time required for weak solutions to dissolve coarse gold particles. On the

page_text: other hand this coarse, foul, or rusty gold is put in the best possible condition for
amalgamation during its contact with cyanide solution for such period of time as
is usually given to ordinary treatment, say thirty hours, so that it may be advisable,
and of great benefit in such instances to let amalgamation follow cyanidation in
which case the ore after the extraction of the wash water is again agitated in the
extraction tank either by mechanical stirrers or compressed air, and the contents
are then discharged through a pipe just above the filter bottom on to suitable amal-
gamating plates or other appliances.
Although we have described the operation of this invention in connection with
that class of ores generally termed slimes we wish it to be understood that the
process is equally applicable to the treatment of precious metal-bearing ores in a
granular condition, because it will be found that the solvent solution mixed with
this class of ore can be more effectively separated leaving a lesser quantity of residual
solution in the ore in the shape of moisture, hence a greater extraction of the
precious metals.
Our process is also applicable to the washing of ores for the purpose of removing
soluble salts therefrom.
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. In the treatment of ore in a granular or pulpy condition subjecting a mixture
of ore and liquid in a receptacle to air pressure whereby the ore is compacted
into a solid mass at the bottom and the liquid separated out at the top.
2. In the treatment of ore in a granular or pulpy condition for the extraction
of the precious metals contained therein subjecting a mixture of such ore and a
solvent solution in a receptacle to air pressure whereby the ore is compacted into
a solid mass at the bottom and the solution containing the precious metals is
separated out at the top.
3. Recovering precious metals from ores which are in a granular or pulpy con-
dition consisting in suitably mixing and treating the solvent solution and the ore
subjecting the mixture in a receptacle to a high air pressure whereby the ore is
compacted at the bottom into a dense mass and the clear solution containing the
precious metals separated out at the top and forced out of the receptacle by the
pressure within substantially as described.
4. In the treatment of ore in a granular or pulpy condition which has been
compacted by pressure subjecting the compacted mass of ore to an air and water
pressure from below for the purpose of breaking up the mass substantially as and
for the purpose described.
5. The complete process for the treatment of ores in a granular or pulpy con-
dition consisting in mixing with the ore a suitable solvent solution subjecting
the mass in the receptacle to high air pressure whereby the ore is compacted at the
bottom and the clear solution containing the precious metals separated out at the
top and automatically ejected by the pressure within; breaking up the compacted
mass by air and water pressure from below and repeating the process for the further
recovery of the gold bearing solution the mass being again compacted and then
ejected from the apparatus by pressure from above substantially as described.
6. In apparatus of the kind described the employment of a water bottom with a
filter layer, below which latter water under pressure is admitted to prevent the
passage of ore through the layer.
7. The combination with a receptacle such as A of a float P flexible pipe Q
and draw-off cock, substantially as described.
8. The combination with a tank cover such as A³ of jacks connected therewith
and a track at a lower level than the cover, operating substantially as described.
9. The combination with a removable tank bottom such as A4 of a trolley and a
rising and falling holder substantially as described.

page_text: 10. The combination with a tank of a cover such as A³ and tank bottom such
as A each provided with means for lateral removal substantially as described.
11. The combination with a tank having a movable bottom of a cover removable
laterally, substantially as described.
12. In apparatus of the kind hereinbefore referred to the employment of a sheet
or cover for use in the expulsion of the compacted charge substantially as described.
13. The combination and arrangement of parts constituting the complete
apparatus for the treatment of slimes, substantially as described and illustrated
in the accompanying drawings.