IMPROVEMENTS IN TREATING ORES, MINERALS, AND OTHER BODIES CONTAINING METALS TO OBTAIN GOLD, SILVER, AND OTHER PRODUCTS THEREFROM, AND IN THE APPARATUS EMPLOYED THEREIN.
Year: 1874

page_text: LETTERS PATENT to Thomas Clarke, of Wilmslow, in the County of
Chester, M.D., and Edward Smith, of Torquay, in the County of
Devon, F.C.S., for the Invention of "IMPROVEMENTS IN TREATING ORES,
MINERALS, AND OTHER BODIES CONTAINING METALS TO OBTAIN GOLD, SILVER,
AND OTHER PRODUCTS THEREFROM, AND IN THE APPARATUS EMPLOYED
THEREIN.
"
Sealed the 19th February 1875, and dated the 26th December 1874.
PROVISIONAL SPECIFICATION left by the said Thomas Clarke and
Edward Smith at the Office of the Commissioners of Patents, with
their Petition, on the 26th December 1874.
We, THOMAS CLARKE, of Wilmslow, in the County of Chester, M.D.,
and EDWARD SMITH, of Torquay, in the County of Devon, F.C.S., do
IMPROVEMENTS IN
hereby declare the nature of the said Invention for
TREATING ORES, MINERALS, AND OTHER BODIES CONTAINING METALS TO OBTAIN
GOLD, SILVER, AND OTHER PRODUCTS THEREPROM, AND IN THE APPARATUS EM-
PLOYED THEREIN," to be as follows:-
The ores or minerals to be operated upon are first pulverized or ground,
and if necessary roasted to expel volatile substances, such as arsenic
Di 977

page_text: and sulphur, and which may be collected and purified in any ordinary
manner. The ground or ground and roasted material is then mixed with
an alkaline chloride, such as common salt, in the proportion suitable to
cach class of ore, and chloridised in any ordinary manner. If now the
chloridised material is lixiviated with water the salts of gold, copper,
iron, &c., are dissolved, whilst only a portion of the chloride of silver is
dissolved, the amount so dissolved depending on the temperature of the
water used for lixiviation. If cold water is employed the chloride of
silver is nearly insoluble, whilst the mictallic salts above referred to are
readily soluble. The solution thus obtained, which contains also all the
free acid, being duly heated by steam jets or superheated steam or
otherwise, is deprived of its copper by being digested into scrap or
other form of iron in a suitable tank in the usual way. The deposit of
copper thus obtained may contain also any small portion of gold or silver
that may have been dissolved by the cold water. The residue left after
lixiviation, and containing the chloride of silver (and if the one has
been imperfectly or improperly chloridised it may also contain certain
compounds of copper), is now treated with a solution of an alkaline
hyposulphite, preferably with hyposulphite of soda, or with a solution
of ammoniacal gas in water commonly called caustic or liquor ammonia,
or of a salt containing free ammonia, or with a mixture of any alkaline
hyposulphite with any of these ammoni al compounds, in which the
chloride of silver as well as the residuary copper compounds are readily
soluble. The clear solution of silver thus obtained either by hypo-
sulphite of soda alone or with ammonia alone, or both combined, is next
run into a tank, in which are placed sheets of copper in contact with
platinum or other metals carefully arranged to induce galvanic action.
In fact the object is to turn the whole tank into a galvanic battery.
It is not necessary to use the platinum in any weighty form, for it
will be sufficient to use it as shects, foil, or strips, or even as any
platinised solid, so that the due connection between the two metals be
kept up. This connection causes a very rapid deposition of the silver,
and the action is increased by the further addition of ammonia.
If hyposulphite of soda alone is used the action may be aided by
superheated steam by passing galvanic currents in connection with the
platinum and copper to increase the action going on within the tank,
and if necessary by also adding a suitable quantity of ground copper
precipitate, derived from previous operations, to the solution. The silver

page_text: thus obtained may be contaminated with certain compounds of silver or
copper, which may be readily removed by washing with ammoniacal
liquor or solution or hydrosulphite of soda, or both together, such
washings to be put back into the silver precipitating tank. The solution
after being thus deprived of its silver is drawn off (and if ammonia has
been used it may be expelled by the steam jet) and passed into the
ordinary copper precipitating tank.
In the case of ores containing silver, but without any or only with
small quantities of other metals, the chloridised ores may be at once
treated with a solution of the hyposulphite or with ammonia, or with
both combined, without any previous lixiviation, and the silver solution
so obtained be passed into the silver precipitating tank in the manner
herein-before described.
The
It is to be remarked that although by our improved process we employ
agents a little more expensive than those hitherto in use, yet the more
perfect exhaustion of the materials used and the rapid and independent
form of working repays many times over the small extra cost.
platinum, for instance, never requires to be replaced, as it is absolutely
unacted upon by the treatment, and always retains its full market value.
Should tin however be present in any of the ores thus treated it is
unaffected by any of the foregoing operations, and may be consequently
dealt with in the mechanical manner to be now described.
It is a well known fact that by the present method of dressing tin
ores considerable difficulty is experienced in separating certain metallic
and other compounds associated with the tin ore, and having very
nearly the same specific gravity, and which compounds must of necessity
be removed. Now we find that by chloridising the ground tin ore in a
dry state, and independently of any lixiviations or treatment for other
metals, these compounds are decomposed and rendered partly soluble,
and so altered in their specific gravity as to be readily separated from
the tin particle. In case therefore of not wishing to put the tin ore
through any of the processes herein named for the recovery of other
metals it may be at once ground to the requisite fineness in a dry state
by rolling or other mills, mixed with the requisite proportion of salt
and roasted until all the other metals are chloridized. And it is to be
observed that as tin ores have to be roasted in any case, the addition of

page_text: but that they may be stored up in suitable buildings for any length of
time, thus making the two operations of chloridising and of lixiviating,
completely independent of each other.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Clarke and Edward Smith in the Great
Seal Patent Office on the 4th March 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, THOMAS
CLARKE, of Wilmslow, in the County of Chester, M.D., and EDWARD
SMITH, of Torquay, in the County of Devon, F.C.S., send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-sixth day of December, in the year of
our Lord One thousand eight hundred and seventy-four, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said Thomas Clarke and Edward Smith, Her
special license that we, the said Thomas Clarke and Edward Smith, our
executors, administrators, and assigns, or such others as we, the said
Thomas Clarke and Edward Smith, our executors, administrators, and
assigns, should at any time agree with and no others, from time to time
and at all times thercafter during the term therein expressed, should
and lawfully might make, use, excrcise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle
IN TREATING ORES, MINERALS.
of Man, an Invention for "IMPROVEMENTS
OTHER
AND OTHER BODIES CONTAINING METALS TO OBTAIN GOLD, SILVER, AND
PRODUCTS THEREFROM, AND IN THE APPARATUS EMPLOYED THEREIN," upon the
condition (amongst others) that we, the said Thomas Clarke and
Edward Smith, our executors or administrators, by an instrument in
writing under our or their hands and seals, or under the hand and seal
of one of us or them, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that we, the said Thomas Clarke and Edward Smith,
do hereby declare the nature of the said Invention, and in what manner

page_text: the same is to be performed, to be particularly described and ascertained
in and by the following statement thereof, that is to say-
This Invention has for its object improvements in treating ores,
minerals, and other bodies containing metals to obtain gold, silver, and
other products therefrom, and in the apparatus employed therein. For
this purpose the ores or minorals to be operated upon, having been first
sorted if necessary, are pulverised or ground and sifted to the requisite
degree of fineness and uniformity of size and then thoroughly washed
and clutriated, so as to separate all the light, sparry, silicious, and
carthy substances from the heavier mineralised matter, and concentrate
the really valuable portion to the utmost possible extent. The specific
gravity of the gangue or non-mineralised part never averages above
29 and if not removed clogs and harasses all the succeeding operations.
This removal is best effected by our improved buddle or apparatus
herein-after described. The heavier and concentrated material thus
obtained is then to be roasted if necessary to expel volatile substances,
such as arsenic and sulphur, and which may be collected and purified in
any ordinary manner. It is then mixed with an alkaline chloride, such
as common salt, in the proportion suitable to cach class of ore, say in
the ratio of ten per cent. and chlorodised in any ordinary furnace.
As the process of roasting and chlorodising as now performed is very
slow and tedious we propose to shorten the operations by passing a cold
or hot blast of air, which can be regulated at will, through one or more
openings in the furnace whenever it may be considered requisite. If
the chlorodised material when cold is lixiviated with water the salts of
gold, copper, iron, &c., are dissolved, whilst tin if present is untouched,
and only a portion of the chloride of silver is dissolved, the amount so
dissolved depending on the temperature of the water used for lixivia-
tion. If cold water is employed the chloride of silver is nearly insoluble,
whilst the metallic salts above referred to are readily soluble. The
solution thus obtained, which contains also all the free acid (and which
it is essential should be removed) being duly heated by steam jets or
superheated steam or otherwise, is deprived of its copper by being
digested with scrap or other form of iron in a suitable tank in the usual
way. The deposit of copper thus obtained may also contain a small
portion of gold or silver which may have been dissolved by the cold
The residue left after lixiviation and containing the chloride of
silver (and if the ore lias been imperfectly or improperly chlorodised it
water.

page_text: may also contain compounds of copper) is now treated with a solution
of an alkaline hyposulphite, preferably with hyposulphite of soda, or
with a solution of ammoniacal gas in water, commonly called caustic
or liquor ammonia, (purified coal gas liquor will do); or of a salt contain-
ing ammonia, or with a mixture of any alkaline hyposulphite with any of
these ammoniacal compounds in which the chloride of silver as well as
the residuary copper compounds are readily soluble; because we have
found by careful observation and research that silver is far more quickly
and certainly precipitated from alkaline than from acid solutions. The
clear solution of silver thus obtained either by the hyposulphite of soda
or with ammonia, separately or both combined, is next run into a tank,
in which are placed sheets of copper alone or sheets of copper in contact
with platinum or other suitable metal carefully arranged. To induce
galvanic or voltaic action zinc may also be used instead of copper, but
in this case if the silver solution should contain any copper it will be
precipitated with the silver, and so be intermixed with it. Our object
when two metals are used is to turn the whole tank into a galvanic or
voltaic battery.
It is not necessary to use platinum in a solid form, as it will be found
sufficient to use it as sheets, foil, or strips, or even as any platinised
solid, so that the duc connection between the metals be kept up. This
connection causes a very rapid deposition of the silver, and the action is
increased by the further addition of ammonia either to the lixiviating
or silver precipitating tank, or both; indeed, so exhaustive is the solvent
power of ammonia that it will not only, either alone or in combination
with the hyposulphite, dissolve any silver remaining, whether as chloride
or oxide, but it will also dissolve any cupreous chloride resulting from
defective chlorodisation, and even minute particles of metallic copper.
If hyposulphite of soda alone is used the action may be aided by
superheated steam, by passing galvanic currents in connection with the
platinum and copper to increase the action going on within the tank,
and if necessary by also adding a suitable quantity of ground: copper
precipitate derived from previous operations to the solution. The silver
thus obtained may be contaminated with certain compounds of silver or
copper, which may be readily removed by washing with ammoniacal
liquor or solution of hyposulphite of soda, or both together, such
washings to be put back into the silver precipitating tank. The solution
after being thus deprived of its silver is drawn off (and if ammonia has
been used it may be expelled by the steam jet) and passed into the

page_text: CHIC
ordmary copper-precipitating tank, or
may be passed into a tank and the copper precipitated by zinc or by
zine in contact with platinum or other suitable metals.
In the case of ores containing silver but without any or with only
small quantities of other metals the chlorodised ores may be at once
treated with a solution of the hyposulphite or with ammonia, or with
both combined, without any previous lixiviation (except it may be to
remove any acid or other impurity), and the silver solution so obtained
be passed into the silver precipitating tank in the manner herein-before
described.
It is to be understood that when hyposulphite of soda alone is used
any temperature may be employed during any part of the process, but
when ammonia, cither alone or in conjunction with hyposulphite, is used
the process is more economically conducted at ordinary temperatures on
account of the volatile nature of the ammonia.
It is to be remarked that although by our improved process we
employ agents a little more expensive than those hitherto in use, yet the
primary concentration of the mineralised matter, the more perfect
exhaustion of the materials treated, and the rapid and independent form
of working repay many times over any extra cost. The platinum is of
course absolutely unacted on by the treatment, and always retains its
full market value; but it is also to be specially observed that in the case
of ores containing little silver and copper, and where the excess of salt
used in chlorodising may be found to be a suflicient solvent, or where
it is preferred to separate the silver from the copper in smelting rather
than by passing the solution through our silver precipitating tanks (as
we should advise) the concentrated and chlorodised ore may be at once
brought from the furnace, and put into a simpler form of our improved
buddle partially filled with hot water, and there washed or lixiviated
until the silver and copper compounds are dissolved. After allowing a
little time for settling after cach washing the solution may be passed
into the filtering tank, or even at once to the copper precipitating tank,
when according to an old and well known law the copper, silver, and
gold will and indeed must be precipitated together. The precipitate,
when enough has accumulated, may be washed in the buddle until all
soluble salts, silicious matters, and other impurities are removed, and it

page_text: is fitted for the market.
The residue of the ore is of course to be treated
for tin should it be present therein.
So much for ores chlorodised in the usual way, but our ammonia
process is not thus limited, for chlorodisation by salt, and subsequent
precipitation by iron may be rendered altogether unnecessary, because
ammonia with one of its salts added, the chloride of ammonium, forms
one of the most powerful solvents for copper and its compounds known.
To effect this the ore is roasted in a proper furnace until all the sul-
phides are decomposed and rendered amorphous (which the microscope
readily shows), and it is then plunged, hot or cold, into water contain-
ing chloride of calcium or barium, or both, and left for a time to steep.
It is then treated with ammonia, and in the reactions the sulphuric acid
unites with the lime, forming insoluble sulphate of lime, which is
precipitated. One portion of chlorine forms chlorides with the metals,
and the other hydrochloric acid, which when excess of ammonia
is added forms chloride of ammonium, and so by this simple chemical
change the double solvent is obtained. In the case of burnt Spanish
pyrites these facts may be at once demonstrated. The copper and silver
are thus obtained in a clear solution, the iron and all the other impurities
being left behind. The silver may be separated as before, and on the
ammonia being expelled by superheated steam jets in a suitable tank
the oxide of copper is precipitated. The addition of a little fixed alkali
ensures the precipitation of the whole of the copper, dehydrates the
copper oxide, and causes the expulsion of all the ammonia. This
process is not only a very rapid but a very economical one, as (the pro-
cess being a closed one) the ammonia is readily recovered, whilst the
copper and the silver may be smelted on the premises, and obtained in a
state of very great purity.
In the case of argentiferous lead ores it is well known that during the
metallurgic treatment of such ores the silver is ultimately obtained
alloyed with the lead, from which it is very imperfectly separated by
the processes now in use.
It is also well known that if metallic zinc be added to the fused
argentiferous lead the silver separates from the lead, and forms an alloy
with the zinc, the argentiferous zinc so formed rising as a scum to the
surface of the molten metal. We extract the silver from this silver zinc
scum by very carefully chlorodising either with or without the addition

page_text: of sand or other incrt substances, as may be found necessary; then
lixiviating the powdered chlorodised material first with cold water (and
if such solution contains silver it may be passed into the silver precipi-
tating tank), and then lixiviating the residue with a solution of hypo-
sulphite of soda or ammonia, or preferably both combined, and passing
the silver solution thus obtained into the silver precipitating tank, as
previously described. Should tin however be present in any of the ores
thus treated it is unaffected, as previously observed, by any of the fore-
going operations, and may be subsequently dealt with in the chemical
and mechanical manner to be now described.
"
It is a well-known fact that by the present method of dressing ores
containing tin, or as we shall call them tin ores," very considerable
difficulty accompanied with a serious loss of tin is sometimes experienced
in separating certain metallic and other compounds associated with the
tin particle, and having very nearly the same specific gravity, and which
compounds when they occur must of necessity be removed. Now we
find that by chlorodising such tin ores (independently of any lixiviation
or treatment for other metals) these compounds are decomposed and
rendered partly soluble, and so altered in their specific gravity and
otherwise as to be readily separated from the tin particle. In case
therefore of not wishing to put such tin ore through the processes herein
named for the recovery of other metals, it may be at once ground to the
requisite degree of fineness in a dry state by rolling, grinding, or other
mills, sifted and washed in our improved tub or buddle (already
mentioned and to be hereafter described) until all the lighter and
valueless constituents are as far as possible removed. This simple
operation brings the ore into the condition technically termed "whits."
It may now be dried on the roof of the furnace mixed with the requisite
proportion of salt, and with or without the aid of the hot or cold air
blast, roasted until the heavy compounds which interfere with the
dressing of the tin are chlorodised or otherwise changed or decomposed,
so as to be easily removed by washing, and it is to be observed that as
such ores are generally roasted the addition of the salt which effects so
great a change involves little further expense or trouble, and the
chlorodisation can be effected with great facility, because not having to
fear any volatilization or decomposition of silver or copper chloride a
high temperature may be employed; but should there be any volatile
matters in the ore worth collecting, as arsenic or sulphur, these must

page_text: be driven off before chlorodising, and in certain cases, where they are
associated with little silver or copper, even before it is finely powdered
and washed, as the roasting will diminish the bulk, aid the pulverization
and clean the tin. On the other hand, if the different bodies alluded to
are not present in the ore, and it is as not unfrequently essentially a tin
ore, simple grinding and washing. in our buddle, without either roast-
ing or chlorodising, will be sufficient.
In any of these cases then, when the tin ore has been treated as its
variety requires and is ready to be washed, we first place the material
in a suitable receptacle where it can be acted upon by water (or it can
be placed at once in our buddle, if desired), and from which it is washed
by a stream into a circular tub or buddle made in the following
manner: It is in shape somewhat like a brewer's vat, and along the
sides, which may be perpendicular or inclined, are placed pieces of wood
on hinges to act as wings or "bafllers," and to turn each way so as to
break up the whirl of the current, as required. Within the circle of
these wings revolve the spiral blades of a screw fixed in a collar round
a frame, and turning with and by a central shaft. These fans wind (so
to speak) the lighter particles from the surface of the tin upwards and
outwards, and the entire action of the machine is based on the well-
known axiom in tin dressing, that the particles of matter acted upon
should be forced upwards against the downward current. Below these
spiral fans is a double series of lighter fans, which sweep the surface
and tend to distribute the particles of the tin and allow them to settle
equally, while below these are four or more strong horizontal bars of
iron firmly welded into an iron collar, and having metal teeth rivetted
into them to act as rakes, the teeth of one rake intersecting with those
of the others. These rakes not only help to clean the tin of any
impurity, but by their movement and vibration to settle it at the
bottom. As the speed of the shaft and the apparatus attached to the
outer frame thereof can be diminished or increased by a strap running
over opposite cones of pulleys as each series of fans can be altered in its
position on the shaft, as the whole of the fans and rakes can be raised
or lowered together by means of a lever or a weight running over a
pulley, as the angle of the spiral blades may be changed at will, and
as the angle of the side wings can be also increased or diminished, by
all these combined operations any variety of movement may be obtained,
from the most violent to the most. gentle, until the exact degree of

page_text: motion is found which suits the casc.
This variety of motion and the
washing of the ores are still further aided by upward, and if need, be
downward, currents of water from pipes passing into the buddle both
from the sides and the top. One or more doors are inserted at the side
of the buddle near the bottom to remove the washed ore, and a series
of openings is made, say, about six inches apart, having projecting
mouths capable of being opened or shut at will to allow the washings
to escape at different heights; or the water may be made to escape even
inch by inch by tin spouts made to fit such projecting mouths, and having
different degrees of elevation.
When the fans are made to revolve fast or slow, as may be necessary,
the heavier particles of tin or other metal fall to the bottom, and the
lighter and less valuable matter escapes through any one of the openings
at the side as determined on, the movements of the fans being so
regulated as to prevent the tin or other valuable matter, while being
washed, rising high enough to escape. To avoid any risk however from
carelessness, the liquid from the buddle may run over a launder having
stops, and then if need be over automatic tables, so that nothing
worth saving need be lost. Even percussion hammers may be attached
to the sides of the buddle, if desired.
If stamps are in use the machine will wash the crushed orc and
slimes just the same, care being taken that a sufficiency of water is
employed, but if stamps alone are used it is better to crush the orc very
coarsely (say through half-inch grids). and to finish by passing it
through a suitable grinding mill, whereby all the particles are made as
uniform as possible.
Microscopical examinations of ores crushed and ground by certain
new machines have shown us that this important object can be now
attained, and' it cannot be too emphatically stated that the more nearly
this uniformity approaches to the size of the tin molecule, which may
be taken generally as passing through a sixty or seventy hole sieve, the
more decidedly will gravitation operate, and the action of our improved
buddle, as a separating agent, be more efficient. Indeed the great
objection to stamps is, that acting unequally and crushing the tin
molecule unnecessarily, too large a quantity of "fine" tin is produced,
and we should advise their disuse altogether. It may then be chlorodised
and rewashed, so that any particles adhering to the tin grains are more

page_text: thoroughly separated, and the per-centage of tin increased in the dressed
ore sent to market.
Any number and size of buddles may be employed, and they are
equally well adapted for washing manganese, ores, and other substances.
Their height may be also increased or diminished according to the
delicacy and minuteness of separation required.
Should the cffluent water from these circular tubs or buddles be
found to contain silver, or any other valuable material, we treat it in
the manner already herein-before described. In this way the trouble-
some process of stamping and the tedious, elaborate, and wasteful
apparatus now used for tin dressing are avoided. Even should the tin
ore therefore be treated for other metals the advantage of our improved
method of obtaining tin is very great.
Our improvements are also applicable to the extraction of any of the
metals before specified when in a state of solution, as, for instance, in
the case of mine waters holding such metals in solution.
Another great advantage of our improved process is that we are not
compelled to treat the chlorodised ores in a hot state, as is now the
case, but that they may be stored up in suitable buildings or sheds for
any length of time, thus making the two operations of chlorodising
and lixiviating completely independent of each other, so that if one
part of the process is interrupted the working of the other is not
impeded.
The form and disposition of the tanks are matters of detail to be
determined upon according to the peculiarities of each individual case.
The tanks however we propose to adopt are as follows :—
"
1st. The lixiviating or washing tank. This is merely a modifi-
cation of our buddle with such a combination of metals instead of iron.
as we know will be unaffected by the solution.
2nd. The filtering" tank. This may be made of wood about 5 feet
high, and divided into three compartments. (1.) the upper part, say,
two or three feet deep (as it is used either to filter or lixiviate on the
ordinary plan, for it will do both), is to be filled with the solutions of
the metals from the lixiviating buddles. (2.) The middle one, say

page_text: nine inches deep, is to act as the filter; it has a floor and lid of wood
perforated to allow the liquid to drain through, and is covered at the
bottom with clinkers gradually diminishing in size, and at the top a
layer of straw or ling with or without a slip of canvas tacked on by tin
nails on the under surface of the lid over the perforations. Both floor
and lid may be loose, and rest on supports from the sides, so that they
may be raised at will, and the materials acting as the filter removed,
washed, and replaced or renewed. (3.) The lowest compartment, say
one or two feet deep, is that into which the solution drains, and may be
lined with tiles, patent tinned lead carefully soldered, or, what is better,
with the metallic combination above referred to. One or more glass
tubes may be connected with the inside of this compartment, so that the
height and quality of the liquid may be observed. The liquid may be
drawn off by a suitable tap about two or three inches from the bottom,
allowing any sediment to settle, and ensuring the liquid coming out
perfectly clear. A door may be provided for the lowest compartment
to remove any deposit, which may be rewashed. These doors may be
casily made secure by having bevilled edges packed with strips of
vulcanised india-rubber, and firmly pressed in by any suitable apparatus.
This tank may be also used for lixiviation by having slides on the under
side of the filter to close or open the perforations, allowing the liquor to
drain from or soak into the ore, and having a door at the side of the
upper compartment to remove the washed matter.
3rd. The copper precipitating tank is lined in the same way, but
with a protective lining of wood, and is of any convenient size, but
having about 12 or 18 inches from the bottom a rack of wooden bars
half an inch to an inch apart on which scrap or other iron rests, and
from which, when shaken, the precipitate falls to the bottom between
the bars; when a sufficient quantity has accumulated it may be removed
and washed. A door is provided for removing the precipitate similar
to that in the preceding tank.
4th. The silver precipitating tank may be lined as before, or with
white glazed tiles. It may be about 3 feet deep and three fect wide,
having sheets of copper, say six inches apart. passing from the top and
bottom alternately so as to present an extensive surface to the liquid.
If two metals are used on each copper plate are fastened bars of wood
covered with platinum foil. A more electro-positive metal, such as

page_text: zinc may take the place of copper in this tank if preferred, or the
positions of the copper and platinum may be reversed. The solution
enters at one end of the tank and passes over the surface of the metals,
(the flow washing the silver off as it is deposited) until it passes out at
the other end into the copper precipitating tank. As each compartment
is separate small doors are provided to extract the silver deposited in
each (the liquid being emptied by a syphon or a tap); but the tank may
be fitted with a cover and locked, and not necessarily interfered with for
days unless the sheets of copper require to be replaced or the silver
removed. If the silver is not all extracted the tank must be prolonged
(or even two or three tanks may be placed side by side) and the rapidity
of the inflow diminished. All the copper dissolved is reprecipitated in
the next tank and so saved. As a matter of convenience this tank may
run on wheels or be placed in a separate building.
Figure 1 is a sectional view of our improved buddle; 1 is the shaft
of the water wheel or other motive power, but the machine may be
worked equally well from below; 2, 2, are the opposite cones of the
pullies which are employed to allow of the speed of the machine being
varied; 3, 3, 3, are supports for a triple set of shafts; 4 is an endless
band running over the cones 2, 2; 5 is a central shaft which serves to
turn the fans and rakes (marked 11, 12, 13, 14). Any number of such
fans and rakes may receive motion from this shaft; 6 is a lever to raise
or lower the framework which is arranged to slide up and down the
central shaft 5, and to which the fans and rakes 11, 12, 13 and 14 are
fixed in their movable iron collars so as to allow of their respective
heights being varied. A pulley and weight arrangement may however
be employed in lieu of such lever if preferred; 7 is the framework
sliding up and down the central shaft 5 on which the fans and rakes
11, 12, 13, and 14 are fixed by any suitable means, and which is moved
as may be required by the lever 6; 8 is a spout which serves to convey
the material to be washed to the buddle; 9 is a pipe which conveys
water to the top of the buddle in order to dilute and wash the ore. This

page_text: of the liquid acting therefore as side wings. If necessary air may be
forced into these pipes in order to render the water inore buoyant.
Figure 4 shows a sectional view of the filtering or lixiviating tank;
1 is an upper compartment in which the solution containing the metals
is placed; 2 is a door formed therein for the purpose of removing the orc
if the tank is used for lixiviation; 3 is the filter; 4 is a lower compart-
ment into which the filtered solution drains through perforations; 5 is
the handle of a slide which serves to open or close such perforations;
6 is a tap for removing the filtered liquor after it has settled; 7 is a
glass tube which communicates with the interior of the lower compart-
ment 4, and which is provided for the purpose of shewing the height
and quality of the liquid contained in such compartment; 8 is a small
door through which any deposit or refuse may be washed out when
necessary.
Figure 5 is a sectional view of the silver (galvanic) precipitating tank,
in which 1 is an inlet tap, and 2 an outlet tap; 3, 3, 3, 3, indicate
partitions of wood which divide the interior of the tank into separate
chambers; 4 and 4" are alternate sheets of zinc or copper from top and
bottom, and fixed into wooden grooves attached to the sides of the tank;
5 are bars of wood covered with platinum foil and compressed by means
of a wooden screw 6 against the surface of copper or zinc; 7 are arrows
indicating the course of the currents.
Figure 6 is a plan view of No. 5. 1 indicates a sheet of zinc or
copper from the top; 2 indicates a sheet of zinc or copper from the
bottom; 3 indicates the slips or bars of wood covered with platinum foil
as previously described; 4 indicate grooves at the side of the tank into
which the sheets of zinc or copper are fixed.
Having now described the nature of our said improvements and the
manner of carrying the same into effect, we would have it understood
that what we desire to claim is.-
1st. The concentration of the mineralised matter in the ores by
washing away the valueless portions, substantially in the manner and for
the purposes herein-before set forth and described.
And The employment of a hot or cold air blast in roasting or
2nd. The employment of a hot or cold air blast in roasting
or

page_text: chlorodising, substantially in the manner and for the purposes herein-
before set forth and described.
3rd. The employment of alkaline hyposulphites (preferably the hypo-
sulphite of soda), and of ammonia either separately or together for the
solution of the metals specified, substantially in the manner herein-before
set forth and described.
4th. The obtaining of the silver separate from other metals, sub-
stantially in the manner and for the purposes herein-before set forth
and described.
5th. The addition of ammonia either to the lixiviating or to the silver
precipitating tank, or both, substantially as and for the purposes herein-
before set forth and described.
6th. The use of superheated steam if hyposulphites alone are used,
and the passing of galvanic currents derived from any suitable source to
aid the galvanic or voltaic action, and the mixing with the solution any
requisite quantity of powdered copper precipitate, substantially in the
manner and for the purposes herein-before set forth and described.
7th. The precipitation and deposition of silver and copper from
alkaline and ammoniacal solutions, substantially in the manner and for
the purposes herein-before set forth and described.
8th. The rapid lixiviation and solution of the substances in our
improved buddle after chlorodisation, substantially in the manner and
for the purposes herein-before set forth and described.
9th. The process of desilvering lead by chlorodisation of the zinc scum
and subsequent solution and precipitation of the silver, substantially in
the manner and for the purposes herein-before set forth and described.
10th. The constructing the lixiviating filtering copper precipitating
and silver precipitating tanks for obtaining copper and silver, sub-
stantially in the manner set forth and described.
Lastly. The chlorodisation of certain tin ores whereby the matters
interfering with the separation of the tin oxide are either changed,
decomposed, or chlorodised, and also the construction and use of the
apparatus whereby the operation of tin dressing especially is very

page_text: materially shortened and improved, and the cost of production greatly
diminished, substantially in the manner herein-before set forth and
described.
In witness whereof, we, the said Thomas Clarke and Edward Smith,
have hereunto set our hands and seals, this Fifteenth day of
February, in the year of our Lord One thousand eight hundred
and seventy-five.
THOMAS CLARKE (L.S.)
EDWARD SMITH (L.S.)