of and Apparatus for Treating and Desulphurizing Ores.
Year: 1895

page_text: Date of Application, 22nd Jan., 1895
Complete Specification Left, 5th Mar., 1895-Accepted, 11th May, 1895
PROVISIONAL SPECIFICATION.
Process of and Apparatus for Treating and Desulphurizing Ores.
I, JAMES YATE JOHNSON, of 47 Lincoln's Inn Fields, in the County of London,
Gentleman, do hereby declare the nature of this invention (which has been
communicated to me from abroad by Louis Pelatan, of Paris, France, and Fabrizio
Clerici, of Milan, Italy, Engineers,) to be as follows:-
This invention relates to a certain novel process and apparatus for desulphurizing
and dead-roasting refractory ores and extracting the precious metals from the same.
In the reduction of refractory ores of gold and silver, it has been found
practically impossible by the processes heretofore employed to roast ores containing
more than thirty per cent. of sulphur and desulphurize them in one and the same
furnace to a point where only a trace of sulphur remains. Concentrates or pyrites
roasted in a furnace without fire will contain, when the process has been completed
not less than two per cent. of sulphur which is too large a percentage to permit of
obtaining good results by chlorination. If fire be applied in the furnace in which
said ores have been roasted for the purpose of driving off the two per cent.
of sulphur remaining in the concentrates or pyrites, it is practically impossible to
avoid heating the same so suddenly that they will bake into hard lumps, instead of
burning thereby rendering a perfect oxidation roasting impracticable.
It has been found necessary in chlorination works, in treating concentrates of
pyrites to employ two separate furnaces one for roasting the ore to a point where
not more than about two per cent. of sulphur remains and a second and separate
furnace for driving off this remainder by dead roasting. The increased extent and
cost of the plant due to the necessity of having this additional furnace and the
greater time and labor required in carrying out the process of treatment, is a serious
item in the expense of operating the plant. It is the purpose of this invention to
remove this difficulty, to simplify the construction and reduce the cost of the plant
or reduction works and diminish the expense of recovering the precious metals from
their refractory ores.
It is the purpose of this invention to this end to provide a novel method or process
of roasting refractory ores of the precious metals to the point of practical
desulphurization at one and the same continuous operation.
It is a further purpose to provide a novel form of furnace for practising the said
method or process; and, finally, this invention also aims at the provision of an
improved apparatus whereby the processes of desulphurizing, chlorinating, and
separating or precipitating the precious metals from their chloride solutions, may be
continuously and automatically carried on, with a large resulting guin in economy
of time, labor and expense and an increased yield of the precious metals.
To enable this invention to be fully understood and practised I will proceed to
describe said process and apparatus in detail.
The furnace is constructed of suitable masonry and inclosed at the sides and the
top. The structure contains a chamber which is preferably of greater leugth than
width and from the central part of the top rises a chimney. The bottom of the
chamber consists of a floor arched on its lower face to form the top of a fire chamber
having a suitable grate and adapted to the consumption of either coal or wood. The
floor terminates, at one end at a little distance from the end wall of the furnace
thereby forming an opening which overhangs an outlet chute for a purpose presently
to be explained. The chute is formed by inclining the outer face of the end wall of

page_text: the fire-chamber, the inclined surface being caused to traverse an opening in the end
wall of the furnace structure.
Within the chamber is arranged a series of horizontal soles formed of cast-iron
and separated from each other by substantially equal intervals. These soles extend
across the width of the chamber and are supported by rolls which are journaled upon
fixed axes in recesses in the side walls of the furnace. The length of the soles is
somewhat in excess of the length of the chamber and their ends lie in or should the
soles be moved horizontally on their rolls are adapted to pass into openings in the
end walls of the structure. The soles are moved in the manner referred to by means
of chains secured to their ends and passing through openings in the walls the
arrangement being such that the alternate soles shall move in the same direction.
For example if the upper sole is drawn towards the left hand the sole next
beneath it will be drawn toward the right; the third towards the left and so on.
As they emerge from the end walls of the structure they pass between parallel
extension walls on which are mounted supplemental supporting rolls. The chains
are operated by independent drums or any other suitable device.
Immediately above each sole is arranged a series of hanging rakes, each rake
consisting substantially of a plate of refractory material supported upon a horizontal
axis arranged transversely to the sole and at such a distance above it that the lower
edge of the rake just clears the surface. All the rakes in each series are connected
together by a rod or other suitable connection attached at one end to a bar which
passes through an opening in the end wall of the chamber and is connected to an
arm pivotally mounted in such manner that it can swing, as the sole
is drawn into the chamber, thereby allowing all the rakes to assume an
inclined position so that they can pass over any ore resting on the sole.
On the other hand when the sole is withdrawn from the chamber the rakes
will be held rigidly in vertical position and will sweep the surface of the sole.
The bars and arms are therefore, arranged alternately at opposite ends of the
soles. The lowest series of rakes overhangs the sole resting upon the floor of the
chamber and as this sole is not moved the rakes are themselves made movable by
means of a long rod which passes at each end through an opening large enough to
allow the rakes to pass. Each end of said rod is connected to a chain which is
operated like one of the chains. A slender chain is connected to one end of the rod
over the outlet-chute and to the connection which communicates inclination to said
rakes. By this arrangement the rakes are held in vertical position when moving in
one direction and will sweep the ore resting on the lower sole into the opening by
way of which it will descend to the outlet chute. When moving in the other
direction the rakes are free to swing into an inclined position and pass over
whatever may be lying upon the sole.
By rigidly attaching a rod to the pivotal axis which supports the arm and allowing
the rod to hang down outside the furnace, the rod of the rakes may be drawn to a
limited extent out of the opening causing the rakes to assume an inclined position as
heretofore described.
I have shewn the chamber provided with seven of the soles as this number is
preferable though either more or less may be used. In use, the fourth sole counting
from the top is of such length or is so placed as to extend 'from one end wall of the
chamber to the other. The other soles are so placed as to provide au opening at
alternate points between their ends and said end walls. The products of com-
bustion passing from the fire box through the opening at the end of the lower sole, flow
between the latter and the sole next above, passing between its end and the other end
wall, thence between the second and third soles and around the end of the latter,
into the space between the third and fourth soles. After traversing the space
between the latter, the hot products and gases enter pipes which communicate with
said space through the side walls and thence pass upward and enter the lower part
of the chimney. By this arrangement no fire is allowed to enter the parallel spaces
between the four upper soles. The ore is supplied to the chamber by means of an
automatic feeder mounted on the top of the structure at the end through which the

page_text: upper sole is drawn outward. The feeder consists of a hopper having beneath
its contracted throat an equalizing fan wheel by the rotation of which the pulverized
ore is caused to pass through the inlet opening and enter the chamber in a
substantially uniform stream. The fan wheel is driven at a constant speed by any
suitable means.
The manner of operating the desulphurizing furnace is as follows: The furnace
being suitably charged with ore and the proper degree of heat being established,
the ore lying upon the three lower soles is roasted by the flames in conjunction
with the oxygen of the air which mingles with the products of combustion the
entrance of the air being amply provided for by the aforesaid openings. The ore
lying upon the four upper soles however will be roasted by the heat of its own
combustion the products of combustion being practically excluded from that portion
of the chamber lying above the fourth sole from the bottom. The ore in this
portion of the chamber will be roasted to the point where all its sulphur excepting
one to three per cent. or thereabout, is driven off. When this result is obtained
the ore is transferred from the space above the sole to the soles lying below it.
This is accomplished by drawing the sole which extends from end wall to end wall"
as aforesaid toward say the right hand the sole next beneath it remaining in
position. The rakes being rigidly held in vertical position sweep the ore off the
sole above, as the latter moves outward and spread it with substantial uniformity
on the sole beneath. The latter being, in turn, drawn out toward, the left hand,
spreads the ore it supports in a similar manner upon the sole beneath it, which
being, in its turn, drawn out toward the right hand, deposits the ore on the sole
resting on the floor of the chamber. It is removed from this sole by drawing the
rakes out toward say the right hand, said rakes sweeping the ore off the surface
into the opening through which it passes to the outlet chute.
In operating the furnace as the ore is fed in at the top the mode of procedure is
substantially as follows: The upper sole being drawn out toward say the left
hand the ore is fed in by means of the hopper and fan wheel the upper sole being
meantime, drawn inward by a uniform motion. The ore is thus spread with
approximate uniformity on the surface of said upper sole, the rakes being thrown
into an inclined position, as the sole moves into the chamber as shown in dotted
lines. After remaining a suitable length of time, the, upper sole is drawn out
toward the left, thereby depositing the ore upon the next sole beneath. As the
upper sole returns into the chamber it receives a fresh charge of ore from the
feeder. The second sole being now drawn out toward the right, the ore deposited
on it is spread on the third sole and the second being drawn into its normal
position receives, in due time, a second charge of ore from the upper sole in the
same manner and the third sole from the top receives its charge from the one next
above in a similar way.
It will be noted that, as the ore descends from one sole to
the next below it is subjected to an increased temperature. By the successive
increments of heat to which it is subjected in traversing the upper portion of the
chamber its sulphur is driven off save only from one to three per cent. or there-
about as already stated. Its treatment in passing successively to the fifth sixth
and seventh soles on each of which it is roasted in conjunction with air and fire
eliminates the remaining sulphur, or practically so.
It is evident that the furnace may be filled with ore on the four upper soles,
including the sole extending as aforesaid and those above, before the process of
roasting begins and that the first operation after the roasting has progressed to the
proper point will be to transfer the ore on the extended sole to the sole next below,
then to shift the ore on the three soles next above the extended sole one step
downward, a second charge being then fed to the upper sole. When all the soles
are occupied the ore is simply shifted from the sole on the floor of the chamber to
the outlet chute then from each sole next above to the one below, in succession.
This operation is performed at intervals of from ten to thirty minutes according to
the nature of the ore and the circumstances of each case. A quantity of ore may

page_text: be transferred from the upper to the lower sole in the manner described in a very
short time and a single workman can operate three such furnaces without excessive
effort.
Each furnace is capable of roasting from six to ten tons of ore per day, to
practically complete desulphurization, the daily output varying according to the
nature of the ore.
When
It is preferred to supply the automatic feeder of the furnace with concentrates,
or dry, crushed pyrites, or other ores, by means of a spiral carrier which discharges
directly into the hopper. The roasted ore when discharged by way of the outlet
chute falls by its own gravity into a receiver from which it is taken by spiral
carriers to a plurality of tanks or vats which are duplicates one of another have
filtering layers at bottom, formed of any suitable material, and below said filtering
layers and the perforated false bottoms on which they rest are communicating
chambers which receive the filtered liquid. In a convenient position above the
vats are arranged reservoirs lined with lead or other suitable material, and con-
taining a chlorine solution, containing about one per cent. of free chlorine.
the tanks or vats are filled with roasted ore by the spiral carriers, they are closed
by a cover which is applied with care and the chlorine solution is allowed to run
through the mass of roasted ore. The gold is dissolved thereby, or, to speak more
accurately is transformed into a chloride which is readily soluble in water.
chloride solution is passed through the filtering material into the communicating
chambers from which said solution is conveyed by a pipe to a series of precipitating
vessels in which the precious metal or metals are eliminated. The passage of the
chloride solution through the filtering material may be expedited by means of
atmospheric pressure a pipe being arranged to connect the series of chainbers with
a pump by which the air is withdrawn from said chambers. The normal
atmospheric pressure on the solution in the tanks or vats forces said solution
through the filtering material, and, as the communicating chambers are tightly
closed against all access save through the filtering material the pressure also serves
to drive the filtered solution through the pipe and the series of precipitating
vessels.
This
The precipitating vessels contain chips or particles of aluminium or zinc resting
on perforated diaphragnis near the lower ends of said vessels. The outlet to each
vessel is above the mass of aluminium or zinc particles and they are connected in
series, so to speak, by pipes leading from said outlets to the inlets which are below
the perforated diaphragms. The aforesaid pipe enters the inlet of the first vessel
and a pipe extends from the outlet of the last vessel over a tank which receives the
fluid after it has traversed the vessels.
The gold contained in the chloride of gold solution after passing through the
filter is precipitated by the aluminium part cles or by the zinc and settles thereon
in the form of a fine powder. Being detached by the continuous upward current
the precipitated particles work their way downward by their own gravity and
collect in the lower ends of the vessels.
In some cases it may be necessary to allow the chlorine to act upon the ore for
a longer time than that occupied by the chlorine solution in percolating the mass
of ore in the tanks or vats and for this purpose the connection between the tanks
or vats and the chambers is closed and the chlorine solution is retained in the
tanks as long as may be necessary. This treatment effects a considerable economy
in the consumption of chlorine.
A tank is provided containing a mass of chips, turnings or particles of aluminium
by which any small quantities or traces of gold still remaining in the solution after
coming from the precipitating vessels are collected and saved.
Should the ore contain free gold it may be obtained by allowing the tailings
from the tanks to run upon amalgamated copper plates.
After chlorination, the coarse gold which is not dissolved by the chlorine
solution is so thoroughly cleansed by the action of said solution that it can be

page_text: caught and retained by the copper amalgamated plates upon which the tailings are
discharged as last described.
Dated this 22nd day of January 1895.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.
Appar
Petals and spa Ores.
I, JAMES YATE JOHNSON of 47 Lincoln's Inn Fields. in the County of
London, Gentleman, do hereby declare the nature of this invention (which has
been communicated to me from abroad by Louis Pelatan, of Paris, in the Republic
of France and Fabrizio Clerici, of Milan in the Kingdom of Italy Engineers) and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
C
This invention relates to a certain novel process and apparatus for desulphurizing
and dead roasting refractory ores and extracting the precious metals from the
same..
In the reduction of refractory ores of gold and silver, it has been found
practically impossible, by the processes heretofore employed, to roast ores con-
taining more than thirty per cent. of sulphur and desulphurize them in one and the
same furnace to a point where only a trace of sulphur remains. Concentrates or
pyrites, roasted in a furnace without fire will contain when the process has been
completed not less than two per cent. of sulphur which is too large a percentage to
permit of obtaining good results by chlorination. If fire be applied in the furnace
in which said ores have been roasted for the purpose of driving off the two per cent.
of sulphur remaining in the concentrates or pyrites, it is practically impossible to
avoid heating the same so suddenly that they will bake into hard lumps instead of
burning thereby rendering a perfect oxidation roasting impracticable.
It has been found necessary in chlorination works in treating concentrates of
pyrites to employ two separate furnaces one for roasting the ore to a point
where not more than about two per cent. of sulphur remains and a second and
separate furnace for driving off this remainder by dead roasting. The increased
extent and cost of the plant due to the necessity of having this additional furnace and
the greater time and labour required in carrying out the process of treatment is
a serious item in the expense of operating the plant. It is the purpose of this
invention to remove this difficulty, to simplify the construction and reduce the cost
of the plant or reduction works and diminish the expense of recovering the precious
metals from their refractory ores.
It is the purpose of this invention to this end to provide a novel method or
process of roasting refractory ores of the precious metals to the point of practical
desulphurization at one and the same continuous operation.
It is a further purpose to provide a novel form of furnace for practising the said
method or process; and finally this invention also aims at the provision of an
improved apparatus whereby the processes of desulphurizing chlorinating and
separating or precipitating the precious metals from their chloride solutions may
be continuously and automatically carried on with a large resulting gain in economy
of time labour and expense and an increased yield of the precious metals.
To enable this invention to be fully understood and practiced I will proceed to
describe the said process and apparatus in detail reference being had for this
purpose to the accompanying drawings in which―
Figure 1 is a vertical longitudinal section showing the novel desulphurizing
furnace. Fig. 2 is a transverse section of the same.

page_text: :
Fig. 3 is a sectional elevation showing a complete plant or reduction works for
desulphurizing and dead roasting chlorinating and precipitating the precious metals
from their refractory ores in accordance with this invention. Fig. 4 is a sectional
view of the same the line of section being at right angles with that in Fig. 3.
Fig. 5 is a detail section showing one of the precipitating and collecting
vessels.
The furnace is constructed of suitable masonry and inclosed upon four sides
and the top. The structure contains a chamber 2 which is preferably of greater length
than width and from the central part of the top rises a chimney 3. The bottom of
the chamber 2 consists of a floor 4 arched on its lower face to form the top of a
fire chamber 5 having a suitable grate 6 and adapted to the consumption of either
coal or wood. The floor 4 terminates at one end at a little distance from the end
wall of the furnace thereby forming an opening 7 which overhangs an outlet
chute 8 for a purpose presently to be explained. The chute 8 is formed by
inclining the outer face of the end wall of the fire chamber the inclined
surface being caused to traverse an opening 9 in the end wall of the furnace
structure.
Within the chamber 2 is arranged a series of horizontal soles 10 formed of
cast iron and separated from each other by substantially equal intervals. These
soles extend across the width of the chamber and are supported by rolls 12
which are journalled upon fixed axes 13 in recesses 14 in the side walls of the
furnace. The length of the soles 10 is somewhat in excess of the length of the
chamber 2, and their ends lie in, or, should the soles be moved horizontally on
their rolls 12, are adapted to pass into openings 15 in the end walls of the structure.
The soles are moved in the manner referred to by means of chains 16, secured to
their ends and passing through openings in the walls, the arrangement being
such that the alternate soles shall move in the same direction. For example
if the upper sole 10 is drawn toward the left hand, in Fig. 1, the sole next beneath
it will be drawn toward the right; the third toward the left and so on. As they
emerge from the end walls of the structure they pass between parallel extension
walls 17 on which are mounted supplemental supporting rolls 18.
The chains 16
are operated by independent drums 19 or any other suitable device.
Immediately above each sole is arranged a series of hanging rakes 20 each rake
consisting substantially of a plate of refractory material supported upon a hori-
zontal axis arranged transversely to the sole and at such a distance above it that
the lower edge of the rake just clears the surface. All the rakes in each series
are connected together by a rod or other suitable connection 21 attached at one
end to a bar 22 which passes through an opening 23 in the end wall of the
chamber 2 and is connected to an arm 24 pivotally mounted in such manner that it
can swing as the sole is drawn into the chamber 2 thereby allowing all the rakes 20
to assume an inclined position so that they can pass over any ore resting on the
scle. On the other hand when the sole is withdrawn from the chamber 2 the
rakes will be held rigidly in vertical position and will sweep the surface of the sole.
The bars 22 and armis 24 are therefore arranged alternately at opposite ends of the
soles 10. The lowest series of rakes overhangs the sole resting upon the floor of
the chamber 2 and as this sole is not moved the rakes are themselves made
moveable by means of a long rod 25 which passes at each end through an
opening 26, large enough to allow the rakes to pass. Each end of said rod is
connected to a chain 27 which is operated like one of the chains 16. A slender
chain 28 is connected to one end of the rod over the outlet chute 8 and to the
connection 21 which communicates inclination to said rakes. By this arrangement
the rakes are held in vertical position when moving toward the right, in Fig. 1,
and will sweep the ore resting on the lower sole into the opening 7 by way of
which, it will descend to the outlet chute 8. When moving toward the left hand
the rakes are free to swing into an inclined position and pass over whatever may be
lying upon the sole.
By rigidly attaching a rod 22" to the pivotal axis 24 which supports the arm 24

page_text: and allowing the rod to hang down outside the furnace as seen in dotted lines in
Fig. 1, the rod 21 may be drawn to a limited extent out of the opening 23 causing
the rakes 20 to assume an inclined position as heretofore described.
I have shown the chamber 2 provided with seven of the soles 10 as this number
is preferable though either more or less may be used.. In use the fourth sole
counting from the top is of such length or is so placed as to extend from one end
wall of the chamber to the other as shown in Fig. 1. This sole is distinguished
from the others by the reference numeral 10. The other soles 10 are so placed as
to provide an opening at alternate points between their ends and said end walls.
The products of combustion passing from the fire box through the opening 7, at the
end of the lower sole, flow between the latter and the sole next above, passing
between its end and the other end wall, thence between the second and third soles
and around the end of the latter into the space between the third and fourth soles.
After traversing the space between the latter, the hot products and gases enter
pipes 29 which communicate with said space through the side walls and thence pass
pward and enter the lower part of the chimney 3. By this arrangement no fire is
allowed to enter the parallel spaces between the four upper soles.
The ore is supplied to the chamber by means of an automatic feeder mounted on
the top of the structure 1 at the end through which the upper sole 10 is drawn out-
ward. The feeder consists of a hopper 30 having beneath its contracted throat an
equalizing fan wheel 31 by the rotation of which the pulverized ore is caused to
pass through the inlet opening 32 and enter the chamber 2 in a substantially
uniform stream. The fan wheel 31 is driven at a constant speed by any suitable
means.
The manner of operating the desulphurizing furnace is as follows: The furnace
being suitably charged with ore and the proper degree of heat being established the
ore lying upon the three lower soles 10 is roasted by the flames in conjunction with
the oxygen of the air which mingles with the products of combustion the entrance
of the air being amply provided for by the openings, 7 and 26. The ore lying
upon the four upper soles, however, will be roasted, by the heat of its own
combustion, the products of combustion being practically excluded from that
portion of the chamber lying above the fourth sole from the bottom.
The ore in
this portion of the chamber 2 will be roasted to the point where all its sulphur,
excepting one to three per cent., or thereabout, is driven off. When this result is
obtained the ore is transferred from the space above the sole 10", to the soles lying
below it. This is accomplished by drawing the sole 10 toward the right hand of
Figure 1, the sole 10 next beneath it remaining in the position shown in said figure.
The rakes 20, being rigidly held in vertical position, sweep the ore off the sole 10%
as the latter moves outward and spread it with substantial uniformity on the sole 10
beneath. The latter being, in turn, drawn out. toward the left hand, spreads the
ore it supports in a similar manner upon the sole beneath it, which being, in its
turn, drawn out toward the right hand, deposits the ore on the sole resting on the
floor of the chamber. It is removed from this sole by drawing the rakes out'
toward the right hand of Figure 1, said rakes sweeping the ore off the surface into
the opening 7, through which it passes to the outlet chute 8.
In operating the furnace, as the ore is fed, in at the top, the mode of procedure is
substantially as follows:-The upper sole 10 being drawn out toward say the left hand
of Figure 1, the ore is fed in by means of the hopper 30 and fan-wheel 31, the upper
sole being, meantime, drawn inward by a uniform motion. The ore is thus spread
with approximate uniformity on the surface of said upper sole, the rakes 20, being
thrown into an inclined position, as the sole moves into the chamber, as shown in
dotted lines. After remaining a suitable length of time, the upper sole is drawn.out
toward the left, thereby depositing the ore upon the next sole beneath.
upper sole returns into the chamber, it receives a fresh charge of ore from the
feeder. The second sole being now drawn out toward the right, the ore deposited
on it is spread on the third sole, and the second being drawn into its normal
position, receives, in due time, a second charge of ore from the upper sole in the
As the

page_text: same manner, and the third sole from the top receives its charge from the one next
above in a similar way. It will be noted that, as the ore descends from one sole
to the next below, it is subjected to an increased temperature. By the successive
increments of heat to which it is subjected, in traversing the upper portion of the
chamber 2, its sulphur is driven off, save only from one to three per cent., or there-
about, as already stated. Its treatment in passing successively to the fifth, sixth,
and seventh soles, on each of which it is roasted in conjunction with air and fire,
eliminates the remaining sulphur, or practically so.
It is evident that the furnace may be filled with ore on the four upper soles,
including the sole 10" and those above, before the process of roasting begins, and
that the first operation, after the roasting has progressed to the proper point, will be
to transfer the ore on the sole 10ª to the sole next below, then to shift the ore on the
three soles next above 10" one step downward a second charge being then fed to the
upper sole.
When all the soles are occupied, the ore is simply shifted from the sole
on the floor of the chamber 2 to the outlet chute 8, then from each sole next above
to the one below, in succession. This operation is performed at intervals of from
ten to thirty minutes, according to the nature of the ore and the circumstances of
each case.
A quantity of ore may be transferred from the upper to the lower
sole 10, in the manner described, in a very short time and a single workman can
operate three such furnaces without excessive effort. Each furnace is capable of
roasting from six to ten tons of ore per day, to practically complete desulphuriza-
tion, the daily output varying according to the nature of the ore.
It is preferred to supply the automatic feeder of the furnace with concentrates,
or dry, crushed pyrites, or other ores, by means of a spiral carrier 33, which
discharges directly into the hopper 30, as shown in Figure 3. The roasted ore,
when discharged by way of the outlet chute 8, falls by its own gravity into a
receiver 34, from which it is taken by spiral carriers 35 to a plurality of tanks or
vats 36. These vats, which are duplicates one of another, have filtering layers 37,
at bottom, formed of any suitable material, and below said filtering layers and the
perforated false bottoms 37ª, on which they rest, are communicating chambers 38,
which receive the filtered liquid. In a convenient position above the vats are
arranged reservoirs 39, lined with lead, or other suitable material, and containing a
chlorine solution, containing about one per cent. of free chlorine. When the tanks,
or vats 36, are filled with roasted ore by the spiral carriers 35, they are closed by a
cover which is applied with care, and the chlorine solution is allowed to run through
the mass of roasted ore. The gold is dissolved thereby, or, to speak more
accurately, is transformed into a chloride, which is readily soluble in water.
chloride solution is passed through the filtering material 37 into the communicating
chambers 38, from which, the said solution is conveyed by a pipe 40 to a series of
precipitating vessels 41, in which the precious metal, or metals, are eliminated.
The passage of the chloride solution through the filtering material 37 may be
expedited by means of atmospheric pressure a pipe 42 being arranged to connect
the series of chambers 38 with a pump 43, by which the air is withdrawn from said
chambers. The normal atmospheric pressure on the solution in the tanks, or
vats 36, forces said solution through the filtering material, as the communicating
chambers 38, are tightly closed against all access, save through the filtering
material 37.
This
The precipitating vessels 41, one of which is shown in detail in Figure 5, contain
chips, or particles of aluminium, or zine, resting on perforated diaphragms near the
lower ends of said vessels. The outlet 44 to each vessel is above the mass of
aluminium or zinc particles, and they are connected in series, so to speak, by
pipes 45 leading from said outlets to the inlets 46, which are below the perforated
diaphragms. The pipe 40 enters the inlet of the first vessel 41, and a pipe 47
extends from the outlet of the last vessel over a tank 48, which receives the fluid
after it has traversed the vessels 40.
The gold contained in the chloride of gold solution after passing through the
filter, is precipitated by the aluminium particles or by the zinc and settles thereon

page_text: in the form of a fine powder. Being detached by the continuous upward current,
the precipitated particles work their way downward by their own gravity and
collect in the lower ends of the vessel's 41.
In some cases it may be necessary to allow the chlorine to act upon the ore for a
longer time than that occupied by the chlorine solution' in percolating the mass of
ore in the tanks, or vats 36, and for this purpose the connection between the tanks
or vats 36 and the chambers 38 may be closed by any convenient means for instance
by inserting plates between the filtering medium 37 and the false bottom 37* or
beneath the false bottom 37" so as to close the passage therethrough of chlorine
solution and so the chlorine solution may be retained in the tanks as long as may
be necessary. This treatment effects a considerable économy in the consumption of
chlorine.
The tank 48 contains a mass of chips, turnings, or particles of aluminium, by
which any small quantities or traces of gold still remaining in the solution after
coming from the precipitating vessels 41, are collected and saved.
Should the ore contain free gold it may be obtained by allowing the tailings from.
the tanks 36 to run upon amalgamated copper plates 49.
After chlorination, the coarse gold which is not dissolved by the chlorine solution
is so thoroughly cleansed by the action of said solution, that it can be caught and
retained by the copper-amalgamated plates, upon which the tailings are discharged,.
as last described.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner is to be performed I declare that what I claim is :-
1. The process herein described for desulphurizing refractory ores, said process
consisting in arranging the ore in a series of quantities each of which is a step
nearer the fire, roasting part of the whole number of quantities in direct contact
with the fire, and simultaneously roasting the remaining number of quantities
without access of fire, and periodically advancing the whole series a' step, whereby
one of the separate quantities is discharged from and another is brought into the
fire, while all the quantities in one part of the series are brought a step nearer the
fire, substantially as described.
2. The process described for desulphurizing refractory ores, said process consisting
in arranging the ore in a series of separate quantities, separating several of said
quantities from the remaining quantities, roasting the entire series simultaneously,
part of the whole series with, and the other part without direct contact with the
fire and transferring the entire series step-by-step to bring the quantities in one
part into and through the fire and out of the furnace, and to advance the quantities
in the other part, toward the fire and bring them successively into the first series,
substantially as described.
3. The process described for the complete desulphurization of refractory ores by
a single, continuous treatment, said process consisting in arranging the ore in
separate quantities one above the other, roasting those quantities above a given
point without access of fire, and those below said point in the presence of both air
and fire, periodically transferring the several separate quantities of ore a step
downward whereby they successively approach, enter, and ultimately pass through
the fire and out of the furnace, and periodically supplying quantities of fresh ore at
the top, substantially as described.
4. The process described, which consists in arranging separate quantities of ore
one above another, roasting part of said quantities without contact with fire and
the remainder with contact of both air and fire, transferring the separate quantities
of ore periodically a step downward to bring them successively nearer to and into
the fire, carrying the separate quantities of said ore through the fire and out of the
same, transferring the roasted ore to a vat, flooding it with a chlorine solution,
filtering and finally precipitating the chlorides of gold by aluminium, substantially
as described.
5. A furnace for desulphurizing refractory ores, said furnace having a series of
B

page_text: .horizontally movable soles arranged one above another over the fire-chamber of a
furnace, a series of rakes arranged over each sole and pivotally connected to each
other, below their pivotal supports, and to a pivoted rod capable of swinging
outwardly, one of said soles between the top and bottom being adapted to cut off
the upward passage of air and products of combustion, and means for conducting
the latter from the space beneath said sole to the chimney, substantially as
described.
6. A furnace for desulphurizing refractory ores, the same comprising a series of
soles arranged one above another in a closed chamber above the fire-chamber, one
of said soles at or near the middle of the series being adapted to cut off the upward
passage of air and products of combustion, means for drawing said soles out of and
into said chamber independently; a series of rakes arranged over each sole and
connected to each other and to an arm in such manner as to turn on pivotal
, supports when the soles are drawn into the chamber and to stand rigidly vertical
when said sole is drawn out and external pipes connecting the space beneath the
middle sole with the chimney substantially as described.
7. In a furnace for desulphurizing refractory ores, the combination with a series
of soles arranged one above another in a chamber over the fire-chamber, their edges
resting on rolls mounted on fixed axes in recesses in the walls, of means for drawing
said soles out of and into said chamber in opposite directions alternately, supple-
mental supporting rolls mounted on extension side-walls, rakes arranged over each
sole and connected together and to a pivoted external arm, a series of movable
rakes over a fixed sole at the bottom of the fire-chamber, an outlet chute and
an automatic feeder for supporting ore at the top, one of the soles at or near
the middle of the series being adapted to cut off. the passage of air and products
of combustion, and deflect the same into external passage, substantially as
described.
8. The combination with a desulphurizing furnace having horizontally movable
soles arranged in a vertical series in a chamber over the fire-chamber, of means for
drawing said soles independently out of and into said chamber, external pipes
connecting the chimney with the space beneath a sole at or near the middle of the
series, a feeder, a chlorination tank having filtering material in its bottom and
receiving the roasted ore from the furnace, and reservoirs containing a solution of
chlorine arranged above the level of the tank, substantially as described.
9. The process described for recovering gold from its ores, the same consisting in
arranging the ore in separate quantities removed, successively, a step farther from
the fire, separating part of the whole number of quantities from the other part,
roasting the whole series by a single fire simultaneously, one part with and the
other part without direct access of fire, advancing the separate quantities periodi-
cally to bring them nearer to, into, through, and out of the fire, treating the roasted
ore with a chlorine solution, filtering, precipitating the gold from the chloride
solution by aluminium, and recovering the coarse gold present, in the tailings by
amalgamation substantially as described.
Dated this 5th day of March 1805