IMPROVEMENTS IN SMELTING. COPPER ORES, CUPREOUS PYRITES, AND ORES CONTAINING A MIXTURE OF SULPHIDES OF COPPER AND IRON WITH OTHER SULPHIDES, SUCH AS ZINC, LEAD, ANTIMONY, ARSENIC, AND OTHER SULPHIDES, AND THE PRECIOUS METALS
Year: 1879

page_text: ETTERS PATENT to William Henderson, of Irvine, Ayrshire, North Britain,
Manufacturing Chemist, for the Invention of "IMPROVEMENTS IN SMELTING.
COPPER ORES, CUPREOUS PYRITES, AND ORES CONTAINING A MIXTURE OF
SULPHIDES OF COPPER AND IRON WITH OTHER SULPHIDES, SUCH AS ZINC, LEAD,
ANTIMONY, ARSENIC, AND OTHER SULPHIDES, AND THE PRECIOUS METALS;. ALSO
IN THE RECOVERY OF THE GREATER PROPORTION OF THE SULPHUR FROM THESE
ORES OR MIXTURES OF ORES, AND IN THE CONSTRUCTION OF APPARATUS FOR
THESE PURPOSES; ALSO FOR IMPROVEMENTS IN SUPPLYING THE BLAST OF AIR
MIXED WITH STEAM NECESSARY FOR THESE OPERATIONS, AND IN THE LINING
OF AND OTHER CONSTRUCTION OF THE FURNACES NECESSARY FOR THIS PURPOSE,
AND THE SEPARATION OF THE SUBLIMED OXIDES OR SULPHIDES FROM THE
SUBLIMED OR PRODUCED SULPHUR."
PROVISIONAL SPECIFICATION left by the said William Henderson at the
Office of the Commissioners of Patents on the 12th March 1879.
"
WILLIAM HENDERSON, of Irvine, Ayrshire, North Britain, Manufacturing Chemist.
IMPROVEMENTS IN SMELTING COPPER ORES, CUPREOUS PYRITES, AND ORES CON-
TAINING A MIXTURE OF SULPHIDES OF COPPER AND IRON WITH OTHER SULPHIDES,
SUCH AS ZINC, LEAD, ANTIMONY, ARSENIC, AND OTHER SULPHIDES, AND THE PRECIOUS
METALS; ALSO IN THE RECOVERY OF THE GREATER PROPORTION OF THE SULPHUR
FROM THESE ORES OR MIXTURES OF ORES, AND IN THE CONSTRUCTION OF APPARATUS
FOR THESE PURPOSES; ALSO FOR IMPROVEMENTS IN SUPPLYING THE BLAST OF
AIR MIXED WITH STEAM NECESSARY FOR THESE OPERATIONS, AND IN THE LINING
OF AND OTHER CONSTRUCTION OF THE FURNACES NECESSARY FOR THIS PURPOSE, AND
THE SEPARATION OF THE SUBLIMED OXIDES OR SULPHIDES FROM THE SUBLIMED OR
PRODUCED SULPHUR."
A process has been proposed by Mr. John Hollway and patented by him as per
Specifications No. 5001878 and No. 11311878, in which he uses the sulphur as fuel
by injecting air by a blowing engine at a pressure of at least 10lbs on the square
inch. The blast has hitherto been used cold, but provision is made for using a hot
blast if necessary.

page_text: «
"
:-
Hitherto the experiments have been confined to the use of the Bessemer plant,
and the whole of the sulphur has been allowed to escape. In his Final Specifi-
cation he proposed to use fixed convertors or modifications of blast furnaces, also
using super-heated steam. His description in his Final Specification is in these
words "I employ a hot blast of air when I desire to operate on a large
proportion of metallic oxides as compared with the pyrites and sulphides
employed, and when I desire to obtain a large proportion of free sulphur in lieu
"of employing all the surplus heat for treating metallic oxides I introduce super-
"heated steam into the furnace in addition to the air, which latter I introduce as
a hot blast and in sufficient quantity to compensate for the reduction of the
temperature by the steam employed, and also to produce enough heat to expel as
"free sulphur one equivalent, that is, about one half of the sulphur originally com-
"bined with the iron in the pyrites introduced at the upper part of the furnace.
By thus employing superheated steam I obtain free sulphur expelled from the
pyrites, whereby protosulphide is formed and an additional quantity of sulphur
"liberated from the residual sulphides."
"
"
Mr. Hollway's process to be useful must save all the sulphur given off either as
sublimed sulphur or liberated in the state of sulphurous acid or any other of the
oxides of sulphur, or as sulphuretted hydrogen; and the apparatus in use must be
simple, cheap, lasting, and easily repaired, and to obviate and provide for all or
most of these objections and difficulties is the object of the present Invention, and
to effect these improvements I proceed as follows:
The furnace in which the smelting of the mixture of siliceous copper ores with
the requisite mixture of cupreous pyrites takes place should be in the form of an
ordinary blast furnace. This furnace need not in ordinary cases be of a great height
as the mixed sulphides and silicious ores are in the absence of intermixed fuel
easily smelted.
For the same reason the crucible or hearth and the boshes need not be too much
contracted. I prefer to have a furnace with the hearth, crucible, and part of the
boshes to the extent of two feet above the tuyeres movable, or rather removable.
The whole of the upper part of the furnace, including the stack and the upper
part of the boshes, I support on strong pillars, either of masonry or cast iron, and
these are built in the usual way, as is well understood in building blast furnaces.
The lower part I prefer to have separate and in one piece, including the tuyeres,
and two feet above them. The outer casing of this should be made of boiler plate
and bands, double rivetted, with punched or drilled holes of 3/8 inch diameter, about
9 to every square foot of outer surface. This is the outer shell, which should con-
tain the hearth dam, crucible, and the boshes, to two feet above the entrance of the
tuyeres, and give space for 3 feet of solid hearth and two feet of lining all round to
meet exactly the fire brick lining two feet above the tuyeres.
It has been very difficult to find a lining to withstand the action of the ferrous
ortho-silicates. It destroys ganister and firebricks of any kind rapidly.
Bricks made of caustic lime have been proposed, but as in the working of a blast
furnace with a charge of sulphides of iron and copper the upper slags must be at
all times charged with sulphides of the metals, which will form with lime the
easily fusible sulphide of calciun. I construct my hearth, crucible, and two feet
above the boshes of solid carbon, which cannot melt and cannot be acted upon by
silicates of iron, except to produce a thin film of,wrought iron on its surface.
.I prepare this removable part of the furnace in the following manner :-
Having the perforated wrought iron casing as previously described, after laying
and baking or coking the hearth. three feet thick, which may be constructed on a
separate ring bolted to the superstructure, with dam and slopes for tapping clear
and dry, I construct on the top of this the crucible and boshes, or part of them,
as previously described, together with the inclined tuyere holes on the necessary
slant to effect my object. A cast iron core in segments of the shape of the intended
interior of the furnace is now placed in the centre of the hearth and the prepared
carbon mixture rammed in.

page_text: Tapered cast iron moulds to represent the tuyeres being imbedded in the rammed
carbon, having projections outside the wrought iron shell, whereby they can be
withdrawn when the whole mass has been thoroughly coked. I prepare the carbon
lining in the following manner:
I take selected and very hard burnt coke of the best quality and heat it up to
about 300° F., so as to expel every trace of moisture and grind it in a pan or
mortar mill to size of very coarse sand or fine gravel. I then add hot coal tar,
which has been well boiled; and to keep all hot I place a fire or fires under the pan
of the mill only; so much tar is added as will slightly soften the mass, which should
be sufficiently dry to ram solidly with an iron rammer with a smooth face without
adhering to the tool. The iron core should also be perforated with small holes like
the outer casing and coated with whitewash on the side next the carbon to prevent
it adhering in the after process of baking or coking. The whole structure is then
run on an iron trolly into an oven or furnace constructed for the purpose and
gradually brought up to a cherry red heat and kept at this heat until the tar is
thoroughly coked. This should not be hurried.
The process is complete when jets of flame cease to rise from the surface or come
through the perforations. When sufficiently cold to handle, this portion of the
furnace is now ready (when the core is withdrawn) to be fixed in its place. The
carbon lining which forms the hear: h, the crucible, and part of the boshes of the
furnace may also be formed by baking or coking blocks forming segments of the
several parts and coked in perforated cast iron moulds, the cement, consisting of
ground coke and tar finer ground and softer, and trusting to heating up of the '
furnace to produce the necessary heat to coke all the blocks into one solid mass.
This solid carbon can be hewn into any shape like moderately soft sandstone, and
any faults or bad joints can be caulked with the original material, which adheres
and cokes readily on the application of heat. Having prepared my furnace and
made all ready for a start by heating up with coke slowly I must next describe
how I arrange the tuyeres and produce the blast. In order to obtain all the
sulphur and sublimates that are distilled, sublimed, or evolved from the furnace as
oxides, and particularly the sulphur when it must be disengaged as sulphurous acid
or other oxide of sulphur when air alone is used as the blast, I always in every
case use steam mixed with air as the blast to be projected into the molten sulphides.
I also make use of the steam on the principle of the injector to be the motive power
for introducing the air, whether cold or hot, and thereby dispensing with blowing
engines.
When I want a large quantity of air and little steam, I simply increase the
pressure of the steam; and when the reverse I reduce the pressure or keep the same
pressure and enlarge the air orifices. The object I have in view is always to
produce enough sulphuretted hydrogen to form sulphur and water or steam with
the sulphurous acid, and have no excess of either the one or the other, or have at
all times a means of producing one or other of these gases at will, as I shall describe
further on when I come to explain the condensing apparatus.
I place my lower set of tuyeres, those composed of a mixture of steam and air, on
a slant, so as to blow downwards into the molten fluid to within one foot of the
hearth, and these I call the permanent tuyeres; about two feet above them I have
another set to be used only when more heat is wanted or more sulphurous acid. The
blast from a Root's blower will be sufficient for this purpose in all ordinary mixtures
of ores, especially when pyrites rich in sulphur are to be had in large proportion.
These tuyeres should blow straight in or be slightly depressed, and when not in
use should be blocked with coal or small coke, and closed outside. The furnace
being thus equipped it should be filled with coke, which of course has a hot furnace
to go into up above the second set of tuyeres two feet and allowed gradually to
attain a full heat by natural draught, the products of combustion being allowed to
escape into the atmosphere.
The tunnel head of the furnace should be supplied with a cup and bell
arrangement; and I prefer to draw off the gases some feet-below-the-charging

page_text: place, so that there will always be a downward draught when the valve is
open and the charge being dropped. The lateral openings should also be large
and numerous, and easily got at to clean, as when ores are used containing
much lead, zinc, or arsenic, the sublimate will rapidly close up these passages. For
the same reason the descending flue to the condensors should be wide and short,
terminating rapidly in a large high brick chamber for these heavy sublimates to
deposit in.
These chambers may be more than one, according to the nature of the ores to be
smelted and the sublimates produced. From thence I prefer to carry the mixture
of sulphurous acid and sulphuretted hydrogen up and down through long narrow
chambers formed by preference of cast iron plates, the mixed gases being supplied
with steam of low pressure. The floor of these chambers is formed of concrete, and
paved with fire brick glazed and formed in ridges and furrows, so that when these
chambers gradually increase in temperature the flowers of sulphur will melt, and
run into the furrows which have tap holes through which the sulphur can be tapped
into moulds. In the chambers nearest the furnace, the sulphur may be mixed with
the more volatile sublimates, from which I separate it by melting by high pressure
steam the sublimates floating on the top of the molten sulphur, which is tapped
from the bottom of the boiler into moulds. At the end of the condensing apparatus
I place one or more large towers, which may be formed of wood and lined, and filled
with glazed bricks which are arranged across each other so as to produce numerous
pigeon holes.
The waste gases are made to ascend these towers, and are drawn off from the top
to the chimney. The towers are sur-mounted with water cisterns, and a stream of
water is thoroughly distributed over the top of the condensors, and descends
through and among the bricks to a cistern at the base, carrying with it the last
traces of sulphur.
There should be neither sulphurous acid nor sulphuretted hydrogen present in
the water in this cistern at the base, as the supply of either can be regulated at
the tuyeres by giving more steam to produce sulphuretted hydrogen, or air to
produce sulphurous acid.
By testing the water from the condensers and the gases escaping to the chimney
frequently, and altering the pressure or the volume of the steam admitted at the
tuyeres, or by increasing the air by bringing into use the upper set of tuyeres and
the blower, the proportions can at once be adjusted.
Having thus described minutely the apparatus I use, I proceed now to describe
the mode of working.
The furnace having been dried, heated, and seasoned, and all ashes cleared out, I
introduce good hard coke up to two feet or so above the upper tuyeres, and when
this has been rapidly kindled by the blast and is heated to a bright heat all
through, I commence to charge the mixed ores or ores mixed with silicious matter,
as the case may be, as rapidly as possible, until the furnace is full, maintaining all
the time about one quarter of the full blast.
As soon as the furnace is full the full blast should be put on, and charging
uninterruptedly continued as soon as the previous charge has sunk low enough to
admit another.
When treating cupreous pyrites containing 42 to 49 per cent. sulphur, and from
3 to 8 per cent. silica, I prefer to have it broken into pieces about the size of one's
fist and smaller, absolute dust, or what would pass through a quarter inch riddle
should be avoided, and if any such is used it should be placed by itself round the
outer edge of the cone, so as to rest against the walls of the furnace when the
charge is dropped.
I prefer however to grind all such smalls in a mortar mill flat out on a drying
floor, and cut them into squares (when soft) of about two inches cube.
With such ores, silica in some shape must be added to form a slag. When
working such ores at the mines where they are produced, such as in Spain, where
the production of a slag rich in iron would not be an object, and where a highly

page_text: silicious clay slate is to be had in abundance cheap on the spot, I prefer to use it as
an admixture, so as to obtain a double silicate, which is of a less specific gravity,
and more fluid than a simple silicate of iron.
Of course wherever a highly silicious copper ore can be obtained as a mixture, it
will be used to its full extent.
The slag produced should always contain at least thirty per cent. of silica, and
silica or silicious matter should be added with the raw pyrites at the top of the
furnace to obtain this result. I prefer to use it in pieces smaller than the ore, but
free from dust.
When the furnace is full of molten stuff up to the first or lower set of tuyeres,
I tap the whole contents into a prepared and lined ladle which should be as hot as
practicable, and constructed so as to tap from the bottom as is well known in the
steel trade and commonly in use. This ladle, which should be large enough to hold
the whole tapping, should be on four wheels. After standing half an hour at rest,
the lower portion should be tapped into one or more cast iron moulds so as to
secure the greater part of the regulus. The rest of the contents of the ladle should
be transferred to a reverberatory furnace large enough to hold a whole charge.
This I prefer to do through a hole in the roof about the middle of the furnace, and
the ladle is run on rails just over the hole, and the liquid charge of regulus and
slag run in.
The furnace I prefer for this operation is a gas regenerative reversing furnace,
with a solid carbon bottom, eighteen inches to two feet thick, resting on cast iron
plates and girders, with clear air space underneath the plates. This furnace
should have two tap holes, one each side, and the bed should slope down in every
direction towards these tap holes. The tap hole on one side should be a few inches
lower than that on the other. When the furnace is empty and the heat on, I
protect the bottom with a layer of sand. When the heat is up to a white heat and
the charge from the blast furnace is run in, this sand is absorbed by the slag and
clears the bottom. When it is found by feeling with an iron tool that the bottom
is quite clear and the sand is thoroughly incorporated with the slag the charge is
left at rest for half an hour; I then tap off any regulus that may remain by the
lower taphole until the slag begins to come freely. A few sand beds made roughly
with the shovel as is well known in copper smelting is all that is necessary for this
purpose. This taphole is now stopped, and the higher one on the opposite side
open when the slag may be run into sand beds or iron wagons as is found most
convenient. The bottom is again covered with a thin layer of sand and any foul
slags, the tap holes made up, and the furnace is ready for another charge from the
blast furnace. The process of tapping may be reversed, the slag may be run off
first, and then the regulus and any remaining slag cleared out last.
Whenever silica is required in any of these operations, silicious ores may be
substituted so long as the copper contained is not too great to produce too rich a
regulus or too foul a slag.
When necessary, I either superheat the steam or heat the air, or do both.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Henderson in the Great Seal Patent Office on the 12th
September 1879.
WILLIAM HENDERSON, of Irvine, Ayrshire, North Britain, Manufacturing Chemist.
"IMPROVEMENTS IN SMELTING COPPER ORES, CUPREOUS PYRITES, AND ORES CON-
TAINING A MIXTURE OF SULPHIDES OF COPPER AND IRON WITH OTHER SULPHIDES,
SUCH AS ZINC, LEAD, ANTIMONY, ARSENIC, AND OTHER SULPHIDES, AND THE PRECIOUS
METALS; ALSO IN THE RECOVERY OF THE GREATER PROPORTION OF THE SULPHUR
FROM THESE ORES OR MIXTURES OF ORES, AND IN THE CONSTRUCTION OF APPARATUS
'FOR THESE PURPOSES; ALSO FOR IMPROVEMENTS IN SUPPLYING THE BLAST OF AIR
MIXED WITH STEAM NECESSARY FOR THESE OPERATIONS, AND IN THE LINING OF AND
OTHER CONSTRUCTION OF THE FURNACES NECESSARY FOR THIS PURPOSE, AND THE
SEPARATION OF THE SUBLIMED OXIDES OR SULPHIDES FROM THE SUBLIMED OR
PRODUCED SULPHUR."
A process has been proposed by Mr. John Hollway, and patented by him, as per
Specifications No. 5001878 and No. 11311878, in which he uses the sulphur as fuel by
injecting air by a blowing engine at a pressure of at least 10 lbs on the square
inch.
The blast has hitherto been used cold, but provision is made for using a hot blast
if necessary.
Hitherto the experiments have been confined to the use of the Bessemer plant,
and the whole of the sulphur has been allowed to escape. In his Final Specification
he proposes to use fixed convertors or modifications of blast furnaces also using
superheated steam.
«
"
His description in his Final Specification is in these words:-" I employ a hot
blast of air when I desire to operate on a large proportion of metallic oxides
as compared with the pyrites and sulphides employed, and when I desire to
"obtain a large proportion of free sulphur, in lieu of employing all the surplus heat
"for heating metallic oxides, I introduce superheated steam into the furnace in
" addition to the air, which latter I introduce as a hot blast and in sufficient
quantity to compensate for the reduction of the temperature by the steam
employed, and also to produce enough heat to expel as free sulphur one equiva-
lent, that is, about one half of the sulphur originally combined with the iron in
" the pyrites introduced at the upper part of the furnace. By thus employing
superheated steam I obtain free sulphur expelled from the pyrites, whereby proto-
sulphide is formed, and an additional quantity of sulphur liberated from the
"residual sulphides.'
"
"
"
"
"
Mr. Hollway's process to be useful must save all the sulphur given off either as
sublimed sulphur or liberated in the state of sulphurous acid or any other of the
oxides of sulphur, or as sulphuretted hydrogen, and the apparatus in use must be
simple, cheap, lasting, and easily repaired, and to obviate and provide for all or
most of these objections and difficulties is the object of the present Invention, and
to effect these improvements I proceed as follows:-
The furnace in which the smelting of the mixture of cupreous pyrites with the
requisite mixture of silicious copper or other ores or silicious or argilaceous matter
takes place should be in the form of an ordinary blast furnace. This furnace need
not in ordinary cases be of a great height, as the mixed sulphides and silicious ores
are in the absence of intermixed fuel easily smelted. For the same reason the
crucible or hearth and the boshes need not be too much contracted. I prefer to
have a furnace with the hearth or crucible and part of the boshes to the extent of 5
two feet above the tuyers movable, or rather removable. The whole of the upper
part of the furnace including the stack and the upper part of the boshes I support
on strong pillars either of masonry or cast iron, and these are built in the usual
way, as is well understood in building blast furnaces.

page_text: The lower part I prefer to have separate and in one piece including the tuyeres
and two feet above them.
The outer casing of this should be made of boiler plate and bands double rivetted
with punched or drilled holes of 8th inch diameter, about 9 to every square foot of outer
surface. This is the outer shell, which should contain the hearth, dam, crucible, and
the boshes to two feet above the entrance of the tuyers, and give space for 3 feet of
solid hearth and two feet of lining all round to meet exactly the fire brick lining
two feet above the tuyers. It has been very difficult to find a lining to withstand
the action of the ferrous orthosilicates. It destroys ganister and fire bricks of any
kind rapidly. Bricks made of caustic lime have been proposed, but as in the
working of a blast furnace with a charge of sulphides of iron and copper,
the upper
slags must be at all times charged with sulphides of the metals, which will form
with lime the easily fusible sulphide of calcium.
I construct my hearth, crucible, and two feet above the boshes of solid carbon,
which cannot melt and cannot be acted upon by silicates of iron, except to produce
a thin film of iron on its surface.
I prepare this removable part of the furnace in the following manner :-
Having the perforated wrought iron casing, as previously described, after laying
and baking or coking the hearth three feet thick, which may be constructed on a
separate ring bolted to the superstructure, with dam and slopes for tapping clear
and dry, I construct on the top of this the crucible and boshes, or part of them, as
previously described, together with the inclined tuyere holes on the necessary slant;
to effect my object a cast iron core in segments of the shape of the intended interior
of the furnace is now placed in the centre of the hearth, and the prepared carbon
mixture rammed in, tapered cast iron moulds to represent the tuyeres being
imbedded in the rammed carbon, having projections outside the wrought iron shell,
whereby they can be withdrawn when the whole pass has been thoroughly coked.
I prepare the carbon lining in the following manner :-
I take selected and very hard burnt coke of the best quality, and heat it up to
about 300° F., so as to expel every trace of moisture, and grind it in a pan or mortar
mill to size of very coarse sand or fine gravel. then add hot coal tar which has
been well boiled, and to keep all hot I place a fire or fires under the pan of the mill,
only so much tar is added as will slightly soften the mass, which should be
sufficiently dry to ram solidly with an iron rammer with a smooth face without
adhering to the tool. The iron core should also be perforated with small holes like
the outer casing, and coated with whitewash on the side next the carbon to prevent
it adhering in the after process of baking or coking.
The whole structure is then run on an iron trolly into an oven or furnace con-
structed for the purpose, and gradually brought up to a cherry red heat, and kept
at this heat until the tar is thoroughly coked. This should not be hurried. The
process is complete when jets of flame cease to rise from the surface or cone through
the perforations. When sufficiently cold to handle, this portion of the furnace is
now ready (when the core is withdrawn) to be fixed in its place.
.
The carbon lining which forms the hearth, the crucible, and part of the boshes of
the furnace may also be formed by baking or coking blocks forming segments of
the several parts, and coked in perforated cast iron mouids; the cement consisting
of ground coke and tar finer ground and softer, and trusting to heating up of the
furnace to produce the necessary beat to coke all the blocks into one solid mass.
This solid carbon can be hewn into any shape like moderately soft sandstone, and
any faults or bad joints can be caulked with the original material which adheres
and cokes readily on the application of heat.
Having prepared my furnace and made all ready for a start by heating up with
coke slowly, I must next describe how I arrange the tuyeres and produce the blast.
In order to obtain all the sulphur and sublimates that are distilled, sublimed, or
evolved from the furnace as oxides, and particularly the sulphur when it must be
disengaged as sulphurous acid or other oxide of sulphur when air alone is used as

page_text: the blast, I always, in every case, use steam mixed with air as the blast to be
projected into the molten sulphides.
I also make use of the steam on the principle of the injector to be the motive
power for introducing the air, whether cold or hot, and thereby dispensing with
blowing engines. When I want a large quantity of air and little steam I simply
increase the pressure of the steam, and when the reverse I reduce the pressure, or
keep the same pressure and enlarge the air orifices. The object I have in view is
always to produce enough sulphuretted hydrogen to form sulphur and water or
steam with the sulphurous acid, and have no excess of either the one or the other,
or have at all times a means of producing one or other of these gases at will, as I
shall describe further on when I come to explain the condensing apparatus.
I place my lower set of tuyeres, those composed of a mixture of steam and air,
on a slant so as to blow downwards into the molten fluid to within one foot of the
hearth, and these I call the permanent tuyeres; about two feet above them I have
another set, to be used only when more heat is wanted or more sulphurous acid.
The blast from a Root's blower will be sufficient for this purpose in all ordinary
mixtures of ores, especially when pyrites rich in sulphur are to be had in large
proportion. These tuyeres should blow straight in or be slightly depressed, and
when not in use should be blocked with coal or small coke and closed outside.
The furnace being thus equiped it should be filled with coke (which of course has
a hot furnace to go into) up above the second set of tuyeres two feet, and allowed
gradually to attain a full heat by natural draught, the products of combustion being
allowed to escape into the atmosphere. The tunnel head of the furnace should be
supplied with a cup and bell arrangement, and I prefer to draw off the gases some
feet below the charging place, so that there will always be a downward draught
when the valve is open and the charge being dropped.
The lateral openings should also be large and numerous, and easily got at to
clean, as when ores are used containing much lead, zinc, or arsenic, the sublimate
will rapidly close up these passages.
For the same reason the descending flue to the condensors should be wide and
short, terminating rapidly in a large high brick chamber for these heavy sublimates
to deposit in. These chambers may be more than one, according to the nature of the
ores to be smelted and the sublimates produced. From thence I prefer to carry the
mixture of sulphurous acid and sulphuretted hydrogen up and down through long
narrow chambers, formed by preference of cast iron plates, the mixed gases being
supplied with steam of low pressure. The floor of these chambers is formed of
concrete, and paved with firebrick glazed and formed in ridges and furrows, so that
when these chambers gradually increase in temperature the flowers of sulphur will
melt and run into the furrows, which have tap holes through which the sulphur can
be tapped into moulds. In the chambers nearest the furnace the sulphur may be
mixed with the more volatile sublimates, from which I separate it by melting by
high pressure steam the sublimates floating on the top of the molten sulphur, which
is tapped from the bottom of the boiler into moulds.
At the end of the condensing apparatus I place one or more large towers, which
may be formed of wood, and lined and filled with glazed bricks, which are arranged
across each other so as to produce numerous pigeon holes. The waste gases are
made to ascend these towers, and are drawn off from the top to the chimney. The
towers are surmounted with water cisterns, and a stream of water is thoroughly
distributed over the top of the condensors, and descends through and among the
bricks to a cistern at the base, carrying with it the last traces of sulphur. There
should be neither sulphurous acid nor sulphuretted bydrogen present in the water
in this cistern at the base, as the supply of either can be regulated at the tuyeres
by giving more steam to produce sulphuretted hydrogen or air to produce sul-
phurous acid. By testing the water from the condensors and the gases escaping to
the chimney frequently, and altering the pressure of the volume of the steam
admitted at the tuyeres, or by increasing the air by bringing into use the upper set

page_text: of tuyeres and the blower the proportions can at once be adjusted. As steam
boilers are now made to stand safely pressures of steam up to 500 lbs. per square
inch, this adjustment can easily be managed.
Having thus described minutely the apparatus I use, I proceed now to describe
the mode of working.
The furnace having been dried, heated, and seasoned, and all ashes cleared out, I
introduce good hard coke up to two feet or so above the upper tuyeres, and when this
has been rapidly kindled by the blast, and is heated to a bright heat all through, I
commence to charge the mixed ores, or ores mixed with silicious matter, as the case
may be, as rapidly as possible until the furnace is full, maintaining all the time.
about of the full blast. As soon as the furnace is full the full blast should be put
on, and charging uninterruptedly continued as soon as the previous charge has sunk
low enough to admit another.
..
When treating cupreous pyrites containing 42 to 49% sulphur, and from 3
to 8% silica, I prefer to have it broken into pieces about the size of one's fist and
smaller, absolute dust, or what would pass through a quarter inch riddle, should be
avoided, and if any such is used it should be placed by itself round the outer edge
of the cone, so as to rest against the walls of the furnace when the charge is
dropped. I prefer however to grind all such smalls in a mortar mill flat out on a
drying floor, and cut them into squares (when soft) of about two inches cube.
With such ore silicia in some shape must be added to form a slag. When working
such ores at the mines where they are produced, such as in Spain, where the pro-
duction of a slag rich in iron would not be an object, and where a highly silicious
clay slate is to be had in abundance cheap on the spot, I prefer to use it as an
admixture so as to obtain a double silicate which is of a less specific gravity and
more fluid than a simple silicate of iron. Of course wherever a highly silicious
copper ore can be obtained as a mixture it will be used to its full extent. The slag
produced should always contain at least 30 per cent. of silica, and silica or silicious
matter should be added with the raw pyrites at the top of the furnace to obtain
this result. I prefer to use it in pieces smaller than the ore, but free from dust.
When the furnace is full of molten stuff up to the first or lower set of tuyeres I
tap the whole contents into a prepared and lined ladie which should be as hot as
practicable, and constructed so as to tap from the bottom as is well known in the
steel trade and commonly in use.
This ladle, which should be large enough to hold the whole tapping, should be on
4 wheels. After standing half an hour at rest the lower portion should be tapped
into one or more cast iron moulds so as to secure the greater part of the regulus.
The rest of the contents of the ladle should be transferred to a reverberatory furnace
large enough to hold a whole charge. This I prefer to do through a hole in the
roof about the middle of the furnace, and the ladle is run on rails just over the hole
and the liquid charge of regulus and slag run in.
The furnace I prefer for this operation is a gas regenerative reversing furnace with
a solid carbon bottom 18 inches to 2 feet thick resting on cast iron plates and
girders with clear air space underneath the plates. This furnace should have two
tap holes, one each side, and the bed should slope down in every direction towards
these tap holes. The tap hole on one side should be a few inches lower than that on
the other.
When the furnace is empty and the heat on I protect the bottom with a layer of
sand. When the heat is up to a white heat and the charge from the blast furnace
is run in, this sand is absorbed by the slag and clears the bottom.
When it is found by feeling with an iron tool that the bottom is quite clear and
the sand is thoroughly incorporated with the slag the charge is left at rest for half
an hour, I then tap off any regulus that may remain by the lower tap hole until the
slag begins to come freely. A few sand beds made roughly with the shovel, as is
well known in copper smelting, is all that is necessary for this purpose. This tap
hole is now stopped and the higher one on the opposite side open when the slag.
may be run into sand beds or iron waggons as is found most convenient. The

page_text: bottom is again covered with a thin layer of sand and any foul slags, the tap holes
made up, and the furnace is ready for another charge from the blast furnace.
The process of tapping may be reversed; the slag may be run off first and then
the regulus and any remaining slag cleared out last.
Whenever silica is required in any of these operations, silicious ores may be
substituted so long as the copper contained is not too great to produce too rich a
regulus or too foul a slag.
When necesary I either superbeat the steam or heat the air or do both.
In practice it will be found preferable to run the whole charge direct and as hot
as possible from the blast furnace to the reverberatory furnace without running any
into intermediate moulds, as it has been found that no effectual separation of slag
and regulus takes place in the short time that can be allowed..
And having now described the nature of my said Invention, and in what manner
the same is to be performed; I declare that I claim,―
First. The improvements in smelting copper ores, cupreous pyrites, and ores con-
taining a mixture of sulphides of copper and iron with other sulphides, such as zinc,
lead, antimony; arsenic, and other sulphides, and the precious metals; also in the
recovery of the greater proportion of the sulphur from these ores or mixtures of
ores; and in the construction of apparatus for these purposes, substantially as
herein before described.
Secondly. The improvements in supplying the blast of air mixed with steam
necessary for these operations, and in the lining of and other construction of the
furnaces necessary for this purpose, and the separation of the sublimed oxides or
sulphides from the sublimed or produced sulphur, substantially as hereinbefore
described.
In witness whereof, I, the said William Henderson, have hereunto set my
hand and seal, this Tenth day of September, One thousand eight hundred
and seventy nine.
W. HENDERSON. (L.S.)