Year: 1886

page_text: Date of Application, 21st Sept., 1886.
Complete Left, 22nd June, 1887.
Complete Accepted, 29th July, 1887.
I BENJAMIN HOWARTH THWAITE of 37 Victoria Street Liverpool in the County of
Lancaster Civil Engineer do hereby declare the nature of this invention to be as
follows:
--
My present invention principally consists in improvements on my prior invention
for which a patent was granted to me dated the 25th day of September 1885 and
numbered 11,402.
Instead of feeding the decarbonising cylinder with the metal direct from a cupola or
blast furnace-I may carry the metal, from cupola or blast furnace, in a ladle-and
pour the metal into the mouth of decarbonising cylinder which is attached to an open
hearth steel furnace of the Siemens or any other type-and I arrange said
decarbonising cylinder in plan so as to be adaptable to the contracted superficial space
available at the side of existing openhearth furnaces-In order to heat the
decarbonising cylinder I may utilise the producer gas from the said openhearth'
furnace or I may utilise the sensible heat of the products of combustion from the said
open hearth furnace to raise the temperature of the decarbonising cylinder-to a steel
melting degree. I may mount the decarbonising cylinder along with, or independently
of a ladle on a carriage-running on rails parallel with the line of open hearth
furnaces- -so that the molten or fluid pig metal may be fed-and be decarbonised in
its passage through decarbonising cylinder into the different openhearth steel furnaces
as desired.
On the same carriage carrying decarbonising cylinder or converter and ladle I may
fix the air blowing apparatus with machinery for actuating same.
The air blast pipes on the side of cylinder I provide with regulating valves-having
fireclay plugs.
In order to deoxidise and free the foreign impurities from the iron ores I may use
for the decarbonising process, I adopt a modification of the apparatus shewn in
figures 3 4 5 and 6 of my patent dated September 25th 1886 and numbered 11,402.
I grind the iron ore-preferably to the size of beans, and feed it into the cylinder
by means of a specially arranged feed hopper-and through an orifice so inclined that
the ore is shot on to the bottom of the revolving or oscillating cylinder.

page_text: I make the lining of the cylinder either of refractory material with radiated fins or
shelves locked on all sides to the other brickwork or I may use a water lined
cylinder with internal projecting ledges-by which the pulverised ore is continually
revolved and falls across the deoxidising flame which traverses the inside of the
cylinder.
The cylinder is placed slightly inclined-about 1 in 18-so that the material
gradually gravitates through it to the lowest end-from which it falls into a pocket
connected either to an open hearth furnace or into a shoot from which I lead it to a
crushing mill, afterwards separating the reduced spongy metal from its impurities by
gravity or I may separate the metal from the non-metallic elements by means of
magnetic affinity.
In order to remove the deoxidised ore as it falls from the lowest end of the cylinder-
I provide fins which revolve with the cylinder-and remove the reduced ore from
cavity at the lower end of the cylinder as fast as it falls therein.
In the other modification of the apparatus shewn in figures 5 and 6-in my patent
number 11,402 A.D. 1885-I simply shake oscillate or only partly revolve from side
to side the cylinder-which is preferably inclined at an angle equivalent to a rise of
1 in 22-As the cylinder oscillates the deoxidised material gradually gravitates
through it.
I may connect to an ordinary Siemens or other type of openhearth furnace-one
cylinder for decarbonising-and another for deoxidising-the operation of purification
would then be as follows, I first fill the hearth of open hearth steel furnace-with the
requisite quantity of molten pig iron metal which metal has passed through
decarbonising cylinder, and has been almost entirely decarbonised.
During this period the character of gaseous combustion is an oxidising one-1 then
feed the iron ore preferably pulverised into deoxidising cylinder-in this instance
providing a catch pit and grid arrangement for separating any impurities that may
have gravitated along with the reduced and spongy metal.
During the progress of the iron ore through deoxidising cylinder-the character
of combustion is a deoxidising one-and the producer gas supply is increased in
pressure so that by the velocity of the reducing gases through the cylinder the
small non metallic particles from the ore are carried forward into a catch pit-provided
in the flue connecting cylinder with chimney.
The spongy reduced ore-is fed into the bath of metal-and neutralises or reduces
the proportion of carbon contained therein in proportion as it, the ore, has been
deoxidised in passing through the deoxidising cylinder.
When using a Cupola of the Stewart Rapid Type, I may apply a blast of air to the
metal as it flows from cupola--such blast of air passing through specially devised
perforated refractory blocks-placed immediately under the flow of metal, as it issues
from cupola into collector-by this arrangement I partially decarbonise the metal
before it enters the decarbonising cylinder.
Dated this 20th day of Santamber 1886

page_text: COMPLETE SPECIFICATION.
Purification of Iron Ore and Fluid Iron Metal and Apparatus
therefor.
I BENJAMIN HOWARTH THWAITE of 37 Victoria Street Liverpool in the County of
Lancaster Civil Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement :-
My present Invention principally consists in improvements on a prior Invention for
which a patent has been granted to me dated the 25th day of September 1885 and
numbered 11,402.
I will now briefly describe the nature of my said Invention, as illustrated by the
accompanying two sheets of drawings which are intended to form part of this
specification-But I wish it to be clearly understood that I do not confine myself to
the exact details shewn, as they may be modified without departing from the nature
of my said Invention.
The same figures, wherever repeated refer to the same or similar respective parts.
Referring to figures 1 and 2 Sheet A of drawings Fig. 1 is a plan and figure 2 is
a section and side elevation, shewing one arrangement of my Invention when applied
to existing open hearth, Siemens, or other type of furnaces, where the space available
at the side thereof, does not allow of the arrangement as shewn in figures 123 and 4
in sheet 1 of drawings accompanying the specification of my patent numbered 11,402
―(1885).
a is the cupola, preferably of the Rapid type, with its Receiver b, preferably
placed at the end of the steel melting shop, an overhead railway c is provided to
carry ladle d. which carries the melted pig iron from Cupola Receiver to the mouth e
of cylindrical converter f. through which the metal flows to the open hearth
furnace g.
The air blast is supplied to converter f by means of pipes h.
Part of the products of combustion of the gaseous fuel, is led from open hearth
furnace through cylindrical converter f, the gaseous flow being induced by the
refractory lined connections t, with their controlling and reversing valvesj, or the same
connections may be arranged-to lead gas from gas ports to end of converter,
ignition of gas being effected at the metal receiving end of converter and the
combustion passing through converter towards furnace.
The valves are reversed along with the reversal of the gas and air valves of
furnace.
When the space at the side of the open hearth furnace is not available or convenient
for the aforesaid arrangement, or the one in which the cylindrical converter is placed
in relation to the furnace at an angle other than a right angle-and thus--
appropriates the area of ground space required-1 place the ladle carrying railway,

page_text: immediately over the open hearth furnaces, and place the converter cylinder either
vertically or but slightly inclined from the vertical, in the centre of the roof of the
furnace.
I prefer in this modification, to make the converter cylinder cone shaped, and
provide it with an annular air cavity or outer casing for the purpose of providing an
uniform supply of air to the air supply perforations or air jet holes provided in inner
refractory lining-These air supply perforations I so arrange that the direction of
the air jets is descensional, and thus forces the metal and products of conversion
descensionally onto the hearth of furnace I may provide a special lump of refractory
material on bed of furnace to receive the impact of the metal as it falls from mouth
of converter.
Figure 3 shews a part cross section of open hearth furnace, the overhead railway
and ladle.
Figure 4 shews an enlarged detail of vertical cylinder converter and a part of open
hearth furnace roof.
k is the vertical converter cylinder, l. air jet perforations in refractory lining m ; air
is supplied from air cavity n.
d is the ladle and is the air blast supply pipe.
A hinged or other form of mechanically attached refractory cover o is used for
closing mouth of cylinder after the metal is charged therein.
The cylinder converter may have a gas pipe attached to its upper end to raise the
temperature of converter to a high degree.
The overhead railway and position of converter in plan is shewn by dotted lines
on figure 1.
Another modification is shewn in figure 5. In this arrangement the ladle railway
is over the furnace but the metal from ladle is fed into a refractory lined shoot p.
from which it falls into a shoot converter cylinder q., into and through which, the
metal flows into open hearth furnace.
The metal as it falls into converter is caught by a jet, (or jets) of air g' that blows
the metal into the hearth of furnace and thus partially oxidises it.
Figure 6 shews a section of the Cupola Receiver provided with one or more air
jet holes, immediately under a special block formed of refractory material-During
the flow of metal from Cupola into its Receiver, the air blast is turned on to the
aforesaid air jet holes and the metallic impurities are thus partially oxidised.
Figure 7 shews my Invention applied to the purification of iron ores.
After the iron ore has passed through the revolving calcining and reducing
cylinder B, described more fully further on, and from the outlet end of which, it falls
in the form of reduced spongy metal into a fine B W G. Riddle cylinder C by which
the metal and its impurities are properly shaken and the finer particles of the metal
and earthy and other impurities fall into a trough Ein which there revolves a
magnetised Archimedian screw F to which the finer metal particles become attached
by magnetic attraction, the earthy particles fall through the perforations in trough, on
to a lower grid, which separates the particles more completely, and from which the
earthy impurities can be easily removed.
GG are the terminals of the electric conductors.
The electro-motive power is derived either from a dynamo, or from any other
electric producing source.
As soon as sufficient particles of metal has become attached to the Archimedian
screw it is demagnetised, and the metal is then removed by the revolution of the
screw, and the collection of the metal particles in a lower trough or chamber can be
effected.
H is the driving shaft of the riddle cylinder from which the archimedian screw
shaft is actuated.
Figure 8 is a section of the Riddle Cylinder and of the magnetised separating
archimedian screw.
Figure 9 shews a side elevation of the arrangement of my Invention for the
purification of iron ores applied in connection with a blast furnace D.

page_text: The waste gases from blast furnace, with the addition of gaseous fuel from a
Thwaite Gas Producer, in sufficient volumes to convert the chemical nature of the
blast furnaco gases onto a thoroughly reducing one, pass along the fluo I through
regulating valve J into the combustion chamber B₁ of Calcining Revolving
Cylinder B.
The reduced spongy metal falls from mouth of Calcining Revolving Cylinder B,
into the riddle cylinder and magnetic separator and finally falls into a shoot K
delivering into mouth of blast furnace.
The worm shaft that drives the Calcining Revolving Cylinder B actuates the riddle
cylinder shaft H.
The Caleining Revolving Cylinder is fed with ore by means of a mechanical feed
hopper L.
A platform M is provided for the accumulation of the ore required to be purified.
Fig. 10 shews another modification of the magnetic arrangement for separating the
particles of spongy metal from the impurities-B is a section of Calcining Revolving
Cylinder which may be water lined and from which the reduced spongy metal and
earthy impurities fall into a shoot N, which delivers them to the crushing rollers O.
The crushed metal and impurities fall through a shoot P the upper side of shoot
being so constructed as to be strongly magnetic.
The large spongy pieces along with the earthy and other impurities, pass through
the shoot, whilst the finer metallic impurities, are attached to the magnetised surfaces Q
of the shoot.
The large spongy masses are separated from the earthy matters by being passed
through a riddle cylinder, but this latter operation can be effected before the materials
are passed through the crushing rolls.
On sheet B of drawings figures 10, 12, 13 and 14 shew the general arrangement of
Reducing Calcining Revolving Cylinder arrangement.
Fig. 11 is a longitudinal section, figure 12 an end elevation figure 13 a general
plan and figure 14 is a section of Revolving Calcining Cylinder.
In a simpler arrangement the ore may be fed into mouth of cylinder by gravity
but I generally prefer the arrangement of screw feed R.
The ore falls into the Calcining Revolving Cylinder which is provided with
refractory linings, and projecting horizontal shelves S, the shelves may be arranged
longitudinally in cork screw configuration-The cylinder may however be simply
water jacketted.
The ore gradually gravitates by the slow revolution of the Revolving Cylinder
owing to the longitudinal axis of the cylinder being slightly inclined from the
horizontal.
The ore in its passage through revolving cylinder is subjected to a reducing nature
of combustion.
The reduced ore,
in a spongy metallic condition falls into a deep depositing
chamber T, on to the perforated inclined plate or grid U which turns on a hinge U₁
and can be actuated by a handle U until it is at the position U³ to enable the
materials to be withdrawn.
When the spongy metal is required for the dilution of the metal in the open hearth
furnace, it is pushed forward-by inanual labour through doors V.
The gases and products of combustion, to which additional air may be supplied for
the complete combustion of the gases as they leave the Calcining Revolving Cylinder,
pass into the regulating and reversing valve W, and along refractory lined
connections X into recuperator or heat accumulating stoves Y, in passing through the
stoves Y, any suspended oxide dust is deposited, and the sensible heat of the gases, and
that resulting from the heat of completion of combustion is accumulated.
The gases finally escape by connections Z and reversing valves Z Z into chimney
ZZZ. The air from Roots blower or other type of air inducing machine, is forced
into valve W and passes into and through corresponding connections and through a
recuperator stove, which has been heated by the passage through it during a prior
period of the products of combustion, the air leaves the recuperators highly heated,

page_text: and is diverted by valve Z Z into mains CC, which deliver it to the air tuyeres at
each end of the open hearth furnace, where it supports the combustion of the gaseous
fuel issuing from the gas tuyeres' D D The gaseous fuel may be produced either
from solid or liquid hydrocarbons.
.
g
The initial combustion of the gaseous fuel occurs in the open hearth furnace
simultaneously at each end, the flame passes through depositing chamber T, into
Calcining Revolving Cylinder.
During the period the ore is being reduced, the nature of combustion is of course a
deoxidising one, but on the completion of, and during the charging of the fluid pig
metal into furnace the nature of combustion is an oxidising one.
The pig metal is further oxidised and purified in its passage through converter
cylinder fixed in roof of furnace as hereinbefore described.
The advantages derivable from the use of my Invention for the purification of iron
ores and fluid iron metal may be enumerated as follows-
The more convenient adaptation of my Invention, for the purification of pig iron
metal, to existing open hearth steel furnaces.
My Invention applied to the purification of iron ores-permits the reduction of the
ore when in a finely divided condition-such as for example-the magnetic oxide or
titaniferrous sand-found on the shores of New Zealand.
It allows of the use of ores of the lowest class, or those having an extremely low
percentage of iron.
In the application of my Invention to ordinary iron ores, the advantages are-that
a great percentage of the earthy and other impurities are separated from the metal
during its reduction-and at a temperature of a 1000° Fah., less than that absorbed
and required in the blast furnace. consequently the spongy reduced metal can be
charged into the blast furnace with a less proportion of limestone, and the heat that is
absorbed in raising the temperature of the earthy and other foreign impurities to the
high temperature of fusion and fluxation, is saved-and there is also a reduced waste
of iron passing away with the slag.
The spongy metal can be used for diluting the charge of pig metal in open hearth
steel furnace, reducing the cost of this operation considerably-or the spongy reduced
metal can be balled and converted in the puddling furnace into forged metal.
•
The method of separating the earthy impurities from the spongy metal by
magnetic affinity is an effectual and inexpensive one.
Having now particularly described and ascertained the nature of my said Invention
and in what manner the same is to be performed, I declare that what I claim is,
1st. The method of purifying fluid iron metal substantially in the manner and as
herein shewn and described.
2nd. The method of purifying iron ores substantially in the manner and as herein.
shewn and described.
3rd. The form of Converter Cylinder-as shewn in figures 1 2 3 4 5 and 6 Sheet A
of drawings in its application to open hearth steel furnaces.
4th. The arrangement of Calcining Revolving Cylinder with its Recuperator Stoves
Valves and Connections-and Depositing Chamber-substantially as herein shewn and
described.
5th. The arrangement for separating the spongy iron metal from its earthy and
unreduced mineral impurities in its combination with Caleining Revolving Cylinder
and Crushing Rolls, substantially as herein shewn and described.
Dated this 20th day of June 1887.