IMPROVEMENTS IN THE MANUFACTURE OF STEEL
Year: 1879

page_text: LETTERS PATENT to Sidney Gilchrist Thomas, of 3, Queen's Road Villas,
Queen's Road, Battersea, in the County of Surrey, for the Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF STEEL."
PROVISIONAL SPECIFICATION left by the said Sidney Gilchrist Thomas at
the Office of the Commissioners of Patents on the 19th March 1879.
SIDNEY GILCHRIST THOMAS, of 3, Queen's Road Villas, Queen's Road, Battersea,
in the County of Surrey. "IMPROVEMENTS IN THE MANUFACTURE OF STEEL."
My Invention relates to a method of accelerating the Siemens Martin or Pernot
or similar open-hearth process for the manufacture of steel or ingot-iron by intro-
ducing blast into the bath of metal through removable twyers, which are introduced
and withdrawn through the top or sides of the reverberatory regenerative gas-
furnace, in which the process is conducted.
In carrying out this Invention I use the Siemens or other regenerative gas-furnace,
and introduce the twyer either through a hole (cut) cut for the purpose in the
charging-door, which I prefer, or through an orifice made for the purpose on either or
both sides of the furnace. Or the twyer may be introduced through an orifice in the
roof of the furnace; I prefer however to introduce the twyer through the side of
the furnace or the charging-door. The twyer may be either straight or curved, but
is preferably straight. In either case it should enter the furnace at such an angle
as to enter the bath of metal near its deepest part. The twyer consists of a wrought
iron pipe of from three (3) to nine (9) inches internal diameter, protected by a very
thick casing or external pipe of a highly refractory material. If the furnace is
worked with a sand bottom, this casing should consist of excessively refractory
fireclay, or a mixture of ground silica with silicate of soda solution.
If a basic hearth is used, the casing should consist of highly burnt aluminous
magnesian lime mixed with tar, or of limestone and silicate of soda.
The extreme end of the twyer is solid, consisting entirely of the refractory
material, while the blast is delivered from a ring of horizontal orifices some two
inches from the end of the twyer, so placed that when the twyer is plunged in the
bath, all the twyer holes are at the same level, and the blast is delivered in nearly

page_text: '
horizontal currents. I prefer that the twyer holes or slits should have an oblique
direction, so as to cause the metal to circulate round the twyer.
The introduction and withdrawal of the twyer into or from the furnace may be
effected either by a rack and pinion and a telescopic joint for the blast to pass
through, or by causing the twyer to be carried on a hollow arm moving in an arc of
a circle, the blast passing through a hollow trunnion, on which the arm moves, from
the blast-main into the hollow arm, and so into the twyer.
The blast may be of the ordinary pressure.
In order to cool the twyer I introduce a second wrought-iron pipe of much smaller.
diameter into the large twyer pipe.
This pipe is open at both ends, the lower end terminating just short of the twyer
orifices, the other end passing out through an orifice in the blast pipe clear of the
furnace.
The object of this arrangement is to cool the twyer by passing through it a greater
amount of air than can be advantageously introduced into the metal.
When the twyer is withdrawn from the furnace, the orifice through which it is
introduced is of course stopped with a plug.
I prefer that the hearths of the furnace should be made rather deeper than is
ordinarily the case.
The twyer should dip into the metal so that the twyer holes are at least three (3)
inches below the surface of the metal.
The twyer is inserted and the blast turned on directly the charge is completely
melted, and the blowing continued for from half an hour to an hour, till a sample
taken from the furnace shows that nearly all or all the carbon is removed; the twyer
is then withdrawn, and the charge finished in the ordinary way.
If a phosphoric pig is being treated on a basic hearth, additions of ore and lime
should have been made before the twyer was introduced.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Sidney Gilchrist Thomas in the Great Seal Patent Office on the
16th September 1879.
SIDNEY GILCHRIST THOMAS, of 3, Queen's Road Villas, Queen's Road, Battersea,
in the County of Surrey. "IMPROVEMENTS IN THE MANUFACTURE OF STEEL."
My Invention relates to a method of accelerating and improving the Siemens,
Siemens-Martin, Siemens-Pernot, or similar open-hearth steel processes, so that
phosphoric iron may be successfully treated for the production of steel or ingot-iron
almost entirely free from phosphorus, by introducing blast into the bath of metal
through removable twyers, which are introduced or withdrawn at will through the
top or sides of the regenerative gas-furnace, in which the process is conducted. In
carrying out this Invention I use the Siemens or other regenerative gas-furnace,
first providing it with a calcareous or magnesian hearth (such as I have described
in my Patents, No. 908, in the year 1878, and Nos. 131 and 257, in the year 1879).
I introduce the twyer through an opening made for the purpose on either side of
the furnace, always above the level of the metal in the hearth. The twyer aperture
may also be in the roof of the furnace, but it is preferably situated in the side. In
either case it should be so placed that the twyer may enter the bath near its deepest
part. The twyer may conveniently consist of a wrought-iron pipe, of some six
inches in diameter, protected by a very thick casing or external pipe of a highly
refractory basic material, preferably magnesian lime, which has been burnt at a
white heat, mixed with tar, or limestone and silicate of soda may be used. The
iron pipe is not continued quite to the end of the twyer. The end of the twyer is
perforated with several holes, through which the blast is delivered in a downward
direction some inches below the surface of the metal.
.
The introduction of the twyer and its withdrawal from the furnace may be
effected either by a rack and pinion and a telescopic joint,.or in any other convenient
mode. The pressure of blast may be from three pounds upwards. In order to cool
the twyer I sometimes introduce a second wrought-iron pipe of very much smaller
diameter into the large twyer-pipe. This internal pipe is open at both ends. The
one end terminates some inches short of the blast delivery holes. The other end
passes out through a hole in the blast-pipe clear of the furnace. An air-tight
packing must of course be provided at this point. By this arrangement a greater
amount of air is passed through the twyer than can be advantageously introduced
into the metal, the excess passing out through the small pipe, of which the diameter
is so small that the greater part of the blast is forced to pass through the bath of
metal. It is preferable that the hearth should be somewhat deeper than is ordinarily
the case.
Before introducing the charge into the furnace I spread on the hearth a layer of
limestone, and then a layer of limestone mixed with a little oxide of iron. The
object is with this and subsequent additions made during the progress of the opera-
tion to produce a highly calcareous slag, containing at least 40 per cent. of lime, or
lime and magnesia phosphoretic pig-iron, from which nearly all or all the silicon has
, been removed by refining in a Bessemer converter, is very suitable for treatment by
my present Invention. After the charge is well melted down the twyer is intro-
duced, and the metal is blown with, if necessary, occasional additions of limestone
and ore, till the carbon and phosphorus are removed, as indicated by samples. The
twyer is then withdrawn and the slag tapped off. I then prefer to add a little
hematite-pig before finishing the charge with spiegel or ferromanganese in the usual
way. By this process not only is the operation much shortened, but a high-quality
of steel is obtained from cheap phosphoretic iron.
I do not claim the use of blast in a puddling or refining-furnace, but I claim the
improved process herein described for the manufacture of ingot steel or ingot-iron,

page_text: in an openhearth regenerative furnace with a calcareous lining, in combination with
large basic additions, by the introduction of blast through removable twyers,
substantially in the manner described..
In witness wliereof, I, the said Sidney Gilchrist Thomas; have hereunto set
my hand and seal, this Sixteenth day of September, in the year of our 5
Lord 1879..
SIDNEY. G., THOMAS. (L.S.)