IMPROVEMENTS IN THE MANUFACTURE OF STEEL
Year: 1879

page_text: LETTERS PATENT to Sidney Gilchrist Thomas, of 3, Queen's Road Villas,
Wandsworth Road, London, for the Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF STEEL."
Sealed the 14th October 1879, and dated the 30th April 1879.
PROVISIONAL SPECIFICATION left by the said Sidney Gilchrist Thomas at
the Office of the Commissioners of Patents on the 30th April 1879.
SIDNEY GILCHRIST THOMAS, of 3, Queen's Road Villas, Wandsworth Road,
London. "IMPROVEMENTS IN THE MANUFACTURE OF STEEL."
My improvements relate to the manufacture of steel in Bessemer converters and
open hearth furnaces, but more especially in the Bessemer process, when using basic
calcareous linings from phosphoretic pig-iron. In carrying out my previous
Invention described in the Specification of my Patents Nos. 289 in the year 1878,
and 1313 in the year 1879, in order to render the highly calcareous basic slag
which I produce, and in which I remove phosphorus readily liquid, I now introduce
with the bases certain readily fusible lime salts, namely, fluor spar or chloride of
calcium, either together or separately.
It is not generally necessary to add of these salts more than one fourth of the
weight of the lime added as described in my previous Specifications. By the use
of these salts a highly liquid slag is produced, which greatly facilitates the removal
of phosphorus. The use of chloride of calcium is particularly advantageous, and
this salt is very cheap. Instead of mixing these salts with the bases they may in
the Bessemer process be injected with the blast.
I also find it often advantageous to blow into the metal with the blast oxide of
iron, but this should not be done till a certain amount of silicon is oxidised, say,
after the first five minutes blow. It is only useful when my calcareous slags and
linings are used. The introduction of the oxide of iron (which may well be what
is known as purple ore) may be readily effected by introducing it through a double
box-hopper into the blast-pipe.
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
29th October 1879.
SIDNEY GILCHRIST THOMAS, of 3, Queen's Road Villas, Wandsworth Road,
London."IMPROVEMENTS IN THE MANUFACTURE OF STEEL"
My Invention relates to the manufacture of steel from phosphoretic pig-iron in
Bessemer converters lined with basic (calcareous or magnesian) materials. In order
to render the highly calcareous basic slag which I produce, as described in my
Patents No. 289 in the year 1878, and No. 1313 in the year 1879, by the addition
of large quantities of lime and in which I remove phosphorus readily liquid, and
[Price

page_text: generally to facilitate the removal of the phosphorus I have found it advantageous
to introduce with the lime certain readily fusible lime salts, namely, fluor spar or
chloride of calcium, either alone or mixed together. It is not necessary to use of
these substances more than one fourth or one fifth of the weight of the lime
addition used as a maximum, a much smaller proportion being generally enough.
Thus, I do not generally find it necessary with ordinary phosphoretic pig to use
more than thirty or forty lbs. of fluor spar or chloride of calcium in addition to
three or four cwts. of lime for every ton of pig treated. The use of a large quantity
of lime is absolutely essential to success. When using chloride of calcium great
care should be taken to keep it absolutely dry, and it should preferably be used
hot. In carrying out my process instead of mixing these salts with the lime which
I throw into the converter, I generally prefer to inject them in fine powder with
the blast. They may with advantage be mixed with two or three times their
weight of powdered lime before being introduced into the blast pipe, the remainder
of the lime being as usual in carrying out my process, as described in my before
referred to Specifications, thrown into the converter in small lumps. If this be not
done the fluor spar or calcium chloride should be mixed in small pieces with the
lime that is thrown into the converter. By the use of these bodies a highly fusible
and liquid calcareous slag is produced, and the removal of phosphorus is greatly
facilitated.
The second part of my Invention consists in facilitating the removal of phosphorus
*by blowing oxide of iron into the phosphoretic pig-iron which is being treated in a
Bessemer converter, with a calcareous or magnesian lining in combination with the
use of large additions of lime so as to produce a highly calcareous slag, the oxide
being introduced into the metal only after a certain amount of silicon has been
oxidised, and the temperature of the metal has been raised to a great
degree; this will be four or five minutes after the commencement of the
blow unless previously blown, and therefore very hot refined metal is used,
when it may be blown in at once.
The oxide of iron may with advantage be
-mixed with an equal weight of powdered lime. I find that one cwt. of oxide for
every ton of metal in the converter is the maximum amount which can be advan-
tageously blown in, even when the silicon and phosphorus are very high, about half
this amount is generally enough. I do not continue to blow in the oxide after the
flame has dropped. Before blowing in the oxide it is often of advantage that a
certain amount of lime should have been blown into the charge. What is known
The oxide may
as purple ore or "blue billy" is a convenient form of oxide to use.
be readily introduced into the blast pipe and so into the twyers through a double
closed hopper, this being a well known mode of introducing reagents into the
Bessemer bath, to which I lay no claim.
I do not claim the mere addition of fluor spar, chloride of calcium, or oxide of
iron in the ordinary Bessemer process.
I have found the use of these substances
in the ordinary Bessemer process useless and often very injurious..
Nor do I claim treating crude iron with mixtures of fluor spar and oxide of iron
in order to produce steel or iron.
But I claim the use of these bodies in dephosphorising steel in the Bessemer
process in combination with the use of calcareous or magnesian linings and large
additions of lime, substantially as and for the purposes herein described.
In witness whereof, I, the said Sidney Gilchrist Thomas, have hereunto set
my hand seal, this Twenty seventh day of October, in the year of our
Lord One thousand eight hundred and seventy nine.