IMPROVEMENTS IN THE MANUFACTURE OF IRON AND STEEL, AND THE APPARATUS USED THEREIN.
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by Sidney Gilchrist Thomas at the Office
of the Commissioners of Patents on the 28th January 1880.
SIDNEY GILCHRIST THOMAS, of 3, Queen's Road Villas, Wandsworth Road,
London. "IMPROVEMENTS IN THE MANUFACTURE OF IRON AND STEEL, AND THE
APPARATUS USED THEREIN.'
"
My Invention relates to various improvements in my already patented processes
for the manufacture of steel and basic furnace linings, as described in my Patents
No. 908, in the year 1878; No. 289, in the year 1878; No. 1313, in the year 1879;
I find
and No. 1711, in the year 1879. My present improvements are as follows.
in the manufacture of high class steel and ingot iron it is advantageous to conduct
the process as follows:-I first blow the metal, which I prefer to be a special pig
low in silicon, and high in manganese and phosphorous, in a Bessemer converter,
fixed or tipping, with a basic, preferably magnesian lime, lining and basic additions
till great part or all of the silicon and the carbon is removed; I then rapidly
transport it into a basic lined open hearth furnace, also with a basic lining and
basic additions, where I finish the operation, and may, if necessary, add the spiegel.
I sometimes also melt the pig with limestone, and preferably oxide of iron, in a
lime lined cupola and then treat it in a lime lined Bessemer converter with lime
additions. I find, when carrying out my basic Bessemer process, that the presence
of manganese is of such importance that when treating pig poor in manganese,
spiegel should be added to the pig in the cupola, or, as I generally prefer it, added
to the metal in the converter after the carbon flame appears or before the drop of
the flame. This is particularly advantageous when the silicon in the pig is high; by
this means the waste is diminished and the quality improved. In the ordinary
Bessemer practise the bottom or plug of the converter is not more than about
twenty inches thick, but it is useful when carrying out my basic Bessemer process
to make it from 28 to 35 inches thick so that it is not necessary to frequently
renew the bottom as is now done. When blowing powdered lime into the basic
converter I make the bottom plates of the blast box sloping so that the blast box
has a triangular section, or I put in a sloping false bottom; in this way the lime
powder is more easily directed into the holes and prevented from lodging in the
box. Basic linings for furnaces may be formed by mixing lime or limestone,
preferably magnesian limestone, with sulphate of lime or sulphate of magnesia,
using the mixture as a rammed lining or making it into bricks and firing at a high
heat. In making basic linings phosphate of lime is a useful body to mix with

page_text: I have
limestone or lime, especially for twyers, to prevent too much shrinkage.
also used as a basic brick material a mixture of about 100 parts of limestone with
about 60 parts of salt, exposing the bricks made of this mixture to a high heat, in
the same way a rammed lining may be formed.
I also sometimes line the upper part of the converter with bricks of plumbago
or coke dust mixed with fire clay pressed into bricks under great pressure. The
vessel should have a wide mouth and a removeable central conical stopper which
prevents the loss of heat and the accumulation of slag. It may be advantageously
combined with a removeable central air twyer for burning the gases. In localities
where converters are near blast furnaces producing basic or very manganiferous 1
slags with less than thirty per cent. of silica it is often economical to use these slags,
particularly if they can be run in in a liquid state mixed with lime for the
basic addition in my basic Bessemer process.