IMPROVEMENTS IN THE MANUFACTURE OF REFRACTORY BASIC BRICKS, AND IN REFRACTORY MATERIALS FOR LINING AND CONSTRUCTING FURNACES, CONVERTERS, AND OTHER VESSELS USED IN THE MANUFACTURE OF IRON AND STEEL
Year: 1879

page_text: LETTERS PATENT to Sidney Gilchrist Thomas, of 3, Queen's Road Villas,
Queen's Road, Battersea Park, in the County of Surrey, for the Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF REFRACTORY BASIC BRICKS, AND
IN REFRACTORY MATERIALS FOR LINING AND CONSTRUCTING FURNACES,
CONVERTERS, AND OTHER VESSELS USED IN THE MANUFACTURE OF IRON
AND STEEL,"
Sealed the 8th April 1879, and dated the 11th January 1879.
PROVISIONAL SPECIFICATION left by the said Sidney Gilchrist Thomas at
the Office of the Commissioners of Patents on the 11th January 1879.
SIDNEY GILCHRIST THOMAS, of 3, Queen's Road Villas, Queen's Road, Battersea
Park, in the County of Surrey. "IMPROVEMENTS IN THE MANUFACTURE OF
REFRACTORY BASIC BRICKS, AND IN REFRACTORY MATERIALS FOR LINING AND
CONSTRUCTING FURNACES, CONVERTERS, AND OTHER VESSELS USED IN THE
MANUFACTURE OF IRON AND STEEL."
My improvements relate to the manufacture of basic refractory bricks, and linings
for all furnaces, converters, &ct., used in tho manufacture of steel and iron. By the
use of these basic slags are enabled to be produced, in which phosphorus may be
removed, as described in my Patent No. 289 in the year 1878. To make these bricks,
linings, &ct., I take magnesian limestone of approximately the composition described
in the Specification of my Patent No. 908 in the year 1878, containing at least five
or six per cent. of silica and alumina (or silica, alumina, and oxide of iron); the alumina
or alumina and oxide of iron in the limestone should exceed in amount two fifths of
the silica present. Having fired this limestone at an intense and prolonged white
beat in blocks, lumps, or bricks, so as to cause the formation of the hard compact
shrunk structure characteristic of the basic bricks described in my Patent last
quoted, I crush and mix the resulting lime compound (preferably while fresh from
the kiln) with enough liquid tar to form a somewhat plastic mass. Out of this
mixture I make bricks, twyers, crucibles, &ct., using considerable pressure for the
purpose, and firing them after they are made at an intense and prolonged heat. I
also use this mixture as a rammed lining for furnaces, particularly Bessemer
conventers and open-hearth steel furnaces. Instead of using in the first instance
the highly burnt and shrunk lime I also take a limestone of the kind already
described, and having burnt it at a moderate heat I mix it with tar, as already
'

page_text: described, and mould it under pressure into bricks, twyers, &ct., or use it as a
rammed lining, and then apply the prolonged and intense heat which is necessary
to secure the requisite hard compact structure I have in all cases in view. As in
this case the cbief shrinkage takes place after the bricks are made or the linings in
position I regard this as a less desirable mode of proceeding than that first described.
I also sometimes mix with the highly fired lime first described either unburnt lime-
stone, or a moderately burnt lime of similar composition, mixing them thoroughly
before adding the tar, and afterwards submitting the bricks, &ct., or linings made
of the mixture, to an intense and prolonged heat so as to get the compact hard
structure. The shrinkage in this case is not excessive. I also use the mixture of
highly burnt shrunk line and tar as a cement for the bricks herein described
or other calcareous bricks. Crude crcasote may be sometimes used instead of tar,
when it is readily obtainable, for all purposes.

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
10th July 1879.
SIDNEY GILCHRIST THOMAS, of 3, Queen's Road Villas, Queen's Road, Battersea
Park, in the County of Surrey. "IMPROVEMENTS IN THE MANUFACTURE OF
REFRACTORY BASIC BRICKS, AND IN REFRACTORY MATERIALS FOR LINING AND
CONSTRUCTING FURNACES, CONVERTERS, AND OTHER VESSELS USED IN THE MANU-
FACTURE OF IRON AND STEEL."
My Invention relates to the manufacture of refractory basic bricks, twyers, and
linings for converters and furnaces, &ct., used in the manufacture of iron and steel.
By the use of such linings and bricks basic slags are enabled to be produced, as
before described by me, and phosphorus may be thereby removed, as described in
my Specifications No. 289 in the year 1878, and No. 1313 of the present year.
To make these bricks and linings I take magnesian limestone of nearly the com-
position previously described by me in my Specifications Nos. 908 and 3975 of the
year 1878, containing at least six per cent. of silica and alumina, or silica, alumina,
and oxide of iron. I prefer the stone should contain from 4 to 7 per cent. of silica,
from 3 to 5 per cent. of alumina and oxide of iron, and at least 30 per cent. of car-
bonate of magnesia. The silica should not amount to more than double the alumina
and oxide of iron, nor should it exceed a maximum of eight per cent. I fire this
limestone in kilns, not as ordinary lime is burnt, but at a very intense white heat,
exceeding that used for burning firebricks, in rough blocks, bricks, or lumps of
small thickness. By this means I obtain a material of hard, compact, and highly
shrunk structure (the linear shrinkage in the kiln will be generally 25 per cent.) as
described by me in my last referred to Patents. The material is hereafter referred
to as shrunk lime. I crush this hard lime, and mix it, preferably while still fresh
and even warm from the kiln, and in all cases before it has absorbed moisture, with
liquid tar so as to form a somewhat plastic mass. The exact amount of tar added
is best regulated by the operator, who will see when the requisite plasticity is
obtained. About ten parts by weight of shrunk lime to one of tar is a good pro-
portion for bricks and twyers, though less may be used with advantage when, as I
prefer, the bricks and twyers are moulded under great pressure. The mixture may
be conveniently made in a mortar mill, and the tar may be used warm. After the
bricks or twyers have been moulded they are dried in rows only one high for some
48 hours at a temperature sufficiently high to prevent their subsequent softening
when heated in the kiln. With twyers this drying may be conveniently effected
before the iron casing in which the twyer is moulded is removed. After drying the
bricks or twyers are burnt in a kiln at an intense white heat, considerably exceeding
that used for burning firebricks. The kilns should be lined with silica bricks, have
a large fireplace area and a powerful draft, and good hot coals should be burnt.
This intense temperature is absolutely necessary for a good brick. These bricks
should be kept as dry as possible, and may sometimes be dipped in tar to preserve
them from damp if it is necessary to keep them long in stock. For making bricks
an admixture of unburnt limestone of the composition previously indicated may be
used with the shrunk lime. It is in the form of bricks that the mixture of shrunk-
lime and tar may be most advantageously used. It may be however also used as
the material for ramming open-hearth steel-furnace hearths and Bessemer-converter
bottoms. For this purpose I do not grind the shrunk-lime finer than gannister is
ordinarily ground, and I mix it either with tar alone, or with a mixture of equal
parts of tar and crude naptha or other cheap oil, in about the proportion already
mentioned. I dry converter bottoms in ordinary bottom stoves without taking the
sheet-iron casing off. The drying should last at least 48 hours, and the heat
should be sufficient to thoroughly coke the material, so that no further softening or
liberation of gas takes place when it is further heated. A heat approaching a dull

page_text: red is about sufficient. A Pernot or Ponsard furnace hearth may advantageously
have its bottom made of this material rammed when the sides are of lime bricks, as
may also other open-hearth furnaces. In making a cement for lime bricks, for
which purpose my composition is exceedingly valuable, I prefer to use a mixture of
about 15 parts of tar with 1 or 2 of pitch. These I heat in an iron vessel till all
the pitch is liquefied, and then add, constantly stirring, 80 or 90 parts of the finely
ground shrunk-lime. The cement should be rather moro fluid than mortar. In
setting bricks they are dipped in the hot cement, and the cemented edge is then
sprinkled with some of the dry ground shrunk-lime before being set in its place, or
before another brick is set on it. In this way an excellent joint is made. In
making the joint for converter bottoms considerably less tar is used than in making
bottoms' material. In the manufacture of bricks magnesian lime of the ordinary
kind, but made from limestone of the composition given above, and even the
unburnt magnesian limestone, may be used in admixture with the highly fired
shrunk lime. I prefer however to use at least two thirds of the shrunk lime. I
have however sometimes made bricks entirely from this description of magnesian
lime, viz., that burnt in ordinary lime-kilns, and tar. The firing of the bricks
must however he conducted at even a higher and more prolonged temperature than
that required for the bricks from shrunk lime, and there is a considerable shrinkage
in the kiln, so this is not generally desirable. In all cases the use of the highly-
fired hard shrunk magnesian lime is greatly to be preferred, and the composition
of the limestone used is of great importance. I do not now claim the manufacture
of hard shrunk magnesian lime, the manufacture of which has been previously
described by me, but I claim as my Invention, the manufacture of refractory basic
bricks and lining material, & refractory basic cement from the materials, and sub-
stantially in the mannerherein described.
In witness whereof, I, the said Sidney Gilchrist Thomas, have hereunto set my
hand and seal, this Tenth day of July, in the year of our Lord 1879.