IMPROVEMENTS IN REPAIRING AND LINING BESSEMER CONVERTERS AND FURNACES."
Year: 1880

page_text: LETTERS PATENT to Sidney Gilchrist Thomas, of 27, Tedworth Square, Chelsea,
London, Metallurgist, and Percy Carlyle Gilchrist, now of 6, The Esplanade,
Redcar, Yorkshire, Metallurgist, for an Invention of “IMPROVEMENTS IN
REPAIRING AND LINING BESSEMER CONVERTERS AND FURNACES."
PROVISIONAL SPECIFICATION left by the said Sidney Gilchrist Thomas
& Percy Carlyle Gilchrist at the Office of the Commissioners of Patents on
the 21st October 1880.
SIDNEY GILCHRIST THOMAS, of 27, Tadworth Square, Chelsea, London,
Metallurgist, and PERCY CARLYLE GILCHRIST, now of 6, The Esplanade, Redcar,
Yorkshire, Metallurgist. "IMPROVEMENTS IN REPAIRing and LINING BESSEMER
CONVERTERS AND FURNACES."
By our Invention the repairing or lining of Bessemer converters or converter
bottoms or other furnaces with basic materials is effected much more rapidly and
cheaply than is ordinarily the case. We take a mixture of hard shrunk lime
(though sometimes other lime may be used) and tar mixed in such proportion as
to make when hot a liquid mass, a good proportion consisting of from 3 to 5 parts
lime to one of tar. For repairing or lining Bessemer converters this is used as
follows: The converter of which the lining is to be repaired is placed vertically,
preferably neck downwards, and the bottom taken off. An iron mould in from 3
to $ pieces, one or more of which should be wedge shaped, so arranged that when
put together the exterior of the inould has the shape which it is desired to give the
interior surface of the converter lining, is lowered into the vessel and fastened
by wedges into the proper position; this mould is provided with interior cross bars
fitting into sockets in the inside of the sectional pieces by which they are held
together or some such equivalent device (such as external wrought iron bands), so
that when the cross bars are knocked out and the wedge pieces loosened, the several
sections of the mould collapse, and the mould can be readily withdrawn from the
converter in pieces. A very thin sheet iron casing may be used to cover the
exterior of the mould or pattern. Across the neck of the vessel five bars are laid
and a large fire built up inside so as thoroughly to heat the mould; the interior of
ΓΕ

page_text: soon
the converter itself should have been previously heated to a red heat. When
repairing a vessel for which this Invention is specially applicable, the heat of the
previous operations is utilized by inserting the lining mould in the hot vessel as
as possible after the last operation; the hot liquid lime and tar mixture
previously described is slowly poured or thrown between the mould and the vessel
shell, so as to completely fill the space; the fire is kept up till the liquid lime mass
sets hard. The pattern or mould is then taken to pieces and withdrawn, and the
vessel after heating is ready for another charge. Converter bottoms and tuyeres
may be similarly manufactured.
Converter bottoms may be made without ramming, the liquid lime being thrown
into the hot mould round tho tuyeres or tuyere moulds, and the whole being then
coked in an oven. Tuyeres may also be manufactured in a similar way, as may
also furnace hearths. The shrunk lime we use for making the liquid lime we find
we can economically manufacture by burning magnesian limestone or lime in a
cupola lined with lime and tar or lime bricks. Ordinary lime may also be used for
burning in the cupola if dolomite or magnesian lime cannot be obtained, but it
should contain silica and alumina in larger quantity than is necessary with
dolomite lime. The heat in the cupola must be raised to an intense white so as
to thoroughly shrink the lime exposed to it; if this point is not attended to the
operation will not be successful.
The cupola should have a drop bottom, and preferably be of larger section at the
bottom than at the top. It should also have preferably double rows of tuyeres,
and is best supplied with hot blast. The fuel used is coke, or a mixture of coke
and coal, or a gas cupola may be used for the purpose.

page_text: PECIFICATION in pursuance of the conditions of the Lettors Patent filed by
the said Sidney Gilchrist Thomas & Percy Carysle Gilchrist in the Great
Seal Patent Office on the 5th April 1881.
SIDNEY GILCHRIST THOMAS, of 27, Tedworth Square, Chelsea, London,
Metallurgist, and Percy Carlisle Gilchrist, now of 6, The Esplanade, Redcar,
Yorkshire, Metallurgist. "IMPROVEMENTS IN REPAIRING AND LINING BESSEMER
CONVERTERS AND FURNACES.”
For
By our Invention the repairing and lining of Bessemer converters and converter
bottoms and other metallurgical furnaces with calcareous or magnesian basic
materials is effected much more rapidly and cheaply than is ordinarily the case, it
being now necessary to defer repairs or relining till the vessel or furnace is cold
(which is a cause of great loss of time), and to use much expensive labour in
inserting the repairing material. Our Invention also relates to a highly economical
and efficient method of producing basic lining material. We prepare a mixture of
hard shrunk magnesian lime (though sometimes when this is not to be obtained
other limo may be used) and of tar mixed in such proportion as to make when
hot a liquid mass, a good proportion consisting of from one and three quarter (14)
to four (4) parts by volume of lime, to one (1) of tar; the harder shrunk the line
is the less tar is necessary. For good shrunk lime we prefer three (3) parts of lime
to one (1) of boiled tar. The lime is coarsely ground and mixed with the tar in a
mortar mill or pug mill which may be advantageously steam jacketed.
repairing or lining Bessemer converters this mixture is applied as follows:-The
converter of which the lining is to be repaired is placed vertically, either throat
upwards or bottom upwards. If the vessel is placed throat upwards the throat
section is removed; if it is preferred to repair the vessel bottom upwards, the
bottom section is removed to admit of the insertion of the pattern. It is of course
necessary to have a vessel with easily removeable horizontal joints; what is
known as the symmetrical type of vessel is the most convenient. A mould which may
be either of cast or wrought iron or steel in from two (2) to eight (8) picces, one or
more of which should be wedge shaped (so arranged that when put together the
exterior of the mould has the shape which it is desired to give the interior surface
of the converter lining), is lowered by a crane or otherwise into the vessel aud
fastened into the proper position; this mould is provided with interior cross bars
fitting into sockets in the inside of the sectional pieces by which they are held
together or some similar device, so that when the cross bars are knocked out and
the wedge pieces loosened, the several sections of the mould collapse, and the
mould can be readily withdrawn from the converter in pieces. When the converter
is a large one the mould may be in two rings or horizontal sections, each
about 4 feet high, the two parts being inserted separately, but this is not generally
desirable.
A mould in one piece may always be used if the taper of the lining is considerable;
a very thin sheet iron casing may sometimes be used to cover the exterior of the
mould or pattern. A sheet iron mould made of plates about five eights (*) of au inch
thick may be used very conveniently, being much lighter than a cast iron mould.
The lower parts of the interior of the mould should be protected with thin bricks
or fire clay. When repairing throat upwards, a fire is built up ou the bottom of
the converter inside the mould and a little blast is applied so as to thoroughly heat
the mould. We prefer that the converter shell or partly worn lining itself should
preferably also be quite hot, which will be the case if the repairs are commenced
soon after the termination of a blow. The slag resulting from previous operations
should however be first removed from the lining with long bars. If it be preferred

page_text: to repair throat downwards, we place across the neck of the vessel temporary fire-
bars, and a temporary blast box and blast connection, to be used as before described.
The liquid lime and tar mixture previously described (which we prefer to previously
heat by keeping it in an iron bosh or cauldron with a steam jacket or with steam
pipes passing through it, or by keeping it in an iron bosh or cauldron in a stove, which
should be warm enough to keep the mixture in a liquid state, but not hot enough
to fire the tar. The stove may be conveniently heated by steam or hot water
passing through pipes along its sides, care being taken in all cases not to allow
any steam to escape into the lime tar), is poured or thrown between the mould and
the vessel shell, so as to completely fill the intervening space. The fire is kept up
till the liquid lime mass sets hard, which will take place in from two to four hours.
We prefer to cover the converter top loosely with a bricked iron lid, so as to direct
the flame against the walls of the moulds. The pattern or mould is then taken to
pieces and withdrawn, and the vessel after heating is ready for another charge of
iron. Converter bottoms and tuyeres may be similarly manfactured. Thus
converter bottoms are made without ramming as follows:-the liquid lime is
thrown into the ordinary circular iron bottom mould (which may be either hot or
cold) round the tuyeres or tuyere pins, and the whole is then coked in an oven or
stove, for from four (4) to nine (9) days, preferably at a low red heat. Before
placing the bottom in the stove, we prefer to place on it a heavy iron plate and
weights. The mixture used for bottoms is less liquid than that used for lining.
Tuyeres may also be manufactured in a similar way. Changeable sections of
converters may be similarly lined or repaired, without necessarily being dried in a
stove. Furnace hearths and cupola linings may be made or repaired in an exactly
similar manner, but the system is especially useful for repairing. The shrunk lime
we use for making the liquid lime herein described, as well as for basic furnace
linings and bottoms, we find can be very economically and well manufactured by
burning magnesian limestone or magnesian lime in a 'cupola lined with a basic
material, preferably with either a rammed lining of lime and tar, or with lime
bricks, or a lining made as herein before described. Ordinary lime or limestone
may be also used for burning in the cupola, if dolomite or magnesian lime cannot
bo obtained, but it should contain silica and alumina in larger quantity than is
necessary with dolomitic lime. About 4 to 5 per cent. of silica and alumina
together are desirable. In preparing the hard lime in the cupola, the following is
a convenient mode of operating :—We first charge coke alone for five (5) or ten (10)
feet above the tuyeres.
We then charge about equal volumes of coke and dolomite, the latter being
preferably broken to about the size of a fist. Plenty of blast is admitted, being
preferably distributed through numerous tuyeres. The tuyeres are best placed
within a few inches from the bottom, and we greatly prefer to use hot blast at a
pressure of at least one or two pounds on the inch, though a less pressure may be
used. Plenty of blast and large tuyere area are indispensable. Charging is continued
sometimes with a reduction of the proportion of coke used till the lower part of
the cupola is completely full of shrunk dolomite and the charges descend very
slowly. This will generally occur after 5 or 6 hours. After all the coke is burnt
out, the bottom of the cupola (which we prefer to be a flat circular wrought iron
plate, covered with three or four inches of lime and tar, and fastened to the shell
of the cupola with bolts and cotters) is then removed and run on one side; this
may be conveniently done by allowing it when unfastened to slide on one side on
two rails, which are placed a few inches below the bottom of the cupola.
The cupola itself is conveniently supported on iron pillars, so as to allow of a
truck being run underneath it to receive the burnt material. When the bottom
has been removed, the shrunk lime which will be in part sintered together is
loosened by bars from below, and a "monkey" used from the charging door and
discharged into the wagon. The bottom is then put on again and the operation
repeated. The heat in the cupola must be always maintained for some time at an
intense white heat, so as to thoroughly shrink the lime, or the operation will not be

page_text: successful. We prefer the cupola to be of larger section below than above, thus we
have found a diameter of five or six feet at the charging door, and seven or eight
at the bottom, answer well with a height of 15 feet between the charging door
and tuyeres. Instead of a coke, or coke and coal cupola, a gas cupola may be
sometimes used with advantage particularly where coke is dear. In this case we
prefer to have one ordinary gas generator, supplying three or more cupolas, ench
about 16 or 20 feet high and or 8 feet in diameter, and we burn the gas with
pressure blast. It is very advantageous to either heat the blast by passing it
through brick regenerators heated by the waste heat of the cupolas, or by causing
it to traverse another cupola in which a charge of dolomite has been previously
burnt and has not had time to cool. In this case also the cupola must have a basic
lining. In any case the temperature must be maintained at an intense white heat
to give good results.
Having thus described our Invention, we claim,—
First. The herein before described improvements in the method of repairing and
making basic linings for Bessemer converters and other metallurgical furnaces, by
by means of a liquid or semi-liquid mixture of lime and tar without ramming,
substantially as set forth.
Second. The herein before described method of manufacturing hard shrunk lime
for lining Bessemer converters and other metallurgical furnaces, by burning
dolomite or limestone in a basic lined cupola at an intense white heat, substantially
as set forth,
In witness whereof, I, the said Percy Carlyle Gilchrist, have on my own
behalf, and on behalf of the said Sidney Gilchrist Thomas, hereunto
set my hand seal, this First day of April, in the year of our Lord 1881.
Witness,
WM. L. SKINNER,
PERCY C. GILCHRIST. (L.S.)