AN IMPROVED LINING FOR CUPOLA FURNACES, ALSO APPLICABLE TO THE FORMATION
Year: 1872

page_text: LETTERS PATENT to George James Snelus, of Dowlais, in the County
:
of Glamorgan, Metallurgical Chemist, for the Invention of "AN
IMPROVED LINING FOR CUPOLA FURNACES, ALSO APPLICABLE TO THE FORMATION
39.
Sealed the 20th September 1872, and dated the 25th March 1872.
PROVISIONAL SPECIFICATION left by the said George James Snelus
at the Office of the Commissioners of Patents, with his Petition,
on the 25th March 1872.
I, GEORGE JAMES SNELUS, of Dowlais, in the County of Glamorgan,
Metallurgical Chemist, do hereby declare the nature of the said In-
vention for "AN IMPROVED LINING FOR CUPOLA FURNACES, ALSO APPLICABLE
TO THE FORMATION OF THE BEDS OF REVERBERATORY FURNACES," to be as
follows:
Hitherto fire-clay, silica, ganister, and like materials have been used
as fire-resisting substances for lining cupola furnaces, and for the beds
of reverberatory furnaces. Now all these substances are either essentially
silica or contain a large proportion of the same. As all chemists are
aware silica plays the part of an acid in combining with bases at high
temperatures. But when metals are melted they become more or less

page_text: oxidized, and the oxide so formed tends to combine with the siliceous
lining of the furnace, and to wear the latter away by forming with it a
fusible body. This difficulty is generally sought to be overcome by
putting limestone with the charge in cupola furnaces. But I make the
lining of cupola furnaces and the beds of reverberatory furnaces entirely
of some basic body, by preference lime or magnesia, or mixtures of
these substances, with or without a small quantity of oxide of iron to
cement them and to form a slight glaze on the surface.
The lime or magnesia or mixture of these well burnt, and with or
without oxide of iron, is rapidly crushed and kept hot enough during use
to prevent the absorption of moisture. It is then rammed in between
the cupola casing and the core in the usual way, and after being fired
forms not only the most refractory and fire-resisting material that can
be used, but also on account of its aforesaid basic nature has no tendency
to be worn away by the chemical action of the oxide formed. A little
limestone is as usual added to the charge in cupola furnaces to form a
neutral slag with the ash of the fuel. This may also be added in
reverberatory furnaces. In the latter special precautions are required to
prevent the basic lining coming in contact with bricks or the like, and
for this purpose I mix a little well-burnt coke dust with lime to form a
layer next to the basic lining, and gradually increase the quantity of
coke dust and decrease the lime or other like material until there is
nothing but a layer of coke dust in contact with the bricks.
In special cases I also use this mixture of coke dust and lime or other
like material to form the refractory lining itself.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said George James Snelus in the Great Seal Patent
Office on the 24th September 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
JAMES SNELUS, of Dowlais, in the County of Glamorgan, Metallurgical 3
Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fifth day of March, in the year
of our Lord One thousand eight hundred and seventy-two, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors, 3

page_text: give and grant unto me, the said George James Snelus, Her special
licence that I, the said George James Snelus, my executors, admi-
nistrators, and assigns, or such others as I, the said George James
Snelus, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"AN IMPROVED LINING FOR CUPOLA FURNACES, ALSO APPLICABLE TO THE FORMATION
OF THE BEDS OF REVERBERATORY FURNACES," upon the condition (amongst
others) that I, the said George James Snelus, my executors or adminis-
trators, by an instrument in writing under my, or their, or one of their
hands and seals, should particularly describe and ascertain the nature of
the said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said George James Snelus, do hereby
declare the nature of my said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement :—
My Invention relates to an improved material for lining cupola and
other furnaces, and for the beds of reverberatory furnaces.
Hitherto fire-clay, silica, ganister, and similar materials have been
used as fire-resisting substances for lining furnaces in which metals are
melted. Now all these substances are either essentially silica or contain
a large proportion of that body. As all chemists are aware silica plays
the part of an acid in combining with bases at high temperatures. But
when metals are melted or "blown," as in the "Bessemer" process,
they become more or less oxidized, and the oxides so formed combine
with the siliceous lining of the furnace, and wear it away by forming with
it a fusible slag.
When iron is melted in a cupola furnace limestone is added to the
charge to remove the sulphur and flux the ash of the fuel, and this
further adds to the difficulty.
I make the lining of all furnaces in which metals or oxides are melted
or operated upon while fluid entirely of some basic body, by preference
lime or magnesia, or mixtures of these substances, with or without a

page_text: small quantity of oxide of iron to cement them and to form a glaze
upon the surface. In special cases I make a mixture of finely ground
coke dust and lime for the refractory lining.
There are several methods of applying these materials.
First. The well-burnt lime or magnesia, or a mixture of these sub-
stances, with or without oxide of iron or coke dust, is rapidly crushed
and kept hot enough to prevent it absorbing moisture. It is then
rammed in between the core and the iron casing of the vessel to be
lined, which may be a cupola, revolving furnace, "Bessemer" convertor,
or iron box to form the bed of a reverberatory furnace. If bricks are used
in the reverberatory furnace, and in other cases where bricks are used,
the above lining should be separated from the brickwork by a mixture
of lime and coke dust, gradually increasing the coke dust and decreasing
the lime as the separating material approaches the brickwork.
Another method of putting in this basic lining is to grind the unburnt
limestone or magnesian limestone, with or without a little oxide of iron
into a stiff paste with a little water, and then to ram the space to be
lined in the cupola revolving furnace, "Bessemer" convertor, rever-
beratory furnace, or other apparatus with this material, which is plastic
like clay. It is then carefully dried and fired. After drying it will be
hard and compact, and when fired at a high temperature will become
glazed on the surface and converted for some depth into lime. In this
case it is necessary to make provision for the escape of the carbonic acid
liberated, as the limestone burns to lime. This can generally be done
by drilling a few holes in the outer casing. I then find no difficulty in 1
keeping the lining in form, either in the cupola or in the "Bessemer "
convertor, as it does not break away. It also lasts longer than the
ordinary materials now used, as it is too refractory to melt itself, and it
is not affected like a siliceous lining by the action of melted oxides. A
portion "slags away," but nothing like so much as when bricks or
ganister are used. Thus I bave found that when iron is melted in an
ordinary cupola lining there will be from sixty to eighty per cent. of silica
in the slag, and the slag from a "Bessemer" convertor lined with ganister
contains generally from fifty to seventy per cent. of silica; while in a
cupola lined as first described the slag obtained by melting a charge of
iron in it contained only thirty-five per cent. of lime, and the slag from
performing the." Bessemer" process in a vessel lined with limestone con-
taired only fifteen per cent. of lime, thus showing how much less the

page_text: basic lining is acted upon than the siliceous lining. There are besides
other advantages accruing from the use of a basic lining in the place
of a siliceous one.
Another method of forming this basic lining is to compress the
ground materials into bricks, and use these either burnt or unburnt; or
the material may be used in the form of quarried blocks, which should
be sound and without veins of foreign material running through them.
Whatever method is used, it is of course desirable that the material
should contain as little silica as possible.
Of the methods above described I prefer that in which the material
when put in is like ground limestone, but other methods of putting
in the material will suggest themselves, and I do not limit myself
to the above methods of using it. When this material is used for lining
Bessemer" convertors it is evident that the ordinary fire-clay tuyeres..
cannot be used, and I adopt the Russian plan of putting in a couple of
large horizontal tuyeres of wrought iron, replacing them as necessary.
66
Having thus fully described my said Invention, and the manner of
performing the same, I wish it understood I am aware that it has been
proposed to use ground limestone for the bottoms of heating furnaces for
iron, and also that limestone blocks have been used for the sides of
puddling furnaces, it has not however been found to answer well; in
the first case, because the heavy masses of iron tear up the bottom
when being dragged about on it; and in the second case, because
particles of lime are liable to get entangled in the puddled ball, and
make a refractory slag not easily squeezed out; and I do not claim the
use of lime or limestone for either of the above purposes; but I claim
an improved furnace lining made and applied substantially in the
manner herein described.
In witness whereof, I, the said George James Snelus, have here-
unto set my hand and seal, this Twenty-first day of September,
in the year of our Lord One thousand eight hundred and seventy-
GEORGE JAMES SNELUS. (L.S.)