Improvements in Blast Furnace Linings.
Year: 1891

page_text: Date of Application, 14th Aug., 1891
Complete Specification Left, 28th Dec., 1891-Accepted, 30th Jan., 1892
PROVISIONAL SPECIFICATION.
[Communicated from abroad by JAMES GAYLY, of Braddock, in the County of
Allegheny, State of Pennsylvania, United States of America, Metallurgical
Engineer.]
Improvements in Blast Furnace Linings.
I JOHN THOMSON KING of 4 Clayton Square Liverpool in the County of
Lancaster Patent Agent do hereby declare the nature of this invention to be as
follows:-
:-
In constructing a blast furnace, the enclosing walls have heretofore been made
of a refractory quality of firebrick. In the lower portion, commonly known as the
hearth and bosh, it is of great importance that the brick work should be maintained
as nearly as possible to its original thickness, for as the wear increases there is
increased irregularity in the conduct of the process, which entails greater expense,
but in this portion the wear is very rapid, by reason of the chemical action of the
molten cinder, which under the intense heat, has a corrosive and destructive action
on the brick work. The wear at the bosh is found to be especially injurious in the
furnace. As the brick work becomes corroded, there is substituted however,
through the nature of the reactions of the blast furnace process, a more refractory
material, composed largely of carbon, which, to some extent, arrests this destructive
action. It is to this carbon coating that the endurance of the hearth and bosh
walls is due. Walls have been repaired that were originally thirty six inches
thick, where but six inches of the original brick work remained, but were protected
by such carbon coating of a thickness of eighteen inches.
When the furnace lining is new, and before the carbon coating can have had time
to form, the deterioration of the walls at the bosh is very rapid, and during the
work of the furnace the character of the charge is apt to vary at times, and to
produce a corrosive cinder of such chemical nature as will eat away the natural
carbon coating and will attack the brick walls.
It would therefore appear that the furnace would be much better preserved if
the natural process of carbon deposit could be assisted and supplemented by con-
structing the walls of the bosh of a strong and durable material containing carbon
in suitable form. The difficulty of accomplishing this is to secure graphitic material
sufficiently strong to resist the weight of the furnace walls and the scoring action
of the stock as it descends in the furnace.
The above difficulties are overcome by my invention, which consists in con-
structing the walls of the bosh of brick, compounded of refractory fire clay and
graphitic carbon, such as the substance known in commerce as plumbago, blacklead
and graphite. The fire clay forms a bond for the carbon, giving the bricks the
necessary strength and durability to resist compression and abrasion, while making
it in the form of bricks or blocks enables it to be built in a strong and substantial
manner in the furnace walls.
Dad thin Thintooth L.
Ր A
1001
Per pro J. T. KING,
J. Johnson.

page_text: COMPLETE SPECIFICATION.
Improvements in Blast Furnace Linings.
I JOHN THOMSON KING of 4 Clayton Square, Liverpool, in the County of
Lancaster Patent Agent do hereby declare the nature of this invention and in,
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
In constructing a blast furnace, the enclosing walls have heretofore been made
of a refractory quality of fire brick. In the lower portion commonly known as the
hearth and bosh, it is of great importance that the brickwork should be maintained
as nearly as possible to its original thickness, for as the wear increases there is
increased irregularity in the conduct of the process, which entails greater expense
but in this portion the wear is very rapid, by reason of the chemical action of the
molten cinder, which under the intense heat, has a corrosive and destructive action
on the brickwork. The wear at the bosh is found to be especially injurious in the
furnace. As the brickwork becomes corroded, there is substituted however,-
through the nature of the reactions of the blast furnace process, a more refractory
material composed largely of carbon, which to some extent arrests this destructive
action. It is to this carbon coating that the endurance of the hearth and bosh
walls is due. Walls have been repaired that were originally thirty six inches thick,
where but six inches of the original brickwork remained, which were protected by
such carbon coating of a thickness of eighteen inches.
When the furnace lining is new, and before the carbon coating can have had
time to form, the deterioration of the walls at the bosh is very rapid, and during
the work of the furnace the character of the charge is apt to vary at times, and to
produce a corrosive cinder of such chemical nature as will eat away the natural
carbon coating and will attack the brick walls. It would therefore appear that the
furnace would be much better preserved if the natural process of carbon deposit
could be assisted and supplemented by constructing the walls of the bosh of a
strong and durable material containing carbon in suitable form. The difficulty
of accomplishing this is to secure graphitic material sufficiently strong to resist the
weight of the furnace walls and the scoring action of the stock as it descends in the
furnace.
The above difficulties are overcome by my invention, which consists in con-
structing the walls of the bosh of brick, compounded of refractory fire clay and
graphitic carbon, such as the substance known in commerce as plumbago, blacklead,
and graphite. The fireclay forms a bond for the carbon, giving the bricks the
necessary strength and durability to resist compression and abrasion, while making
it in the form of bricks or blocks enables it to be built in a strong and substantial
manner in the furnace walls.
To make the bricks I prefer to proceed as follows:-In an ordinary pug-mill or
dry pan
I mix fire-clay and the graphitic carbon above mentioned in proportions
which may be from twenty-five to fifty per centum of graphitic carbon, and from
fifty to seventy-five per centum of fire-clay. The most desirable proportions I have
found to be about twenty-five per centum of graphitic carbon and seventy-five per
centum of fire clay, though my invention is not limited to any special proportions
of the parts, which may be varied, according to the judgment of the skilled
furnace engineer.
This compound I temper and mould into the form of bricks, suitable for building
in furnace walls, and burn them in the usual manner in the manufacture of fire-
brick and in this operation it will be found that no sensible deterioration is caused
by combustion of the carbon. I then build these bricks in the inwalls of the bosh
of the furnace for example so that they shall constitute eighteen inches, more or
less, of the thickness of the walls, and in setting them I may use as a mortar a
mixture of fireclay and carbon compounded substantially in the manner and in

page_text: proportions as above stated. The strength of the bricks is such that they do not
weaken the structure of the furnace, and in their practical use I have found them
of great benefit in preserving the walls and consequently in making the work of the
furnace uniform and economical. When the furnace is first started into blast,
instead of presenting bare bosh-walls liable to be corroded by the cinder, the carbon
bricks resist this action of the cinder, and are themselves renewed and supplemented
by the natural deposit of carbon in the furnace. The saving which 1 thus secure
is very considerable and will be appreciated by those who practise my invention.
In making brick for the boshes, I may substitute for the graphitic carbon, other
forms of carbon, such as pulverized anthracite coal, charcoal or coke, though bricks
thus made are not so strong or durable.
As an additional improvement, I may add to the compound of which the bricks
are made, some lime or other basic material, such as magnesia, which may amount
to about twenty per centum, or less of the whole mass if lime be used, and five per
centum or less if magnesia be used. This will render the bricks still more refractory
and durable, but my invention broadly considered, covers the bricks whether con-
taining the basic material or not.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, 1 declare that what I
claim is :-
:―
First. A blast-furnace having in the walls of its bosh, bricks containing
refractory clay and carbon; substantially as and for the purposes described.
Second. A blast furnace having in the in-walls of its bosh bricks containing
refractory clay and graphitic carbon; substantially as and for the purposes
described.
Third. A blast-furnace having in the inwalls of its. bosh, bricks containing
refractory clay and carbon, set in mortar of similar composition; substantially as
and for the purposes described.
aith dow of December 1891.
Per pro J.T. KING,
J. Johnson,
Agent.