Improvements in Blast Furnace Linings.
Year: 1891

page_text: Date of Application, 9th Nov., 1891
Complete Specification Left, 28th Dec., 1891-Accepted, 30th Jan., 1892
PROVISIONAL SPECIFICATION.
[Communicated from abroad by JAMES GAYLEY, of Braddock, in the County of
Allegheny, United States of America, Metallurgical Engineer.]
Improvements in Blast Furnace Linings.
I JAMES JOHNSON 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
commonly of a refractory quality of firebrick. In the lower portion commonly
known as the hearth and bosh it is of great importance that the brickwork should
be maintained as near 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. As such corrosion proceeds there is substituted however,
through the reactions of the blast furnace process, a more refractory material
composed largely of carbon, which to some extent, arrests the 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 36 inches thick, where but six
inches of the original brickwork remained, which was protected by a coating of this
carbon material for a thickness of 18 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 and hearth 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 walls would be much better preserved
if the natural process of carbon deposit could be assisted and supplemented by
constructing the walls of the hearth and crucible, and bosh, of material composed
largely of carbon. The difficulty consists in securing the carbon in the form of a
brick or tile that will be sufficiently strong to maintain the rigidity of the wall. I
have overcome this by making a brick of coke or its equivalent, and tar which acts as
the binding material for the brick. The tar, through heating, has the volatile
matter driven off, and leaves behind a hard and durable residue that cements the
particles of coke into a firm mass.
An alternative lining suitable for the walls of the bosh consists of bricks compounded
of refractory fireclay and graphitic carbon such as the substances known in commerce
as plumbago, black lead, 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 the compound in the form of bricks or blocks enables it to
be built in a strong and substantial manner in the furnace walls.
Dated the 7th day of November 1891.