IMPROVEMENTS IN BLAST FURNACES
Year: 1867

page_text: LETTERS PATENT to Carl Holste, Civil Engineer, of 12, Henrietta Street,
Covent Garden, in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN BLAST FURNACES."-A communication from abroad by
Frederick Lürmann, in Oesede near Osnabrück, in the Kingdom of
Prussia
Sealed the 17th December 1867, and dated the 17th September 1867.
PROVISIONAL SPECIFICATION left by the said Carl Holste at the
Office of the Commissioners of Patents, with his Petition, on the
17th September 1867.
I, CARL HOLSTE, Civil Engineer, of 12, Henrietta Street, Covent Garden, in
the County of Middlesex, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN BLAST FURNACES," to be as follows:-
This Invention relates to improvements in the hearth of blast furnaces in
which the scoria or slag is continually discharged; but in such manner as to
remain at the same level within the hearth with little fluctuation. The hearth
is closed on all sides, the tymp, the opening in the front of the furnace, and
the dam are all done away with by my construction. The outlet for the scoria
consists of a block of metal in which is a cylindrical hole with conical widenings
at both ends; this outlet may be either flush with the inner wall of the
furnace or it may project a little, the same is fastened to a plate fixed in the

page_text: wall of the hearth by dovetail or otherwise, but so that it may be easily
removed and replaced. The scoria outlet as well as this plate are provided
with canals through which cold water is circulating. The canals of both the
plate and outlet may either communicate with each other or be separate.
The hole in the wall of the hearth in which the scoria outlet is, is somewhat wider
than the outlet itself, the space between is closed with clay, loam, or other
suitable substances. The outlet for the molten metal, the taphole, is in the wall
of the hearth, and being in the immediate contact with the greatest heat may
be easily kept in order.
SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said Carl Holste in the Great Seal Patent Office on the
17th March 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CARL
HOLSTE, Civil Engineer, of 12, Henrietta Street, Covent Garden, in the County
of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventeenth day of September, in the year of our Lord
One thousand eight hundred and sixty-seven, in the thirty-first year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Carl Holste, Her special licence that I, the said Carl Holste,
my executors, administrators, and assigns, or such others as I, the said Carl
Holste, 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 "IMPROVEMENTS IN BLAST
FURNACES," being a communication from abroad, upon the condition (amongst
others), that I, the said Carl Holste, my executors or administrators, 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 imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Carl Holste, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following

page_text: statement, reference being had to the Drawing hereunto annexed, and to the
letters and figures marked thereon (that is to say):-
i
This Invention relates to improvements in the hearth of blast furnaces in
which the scoria or slag is continually discharged, but in such manner as to
remain at the same level within the hearth with as little fluctuation as
possible. The hearth is completely closed by carrying the walls to the
bottom on all sides, the tymp, the fore part of the hearth, and the dam used
heretofore in blast furnaces are all done away with by this construction.
In the accompanying Drawing Fig. 1 is a longitudinal section through
the hearth of an improved blast furnace. taken in the line 1, 2, of Fig. 2;
Fig. 2 is a horizontal section through the same taken in the line 3, 4, of
Fig. 1; Fig. 3, 4, & 5, show various arrangements of the scoria outlet,
scoria, top and side plates; Fig. 6, view and section of the scoria outlet on
an enlarged scale. The same letters indicate like parts in all the Figures.
The scoria discharges itself through the scoria outlet A, from six to ten
inches below the centres of the twyers. This scoria outlet consists of a
block of metal with a cylindrical hole which has conical widenings at both
ends. The same must either project a little into the hearth or be flush with
the wall of it; if it should stand back a little the parts of the wall above
and below have to be cut away in an angle of at least forty-five degrees (see
Fig. 4), else the scoria outlet would be melted away or the slag would not
flow. A plate B which may be, called the scoria plate is fixed in the wall
of the hearth, into this plate the scoria outlet is fastened in such a manner
as to be easily removed and replaced. A. simple and effective way is the
dovetailing as shown in Fig. 3, 4, & 5. The top part of the scoria outlet
forms a dovetail and is put in the corresponding opening of the scoria plate.
A bar a is put across the scoria outlet in the notches 6 of the wrought iron
bolts c riveted into the scoria plate (the notches may be cast on the plate as
shown in Fig. 5); ultimately the outlet is firmly secured in its place by
wrought iron or steel wedges d, d. Both the scoria outlet as well as the
plate are provided with canals through which water is kept circulating; if
they are made of cast iron the canals are best. formed by wrought-iron tubes
cast in as shown in Fig. 6. The water' may be supplied to each separately,
but it is simpler to let it pass through the scoria plate first and from thence to
the scoria outlet, from which it runs off into the free air. A water tap
regulates, the admission of the water; the connection between the canals of
the scoria plate and those of the scoria outlet. may be made of india-rubber
pipes, or better still of copper pipes with flanges or india-rubber joints. The
hole. in the wall of the hearth for the scoria outlet is a little wider than the

page_text: outlet itself, the space between the two e, e, about two or three inches, is
filled with clay, sand, or other suitable materials. If it should be feared that
the wall at the top of the scoria plate will become too hot, a top platè is to
be fixed there, provided with canals for the circulation of cold water, as
shown in Fig. .3. Similar plates may be applied to the sides (as in Fig. 4)
The top and side plates may be cast together with the scoria plate as shown
in Fig. 5; the tap. hole is in the wall of the hearth, instead of being in the
dam as heretofore, it is close to the greatest heat and may be easily kept
in order.
The working of the furnace with the above described improvements is as
follows: The tapping of the molten metal is done in the same way as
heretofore; the scoria outlet needs not be closed as the scoria ceases to
discharge itself as soon as the metal runs off. After the tapping the scoria
outlet must be closed with a little sand or clay, and the water tap turned on
so as to admit but little. water, this takes about four minutes. The blast is
now put on with full pressure; as soon as the scoria is observed at the
twyers the sand or clay in the scoria outlet must be removed and the scoria
crust in the aperture knocked away with a round bar of iron and a hammer,
which operation is greatly facilitated. by the conical widenings of the hole.
All the time the blast remains on with full pressure. The round bar is driven
as far as the fluid scoria and then drawn back with the hands (or if it should
stick too fast, with a chisel and hammer), when the scoria will follow in a
stream of the diameter of the aperture. The water tap must now be turned
on a little more so that the discharged water is lukewarm; the diameter of
the hole is according to the quantity of the scoria to be discharged; for a
large furnace a diameter of one inch and a quarter is sufficient. If the
furnace should for a time produce a larger or smaller quantity of slag, a
scoria outlet of the required size may easily be set in. If only for a short
time less scoria is produced and the blast finds its way through the scoria
outlet, a round bar should be put in so that little scoria or blast can escape
until sufficient scoria has again accumulated to allow the bar to be removed.
No operation in the hearth is required before the next tapping and the blast
particularly must never be stopped. The interval between two tappings has to
be so regulated that the molten metal does not reach the scoria outlet,
otherwise this would be melted away; it is therefore best to tap after a
certain number of charges. The scoria discharged through the tap hole at
the end of the tapping of the molten metal has occupied in the hearth
the space between the molten metal and the scoria outlet, the quantity of
the same will therefore show if the charges may be increased or not. If

page_text: the working of the furnace should by any accident become very bad it is
found to be sufficient if the clay or sand with which the space e, e, round
the scoria outlet is filled is removed. The scoria which flows off there soon
melts away the crust at the aperture, in a short time the usual discharge
through the scoria outlet will be restored, when the space has to be filled up
again.
Having now set forth the nature of the Invention of improvements in blast
furnaces, as communicated to me from abroad, I wish it to be understood
that under the above in part recited Letters Patent I claim,―
First. The use of a scoria outlet of metal cooled by water as above
described for the purpose of the ordinary discharge of scoria.
Secondly. The manner of fixing the scoria outlet in its place with the aid
of the scoria plate as above described.
In witness whereof, I, the said Carl Holste, have hereunto set my hand
and seal, this Sixteenth day of March, in the year of our Lord One
thousand eight hundred and sixty-eight.