IMPROVE- MENTS IN BLAST FURNACES
Year: 1871

page_text: LETTERS PATENT to James Hunter, of Coltness Iron Works, in the
County of Lanark, North Britain, for the Invention of "IMPROVE-
MENTS IN BLAST FURNACES."
Sealed the 20th October 1871, and dated the 24th April 1871.
PROVISIONAL SPECIFICATION left by the said James Hunter at the
Office of the Commissioners of Patents, with his Petition, on the
24th April 1871.
I, JAMES HUNTER, of Coltness Iron Works, in the County of Lanark,
North Britain, do hereby declare the nature of the said Invention
of "IMPROVEMENTS IN BLAST FURNACES," to be as follows, that is to say :-
This Invention relates to improvements in blast furnaces whereby
they are rendered more efficient, by raising the materials in the upper
part of the furnace to a higher temperature than obtains in existing
O arrangements of blast furnaces, thereby enabling a greater amount of
materials to be smelted; and it consists in providing the upper part
of the furnace with twyers or blast pipes through which a hot or cold
blast of air, or air and gas mixed together, is forced; which as it impinges

page_text: upon the newly charged materials ignites them, thereby raising their
temperature and driving off and burning the waste component parts,
and by so elevating their temperature prepares the materials to be more
quickly reduced in the lower parts of the furnace. In order to give
greater support to the materials in the upper parts of the furnace,
namely, at the part where the blast is forced in, a transverse arch with
openings at the sides to allow the materials to descend through is
provided, and it is preferred to make the arms or buttresses of the arch
hollow, and with perforations at the sides, in order to enable the blast
to be forced therethrough into the very centre of the charge, or in place
of making these arms or buttresses hollow, perforated tubes of a
refractory material may be employed, either above or below, or as
forming part of the said arch.
The arrangement referred to may be applied to either open or closed
topped furnaces, and openings with ducts are provided either below or
above, or below and above the part where the blast is injected, through
which either the whole or part of the unburnt gases are taken off to
heat the blast stoves.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said James Hunter in the Great Seal Patent Office ou
the 23rd October 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
'HUNTER, of Coltness Iron Works, in the County of Lanark, North
Britain, send grecting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her 2
Letters Patent, bearing date the Twenty-fourth day of April, in the year
of our Lord One thousand cight hundred and seventy-one, in the 35th
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said James Hunter, Her special license that 1, the
said James Hunter, my executors, administrators, and assigns, or such ¦
others as I, the said James Hunter, my executors, administrators, or
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, a

page_text: "
and Isle of Man, an Invention for "IMPROVEMENTS IN BLAST FURNACES,'
upon the condition (amongst others) that I, the said James Hunter,
by an instrument in writing under my hand and seal, should par-
ticularly 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 James Hunter, 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, reference being had to the accompanying
Drawings, and to the letters and figures marked thereon, that is to
say :-
My said Invention relates to improvements in blast furnaces whereby
they are rendered more efficient, by raising the materials in the upper
part of the furnace to a higher temperature, thereby enabling a greater
amount of iron ore to be smelted, and it consists in providing the
upper part of the furnace with twyers or blast pipes or flues through
which a hot or cold blast of air is forced in among the materials, which
air as it impinges upon the newly charged materials ignites the gas,
thereby raising their temperature and driving off and burning the waste
component parts, and by so elevating their temperature prepares the
materials to be more quickly reduced in the lower parts of the furnace.
For more effectually dispersing the air among the materials in the upper
parts of the furnace a transverse arch dividing the upper parts of the
furnace into divisions to allow the materials to descend through is
provided, and it is preferred to make the arms or buttresses of the arch
hollow, and with perforations in the sides in order to enable the blast to
be forced therethrough into the very centre of the charge as it passes
through the four divisions.
And in order that my said Invention may be properly understood,.
I now proceed more particularly to set forth the system, mode, or manner
in or under which the same is or may be used or practically carried into
effect, that is to say:―
Upon Sheet I. of the Drawings hereunto appended Figure 1 is a
vertical section and Figure 2 a horizontal section upon the line A, B,
Figure 1, shewing a closed top blast furnace constructed in accordance
with my Invention.

page_text: In the shaft C of the furnace at or near the bottom of the annular
flue A, a double transverse arch is formed, the radiating arms or
buttresses D of which being constructed hollow, whereby a passage d
is formed in each extending inwards to near the centre of the arch,
the outer end of each such passage communicating with an annular
flue or passage A formed in the masonry of the furnace. In each of
the arms or buttresses D, and on either side thereof, a series of openings e
are situated, which establish a communication between the passages d
and the body of the furnace. When the furnace is in operation a hot
or cold blast is forced through one or more openings a into the annular
flue A, and thence into the blast passages d, whence it passes through
the openings e, and spreads through the materials in the upper part of
the furnace, igniting the volatile combustible gases, which are then driven
off, and by elevating the temperature of the materials prepares them to
be more rapidly reduced in the lower parts of the furnace. The gases
usually known as "waste gases" which escape from the charge may be
taken off in an ordinary manner through one or more openings formed
in the upper part of the masonry B, or they may be withdrawn from
below the arch D, or partly from above and partly from below the arch D.
The openings and doors c are provided for the purpose of removing
any dust which may accumulate in the annular fluc A. A gallery or
staging g is by preference erected at that level, as shewn, round the out-
side of the furnace to admit of an attendant examining and cleaning the
flues from time to time.
It is to be understood that in lieu of construct the arms or
buttresses of the arch hollow so as to form twyers or blast pipes in
each as herein-before set forth, perforated tubes of a refractory material
may be employed either above or below or as forming a part of the
said arch for the purpose of conveying the blast to the centre of the
charge.
Under a modified arrangement of my improved blast furnace in
addition to the flues or passages & formed in the buttresses or arms D
of the transverse arch, and in order to give a greater distribution of the
blast over the materials, other sets of flues or passages may be employed
by means of building walls above each of the arms or buttresses D to
any height required, these walls being hollow and in communication
with an annular flue formed in the masonry or otherwise arranged so as
to admit of the blast being forced therethrough. An example of this
modified arrangement is illustrated upon Sheet 2 of the Drawings here:

page_text: unto appended, whereof Figure 1 is a vertical section, and Figure 2 a
horizontal section upon the line A, B, Figure 1. Above cach of the
buttresses or arms D of the transverse arch a hollow wall E¹ is built, the
flues or passages & formed in each being in communication with an
annular fluc A formed in the masonry, whilst from each of the flues d'
openings e¹ extend through the hollow walls E' and effect communication
between the flues & and the spaces E, Fig. 2, down which the materials
descend. The annular flue A is carried up to about the same height
as the hollow walls E¹, and in the masonry outside thereof one or more
openings c¹ is or are formed for the purpose of admitting the ends of
the blast pipe or pipes, which, however, are not shewn in the Drawings,
whilst in the masonry constituting the inner side of the annular flue
openings or perforations flare formed so as to establish a communi-
cation between it and the interior of the furnace whereby the blast is
distributed throughout the descending materials.
And it is further to be understood that although not shown upon the
Drawings the improvements constituting this Invention are equally
applicable to open as well as to closed topped blast furnaces.
Having now described the nature of my said Invention, and the
system, mode, or manner in or under which the same is or may be used,
I wish to observe in conclusion that I am aware that in the Specification
of Ferrie's Patent, No. 1888, A.D. 1868, a method is described of
forcing air into the retorts or chambers which contain the fuel separated
from the ore and flux acting upon the fuel only; I am also aware that
in the Specification of Barclay's Patent, No. 2551, A.D. 1870, provision
is made for forcing in air just above the charge so as to ignite a portion
of the gases escaping therefrom, and that in Barclay's Patent, No. 404,
A.D. 1871, means are described by which a portion of the gas is first
withdrawn from the furnace and then re-introduced with a portion of
air so as to burn in a neutral flame; also that a construction of the
upper part of a blast furnace similar to that shown at Sheet 2 of my
Drawings is also shown in the Specification of Barclay's last-mentioned
Patent; but what I consider to be novel and original, and therefore
claim as the Invention secured to me by the herein-before in part
recited Letters Patent is,-
First. The construction of blast furnaces having a transverse arch
with openings therein for enabling a hot or cold blast of air to be

page_text: distributed throughout the entire mass of materials in the upper part of
a blast furnace and so as to act on the whole of the materials, namely,
the ore, flux, and fuel, as herein-before described and shown upon the
annexed Sheet of Drawings, or any mere modification thereof.
Second. The use or employment of hollow walls above a transverse
arch so as to distribute a hot or cold blast of air, as distinguished from
a mixture of air and gas, through the materials in the upper part of a
blast furnace, as herein-before described and shown at Sheet 2 of the
Drawings. It is, however, to be understood that I make no claim to
the construction of a blast furnaco with such hollow walls.
In witness whereof, I, the said James Hunter, have hereunto set
my hand and scal, this Twenty-first day of October One thousand
eight hundred and seventy-one.
JAMES HUNTER.. (L.S.)