IMPROVEMENTS IN THE MANUFACTURE OF IRON
Year: 1879

page_text: LETTERS PATENT to John Howard Kidd, of Wrexham, in the County of
Denbigh, Engineer, and Jonathan Green, of Brymbo, in the said County,
Blast Furnace Manager, for the Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF IRON."
Sealed the 27th February 1880, and dated the 10th October 1879.
PROVISIONAL SPECIFICATION left by the said John Howard Kidd and
Jonathan Green, at the Office of the Commissioners of Patents on the 10th
October 1879.
JOHN HOWARD KIDD, of Wrexham, in the County of Denbigh, Engineer, and
JONATHAN GREEN, of Brymbo, in the said County, Blast Furnace Manager.
"IMPROVEMENTS IN THE MANUFACTURE OF IRON."
Our Invention relates to the manufacture of iron in blast furnaces, and its object
is to so regulate the action of the furnace that the production will be of a uniform
quality, and so that any of the ordinary qualities may be produced at will, and our
Invention consists in ineans and arrangements for regulating the temperature of the
blast and adjusting such temperature and blast so as to produce iron of the required
quality. The blast is produced, conveyed, heated, and passed into the furnace in
the ordinary manner, but between the receiver or reservoir into which the blast is
pumped, and the pipe distributing the blast to the tuyeres, a pipe is arranged in
which there is a valve with an index so that more or less cold blast can be admitted
to the hot blast in the tuyere supply pipe as desired, and by opening this valve
more or less the desired quality of iron will be produced, taking care that the
engine shall pump a constant and uniform supply of air, and that it shall be
uniformly heated.
Our Invention further consists in arranging a thermometer or other heat
measurer in the pipes supplying the tuyeres, and opening or closing the valve for
cold blast, until the desired temperature is attained; and our Invention further
consists in selfacting arrangements between the thermometer and cold blast valve
which will open the valve to admit more cold air as the temperature rises, and
close it to admit less cold air as the temperature falls, thus obtaining a blast of any
desired uniform temperature to suit the quality of iron to be produced. In place
of cold air hydrogen gas is or may be pumped through the pipe before mentioned,
alone or mixed with cold air to mix with the hot blast.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Howard Kidd and Jonathan Green in the Great Seal Patent
Office on the 9th April 1880.
JOHN HOWARD KIDD, of Wrexham, in the County of Denbigh, Engineer, and
JONATHAN GREEN, of Brymbo, in the said County, Blast Furnace Manager.
"IMPROVEMENTS IN THE MANUFACTURE OF IRON."
"
In the manufacture of iron in blast furnaces by the ordinary mode of working
each desired quality is obtained by adjusting the "burden as it is termed, viz.,
the proportion of fuel and materials, and this burden is varied according to the
quality of the iron desired, but even when the burden has been adjusted to produce
the quality of iron required according to the best judgement of the manager, the
products of each casting will not be uniform but will vary in quality, that is, there
may be two, three, or more qualities or numbers of iron in each casting, and it has
been hitherto impossible by any known means to make each casting of iron entirely
of the same quality.
It is the object of our Invention not only to attain a uniformity of quality in
each casting, but to make such casting of any quality lower than the average quality
which the iron would cast by the ordinary process; for instance, should the iron
about to be cast average, say No. 2 in quality, we can by our Invention make it
No. 3, 4, or other lower quality that may be desired.
In working the blast furnace we charge with a "burden" that we know from
experience will on an average produce in the ordinary mode of working the furnace
a rather better quality than the quality desired, and we arrange so that the cold air
blast from the pumping engine can be taken direct to the pipe supplying the
tuyeres without first passing through the stoves for heating the blast, and by this
means by admitting the cold blast into the tuyere supply pipe direct, we have a
means of modifying at will the temperature of the blast without reducing the heat
of the stoves which rather tend than otherwise to get more heated while the cold
blast is in usc.
After considerable experience we find the best mode of working to accomplish the
objects of our Invention is to allow the furnace to be worked in the ordinary
manner, that is with the full hot blast at its highest temperature, and some time
before casting or tapping the metal from the furnace we turn on the cold blast into
the tuyere supply pipe, and this reduces the temperature of the blast, and we keep
on this cooler blast until we see that the scoria, cinder, or slag, which escapes
from the furnace corresponds with the quality of iron desired, and then the cold
blast is shut off.
Every skilled furnace man is able to tell from the character of the scoria or cinder
which is being discharged from the furnace what quality or number the iron will
be, and it is by noting the quality of the scoria or cinder which flows out between
the times for casting that the furnace man will know what quality of iron is in the
hearth of the furnace, and if there are several, the using of the cold blast according
to our Invention, just before casting, will bring these different qualities of iron all
to one uniform quality, and if such quality of iron is better or of a higher number
than required, then by continuing the cold blast for a longer or shorter time the
desired quality of iron will be obtained, which will be known when the scoria or
cinder corresponding to the desired quality of iron begins to be discharged.
It will thus be seen that the result of reducing the temperature of the blast
before casting, in which our Invention consists, is that the iron in the hearth of the
furnace is converted into one of uniform quality, and if the cool blast is continued
long enough the iron to be cast is reduced to a lower quality or to a lower number
if desired.
The time during which the cool blast must be in operation before each casting or
tapping of the furnace will vary from about 15 to 30 minutes (depending upon the

page_text: quantity of cold blast admitted), and if the iron is to be reduced in quality or to a
lower number in quality, more time will be necessary the greater the extent of the
reduction in quality or number desired.
By our improved mode of working blast furnaces, a cleaner, stronger, and tougher
iron is obtained, and we are enabled at the same time to test the state of the furnace
and know better how to regulate its burden and working.
If we find when the cold blast is turned on that it takes a comparatively long
continuance of this reduced temperature of blast to make the desired change in the
character of the cinder or scoria, this indicates that the furnace will bear more
burden, if on the contrary the change in the character of the cinder is effected by a
comparatively short continuance of the cool blast, then we know that the burden
is right.
We also find the putting on of the cold or cooler blast for a time as described
will tend to correct the action of the furnace when it is sluggish, and will not take
the blast from having too much lime.
When we are producing, and wish to continue to produce, any given quality of
iron, we keep the quantity of the blast and its temperature and the burden of the
furnace as uniform as possible.
Our Invention will be found advantageous in making Bessemer metal direct from
the blast furnace, as we can regulate the furnace, and are able with certainty to
produce the uniform quality desired from one blast furnace.
The accompanying Drawings by Fig. 1, a partial elevation, and Fig. 2, a partial
plan, will illustrate the arrangements for carrying out our Invention.
a represents part of the exterior of a blast furnace; b, part of the pipe supplying
the tuyeres; c represent portions of some of the stoves for heating the blast; d, the
pipe or reservoir into which the blast is received from the pumping engine; c¹, pipes
between the main blast pipe and the stoves; and c³, pipes between the stoves
and the tuyere supply pipe 6; e is a pipe connected with the main blast pipe d.
In the pipe e there is a valve e¹, by which the cold blast can be turned on
and off.
The pipe e is connected with a pipe e², concentric with the tuyere supply pipe b,
with which it has junctions at intervals.
The size of the pipes e and e³ is not important if they are large enough.
If the cross sectional area of the bore of the cold blast pipe e is the same as one
of the stove pipes c¹ and the pipe e², half the area, they will not be too large, as the
quantity of cold blast passed through can be regulated by the valve e', and if this
(as we prefer) is made with an index to show to what extent the valve is open, the
furnace man will be able to open the valve before casting to that extent which he
finds necessary and best by experience.
We have now particularly described the nature of our said Invention, and the
mode of carrying the same into effect, and claim as our Invention,―
The working of blast furnaces for the manufacture of iron by the introduction of
cold blast, or a cooler blast than is used for the ordinary working of the furnace for
a time before each casting of the metal, to make all the metal about to be cast of
the same uniform quality or number, or all the metal to be cast of a uniform lower
number or quality as may be desired, substantially as hereinbefore described.
In witness whereof, we, the said John Howard Kidd and Jonathan Green,
have hereunto set our hands and seals, this Sixth day of April, in the year of
our Lord One thousand eight hundred and eighty.