IMPROVEMENTS IN THE MANUFACTURE OF CRUDE OR PIG IRON
Year: 1882

page_text: LETTERS PATENT to James Moss Bennett of Glasgow in the County of
Lanark, North Britain, Metallurgist for an Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF CRUDE OR PIG IRON "
PROVISIONAL SPECIFICATION left by the said James Moss Bennett at the
Office of the Commissioners of Patents on the 14th July 1882.
JAMES MOSS BENNETT, of Glasgow, in the County of Lanark, North Britain,
Metallurgist, "IMPROVEMENTS IN THE MANUFACTURE OF CRUDE OR PIG IRON,"
This Invention which relates to improvements in the manufacture of Crude or
pig iron has for its object to prevent any of the products of the operations which
take place in a blast furnace from escaping or being led off at or near to the upper
part of such furnace or at any other point than in a zone situated between the
bottom twyers and the hearth or crucible wherein the reduced liquid metal and
slag are collected preparatory to the furnace being tapped so that the whole of the
products of the distillation which takes place at the upper part of the furnace as
well as the fluxes and reduced metal are all caused to pass through and re-act upon
each other in the hottest zone of the furnace prior to any of the gaseous or
vaporised or earthy or metallic products passing out of the furnace.
For the purpose of effecting these objects, the blast furnace is provided with a
series of twyers extending from the top. to the bottom or reducing zone, those
twyers in the neighbourhood of the reducing zone being preferably arranged at
closer intervals vertically than those extending from the boshes of the furnace
upwards. Each twyer is provided with a stop valve so as to take it out of action
when required and in this way any twyer or twyers can be brought into operation.
An annular, partly annular or other suitably shaped chamber is placed at or
around the escape openings at the lower part of the furnace into which the gaseous
or vaporised products pass and from which they are or may be led off for utilization
or they may be led to condensers, scrubbers, purifiers or equivalent apparatus for
separating and collecting the ammonia, or other products.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said James Moss Bennett in the Great Seal Patent Office on the
12th January 1883.
JAMES MOSS BENNETT, of Glasgow in the County of Lanark, North Britain
" IMPROVEMENTS IN THE MANUFACTURE OF CRUDE OR PIG IRON
"
My said Invention which relates to Improvements in the manufacture of crude
or pig iron has for its object to prevent any of the products of the operations
which take place in a blast furnace from escaping or being led off at or near to the
upper part of such furnace or at any other point than in a zone situated between
the bottom twyers and the hearth or crucible wherein the reduced liquid metal and
slag are collected preparatory to the furnace being tapped so that the whole of the
products of the distillation which takes place at the upper part of the furnace as
well as the fluxes and reduced metal are all caused to pass through and react
upon each other in the hottest zone of the furnace prior to any of the gaseous or
vaporised or earthy or metallic passing out of the furnace.
For the purpose of effecting these objects the blast furnace is provided with a
series of twyers extending from the top to the bottom or reducing zone those
twyers in the neighbourhood of the reducing zone being preferably arranged at
closer intervals vertically than those extending from the boshes of the furnace
upwards. Each twyer is provided with a stop valve so as to take it out of action
when required and in this way any twyer or twyers can be brought into operation.
An annular partly annular or other suitably shaped chamber is placed at or
around the escape openings at the lower part of the furnace into which the gaseous
or vaporised products pass and from which they are or may be led off for
utilization or they may be led to condensers, scrubbers, purifiers, or equivalent
apparatus for separating and collecting the ammonia or other products.
And in order that my said Invention may be properly understood I now proceed
more particularly to set forth the system inode, or manner in or under which the
same is or may be used or practically carried into effect reference being had to the
accompanying Drawings and to the Letters and Figures marked thereon, that is
to say,
Figure 1, is a part vertical section and part elevation of a blast furnace con-
structed according to my present Invention.
Figure 2, is a part plan and part horizontal section of the same.
Figure 3, is a part sectional elevation of the same taken on a line at right angles
to that on which Figure 1, is taken.
The blast furnace is charged from the top by the cover a, being raised from off
the charging hopper b, which is effected by the action of the counter-weighted
lever c, from whose bifurcations d, it is suspended by connecting links working at
their upper ends in slots in the said bifurcations. The material to be treated
within the furnace is then charged into the charging hopper b, and the cover a,
lowered into its normal position a sand joint may be made around the joint
formed by the same and the charging hopper b, to prevent the upward escape of
gas. The charge then contained within the charging hopper b, is lowered into the
furnace by the cone c, being lowered by means of the counter-weighted lever f,
from whose end it is suspended by the connecting link 9. whose upper
end works
in a slot within the lever f, and which passes through a gland and stuffing-
box h, provided on the cover a.-The gases and products of the operations which
take place within the furnace being unable to escape at the upper part of the
same, pass off through the openings A, (of which there are three in furnace
represented on the accompanying Drawing) which lead to the flues B, and are
forced therethrough by the hot-air blast which is led into the furnace by the

page_text: several rows of twyers as represented at i-The gaseous products, after passing
through the openings A, and flues B, may be led to condensers, scrubbers, purifiers
or equivalent apparatus for separating and collecting the ammonia, or other
products.
According to this Invention the ores of iron are reduced and descend to the
hearth or crucible C, from which the reduced liquid metal is tapped off at 7, the
slag being tapped off at n, the former of these being when necessary temporarily
closed with a clay or other suitable stopping and the latter may be similarly
treated or left continually open.
The herein before mentioned twyers i, are each provided with a stop-cock which
form the connection between the blast pipe D, and the twyer-pipes i, are at their
outer ends each preferably provided with a small window E, of mica or any other
suitable material to enable the attendant to inspect the action of the furnace
more satisfactorily.
The pipes D, as represented on the accompanying Drawing are three in number
and are each connected with the large blast pipe F, encircling the furnace and which
is carried on brackets G, and is in direct communication with the blast heaters.-
The three lowest rows of twyers i, are constructed as water-twyers i, are constructed
as water-twyers as represented at H, and a constant stream of water is circulated
around the same the necessary connections being provided for that purpose.
In constructing the furnace hereinbefore described it may be found necessary to
carry the upper part of the same upon the columns j, as shewn in which case the
mantel-platek, is built thereinto to rest upon the top of the columns. It may also be
necessary to form a water block over the top and down the sides of the opening A,
in which case any of the well known water blocks may be provided. The
openings A, and flues B, are strengthened in the ordinary manner of strengthening
Blast and other furnaces by the plates I, framing pieces J, and bolts K.
In order to explain the differences and advantages of my Invention for making
crude or pig iron as compared with the operations of a blast furnace as ordinarily
practised I first point out that in such ordinary blast furnace operations the
making of cast iron is effected in a tall stack or cupola furnace varying in
height from 30 feet to 110, feet, having a hearth or crucible, a bosh, varying in
width from 6 to 24 feet, shaft or body of the furnace and a charging head.-In
the hearth are two tapping holes, one for metal and one for slag or cinder, above
which are a series of twyers at one height for the introduction of blast or
atmospheric air-the products of combustion ascend and leave the furnace at or
near its top.
The operation is as follows: Iron ore being composed of oxide of iron and silica
or oxygen, metal and gangue, the first aim is to reduce this oxide to the metallic
state to effect which it must remain in contact with both the gaseous and solid
portions of the fuel for a period ranging from six to eighteen hours and upwards
at a temperature above 600° Fahrenheit after which it is carburized forming a
carburet of iron-which is easily melted, after which the flux, which is an alkali
(generally lime), forms with the silica a liquid slag or cinder through which the
reduced iron falls by virtue of the greater specific gravity to the bottom of the
furnace, that is to say into the hearth or crucible where it is tapped or run out
into pigs. The slag being lighter always floats on the top of the iron and is tapped
or run out at a higher point than the iron as occasion may require.
The top of the furnace is and must be comparatively the coldest part, and
the bottom or melting zone the hottest part of the furnace.-The element time
is most material for the action of the heat alone would only form a silicate of
iron or a heavily charged iron slag and no metal at all.
The stock or contents of the charges of the furnace is composed of ore, fuel,
and flux. Generally speaking the ore is roasted or calcined previous to being
placed in the furnace. The fuel, when wood or soft coal is used, is generally
charred, thus making charcoal or coke,

page_text: point for :-
First to cut away a "hanging," "chilling" or "scaffold "
Second-To correct a deficiency or surplus quantity of fuel.
The defect of working an ordinary furnace has been the inability of the founder
to determine the cause of any irregularity and even when found out the almost
total impossibility of obviating the same at once.
The advantages are:-(a) The entire control of the working of the furnace.
(b) Regulating of the grade of the product.
(c) Correcting any defect of working.
(d) The twyers running from bottom to top,
(e) by means of which the interior can be inspected.
(f) Use of unprepared fuel with its great economy.
(9) Calcining of the ore in the furnace.
(h) Saving of the combustible gases.
Having now described and particularly ascertained the nature of my said
Invention, and the system, mode or manner in or under which the same is or may
be used or carried into practical effect, I would observe in conclusion that I do not
limit myself to the precise form or detail of the furnace bereinbefore described
with reference to the accompanying drawing as I may vary the same in many
ways without departing from the nature of my said invention for instance I may
construct a furnace with one or more openings A, 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 blast furnace for the manufacture of crude or pig iron fitted with
vertical rows of twyers as set forth and wherein the gaseous products resulting
from the treatment of the materials as well as the materials themselves both pass
continuously in a downward direction through the furnace, the residual gaseous
products escaping through openings at the lower part of the furnace substantially
as and for the purposes hereinbefore set forth with reference to the accompanying
Drawing.
Second In a Blast furnace for the manufacture of crude or pig iron leading
the hot-air blast into the furnace at various levels, substantially as and for the
purposes hereinbefore set forth with reference to the accompanying drawing
In Witness Whereof, I, the said James Moss. Bennett have hereunto set my
hand and seal, this fifth day of December, in the year of our Lord One
thousand eight hundred and eighty-two.
TAR 15 DELLATEMM