IMPROVEMENTS IN TREATING CAST IRON SO AS TO IMPROVE AND SECURE UNIFORMITY OF QUALITY
Year: 1870

page_text: LETTERS PATENT to William Henderson, of 97, Buchanan Street,
in the City of Glasgow, and County of Lanark, for the Invention
of "IMPROVEMENTS IN TREATING CAST IRON SO AS TO IMPROVE AND SECURE
UNIFORMITY OF QUALITY."
Sealed the 13th January 1871, and dated the 2nd November 1870.
PROVISIONAL SPECIFICATION left by the said William Henderson at
the Office of the Commissioners of Patents, with his Petition, on
the 2nd November 1870.
I, WILLIAM HENDERSON, of 97, Buchanan Street, in the City of
Glasgow, and County of Lanark, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN TREATING CAST IRON SO AS TO IMPROVE
AND SECURE UNIFORMITY OF QUALITY," to be as follows:-
These improvements have for their object the correction of the
irregularities of the ordinary working of the blast furnace, and the

page_text: securing by the means proposed a uniform production of the highest
quality of pig iron produceable by the nature of the ore fuel and the
action of the blast furnace at its best. It is a well-known fact that
the same furnace under the most careful management will suddenly
cease to produce the best quality of iron, and will continue to make for
irregular periods what is technically known as Nos. 2, 3, and 4, instead
of No. 1.
The object of these improvements is to correct this irregularly and
secure without fail the quality of make desired. To accomplish this
object I proceed as follows:-Immediately in front of the tap hole of
the blast furnace, and at a convenient distance to allow sufficient space
for working this part of the furnace without danger or inconvenience
to the workman, I construct a receiver which I prefer to have in the
form of a reverberatory furnace with the means of heating it to an
intense white heat if required. This may be accomplished by an
ordinary coal fire, or by gas, or any other means that will most econo-
mically produce the requisite heat. This furnace or receiver I prefer
to have of sufficient capacity to hold the whole of the metal produced
at the ordinary periods of tapping the furnace, but it may if convenient
be only half that size or less and the furnace be tapped the oftener..
The principal distinguishing feature between Nos. 1, 2, 3, and 4 of any
particular brand of iron is the quantity of carbon they contain, No. 1.
containing the largest proportion, and the principal object of these
improvements is to compel the iron to absorb more carbon, (if it has not
enough already,) and whilst it is in a fluid state, and before it is allowed
to pass to the ordinary sand casting bed.
To ensure the rapid and certain absorption by the molten metal of the
requisite amount of carbon I construct the bottom and part of the sides
of the furnace or receiver of solid blocks of carbon. These are very
conveniently made by grinding in an ordinary mortar mill best hard
solid coke to a coarse powder, and then adding coal tar till the mixture
assumes a stiff uniform consistence like stiff clay or mortar. It is then
rammed into cast-iron moulds constructed so as to form the required
block and held together by clamps and wedges. For a square block
there will be a bottom and top plate, and two L's which will determine
the thickness and size of the block. The mould is completely filled

page_text: and placed in an oven or heating furnace and subjected for several
hours to a red heat until all gases have ceased to come off. The blocks
are then withdrawn and quenched with water, and are then fit for
building into their place. By this means, blocks of any size or shape,
and of great solidity and endurance may be made. The whole bottom
of the furnace of the receiver is constructed of these blocks, which
should be at least 18 inches thick, and the sides of the furnace or
receiver also up as high as the molten metal will reach when the
furnace or receiver is filled. To further increase the contact of the
metal with carbon, I cover the whole surface of the molten metal with
(preferably) anthracite coal, charcoal, or coke. The fire is simply used
to maintain the fluidity of the metal or to increase the heat as much as
is necessary to ensure the absorption of the requisite amount of carbon
in the space of time allowed between the castings. The upper portion
of the walls and the roof, and fire-place, or fire-places of the furnace
are constructed of the best fire-bricks in the usual manner, only the
bottom and portion of the sides as high as the metal reaches are solid
carbon. Before heating the furnace, the bottom and sides should be
protected with the anthracite, charcoal, or coke, mixed with crushed
furnace slag, which is to form the covering. When the furnace has
reached the requisite heat it is filled with metal from the blast furnace,
and will at once commence to absorb carbon. A sample taken at intervals
by a ladle and cast into a bar will when fractured show the quality
of the iron. When the desired point has been reached the metal is
tapped into sand and formed into pigs in the usual manner.
The receiver or furnace is kept in constant repair, and the consumption
of carbon supplied either by fettling between the charges with the ground
coke and tar, or by using bituminous coal dust, which is heated till soft
and pressed by an iron ladle where required.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Second day of November, in the year
of our Lord One thousand eight hundred and seventy, in the thirty-
fourth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said William Henderson, Her special licence
that I, the said William Henderson, my executors, administrators, and
assigns, or such others as I, the said William Henderson, 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
TREATING CAST IRON SO AS TO IMPROVE AND SECURE UNIFORMITY OF QUALITY,"
upon the condition (amongst others) that I, the said William Henderson,
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 immediately
after the date of the said Letters Patent.
NOW KNOW YE, that I, the said William Henderson, 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 thereof, that is to say :-
These improvements have for their object the correction of the
irregularities of the ordinary working of the blast furnace, and the
securing by the means proposed a uniform production of the highest
quality of pig iron produceable by the nature of the ore fuel and the
action of the blast furnace at its best. It is a well-known fact that
the same furnace under the most careful management will suddenly
cease to produce the best quality of iron, and will continue to make
for irregular periods what is technically known as Nos. 2, 3, and 4,
instead of No. 1.
The object of these improvements is to correct this irregularity and
,secure without fail the quality of make desired. To accomplish this
object I proceed as follows:-Immediately in front of the tap hole of
the blast furnace, and at a convenient distance to allow sufficient space

page_text: for working this part of the furnace without danger or inconvenience to
the workmen, I construct a receiver, which I prefer to have in the form
of a reverberatory furnace with the means of heating it to an intenso
white heat if required. This may be accomplished by an ordinary coal
fire, or by gas, or any other means that will most economically produce
the requisite heat. This furnace or receiver I prefer to have of sufficient
capacity to hold the whole of the metal produced at the ordinary periods
of tapping the furnace, but it may if convenient be only half that size
or less and the furnace be tapped the oftener.
The principal distinguishing feature between Nos. 1, 2, 3, and 4 of
any particular brand of iron is the quantity of carbon they contain,
No. 1 containing the largest proportion, and the principal object of these
improvements is to compel the iron to absorb more carbon, (if it has
not enough already, and whilst it is in a fluid state, and before it is
allowed to pass to the ordinary sand. casting bed..
.
To ensure the rapid and certain absorption by the molten metal of
the requisite amount of carbon I construct the bottom and part of the
sides of the furnace or receiver of solid blocks of carbon. These arc
very conveniently made by grinding in an ordinary mortar mill best
hard solid coke to a coarse powder, and then adding coal tar till the
mixture assumes a stiff uniform consistence like stiff clay or mortar.
It is then rammed into cast-iron moulds constructed so as to form the
required block and held together by clamps and wedges. For a square
block there will be a bottom and top plate and two L's which will
determine the thickness and size of the block. The mould is completely.
filled and placed in an oven or heating furnace and subjected for several
hours to a red heat until all gases have ceased to come off. The blocks
are then withdrawn and quenched with water and are then fit for
building into their place. By this means blocks of any size or shape
and of great solidity and endurance may be made.. The whole bottom
of the furnace or receiver is constructed of these blocks, which should
be at least 18 inches thick, and the sides of the furnace or receiver also
up as high as the molten metal will reach when the furnace or receiver
is filled. To further increase the contact of the metal with carbon I
cover the whole surface of the molten metal with (preferably) anthracite
coal, charcoal, or coke. The fire is simply used to maintain the fluidity
of the metal or to increase the heat as much as is necessary to ensure,

page_text: the absorption of the requisite amount of carbon in the space of time
allowed between the castings. The upper portion of the walls and the
roof, and fire-place, or fire-places of the furnace are constructed of the
best fire-bricks in the usual manner, only the bottom and portion of
the sides as high as the metal reaches are solid carbon. Before heating
the furnace the bottom and sides should be protected with the anthracite,
charcoal, or coke, mixed with crushed furnace slag, which is to form
the covering. When the furnace has reached the requisite heat it is
filled with metal from the blast furnace, and will at once commence to
absorb carbon. A sample taken at intervals by à ladle and cast into
a bar will when fractured show the quality of the iron. When the
desired point has been reached the metal is tapped into sand and formed
into pigs in the usual manner...
By constructing the receiver of sufficient capacity to allow of sufficient
time between the charges further improvements may be produced in
the cast iron. Cast iron not only increases in value by the increase of
the carbon, but by the decrease of the sulphur, silicon, and phosphorus.
Silicon and probably sulphur can be much reduced, for instance, by
metallic manganese. If the interval between the charges is sufficiently
long a mixture of carbonate of manganese or oxide of manganese and
oxide of iron with anthracite coal or bituminous coal might be reduced
to the metallic state at a comparatively low heat in the bed of the
receiver or furnace and the cast metal from the blast furnace ran on to
it. In like manner other substances may be employed to remove the
other impurities or to reduce their proportion and thereby improve
the quality of the iron.
The receiver or furnace is kept in constant repair and the consumption
of carbon supplied either by fettling between the charges with the
ground coke and tar or by using bituminous coal dust which is heated
till soft and pressed by an iron ladle where required.
And having now described the nature of my said Invention, and in
what manner the same is to be performed, I declare that I claim, the
method herein described of increasing the carbon in cast iron by
introducing a furnace or receiver between the blast furnace into which
the fluid metal is run direct from the blast furnace, such receiver being
capable of being heated to the requisite degree of heat to maintain the
metal in a proper state of fluidity for such time as may be required, and

page_text: such receiver having also a solid carbon bottom, and the molten metal
being also covered with a layer of coke, anthracite coal, or other suitable
carbonaceous matter, substantially as described.
In witness whereof, I, the said William Henderson, have hereunto
set my hand and seal, this Twenty-eighth day of April One
thousand eight hundred and seventy-one.
WN. HENDERSON. (L.S.)