IMPROVEMENTS IN THE MANUFACTURE OF CAST STEEL
Year: 1857

page_text: application for Letters Patent was not given within the time prescribed
by the Act.)
PROVISIONAL SPECIFICATION left by George Tomlinson Bousfield at the
Office of tho Commissioners of Patents, with his Petition, on the
15th December 1857.-A communication from S D Diego Mason, of
Bilboa.
I, GEORGE TOMLINSON BOUSFIELD, of Loughboro Park, Brixton, in the
County of Surrey, do hereby declare the nature of the Invention for
"IMPROVEMENTS IN THE MANUFACTURE OF CAST STEEL," to be as follows:-
I granulate cast iron (pig metal, fine metal, &c.) by any known method,
although I prefer melting it and running it into water; or instead of
granulating the cast iron I run it into thin plates, by pouring the fluid metal
on to a cold metal plate, or by other means calculated to effect the same
object. When I use granulated metal I sort it by means of sieves into
different sized grains, for a purpose that will be seen hereafter, although this
is not absolutely necessary. I mix the granulated metal with a quantity, say,
one-fourth its weight of oxide of iron, or iron ore, or oxide of manganese, or a
carbonate of lime, or powdered brick or clay, or in fact one of a variety of
substances capable of yielding oxygen at a red heat, and of keeping the metal
grains or plates divided under the circumstances about to be described, but
I prefer the oxidized ores of iron and manganese. I place the mixture on the
bed of a large reverberatory furnace, which may be similar in size and shape
to a copper ore calcining furnace, such as they are used in South Wales, and
capable of holding a charge of some 3 or 4 tons. I submit this charge to a
moderate red beat during 24 or more hours, according to the size of the grains
of cast iron; if the grains are very small a less number of hours than 24 might
be sufficient. I occasionally turn over the charge in order to submit the whole

page_text: of it to an equable temperature; the reactions that take place during this
operation are the following:-Tho carbon and silicium contained in the cast
iron are completely oxidized to the centre of the grains. The carbon escaping
as carbonic acid gas, and the silicium remaining in the metal as silicic acid or
silica; the iron is now in the form of malleable iron, and may be flattened out
under the hammer, under certain circumstances to be hereafter described.
I do not continue the oxide cementing operation so long as to oxidize all the
carbon contained in the cast iron; the amount of carbon left in the metal cau
be regulated at the will of the operator. The principle of the operation here
described, is that known and commonly practised in the manufacture of what
are called "malleable cast-iron goods." In some cases I make no use of an
intermediate agent for communicating the oxygen required in this operation,
but I proceed at once to calcine. the granulated metal, thereby producing a
quantity of oxyde of iron at its surface. Having in either case removed the
charge from the furnace, I proceed to separate the oxyde or other material
used as an oxidizing agent by roughly grinding it under a Chilian mill, and
then separating the powdered oxide by means of a sieve; by these or similar
mechanical means I obtain the metal in a clean state and free from the
adhering oxidizing agent. When I use the cast iron in plates, and in any
form not granulated, I prefer another method of carrying out the oxide
cementing process. Into a number of earthenware or cast-iron boxes I place
alternate layers of tho cast metal and the oxidizing agent; these boxes or pots
I-pilo up in a furnaco similar to those used for baking bricks or pottery, and
I raise them all to a moderate red heat. I keep the furnace at a heat sufficient
to cause the oxydation to penetrato partially or wholly to the centre of the
metal, as the case may require, which time will be in the ratio of tho
thickness of the pieces of metal operated on. When the quantity operated
upon may be 30 or 40 tons this operation will require several days, including
the cooling of the furnace; in order to effect the discharge of the boxes,
I take a quantity of the metal thus prepared, say 43 lbs. weight, I mix with it
a certain quantity of carbonaceous matter, I place the metal in a common steel
inelting-pot, and I submit it to the usual heat with the usual precautions for
obtaining cast steel; a certain quantity of carbon combines with the metallic
iron, melts and forms tho cast steel. In order to facilitate the completo
separation of the silica mixed with the iron, I mix with the carbonaceous
matter a small quantity of oxyde of manganese, or a basic silicate (preferably
one containing oxide of manganese, lime, magnesia, and alumina), but I
greatly prefer the oxydo of manganese, of which I find that 3 or 4 per
cent. is sufficient to absorb all the silica that may be contained in the iron.

page_text: I consider this to be the principal use of the oxide of manganese, as the
protoxide of this metal is not reduced to the metallic state except at an
exceedingly high white heat. A great variety of substances yielding carbon
directly or indirectly may be used in this operation and in various proportions,
such as charcoal, resins, pure coal, starch, sawdust, pitch, prussiate of potash,
Prussian blue, sugar, lamp black, &c. I have made use of the two latter in the
following proportions:- per cent. of lamp black, and one per cent. of sugar
finely pulverized; and when I use oxide of manganese I mix this latter with
the two former in very successful operations. I have made use of three and
four per cent. black oxide of manganese mixed with the above proportions of
carbonaceous matters; this mixture is sprinkled among the grains of metal so
as to be tolerably well mixed with it before placing it in the melting pot.
For producing hard highly carbonized steels I make use of a larger proportion
of carbonaceous matter, in fact it may be used in such quantity that it floats
over the melted metal and inflames when the cover is removed from the pot.
I have in no case found that the carbon is absorbed in such quantity as
to produce a cast iron or in fact any other substance than a true steel. This
is the process which I use more especially when I heat impure cast iron
containing a notable quantity of silicium. When I make use of a pure material
such as cold blast charcoal iron, I modify the process as above described, that
is to say, I do not carry the oxide cementing process on the cast iron so far
forward as to liberate all the carbon contained in the cast iron, but I leave in
the centre of the granulated metal or plates such a quantity of carbon as
when it is submitted to a melting heat a steel is produced in the same
manner as when the carbonaceous matter is mixed directly as above described.
I also in this case prefer using a small quantity of oxide of manganese or a
basic silicate to absorb the silica contained in the metal.
I also carbonise the malleable cast iron produced during the first part
of the process by submitting it to a cementing process in every respect similar
to that commonly used for producing blistered steel from bar iron, by placing
it in boxes or pots mixed with carbonaceous matters and keeping it for a
considerable time at a red heat, in this case I make use of a lower tempera-
ture than is commonly used in the operation for producing blistered steel,
whereby I completely prevent the reduction of the silica or silicic acid (mixed
with the metal) to the state of silicium.