IMPROVEMENTS IN THE MANUFACTURE OF IRON AND. STEEL,. AND IN THE APPARATUS EMPLOYED THEREIN and
Year: 1868

page_text: PROVISIONAL. SPECIFICATION left by George Henry Benson and
William George Valentin at the Office of the Commissioners of.
Patents, with their Pétition, on the 17th December 1868..
We,, GEORGE. HENRY BENSON, of Staleybridge, in. the County of
Chester, Engincer, and WILLIAM GEORGE VALENTIN, of the Royal-
College of Chemistry, Chemist, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF IRON AND. STEEL,.
AND IN THE APPARATUS EMPLOYED THEREIN," to be as follows:-
Our Invention of improvements in the manufacture of iron and steel"
relates to a mode of and apparatus for mixing, and. fusing together irons
of various qualities for the purpose of producing steel or wrought iron
applicable to various useful purposes for which steel. or wrought iron of.
the ordinary manufacture is usually employed..
The production of cast steel by fusing together malleable or wrought
iron, and cast iron or pig iron on an open hearth or furnace basin is not
new, as several Patents have been granted for processes based on this.
principle, the first of which was granted to Josiah Marshall Heath, dated
August Fourth, One thousand eight hundred and forty-five, No. 10,790;

page_text: but we believe that this and other subsequent processes for producing
steel by the mixture of malleable iron with molten cast iron were not
commercially successful, also that a kind of soft steel containing a low
per-centage of carbon and approaching malleable or wrought iron as
well as wrought iron itself were never produced in masses kept liquid
in a furnace or run, and cast into ingot moulds with commercial success,
owing to the difficulty of keeping the mixture of irons at a sufficiently
high temperature to maintain it in a fluid state.
We have discovered that the required temperature may always be
maintained if the furnace be heated by a combination of highly heated
combustible gases and a blast of heated air introduced and maintained
therein under pressure, so as to prevent the ingress of the external air
through any of the doors, cracks, crevices, or other openings in the
furnace, and which air-would-lower_the_temperature of the furnace
and cause the molten iron to thicken. We are thus enabled to effect
the melting of the metal in a more effectual and economical manner
than heretofore, and moreover to control the operation thoroughly and
to accelerate the melting of the metals, because we are able to avoid
any inequality in -the-flame or intermittent lieat. And we would here
observe that for the generation of the combustible gases to be-used-for-
the purposes of our Invention we prefer to use the improved gas
generator or apparatus for which we have applied for Letters Patent
concurrently with this application.
In carrying out our Invention we construct a short reverberatory
furnace in form something like an ordinary puddling furnace, which is
heated by a mixture of combustible gases and air under pressure. This
furnace consists mainly of a hearth or basin nearest to the side from
which the flame from the combustible gases enters the furnace for the
melting down of the pig iron, and of one or two hearths or chambers on
the side where the flame passes out of the furnace for heating the scrap
wrought iron or other suitable wrought iron which we mix with the
pig or cast iron that is melted in the body of the furnace. The hearths
or chambers for heating the scrap wrought iron previous to its intro-
duction into the melting basin may be constructed one underneath
another, and heated either by the gases passing off from the melting
chamber or by a separate supply of combustible gases. At the end of
the scrap iron heating chambers we prefer to construct a bridge or wall
of greater height than the bridge between the principal melting basin

page_text: and the heating chambers, so that the heated gases and flame from the
former will pass over the scrap or wrought iron or other suitable
malleable irons in the heating chamber and will not impinge thereon.
The bottoms of the melting and heating chambers are formed of hollow
iron boxes, through which air is made to pass in order to keep them
from being destroyed by the heat. Upon these metal boxes we put a
layer of highly refractory material, such as fire-bricks, ganister bricks,
organister well rammed down; a thin layer of pulverized silica is next
fused thereupon into a pasty mass and fresh quantities of silica are added
and fused until the whole has become melted into a compact quartz-like
layer or bottom of from 4 to 12 inches in thickness. When the desired
thickness has been obtained and the final fusing thoroughly effected
the siliceous mass should be allowed to get nearly cold, when it may be
faced by melting small pieces of scrap iron placed all over the furnace
bottom under a reducing flame.
Hoppers provided with double doors, valves, or slides are adapted to
the sides of the furnace for the purpose of charging in the metal bars,
scrap iron, or other suitable metal. Tapping holes are also provided for
running off the slag and for discharging the molten metal into suitable
receptacles. The hole for discharging the metal from the furnace
is made at a part of the wall which is cut away or bevilled, so that
a ladle or moveable ladle furnace may be brought close under to receive
the molten metal. As the highly decarbonized metal which we produce
is liable to get stiff if cold air is allowed to come in contact with it, we
construct the ladle furnace in the form of a close vessel, mounted on
wheels for the convenience of transport, and provided with an opening
or openings, through which heated gases and blast from the furnace or
from any other source may be blown or introduced into the interior for
the purpose of keeping out the cold air and keeping up the temperature
of the metal until it is run into the ingot mould.
We operate practically by first getting up an intense heat in the melting
chamber or basin by means of the combined blast under pressure so as
to melt down the pig iron very rapidly. We thus avoid oxidation and
consequent loss of metal as much as possible and obtain a clear metal
bath. As the steel, wrought iron, or other suitable admixture requires a
much greater heat in order to melt it down we heat it first in the heating
chamber or chambers by the spent heat, or by means of a separate flame
or flames previous to its introduction into the metal bath. In con-

page_text: sequence of the gases being under pressure we are able to effect these
objects without cooling the furnace by any indraught of cold air on
opening the charging door for the introduction of the tools for removing.
tlic scrap wrought iron over the fire-bridge into the molten metal bath..
For the same reason we can melt down the wrought iron far more
rapidly and uniformly until by one or by repeated introductions of scrap
iron, steel, or other partially or wholly decarbonized iron the bath has
undergone the required amount of decarbonization, and the metal been
converted cither into hard or soft steel, or into a so-called homogeneous.
iron.
We are enabled to make a kind of steel approaching wrought iron,
such as cannot be made by the well-known Bessemer process, since a
more intense heat is required to keep such steel in a fluid condition, and
because even a slight decrease in the temperature of the flame chills it
and-renders.it unfit for the purpose of casting in moulds or ingot forms,
and gives rise-to-loss from skulling. The flame being completely under
control and of a steady and non-intermittent nature, we are enabled to
urge the heat of the furnace in a much shorter time to a hitherto
unattained degree and to make a metal that is nearly decarbonized.
This metal, which is practically wrought iron, we are enabled to keep in
a perfectly liquid state, and to cast it into ingots or work it up into-any-
articles for which wrought iron has hitherto been employed.