IMPROVEMENTS IN THE MANUFACTURE OF STEEL FROM THE RESIDUUM OF PYRITE ROASTING FURNACES OR FROM IRON ORES
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by William Thomas Whiteman at the
Office of the Commissioners of Patents on the 14th July 1881. A com-
munication from abroad by Clément Martin, of Bleyberg-Montzen, in the
Kingdom of Belgium, Analytical Chemist.
WILLIAM THOMAS WHITEMAN, of No. 7, Staple Inn, in the County of Middle-
sex, Patent Agent. "IMPROVEMENTS IN THE MANUFACTURE OF STEEL FROM THE
RESIDUUM OF PYRITE ROASTING FURNACES OR FROM IRON ORES." [A commu-
nication from abroad by Clément Martin, of Bleyberg-Montzen, in the Kingdom of
Belgium, Analytical Chemist.]
The importance of the manufacture of steel from the residuum of pyrite roasting
furnaces will be readily understood when it is considered that in France, England,
Belgium, and Germany, upwards of eight thousand tons of pyrites are annually
consumed, producing, after roasting in the furnaces, upwards of five hundred and
twenty five thousand tons of peroxide of iron, containing less than one per cent. of
sulphur, and which constitutes, after being treated and purified according to this
Invention, a very rich iron ore, valueless for the manufacture of chemicals, and
which has hitherto been neglected by iron manufacturers on account of its friability,
which causes it to fall to a very fine powder and to obstruct the blast furnace, and
especially on account of the metalloids it contains which render the iron brittle.
The object of this Invention is to utilize the iron contained in the said residuum
by transforming it directly into steel of different degrees of carbonization, and it
consists of the processes hereinafter described for the treatment, purification, and
reduction of the said residuum. When the residuum of the pyrite roasting furnaces
contains more than one per cent. of sulphur, it should be roasted again in presence
or not of oxidizing or desulphurizing agents to deprive it of its sulphur.
The residuum of the pyrite roasting furnaces containing less than one per
cent. of sulphur is reduced to powder; it is then placed upon sheet iron plates
perforated with holes of about one twenty fifth of an inch in diameter, and is
washed in a trunk or vessel mounted upon fixed or shaking tables so as to enrich
it, or it may be simply washed or cleansed in cases or tanks through which a
stream of water is caused to flow so as to enrich the residuum by depriving it of
its earthly parts and of those which are soluble in water.

page_text: The residuum or ore thus prepared is then mixed with coal or suitable carbona-
ceous matter, in proportions varying according to the quantity of iron it contains
and the degree to which it is to be carbonized.
To the mixture of ore and coal is then added very unctuous clay and lime, or
any other like material capable of forming a very fusible flux in proportions
The
varying according to the physical state and the chemical nature of the ore.
mixture or mass thus obtained is moistened with water rendered alkaline or acid
as required, and then is converted into blocks or cakes by being subjected to
powerful hydraulic or other pressure in cylindrical or other moulds. The said
blocks or cakes having been dried are introduced into a furnace, hereinafter alluded
to as the "calcinating and reducing furnace," in which, they are for a suitable time
exposed to the influence of heat and a reducing atmosphere. The iron contained
in the said blocks or cakes under the influence of the elevated temperature in the
calcinating and reducing furnace is reduced, a portion of the lime combines with
the sulphur and phosphorous, whilst part of the unctuous clay agglutinates and
greatly hardens the mass and increases its density, and parts of the same are
scorified with the gangue and lime, forming with them a most fusible scoria or slag,
which is removed to the melting furnace in which the next operation is effected.
The next operation is carried on in a melting furnace (or other suitable apparatus)
heated by ordinary fuel, or in which the fuel is gasified and used in the state of
gas. The said furnace or apparatus, the concave sole of which has been previously
charged with the highly fusible scoria or slag produced in the calcinating and
The blocks
reducing furnace hereinbefore described is heated to a bright red heat.
or cakes, also heated to a bright red heat, are introduced into the bath of melted
scoria or slag by means of a self acting duct without any loss of heat, and sink
into and are immersed in it by their own weight.
Under the influence of the elevated temperature of the furnace from which free
oxygen is excluded, the reduction of the iron is completed, whilst at the same time
it is carbonized by means of the surplus coal which has not served for the reduction.
The gangue forms with the lime and clay, forming part of the blocks or cakes
introduced into the bath, a basic scoria or slag, which entirely covers the melted
metal and preserves it from oxidation, and owing to the silica it contains and
also to its chemical properties, it becomes a powerful agent of desulphuration and
dephosphoration. When all the chemical reactions hereinbefore described; have
been effected the operation is terminated, and the scoria or slag having been
removed from the furnace, the steel is run into suitable ingot moulds for use as
required.
The processes and operations herein before described are also applicable to the
manufacture of steel from ordinary iron ores.