Improvements in or relating to the Utilisation of Waste Products from Metallurgical Furnaces and the like.
Year: 1898

page_text: Date of Application, 4th Jan., 1898-Accepted, 5th. Mar., 1898
.
Improvements in or relating to the Utilisation of Waste Products
from Metallurgical Furnaces and the like.
(A communication from HERMAN L. HARTENSTEIN, Manufacturer, of Bellaire,
Belmont County, Ohio, United States of America, and GEORGE A. WEBER,
Manufacturer, of 81st and Wallace Streets, Chicago, Illinois, United States of
America).
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of Middlesex,
Chartered Patent Agent, do hereby. declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
-
There is so comparatively little use for the slag or ainder resulting from the
reduction of iron-ore in a blast-furnace, that it is practically a waste-product, the
disposal of which is a problem becoming more and more serious in connection with
blast-furnace practice.
The object of this invention is to enable this waste-product to be manufactured
into a valuable commercial compound, that shall be useful in various chemical
and manufacturing processes and especially by reason of its chemical composition,
in the manufacture of gas in much the same manner that acetylene gas is evolved
from calcium carbide by bringing it into contact with water.
To this end this invention consists in the process employed to accomplish my afore-
said object, namely of mixing with the slag a suitable proportion of carbonaceous
material and subjecting the mixture to the action of an electric current, in the
circuit of which the mixture is included, as a part thereof. This statement of
my process expresses it in its broadest sense. In practicing it, however, it involves
certain details, hereinafter pointed out. Moreover it is subject to certain modifica-
tions, involving the treatment of the slag while primarily in a molten condition, or
in the condition in which it is discharged from the blast-furnace; the treatment
thereof when molten after it has been solidified by cooling; and the use with the
treatment of the slag, in either condition, primarily, of a suitable reducing gas.
The apparatus that has been devised, is best adapted for use in practicing this
improved process, is illustrated in the accompanying drawings, in which:-
Figure 1 is a view in cross-sectional elevation, partly broken, of this improved
converting apparatus; Figure 2, a view of the same in sectional side elevation;
Figure 3, à bottom plan view of the converter with the pipe-inclosing box removed;
Figure 4, a cross-sectional view of a coke-feeding detail; and Figures 5, 6º, 5º
and 5° are sectional views of the converter-chamber showing it in the different
positions to which it is adjusted in use.
g+
A is the improved converter-chamber, preferably of the shape illustrated, with
the straight side walls and end-walls r¹, the latter flaring from a rounded base a,
which connects them, the walls being connected from their outer ends by a top
formed of three sections 4 and 5, in angular relation to each other; and between
the top-section and the end-wall the spout-opening q is formed. The shell of
A

page_text: the converter-chamber may be formed of metal lined with refractory material, as
indicated, the refractory lining, which it is preferred to form of fire-clay, affording
both a heat and an electric insulator. For convenience of access to the interior of
the chamber A, as for repairing linings, renewing the carbon slabs hereinafter
described, and the like, the wall-sections and should be removable and fastened
together and to the respectively adjacent parts of the shell by bolts and keys, or
other means that will permit expeditious separation of the removable wall-sections.
The terma "base" and "top," above employed are applied to the relative parts
of the converter-chamber in the position in which it is shown in Figure 5, being
its initial position, or that in which it receives the charge.
The inner construction of the chamber A forms therein the three compart-
ments p, p¹ and p³, the first-named being the slag-receiving compartment, the
second the mixing compartment, and the third the electric-treatment compartment.
The compartment. contains electrodes o and o¹, preferably in the form of carbon
alabs, which are let into grooves (not shown) in the lining of the compartment,
through the base of which are connected with the respective electrodes the insulated
terminal wires w and w¹ (see Figure 2) leading from the poles of a suitable electric
generator D (say a dynamo-electric machine)..
The converter-chamber A. is supported on hollow trunnions n and n¹ respectively
extending from its opposite sides through bearings at the upper ends of suitable
standards m and m'; and the trunnions carry, near their outer ends, the cog-
wheels and (Figure 1) to be engaged by suitable rack-mechanism (not shown but
such as is commonly used in steel-mills), for tuining the chamber on its trunnions
as hereinafter described.
The base of the mixing compartment p¹ is pierced by feed-tubes h, of refractory
material, (such as fire-clay) each of which contains a pair of diaphragms h', h¹, of
the same material, reaching short of its base to subdivide the tube into a number of
passages for the better distribution of the material which is blown 'through them,
as hereinafter described. These tubes thus form tuyeres.
B and C are pipes, the one leading from a supply (not shown) of gas under
pressure and the other from the same source or from an air-blower (not shown)
through the trunnions n and n¹, in which the pipes are divided, as indicated in
Figure 1, to permit turning, with the converter-chamber, the depending sections
of the pipes, which are connected by branches i with the tuyeres. a removable
box F covers the base of the section to protect the pipes and tuyeres from
injury.
In the horizontal stationary portion of each pipe it is slotted longitudinally, the
slot g (shown in Figure 4) being inclosed by a hopper H rising from the pipe and
containing a rotary fluted cylinder H, journaled in the base-portion of the hopper
to extend lengthwise of and cover the slot g and provided on the outer end of its
stem with a pulley f, through the medium of which to drive the fluted cylinder
and cause it to feed with regularity, into the pipe through its slot, the pulverized
carbonaceous material (coke) E contained in the hopper. The cylinders H¹ so
closely cover the respective slots in the pipes as to prevent escape of gas from 'the
latter.
To start the apparatus, the chamber A. should be preparatorily heated by admitting
gas into it, on opening the valve in the gas-pipe, and igniting the gas, as by 'means
of a handful of burning wood or shavings thrown into the chamber. When the
chamber has been sufficiently heated, the gas is turned off and the chaniber is
brought to the position in which it is shown in Figure 5, in which molten slag is
run into it, through the opening q, either direct from the blast-furnace, or if more
convenient, from a ladle which may be handled through the medium of a hydraulic
lift, such as is ordinarily used in steel-works. The supply of molten slag is thius
introduced into the compartment p. The gas is then slowly turned on and the
coke-feeding mechanism is started and is continued in operation under the 'full
pressure of the gas-supply 'until a sufficient quantity of the carbonaceous material
(say about one part of coke to three parts of slag) has been 'fed, the feetling 'opera-

page_text: tion requiring not more than, say, about five minutes, during which the chamber A
is slowly turned on its trunnions from the position in which it is represented in
Figure 5 to that in which it is represented in Figure 5, and back again. In 'this
manner the molten slag is caused to flow into the mixing-chamber and becomes
thoroughly impregnated throughout its entire mass with innumerable particles of
coke. It may be determined by spectroscopic observation of the carbon-lines of
the converter-flame when the mixing has proceeded far enough.
It should be stated that the only use for an air-blast, hereinbefore referred to, is
when, or if, the supply of gas shall be defective, in which event the air may be
used in conjunction with the pulverized coke for promoting combustion of the
latter to maintain the molten condition of the slag, or to restore any lost heat. The
gas employed may be that evolved from the materials treated in the converter and
should, to enable it to be used, be accumulated and stored in a suitable holder.
On completing the mixing with the slag of the carbonaceous material, (when the
proportions will be about three parts of slag to one part of the carbon) the electric
current is turned on, the gas pressure is turned off, and the converter-chamber is
swung to the position in which it is represented in Figure 5³, whereby the material
is run into the compartment pª.
Blast-furnace slag is a material highly resistant to electricity, being composed
(according to the average sample produced in the manufacture of Bessemer iron) of
about 50 to 55 per cent. of lime; 25 to 28 per cent. of silica; 16 to 18 per cent. of
alumina, and a small proportion of other elements varying in kind according to
the ore reduced in the furnace and the limestone employed as a flux. By mixing
with the slag the carbonaceous material, which is a good conductor of electricity,
and interposing in the circuit the mass of the mixture the latter is rendered con-
ductive but presents to the passage of the current the resistant property of the slag
between adjacent particles of the coke contained therein, whereby innumerable arcs
are formed throughout the mass for generating the great intensity of heat requisite
for the conversion of the mixture into my new or improved product. This product
being reduced slag, forms the carbide of calcium, aluminum and silicon. Thus
the medium (carbonaceous material) of conversion also affords the medium for the
transmission of the current through the mass to be converted to generate the
The coke deoxidizes and
necessary intensity of heat to effect the conversion.
carburets the slag, the reduction requiring no more than about 'twenty minutes
until the slag is thoroughly carburetted, when the current is turned off and the
chamber A is swung to the position in which it is represented in Figure 5° to
discharge the molten product, which may be cast into ingots or in molds of any
desired size and shape. The converter is then ready to be used over again, by,
returning it to its initial position, in which it is represented in Figure 5 to receive
another charge of molten slag.
As an incident of my invention may be mentioned the fact that by enabling the
slag to be conveniently disposed of, without first requiring it to be handled in
running it to a "cinder-bank," in addition to reducing it to a valuable by-product,
the cost of making iron and steel is greatly reduced.
While special apparatus has herein shown and described especial apparatus
for the practice of my process in a particular way, it is not intended thereby that
this invention shall be limited thereto, as the treatment of the slag, to effect the
mixture therewith of the carbonaceous material, may be produced by forcing the
carbon into the molten slag while the latter is running, as from the blast-furnace
to a similar receiver, in which or also while running, the mixture may be subjected
to the electrical treatment. Moreover, the slag may be treated, after it has been
allowed to solidify by cooling, by melting it preparatorily.
Having now particularly described and ascertained the nature of this inven-
tion, as communicated to me by my foreign correspondent and in what manner the
same is to be performed, I declare that what I claim is:-
1. The process of utilizing the waste-product of a blast-furnace, which consists in

page_text: mixing with slag, either in a solidified and divided or in a molten condition, a
suitable proportion of carbonaceous material in a state of suitably fine division and
subjecting the mixture to the action of an electric current by including it in the
circuit thereof.
2. The process of utilizing the waste-product of a blast-furnace, which consists in
mixing with slag, either in a solidified and divided or in a molten condition, a
suitable proportion of carbonaceous material in a state of suitably fine division,
subjecting the mixture to the action of an electric current by including it in the
circuit thereof and injecting a reducing gas into the molten mixture.
3. The process of utilizing the waste-product of a blast-furnace, which consists
in mixing with molten slag a suitable proportion of pulverized carbonaceous
material by blowing said carbonaceous material into the molten mass with a reduc-
ing gas under pressure and subjecting the mixture to the action of an electric
current by including it in the circuit thereof.
4. As a new article of manufacture, the product of the herein described treatment
of blast-furnace slag..
5. In an apparatus for converting blast-furnace slag, a rotatably supported con-
verter-chamber having an opening and subdivided into intercommunicating mixing
and electric-treatment compartments, substantially as and for the purpose set
forth.
6. In an apparatus for converting blast-furnace slag, a rotatably supported con-
verter-chamber having an opening and subdivided into intercommunicating slag-
receiving, mixing and electric-treatment compartiments, substantially as described.
7. In an apparatus for converting blast-furnace slag, the combination of a
rotatably supported converter-chamber having an opening and provided with
tuyeres, a blast-pipe leading to said tuyeres, and provided with an opening, a
hopper seated over said opening and a fluted cylinder rotatably supported on the
hopper and covering said opening, substantially as described.
8. In an apparatus for converting blast-furnace slag, the combination of a con-
verter-chamber A supported on trunnions and provided with an opening q, and
subdivided into intercommunicating compartments 2 and p³, electrodes o and o
in the compartment p³, tuyeres leading into the compartment p', a divided blast-
pipe leading through a trunnion to said tuyeres, and provided with an opening g, a
hopper H seated over the opening in said pipe and a fluted cylinder H¹ rotatably
supported in the hopper and covering said opening, substantially as described.
Dated this 4th day of January 1898.