Improvements relating to the Smelting and Converting of Metal Ores, and to Apparatus therefor.
Year: 1898

page_text: Date of Application, 18th Jan., 1898-Accepted, 19th Mar., 1898
Improvements relating to the Smelting and Converting of Metal
Ores, and to Apparatus therefor.
I, OLIVER STEPHENS GARRETSON, of 972, Main Street, Buffalo, in the County of
Erie, in the State of New York, United States of America, Manufacturer, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement :-
This invention has reference to that class of metallurgical processes and apparatus
which are employed in matte and pyritic smelting for producing a molten matte and
converting or bessemerizing the same.
One object of this invention is to treat the ore in a furnace, or in adjacent
compartments of a furnace, in such manner that metal or enriched matte, as the case
may be, and practically clean slag are produced by a simple and continuous operation.
For this purpose the ore is smelted to a matte in one part or compartment of
the furnace and converted or bessemerized in an adjacent part or compartment of the
furnace, the matte flowing from the matte forming part or compartment, to the con-
verting or bessemerizing part or compartment and the slag flowing from the
converting or bessemerizing part or compartment to the matte forming part or
compartiment where the values contained in the slag are abstracted from the same
before it is allowed to escape.
Another object of this invention is to improve the converting or bessemerizing
process. This process is now generally carried on in a converting vessel provided with
a silicious lining which furnishes the silica for the combination with the iron oxide
produced by the action of the blast upon the iron contained in the matte. This
lining is eaten away to a certain extent by each charge of matte and when the lining
has become too thin for further use the converting vessel is relined.
This process 18
intermittent in its operation and the relining of the converting vessels consumes
much time and labor. According to this invention the matte is converted or
bessemerized by a continuous process in which the matte is supplied to the converting
chamber or compartment continuously, or nearly so, and couverted underneath a
column of flux or silicious material, which latter is supplied from time to time at the
top of the column as may be necessary to replace the silicious material which has
been consumed at the bottom of the column.
In the accompanying drawings consisting of three sheets
Figure 1 is a longitudinal vertical section of a simple form of furnace by which
this improved process can be practiced.
Figure 2 is a horizontal cross section on the line 2-2, Figure 1.
Figure 3 is a vertical cross section on the line 3-3 Figure 2.
Figure 4 is a fragmentary vertical cross section through one pair of the bessemer-
izing tuyeres on the line 4-4, Figure 1.
Figure 5 is a longitudinal vertical section of another form of furnace by which
this improved process can be practiced and which embodies a matte forming furnace,
a converting or bessemerizing furnace or compartment and a forehearth from which
the slag is drawn off.

page_text: Figure 6 is a horizontal section on the line 6-6, Figure 5.
Figure 7 is a vertical section of a separate converting or bessemerizing furnace,
and
Figure 8 is a horizontal section on line 8-8, Figure 7.
Like letters of reference refer to similar parts in the several figures.
Referring to Figures 1, 2, 3 and 4, A represents the matte forming hearth and
B the converting or bessemerizing hearth, arranged side by side and separated by a
dam a of such height that it allows the matte to flow from the matte forming
hearth A to the converting or bessemerizing hearth B, as indicated by the arrow 1,
in Figure 1. b represents the slag outlets or spouts which are arranged over the
matte forming hearth and preferably at that end thereof which is furthest removed
from the converting hearth. c represents a tap hole formed in the matte forming
hearth A for drawing off any metal or rich matte which has accumulated on the same.
d represents one or more tap holes formed in the converting hearth B for drawing off
the metal or converted or bessemerized matte from time to time. E represents the
stack of the furnace which extends over both hearths or compartments A and B and
is provided at its top with suitable contrivances for feeding the ore and flux to the
furnace and for permitting the escape of the gases. For instance, as shown in
Figures 1 and 3, the top of the stack is provided with several inlets for the ore and
flux, arranged side by side and separated by partitions F between which are arranged
inclined doors f. These inlets open at their rear sides into the uptakes G through
which the gases escape. The stack, the partitions, F and the doors fare preferably
water-jacketed as shown.
H represents the smelting tuyeres which are arranged in the stack at such a height
above the hearth as to deliver the blast into the smelting zone of the furnace, which
zone lies somewhat higher than the slag level. The blast is supplied to these tuyeres
from two horizontal blast conduits or trunks h which are arranged along the longi-
tudinal sides of the furnace and receive the blast from any suitable blowing and
heating apparatus.
I represents the converting or bessemerizing tuyeres which are arranged over the
converting or bessemerizing hearth B and at such a height that they deliver the blast
into the layer of molten matte and below the slag level. These converting tuyeres
are supplied with a blast from a separate blowing apparatus of any suitable construc-
tion which supplies a blast under a higher pressure than that of the smelting blast
in order to enable the blast to penetrate the molten matte. The pressure of the con-
verting blast may range from 4 to 5 or more pounds per square inch, while that of
the smelting blast may range from to 1 and ½ pounds. The converting blast may
or may not be beated. Some of these converting tuyeres may be arranged over that
part of the matte forming hearth A which is adjacent to the converting hearth B, as
shown in Figure 1, in order to effect a preliminary conversion of the matte as it
approaches the converting hearth.
In smelting ore according to this invention in this furnace the iron or copper
sulphide ore mixed with a suitable flux, consisting mainly of silica, for instance quartz,
diorite or the like, is charged into the furnace in such manner that the stack is kept
fairly filled with ore and flux. In starting the furnace a suitable amount of fuel
is used but when the operation 1S fully established the fuel may
be entirely omitted, or nearly so, in accordance with the percentage of com-
bustible ingredients contained in the ore. As the ore is being smelted down a matte
is formed which collects on the hearths A and B. That part of the matte which
collects on the converting hearth B is converted or bessemerized, either so that the
metal is precipitated or so that an enriched matte accumulates on this hearth. The
iron oxide which is formed or liberated in forming the matte and in converting or
bessemerizing the same combines with the silica to a silicate which is a freely flowing
slag. The slag so formed over the converting hearth flows in the direction of the
arrow 2, Figure 1, from the converting hearth to the matte forming hearth and thence
to the slag outlets 6 where it is drawn off, either continuously or from time to time
as may be most convenient. The slag is so compelled to flow slowly through the

page_text: matte forming region of the furnace where the ore and poor matte predominate. The
sulphur which is present in excess in this region combines readily with any free
metals or oxides which may be carried by the slag and converts such metals into
matte, whereby the copper and other values carried by the slag are intercepted and
returned to the matte. The latter flows on the matte forming hearth toward the
converting hearth and over the dam a to the latter and is there again subjected to
the converting and bessemerizing blast.
In this manner a constant circulation is maintained in the molten material in the
furnace. A molten sulphur compound or matte is constantly formed in the portion
of the furnace furthest from the converting hearth. This comparatively poor matte
flows constantly along the matte forming hearth toward the converting hearth and
becomes gradually richer by the burning out of the sulphur, iron and other
combustible ingredients, the rich matte is constantly converted or bessemerized in
that portion of the furnace into which the converting blast is delivered, a corre-
spondingly rich slag is constantly formed in that portion of the furnace and this slag
flows in the opposite direction or from the converting portion or compartiment and
passes through the matte forming portion of the furnace before it is allowed to escape
so that the values contained in this slag are exposed to the action of the predominating
sulphur and poor matte in the matte forming portion of the furnace and are there
intercepted and returned, whereby the escape of values with the slag is to a large
extent prevented.
In order to promote this action the matte forming portion or compartment of the
furnace is preferably charged with proportionately more ore and less flux and the
converting or bessemerizing portion or compartment with proportionately less ore and
more flux, so that the raw ore and poor matte predominate in the matte forming
portion and the flux in the converting or bessemerizing portion. If the ores differ in
the percentage of sulphur or other combustible ingredients the ore containing most
sulphur is used in the matte forming portion.
The metal or rich matte which accumulates on the hearth is drawn off from time.
to time through the tap holes.
Referring to Figures 5 and 6, K represents the stack of the main or smelting furnace
and the hearth thereof. L represents the stack of the converting or bessemerizing
furnace or compartiment and the hearth thereof. This converting furnace or
compartment is arranged on one side or end of the main furnace and connected
therewith above the hearth by a passage M in which is arranged a dam m of such
height as to permit the matte to flow from the hearth of the smelting furnace to
the hearth of the converting furnace, while the slag flows through the passage M in
the opposite direction.
.
N represents a forehearth or settling well which is arranged at the opposite end of
the furnace and communicates therewith by a passage (. A dam n is arranged in
this passage and made of such height that it prevents the matte from flowing through
this passage while it permits the slag to flow over and upon the hearth n¹ of the
forehearth. This forehearth is provided with a slag spout p through which the slag
escapes and the bessemerizing furnace N may also be provided with a slag spout pl.
Q represents the smelting tuyeres arranged mainly in the smelting furnace K and q
the bessemerizing or converting tuyeres arranged mainly in the bessemerizing or
converting furnace L.
In operating this furnace a matte is formed in the smelting furnace K by smelting
the ore, this matte is converted or bessemerized in the converting furnace L, and the
slag formed in the latter flows back and passes through the smelting furnace on its
way to the slag outlet whereby the slag is exposed to the action of the ore, poor
matte and sulphur in the smelting furnace and the values contained in the slag are
extracted. The stack of the converting furnace is kept supplied with a column of
flux in lumps, such as quartz, diorite, or other mineral containing a large percentage
of silica. The weight of this column keeps the lower portion of the column pressed
downinto the layer of matte, so that the iron oxide which is heing formed in the matte
by the oxidizing blast can act upon the silica and combine with the same to a silicate

page_text: which forms a liquid slag. The latter rises to the surface of the molten material and
flows back into the main furnace and joins the slag produced in the same. The
circulation of the molten material is the same as that which takes place in the
furnace represented in Figures 1 to 4 and the deposited metal or rich matte is
drawn off from time to time through the tap holes arranged in the hearth.
In some cases it is not desirable to carry the process of conversion so far that metal
is actually precipitated but only far enough to concentrate or enrich the matte
preparatory to further treatment. This depends largely upon the nature of the ores
and upon other conditions and is readily accomplished by regulating the converting
operation accordingly.
If necessary the forehearth N may be kept filled with a column of charcoal through
which the slag is filtered before escaping and whereby further values contained in the
slag are filtered out or reduced. The forehearth may also be provided with tuyeres Q
for supplying air to burn a sufficient part of the charcoal to keep the slag in a fluid
state.
This improved converting or bessemerizing method can also be practised without
returning the slag to the smelting furnace. Figures 7 and 8 represent a converting
or bessemerizing furnace which is constructed in all material respects like the above
described converting furnace or compartment L but which is not directly connected
with a smelting furnace. This converting furnace is supplied with molten matte
through a spout r, either continually or from time to time as may be most convenient,
and the liquid slag is discharged through a spout 8, either continually or from time to
time. This furnace is kept charged with a column of silicious material, as hereinbefore
described which material is supplied through a door t in the upper portion of the
furnace and the gases escape through a pipe T. The slag discharged from this
furnace must be treated separately if it is sufficiently rich to warrant such treatment.
If necessary a small amount of carbonaceous fuel may be supplied to the furnace with
the flux. If desired the matte may be supplied to this furnace from the top in
lumps or pigs instead of in a molten condition.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. The herein described method of matte or pyritic smelting which consists in
conducting the operations of producing molten matte and converting or bessemerizing
the same side by side in the same furnace or in adjacent compartments or furnaces,
maintaining a flow of matte from the matte forming region, compartment or
furnace to the converting or bessemerizing region, compartment or furnace, forming
a fluid slag by the addition of flux in the converting or bessemerizing region,
compartment or furnace, and compelling such slag to flow through the matte formning
region, compartment or furnace on its way to the slag outlet, thereby subjecting the
slag to the action of the sulphur and sulphide in the matte forming region,
compartment or furnace, whereby the values contained in the slag are intercepted
and returned to the matte.
2. The hereindescribed method of converting or bessemerizing molten matte which
consists in subjecting the matte to a converting or bessemerizing blast underneath a
column of flux or silicious material.
3. The herein described method of matte or pyritic smelting which consists in
conducting the operation of producing molten matte and converting or bessemerizing
the same in the presence of a column of flux or silicious material side by side in the
same furnace or in adjacent compartments or furnaces, and maintaining a flow of
matte from the matte forming region, compartment or furnace to the converting or
bessemerizing region, compartment or furnace.
4. A combined smelting and converting furnace having a smelting or matte
forming hearth and a converting or bessemerizing hearth arranged side by side, a
stack arranged over said hearths, tuyeres whereby a smelting blast is delivered over

page_text: the smelting hearth, and converting or bessemerizing tuyeres arranged over the
converting or bessemerizing hearth.
5. A combined smelting and converting furnace composed of a smelting furnace
having a stack to receive the ore and flux and a converting or bessemerizing furnace
having a stack for the reception of a column of flux or silicious material and
communicating with the smelting furnace by a passage through which the matte
flows from the smelting furnace to the converting furnace.
6. A combined smelting and converting furnace composed of a smelting furnace
having a stack to receive the ore and flux, a converting or bessemerizing furnace
arranged on one side of the smelting furnace and having a stack for the reception of
a column of flux or silicious material and communicating with the smelting furnace
by a passage through which the matte flows from the smelting furnace to the
converting furnace, and a forehearth arranged on the other side of the smelting
furnace and communicating with the same by a passage through which the slag flows
from the smelting furnace to the forehearth.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.