Specialized metallurgical processes – compositions for use therei – Processes – Consolidating metalliferous material by agglomerating,...
Reexamination Certificate
1999-08-31
2001-11-06
Kastler, Scott (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Processes
Consolidating metalliferous material by agglomerating,...
C075S746000
Reexamination Certificate
active
06312501
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of producing reduced iron and production facilities therefor, and particularly relates to production facilities for annexing a rotary bed-type direct reducing furnace with a sealed-type electro-blast furnace, a pellet production facility including the rotary bed-type direct reducing furnace and a few improved methods of producing pellets containing reducing materials, and a production facility and method for supplying the pellets into a rotary bed-type direct reducing furnace, and further relates to compositions of raw materials and binders for producing pellets.
2. Background Art
Conventionally, reducing iron is obtained by the steps of forming pellets using mixed raw materials of iron ore and a carbonaceous material by means of pellet production facilities, and by reducing the pellets by means of a direct reducing furnace.
The reduced iron pellets are obtained by forming raw material pellets which are a mixture of raw materials such as an oxide particulate of iron ore and a particulate of carbonaceous material like coal and by heating these pellets at high temperature in a rotary bed-type direct reducing furnace. The thus produced reduced iron pellets are then placed into a melting furnace for meting the reduced pellets and for producing pig iron. Conventionally, a sealed type blast furnace, a so-called submerged arc-furnace is used as the melting furnace, and will be described later.
Production of reduced iron by the rotary bed-type furnace is advantageous in many respects such as (1) it is possible to utilize coal with a reduced cost as the reducing agent, (2) it is possible to acquire a favorable heat economy, since preheating of the raw material pellets prepared by raw materials is not necessary, (3) the reduction reaction can be completed within a short time (approximately 10 min.), because the materials to be reacted (the iron ore powder and the carbonaceous material powder) are in close contact with each other. Therefore, it is possible to construct the rotary bed-type direct reducing furnace in a simple structure and at a reduced cost.
Hereinafter, a conventional rotary bed-type direct reducing furnace will be explained in detail with reference to
FIGS. 15 and 16
.
FIG. 15
is a perspective view of the conventional rotary bed-type direct reducing furnace (hereinafter, referred to as a reducing furnace). The reference numeral
101
is the reducing furnace,
122
is a burner provided through the side wall of the reducing furnace,
113
is a transporting device for charging the pellets into the reducing furnace,
102
is a conveyer such as a reciprocating conveyer for charging the pellets in a uniformly layer on the rotary bed,
124
is a pellet discharging device such as a screw-type discharging device for discharging reduced pellets (reduced iron pellets) from the reducing furnace,
104
is a container for temporary storing the reduced iron pellets, and
105
is an exhaust gas duct for discharging the combustion gas in the reducing furnace.
The raw material pellets produced by mixing the iron ore powder as the oxide material and a coal powder as the carbonaceous material is supplied to the reciprocating conveyer
102
through the transporting device
113
. The raw material pellets are charged into the reducing furnace
101
uniformly as one or two layers on the rotary bed
127
. This pellet filled layer is heated by the burner
122
at about 1200° C. and reduced during turning one round in the direction shown by an arrow (clockwise revolution in
FIG. 15
) in the reducing furnace
101
, and the reduced pellets are discharged by the screw type discharging device
124
from the reducing furnace
101
, and stored in the container
4
. The combustion gas in the reducing furnace
101
, after heating the raw material pellets, is discharged through the exhaust dust
105
to the outside the reducing furnace
101
, and released into the atmosphere.
FIG. 16
is a cross-sectional developed diagram along the center of the reducing furnace clockwise showing the pellet charging portion and the reduced pellet discharging portion. In
FIG. 16
, the reference numeral
103
denotes a reduced iron pellets discharging chamber (discharging portion) for discharging the reduced iron pellet layer
128
. The rotary bed
127
of the reducing furnace
101
is made of a refractory, its bottom is constructed by a steel member, and wheels are annexed under the steel member. The reference numeral
131
is a rail for these wheels. The rotary bed
127
of the rotary bed-type reducing furnace
101
rotates such that it moves from left to right in a cross-sectional and developed diagram along the center axis of the reducing furnace. The burner
122
is used for heating the raw material pellets and air for combustion is supplied to the burner through an air line
123
. The reference numeral
134
is a combustion flame, and
125
is a cooling device for cooling the pellet layer indirectly in order to prevent the reduced iron pellet layer from burning. The reference numeral
126
is a damper for sealing the gas flow between the reduced iron pellet discharge chamber and the raw material pellet charging chamber
102
.
As hereinabove described, a conventional facility for producing the reduced iron pellets having high mechanical strength is described in detail. Although the reduced iron pellets are produced by the above-described rotary bed-type direct reducing furnace, the other systems may be used for producing reduced iron which comprises a few annexed equipment.
FIG. 17
illustrates a facility containing a perspective view of the rotary bed-type direct reducing furnace
201
, wherein the raw material pellets are supplied onto the rotary bed
206
by a charging conveyer
202
through a charging conveyer
204
. The inside (chamber of the rotary bed-type direct reducing furnace
210
is heated by use of a plurality of burners (not shown).
As shown in
FIG. 17
, a reduced iron pellet production facility comprises a conventional rotary bed-type direct reducing furnace
201
, shown as a cross sectional developed diagram, for producing the reduced iron pellets by heating the raw material pellets P
1
at high temperatures, and a rotary cylinder-type cooler
202
for cooling the reduced iron pellets P
2
preserved at high temperature after receiving them at a transfer portion
208
during rolling.
The reference numeral
203
denotes a pelletizer for producing pellets of the mixture of the raw materials comprising an iron ore powder and a coal powder. The reference numeral
204
denotes a transporting device such as a belt conveyer,
205
denotes a pellet charging device for charging pellets on the bed
206
into a uniform pellet layer
207
.
The reference numeral
208
denotes a discharging device for discharging the heated reduced iron pellets P
2
into the rotary cylinder-type cooler
202
, and
209
denotes an exhaust gas duct for discharging the combustion gas.
The reference numeral
210
shown in
FIG. 4
denotes a cylindrical chute for delivering the reduced iron pellets P
2
heated at a temperature of 1100° C. into the rotary cylinder-type cooler
202
and
211
denotes a gas sealing hood.
The reference numeral
212
denotes spray nozzles for spraying cooling water on the outside surface of the rotary cylinder-type cooler
202
, and
213
denotes a spray nozzle for spraying cooling water directly on the reduced iron pellets located near the exit port of the cooling cylinder
102
. The reference numerals
214
and
215
denote rubber-rollers for supporting the rotating rotary-cylinder-type cooler
202
, and
216
denotes a gear for driving the rotary cylinder-type cooler. The numeral
217
denotes a hood as well as a hopper,
218
denotes a sieving screen, and
219
denotes an exhaust duct of water vapor.
Conventionally, although the same rotary base-type reducing furnace as shown in
FIG. 15
is used, another method for producing reduced iron pellets is known, in which, wet raw material pellets formed by addin
Fujioka Hironori
Hirata Koichi
Itano Shigeo
Kamikawa Susumu
Kawamoto Tetsumasa
Kastler Scott
Mitsubishi Heavy Industries Ltd.
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