Methods for melting and refining a powdery ore containing metal oxides

A powdery or fine granular ore containing metal oxides is melted and refined by charging the ore and a part of a reducing gas discharged from a vertical type of melting and reducing furnace into a fluidized bed type of preliminary reducing furnace to preliminary reduce the ore therein, charging the preliminary reduced ore heated at a high temperature into the above described melting and reducing furnace and melting and reducing the ore by using a carbonaceous solid reducing agent and air or oxygen rich air heated at a high temperature and discharging the molten metal and the molten slag from the melting and reducing furnace. By using the preliminary reduction step, the pretreatment of the powdery or fine granular ore containing metal oxides, such as formation into pellets, sintered ores, briquets and the like can be omitted.

BACKGROUND OF THE INVENTION 
The present invention relates to methods for melting and refining a powdery 
or fine granular ore containing metal oxides by preliminarily reducing the 
ore and then melting and reducing the preliminarily reduced ore and 
apparatuses for melt-refining the ore and particularly to methods for 
melting and refining the ore by preliminarily reducing the ore by means of 
a reducing gas generated upon the melting and reducing the ore and then 
melting and reducing (referred to as "melt-reducing" hereinafter) the 
preliminarily reduced ore and apparatuses for melt-refining the ore. 
There has been a long-felt need to develop novel methods for refining an 
iron ore or a metal oxide ore. Various methods have been tried and 
practically carried out. However, most of them had severe drawbacks. 
Concerning the form of ores containing iron oxide or various metal oxides, 
there is a tendency that the lump ore is reduced and the powdery ore is 
increased. In particular, in order to improve the quality of low grade 
ores, mineral processings, such as magnetic separation, floatation and the 
like have been carried out and it is expected that the ratio of powdery 
ores is more increased in future. A major part of the presently operating 
refining furnaces needs lump ores or previously treated lump ores and 
powdery ores are formed into pellets, sintered ores, briquets, and the 
like. Such a formation needs superfluous materials, such as solvents, 
binders, etc., fuels and motive powers. When a firing furnace is used for 
such a formation during the hot step, NOx, SOx and dusts are generally 
formed and if these substances are directly discharged, a problem of 
environmental pollution occurs, so that installations for preventing the 
environmental pollution are built but this needs a large cost. 
As a technique capable of directly using powdery ore, a roasting or a 
reducing process using a fluidized bed is partially practically used. 
However, when the preliminarily reduced powdery ore is used in an electric 
furnace, a converter and other melting furnaces, in most case, a binder is 
added thereto and the mixture is formed into briquets and the like. It has 
been proposed that the powdery ore be used in a process utilizing an arc 
furnace or plasma but the amount of electric power consumed in such 
process is very large and in countries where the electric power cost is 
high (as in Japan), this process would not be cost effective or 
competitive enough. 
As a means for supplying the heat energy necessary for the reduction and 
heating, there is a means utilizing combustion heat wherein coke is burnt 
by using mainly air without using electric power or pure oxygen and a 
blast furnace for refining iron, nickel, copper, etc. uses this process. 
In particular, it has been well known that the iron making blast furnace 
is very high in efficiency as a refining furnace due to operative 
technical progress and by enlarging the size of furnace. But the iron 
making blast furnace is a high shaft furnace and in order to ensure the 
air permeability in the furnace, the above described lump ores or the lump 
formed ores are necessary and further the lump ores and coke are piled in 
layer-form in the furnace, so that coke having a high strength is needed. 
For the production of the coke having a high strength, a high caking coal 
having a high price, which presumably becomes insufficient in the future 
in view of the resources as the starting coal is necessary or when a low 
caking coal or a usual coal is used, an improving binder is necessary and 
the production cost is increased. 
It has been proposed in Japanese patent application publication No. 
2,103/59 or Japanese patent laid-open application No. 142,313/79 that the 
powdery preliminarily reduced ore prepared by preliminarily reducing 
powdery ore is melted and reduced in the powdery state and in the former 
process, a burning assistant for burning a fuel is a gas containing more 
than 85% of oxygen and in the latter process, the assistant is pure 
oxygen. In order to maintain the molten metal pool in the melt-reducing 
furnace at a high temperature, in the former process, a gas having 
CO.sub.2 /CO ratio of 1 which has an oxidizing function against Fe is 
evolved through a reaction of coal with oxygen, and in the latter process, 
carbon attached to the preliminarily reduced ore is burnt with pure 
oxygen. Furthermore, in the former process, the gas is oxidizing, so that 
iron oxide is apt to be formed into slag in unreduced state and discharged 
out of the furnace, and in the latter process, the unevenness of the 
temperature in the combustion furnace and the unevenness of the oxygen 
partial pressure are apt to be caused, so that the settlement of the 
operating condition in the melting furnace is difficult. 
SUMMARY OF THE INVENTION 
The present invention aims to provide an improved production method wherein 
various drawbacks, encounted in the previously proposed methods for 
producing a molten metal from a powdery ore containing metal oxides, are 
obviated. 
The present invention lies in methods for melting and reducing a powdery 
ore containing metal oxides including preliminarily reducing a powdery or 
fine granular ore containing metal oxides in a fluidized bed type of 
preliminary reducing furnace by feeding a part of a reducing gas 
discharged from a vertical type of a melting and reducing furnace into the 
preliminary reducing furnace, charging the preliminarily reduced ore into 
the above described melting and reducing furnace (referred to as 
"melt-reducing furnace" hereinafter) at a high temperature and melting and 
reducing the ore by using a carbonaceous solid reducing agent and air or 
oxygen rich air heated at a high temperature to melt and reduce the ore 
and discharging the molten metal and the molten slag from the 
melt-reducing furnace.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A first aspect of the present invention will be explained in detail 
hereinafter. 
According to the present invention, a packed bed composed of a carbonaceous 
solid reducing agent is provided in the melt-reducing furnace, a preheated 
air or a preheated air added with oxygen is blown to the packed bed from 
tuyeres and in this case a preliminarily reduced powdery or fine granular 
ore and a flux or a mixture of powdery or fine granular ore and powdery 
flux which has been subjected to preliminary reduction are concurrently 
carried on the gas flow and blown into the furnace from the tuyeres, the 
charged mixture is melted at highly heated zones caused at the 
circumference of the tuyere top end portions and the molten ore is reduced 
when the molten ore is dropped down through the above described packed bed 
and the molten metal is collected together with the molten slag in a 
bottom floor of the melt-reducing furnace and timely discharged out of the 
furnace. The above described preliminarily reduced ore is obtained by 
preliminary reduction using a reducing gas discharged from the 
melt-reducing furnace. The above described flux serves to develop the 
function of a melt-promoting agent or a desulfurizing agent upon the 
melt-reduction and as the flux, use may be made of limestone, silica, 
dolomite, surpentine, etc. according to the property of the ore. 
An embodiment carrying out the present invention will be explained with 
reference to FIG. 1. 
Powdery or fine granular metal oxide is fed from a feeder 1 to a 
preliminary reducing furnace 2. A part or the whole of a gas heated at a 
high temperature, which is discharged from a vertical melt-reducing 
furnace 3 through a gas outlet 4 is introduced into the preliminary 
reducing furnace 2 through a gas inlet 5 in the preliminary reducing 
furnace 2 and dries, heats and preliminarily reduces the metal oxide 
charged in the preliminary reducing furnace by a fluidized system. Thus 
preliminarily reduced ore is discharged from an outlet 6 and blown into a 
vertical furnace 3 together with preheated air through a pipe 7 shown by a 
dotted line and tuyeres 8 and/or 8'. In this case, in order to make the 
transfer of the preliminarily reduced ore in the pipe 7 easy, it is 
advantageous to use a part of the gas discharged from the vertical furnace 
3 after the pressure of the gas is raised by means of a pressurizing 
device 9, as a carrier gas. The heated air (referred to as "hot air" 
hereinafter) blown into the vertical furnace 3 is heated to 
800.degree.-1,300.degree. C. in a gas heating furnace 10. Oxygen gas may 
be blown together with the hot air. Furthermore, a flux may be blown 
together with the preliminarily reduced ore into the vertical furnace 3 
through the tuyere by the hot air in order to advantageously effect the 
melt-reducing refining. 
Into the vertical furnace 3 is fed a reducing agent through a feeding 
device 11 of a carbonaceous solid reducing agent and a reducing agent 
packed bed is formed in the furnace 3 and raceways are formed owing to the 
hot air in the vicinity of the tuyere tops in the furnace 3 in the same 
manner as in the vicinity of the tuyere top of a blast furnace and high 
temperature zones at 2,000.degree.-2,500.degree. C. are formed and the 
preliminarily reduced ore blown together with the hot air or oxygen to be 
added into these zones is immediately heated and easily melted. The melted 
ore is reduced during dropping down in a lower portion of the furnace 3 to 
form a molten metal and a molten slag and to effect the refining and the 
refined metal is collected in the furnace bottom portion and timely 
discharged out of the furnace from a taphole 12. 
The circumference of the above described raceway portions forming the high 
temperature zone is the packed bed consisting of lump carbonaceous 
reducing agent and the gas at the circumference of the raceway portions is 
low in the oxygen content, that is the oxygen partial pressure is low, so 
that the reduction of the preliminarily reduced ore which is melted at the 
raceway portions in the furnace 3 is very preferably carried out. 
In the present invention, as the carbonaceous solid reducing agent, use may 
be made of lump coke, lump char or coal alone or in admixture. The height 
of the vertical furnace 3 may be made lower than that of a usual blast 
furnace and the preliminarily reduced ore is supplied into the furnace 3 
from the tuyeres, so that the reducing agent having high strength as in a 
blast furnace is not needed and therefore expensive caking coal is not 
needed and this is commercially advantageous. 
In the present invention, the preliminarily reduced ore is once oxidized by 
oxygen in the hot air in the raceway portions and heated and melted due to 
the reaction heat, so that the reduction ratio is high and the use of the 
preliminarily reduced ore at a high temperature renders the melting easy 
and the present invention is advantageous in this point. The preliminary 
reduction ratio is varied depending upon the kind of ore and the like but 
the best results can be obtained within the range of 40-80%. 
According to the present invention, in order that the preheated and 
preliminarily reduced ore blown into the furnace together with the hot air 
through the tuyere is melted and reduced near the tuyere top, a large heat 
energy is necessary and even if the ore is melted in the vicinity of the 
tuyere top, when the heat supplement at the lower portion of the furnace 
is insufficient, the reduction of the molten ore is not satisfactorily 
caused and the operation becomes impossible due to cooling down of the 
furnace floor, so that in order to prevent this cooling down, the tuyeres 
must be provided at the upper and lower two stages. In this case, the 
preliminarily reduced ore is mainly fed from a tuyere 8 positioned at the 
upper stage and melted in the vicinity of the tuyere top in the upper 
stage and the lower portion of the furnace is heated to a high temperature 
by the tuyere 8' in the lower stage and the heat energy necessary for 
reducing the molten ore dropped down from the vicinity of the tuyere top 8 
in the upper stage is supplied. 
This invention will be explained with reference to FIG. 2. 
A powdery carbonaceous reducing agent is fed into the preliminary treating 
furnace 32 from a device 31 for feeding the carbonaceous solid reducing 
agent and a part or the whole of gas generated in a vertical reducing 
furnace 33 is introduced into the preliminary treating furnace 32 through 
an outlet 34 and a pipe 35 and the reducing agent is dried and heated 
while being fluidized in the preliminary treating furnace 32 to effect the 
preliminary treatment by which the reducing agent is heated or carbonized 
to a necessary extent. For example, when powdery coal is used, the above 
described coal is subjected to carbonization through the preliminary 
treatment in the preliminary treating furnace 32 to prepare powdery cokes 
or char, which is discharged from the above described furnace 32. 
The powdery carbonaceous reducing agent may be directly fed into the 
vertical reducing furnace 33 without using the preliminary treating 
furnace 32 but when carbonized gas containing hydrocarbons or tar is 
necessary in the preliminary reducing furnace and other installations or 
the above described reducing agent must be preheated in order to make the 
burning of the powdery carbonaceous solid reducing agent in the vertical 
reducing furnace easy, it is particularly advantageous to preliminarily 
treat the reducing agent in the preliminary treating furnace 32. 
On the other hand, powdery ore containing metal oxides is fed into the 
preliminary treating furnace 37 from an ore feeding device 36 and a part 
or the whole of gas generated from the vertical reducing furnace 33 and/or 
a part or the whole of the gas generated from the preliminary treating 
furnace 32 are fed into the furnace 37 through pipes 38 and 39 and the 
above described powdery ore is dried and heated while being fluidized in 
the furnace 37 and preliminarily reduced to the desired extent. The gas 
generated from the vertical reducing furnace 33 includes N.sub.2, CO, 
CO.sub.2, H.sub.2, H.sub.2 O and the like and among them, the content of 
the reducing CO and H.sub.2 is high and the gas is discharged at a high 
temperature of 900.degree.-1,500.degree. C. from the vertical furnace 33 
and the gas generated from the preliminary treating furnace 32, when coal 
is the starting material, includes N.sub.2, CO, CO.sub.2, H.sub.2, H.sub.2 
O, CnHm (meaning hydrocarbons) and the like and among them, the content of 
the reducing CO, H.sub.2 or CnHm is high and the gas is discharged at a 
temperature of 300.degree.-800.degree. C. from the outlet 32a of the 
preliminary treating furnace 32. Accordingly, the powdery ore is 
preliminarily reduced while being fluidized in the preliminary reducing 
furnace 37. The preliminarily reduced ore is discharged under a highly 
heated condition from the preliminary reducing furnace 37 by means of a 
discharging device 40 and is transferred to at least one of preliminarily 
reduced ore feeding devices 42, 43 and 44 through a guide device 41 with a 
flux being added on the way if necessary and charged into the vertical 
reducing furnace 33. The preliminarily reduced ore is transferred with gas 
to the feeding devices 43 and 44 and as the carrying gas, use is made of 
the gas generated from the vertical reducing furnace 33 and in some case, 
it is advantageous to pressurize the above described carrying gas by means 
of a pressurizing device 45, because the transfer of the preliminarily 
reduced product with gas is made easy. 
The carbonaceous reducing agent treated in the preliminary treating furnace 
32 is discharged from an outlet 46 and if necessary, pressurized by means 
of a pressurizing device 47a through a guide device 47 and fed into the 
vertical reducing furnace 33 through at least one of feeding devices 48, 
49 and 50 and reacted with an oxygen-containing gas having a high 
temperature, which is supplied from inlets 51 and burnt therein, or 
contacted with metal oxides in the preliminarily reduced ore, which has 
been fed into the vertical reducing furnace 33 and melted therein, whereby 
the metal oxide is reduced to form the metal. 
As the oxygen-containing gas having a high temperature, use may be made of 
air or oxygen rich air which is heated to a temperature of 
800.degree.-1,300.degree. C. by means of a gas heating furnace 52, such as 
a hot air furnace. 
Powdery carbonaceous solid reducing agent or powdery carbonaceous solid 
reducing agent treated in the preliminary treating furnace is burnt with 
the oxygen-containing gas at a high temperature at an upper zone above the 
position of the top of the tuyere-shaped feeding device 50 in the furnace 
33, to evolve a high temperature and therefore the preliminarily reduced 
ore is heated, melted and reduced in the high temperature zone to form a 
molten metal and a molten slag, which are collected in two layers at the 
lower portion of the vertical reducing furnace 33 and the molten metal is 
timely discharged out of the furnace from an outlet 53. 
In the present invention, as carbonaceous solid reducing agent supplied to 
the preliminary treating furnace 32, use may be made of powdery coke, char 
and coal alone or in admixture and when coal is used, inexpensive 
non-caking usual coal can be advantageously used and when lump coke is 
used, powdery cokes prepared in the production of lump cokes can be 
advantageously used. 
It is necessary that the preliminarily reduced powdery ore supplied to the 
vertical reducing furnace 33 is quickly melted and reduced in the high 
temperature zone in the vertical reducing furnace 33, so that it is 
advantageous because the melt-reduction is easily effected, that the 
preliminarily reduced ore, which has been preheated to a high temperature 
and reduced to a high reduction ratio, is fed into the vertical reducing 
furnace 33. The optimum preheating temperature and preliminary reduction 
ratio naturally vary depending upon the kind of metal oxides, the state of 
ore containing metal oxide and the used system construction but when the 
preheating temperature and the preliminary reduction ratio are about 
400.degree.-1,000.degree. C. and 40-80% respectively, the good results can 
be obtained. 
According to the present invention, an oxygen-containing gas having a high 
temperature of 800.degree.-1,300.degree. C. is blown into the vertical 
reducing furnace 33 through a tuyere 51, so that a circumference of an 
inner end of a tuyere-formed feeding device 50 is heated to a temperature 
of 2,000.degree.-2,500.degree. C. The shape of the tuyere 51 may be made 
similar to the shape of tuyere of an iron making blast furnace but in 
order to maintain the temperature of the molten metal pool portion at the 
furnace floor at 1,400.degree.-1,700.degree. C., it is desirable that an 
inclined angle of the tuyere 51 projecting into the furnace is within a 
range to 45.degree. downwardly from the horizontal so that the high 
temperature gas directly contacts with the above described molten metal 
pool portion. 
In order to maintain the vicinity of the inner end of the feeding device 50 
at a high temperature of 2,000.degree.-2,500.degree. C., an excess amount 
of oxygen should be supplied to the vicinity from the tuyere 51 as an 
oxygen-containing gas having a high temperature. However, the high 
temperature is kept thereby and concurrently the oxygen pressure in this 
vicinity is increased and therefore a reoxidation of the molten 
preliminarily reduced ore occurs and a concentration of iron oxide 
contained in the discharged slag increases and this is not desirable in 
view of the reduction. In order to avoid such disadvantage, it is possible 
to maintain the vicinity of the inner top of the feeding device at a high 
temperature and in a reducing atmosphere by directly supplying the powdery 
reducing agent on the molten slag surface from the feeding device 50 
positioning below the tuyere 51 for feeding the oxygen-containing gas 
having a high temperature. 
Then, a detailed explanation will be made with respect to the second aspect 
of the present invention. 
According to the present invention, powdery ore is fed into an upper zone 
which is formed by defining a vertical furnace by a perforated plate into 
the upper and lower zones. A reducing gas formed in the lower zone rises 
into the upper zone through the perforated plate and the powdery ore is 
dried, heated and reduced while being fluidized with this gas to a 
necessary degree. The reducing gas generated in the lower zone may rise in 
a part or the whole into the upper zone through the perforated plate, or 
in a certain case, the reducing gas or an inert gas may be supplied to the 
vicinity below the perforated plate in the lower zone from the outside to 
control the fluidized state of the ore or the temperature, component 
composition and the like of the fluidizing gas in the upper zone. 
The gas generated in the lower zone includes N.sub.2, CO, CO.sub.2, 
H.sub.2, H.sub.2 O, C.sub.m H.sub.n, etc. and among them the content of 
gas having a high reducibility, such as CO, H.sub.2, C.sub.m H.sub.n, etc. 
is high and the temperature is 600.degree.-1,200.degree. C. and this gas 
is introduced into the upper zone through the perforated plate. The ore 
which has been subjected to the fluidizing preliminary reduction in the 
upper zone, is overflowed and discharged at a high temperature from an 
outlet provided in the upper zone from the upper zone and blown into a 
carbonaceous material filled bed formed in the lower zone by adding a flux 
together with air or oxygen rich air heated at a high temperature through 
upper tuyeres provided in the lower zone. The above described air or 
oxygen rich air is heated at a temperature of 800.degree.-1,350.degree. C. 
in a gas heating furnace, such as a hot air furnace. Air or oxygen rich 
air having a high temperature is blown also from the lower tuyeres. At the 
vicinity of the top ends of the upper and lower tuyeres, the carbonaceous 
material forming the packed bed is burnt and a high temperature is 
evolved, so that the above described blown preliminarily reduced ore is 
heated and melted and directly reduced with solid carbonaceous material 
during dropping down in the packed bed to form a molten metal and a molten 
slag, which are collected at the bottom of the lower zone and the molten 
metal is timely discharged out of the vertical furnace. 
As the carbonaceous material, lump coke is mainly used but lump coal, char, 
charcoal, etc. may be used alone or in combination. 
In this invention, the height of the vertical furnace may be rendered lower 
than that of a usual iron making blast furnace and it is not necessary to 
charge lump cokes in layer alternately as in the iron making blast 
furnace, so that cokes having a high strength is not needed, so that 
expensive caking coal is not needed. 
In the present invention, unless the preliminarily reduced ore fed from the 
upper tuyeres is rapidly melted at the vicinity of the tuyeres, the ore 
cannot be dropped down to the bottom portion in the lower zone and this 
causes an operating trouble but this trouble can be prevented by blowing 
air or oxygen rich air having a high temperature from the tuyere in the 
lower zone. The preliminarily reduced ore blown from the tuyeres is once 
oxidized with oxygen and the heating and melting are promoted owing to the 
reaction heat. Accordingly, as the preliminarily reduced ore is higher in 
the reduction ratio and in the preheating temperature, the melting becomes 
more easy. The optimum preliminary reduction ratio is naturally varied 
according to the kind of ore and the system construction but said ratio is 
preferred to be about 40-80%. 
One embodiment for carrying out the present invention will be explained 
with respect to an apparatus shown in FIG. 3. 
A vertical furnace 81 is defined by a perforated plate 83 into an upper 
zone and a lower zone. The upper zone is provided with a feeding device 62 
for a powdery ore and a guide device 58 by which the powdery ore 
preliminarily reduced in the upper zone is overflowed and discharged in 
the fluidized state from the upper zone to the lower zne, and further an 
outlet 60 for the exhaust gas after the fluidizing reduction in a 
relatively upper portion in the upper zone is provided. 
In the lower zone, there are provided a plurality of tuyeres 56 and 54 at 
an upper stage and a lower stage respectively and the tuyeres 56 in the 
upper stage are connected to the above described feeding device 58. At a 
zone just below the perforated plate 83 at a relatively upper portion of 
the lower zone, a device 55 for controlling a reducing gas generated in 
the lower zone may be provided, if necessary. A carbonaceous material 
feeding device 57 to the lower zone is provided and the lower portion of 
this feeding device 57 are branched in the upper zone and form branched 
tubes 59 and these branched tubes 59 penetrate the perforated plate 83 and 
are suspended in the lower zone. An outlet 61 discharging a molten metal 
and a molten slag is provided at the bottom of the lower zone. 
FIG. 4 is an explanatory sectional view of an apparatus for carrying out 
another embodiment of the third aspect of the present invention. 
The apparatus shown in FIG. 4 is different from that in FIG. 3 and the 
carbonaceous material feeding device 57 is not provided so that the 
feeding device penetrates the upper zone and the perforated plate 43 and 
are suspended, but the device 57 is provided so that the carbonaceous 
material is directly fed from an outside of the vertical furnace to the 
lower zone. Except for such feeding device 57, the other structure is 
quite the same in FIG. 3 and FIG. 4. According to the apparatus in FIG. 3, 
the carbonaceous material fed through the feeding device 57 is preheated 
during the passing through the upper zone, so that this is thermally 
advantageous but the structure of the feeding device 57 is somewhat 
complicated and said feeding device is exposed to a high temperature, so 
that the durability is lower than the apparatus shown in FIG. 4, while in 
FIG. 3, the feeding device 57 is not exposed to a high temperature, so 
that the durability is higher but the cold carbonaceous material is 
directly fed to the lower zone, so that this apparatus is more thermally 
disadvantageous than that shown in FIG. 3. 
The apparatus of this embodiment is characterized in that the tuyeres are 
provided at an upper stage and a lower stage. Because a large heat energy 
is needed for melting the preliminarily reduced one and reducing oxygen in 
the ore, so that if the tuyeres at the lower stage are not provided, even 
though the preliminarily reduced ore is melted at the tuyere top of the 
upper stage, the zone below the tuyere level of the upper stage is low in 
the temperature, so that the reduction of the molten ore owing to the 
solid carbonaceous material is not satisfactorily caused and the operation 
cannot be continued due to cooling down of the furnace but according to 
the present invention, the cooling down of the lower portion of the 
furnace can be completely prevented by burning the carbonaceous material 
at the lower portion of the furnace. 
The carbonization of the carbonaceous material effectively occurs at about 
500.degree. C. and the reaction efficiency lowers at a temperature lower 
than 500.degree. C. The carbonization can be effected at a reaction 
temperature higher than 700.degree. C. but tar component in the 
carbonaceous material volatilizes and becomes a gaseous state, so that in 
order to effectively recover tar in a liquid state by a separator, the 
temperature is preferred to be lower than 700.degree. C. Because if the 
reaction temperature becomes higher than 700.degree. C., the liquid 
component is decomposed and the conversion rate into hydrocarbon gas 
increases. 
The volatile matter in a carbonaceous material, such as coal, when the 
carbonization is efected with the above described temperature range, 
evolves a carbonized gas containing tar, hydrogen, methane and the like 
and this gas is taken out from an outlet 65 in the upper chamber A.sub.1 
and a liquid tar is separated and recovered in a separator 66 and the 
remained exhaust gas is recovered through a purifying apparatus 67 
including a desulfurizing apparatus. The recovered gas contains H.sub.2, 
CO, C.sub.m H.sub.n and the like and can be effectively utilized as a 
clean fuel gas, a reducing gas for ore, a starting gas to be used in 
chemical industry. Of course, this gas can be utilized as a source for 
heating air to a high temperature, which is supplied to the herein-after 
mentioned melt-reducing furnace. The recovered tar is subjected to another 
purifying treatment and is used as a starting material for chemical 
industry. 
The following examples are given for the purpose of illustration of this 
invention and are not intended as limitations thereof. 
The invention will be explained with respect to examples concerning the 
first aspect of the present invention. 
EXAMPLE 1 
This example was carried out following to the production system shown in 
FIG. 1. 
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(1) Iron ore MBR ore 
Grain size less than 2 mm 
Supplied amount 1,650 kg/hr 
(2) Carbonaceous solid reducing 
agent 
Kind coke 
Grain size 25-75 mm 
Supplied amount 660 kg/hr 
(3) Amount of air blown into 
1.500 Nm.sup.3 /hr 
the vertical furnace 
Blown air temperature 900.degree. C. 
Number of air blowing tuyeres 
Total 8 
In each of lower and upper stages 
4 
(The preliminarily reduced product 
is fed into 
4 tuyeres in the upper stage) 
Preliminary reduction ratio 
71% 
(4) Amount of pig iron produced 
1,100 kg/hr 
(5) Amount of slag formed 220 kg/hr 
______________________________________ 
EXAMPLE 2 
The example was carried out following to the production system shown in 
FIG. 2. 
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(1) Iron ore MBR ore 
Grain size less than 2 mm 
Supplied amount 2,610 kg/hr 
(2) Carbonaceous solid reducing 
agent fed into the prelimi- 
nary treating furnace: 
Kind Non-caking coal 
(F.C.: 74.8%) 
Grain size less than 3 mm 
Supplied amount 1,110 kg/hr 
(3) Amount of air blown into 
2,350 Nm.sup.3 /hr 
the vertical reducing furnace 
Blown air temperature 
900.degree. C. 
(4) Preliminary reduction ratio 
71% 
(5) Amount of pig iron produced 
1,710 kg/hr 
(6) Amount of slag formed 
364 kg/hr 
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The following merits are obtained in the first and the second aspects of 
the present invention. 
(1) Since powdery ore can be directly used without effecting the lump form 
step, energy and expense for the lump formation are not necessary and no 
countermeasure for NOx, SOx and dusts formed in the lump formation is 
needed. 
(2) The gas evolved in the vertical reducing furnace and the preliminary 
treating furnace is used as the gas for preliminarily reducing an ore, so 
that an equipment for preparing the reducing gas is not specifically 
provided. 
(3) The preliminarily reduced ore having a reduction ratio of 40-80%, which 
can be relatively easily obtained, can be produced without hindrance. 
(4) Inexpensive carbonaceous solid reducing agent can be used as a heat 
source and when non-caking coal powder is used, a gas containing 
hydrocarbons having a very high reducibility and tar can be obtained. 
(5) The gas blown into the melt-reducing furnace is mainly the preheated 
air and expensive oxygen is not necessarily needed. 
(6) The pretreatment, the preliminary reduction and the melt-reduction are 
carried out in the fluidized state, so that there is no limitation in the 
place where the preliminarily reduced ore is fed to the vertical reducing 
furnace and the melting and the reduction may be easily carried out. 
As the example, use of iron ore was shown but nickel ore, manganese ore, 
chromium ore, etc. may be used as the starting material for carrying out 
the present invention. 
With respect to an example concerning the third aspect of the present 
invention, an explanation will be made hereinafter. 
EXAMPLE 3 
This example was carried out following to the production system shown in 
FIG. 3. 
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(1) Iron ore MBR ore 
Grain size less than 2 mm 
Supplied amount 3,499 kg/hr 
(2) Solid reducing agent. 
Kind cokes 
Grain size average 45 mm 
Supplied amount 1,488 kg/hr 
(3) Amount of air blown into 
3,150 Nm.sup.3 /hr 
the vertical furnace 
Blown air temperature 
900.degree. C. 
(4) Preliminary reduction ratio 
71% 
(5) Amount of pig iron produced 
2,299 kg/hr 
(6) Amount of slag formed 
488 kg/hr 
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The following merits are obtained in the second aspect of the present 
invention. 
(1) Powdery ore or metal oxide can be used without effecting the lump 
forming step, so that energy and auxiliary materials for the lump 
formation are not necessary and NOx, SOx and dusts resulting from the lump 
formation are not formed. 
(2) The gas evolved from the coke packed bed can be used as the preliminary 
reducing gas, so that no equipment for preparing a reducing gas is needed. 
(3) High preliminary reduction ratio is not needed, so that the preliminary 
reduction is easy and a high gas utility is attained. 
(4) The preliminarily reduced ore or metal oxide is subjected to the 
melt-reduction as such, so that the lump formation, such as briquet is not 
necessary. 
(5) In the melt-reduction, expensive electric power is not necessary and 
the sufficient heat energy can be supplied by combustion of the solid 
reducing agent with oxygen by using two stage of tuyeres. 
(6) No coke having a high strength as in the iron making blast furnace is 
needed, so that expensive caking coal the source of which is few, is not 
necessary. 
(7) By providing a fluidized bed on the upper portion of the coke packed 
bed, the sensible heat of gas evolved in the coke packed bed can be 
effectively utilized. 
(8) The feeding of the preliminarily reduced product to the tuyeres of the 
upper stage adopts an overflow system from the upper portion of the 
fluidized bed, so that the feeding is very easy and the pressurizing of 
gas is not necessary.