JPS5918452B2 - Method for producing molten metal from powdered ore - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing molten metal by preliminary reduction and melt reduction of powdery or small granular ore containing metal oxides. The present invention relates to a method for producing molten metal by pre-reducing ore using a reducing gas and then melting and reducing the ore.

In recent years, ore raw materials containing iron oxide or various metal oxides have decreased in the form of lumpy ores and have become more powdery or small-grained ores, and the proportion of powdery ores will continue to increase in the future.

As a smelting method that directly uses granular ore, a common method is to pre-reduce the granular ore using a fluidized bed, and then melt and reduce the pre-reduced ore in an electric furnace, converter, or other melting furnace.

In this case, there are many methods in which a binder is added to the pre-reduced ore to agglomerate it into agglomerates, and the agglomerates are melted and reduced in a melting furnace. Not only does it require extra processing energy;
If firing is required after agglomeration, NOx is present in the gas discharged from the firing furnace when the fired lumps are produced.

There is a drawback that the cost for treating SOX, dust, etc. is also large.

In addition to the above-mentioned method, a method has also been proposed in which pre-reduced ore is melted and reduced in powder form using an arc furnace, a furnace that uses plasma or pure oxygen, but the method using an arc furnace consumes less electricity. Not only is the quantity enormous, but there are also restrictions on location, making it difficult to apply a method that uses a furnace that uses plasma on an industrial scale, and a method that uses a furnace that uses pure oxygen requires a high-temperature atmosphere. However, since it is not possible to preheat oxygen, there are still technical problems that need to be solved, such as a small amount of heat input and difficulty in maintaining a reducing atmosphere. There are also locational issues.

As described above, many problems remain in the prior art that require technical and economical solutions.

The present invention involves pre-reducing granular ore in a vertical smelting reduction furnace that has two stages, upper and lower, in which a packed bed of carbon-based solid reducing agent is formed and high-temperature air is blown into the lower part. In a method of manufacturing molten metal by blowing ore together with the air at a high temperature and melting and reducing it in an electric furnace, the metal oxide containing a reducing gas generated in the melting and reducing furnace is used for the preliminary reduction. The object of the present invention is to provide a method for producing molten metal from powdery ore, and the above object can be achieved by the method described in the claims.

Next, the present invention will be explained in detail.

According to the present invention, a smelting reduction furnace has a packed bed made of a carbon-based solid reducing agent, and preheated air or oxygen in addition to the preheated air is blown into the packed bed from the tuyeres, and at the same time, the above-mentioned Pre-reduced granular ore and flux, or mixed pre-reduced particles of granular ore and powder flux, are conveyed by air current and blown together through the tuyere, and these charges are placed around the tip of the siding. The molten metal is melted in a high heat region generated by the molten metal, and while the molten metal drips through the packed bed, the molten metal is reduced and accumulated in the hearth of the smelting reduction furnace together with the molten metal and slag,
Hot water is discharged from the electric furnace in a timely manner.

The pre-reduced charge is pre-reduced using the reducing gas discharged from the melting reduction furnace.

The purpose of the flux is to exhibit the function of a solvent promoter or a desulfurizing agent during melt reduction, and as the flux, limestone, silica, dolomite, serpentine, etc. are used depending on the properties of the ore.

For example, when the ore is poorly soluble such as chromium ore, the powdered ore and powdered flux are mixed in advance and then granulated using a fluidized granulation method to form mixed particles. After being transferred to a fluidized furnace and fluidized to dry in an electric furnace, it is further transferred to a fluidized firing furnace and fired, and further transferred to a fluidized pre-reduction furnace and pre-reduced in an electric furnace, and then it is made up of pre-reduced ore and 7 lacs. The easily soluble pre-reduced particles can also be melted and reduced in a melting reduction furnace.

By the way, a method of pre-reducing powdery ore and then melting and reducing the pre-reduced ore is known from Japanese Patent Publication No. 34-2103 and Japanese Patent Application Laid-open No. 53-142313. The former method uses powdered coal as the fuel and reducing agent, and the latter method uses reduced iron-adhered carbon.

However, according to the present invention, the carbon-based solid reducing agent charged into the vertical melting reduction furnace is preferably in the form of lumps, and furthermore, according to the above two known methods, oxygen at room temperature burns the fuel. However, according to the present invention, air preheated to a high temperature is mainly used, and oxygen can also be used as an auxiliary. This method differs from the above-mentioned known method in two respects.

Next, a system showing one embodiment of the present invention will be described with reference to FIG.

A powder or small particle metal oxide is supplied from a supply device 1 to a preliminary reduction furnace 2 .

On the other hand, part or all of the high temperature generated gas generated in the vertical smelting reduction furnace 3 and discharged through the generated gas discharge mechanism 4 is introduced into the reduction furnace 2 from the generated gas introduction mechanism 5 of the preliminary reduction furnace 2. Then, the metal oxide charged in the furnace is dried, heated, and pre-reduced using a fluidized method.

The pre-reduced ore thus pre-reduced is discharged from the pre-reduced ore discharge device 6 and passes through the guide pipe 7 and tuyere 8 shown by chain lines.
, 8', and is blown into the vertical furnace 3 together with the preheated air.

At this time, in order to facilitate the transfer of the preliminary reduced ore in the guide pipe 7, it is advantageous to pressurize a part of the generated gas discharged from the vertical furnace 3 using a booster 9 and use it as a carrier gas. .

In addition, the high-temperature air (hereinafter referred to as hot air) blown into the vertical furnace 3 has a temperature of 800 to 130% by the gas heating furnace 10.
The temperature is raised to 0°C.

Moreover, oxygen gas can also be blown in together with hot air.

In addition, flux can also be blown into the vertical furnace 3 with hot air to advantageously perform smelting and reduction together with the pre-reduced ore.

The reducing agent is charged into the vertical furnace 3 through a carbon-based solid reducing agent supply device 11, and a reducing agent packed layer is formed inside the furnace 3, and near the tip of the tuyere inside the furnace 3, A raceway was formed by the hot air, similar to the area near the tip of the blast furnace tuyere, and the 2000
A high temperature region of ~2500° C. is formed, and the prereduced ore blown into this region with hot air or added oxygen is immediately heated and easily melted.

While dripping down the lower part of the furnace 3, it is reduced to produce molten metal and molten slag, which are smelted and stored in the hearth, and are tapped out of the furnace from the tapping port 12 at a timely manner.

Note that the area around the raceway portion that forms the high temperature region is a packed layer made of lumpy carbon-based reducing agent, and the gas around the raceway portion has a low oxygen content, that is, a low oxygen partial pressure. The reduction of the pre-reduced ore melted in the raceway section in the furnace 3 is carried out very favorably.

According to the present invention, in addition to lump coke, lump char or coal can be used individually or in combination as the carbon-based solid reducing agent.

In addition, the height of the vertical furnace 3 can be made lower than that of a normal blast furnace, and the pre-reduced ore is supplied into the furnace 3 from the tuyere.
It is economically advantageous that a strong reducing agent such as that used in a blast furnace is not required, and therefore expensive coking coal is not required.

According to the present invention, the pre-reduced ore is once oxidized by oxygen in the hot air in the raceway section, and is heated and melted by the heat of reaction. This is advantageous in that it is easy to do so.

The preliminary reduction rate varies depending on the type of ore and other factors, but it is 40%
The best results can be obtained within the range of ~80%.

According to the present invention, a large amount of heat is required for the preheated pre-reduced ore, which is blown into the furnace together with hot air through the tuyere, to be melted and reduced near the tip of the tuyere. Even if the tuyere is melted, if there is insufficient heat supply in the lower part of the furnace, reduction of the molten material will not occur sufficiently, and in order to prevent operation from becoming impossible due to cooling of the hearth,
It is necessary to provide it in stages.

In this case, the pre-reduced ore is mainly supplied from the tuyere 8 located in the upper stage, the pre-reduced ore is melted near the tip of the upper tuyere, the lower part of the furnace is heated to a high temperature by the lower tuyere 8', and The amount of heat necessary to reduce the melt dripping from the vicinity of the tip of the mouth 8 is supplied.

Next, a second system showing one family of other embodiments according to the present invention.
The diagram will be explained.

In FIG. 2, the vertical furnace 3 for melting and reducing the pre-reduced ore can be a vertical furnace similar to that shown in FIG.
What is different from the system shown in FIG. 1 is that in FIG. In FIG. 2, powdered ore and flux are fluidized to form mixture particles using a fluidized granulator 20, and then the mixture particles are The mixture particles are fluidized and dried using the drying furnace 21 to form dry mixture particles.Then, the dry mixture particles are fluidized and fired using the calcination furnace 22 to form fired mixture particles, and then the pre-reduction furnace 24 is used to perform calcination. After pre-reducing the mixture particles, the pre-reduced mixture particles are charged into the melting reduction furnace 3 through the tuyere 8 and, if necessary, the tuyere 8'.

Next, each step will be explained in more detail.

Powdered or small granular ore and powdered flux are charged into a granulating device 20 from storage tanks 17 and 18, respectively, and granulated by a fluidization method while supplying water from a spraying device 19.
Mixture particles (hereinafter the mixture particles are simply referred to as particles) with Lux are prepared.

The size of the particles is preferably 3 m11 L or less in consideration of the subsequent steps of drying, calcination, preliminary reduction, and transportation between each step.

Next, the medium particles are fluidized and dried in a drying oven 21.

Since the drying temperature at this time is 200° C. or lower, the exhaust gas discharged from the firing furnace 22 in the next step can be used.

Next, the dry particles are transferred into a firing furnace 22 and subjected to fluidized firing.

The firing temperature is preferably 900°C or lower; if it is higher than 900°C, the particles will sinter and bond with each other, which will not only make fluid discharge from the firing furnace 22 difficult, but also cause the fluidization of the particles to stop. .

The heat source of the firing furnace is the reaction heat generated by burning a part of the generated gas discharged from the generated gas discharge mechanism 4 of the smelting reduction furnace 3 in the firing furnace 22 with air blown in from the air blowing pipe 23. be.

Next, the fired particles are transferred into the preliminary reduction furnace 24, and a part of the generated gas discharged from the generated gas discharge mechanism 4 of the smelting reduction furnace 3 is transferred into the furnace 24 from the lower part of the preliminary reduction furnace 24. Blow into the furnace to fluidize and reduce the particles.

The gas generated from the melting reduction furnace 3 is C09CO2,I(
2, H2O.

It is made of N2, etc., has a high content of reducing C09H2, and has a temperature of 600 to 1500°C.

Thus, the pre-reduced particles have a high pre-reduction rate.
Moreover, the more the material is charged into the melting reduction furnace 3 while being maintained at a high temperature, the more easily it melts in the furnace 3.

The preliminary reduction rate varies depending on the type of ore, but is approximately 40%.
It is preferable to keep it within the range of ~80%.

Particles discharged from the preliminary reduction furnace 24 are charged into the melting reduction furnace 3 via the supply device 25 and mainly the tuyere 8 .

The supply device 25 can also be a mechanism that uses N2 or generated gas discharged from a smelting reduction furnace to convey airflow.

Note that the smelting reduction in the smelting reduction furnace 3 is the same as described for the system diagram in Figure 1, but in order to make the smelting reaction in the furnace 3 more smooth, flux may be added to the furnace 3 as necessary. You can also.

By the way, the size of particles granulated by a fluidized granulator is 3
If it is less than 11t11L, it is possible to use a gas conveyance method for transfer between each process, the amount of gas required for fluidization in each process is small, and the reaction in the melting reduction furnace proceeds quickly, which is advantageous. It is.

According to the system system shown in FIG. 2, the following advantages are produced.

1) When smelting poorly soluble chromium ore, for example, if pre-reduced particles in which chromium powder iron and 7 lux powder are intimately mixed are charged into a smelting reduction furnace, it will melt easily and the reaction will proceed quickly. do.

2) The gas generated from the melting reduction furnace can be sequentially used in each step of preliminary reduction, calcination, drying, and granulation.

Next, the present invention will be explained with reference to examples.

Example 1 The present invention was implemented in a test reactor using the system system shown in FIG.

The results are shown below. 1) Brand of iron ore: MBR Ore particle size: 277211L or less Supply amount: 1650 kg/hr 2) Type of carbon-based solid reducing agent: Coke particle size: 25-75 Ho supply amount: 660 rot/hr 3) Vertical furnace Air flow rate: 1500 Nm3/hr Air blowing temperature: 900°C Air blowing tuyere: 8 each, 4 upper and lower (preliminary reduction product is supplied to the upper 4) Preliminary reduction rate near 1% 4) Pig iron production volume: 1100@/hr 5) Skug discharge amount: 220@/hr Example 2 The present invention was implemented in a test furnace using the system shown in FIG.

The results are shown below. ■) Granulation 0 iron ore with granulator MBRore particle size -1mm supply amount 580kg
/hrO flux limestone particle size - 100 mha supply amount 280 kV'hr silica stone grain flea 100 mha supply amount 80
h/F1rO bentonite 2% addition 0 particles after granulation - 2 dragons 2) Drying and firing Drying temperature 150°C Calcining temperature 900°C 3) Pre-reduction Reduction temperature 900°C Reduction rate 65% 4) Melting reduction furnace 0 pig iron production 1080@/hr O slag discharge amount 350 kg/hr Example 3 The present invention was implemented in a test furnace using the system shown in FIG.

The results are shown below. ■) Brand of chromium ore: Chrome ore from the Philippines Particle size: 0.411m or less Supply rate: 420 kg/hr 2) Type of carbon-based solid reducing agent: Coke particle size: 20-40 Dragon supply rate: 610ky/hr 3 ) Amount of air blown to the vertical furnace: 1450 Nm3/hr Blow temperature: 950°C Blow tuyeres: 4 each on the top and bottom, 8 in total (preliminary reduction product is supplied to the upper 4 tuyere) Preliminary reduction rate: 31% 4) Ferrochrome Production: 230@/hr Composition: Cr
54.6%, C6.9%, Si 5.5%5) Slag discharge amount: 350 ky/hr Example 4 The present invention was implemented in a test furnace using the system shown in FIG.

The results are shown below. 1) Manganese ore: Australian manganese ore particle size: 1 or less Supply rate: 490 kg/hr 2) Type of carbon-based solid reducing agent: Coke particle size: 20-40m11L Supply rate: 420ky/hr 3) Vertical furnace Air flow rate: 1520 Nm3/hr Air blowing temperature: 900°C Air tuyeres: 8 each, 4 on the upper and lower tuyere (preliminary reduction product is supplied to the upper 4) Preliminary reduction rate: 55% 4) Ferromanganese production amount :260ky/hr Composition:
Mn 75.2%, C7.2%, Si 1.2%5
) Slag discharge amount: 220@/hr Example 5 The present invention was implemented in a test furnace using the system shown in FIG.

The results are shown below. 1) Brand of nickel ore: Nickel ore from New Caledonia Particle size: 1m11 or less Supply amount: 2620ky/hr 2) Type of carbon-based solid reducing agent: Coke particle size: 30-50 Homo Supply amount: 93 ohy/hr 3) Amount of air blown to the vertical furnace: 1520 Nm3/hr Air blowing temperature: 900°C Air tuyere: 4 each on the top and bottom, 8 in total (preliminary reduction product is supplied to the upper 4 tuyere) Preliminary reduction rate: 64% 4) Ferro Nickel production i: 370 rot/hr
Composition: Ni 17.2%, Si 4.2%, C2, 3%5)
Slag discharge amount: 2250 ky/hr Example 6 The present invention was implemented in a test furnace using the system shown in FIG.

The results are shown below. 1) Brand of iron ore: MBR Ore particle size: 1 mm or less Supply rate: 450ky/hr Silica sand: Iwaki silica sand particle size: 0.5 dragon or less Supply rate: 170ky/hr 2) Type of carbon-based solid reducing agent : Coke particle size: 25~5Qmm Supply amount: 590 phantom/hr 3) Air flow rate to vertical furnace: 1420 Nm"/hr Air blowing temperature: 910°C Air blowing tuyere: 4 each on the upper and lower sides, 8 in total (4 on the upper row) ) Iron ore preliminary reduction rate: 58% 4) Ferrosilicon production: 330 kg/hr Composition: 5i21.3%, CO0,6% 5) Slag discharge: 270 @/hr Implemented Example 7 The present invention was implemented in a test reactor using the system system shown in FIG.

The results are shown below. ■) Iron ore brand: Carroll L-
7 Ore particle size: 1 mm or less Supply rate: 610 mm/hr Boron compound: Boron oxide particle size: 0.2 mm or less Supply rate: 110 mm/hr 2) Type of carbon-based solid reducing agent: Coke particle size: 20-40 Dragon supply amount: 650ky/hr 3) Air flow rate to vertical furnace: 1550 Nm3/hr Air blowing temperature: 920°C Air blowing tuyere: 4 each on the upper and lower sides, 8 in total (preliminary reduction product is supplied to the upper 4) Preliminary reduction rate of iron ore: 2% 4) Ferroboron production: 2410 kg/hr Composition:
B2.9%, Si 4.6%, C2.6% 5) Slag discharge amount: 450 @/hr or more According to the present invention, a comparatively inexpensive weak coal is produced without using expensive electricity or strong coking coal. Because it uses caking or non-caking coal and the reducing gas discharged from the smelting reduction furnace can be effectively used for preliminary reduction of ore, it is a metal oxide product that is expected to increase energy costs in the future. It holds great promise as a smelting method.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a system system according to a first aspect of the present invention, and FIG. 2 is a diagram showing a system system according to a second aspect of the present invention. DESCRIPTION OF SYMBOLS 1... Ore supply device, 2... Fluidized preliminary reduction furnace, 3... Melting reduction furnace, 4... Generated gas discharge mechanism, 5... ... Generated gas introduction mechanism, 6
...Preliminary reduced ore discharge device, 7...Guiding pipe, 8, 8'...Tuyere, 9...Booster, 10...・Gas heating furnace, 11... Carbon-based solid reducing agent supply device, 12... Tap water outlet, 20
...Fluidized granulation device, 21...Fluidized drying furnace, 22...Fluidized calcining furnace, 24...Fluidized pre-reduction furnace, 25... ...Feeding device.

Claims (1)

[Scope of Claims] 1. Reducing gas discharged from a vertical furnace having a plurality of tuyeres each provided in two stages, upper and lower, in which a packed bed of a carbon-based solid reducing agent is formed and high-temperature air is blown into the lower part. The pre-reduced ore obtained by pre-reducing the fluidized ore using the tuyeres is blown into the vertical furnace together with high-temperature air from at least the upper tuyere of the two upper and lower tuyeres, along with flux if necessary. A method for producing molten metal from powdery ore containing metal oxides, the method comprising melting and reducing the ore. 2 Using reducing gas discharged from a vertical furnace having a plurality of tuyeres each provided in two stages, upper and lower, in which a packed bed of carbon-based solid reducing agent is formed and high-temperature air is blown into the lower part, the following ( b) During the process of ~ to), the ore and 7
Particles of the fired mixture with lux are pre-reduced to obtain pre-reduced mixture particles, and these particles are blown into the vertical furnace together with high-temperature air from at least the upper tuyere of the two upper and lower tuyeres. A method for producing molten metal from powdery ore containing metal oxides, which is characterized by carrying out melt-reduction process (a) Fluidizing the powdery ore and powdery flux using the exhaust gas generated in the step (0) below. A process of creating raw mixture particles of ore and 7 lux by fluidized granulation while spraying water. (0) A step of transferring the raw mixture particles and producing fluidized dry mixture particles using the exhaust gas generated in the step e→ below. e→ A step of transporting the dry mixture particles and performing fluidized firing using a part of the exhaust gas generated in the vertical furnace to produce fired mixture particles. B) A step of fluidized pre-reduction of the fired mixture particles using a part of the exhaust gas generated in the vertical furnace to produce pre-reduced mixture particles.