JPS6360803B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an apparatus for producing molten metal by pre-reducing powdery ore containing metal oxides and then melting the ore, in which the pre-reduced ore is introduced from the pre-reduction furnace to the smelting-reduction furnace. This relates to a device for

In recent years, ore raw materials containing 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. Conventionally, binders and carbonaceous materials were added to powdery ore to process it into pellets and sintered ore and use it as agglomerates, but this not only required extra resources and energy for agglomeration. However, when firing is required, there is a drawback that the cost for treating NOx, SOx, dust, etc. in the gas discharged from the firing furnace is large.

Furthermore, when smelting chromium ore in an electric furnace, such as the production of ferrochrome by smelting chromium ore, the electricity consumption rate reaches several thousand KWH/t, making the cost extremely high in areas where electricity is expensive.

In view of the above circumstances, the present inventors have developed a method for producing molten metal by directly using powder ore without agglomerating it and producing molten metal without using electricity. We have developed and proposed a method of pre-reducing the product in the form of a smelter, blowing it into a vertical smelting reduction furnace together with high-temperature air through the tuyeres, and melting and reducing it (Japanese Patent Application No. 56-63294).

The present invention relates to a smelting reduction apparatus comprising a pre-reduction furnace and a smelting reduction furnace, and a device for transferring and blowing granular pre-reduced ore from the pre-reduction furnace to the smelting reduction furnace. The transfer of pre-reduced ore in the smelting reduction device must satisfy the following special conditions compared to normal powder transfer.

1. Since pre-reduced ore is discharged from the pre-reduction furnace at high temperature, phenomena associated with high temperatures must be taken into consideration.

2. In order to reduce the temperature drop of the pre-reduced ore, the shorter the transfer distance, the better.

3. It is necessary to branch out from the pre-reducing furnace to a number of tuyeres and distribute it evenly.

4. Since the pressure is higher at the tuyeres into which the pre-reduced ore is injected than in the pre-reduction furnace, it is necessary to prevent blockage due to the pre-reduced ore and backflow of the pre-reduced ore in the transfer pipe.

5. Since the carrier gas for injecting the pre-reduced ore is blown into the smelting reduction furnace together with the pre-reduced ore, it is desirable that the amount of the carrier gas be as small as possible.

6. Re-oxidation of pre-reduced ore during transportation can be prevented.

7. The amount of pre-reduced ore injected into each tuyere can be controlled. In particular, it must have a complete closing function.

8. Preliminary reduced ore in the transfer pipe becomes diluted and accidents such as tuyere blast gas blowing through the transfer pipe can be prevented.

An object of the present invention is to provide an effective device that satisfies the above special conditions and facilitates the transfer of pre-reduced ore.

To achieve the above object, the present invention is characterized in that, in a smelting reduction apparatus consisting of a pre-reduction furnace and a smelting reduction furnace, high-temperature granular pre-reduced ore is transferred from the pre-reduction furnace to the smelting reduction furnace. An introduction pipe for blowing the ore into the tuyere branch pipe of the smelting reduction furnace is connected to the lower end of the pipe, and a carrier gas blowing nozzle is connected to the introduction pipe on the tip side from the center of the joint position with the transfer pipe in the introduction pipe. The present invention is characterized in that an intermediate portion is interposed in the introduction pipe on the tip side from the nozzle opening to stop the self-propulsion of the pre-reduced ore.

A system showing one embodiment of a melt reduction apparatus using the apparatus of the present invention will be explained with reference to FIG.

The preliminary reduction furnace 2 is supplied with ore containing powdery metal oxides by the supply device 1 . Part or all of the high-temperature reducing gas discharged from the vertical melting reduction furnace 3 is introduced from below, and particulate flux, solid reducing agent, reducing gas, etc. are supplied from the supply port 4 as necessary. , drying, heating and pre-reducing the powder ore in a fluidized bed format. The pre-reduced ore is discharged from the discharge port 5 together with flux, passes through the transfer pipe 6 and the introduction pipe 7, and is blown into the melting reduction furnace 3 together with the high-temperature air in the tuyere branch pipe 8. The pre-reduced ore described in the present invention may be accompanied by the above-mentioned granular flux and solid reducing agent, and refers to those containing these.

Inside the melting reduction furnace 3, a packed bed is formed of a lumpy carbon-based reducing agent supplied by a supply device. The pre-reduced ore blown into the smelting reduction furnace 3 is melted inside the furnace 3 and reduced while dripping down the lower part of the furnace to produce molten metal and molten slag,
It is discharged from the furnace through the discharge port 13 in a timely manner. The present invention relates to the structure of the introduction pipe 7 for the pre-reduced ore to be transferred.

When injecting prereduced ore into a smelter reduction furnace, important issues regarding the melting of the prereduced ore within the smelter reduction furnace must be considered. If the injected pre-reduced ore is not sufficiently melted within the raceway 11 formed at the tip of the tuyere, it will rush into the carbon-based reducing agent packed bed in front of the raceway in a powder form, and the holes in this packed bed will melt. This causes clumping, making it difficult to proceed smoothly with melting reduction in the furnace. Therefore, it is necessary to smoothly melt the pre-reduced ore in the raceway. The key to smoothly melting the pre-reduced ore is to inject the most appropriate amount of pre-reduced ore to the amount of high-temperature blown air (including oxygen-enriched air) per tuyere, and to melt the excess pre-reduced ore. It is important not to inject

Even if the total amount of pre-reduced ore injected into multiple tuyeres is controlled to a predetermined amount, if the amount of pre-reduced ore injected into each tuyere varies, the amount may be larger. At the tip of the tuyere into which pre-reduced ore is injected, the melting phenomenon cannot be carried out sufficiently, which is one of the causes of furnace malfunction. This is particularly likely to be a problem in the case of ores containing metal oxides that are difficult to melt and difficult to reduce.

The inlet pipe having the structure of the present invention can control the amount of pre-reduced ore blown in by adjusting the amount of carrier gas, and can completely shut off the amount blown in when the carrier gas is stopped.

FIG. 2 shows one embodiment of the introduction tube 7. As shown in FIG. 2, an introduction tube 7 is connected to the lower end of the transfer tube 6. It is desirable that the introduction pipe 7 be sloped at an appropriate angle to facilitate the introduction of the pre-reduced ore into the tuyere branch pipe.

In order to precisely control the amount of pre-reduced ore injected into the introduction pipe 7, the carrier gas supply pipe 10 is first inserted into the introduction pipe 7, and the carrier gas injection nozzle is opened. Supplying the carrier gas in the form of the carrier gas supply pipe 10 shown in FIG. 2 is just one example, and it is possible to supply the carrier gas through the wall of the introduction pipe 7, or to have a plurality of carrier gas inlets. is also possible.

When the carrier gas is supplied from the blowing nozzle to the introduction pipe 7 through the carrier gas supply pipe 10, the pre-reduced ore filled in the transfer pipe 6 and the introduction pipe 7 is
The air is blown into the blown air of the tuyere branch pipe 8 branched from the main air pipe 14. The pre-reduced ore reaches the raceway 11 in the smelting reduction furnace together with the tuyere blown air, where a smelting reduction reaction occurs.

At this time, as mentioned above, the pressure inside the tuyere branch pipe 8 is higher than the pressure at the outlet 5 of the pre-reducing furnace, so the gas flows inside the transfer pipe from the tuyere branch pipe toward the outlet 5 of the pre-reducing furnace. is about to blow through,
It is important to prevent this, and to prevent backflow and blockage of the powdery pre-reduced ore to ensure smooth transfer. As a result of various studies, it was found that installing the carrier gas inlet nozzle opening closer to the tip of the introduction pipe 7 than the center of the joining position between the transfer pipe 6 and the introduction pipe 7 is effective for smooth transfer. It is.

As shown in Fig. 2, the distance from the carrier gas inlet nozzle opening to the joining position of the transfer pipe 6 and the introduction pipe 7 (with the joining position as the origin and the tip side of the introduction pipe 7 as positive) is defined as L. , if the inner diameter of the introduction pipe 7 is D, the suitable value of L/D depends on the physical properties, properties, transfer, supply conditions, etc. of the powder, and the range is O≦L/D≦10.
It is.

When L/D<0, that is, when the carrier gas blowing nozzle is opened at a position farther from the tip of the introduction tube 7 than the joining position of the transfer tube 6 and introduction tube 7, a part of the carrier gas will noticeably flow inside the transfer tube 6. The backflow prevents the smooth transfer of the pre-reduced ore in the transfer pipe 6, and in extreme cases, the powdery pre-reduced ore in the transfer pipe becomes diluted and the blown air of the tuyere branch pipe 8 becomes difficult to blow. cause

In addition, when L/D>10, the transport capacity of the carrier gas for pre-reduced ore decreases, and there are many cases where the pre-reduced ore becomes clogged near the joint between the transfer pipe 6 and the introduction pipe 7, making it unsuitable. It is.

Next, the introduction pipe 7 of the present invention is provided with an intermediate portion 9 for stopping the self-propulsion of the pre-reduced ore in the middle of the introduction pipe 7 on the tip side from the opening position of the carrier gas blowing nozzle.

This intermediate portion 9 functions to stop the self-propulsion of the pre-reduced ore in the introduction pipe when the carrier gas injection is stopped, and ensures stability and controls the amount of pre-reduced ore blown during the injection of the carrier gas. It is extremely effective in improving sexual performance. The angle of inclination of this intermediate part 9 may be horizontal, but it is 1/2 of the angle of repose of the powder or granular material used.
It is also possible to have a downward slope or a slight upward slope. In the system of the fluidized bed discharge port 5, transfer pipe 6, and inlet pipe 7 of the pre-reduction furnace, this intermediate part 9 is the part where the self-propelled action by the power of the pre-reduced ore is the least, and it controls the amount of pre-reduced ore injected. Increases the sensitivity of action.

If the length of the intermediate part where the self-propulsion of the pre-reduced ore is stopped is l, and its inner diameter is d, then the preferred value of l/d depends on the physical properties and properties of the powder, the transfer and supply conditions, and the slope of the introduction pipe 7. , the slope of the intermediate portion, etc., and the range is 1≦l/d≦10.

If l/d<1, that is, the length of the intermediate portion is smaller than the diameter of the intermediate portion, the transfer of ore cannot be completely stopped when the carrier gas is stopped, and the function of preventing backflow of the blown gas will be impaired.

On the other hand, if l/d>10, the movement of the powder in the intermediate portion becomes unstable, which is inappropriate.

Since the present invention is configured as described above, it is possible to smoothly and stably supply high-temperature pre-reduced ore into a high-pressure tuyere branch pipe, and to stably stop the supply.

In addition, in general handling of powder,
Although a feeder having a mechanical structure is used to control the amount of injection, it is not advisable to use these methods in the present invention because it is necessary to transport the extremely high temperature pre-reduced ore.

Shutoff valve 1 is installed for emergency use to close the transfer pipe in the event that the blast gas blows through the transfer pipe.
It is also possible to install 5.

Next, a specific example using the device of the present invention will be given and its effects will be explained. The present invention is of course not limited to the following examples.

Example 1 Melting reduction furnace inner diameter 1.2 m 2 Pre-reduction furnace inner diameter 1.1 m 3 Blower tuyere 4 upper tier (powder injection) 4 lower tier 8 in total 4 Air flow rate 1200 Nm ³ /hr 5 Transfer pipe inner diameter 35 mm Introductory pipe inner diameter (D) 35mm Distance from the joint position of the transfer pipe with the introduction pipe to the carrier gas inlet (L) 105mm L/D 3 Middle part Angle Horizontal l/d 2.5 6 Carrier gas type N _2The above test furnace ferrochrome smelting operation from powdered chromium ore (average particle size 0.2 mm) and pig iron smelting operation from powdered iron ore (average particle size 0.37 mm). We were able to stably transport and inject pre-reduced ore into the smelting reduction furnace. The method of the present invention is, of course, effective for various ores, not limited to the ores of this embodiment.

The effects of the present invention as described above can be summarized as follows.

1. The fluidized bed preliminary reduction furnace and the smelting reduction furnace can be connected with each other with good controllability through multiple transfer pipes and introduction pipes.
It is also possible to stop the supply of preliminary reduced ore.

2 Pre-reduced ore does not flow back even though the pressure in the smelting reduction furnace is higher than the pressure in the pre-reduction furnace.

3. The pre-reduced ore is transferred through the transfer pipe by gravity, and is blown only in the introduction pipe section with the aid of carrier gas, so smooth injection of the pre-reduced ore can be achieved with a very small amount of carrier gas.

4. Pre-reduced ore can be injected into the smelter reduction furnace at higher temperatures due to the small amount of carrier gas required.

5. By adjusting the flow rate of the carrier gas, it is easy to distribute a predetermined amount of pre-reduced ore to each tuyere.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a melting reduction apparatus, and FIG. 2 is a partial sectional view of an embodiment of the present invention. 1...Powdered ore supply port, 2...Preliminary reduction furnace, 3...
Melting reduction furnace, 4... Supply port for powdery flux, solid reducing agent, reducing gas, etc., 5... Pre-reduction furnace outlet, 6... Transfer pipe, 7... Introducing pipe, 8... Tuyere branch pipe, 9
...Introduction pipe middle part, 10...Carrier gas supply pipe, 11...
Raceway, 12...Solid carbon-based reducing agent supply device, 13...Discharge port for molten metal and molten slag, 14
...Blower main pipe, 15...Shutoff valve.

Claims (1)

[Claims] 1. In a smelting reduction apparatus consisting of a pre-reduction furnace and a smelting reduction furnace, the ore is placed at the lower end of a transfer pipe that transfers high-temperature granular pre-reduced ore from the pre-reduction furnace to the smelting reduction furnace, and the ore is placed inside the tuyere branch pipe of the smelting reduction furnace. An introduction pipe is connected to the introduction pipe, and a carrier gas blowing nozzle is opened in the introduction pipe toward the distal end from the center of the joint position with the transfer pipe in the introduction pipe, and at the middle of the introduction pipe on the distal side from the nozzle opening. 1. A device for transferring and blowing pre-reduced ore, characterized in that an intermediate portion for stopping self-propulsion of the pre-reduced ore is interposed therein.