JPH046766B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a method for collecting and recycling dust generated from a vertical smelting-reduction furnace for powdered ore at a high temperature and supplying the same to a vertical smelting-reduction furnace. It is related to the device.

<Conventional Technology> A large number of research and developments have been conducted on iron manufacturing methods that do not involve blast furnaces, and one of them is the smelting reduction method.

Since the smelting reduction method is a method of reducing ore in a molten state, the temperature inside the furnace is high above 1600°C, which has the disadvantage that slag components tend to evaporate and a large amount of dust is generated. The amount of dust generated differs depending on the method, but the higher the furnace top temperature, the more dust generated. For this reason, recycling dust in melting reduction furnaces, especially recycling dust while still at high temperatures, has become a major issue.

As a countermeasure to this, Japanese Patent Application Laid-open No. 60-258021 discloses that a slanted powder supply pipe and a powder discharge pipe are connected to the lower part of the supply side and the discharge side of the cylinder, which are separated by a partition plate having a passage slit at the upper part. However, by providing a perforated plate that crosses the bottom of the cylinder and a gas feed pipe for powder fluidization connected below the plate, it is possible to quantify powder under high temperature conditions by simply adjusting the gas feed rate. A device for quantitatively supplying powder is disclosed.

<Problems to be Solved by the Invention> The method disclosed in Japanese Patent Application Laid-open No. 60-258021 has the disadvantage that when injecting pre-reduced ore from the low-pressure pre-reduction furnace side to the high-pressure smelting reduction furnace side, powder The bulk specific gravity of
When the powder is large, such as an ore of about 1.5 to 2.5 g/cm ³ , the powder flow descending in the inclined supply pipe is smooth, and no shelving or blow-through occurs in the inclined supply pipe.

However, the bulk specific gravity of dust mainly composed of carbon and slag components is about 0.4 to 0.6 g/ ^cm3 , and in the case of dust with a small bulk specific gravity, the flow of dust descending in the inclined supply pipe is unstable and the shelf Dragging occurred frequently and stable blowing was not possible. FIG. 3 is a schematic diagram of the shelf suspension of the inclined supply pipe.

The present invention aims to prevent dust shelving in a gravity transport pipe, which occurs in conventional methods, when recycling dust generated in a vertical smelting reduction furnace, and to enable stable dust recycling. This is the purpose.

<Means for solving the problem> The present inventors have found through experiments that shelving occurs frequently in the case of dust with a small bulk specific gravity because the powder flows in from below the perforated plate to adjust the blowing speed. It was found that 40-50% of the powder fluidizing gas flows into the gravity-transported inclined feed pipe and comes into countercurrent contact with the dust in the inclined feed pipe.

In the case of ore powder having a large bulk specific gravity, it was found that less than 5% of the powder fluidizing gas flows into the inclined supply pipe.

The present invention has been made based on the above knowledge, and it is believed that it is effective to separate the gas flow flowing into the inclined supply pipe side from the falling dust flow as much as possible, and the majority of the gas flowing inside the inclined supply pipe is in the form of bubbles. The present invention has been completed by taking advantage of the fact that the supply pipe passes along the upper wall of the inclined supply pipe.

The present invention collects dust generated from a vertical smelting reduction furnace while still at high temperature, transports the dust by gravity through an inclined supply pipe, guides it to a quantitative cutting device, and controls the cutting amount with the quantitative cutting device. In the method for recycling dust of a vertical smelting reduction furnace, the dust is supplied to a tuyere for blowing gas into the vertical smelting reduction furnace, and the dust is blown into the vertical smelting reduction furnace together with the gas. This device transports the dust by gravity while removing the gas flowing backwards.Furthermore, as a device for suitably carrying out the invention of the dust recycling method described above, the dust generated from the vertical melting reduction furnace is transported by high temperature. A cyclone that collects the dust as it is, a dust hopper that temporarily stores the collected dust, a quantitative cutting device located below the dust hopper, and an inclined supply pipe that transports the dust by weight from the dust hopper to the quantitative cutting device. , a dust recycling device for a vertical smelting-reduction furnace comprising a supply pipe that blows the dust cut out from the quantitative cutting device into the tuyeres of the vertical smelting-reduction furnace; A plurality of gas outlet ports are provided in the dust hopper, a gas path is provided connecting the gas outlet ports to the freeboard of the dust hopper, and a vibrator is provided in the inclined supply pipe.

<Operation> By transporting dust by gravity while separating and removing gas flowing backward through the inclined supply pipe, it is possible to prevent countercurrent contact between the dust flow and the gas flow in the inclined supply pipe, thereby preventing the occurrence of shelving. be able to.

<Example> An example of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is an explanatory diagram of the present invention, and FIG. 2 is an enlarged view of the main part of FIG. 1.

In the figure, A is a vertical smelting reduction furnace, 1 is a cyclone, 2 is a dust hopper, 3 is an inclined supply pipe, 4
5 is a quantitative cutting device, 5 is a blowing pipe, 6 is a blowing pipe, 7 is a carbonaceous solid reducing material hopper, and 8 is a plurality of tuyere groups installed in upper and lower stages. For example, by blowing high-temperature air under heating through the tuyere group 8, the carbonaceous solid reducing material is combusted and a high-temperature reducing atmosphere can be created in the furnace.

Dust generated from inside the furnace is collected by a cyclone 1 and accumulated in a dust hopper 2, and is blown into the furnace from an inclined supply pipe 3 through a quantitative cutting device 4 through a blowing pipe 5 for recycling.

Since the pressure in the furnace and the pressure in the dust hopper 2 are higher, the inclined supply pipe 3 is constantly filled with dust to prevent the gas from flowing back from the blower pipe 6, thereby acting as a powder seal.

In the present invention, in order to separate the gas flow flowing into the inclined supply pipe 3 side from the descending dust flow as much as possible, most of the gas flow inside the inclined supply pipe 3 becomes bubbles and is formed on the inner wall of the upper surface side of the inclined supply pipe 3. Taking advantage of the fact that the supply pipe passes along
was installed. In FIG. 2, arrows indicate the direction of gas flow.

In addition, a dedicated gas bypass pipe 11 was provided at the outlet of the dust hopper 2, where shelf suspension is likely to occur due to countercurrent contact between air bubbles and dust.

Note that the method of installing the gas path connecting the gas outlet provided on the upper wall of the inclined supply pipe 3 to the freeboard of the dust hopper is not limited to the form of this embodiment. Any form may be used as long as it can effectively prevent shelf hanging.

If the diameter d of the gas bypass pipes 10 and 11 is too small, the effect will be small, and with respect to the diameter D of the inclined supply pipe 3,
There is no problem if d/D≧0.15. Further, the gas outlet pipes 9 may be installed at approximately 1 m intervals.

Furthermore, in order to promote separation of the gas flow and the powder in the inclined supply pipe 3, the angle of the inclined supply pipe 3 is preferably 50 to 80 degrees with respect to the horizontal direction.

Furthermore, if a vibrator 12 is installed on the inclined supply pipe 3, the bubble separation effect is further improved. The type, installation position, and number of vibration exciters 12 are not particularly limited as long as they can effectively vibrate the upper-front inclined supply pipe 3, but the preferred installation position and number of vibration exciters 12 are at least below the hopper 2. One unit may be installed at the inclined supply pipe 3, and one unit at the entrance of the quantitative cutting device 4.

Next, specific examples of the present invention will be described. 1st
In the test furnace according to the example shown in the figure, ferrochrome smelting from powdered chromium ore and smelting from powdered iron ore were carried out under the following operating conditions. In addition,
Transparent heat-resistant glass was placed in a part of the inclined supply pipe to allow observation of the internal situation.

(1) Melting reduction furnace inner diameter: 1.2m Pressure: 1.3Kg/cm ² (2) Cyclone dust hopper pressure: 1.1Kg/cm ² (3) Powder injection tuyere: 3 on upper stage, 3 on lower stage, total 6 (4) Air flow rate: 1650Nm ³ /h (5) Inclined supply pipe inner diameter: 80mm Angle: 53° Height: 4.5m (6) Gas bypass pipe inner diameter: 25mm Gas extraction pipe diameter: 15mm (7) Shaker , Impact force: 28Kg Vibration frequency: 6000 times/min (8) Powder fluidization gas amount: 100N/min (9) As a result of sampling the dust properties generated from the furnace, bulk specific gravity: 0.6g/cm ³ Harmonic average Diameter: 1.5mm As a comparative example, a case was also conducted in which a blind plate was inserted at the connection between the gas bypass pipe and the inclined supply pipe. As a result, in the case of the present invention, no shelving occurs in the inclined supply pipe during the entire operation period, and it is possible to smoothly flow 30 to 50% of the fluidized gas to the exhaust gas system, allowing dust to be supplied and blown. The process proceeded extremely smoothly and the operation of the smelting reduction furnace was possible using stable dust recycling. Furthermore, the amount of inert gas to the tuyere tip can be reduced, and it has also become possible to improve the powder abrasion at the tuyere tip and the temperature drop in the furnace. but,
In a comparative example in which the function of the gas bypass pipe was stopped, the dust falling down the inclined supply pipe frequently became suspended, and the blowing stopped intermittently.If the stopping period reached a long time, the blowing gas to the tuyere A blow-through occurred, making operations extremely dangerous.

<Effects of the Invention> As described above, according to the present invention, it is possible to prevent shelf suspension of high-temperature dust in the inclined supply pipe, and also to allow 30 to 50% of the fluidizing gas, which is mainly inert gas, to flow to the exhaust gas system. It is possible to achieve smooth operation of the vertical smelting reduction furnace while recycling dust, such as preventing powder abrasion at the tip of the tuyeres and reducing the ingress of wasteful inert gas into the furnace.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, FIG. 2 is an enlarged view of the main part of FIG. 1, and FIG. 3 is a schematic diagram of a hanging shelf. 1...Cyclone, 2...Dust hopper, 3
... Inclined supply pipe, 4 ... Quantitative cutting device, 5 ... Blow pipe, 6 ... Blow pipe, 7 ... Carbonaceous solid reducing material hopper, 8 ... Tuyere, 9 ... Gas take-off pipe, 10 ，
11... Gas bypass pipe, 12... Vibrator, A...
...Vertical melting reduction furnace.

Claims (1)

[Claims] 1. Dust generated from a vertical melting reduction furnace is collected while still at high temperature, and the dust is transported by gravity through an inclined supply pipe to a quantitative cutting device, and is cut out by the quantitative cutting device. In the method for recycling dust in a vertical smelting reduction furnace, the dust is supplied to a tuyere for blowing gas into the vertical smelting reduction furnace while controlling the amount, and is blown into the vertical smelting reduction furnace together with the gas. A method for recycling dust in a vertical melting reduction furnace, characterized by transporting the dust by gravity while removing gas flowing backward through an inclined supply pipe. 2. A cyclone that repairs the dust generated from the vertical melting reduction furnace while it is still at high temperature, a dust hopper that temporarily stores the collected dust, a quantitative cutting device located below the dust hopper, and a quantitative cutting device that removes the quantitative cutting from the dust hopper. Recycling of dust from a vertical smelting-reduction furnace, which consists of an inclined supply pipe that transports dust by gravity to the extraction device, and a supply pipe that blows the dust cut out from the quantitative cutting device into the tuyere of the vertical smelting-reduction furnace. In the apparatus, a plurality of gas outlet ports are provided on the upper wall of the inclined supply pipe, a gas path is provided by connecting the gas outlet ports to the freeboard of the dust hopper, and a vibration exciter is provided in the inclined supply pipe. A dust recycling device for a vertical melting reduction furnace, which is characterized by being equipped with.