JPH0613252Y2 - Fluidized bed preliminary reduction furnace - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention relates to the smelting reduction of powdery ore, in particular, the reserve of the powdery ore by connecting to a smelting reduction furnace used when directly producing molten metal from powdery ore. The present invention relates to a fluidized bed preliminary reduction furnace used for reduction.

(Prior art) Regarding iron ore and other metal ore resources, there is a tendency for lumpy ones to decrease and powdery ones to increase, but currently, in order to improve the grade of low-grade ores, flotation and magnetic separation This trend is expected to increase in the future, partly because of the active promotion of.

Incidentally, in recent years, a so-called smelting reduction method has been developed in which molten metal is directly produced from powdered ore in response to the increase in the amount of powdered ore used as described above.

There are various types of such smelting reduction method, but the inventors have been engaged in the research and development of the smelting reduction method using a solid smelting reduction furnace and a fluidized bed preliminary reduction furnace for many years, Also reported many development results.

For example, Japanese Patent Publications Sho 59-18452, No. 50-18453, and No. 62-5207
Nos. 59-80703 and 62-56537.

(Problems to be solved by the invention) In the smelting reduction method, high temperature exhaust gas from a smelting reduction furnace is introduced into a fluidized bed preliminary reduction furnace to form a fluidized bed, and high temperature exhaust gas (fluidized reducing gas) is used to produce powdery ore. Have been preliminarily reduced. And pre-reduced powdery ore (hereinafter referred to as pre-reduced ore)
Is introduced into the smelting reduction furnace through the discharge pipe from the discharge opening formed in the furnace side wall.

In the furnace where pre-reduction is in progress, the whole or part of the ore layer is at or above the temperature (upper limit temperature) at which it can operate stably, and deposits due to ores, additives, or dust in the reducing gas are generated. It is easily generated mainly on the inner wall of the furnace. On the other hand, since the discharge port is open facing the inner wall of the furnace, deposits are generated around the discharge port, and deposits flow down from the surrounding furnace wall to the discharge port. It gradually accumulates at the discharge port and hinders the discharge of the preliminary reduced ore, and eventually the discharge port is blocked and the discharge of the preliminary reduced ore becomes impossible.

An object of this invention is to realize a stable operation by providing a structure capable of avoiding clogging of the discharge port on the side wall of the furnace by deposits.

(Means for Solving the Problem) This invention provides an inlet for fluidized reducing gas at the bottom of the furnace,
A fluidized bed preliminary reduction furnace in which a discharge port for a preliminary reduction product is opened on a side wall of the furnace, wherein a discharge pipe is connected to the discharge port and a tip of the discharge pipe is projected into the furnace. .

Further, it is advantageous in practice that the discharge pipe is formed by connecting a small-diameter pipe and a large-diameter pipe forming the tip end thereof, or that a filter is provided at the opening.

(Operation) In the fluidized bed preliminary reduction furnace according to the present invention, the tip of the discharge pipe connected to the discharge port is projected from the inner wall of the furnace into the furnace. Therefore, even if the deposits on the furnace wall flow down, the deposits flow on the outer peripheral wall of the tip of the discharge pipe and do not directly flow into the discharge port. Also, there is a risk that deposits will be generated at or around the exhaust port and block the exhaust port, but the flow velocity of the fluidized reducing gas in the fluidized bed becomes faster as it gets closer to the center of the furnace from the furnace wall, so Since the tip of the protruding discharge pipe is exposed to the fluidizing reducing gas at a higher flow rate than the furnace wall, it is difficult for the deposits to be generated and adhered, and the attached deposits are easily peeled off. Therefore, it is possible to avoid the clogging of the discharge port due to the deposits.

The length of the projection of the discharge pipe from the inner wall of the furnace depends on the diameter of the discharge pipe.
0.5 to 2 times is preferable. This is because if it is too long, the smooth fluidization of the ore in the furnace is hindered, or the ore that is fluidized causes mechanical wear of the discharge pipe itself. If it is too short, the deposits grown on the furnace wall will easily flow into the discharge pipe.

In addition, if the discharge pipe consists of a small diameter pipe and a large diameter pipe, the preliminary reduced ore that has flowed into the tip of the discharge pipe will not clog because the diameter of the subsequent pipe is large, and the discharge of the preliminary reduced ore will not be hindered. Absent. This also applies to the case where a filter is provided at the opening of the discharge pipe, that is, only the pre-reduced ore having a particle size that can pass through the filter passes through the discharge pipe, so that the pipe is not clogged.

(Example) Now, a preferred example of the fluidized bed preliminary reduction furnace according to the present invention will be described below.
Shown in the figure.

In the figure, 1 is an inlet for fluidized reducing gas 2 from the smelting reduction furnace,
3 is a fluidized bed, 4 is a raw material supply port facing the fluidized bed 3, 5 is an outlet for sending the pre-reduced ore from the fluidized bed 3 to a smelting reduction furnace, and 6 is a projection from the outlet 5 into the furnace for connection. The discharge pipe and 7 which are shown are dispersion plates. Here, the projection length l of the discharge pipe 6 into the furnace may be set in the range as described above.

If the gas flow velocity in the fluidized bed preliminary reduction furnace is so high that the ore is scattered from the furnace, a cyclone is attached to the furnace to collect the ore that has jumped out of the furnace and return the collected ore to the furnace again. It is also possible to use a circulation type fluidized pre-reduction furnace.

In the fluidized bed pre-reduction furnace shown in FIG. 2, the discharge pipe 6 is a combination of a small diameter pipe 6a arranged on the tip side and a large diameter pipe 6b coaxially connected to the discharge pipe 6. The preliminary reduced ore that has flowed into the tip (small diameter pipe 6a) does not become clogged because the diameter of the subsequent discharge pipe (large diameter pipe 6b) is large.

Further, the fluidized bed pre-reduction furnace shown in FIG. 3 has a filter 8 which is detachably attached in a direction crossing the axis of the discharge pipe 6. The filter 8 is formed by opening a plurality of holes or slits, and only the pre-reduced ore that can pass through the discharge pipe 6 that can pass through these holes or slits is introduced into the discharge pipe 6.

It is also effective to install the filter 8 shown in FIG. 3 on the discharge pipe 6 shown in FIG.

Next, the operation performed by applying the fluidized bed preliminary reduction furnace of FIG. 2 will be specifically described.

Fluidized reducing gas (CO: 23ONm ³ / h, H ₂ : 320Nm ³ / h and N ₂ : 31) in a fluidized bed preliminary reduction furnace with a tower diameter of 700mm and a tower height of 4500mm.
0Nm ³ / h, 775 ℃) was introduced to reduce iron ore with an average particle size of 0.5 mm.
Stable operation of kg / h could be performed. The inner diameter of the discharge pipe was 40 mmφ for small diameter pipe and 50 mmφ for large diameter pipe.

The fluidized bed preliminary reduction furnace shown in Fig. 3 (exhaust pipe inner diameter: 50 mmφ:
Similar results were obtained when the same operation was performed using a filter having a pore size of 5 mmφ.

(Effect of the Invention) According to the present invention, the discharge port or discharge pipe that controls the discharge of the pre-reduced ore is not clogged with the ore, so that stable operation can be always realized.

[Brief description of drawings]

FIG. 1 is a sectional view of a fluidized bed preliminary reduction furnace according to the present invention, and FIGS. 2 and 3 are sectional views showing another example of the fluidized bed preliminary reduction furnace according to the present invention. DESCRIPTION OF SYMBOLS 1 ... Inlet port, 2 ... Fluidization reducing gas 3 ... Fluidized bed, 4 ... Raw material supply port 5 ... Discharge port, 6 ... Discharge pipe 6a ... Small diameter pipe, 6b ... Large diameter pipe 7 ... Dispersion plate, 8 ... Filter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kazuhiko Sato 1 Kawasaki-cho, Chiba-shi, Chiba, Kawasaki Steel Co., Ltd. Technical Research Division (72) Takashi Ushijima 1 Kawasaki-cho, Chiba, Chiba Kawasaki Steel Co., Ltd. Research headquarters

Claims (3)

[Scope of utility model registration request] 1. An inlet for fluidized reducing gas is provided at the bottom of the furnace,
A fluidized bed preliminary reduction furnace in which a discharge port for a preliminary reduction product is opened on a side wall of the furnace, wherein a discharge pipe is connected to the discharge port and a tip of the discharge pipe is projected into the furnace. 2. The fluidized bed preliminary reduction furnace according to claim 1, wherein the discharge pipe is formed by connecting a small-diameter pipe and a large-diameter pipe forming a tip portion thereof. 3. The fluidized bed pre-reduction furnace according to claim 1, wherein the discharge pipe is provided with a filter at its opening.