JPH0561323B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a smelting reduction technique for producing pig iron using iron ore powder and coal.

[Conventional technology]

Recently, as seen in Japanese Patent Application Laid-Open No. 58-217615, we conducted an experiment on a circulating fluidized bed pre-reduction reactor, and found that a pre-reduction reactor with a scale of about 15-30 t/d can reduce
The amount of ore falling is 300Kg/h, and depending on the type of ore and operating conditions, a considerable amount of ore is expected to fall. Generally, powdered ore is used, but it is considered extremely difficult to completely prevent ore from falling due to the fact that some of the ore has a coarse particle size and statesking of ore occurs during operation.

Figure 2 is a vertical cross-sectional view of the conventional device, with riser 1
The fine ore which has been preliminarily reduced by the reducing gas 20 blown up from below is separated from the reducing gas in the cyclone 2 and is returned to the riser 1 via the downcomer 3 and the fine ore circulation device 4. The raw material powder ore 11 is supplied into the riser outlet air stream, and the pre-reduced ore is extracted from the downcomer 3.

[Problem to be solved by the invention]

Generally, in a circulating fluidized bed pre-reduction furnace as shown in FIG. 2, it is difficult to completely prevent ore from falling from the lower part of the riser 1, which falls against the upward flow of the reducing gas 20.

The present invention provides an effective method for treating fallen mines.

[Means to solve the problem]

The means of the present invention will be explained with reference to FIG. 5
is a smelting reduction furnace having two-stage tuyeres, and reducing gas 20 generated from the reduction furnace 5 is supplied through an exhaust gas duct 8 into the riser 1 of the circulating fluidized bed pre-reduction furnace. On the other hand, the raw material powder ore 11 is
is supplied to the outlet of the cyclone 2, collected by cyclone 2,
It stays in the downcomer 3, is returned to the riser 1 again by the circulation device 4, and is circulated.

Normally, the reduced ore is discharged from the downcomer 3, stored in the hopper 7, and introduced into the upper tuyere of the reduction furnace 5.

The present invention provides a hopper 6 below the riser 1,
The fallen ore is charged into the top of the reduction furnace 5.

[Effect]

According to the present invention, the ore that has fallen from the riser 1 of the circulating fluidized bed pre-reduction furnace is temporarily stored in the hopper 6, and the charging pipe through which the ore can be charged from the hopper 6 to the top of the smelting reduction furnace 5. By providing this, the fallen ore can be directly melted and reduced.

〔Example〕

FIG. 1 is an overall flow diagram of an embodiment of the method of the present invention. In Figure 1, the amount of raw ore powder 11 supplied to the preliminary reduction furnace is 600 kg/h, the amount of gas generated 20 from the smelting reduction furnace is 3000 Nm ³ /h, the amount of fine ore retained in the riser is 800 kg, and the amount of raw ore powder 11 is 600 kg/h. The average particle size of
50μm, and the apparent specific gravity of raw material powder ore is 4.2, the amount of pre-reduced ore 15 charged from the upper tuyere of the smelting reduction furnace is 400 to 450 kg/h, and the amount of pre-reduced ore 15 is charged from the top of the smelting reduction furnace 5. The amount of fine ore produced is 100 to 150 kg/
It was h.

As can be seen from this result, in the operation of the above-mentioned circulating fluidized bed pre-reduction furnace, the amount of fallen ore is 15 to 25% of the amount of raw powder ore supplied, and this is not charged to the smelting reduction furnace and is removed outside the system. Considering the throughput, a considerable amount of ancillary equipment is required to discharge the waste into a tank, pre-process it again, and then charge it into a preliminary reduction furnace, or to charge it into a smelting reduction furnace. With the method of the present invention, fallen ore can be easily treated without the need for complicated incidental equipment as described above.

〔Effect of the invention〕

According to the present invention, the thermal efficiency and yield are improved by directly charging the fallen ore from the preliminary reduction furnace to the smelting reduction furnace.

[Brief explanation of the drawing]

Fig. 1 is an overall flow diagram of an embodiment of the present invention;
The figure is a longitudinal sectional view of a circulating fluidized bed pre-reduction furnace. 1... riser, 2... cyclone, 3... downcomer, 4... ore circulation device, 5... smelting reduction furnace, 6... falling ore hopper, 7... preliminary reduced ore hopper, 8... exhaust gas duct.

Claims (1)

[Claims] 1. In the operation of a smelting reduction furnace having a circulating fluidized bed type pre-reduction furnace, the fallen ore generated in the pre-reduction furnace is temporarily stored in a hopper, and the fallen ore is transferred to the carbonaceous fluid in the smelting reduction furnace. A method for treating fallen ore in a preliminary reduction furnace, characterized by charging the ore within a layer.