JPH03183716A - Circulation fluidized bed reduction apparatus - Google Patents

Abstract

PURPOSE:To recover powdery ore collected in a cyclone and to pre-reduce the recovered powdery ore in a pre-reduction furnace with high yield by setting plural cyclones in series to the fluidized bed type pre-reduction furnace for powdery ore and independently circulating the recovered powdery ore in a storing tank at lower part of the cyclone to the pre-reduction furnace. CONSTITUTION:For example, by blowing high temp. reducing waste gas 2 containing CO, etc., generated from a smelting reduction furnace at the next process from a gas supplying hole at bottom part in the pre-reduction furnace 1 containing the powdery ore 3, fluidized bed of the powdery ore 3 is formed and the pre-reduction is executed. The pre-reduced powdery ore is stored into each of storing tanks 11, 21 after separated from the waste gas in the cyclones 10, 20 in the waste gas line connected in series, and also fresh powdery ore is supplemented from each of supplying holes 12, 22. By supplying a part of the pre-reduced powdery ore into the smelting reduction furnace at the next process from each of discharging holes 13, 23 and circulating the rest thereof directly into the fluidized bed type pre-reduction furnace 1 from each of circulating passages 14, 24, the powdery ore including fine ore is pre-reduced with high yield.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a circulating fluidized bed reduction apparatus for powdered ore.

[Prior Art] In recent years, a smelting reduction method for directly smelting and reducing fine ore has been developed.

In such a smelting reduction method, an apparatus is used that is a combination of a smelting reduction furnace and a circulating fluidized bed reduction apparatus that preheats and pre-reduces fine ore using the exhaust gas of the smelting reduction furnace.

The basic configuration of a circulating fluidized bed reduction device is a fluidized bed reduction furnace that forms a fluidized bed, a cyclone that performs solid fraction 111 (collecting ore), and a v-type system that returns the collected ore to the fluidized bed reduction furnace.
It consists of three parts of the IIFj pathway.

The ore collection rate in such a circulating Fift fluid bed is determined by the performance of the cyclone and the degree of pulverization of ore. If the degree of ore pulverization is the same, it is thought that the collection efficiency will be higher if multiple cyclones are installed in series than by a single cyclone.

When multiple cyclones are installed in series, the downstream cyclone has a smaller amount of collected particles and a finer particle size.

However, in the conventional technology, even if JI number of cyclones are installed in series, the circulation path for the collected ore to the fluidized bed reduction furnace is one collecting pipe. It was not possible to efficiently circulate fine ore powder to the fluidized bed reduction furnace. In addition, the downstream side of the cyclone is more likely to cause backflow of gas and ore, and the use of a plurality of cyclones actually reduces the collection efficiency.

The problems of the conventional device as described above will be explained using FIGS. 2 and 3.

FIG. 2 shows a skeletal diagram of a conventional device. The gas discharged from the fluidized bed reduction furnace 1 is passed through the first cyclone IO.
The fine ore is separated and sent to the second cyclone 20, where the remaining fine ore is separated again and discharged out of the system. The fine ore separated by the cyclone is stored in a storage tank 11, and a portion is extracted from the system through an outlet 13 and circulated through an ore circulation path 14 to a fluidized bed reduction furnace I. As shown in Figure 2, if the seal height of the ore in the storage tank 11 is lower than the opening of the return pipe 27 of the second cyclone, the ore collected by the second cyclone 20 will be trapped inside the return pipe 27. The gas with the fine ore from the first cyclone 10 flows back 6. Therefore, the first cyclone lO
The apparent efficiency of is reduced and the second cyclone 20 becomes inactive.

Figure 3 shows that the seal height of the fine ore in the storage tank 11 is at the second level.
The case is shown above the opening of the return pipe of the cyclone 20. In this case, the second cyclone 20
works, but the collected ore remains in the return pipe 27 and does not flow to the storage tank ll. Therefore, the second cyclone 20 becomes inoperable due to stagnation and solidification.

[Problems to be Solved by the Invention 1] Therefore, the present invention has a structure that prevents the backflow of gas and ore to the downstream cyclone and allows the collected ore to be efficiently returned to the fluidized bed reduction furnace.

[Means for Solving the Problems 1] The present invention provides a circulating fluidized bed reduction apparatus equipped with cyclones, in which a plurality of cyclones are coupled in series, and each cyclone series is independently provided with a storage tank for collected fine ore and a raw material. This is a circulating fluidized bed reduction device characterized by providing an ore supply port, a circulation path to the fluidized bed, and a ring source ore discharge port.

[Operation j] Figure 1 shows the device of the present invention. In the apparatus of the present invention, each cyclone was provided with a storage tank, and each was provided with a raw material supply port and a circulation path to the fluidized bed reduction furnace. The fine ore collected by the second cyclone is finer and smaller in amount than the fine ore collected by the first cyclone, so there is a possibility that the gas will flow backwards. Therefore, raw materials are supplied as described above and powder sealing is performed.

Since the apparatus of the present invention is constructed in this manner, the collection effect of each multi-stage cyclone is not diminished.

[Actual example 1: Iron ore from Australia was overcoated to 15 mm, and 7
A fluidized bed reduction experiment was carried out at 6:00 17j'l at a temperature of 50° C., using a reducing gas of 2300 mmNrn'/H, and a composition of 0D=5%.

Experiments were conducted by causing the apparatus shown in FIG. 1 and the conventional apparatus to exhibit the states shown in FIGS. 2 and 3. During the experiment, the total accumulated amount of fine ore in the circulating fluidized bed reduction apparatus was kept constant at 1300 kg in 3 cases. After the start of the experiment, we supplied 4# of raw materials to 600 kl!
/H.

The first and second cyclones shown in FIGS. 1 to 3 had exactly the same specifications.

Table 1 shows the minimum particle size collected by the cyclone and the amount of uncollected ore discharged from the second cyclone outlet pipe 26.

Table 1 As is clear from Table 1, the ore yield was significantly improved.

[Effects of the invention According to the device of the present invention.

■Ore yield has improved significantly.

■It is now possible to collect even fine particles, and the reduction rate has improved by 20%.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow sheet of an embodiment of the present invention, and FIG. 3 is an explanatory diagram of a conventional device. l...Fluidized bed reduction furnace 2...Fluidization gas 3...Powdered ore 10.20...Cyclone 11.21...Storage tank 12.22...Raw material supply port ■3.23 ... Reduced ore discharge port 14.24 - ... Ore circulation path 15.25 ... Ore circulation amount control device 16.26 ... Cyclone outlet pipe 100 ... Circulating fluidized bed reduction device 2nd

Claims (1)

[Claims] 1 In a circulating fluidized bed reduction device equipped with a cyclone,
A plurality of cyclones are arranged in series in multiple stages in the exhaust gas line of the fluidized bed reduction furnace, and storage tanks connected below each cyclone each have an independent supply port for raw material ore and a supply port to the fluidized bed reduction furnace. What is claimed is: 1. A circulating fluidized bed reduction device characterized by having a circulation path and a discharge port for reduced ore.