JPS62230914A - Method for reducing powdery ore in fluidized bed - Google Patents

Abstract

PURPOSE:To increase the rate of utilization of a reducing gas and to improve the production efficiency by adding unsinterable particles which are mixed with powdery ore and fluidized to a fluidized bed so that the sintering of the ore is prevented even when the temp. of the reducing gas is raised. CONSTITUTION:Unsinterable particles and powdery ore are fed from an ore feeding hole 2 and a heated reducing gas from a reducing gas feeder 4 is fed from a part under a gas dispersion plate 3 to form a fluidized bed 1 contg. the unsinterable particles and the powdery ore. Particles jumping out of the bed 1 are captured with a circulation cyclone 6 and charged into a fluidized bed 7 for separating unsinterable particles. The separated unsinterable particles are circulated to the fluidized bed 1 through circulation holes 9, 10. The reduced powdery ore is discharged from a discharge hole 8.

Description

[Detailed description of the invention] [Industrial application field] The present invention is based on the flow of fine ore! ’Regarding the refund method.

This relates to a method of pre-reducing fine ore using a fluidized bed.

[Conventional technology]

Iron ore and other metal ore resources are increasingly composed of fine ore, and the proportion of fine ore is likely to increase in the future. Especially to improve the grade of low-grade ores.

The ratio of grain ore is expected to increase as ore beneficiation such as flotation and magnetic separation is carried out. The method of agglomerating fine ore and then reducing it to obtain molten metal requires the cost of agglomeration, so a method and device for reducing fine ore using a fluidized bed has been developed. ing.

In the fluidized reduction of fine ore, there is a problem that the fine ore tends to sinter, and to prevent this, it is necessary to lower the temperature of the reducing gas during operation, as lowering the temperature of the reducing gas slows down the reduction reaction rate. , gas utilization rate decreases, production efficiency also decreases, and product re-oxidation occurs.

[Problem that the invention seeks to solve]

The present invention prevents sintering of powdered ore in a fluidized bed,
The purpose is to advance the reduction reaction at as high a temperature as possible to increase the gas utilization rate, increase production efficiency, and increase the efficiency of the fluidized bed reduction method.

[Means for solving problems]

In order to achieve the above object, the present invention has taken the following technical means.

(a) A sintering prevention material is mixed into powdered ore and subjected to a reduction reaction in a fluidized bed. In this case, the sintering prevention material is a material that does not have sinterability and prevents the sintering of the powdered ore in the reducing reaction atmosphere of the powdered ore, and is fluidized together with the powdered ore. must be present between the particles.

(b) The reduced ore is taken out from the fluidized bed together with the sintering prevention material, and immediately after being taken out, the sintering prevention material is separated from the reduced ore and circulated into the fluidized bed.

This separation is carried out hot immediately after removal from the fluidized bed.
Prevent heat loss as much as possible.

Such non-sintering material particles include non-sintering refractories,
Ceramic powder can be used.

Separation of these and reduced ores at high temperatures can be carried out by fluidized bed separation, magnetic separation based on the presence or absence of magnetism, sieving separation based on particle size differences, and the like.

[Operation] Since non-sintering material particles that mix with the powdered ore and flow are interposed in the fluidized bed, the powdery ore does not sinter even if the reducing gas temperature is increased, thus reducing the reduction reaction rate. This improves the reducing gas utilization rate and improves production efficiency.

If the fluidization conditions in the fluidized bed are the same as those for fine ore, particles with different specific gravities can have different particle sizes.

Separation of reduced ore powder and non-sinterable material particles can be performed by fluidized bed separation or particle size separation using vibrating gray (W) for particles with different particle sizes and densities. By using non-sinterable material particles that do not have any sintering properties, they can be easily separated and circulated by magnetic separation.

In the case of fluidized bed separation, the minimum fluidization speed U f (T) tbed+ of the carbonaceous material or refractory material particles and the particle terminal velocity (velocity at which the particles fly out of the system) U t (bed) are fluidized. The geometric mean value Up(T)rbed) = (Umf(T)rbed+ +1U t(T)+
bed) ) "2 is adopted as a guideline for the fluidizing gas flow rate in the fluidized bed separation furnace.Then, the particle terminal velocity IJ t (T) (are) of the reduced fine ore is the carbon material forming the fluidized bed. and the average fluidization velocity U of refractory material particles
P(T)(bed> Adjust the particle size of the carbonaceous material or refractory material so that it is larger than the P(T)(bed> The non-sinterable substances separated at this high temperature can be returned directly to the fluidized bed reduction furnace and recycled.

In this case, high-temperature exhaust gas from a fluidized bed reduction furnace can be used as the fluidizing gas for the fluidized bed separation furnace.

〔Example〕

FIG. 1 illustrates an apparatus that can suitably carry out the method of the present invention. The fluidized bed 1 with an inner diameter of 80 mm has an ore supply port 2 for inserting non-adhesive substances and fine ore, and is equipped with a device 4.5 for producing high-temperature reducing gas. It is equipped with a circulation cyclone 6 for collection when circulating ore. Fine iron ore was reduced in such a circulating fluidized reduction furnace.

The operation begins by inserting a non-adhesive substance and fine ore into a circulating fluidized bed, and introducing high-temperature reducing gas from below the gas distribution plate 3 to create a stable circulating fluidized bed of the non-adhesive substance and fine ore. Let it form. At this time, a fluidized bed for separating non-sinterable material particles is operated, making it possible to separate the non-adhesive material and the reduced ore under high temperature conditions. is recycled and some is emitted as a product. In this case, 2
It may be discharged as a manufactured product.

Fine ore and non-adhesive substances should have particle sizes such that the terminal velocity of the particles is less than the gas flow rate of the reduction furnace.For example, the H2 gas amount of 3851/min in this example is 900°C.
It has a gas flow velocity of about 5 m/sec at 200 m/sec at that temperature.
The terminal velocity of mesh particles is about 50 cm/sec. In addition, the terminal velocity of alumina particles of 60 to 65 mesh is 4 m/Se C. Particles flying out from inside the furnace are collected by circulation cyclone 6,
Charged to a fluidized bed for separation of non-sinterable material particles.

The operating conditions and product return rate were as follows.

(A) Circulating fluidized bed reduction furnace Reaction tube diameter: Inner diameter 80mm Iron ore Brand: Brazilian MBR ore with particle size of 200 mesh or less Non-adhesive substance and particle size: Alumina 60-65 mesh Iron ore supply rate: 125 g/min Reducing gas composition: H2 100% Reducing gas amount: 3851/min Reduction furnace internal temperature: 900°C Gas usage rate: 15.9% (B) Fluidized bed reaction for separation of non-sinterable material particles Pipe diameter 2 inner diameter 80mm Fluidization gas: Exhaust gas H2 = 85% H20 = 15% Fluidization gas temperature = 800℃ Fluidization gas flow rate near 7/min Product reduction rate: 8
1.7% In this case, if no non-sintering material is added, the reaction temperature is 9.
At 00°C, sintering was severe and ore with an ore particle size of 200 mesh or less could not be reduced. Reduce the reduction temperature to 60
Fluid reduction was first possible at 0°C, but the gas utilization rate at that time was 7%.

〔Effect of the invention〕

The present invention has made it possible to perform fluidized bed reduction of powdered ore using high-temperature reducing gas, contributing to improved gas utilization and production efficiency.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an example of mounting used for carrying out the method of the present invention. 1... Fluidized bed 2... Stone supply port 3... Dispersion plate 4... Reducing gas supply device 5... Preheating device 6... Circulating cyclone 7... Non-sintering material particles Fluidized bed for separation 8... Reduced ore discharge port 9... Circulation port 10 for separated non-sintered material particles...
Kangen Seishin circulation port 11...exhaust gas

Claims (1)

[Claims] 1. In a fluidized bed reduction method for fine ore, supplying non-sinterable material particles at the fluidization reduction temperature of the ore into a fluidized bed,
A fluidized bed reduction method for powdery ore, characterized in that the material particles discharged together with the reduced ore are separated from the reduced ore and circulated in the fluidized bed immediately after being discharged.