JPH04301024A - Operation method for counter flow type powdery ore reduction furnace - Google Patents

Abstract

PURPOSE:To execute reduction of powdery ore at high efficiency by dropping powdery ore at a specific ratio into a vertical furnace heated at the specific temp. through dispersing mechanism in the furnace top and blowing reducing gas from lower part at a specific flow velocity. CONSTITUTION:The multi-hole plate type powdery ore dispersing device 1 is arranged at the top part in inner part of the vertical shaft type reaction furnace 2, and the powdery ore adjusting the particle size is dispersed and dropped into the reaction furnace 2 heated at 600-1000 deg.C in particle vol concn. of <=20% of the vol in the furnace. Then, the reducing gas from the lower of the furnace through an introducing hole 3 is blown and raised at gas flow velocity of end velocity or lower of the average particle size, and the dropped ore is discharged from a reduced ore discharging hole 6. Further, the exhaust gas through the top part in the reaction furnace 2 is introduced into a cyclone 4 and the collected powder is discharged from a discharging tube 7 and the exhaust gas is taken out from an introducing tube 8. By this method, the powdery ore is uniformly dispersed in the reaction chamber 2, and contact with the reducing gas is improved and reducing reaction at high efficiency is secured.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating an ore reduction furnace suitable for use as a pre-reduction furnace in the process of producing pig iron by melting and reducing pre-reduced powdered iron ore.

0002

[Prior Art] Conventionally, as a preliminary reduction furnace for reducing such powdery raw ore, for example, JP-A No. 63-1
As disclosed in Japanese Patent Publication No. 40018 and Japanese Patent Application Laid-Open No. 1-111807, powdered ore is introduced from the upper side of a riser forming a fluidized bed, and a carrier gas for forming a fluidized bed and a melting reduction furnace are introduced from the bottom. When the exhaust gas from the ore is introduced as a reducing gas to form a fluidized bed of ore and the ore is reduced by a solid-gas reaction, the particles and reaction gas that formed the fluidized bed are removed above the fluidized bed or through a cyclone. At the same time as collecting the powder, the powder is returned to the riser by lowering the downcomer, or by the circulating fluidized bed method, or by Japanese Patent Application Laid-Open No. 47-1631.
As described in Publication No. 2, there is a shaft-type furnace in which lump ore or agglomerated material is reduced in a moving bed.

0003

[Problems to be Solved by the Invention] However, in this conventional reduction furnace using a fluidized bed, it is necessary to form reaction layers in multiple stages in order to increase the effectiveness of gas utilization. The drawbacks are increased equipment costs and complicated operations.

[0004] In addition, in shaft type furnaces, it is necessary to pelletize the fine ore to be charged in order to prevent the ore from being pulverized in the furnace and hanging on the shelf due to sticking.
The disadvantage is that the raw material powder ore cannot be used as is, and the cost increases.

[0005] The problems to be solved by the present invention are as described above.
It overcomes the drawbacks of fluidized bed furnaces and shaft furnaces and allows powdered raw ore to be used directly without pre-treatment.
Moreover, the objective is to find a reducing furnace with high reaction efficiency for the reducing gas used and a method of using the same.

[0006]

[Means for Solving the Problems] The present invention employs a countercurrent reactor in which powdery ore is dropped in a dispersed state into a reaction space and a reducing gas is introduced into the falling ore from below to cause a reduction reaction. This problem was solved by a method of reducing powdered ore.

[0007] When using powdered iron ore of about 1 mm in this countercurrent type reactor, in order to carry out the reduction reaction efficiently, it is necessary to drop it uniformly into the reaction space.
To do this, a dispersion device such as a rotary blade or a perforated plate is placed at the top of the reaction space, the raw material is dropped from this dispersion device, and the volume concentration of the dropped powdery ore in the reaction space is maintained at 20% or less. do.

[0008] Furthermore, this reaction space is heated by external heat or by introducing a heated reducing gas.
The temperature is maintained at 00°C.

The residence time of the particles necessary for reduction is adjusted by making the flow rate of the injected reducing gas approach the terminal velocity of the particles, or by adjusting the height of the reaction chamber into which the particles fall.

0010

[Operation] A highly efficient reduction reaction is ensured by uniformly dispersing the fine ore in the reaction chamber and improving the contact between the reducing gas and the ore particles.

[0011] Furthermore, if the volumetric concentration of the dropped powdery ore in the reaction space exceeds 20%, it will be difficult to disperse the particles and they will tend to stick, so it is necessary to maintain the concentration below 20%. If the concentration is too low, the reaction efficiency of the gas will deteriorate, and if the concentration is high, it will be difficult to operate.
It is desirable that it be within the range of ~10%.

0012

[Embodiment] An example in which the present invention is applied to preliminary reduction of fine ore to be introduced into an iron ore smelting reduction furnace will be described.

FIG. 1 shows an overview of an apparatus embodying the present invention.

In the figure, reference numeral 1 indicates a perforated plate type fine ore dispersion device installed at the inner top of a shaft-type reactor 2 having an internal volume of 50 liters. Fine ore with an iron content of 64% and particle size adjusted to 1 mm or less is placed in reactor 2.
into the dispersion device 1 through the inlet 5 of the dispersion device 1.
The water was dispersed into the reactor 2 at a rate of 0.4 liters per minute. On the other hand, at 950℃, CO-70%, H2-30
% gas composition of the smelting reduction furnace was introduced from the reducing gas inlet 3 at a rate of 50 Nm3/hr, and the precipitated ore was discharged from the reduced ore outlet 6. The average reduction rate of the discharged ore was 62%, and the discharge amount was 85 kg/hr. Furthermore, the composition of the exhaust gas from the exhaust gas outlet pipe 8 which has passed through the top of the reactor 2 is CO-42%, H2-18%,
CO2 -28%, H2 O -12%, and the amount of fine powder collected by the cyclone 4 and discharged from the collected powder discharge pipe 7 was 3 kg/hr. Further, the exhaust gas temperature was 600°C.

[0015]

[Effects of the Invention] The present invention provides the following effects.

(1) Fine ore can be directly used for reduction treatment,
No special preliminary treatment of fine ore is required.

(2) A high level of gas utilization can be ensured by the single-column reduction furnace.

(3) Since the pressure loss in the reactor can be reduced, the energy consumption rate can be reduced. (4) Since the fine ore undergoes heat exchange in the reactor, the exhaust gas temperature can be lowered and the energy consumption rate can be lowered.

[Brief explanation of drawings]

FIG. 1 shows an outline of an apparatus in which the present invention is implemented as a preliminary reduction apparatus for a smelting reduction furnace.

[Explanation of symbols]

1. Powdered ore dispersion equipment 2 Reactor 3 Reducing gas inlet 4 Cyclone 5 Raw material ore input port 6 Reduced ore discharge port 7 Cyclone collected powder discharge pipe 8 Exhaust gas outlet pipe

Claims (1)

[Claims] Claim 1: The furnace has a vertically elongated internal shape, and a powder ore dispersion mechanism is provided at the top of the furnace.
In a furnace heated to 00 to 1000℃, 20
A method for operating a countercurrent type ore reduction furnace, in which the particles are dispersed and fallen at a volume concentration not exceeding 1.2%, and reducing gas is blown into the furnace from below at a gas flow rate lower than the terminal velocity of the average particle diameter.