JPH062894B2 - Method for producing molten metal from powdered ore - Google Patents

Description

The present invention relates to a method for producing molten metal from powdered ore containing a metal oxide.

[Conventional technology]

Iron ore and other metal ore resources are made up of powdered ores, and the proportion of powdered ores tends to increase in the future. Especially, in order to improve the quality of low-grade ores, flotation, magnetic separation, etc. are conducted, and it is expected that the ratio of fine ore will increase. The method of agglomerating powdered ore and then reducing it to obtain molten metal requires the cost for agglomeration, so it is necessary to reduce the powdered ore without agglomeration using a fluidized bed. Methods and devices for doing so have been developed.

The inventors of the present invention previously mentioned in Japanese Patent Application No. 60-193914 maintain a packed bed of a carbon-based solid reducing agent and a fluidized bed of the carbon-based solid reducing agent above it in a vertical reduction furnace, and use powdered ore as oxygen. We proposed a method for producing molten metal by charging a fluidized bed with a gas containing it and blowing an oxygen-containing gas into a packed bed of a carbon-based solid reducing agent to smelt and reduce powdery ore.

In such a technique, (1) conventionally, the actual gas flow rate in the furnace is calculated from the furnace temperature, pressure, gas flow rate, and other in-furnace conditions during operation, and the terminal velocity U _t (particles outside the system is calculated. The carbon-based solid reducing agent having a particle size equal to or larger than n times the gas flow rate) was charged into the furnace. The fraction below the particle size under the sieve was unused.

(2) The generated or obtained carbon-based solid reducing agent was charged in the furnace in its entirety including fine powder. Therefore, the fine powder is scattered along with the exhaust gas, and it is difficult to effectively utilize the sensible heat of the fine powder.

[Problems to be solved by the invention]

INDUSTRIAL APPLICABILITY The present invention relates to a process for smelting and reducing powdery ores with a carbon-based solid reducing agent and an oxygen-containing gas using a vertical reduction furnace without agglomerating powdery ores containing metal oxides. The purpose of the present invention is to increase the use particle size range of the solid reducing agent and improve the yield of use of the carbon-based solid reducing agent.

In addition, the amount of each of the coarse-grained carbon-based solid reducing agent staying in the packed bed and the fine-grained carbon-based solid reducing agent staying in the fluidized bed, and the char generated in the coal carbonization furnace and the carbonaceous material generated in the previous process It is necessary to operate with a balanced particle size distribution.

[Means for solving problems]

The present invention maintains a packed bed of a carbon-based solid reducing agent and a fluidized bed of the carbon-based solid reducing agent above it in a vertical reduction furnace, and an oxygen-containing gas is supplied from tuyere provided at a plurality of circumferential positions. In a packed bed of a carbon-based solid reducing agent, and a powdered ore containing a metal oxide is charged together with an oxygen-containing gas in a fluidized bed, and is melted and reduced. The carbon-based solid reducing agent to be introduced is twice the diameter equivalent to the terminal velocity calculated from the temperature, pressure, gas flow rate, apparent density of solid (carbon-based solid reducing agent), gas density, and viscosity coefficient from the furnace top. The carbon-based solid reducing agent having the above particle diameter is mixed, and the carbon-based solid reducing agent having a particle diameter less than twice the terminal velocity equivalent diameter is distributed in the particle diameter distribution of the carbon-based solid reducing agent charged from the furnace top. Depending on the situation, it may be necessary to distribute and charge into a packed bed of solid reducing agent such as a fluidized bed of solid reducing agent. To.

[Action]

In the present invention, among the carbon-based solid reducing agents, a carbon-based solid reducing agent having a particle diameter of twice or more the diameter equivalent to the terminal velocity U _{t is} charged from the furnace top of the smelting reduction furnace and the carbon charged from this furnace top. Depending on the particle size distribution of the carbon-based solid reducing agent, less than twice the equivalent diameter of carbon-based solid reducing agent is blown into powdered ore (upper tuyere) or carbon-based solid reducing agent packed bed blowing tuyere (lower tuyere ). In addition to this blowing, the distribution of the respective blowing amounts from the lower tuyeres is determined by the particle size of the carbon-based solid reducing agent charged from the furnace top.

The fine carbonaceous solid reducing agent blown into the packed bed from the blowing tuyere is burned by oxygen, and the amount of the coarse-grained carbon solid reducing agent burned is reduced by the oxygen content consumed in the burning.

The carbon-based solid reducing agent blown from the powdered ore blowing tuyere is burned by oxygen to become high-temperature particles, and the ore blown together is melted and deposited on the surface of the blown carbon-based solid reducing agent. Is promoted, the carbon-based solid reducing agent is effectively used, and the carbon-based solid reducing agent basic unit is improved.

By injecting the fine carbon solid reducing agent from the upper and lower tuyeres in this way, the carbon solid reducing agent that has conventionally been scattered from the fluidized bed and the carbon that was not appropriate to be charged from above -Based solid reducing agent can be effectively used, and the carbon-based solid reducing agent can be filled by increasing or decreasing the fine powder carbon-based solid reducing agent blown into the lower tuyeres according to the powder size distribution of the coarse-grained carbon-based solid reducing agent. The descent rate of the bed can be adjusted, and the bed height of the packed bed can be easily controlled within an appropriate range.
A stable operation of the furnace can be performed.

The terminal velocity equivalent diameter can be calculated from Allen's equation and Newton's equation using temperature, pressure, gas flow velocity, apparent density of solid (carbon-based solid reducing agent), gas density, and viscosity coefficient.

〔Example〕

The method of the present invention was carried out using the smelting reduction system shown in FIG.

A carbon-based solid reducing agent is supplied from the carbon-based solid reducing agent pretreatment furnace 14 to the smelting reduction furnace 6 to form a packed bed 4 and a fluidized bed 5 in the reduction furnace 6. The oxygen-containing gas 2 is blown into the packed bed 4 from the lower tuyere 3 of the reduction furnace 6, and the solid reducing agent in the packed bed 4 is burned by this gas. Acts as a fluidizing gas that forms The fluidized bed 5 is charged with the powdery ore that has been fluidized and pre-reduced in the ore pretreatment furnace 16 from the powdery ore loading port (upper tuyeres) 8. This ore is melted in the fluidized bed and dropped into the furnace bottom through the packed bed 4, and is melted and reduced in the dropping process to become molten metal 10 and molten slag 11 which are accumulated in the furnace bottom and discharged from the tap hole 12 Is discharged.

The exhaust gas 13 discharged from the smelting reduction furnace 6 is used as a reducing gas in the ore pretreatment 16 and as a carbonization gas in the carbon-based solid reducing agent pretreatment furnace 14.

In the above system, the embodiment separates the carbon-based solid reducing agent discharged from the carbon-based solid reducing agent pretreatment furnace into coarse particles and fine particles, and the coarse particles 15 are inserted into the furnace from above the reducing furnace 6. However, the fine particles 15a are separated from the coarse particles by the upper tuyeres 8 and the lower tuyeres 3.
Blown in from.

The amount of fine carbonaceous solid reducing agent blown from each of the upper tuyeres 8 and the lower tuyeres 3 is determined according to the particle size distribution of the coarse-grained carbonaceous solid reducing agent 15 and is blown.

The results of the production of molten metal according to the present invention in a reducing furnace having a furnace diameter of 1.2 m are shown below.

Example 1 1) Powdered iron ore Brand: MBR-PB Particle size: Mainly 150 mesh or less 2) Carbon solid reducing agent to be supplied Type: Blast furnace coke Particle size: Particle size distribution 20 to 10 mm 34% 10 to 5 mm 27 % 5 to 1 mm 24% -1 mm 15% (Terminal velocity equivalent diameter 0.5 mm) Furnace top charging 20 to 1 mm Tuyere blowing less than 1 mm Supply: 1040 kg / H Fluidized bed blowing: 95 kg / H (Full charging 9.1% of the amount) Packed bed injection: 61 kg / H (5.9% of the total charge) 3) Pig iron production: 11.8 t / day Example 2 1) Powdered iron ore Brand: MBR-PB Particle size: Mainly 150 mesh or less 2) Supplying carbon solid reducing agent Type: Blast furnace coke Particle size: Particle size distribution 20-10mm 28% 10-5mm 28% 5-1mm 25% -1mm 19% (corresponding to terminal speed) Diameter 0.5mm) Furnace top charging 20 to 1mm Tuyere blowing less than 1mm Supply amount 997 kg / H Fluidized bed injection: 78 kg / H (7.8% of total charge) Packed bed injection: 111 kg / H (11.1% of total charge) (compared to Example 1, Since the amount of coarse particles was small, the charging rate of the packed bed was high.) 3) Pig iron production rate: 11.2 t / day The smelting reduction furnace could be stably operated by operating under the above operating conditions.

〔The invention's effect〕

As described above, the present invention has the following excellent effects.

a) Conventionally, fine-grained or fine-powder carbon-based solid reducing agents have been used in different processes, but the present invention makes it possible to use them in the same process, and the bed height of the packed bed fluidized bed can be easily controlled and the carbon-based solid reducing agents are easily It has become possible to reduce the basic unit.

b) In the dust treatment of the exhaust gas of the smelting reduction furnace, the amount of scattered carbon-based solid reducing agent generated was reduced, and the treatment man-hour was reduced.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a vertical reduction furnace to which the method of the present invention is applied. DESCRIPTION OF SYMBOLS 1 ... Powdered ore 2 ... Gas containing oxygen 3,8 ... Tuyere 4 ... Packing layer of carbon-based solid reducing agent 5 ... Fluidized bed of carbon-based solid reducing agent 6 ... Vertical melting and reducing furnace 10 ... Molten metal 11 ... Molten slag 12 ... Detaching mouth

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Ushijima 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Technical Research Headquarters (72) Inventor Hideyuki Momokawa 1 Kawasaki-cho, Chiba-shi Kawasaki Steel Co., Ltd. Chiba (56) References JP 61-221315 (JP, A) JP 59-133307 (JP, A) JP 62-56537 (JP, A) JP 62-227018 (JP, A) )

Claims (1)

[Claims] 1. A vertical reduction furnace is provided with a packed bed of carbon-based solid reducing agent and a fluidized bed of carbon-based solid reducing agent above it, and contains oxygen from tuyere provided at a plurality of circumferential positions. A gas is blown into a packed bed of a carbon-based solid reducing agent, and a powdered ore containing a metal oxide is charged into a fluidized bed together with an oxygen-containing gas, and in a molten metal production method of smelting reduction, a vertical reduction furnace is used. The carbon-based solid reducing agent to be charged is divided into the one charged from the furnace top and the one charged from tuyere, and the one having a particle diameter of twice or more the diameter equivalent to the terminal velocity is charged from the furnace top. The carbon-based solid reducing agent having a particle size less than twice the terminal velocity equivalent diameter is filled with the fluidized bed of the solid reducing agent and the solid reducing agent according to the particle size distribution of the carbonaceous material charged from the furnace top. A method for producing molten metal from powdered ore, characterized in that the molten metal is distributed and charged into a bed.