Method for ironmaking by smelting reduction in stir-generated vortex

Abstract

A method for ironmaking by smelting reduction in a stir-generated vortex includes: (1) placing a pig iron in an induction furnace, and then heating the pig iron to a molten state to form a molten iron, and maintaining the molten iron to be greater than or equal to 1450° C.; (2) stirring a center of the molten iron to form a vortex with a height-to-diameter ratio of 0.5-2.5, and continuously performing stirring; (3) mixing and grinding on an iron-containing mineral, a reducing agent and a slag-forming agent in a mass ratio of 1:(0.1-0.15):(0.25-0.4) to obtain a powder mixture, spraying and blowing the powder mixture to a center of the vortex, performing a reduction reaction, and stopping the stirring after the molten iron and molten slags are obtained, wherein a waste gas is produced; and (4) discharging the molten iron and the molten slags respectively, and exhausting a treated waste gas.

Claims

1. A method for ironmaking by smelting reduction in a stir-generated vortex, comprising: (1) placing a pig iron in an induction furnace, heating the pig iron to a molten state to form a molten iron, and maintaining a temperature of the molten iron to be greater than or equal to 1,450° C., wherein an amount of the pig iron is 5-20 vol % of an induction furnace body; (2) stirring the molten iron to form a vortex with a height-to-diameter ratio of 0.5-2.5, and continuously performing stirring; (3) spraying and blowing a mixture of an iron-containing mineral, a reducing agent and a slag-forming agent to a center of the vortex to cause a reduction reaction, and stopping stirring after molten iron and molten slags are obtained and a waste gas is produced, wherein a mass ratio of the iron-containing mineral, the reducing agent, and the slag-forming agent is 1:(0.1-0.15):(0.25-0.4); and (4) discharging the molten iron and the molten slags respectively, and exhausting a treated waste gas.

2. The method according to claim 1, wherein in the step (1), the induction furnace comprises a slag discharge opening and a molten iron discharge opening; the molten iron discharge opening is formed in a lower part on one side of the induction furnace, and the slag discharge opening is formed in an upper part on the other side of the induction furnace; the induction furnace is provided with a stirring paddle, a stirring paddle lifting system, a powder spraying device, an air hood, a flue gas purifying system, a waste heat recovery system, and a washing tower, wherein the stirring paddle is arranged in the induction furnace, the stirring paddle lifting system is connected with the stirring paddle, the powder spraying device is arranged at a top on one side of the induction furnace, the air hood is arranged above the induction furnace, an inlet of the flue gas purifying system is connected with the air hood through a pipeline, an inlet of the waste heat recovery system is connected with an outlet of the flue gas purifying system through a pipeline, an inlet of the washing tower is connected with an outlet of the waste heat recovery system through a pipeline, an outlet of the washing tower communicates with atmosphere, and the stirring paddle lifting system is used for replacing the stirring paddle.

3. The method according to claim 2, wherein the stirring paddle is a graphite stirring paddle.

4. The method according to claim 2, wherein in the step (2), the stirring paddle is inserted to ⅓-½ of a liquid level of the molten iron for a center stirring with a center stirring speed of 50-200 r/min.

5. The method according to claim 1, wherein in the step (3), the iron-containing mineral, the reducing agent and the slag-forming agent are mixed, ground, and then sprayed and blown to the center of the vortex through a powder spraying device.

6. The method according to claim 1, wherein in the step (3), the iron-containing mineral is iron ore, the reducing agent is pulverized coal, and the slag-forming agent is calcium oxide.

7. The method according to claim 1, wherein in the step (3), a reduction rate of the iron-containing mineral is greater than or equal to 95.5%, and an iron content in the molten slags is less than or equal to 0.35% by mass.

8. The method according to claim 2, wherein in the step (4), the molten slags are placed in an upper layer and the molten iron is placed in a lower layer in the induction furnace, wherein the molten slags are discharged from the slag discharge opening and the molten iron is discharged from the molten iron discharge opening.

9. The method according to claim 2, wherein the step (4), the waste gas is conveyed to the flue gas purifying system via the air hood for purification, a waste heat is then recovered through the waste heat recovery system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The sole FIGURE shows a schematically structural diagram of the induction furnace system of the present invention, wherein: 1 indicates slag discharge opening, 2 indicates molten iron discharge opening, 3 indicates graphite stirring paddle, 4 indicates stirring paddle lifting system, 5 indicates powder spraying device, 6 indicates air hood, 7 indicates flue gas purifying system, 8 indicates waste heat recovery system, 9 indicates washing tower.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(2) The present invention will be further detailed below in combination with embodiments.

Embodiment 1

(3) The structural diagram of the induction furnace system of the embodiment refers to the sole FIGURE.

(4) The method for ironmaking by smelting reduction in a stir-generated vortex comprises the following steps:

(5) (1) Placing a pig iron in an induction furnace, heating the pig iron to a molten state to form a molten iron, and maintaining a temperature of the molten iron to be greater than or equal to 1,450° C. for providing heating environment, wherein an amount of the pig iron is 5 vol % of an induction furnace body;

(6) (2) Inserting a graphite stirring paddle 3 to ⅓ of a liquid level of the molten iron for a center stirring at a stirring speed of 50 r/min, so that a vortex with a height-to-diameter ratio of 0.5 is formed, and the stirring is continued;

(7) Replacing the stirring paddle 3 through a stirring paddle lifting system 4 according to a degree of wear of the graphite stirring paddle 3, and smashing the worn graphite stirring paddle 3 for reuse as a reducing agent;

(8) (3) Performing mixing and grinding on an iron ore, a pulverized coal and a calcium oxide in a mass ratio of the iron ore to the pulverized coal to the calcium oxide being 1:0.1:0.25 to obtain a powder mixture, spraying and blowing the power mixture to a center of the vortex, performing a reduction reaction, and stopping the stirring after the molten iron and molten slags are obtained, wherein a waste gas is produced;

(9) (4) In the induction furnace, placing the molten iron in a lower layer and the molten slags in an upper layer, wherein the molten slags mainly comprise CaO, SiO.sub.2 and Al.sub.2O.sub.3; discharging the lower-layer molten iron through a molten iron discharging opening 2, and discharging the upper-layer molten slags through a slag discharging opening 1, wherein a reduction rate of the iron ore is 96.5%, and the molten slags contain 0.3% of iron; conveying the waste gas produced during the reaction to a flue gas purifying system 7 via an air hood 6 for purification, then recovering waste heat through a waste heat recovery system 8, absorbing harmful gas in the waste gas through a washing tower 9, and discharging a resultant gas into an atmosphere once relevant emission requirements are met.

Embodiment 2

(10) The structural diagram of the induction furnace system of the embodiment refers to the sole FIGURE.

(11) The method for ironmaking by smelting reduction in a stir-generated vortex comprises the following steps:

(12) (1) Placing a pig iron in an induction furnace, heating the pig iron to a molten state to form a molten iron, and maintaining a temperature of the molten iron to be greater than or equal to 1,550° C. for providing heating environment, wherein an amount of the pig iron is 15 vol % of an induction furnace body;

(13) (2) Inserting a graphite stirring paddle 3 to ½ of a liquid level of the molten iron for a center stirring at a stirring speed of 200 r/min, so that a vortex with a height-to-diameter ratio of 2.5 is formed, and the stirring is continued;

(14) Replacing the stirring paddle 3 through a stirring paddle lifting system 4 according to a degree of wear of the graphite stirring paddle 3;

(15) (3) Performing mixing and grinding on an iron ore, a pulverized coal and a calcium oxide in a mass ratio of the iron ore to the pulverized coal to the calcium oxide being 1:0.15:0.4 to obtain a powder mixture, spraying and blowing the power mixture to a center of the vortex, performing a reduction reaction, and stopping the stirring after the molten iron and molten slags are obtained, wherein a waste gas is produced; and

(16) (4) In the induction furnace, placing the molten iron in a lower layer and the molten slags in an upper layer, wherein the molten slags mainly comprise CaO, SiO.sub.2 and Al.sub.2O.sub.3; discharging the lower-layer molten iron through a molten iron discharging opening 2, and discharging the upper-layer molten slags through a slag discharging opening 1, wherein a reduction rate of the iron ore is 95.5%, and the molten slags contain 0.35% of iron; conveying the waste gas produced during the reaction to a flue gas purifying system 7 via an air hood 6 for purification, then recovering waste heat through a waste heat recovery system 8, absorbing harmful gas in the waste gas through a washing tower 9, and discharging a resultant gas into an atmosphere once relevant emission requirements are met.

Embodiment 3

(17) The structural diagram of the induction furnace system of the embodiment refers to the sole FIGURE.

(18) The method for ironmaking by smelting reduction in a stir-generated vortex comprises the following steps:

(19) (1) Placing a pig iron in an induction furnace, heating the pig iron to a molten state to form a molten iron, and maintaining a temperature of the molten iron to be greater than or equal to 1,500° C. for providing heating environment, wherein an amount of the pig iron is 20 vol % of an induction furnace body;

(20) (2) Inserting a graphite stirring paddle 3 to ½ of a liquid level of the molten iron for a center stirring at a stirring speed of 100 r/min, so that a vortex with a height-to-diameter ratio of 1.0 is formed, and the stirring is continued;

(21) Replacing the stirring paddle 3 through a stirring paddle lifting system 4 according to a degree of wear of the graphite stirring paddle 3;

(22) (3) Performing mixing and grinding on an iron ore, a pulverized coal and a calcium oxide in a mass ratio of the iron ore to the pulverized coal to the calcium oxide being 1:0.12:0.3 to obtain a powder mixture, spraying and blowing the power mixture to a center of the vortex, performing a reduction reaction, and stopping the stirring after the molten iron and molten slags are obtained, wherein a waste gas is produced; and

(23) (4) In the induction furnace, placing the molten iron in a lower layer and the molten slags in an upper layer, wherein the molten slags mainly comprise CaO, SiO.sub.2 and Al.sub.2O.sub.3; discharging the lower-layer molten iron through a molten iron discharging opening 2, and discharging the upper-layer molten slags through a slag discharging opening 1, wherein a reduction rate of the iron ore is 96.2%, and a molten slags contain 0.32% of iron; conveying the waste gas produced during the reaction to a flue gas purifying system 7 via an air hood 6 for purification, then recovering waste heat through a waste heat recovery system 8, absorbing harmful gas in the waste gas through a washing tower 9, and discharging a resultant gas into an atmosphere once relevant emission requirements are met.

Embodiment 4

(24) The structural diagram of the induction furnace system of the embodiment refers to the sole FIGURE.

(25) The method for ironmaking by smelting reduction in a stir-generated vortex comprises the following steps:

(26) (1) Placing a pig iron in an induction furnace, heating the pig iron to a molten state to form a molten iron, and maintaining a temperature of the molten iron to be greater than or equal to 1,480° C. for providing heating environment, wherein an amount of the pig iron is 10 vol % of an induction furnace body;

(27) (2) Inserting a graphite stirring paddle 3 to ⅓ of a liquid level of the molten iron for a center stirring at a stirring speed of 150 r/min, so that a vortex with a height-to-diameter ratio of 1.5 is formed, and the stirring is continued;

(28) Replacing the stirring paddle 3 through a stirring paddle lifting system 4 according to a degree of wear of the graphite stirring paddle 3;

(29) (3) Performing mixing and grinding on an iron ore, a pulverized coal and a calcium oxide in a mass ratio of the iron ore to the pulverized coal to the calcium oxide being 1:0.14:0.35 to obtain a powder mixture, spraying and blowing the power mixture to a center of the vortex, performing a reduction reaction, and stopping the stirring after the molten iron and molten slags are obtained, wherein a waste gas is produced; and

(30) (4) In the induction furnace, placing the molten iron in a lower layer and the molten slags in an upper layer, wherein the molten slags mainly comprise CaO, SiO.sub.2 and Al.sub.2O.sub.3; discharging the lower-layer molten iron through a molten iron discharging opening 2, and discharging the upper-layer molten slags through a slag discharging opening 1, wherein a reduction rate of the iron ore is 95.8%, and a molten slags contain 0.33% of iron; conveying the waste gas produced during the reaction to a flue gas purifying system 7 via an air hood 6 for purification, then recovering waste heat through a waste heat recovery system 8, absorbing harmful gas in the waste gas through a washing tower 9, and discharging a resultant gas into an atmosphere once relevant emission requirements are met.