Straight barrel type vacuum refining device and method for use the same

Abstract

Provided is a straight barrel type vacuum refining device comprising a vacuum chamber and a snorkel; during the vacuum refining the snorkel is inserted into the molten steel of the steel ladle, it is characterized in that, disposing a circulating tube being on the circumference of said snorkel, and blowing argon gas into the snorkel through the nozzles on an inner wall of a circulating tube; said circulating tubes are disposed in layers, the nozzles on the circulating tubes in the same layer are individually controlled as 2-6 in one group; disposing an eccentric gas permeable brick at the bottom of said steel ladle, and blowing argon gas into the steel ladle through the eccentric gas permeable brick, driving a circulating flow molten steel between the steel ladle and the vacuum chamber by using different blowing flow rate combinations of a steel ladle bottom blowing and each individually controlled unit of the circulating tube blowing system.

Claims

1. A method of operating a vacuum refining device, wherein the vacuum refining device comprises: a vacuum chamber; a snorkel connected to the vacuum chamber, wherein the snorkel is tubular in shape; a steel ladle adapted to hold molten steel during vacuum refining, wherein the snorkel is adapted to be inserted into the molten steel in a steel ladle during vacuum refining; a first circulating tube disposed about an inner circumference of said snorkel and adapted to blow a first argon gas into the molten steel through a plurality of nozzles disposed thereon, wherein a flow rate of the first argon gas in each of the plurality of nozzles on the circulating tube is individually controllable, a gas permeable brick eccentrically placed in a bottom of the steel ladle, wherein, during vacuum refining, a second argon gas blows into the steel ladle through the gas permeable brick to circulate the molten steel between the steel ladle and the vacuum chamber, the method comprising: inserting the snorkel into the molten steel in the steel ladle; blowing a first argon gas into the molten steel through the circulating tubes through the plurality of nozzles disposed thereon; blowing a second argon gas into the molten steel through the gas permeable brick in the bottom of the steel ladle, wherein, during decarburization, the blowing through the gas permeable brick and the blowing through the circulating tubes on the same side as the gas permeable brick is strong blowing, the blowing through circulating tube on the other side is weak blowing; during desulfurization, the bottom blowing through the gas permeable brick is strong blowing, and the blowing through circulating tube around the snorkel is weak blowing; and after decarburization and desulfurization, lowering the flow rate of the first argon gas through the circulating tubes and the flow rate of the second argon gas through the gas permeable brick.

2. A method of operating a vacuum refining device, wherein the vacuum refining device comprises: a vacuum chamber; a snorkel connected to the vacuum chamber, wherein the snorkel is tubular in shape; a steel ladle adapted to hold molten steel during vacuum refining, wherein the snorkel is adapted to be inserted into the molten steel in a steel ladle during vacuum refining; a first circulating tube disposed about an inner circumference of said snorkel and adapted to blow a first argon gas into the molten steel through a plurality of nozzles disposed thereon, wherein a flow rate of the first argon gas in each of the plurality of nozzles on the circulating tube is individually controllable, a gas permeable brick eccentrically placed in a bottom of the steel ladle, wherein, during vacuum refining, a second argon gas blows into the steel ladle through the gas permeable brick to circulate the molten steel between the steel ladle and the vacuum chamber, the method comprising: (1) decarburizing the molten steel by blowing a larger flow rate of the first gas through a first semicircle among two semicircles forming each circulating tube and a smaller flow rate of the first gas through the second semicircle among the two semicircles forming each circulating tube to circulate the molten steel in the steel ladle so that slags on a surface of the molten steel concentrated in one area on a surface of the molten steel; (2) desulfurizing the molten steel by blowing the first gas through all the nozzles in the circulating tube so that the slags are mixed with the molten steel under vacuum; and (3) increasing the flow rate of the first argon gas through the first semicircle and reducing the flow rate of the first argon gas through the second semicircle.

3. The method according to claim 1, wherein, in the vacuum refining device, a distance between an outer diameter of said snorkel and an inner diameter of said steel ladle is 100 mm-400 mm.

4. The method according to claim 1, wherein, in the vacuum refining device, a cross section of the outer wall of the snorkel consists of a longer circular arc and a shorter circular arc connected together, wherein the longer circular has a radius that is the same as a radius of the vacuum chamber, and the shorter circular arc has a radius that is greater than the radius of vacuum chamber.

5. The method according to claim 2, wherein, in the vacuum refining device, a distance between an outer diameter of said snorkel and an inner diameter of said steel ladle is 100 mm-400 mm.

6. The method according to claim 2, wherein, in the vacuum refining device, a cross section of the outer wall of the snorkel consists of a longer circular arc and a shorter circular arc connected together, wherein the longer circular has a radius that is the same as a radius of the vacuum chamber, and the shorter circular arc has a radius that is greater than the radius of vacuum chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will be explained below in detail in conjunction with the attached drawings:

(2) FIG. 1 is a structural schematic diagram of a straight barrel type vacuum refining device;

(3) FIG. 2 is an A-A cross-sectional view of FIG. 1;

(4) FIG. 3 is a B-B cross-sectional view of FIG. 1;

(5) In FIG. 1, 1—top lance, 2—vacuum extraction system, 4—feeding device, 5—vacuum chamber, 6—connecting flange, 7—snorkel, 8—circulating tube, 9—steel ladle, 10—eccentric bottom blowing argon gas permeable brick of the steel ladle, 11—steel ladle vehicle; 101—an imaginary center line that passes horizontally through the center of the straight barrel type vacuum refining device

(6) In FIG. 2: 13—snorkel large circular arc face, 15—snorkel small circular arc face; 102—an imaginary center line that passes horizontally through the center of the A-A cross-sectional view; 103—an imaginary center line that passes vertically through the center of the A-A cross-sectional view;

(7) In FIG. 3: 12—temperature measuring sampling point of the steel ladle; 104—an imaginary center line that passes horizonatally through the center of the B-B cross-sectional view; 105—an imaginary center line that passes vertically through the center of the B-B cross-sectional view.

DETAILED DESCRIPTION OF EMBODIMENTS

EXAMPLE 1

(8) As can be seen in FIG. 1, FIG. 2, and FIG. 3, the straight barrel type vacuum refining device mainly consists of a vacuum chamber 5, a snorkel 7, a steel ladle 9 and a steel ladle vehicle 11, the vacuum chamber and snorkel was connected by a flange 6, the snorkel was located directly above the steel ladle, the steel ladle was place on the steel ladle vehicle. A circulating tube 8 is disposed around the snorkel, and it may be used in blowing a inert gas into the molten steel to achieve multiple functions, the circulating tube was located in the upper part of the snorkel, and one layer of circulating tube were disposed in a direction perpendicular to the snorkel, the nozzles on the circulating tube were distributes at equal central angle, the central angle between the nozzles was 10°-30°; or, the nozzles on the circulating tube were distributed at equal distance, the number of the nozzles was 8-30. A bottom gas permeable brick 10 was disposed at the eccentric position of the steel ladle bottom, and argon gas entered into the molten steel through the gas permeable brick. During the molten steel refining, the steel ladle 9 was lifted to above the steel ladle vehicle 11, the steel ladle vehicle traveled to a processing working position, and the steel ladle was jacked to allow the snorkel 7 to be inserted into the molten steel, and vacuum extraction system 2 was activated to conduct a vacuum pumping, and argon gas was blown from the gas permeable brick 10, meanwhile the circulating tube 8 was activated to blow argon gas into the molten steel, and the flow rate and the pressure of the blown argon gas were adjusted as required, and the temperature measuring sampling mechanism 12 conducted a temperature measuring and sampling operation, when the composition and the temperature met the requirements, the vacuum was damaged, and the steel ladle was lowered to its original position, and the vacuum treatment refining process was finished.

EXAMPLE 2

(9) As can be seen in FIG. 1, FIG. 2, and FIG. 3, the straight barrel type vacuum refining device mainly consisted of the vacuum chamber 5, the snorkel 7, the steel ladle 9 and the steel ladle vehicle 11, the vacuum chamber and the snorkel are connected by the flange 6, the snorkel was located directly above the steel ladle, and the steel ladle was placed on the steel ladle vehicle. The feeding device 4 was disposed in the upper part of the vacuum chamber and it may add material, the vacuum pumping system 2 was responsible for the vacuum pumping, and the top lance 1 can blow oxygen. The circulating tube 8 was disposed around the snorkel, and it was used in blowing the inert gas into the molten steel to achieve multiple functions, the circulating tube was located in the upper part of the snorkel, in order to improve the deoxidation and desulfurization efficiency, two layers of circulating tubes were disposed in the direction perpendicular to the snorkel, the nozzles on each circulating tube were distributed at equal distance, the number of the nozzles in each layer was 6-15, and the nozzles in upper and lower layers were cross arranged. Three layers of the circulating tubes may also be disposed in the direction perpendicular to the snorkel, the nozzles on each of circulating tube were distributed at equal distance, the number of the nozzles in each layer was 6-12, the nozzles in adjacent layers were cross arranged; each layers were distributed at equal distance, and the distance was 150 mm-400 mm. The distance from the lowest layer of said circulating tube to the bottom of the snorkel was 100 mm-500 mm. The bottom gas permeable brick 10 was disposed at an eccentric position in the steel ladle bottom, and argon gas entered into the molten steel through the gas permeable brick.

(10) During molten steel refining, the steel ladle 9 was lifted to above the steel ladle vehicle 11, the steel ladle vehicle traveled to the working position, the steel ladle was jacked to allow the snorkel 7 to be inserted into the molten steel, and the vacuum extraction system 2 was opened to conduct the vacuum pumping, and argon gas was blown into from the gas permeable brick 10, meanwhile the argon gas was blown into the molten steel by the circulating tube 8, and the flow rate and the pressure of the blown argon gas was adjusted as required, the temperature measuring and sampling mechanism 12 conducted the temperature measuring and sampling operation, in the refining process, the required alloy or residue was added by the feeding device 4 according to the steel type requirement, when the composition and the temperature met the requirements, the vacuum was damaged, and the steel ladle was lowered to the original position, and the vacuum treatment refining process was finished.

EXAMPLE 3

(11) The other structures of the refining device was the same as Example 1 and 2, in order to further improve the decarburization efficiency, the nozzles as 2-6 in one group on the circulating tube were individually controlled.

(12) During the molten steel refining, the steel ladle 9 was lifted to above the steel ladle vehicle 11, the steel ladle vehicle traveled to the working position, and the steel ladle was jacked to allow the snorkel 7 to be inserted into the molten steel, and the vacuum extraction system 2 was activated to conduct vacuum pumping, and argon gas was blown into from the gas permeable brick 10, meanwhile the circulating tube 8 was activated to blow argon gas into the molten steel, the flow rate and the pressure of the blown argon gas was adjusted as required, during decarburization the bottom blowing and the circulating tube on the same side as the bottom blowing were strong blowing, the circulating tube on the other side was weak blowing; during desulfurization, the bottom blowing was strong blowing, the circulating tube around the snorkel were all weak blowing; the temperature measuring and sampling mechanism 12 conducted the temperature measuring and sampling operation, in the refining process the required alloy or residue were fed in by the feeding device 4 according to the steel type requirement, when the composition and the temperature reached the requirements, the vacuum was damaged, and the steel ladle was lowered to its original position, the vacuum treatment refining process was finished.

EXAMPLE 4

(13) The other structures of the refining device was the same as Example 1 or 2 or 3, in order to facilitate the temperature measuring and sampling operation in the refining process, the cross-sectional shape of said snorkel was roughly circular, it consisted of the large circular arc 13 (arc EFC) and the small circular arc 15 (arc EDC), the radius R1 of the large circular arc was the same as the vacuum chamber, the radius R2 of the small circular arc was greater than the vacuum chamber, the ratio of the radius of the large circular arc and the small circular arc was 1:1-00. The ratio of the distance r from the gas permeable brick 10 to the large circular arc 13 with the radius R1 of the large circular arc was 0.2-0.7.

(14) During molten steel refining, the steel ladle 9 was lifted to above the steel ladle vehicle 11, the steel ladle vehicle traveled to the processing working position, and the steel ladle was jacked to allow the snorkel 7 to be inserted into the molten steel, and the vacuum extraction system 2 was activated to conduct the vacuum pumping, and argon gas was blown from the gas permeable brick 10, meanwhile the circulating tube 8 was activated and argon gas was blown into the molten steel, the flow rate and the pressure of the blown argon gas were adjusted as required, during decarburization, the bottom blowing and the circulating tube on the same side of the bottom blowing were strong blowing, and the circulating tube on the other side was weak blowing; during desulfurization, the bottom blowing was strong blowing, and the circulating tubes around the snorkel were all weak blowing; the temperature measuring and sampling mechanism 12 conducted the temperature measuring and sampling operation, in the refining process the required alloy or residue was added by the feeding device 4 according to the steel type requirement, when the composition and the temperature met the requirements, the vacuum was damaged, and the steel ladle was lowered to its original position, and the vacuum treatment refining process was finished.

EXAMPLE 5

(15) The refining method at the time of the eccentric gas permeable brick in the steel ladle bottom was clogged or the steel ladle bottom blowing was closed according to the smelting requirement:

(16) (1) during molten steel refining, the steel ladle 9 was lifted to above the steel ladle vehicle 11, and the steel ladle vehicle traveled to the processing working position of the straight barrel type vacuum refining device, the blowing quantity of the snorkel and the circulating tubes individually controlled in 3 groups in the semi-circumference regions on the same side as the steel ladle bottom blowing were same, the total blowing flow rate was controlled to ton steel 13 NL/min, the blowing quantity of the flow rate individually controlled circulating tubes in 3 groups in the semi-circular region on the opposite side were the same, the total blowing flow rate of the circulating tubes was controlled to ton steel 7 NL/min;

(17) (2) the snorkel was inserted into the molten steel, and the snorkel was inserted for depth of 400 mm, meanwhile the vacuum pumping made the vacuum degree after 3 minutes to be reduced for 73 Pa. The vacuum chamber molten steel face top slag was observed by a vacuum chamber photograph, and the total blowing flow rate of the circulating tubes on the same side as the steel ladle bottom blowing on the snorkel was further adjusted to ton steel 18 NL/min;

(18) (3) after 10 minutes of the decarburization, the blowing quantity of all the flow rate individually controlled circulating tubes on the snorkel were all adjusted to the same, the total flow rate was controlled to ton steel 28 Nl/min;

(19) (4) after 15 minutes of the decarburization, a deoxidizer of aluminum particle was added at 2.4 kg/t steel by the feeding device 4, after 3 minutes, an oxygen determination was conducted at the sampling position 12, the active oxygen of the molten steel was 0.32 ppm. A lime of 6.08 kg/t steel was blown by the lance;

(20) (5) after 6 minutes of blowing of the lime, the blowing flow rate of the circulating tube on the snorkel was adjusted to small, the blowing quantity of the flow rate individually controlled circulating tubes in 3 groups in semi-circumference region on the same side of the steel ladle bottom blowing were same, the total blowing flow rate was adjusted to ton steel 15 NL/min, the blowing quantity of the flow rate individually controlled circulating tubes in 3 groups in the semi-circumference region on the opposite side were the same, the total blowing flow rate of the circulating tubes was adjusted to ton steel 5 NL/min, after 6 minutes of circle the molten steel, the steel ladle bottom blowing was closed, the vacuum was damage, and the sampling and temperature measuring was conducted at the sampling position 12.

(21) Implementation Effect:

(22) In a certain steel plant, a combination blowing refining test of 86 furnaces steel ladle bottom blowing and the circulating tube on the snorkel as well as 23 furnaces snorkel circulating tube blowing refining test, and the test results were as follow.

(23) The combination test results of 86 furnaced steel ladle steel ladle bottom blowing and the circulating tube on the snorkel were: the active oxygen of the starting molten steel before entering into the straight barrel type vacuum refining device (a[O]) was between 0.0459-0.0823%, the average was 0.0589%, the [C] was between 0.025-0.050%, the average was 0.032%, the [S] was between 0.004-0.009%, the average was 0.0069%, in the 30-45 minutes (the average was 39 minutes) of refining cycle of the straight barrel type vacuum refining device, the ton steel lime addition quantity was 3-8 kg/t−1, the average was 5.32 kg/t−1, the ton steel aluminum particle feed quantity was 0.8-3.1 kg/t−1, the average was 1.78 kg/t−1, the molten steel [C] at endpoint of the vacuum refining was between 0.0005-0.0011%, the average was 0.0008%; the molten steel [S] content was 0.0008-0.0021%, the average was 0.0013%, the desulfurization rate was 73-87%, the average desulfurization rate reached to 81.1%.

(24) The circulating tube blowing test results of 23 furnaces on the snorkel were: the starting active oxygen (a[O]) in the molten steel before entering the straight barrel type vacuum refining device was between 0.0572-0.0792%, the average was 0.0578%, the [C] was between 0.023-0.048%, the average was 0.031%, the [S] was between 0.005-0.008%, the average was 0.0062%, during 30-45 minutes (the average was 42 minutes) of the refining circle of the straight barrel type vacuum refining device, ton steel lime addition quantity was 3-8 kg/t−1, the average was 5.64 kg/t−1, the ton steel aluminum particle addition quantity being 1.1-3.2 kg/t−1, the average was 1.92 kg/t−1, the molten steel [C] at endpoint of the vacuum refining was between 0.0007-0.0013%, the average was 0.0009%; the molten steel [S] content was 0.0007-0.0025%, the average was 0.0014%, the desulfurization rate was 69-82%, the average desulfurization rate reached to 75.2%.