Multiple chamber material-stirring lance and method

Abstract

A multiple chamber material-stirring lance and method used to treat molten metal in a ladle, the lance having a stirring gas chamber, and a plurality of gas permeable ports arranged at a terminal end of the gas chamber, and at least one material chamber positioned parallel to the gas chamber and terminating in a plurality of material ports. In use, the multiple chamber material-stirring lance is lowered into the ladle of molten metal, and gas and material are both introduced into a respective chamber and emitted through their respective ports. Stirring gas emitted through the gas permeable ports under a gas pressure between 40 and 600 cfm causes the stirring gas to create a boiling effect in the molten metal, drawing material into the stirring gas bubbles and away from the lance body, improving material dispersion efficiency and thus impurity extraction from the molten metal.

Claims

1. A multiple chamber material-stirring lance (40) for use in a hot metal desulfurization process performed in a mill having a motorized lance drive with a lance weight support capacity, a ladle having a bottom joined to a continuous side wall holding a predetermined quantity of hot metal, and a gas manifold supplying a gas supply, where the multiple chamber material-stirring lance is supported by the motorized lance drive in the predetermined quantity of hot metal in the ladle, the multiple chamber material-stirring lance comprising: a gas chamber (48) having a first end and a terminal end, and a length between the first end and the terminal end defining a chamber wall, the chamber wall further defining an interior space having an interior wall side facing the interior space and an opposed outer wall side; a gas connection pipe (44) at the first end coupled to the gas manifold and to the gas supply; at least one lower port (52) positioned into the chamber wall and leading out of the terminal end of the gas chamber (48) to an exterior of the multiple chamber material-stirring lance (40); a material chamber (43) having a first end and a second end, the first end connected to a material connection pipe (42) and the second end terminating in at least one material discharge port (60); a material chamber length between the first end and second end defining a material chamber wall, the material chamber wall having an exterior wall side; and a refractory coating (46) encasing both the opposed outer wall side of the gas chamber and the exterior wall side of the material chamber so as to form a single lance body; wherein the exterior wall side of the material chamber (43) is adjacent to the outer wall side of the gas chamber (48); wherein the at least one lower port (52) is a gas permeable structure having a body formed with an inlet at one end and an opposed outlet, the inlet secured to a through-hole formed into the chamber wall, and the opposed outlet positioned relative to the refractory coating so as to allow fluid communication between the interior space of the gas chamber and the predetermined quantity of hot metal immediately beyond the refractory coating, the opposed outlet having a diameter measurement between about 0.5 cm to about 13 cm; and wherein the at least one lower port is at least one of a pipe, a nozzle, a porous plug, and a directional plug.

2. The multiple chamber material-stirring lance (40) in claim 1, wherein the material chamber (43) terminates in a pipe having a pair of opposed material discharge ports (60), a terminal end of the material chamber and ports forming an inverted T-configuration.

3. The multiple chamber material-stirring lance (40) in claim 1, wherein the at least one material discharge port (60) is positioned at a lowermost terminal end of the material chamber.

4. The multiple chamber material-stirring lance (40) in claim 1, wherein the gas chamber (48) is further comprised of: at least one body port (50) positioned into the length of the gas chamber; and wherein the at least one body port is a gas permeable structure having a body formed with an inlet at one end and an opposed outlet, the body inlet secured to a through-hole formed into the chamber wall, and the opposed body outlet positioned relative to the refractory coating so as to allow fluid communication between the interior space of the gas chamber and the predetermined quantity of hot metal immediately beyond the refractory coating, the opposed body outlet having a diameter measurement between about 0.5 cm to about 13 cm; wherein the at least one body port is at least one of a pipe, a nozzle, a porous plug, and a direction plug; and wherein the at least one body port is positioned between the first end of the gas chamber and the at least one lower port.

5. The multiple chamber material-stirring lance (40) of claim 1, wherein the at least one lower port (52) is configured to emit a volume of gas between 40 and 600 cfm.

6. A method of using the multiple chamber material-stirring lance (40) in claim 1, the method comprising the steps of: Positioning the multiple chamber material-stirring lance vertically into a quantity of hot metal inside a ladle; Introducing a quantity of material into the material chamber; Introducing a volume of stirring gas into the gas chamber; Discharging the quantity of material from the material chamber through at least one material port and into the quantity of hot metal; and Discharging the volume of stirring gas through the lower port where the stirring gas is emitted with a cfm between 40 and 600 cfm, the discharged gas forming a plurality of bubbles simulating a boiling effect in the hot metal.

7. The method of claim 6, wherein the steps of discharging the quantity of material and discharging the volume of stirring gas is performed simultaneously.

8. The multiple chamber material-stirring lance in claim 1, wherein the opposed outlet of the at least one lower port is positioned in the gas chamber wall directly above and in vertical spaced apart relationship with the at least one material discharge port.

9. The multiple chamber material-stirring lance in claim 4, further comprising a second body port and a third body port, wherein the at least one body port, the second body port and the third body port are arranged as a spiral array of ports about the gas chamber wall having at least two of the body ports in vertical spaced-apart relationship about the gas chamber wall separated by no more than 45 degrees about the gas chamber wall circumference such that the at least two ports are vertically unaligned.

10. A method of using the multiple chamber material-stirring lance having at least one material chamber and at least one gas chamber of claim 9 during a steel purification process, the method comprising the steps of: Positioning the multiple chamber material-stirring lance vertically into a quantity of hot metal inside a ladle; Introducing a quantity of material into the material chamber; Introducing a volume of stirring gas into the gas chamber; Discharging the quantity of material from the material chamber through at least one material port and into the quantity of hot metal; and Discharging the volume of stirring gas through the lower ports where the stirring gas is emitted with a cfm between 40 and 600 cfm, and where the discharged gas forms forming a plurality of bubbles simulating a boiling effect in the hot metal.

11. The multiple chamber material-stirring lance (40) of claim 1, further comprising a second material chamber having an exterior wall adjacent the exterior wall of the material chamber and the outer wall of the gas chamber, and wherein the exterior wall of the second material chamber is encased by the refractory coating (46).

12. The multiple chamber material-stirring lance (40) in claim 1, wherein the material chamber (43) terminates in a pipe having a pair of opposed material discharge ports (60).

13. The multiple chamber material-stirring lance (40) in claim 11, wherein the material discharge ports are opposed pairs of material discharge ports.

14. The multiple chamber material-stirring lance (40) in claim 1, further comprising a terminal lower port (52) leading out of the terminal end of the gas chamber (48) to an exterior of the multiple chamber material-stirring lance (40).

15. The method of claim 6, wherein the step of discharging the volume of stirring gas is performed after the step of introducing the volume of stirring gas into the gas chamber and before the step of discharging the quantity of material from the material chamber.

16. The method of claim 10, wherein the step of discharging the volume of stirring gas is performed after the step of introducing a volume of stirring gas and before the step of discharging the quantity of material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The features and advantages of the invention will become apparent from a consideration of the subsequent detailed description presented in connection with accompanying drawings, in which:

(2) FIG. 1 is a side elevation, cross sectional view of a first embodiment of a multiple chamber material-stirring lance according to the invention, where a single material chamber is adjacent and parallel to a single gas chamber.

(3) FIG. 1a is a top cross sectional view of the multiple chamber material-stirring lance in FIG. 1 taken along section A-A.

(4) FIG. 1b is a top cross sectional view of the multiple chamber material-stirring lance in FIG. 1 taken along section D-D, showing a configuration of gas ports.

(5) FIG. 1c is a top cross sectional view of the multiple chamber material-stirring lance in FIG. 1 taken at section E-E in having a T-material port configuration.

(6) FIG. 2 is a side elevation, cross sectional view of a second embodiment of the multiple chamber material-stirring lance featuring an array of body ports along a body length of the gas chamber.

(7) FIGS. 2a-h are top cross sectional views of the multiple chamber material-stirring lance of FIG. 2 taken along sections A-A, B-B (upper section, middle section, lower section), C-C (upper section and lower section), D-D, and E-E, respectively.

(8) FIGS. 3-4 are side cross sectional views of a method of using the multiple chamber material-stirring lance of FIG. 1 shown with the lance in a ladle of hot metal.

(9) FIGS. 5-6 are side cross sectional views of a method of using the multiple chamber material-stirring lance of FIG. 2 shown with the lance in a ladle of hot metal.

(10) FIG. 7 is a side cross sectional view of the multiple chamber material-stirring lance of FIG. 1, shown with a lower port 52 configuration wherein a lower port 52 is positioned at a lowermost terminal end of the gas chamber with the port opening parallel to the gas chamber.

DRAWINGS LIST OF REFERENCE NUMERALS

(11) The following is a list of reference labels used in the drawings to label components of different embodiments of the invention, and the names of the indicated components. 2 ladle 4 slag pot 5 desulfurization reagent or material 6 hot metal 6a surface of hot metal 8 ladle spout 10 gas bubbles 24 slag 40 multiple chamber material-stirring lance 42 material connection pipe 43 material chamber 44 gas connection pipe 46 refractory coating 48 stirring gas chamber or gas chamber 50 body stirring port or body port 52 lower stirring port or lower port 60 material discharge port

GLOSSARY OF IMPORTANT TERMS

(12) Hot metal or molten metal: metal heated to a temperature such that the metal is in a liquid state, and includes metals commonly purified by heating in a ladle such as steel and iron

(13) Material: desulfurization reagent or reagents

(14) Port: when referring to a port of a gas chamber, a structure capable of passing gas, including but not limited to porous plugs, directional plugs, pipes, and nozzles, and when referring to a port of a material chamber, a structure that allows material to pass through.

DETAILED DESCRIPTION

(15) A multiple chamber material-stirring lance 40 and method of use is shown in FIGS. 1-7

(16) Turning now to FIG. 1, in a first embodiment the multiple chamber material-stirring lance 40 is shown in a side elevation, cross sectional view and in FIGS. 1a-c, showing the lance of FIG. 1 from several top cross sectional views, the multiple chamber material-stirring lance comprising a pair of parallel chambers, a first chamber being a stirring gas or gas chamber 48 having a gas connection pipe 44 at an uppermost end, a body having a length formed leading from the gas chamber 48 to an exterior of the gas chamber, and terminating in at least one or more lower stirring ports or lower ports 52 positioned at a lowermost end of the gas chamber 48. FIG. 7 shows a typical lower port 52 configuration when the gas chamber terminates in three lower ports 52. The lower ports 52 are typically directional plugs, porous plugs, nozzles, pipes or some other type of structure capable of passing gas which emit relatively smaller gas bubbles as compared to a simple open pipe end that freely allows gas to be discharged from the gas chamber 48.

(17) A material chamber 43, located adjacent to the gas chamber, having a material connection pipe 42 at an uppermost end terminates in one or more material discharge ports 60 at a lowermost end of the material chamber 43. While not shown in the Figures, when a single material port 60 is used, the port exit opening is typically located at a lowermost terminal end of the material chamber (straight lance configuration). A lance refractory coating 46 covers and encases the exterior of the gas chamber to protect it from damage caused by submerging the multiple chamber material-stirring lance 40 into a quantity of hot metal 6 in a ladle 2, the lower ports 52 allowing gas present in the gas chamber 48 to exit the multiple chamber material-stirring lance 40.

(18) FIGS. 2 and 2a-h are side and top cross sectional views of a second embodiment of the multiple chamber material-stirring lance 40, where the gas chamber 48 is formed with at least one or more body ports 50 formed into a length of the gas chamber 48 above the lower ports 52. The body ports 50, like the lower ports 52, are directional and/or porous structures that emit relatively smaller gas bubbles as compared to an open pipe end that does not limit or otherwise alter the flow rate of the gas from the gas chamber. The inventor notes that gas ports, whether they are lower ports 52 or body ports 50, are structures that control the flow of gas out of the gas chamber and into the hot metal. In contrast, material ports 60 allow material, such as powdered reagent with a gas carrier such as nitrogen to freely exit the material ports without regulation. The array of body ports shown in FIG. 2 is one example of a typical array of body ports and is not meant to limit the invention to just this particular array. A single body port along the length of the gas chamber body, or two body ports along the length of the gas chamber body above the lower ports 52, for instance are also suitable variations of the array shown in FIG. 2 and would also effectively carry and mix the material into the hot metal inside the ladle.

(19) Turning now to FIGS. 3-6 a method of using the multiple chamber material stirring lance 40 is described. During desulfurization, the multiple chamber material-stirring lance 40 is positioned vertically into the ladle 2 containing the hot metal 6. A quantity of desulfurizing reagent or material 5 is deposited into the material chamber 43 via the material connection pipe 42, and exits the material chamber 43 via the material discharge ports 60 and into the hot metal 6. A volume of gas is introduced through the stirring gas connection pipe 44 and discharged into the hot metal 6 via the lower ports 52, as in FIGS. 3-4 or through the lower ports 52 and an array of ports 50 arranged along the length of the gas chamber, as in FIGS. 5-6, at a same time as the material 5 is discharged into the hot metal, or at a time, as determined by a mill operator controlling the desulfurization process. As shown in FIGS. 3-6, the gas is introduced below a surface 6a of the hot metal 6 and a plurality of bubbles 11 from the gas disperses the material 5 throughout the hot metal 6, resulting in increased reaction between reagent and sulfur, forming slag 24 that moves to the surface of the hot metal and floats along the surface 6a, to be later removed by skimming. The use of pipes, nozzles, directional or porous port structures for the lower stirring ports 52 and/or the plurality of body ports 50 results in relatively smaller bubbles, and when gas introduced into the gas chamber 48 is under relatively higher pressure, typically between 40-600 cfm, the escaping gas bubbles create a boiling effect in which a plurality of small bubbles mixing with the reagents or vaporized material outwards and into the hot metal, enhancing the mixing of material with the hot metal, resulting in a more efficient desulphurization process. FIGS. 4 and 6 illustrate the boiling effect of the bubbles emitted into the quantity of hot metal, resulting in a more efficient dispersion of the material throughout the hot metal as compared to prior art mixing methods. The boiling effect of the gas bubbles moves the material outwards and away from the lance body, exposing the material to more sulfur and capturing it, so it can carry it to the slag layer for removal.

(20) When the multiple chamber material-stirring lance 40 is in use, the material 5 is dispersed from the material ports 60 and stirring gas bubbles 11 emitted from the lower gas ports 52 and/or the plurality of body ports 50 create turbulence in the hot metal 6. The inventor notes that the lower gas ports 52 of the multiple chamber material-stirring lance can also be configured as an array of ports about the terminal end of the gas chamber 48, where a series of pipes radiate outwards from the chamber 48 with each pipe ending in porous and/or directional port structures that regulate the flow of gas so as to control the boiling effect of the stirring gas bubbles and to allow the creation of different stirring gas patterns, as desired.

(21) The inventor notes that while the Figures show a single material chamber and a single gas chamber, it is possible to introduce multiple material and multiple gas chambers within a same lance body. The inventor notes the stirring gas can be introduced into the hot metal with or without material also being introduced, providing the mill operator flexibility of use of the multiple chamber material-stirring lance 40. The inventor stresses that his use of the term port, in the singular or plural, includes any gas permeable structure such as porous or directional plugs, nozzles, and pipes, and the Figures may show a particular type of port, such as a porous plug as an example of a suitable structure and is not meant to limit the meaning of port to only refer to the specific type of structures as shown in the Figures but is meant to illustrate one type of suitable port according to the invention. The inventor also notes that directional plugs, which have a gas permeable slit or slot are also suitable gas permeable structures for use with the invention. The term porous plugs also includes plate type porous material. Port size, regardless of the type of permeable structure used, varies between 0.125 to 5 inches (0.315 to 12.7 cm) in diameter and the lance can be manufactured so as to vary port sizes in a single lance, according to desires or needs of the mill operator. Varying port sizes will impact the volume of gas flowing through the ports relative each other.

(22) The inventor notes the multiple chamber material-stirring lance 40 provides many benefits to the mill operator. The weight of the lance 40 for instance, is essentially the same as that of a standard prior art lance. Thus the multiple chamber material-stirring lance 40 can be installed onto an existing lance drive system with no structural modifications required. The only modifications to the lance drive system consist of an additional gas manifold and an additional hose to a top of the lance 40 to deliver gas to the lance 40, relatively simple and inexpensive modifications.

(23) The mill operator using the multiple chamber material-stirring lance is afforded significant cost reductions and efficiency/quality increases. Steelmaking efficiency is improved without incurring the additional capital equipment cost as required by the prior art systems, and as the multiple chamber material-stirring lance 40 is a combined material and gas stirring lance, only a single lance must be replaced. The mill operator may use gas only, or have gas and material introduced into the hot metal simultaneously, or at different times or different frequencies, as desired, allowing the mill operator the most flexibility and functionality with a single lance, and represents significant cost savings for the mill operator, as a single lance (and its requisite equipment) can achieve a same or better results as the dual material lance systems previously patented, and without substantive capital investment by the mill operator.

(24) It is to be understood the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the scope of the present invention. For instance, the invention is shown with chambers and the exterior lance body as being generally cylindrical in shape, with a circular cross section, however other shapes, such as triangular and hexagonal prisms, with triangular and hexagonal cross sections, cubes and cuboid, with square and rectangular cross sections, or other three dimensional shapes, even spherical or irregular can also be used. The inventor stresses that the combination of gas and material chambers in a single lance, the port configurations which maximize mixing of material within the hot metal, and the ability to control the volume and/or rate of flow of stirring gas via port size, type, and location are key features of the multiple chamber material-stirring lance. Whether the chambers have square or other shaped cross sections, or flat walls versus curved, are variations that are inconsequential to the functioning of the invention, and the circular cross sections shown in the Figures are not meant to exclude these other possible shapes for the coaxial chambers but are just an example of one possible useful shape.

(25) The inventor also notes that the array of body ports shown in FIG. 2 is one example of a typical array of body ports and is not meant to limit the invention to just this particular array. A single body port along the length of the gas chamber body, or two body ports along the length of the gas chamber body above the lower ports 52 are also suitable variations of the array shown in FIG. 2 and would also effectively carry and mix the material into the hot metal inside the ladle.