MXPA00005610A - Direct smelting vessel - Google Patents

Abstract

A direct smelting vessel which is adapted to contain a molten bath of metal and slag is disclosed. The vessel includes an off-gas duct that has:(a) a first section which has a relatively slight upward inclination to the horizontal from an inlet end of the first section;and (b) a second section which extends upwardly from an upper end of the first section at a relatively steep inclination to the horizontal.

Description

DIRECT FOUNDRY CONTAINER DESCRIPTION OF THE INVENTION The present invention relates to a direct casting vessel for producing molten metal (a term which includes metal alloys) from metalliferous feedstock such as ore and partially reduced ores. The present invention relates particularly to a container that can be used for direct casting processes based on molten bath. It is understood herein that the term "smelting" means thermal processing wherein chemical reactions that reduce metal oxides to produce liquid metal are carried out. Herein is meant the term "direct casting process" which means a process that produces a molten metal directly from a metalliferous feedstock, such as iron ore and partially reduced iron ore. The present invention relates particularly to gas discharge ducts for direct casting vessels.

REF.120958 An objective of the present invention is to provide a gas discharge pipeline which minimizes the losses of molten material and solids entrained with the gas discharge. In accordance with the present invention, there is provided a direct casting vessel which is adapted to contain a liquid bath of slag and metal and includes: a melting chamber or crucible; side walls extending upwardly from the fusion chamber; a roof; and a gas discharge pipe that extends from an upper section of the container for discharging the container from a gas discharge that occurs during the direct melting process carried out in the container, gas discharge pipe which includes: ( a) a first section which has a slight upward inclination, towards the horizontal from an entrance end of the first section; and (b) a second section which extends upwards from an upper end of the first section at a relatively steep inclination with respect to the horizontal. In use, the gas discharge is forced to undergo a substantial change of direction in order to enter the first section. It is considered that, as a consequence, the molten material and the solids that are entrained in the gaseous discharge contact and deposit on: (i) the walls of the container that are in or within the region of the inlet end; and (ii) the walls (particularly the top walls) of the first section in or within the region of the entry end; and therefore they separate from the gas discharge. The molten material and solids deposited in these walls move down into the interior of the container. Further, in operation, the gas discharge flow along the first section is forced to undergo a substantial change of direction at the end of the first section so as to flow into the second section. Consequently, the molten material and the solids that are entrained in the gas discharge tend to contact and deposit in the wall that extends upwards, that is, at the end of the first section and separate from the gas discharge. It is considered that in this region of the duct, the molten material remains molten or solidifies on the wall. The molten material that remains molten flows down into the first section and then along the first section into the container. The molten material that solidifies accumulates in the wall and with the deposited solids finally splinters and falls down into the interior of the first section. In view of the relatively higher temperature conditions in the first section, the solidified material melts and flows back into the container or otherwise is transported by the molten material back to the container. inside of the container. The first slightly inclined section avoids the potentially serious problems of solid accretions falling back into the container and damaging equipment such as nozzles / spears while carrying out a direct casting process on the container or after a shutdown. Such return flow is also a potentially serious safety concern for people who carry out maintenance work on the container for an off period. Preferably, the first section is formed by considering the operating conditions of the container so that at least a substantial part of the molten material entering the first section with the gas discharge melts at the end of the first slightly inclined section. This ensures that there is a minimum accumulation of solid accretions in the first section. More preferably in this respect, the first section is formed so that the temperature decreases along the length of the first section is less than 100 ° C and the total temperature is maintained above the melting points of the first section. molten material.

Preferably, the amount of entrained material (molten and solids) in the gaseous discharge discharged from the second section is less than 15 g, more preferably less than 10 g per Nm 3 of gas discharge. Preferably, the relatively slight upward inclination of the first section is less than 30 °, more preferably less than 20 °, with respect to the horizontal. It is particularly preferred that the angle of inclination is less than 10 °. Preferably, the relatively steep inclination of the second section is 80-90 ° with respect to the horizontal. Preferably, the container includes a closed end inflection containing the first and second sections. Preferably, the closed end inflection includes an access hole in the closed end. Preferably, the container includes a gas discharge chamber that extends upwardly from the roof and the first section of the gas discharge pipe extends from the gas discharge chamber. Preferably, the first section of the gas discharge pipe extends from a side wall of the gas discharge chamber. Preferably, the ratio of the length of the first section to the minimum width dimension of the first section is at least 2: 1, wherein the length of the first section is measured between the intersection of the center lines of the first and second sections and the intersections of the central line of the first section and the vertical line through the entrance end of the first section. In a situation where there is a gaseous discharge chamber and the first section extends from a side wall of the chamber, the intersection of the center line of the first section and a vertical center line of the gaseous discharge chamber is a point of measurement at the entrance end of the first section. Typically, the first and second sections are cylindrical and the minimum width dimension of the first section referred to in the preceding paragraph is the diameter of the first section. Preferably, the second section is formed so that the decrease of temperature along the length of the second section is sufficient to solidify at least a substantial part of any molten material that is in the gas discharge flowing through the second section before the gas discharge reaches the extreme of the second section. This ensures that there is a minimal drag, if any, of molten material to the downstream gas discharge processing apparatus, such as hot cyclones and hot scrubbers, which can adversely alter the molten material in the gas discharge. Preferably, the gas discharge chamber is located centrally. Preferably, the container includes at least one lance for injecting oxygen containing gas into the container which extends downward through the gaseous discharge chamber into the container. Preferably, the ratio of the minimum width dimensions of the side walls of the container and the gas discharge chamber is at least 1.5: 1. In situations where the gas injection lance or lances containing oxygen extend downwardly through the gas discharge chamber, preferably the ratio is from 1.5H to 2: 1. In situations where the gas injection lance or lances are not located extending through the gas discharge chamber, the ratio of minimum width dimensions can be up to 4: 1. Preferably, the roof is inclined upward from the side walls at an angle in the range of 30 to 50 ° to the horizontal axis (i.e., an inclined angle of 120 to 130 ° measured between the side walls and the roof). Preferably, the angle of inclination is 40 ° with respect to the horizontal axis.

Preferably, the side walls are cylindrical and the roof is frustroconical and extends from an upper end of the side walls and ends in the gas discharge chamber. Preferably, the minimum width dimension of the side walls of the container is 8 meters. In accordance with the present invention, a direct casting process operated in the container described above is also provided. The present invention is further described by way of examples with reference to the accompanying drawings, of which: Figure 1 is a vertical section through a metallurgical vessel schematically illustrating a preferred embodiment of the present invention; and Figure 2 is a vertical section through an upper section of another metallurgical vessel illustrating another preferred embodiment of the present invention. The following description is in the context of the direct casting of iron ore to produce cast iron in accordance with a form of the Hlsmelt process (registered trademark). It is understood that the present invention is not limited to the direct casting of iron ore and is applicable to any other suitable metal ore and concentrates and other metalliferous feedstocks-including partially reduced metal ores. It is also understood that the present invention is not limited to the Hlsmelt process. The container shown in figure 1 has a melting chamber including a base 3 and sides 55 formed of refractory bricks; side walls 5 which form a generally cylindrical barrel extending upwardly from the sides 55 of the melting chamber which includes an upper barrel section 51 and a lower barrel section 53; a roof 7; a gas discharge duct 9 extending from an upper section of the container; a forehearth 77 for continuously discharging molten metal; and a pouring hole 61, for discharging the molten slag. The gas discharge duct 9 includes a first section 31 slightly inclined towards, upwardly extending from an inlet end 63 at an angle a of 7 ° to the horizontal and a second inclined section 33 extending vertically from the other end of the tube. the first section 31. Both sections, 31 and 33, are cylindrical. The first section 31 is formed, by considering the operating conditions in the container and other relevant factors, so that the molten material entering the first section remains fused along the length of the first section. In other words, the first section is formed so that the temperature in the first section, particularly in the region of the wall, is above that in which the molten material solidifies. The second section 33 is formed such that the temperature decrease from the length of the second section is sufficient to solidify at least a substantial part of any molten material that is in the gaseous discharge flowing through the second. section 33 by the time the molten material reaches the end of the second section 33. In use, the container contains a molten iron and slag bath which includes a layer 15 of molten metal and a layer 16 of molten slag over the metallic layer 15. The arrow marked with the number 17 indicates the position of the quiescent surface of the metallic layer 15, and the arrow marked with the number 19 indicates the position of the quiescent surface of the slag layer 16. It is understood that the term "quiescent surface" means the surface when there is no injection of gas and solids into the container. The container also includes 2 nozzles / nozzles 11 for injecting solids that extend downward and inward at an angle of 30 ° -60 ° to the vertical through the side walls 5 and into the interior of slag layer 16 . The position of the nozzles / nozzles 11 is selected so that the lower ends are above the quiescent surface 17 of the metallic layer 15.

In use, iron ore (typically fine), solid carbonaceous material (typically coal), and fluxes (typically quicklime and magnesia) entrained in a carrier gas (typically N2) is injected into the metallic layer 15 via the nozzles / nozzles 11. The moment of the solid material / carrier gas causes the solid material and the carrier gas to penetrate the metallic layer. The carbon is devolatilized and therefore produces gas in the metallic layer. The carbon preferably dissolves in the metal and remains partially as solid carbon. The iron ore melts to metal and the melting reaction generates gaseous carbon monoxide. The gases transported into the metallic layer 15 and generated via devolatilization and melting, produce a significant upward flotation of molten metal, solid carbon and slag (extracted in the metallic layer as a consequence of solid / gas injection). from the layer metal which generates an upward movement of splashes, droplets and streams of molten metal and slag, and these splashes, droplets and streams entrain slag as they move through the slag layer 16. The vertical flotation of the molten metal, the solid carbon and the slag causes substantial agitation in the metallic layer 15 and the slag layer 16, with the result that the slag layer 16 expands in volume and has a surface indicated by the arrow 30. The extent of agitation is such that a reasonably uniform temperature exists in the metal and slag regions-typically, 1450-1550 ° C, with a temperature variation in the order of 30 ° C. In addition, upward movement of splashes, droplets and currents of molten metal and slag -caused by the rising flotation of molten metal, solid carbon and slag- extends into the space 71 (the "upper space") above the molten material in the container and forms a transition zone 23. Generally speaking, the slag layer 16 is a liquid continuous volume, with gas bubbles therein, and the transition zone 23 is a continuous volume of gas with splashes, droplets and streams of molten metal and slag. The container further includes a lance 13 for injecting an oxygen-containing gas (typically oxygen-enriched, pre-heated air) which is centrally located and extends vertically downwardly into the container. The position of the lance 13 and the gas flow velocity through the lance 13 are selected so that the oxygen-containing gas penetrates the central region of the transition zone 23 and maintains a space essentially free of metal. slag around the end of the lance 13. The injection of the oxygen-containing gas via the lance 13 produces a subsequent reaction to the combustion of the gases CO and H2 in the transition zone 23 and in the free space around the end of the Launches 13 and generates high temperatures of the order of 2000 ° C or higher in the gas space. The heat is transferred to the splash, droplets and melt streams ascending and descending in the gas injection region and the heat is then partially transferred to the metal layer when the metal / slag returns to the metal layer. The process described above generates substantial volumes of gas discharge which are at temperatures in the range of 1550 to 1650 ° C and include molten material and entrained solids. The solids in the entrained material are generally in powder form. The gas discharge flows from the upper space 71 into the first slightly inclined section 31 of the gas discharge duct 9 via the inlet end 63, along the length of the first section 31, around the narrow radius corner in the end of this section, and then upwards, through the second section 33. The gaseous discharge undergoes pronounced changes in the direction at the entrance end 63 of the first section 31 and at the narrow radius corner joining the first and second sections. As discussed beforeThese pronounced changes in direction cause the molten material and the solids that are entrained in the gaseous discharge to make contact and are deposited in the upper wall of the duct in the region with a circle A and on the end wall of the duct in the region. with circle B. In the case of region A, it is considered that the molten material deposited remains molten and flows down into the container, and that the deposited solids are carried by the molten material back into the container. In the case of region B, it is believed that part of the molten material remains molten and the remainder of the molten material solidifies. The molten material that remains molten flows down the end wall into the first section 31 and then along the first section 31 into the interior of the container. The molten material that progressively solidifies builds up on the wall and finally splinters and falls down into the first section 31. By forming the first section 31 so that the temperature along the length of the first section is above from that to which the molten material solidifies, it is ensured that at least a substantial part of the solidified material melts and flows downward from the slight inclination into the interior of the container. Solids that remain solid are transported by the molten material back into the container. The gas discharge pipe 9 described above makes it possible to remove substantial quantities of molten entrained material and solids from the gas discharge with the result that the total amount of entrained material (ie molten material and solids) discharged from section 33 is maintained below 15 g per Nm3 of gas discharge. In addition, the first section 31 slightly inclined avoids the potentially serious problem falling back to solid pressures inside the container and damaging equipment such as nozzles / lances while the direct casting process is performed in the container or after a period of time. off. In addition, the first section 31 slightly inclined makes it possible to leave the upper part of the container free and therefore allows the access of cranes to remove and resorption of the gas injection lance 13 containing oxygen and to allow otherwise the access of cranes to the interior of the container via the upper part of the container, which may be required during the operations of coating application again. The basic components, that is, the melting chamber, the side walls, the roof and the gas discharge pipe, the solids injection lances and the gas injection lance containing oxygen from the container shown in figure 2 they are the same as for the container shown in figure 1. Furthermore, the melting process based on basic molten bath operated in the container shown in figure 2 is the same as that described in relation to figure 1. In Consequently, Figure 2 and the following description of the figure focus on the differences between the two embodiments of the present invention. With reference to Figure 2, the container includes a cylindrical gas discharge chamber 79 which extends upwardly from the roof 7 and the gas discharge pipe 9 extends from the side wall 93 of the gas discharge chamber 79. An upper wall 91 of the gas discharge chamber 79 is formed as a removable access hole to allow access to the container. The gas discharge chamber 79 is positioned centrally and, consequently, the roof 7 is frustoconical in shape and defines an included angle of 130 ° with the upper barrel section 51 of the side walls 5 of the container. The ratio of the diameters of the upper barrel section 51 and the gas discharge chamber 79 is 1.8: 1. Although not shown, the gas injection lance 13 containing oxygen is placed to extend downwardly., through the upper wall 91 of the gas discharge chamber 79. The first section 31 of the gas discharge pipe 9 extends at an angle α of 7 ° to the horizontal, and the second section 33 extends vertically from the first section 31.

The dimensions of the first section 31 of the gas discharge pipe 9 are selected such that the ratio of the length L of the first section 31 (measured between the intersection of the center lines of the first and second sections 31, 33 and the intersection of the center line of the first section and the vertical center line of the gaseous discharge chamber 79) and the diameter D of the first section 31, is 3.7: 1. In use, the gaseous discharge undergoes significant changes of direction in order to enter the first section 31 from the gas discharge chamber 79 in order to enter the second section 33 from the first section. As described above in relation to the embodiment of Figure 1, these significant changes in direction cause deposition of molten entrained material and solids on exposed surfaces of regions with circles A and B, and facilitate the removal of the entrained material (melts and solids). ) of the gas discharge. The second section 33 of the gas discharge duct 9 is placed in an upper wall of the first section 31 of the gas discharge duct 9 so that the end wall 87 of the first section 31 forms a closed end inflection and, when uses, there is an accumulation of material dragged (molten and solid) -as indicated by the section shaded in the figure- which protects the end wall. In addition, the end wall 87 of the first section 31 of the gas discharge pipe 9 is formed as a removable access hole to allow access to the duct. Many modifications can be made to the preferred embodiments of the present invention described above without departing from the spirit and scope of the invention. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers.

Claims (40)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A direct casting vessel, which is adapted to contain a molten bath of metal and slag and which includes: a melting chamber or crucible; side walls extending upwardly from the fusion chamber; a roof; and a gas discharge pipe that extends from an upper section of the container for discharging the container from a gas discharge that occurs during the direct melting process carried out in the container, gas discharge pipe which is characterized in that it includes: (a) a first section which has a slightly upward inclination with respect to the horizontal from an entrance end of the first section; and (b) a second section which extends upwards from an upper end of the first section at a relatively steep inclination with respect to the horizontal.

2. The container according to claim 1, characterized in that the relatively slight upward inclination of the first section is less than 30 ° with respect to the horizontal.

3. The container according to claim 2, characterized in that the relatively slight upward inclination of the first section is less than 20 ° with respect to the horizontal.

4. The container according to claim 3, characterized in that the angle of inclination of the first section is less than 10 ° with respect to the horizontal.

5. The container according to any of the preceding claims, characterized in that the relatively steep inclination of the second section is 80-90 ° with respect to the horizontal.

6. The container according to any of the preceding claims, characterized in that the ratio of the length of the first section to a minimum width dimension of the first section is at least 2: 1, wherein the length of the first section it is measured between the intersection of the center lines of the first and second sections and the intersection of the center line of the first section and the vertical line through the entrance end of the first section.

7. The container according to any of the preceding claims, characterized in that it includes a closed end inflection connecting the first and second sections.

8. The container according to claim 6, characterized in that the closed end inflection includes an access hole in the closed end.

9. The container according to any of the preceding claims, characterized in that it includes a gas discharge chamber that extends upwards from the roof and the first section of the gas discharge pipe extends from the gas discharge chamber.

10. The container according to claim 9, characterized in that the ratio of the minimum width dimensions of the side walls of the container and the gaseous discharge chamber is at least 1.5: 1.

11. The container according to claim 9 or claim 10, characterized in that the first section of the gas discharge pipe extends from a side wall of the gas discharge chamber.

12. The container according to claim 11, characterized in that the ratio of the length of the first section to the minimum width dimension of the first section is at least 2: 1, wherein the length of the first section is measured between the intersection of the center lines of the first and second sections, and the intersections of the center line of the first section and a vertical center line of the gas discharge chamber.

13. The container according to any of claims 9 to 12, characterized in that the upper end of the gaseous discharge chamber d finishes a closed end inflection.

14. The container according to any of claims 9 to 13, characterized in that the gas discharge chamber is located centrally.

15. The container according to any of claims 9 to 14, characterized in that it includes at least one lance for injecting oxygen-containing gas into the container, which extends downwards through the gaseous discharge chamber into the interior of the container.

16. The container according to any of the preceding claims, characterized in that the roof is inclined upwards from the side walls at an angle in the range of 30 to 50 ° with respect to a horizontal axis, that is, an included angle of 120 to 130 °, measured between the side walls and the ceiling.

17. The container according to claim 16, characterized in that the angle of inclination is 40 ° with respect to the horizontal axis.

18. The container according to claim 16 or claim 17, characterized in that the side walls are cylindrical, and the roof is frustroconical and extends from an upper end of the side walls and ends in the gas discharge chamber.

19. The container according to any of the preceding claims, characterized in that the minimum width dimension of the side walls of the containers is 8 meters.

20. A direct casting vessel, which contains a molten metal and slag bath, and includes: a melting chamber or crucible; side walls extending upwardly from the fusion chamber; a roof; and a gas discharge pipe that extends from an upper section of the container for discharging the container from a gas discharge that occurs during the direct melting process carried out in the container, gas discharge pipe which is characterized in that it includes: (a) a first section which has a slightly upward inclination with respect to the horizontal from an entrance end of the first section; and (b) a second section which extends upwards from an upper end of the first section at a relatively steep inclination with respect to the horizontal.

21. The container according to claim 20, characterized in that the relatively slight upward inclination of the first section is less than 30 ° with respect to the horizontal.

22. The container according to claim 21, characterized in that the angle of inclination of the first section is less than 10 ° with respect to the horizontal.

23. The container according to any of claims 20 to 22, characterized in that the relatively steep inclination of the second section is 80-90 ° with respect to the horizontal.

24. The container according to any of claims 20 to 23, characterized in that at least a substantial part of the molten material entering the first section with the gas discharge melts at the end of the first section.

25. The container according to any of claims 20 to 24, characterized in that the temperature decrease along the length of the first section is less than 100 ° C and the total temperature within the first section is maintained above the melting points of the molten material, whereby at least a substantial part of the molten material entering the first section with the gaseous discharge melts at the end of the first section.

26. The container according to any of claims 20 to 25, characterized in that the gaseous discharge discharged from the second section of the gas discharge pipe includes less than 15 g / Nm3 of material drawn by Nm3 gas discharge, where the entrained material consists of of solids and molten material.

27. The container according to any of claims 20 to 26, characterized in that the ratio of the length of the first section to a minimum width dimension of the first section is at least 2: 1, wherein the length of the The first section is measured between the intersection of the center lines of the first and second sections and the intersection of the center line of the first section and the vertical line through the entrance end of the first section.

28. The container according to any of claims 20 to 27, characterized in that it includes a closed end inflection connecting the first and second sections.

29. The container according to claim 27, characterized in that the closed end inflection includes an access hole at the closed end.

30. The container according to any of claims 20 to 29, characterized in that it includes a gas discharge chamber that extends upwards from the roof and the first section of the gas discharge pipe extends from the gas discharge chamber.

31. The container according to claim 30, characterized in that the ratio of the minimum dimensions of the side walls of the container and of the gaseous discharge chamber is in the range of 1.5: 1 to 2: 1.

32. The container according to claim 30 or claim 31, characterized in that the first section of the gas discharge pipe extends from a side wall of the gas discharge chamber.

33. The container according to claim 32, characterized in that the ratio of the length of the first section to the minimum width dimension of the first section is at least 2: 1, wherein the length of the first section is measured between the intersection of the first and second sections, and the intersection of the center line of the first section and a vertical center line of the gas discharge chamber.

34. The container according to any of claims 30 to 33, characterized in that the upper end of the gas discharge chamber defines a closed end inflection.

35. The container according to any of claims 30 to 34, characterized in that the gas discharge chamber is located centrally.

36. The container according to any of claims 30 to 35, characterized in that it includes at least one lance for injecting oxygen containing gas into the container, which extends downwards through the gas discharge chamber into the interior of the container.

37. The container according to any of claims 20 to 35, characterized in that the roof is inclined upwards from the side walls at an angle in the range of 30 to 50 ° with respect to a horizontal axis.

38. The container according to claim 37, characterized in that the angle of inclination is 40 ° with respect to the horizontal axis.

39. The container according to claim 37 or claim 38, characterized in that the side walls are cylindrical, and the roof is frustoconical and extends from an upper end of the side walls and ends in the gas discharge chamber.

40. The container according to any of claims 20 to 39, characterized in that the minimum width dimension of the side walls of the containers is 8 meters.