Title of Invention

PROCESS FOR PRODUCING SPONGE IRON

Abstract

An apparatus for producing sponge iron from iron oxides in lumps in a reduction stack by using a hot dust laden reduction gas such as herein described, which is generated in a gas producer (14) by a partial oxidation of solid carbon carriers and led into said reduction stack via lateral reduction gas inlets at the lower end of the reduction zone, wherein said iron oxides in lumps are fed in the upper area of said reduction stack and radially withdrawn outwards as sponge iron at the lower end thereof by means of withdraw units (3), characterized in that an additional aperture for the sponge iron is provided in the central area of said reduction stack downstream the surface formed between the inner ends of said withdraw units (3) inside the bottom of said reduction stack.

Full Text

-2- The invention relates to an apparatus according to the preamble of claim 1. With the reduction of iron oxides in lumps in a reduction stack the generated sponge iron is withdrawn therefrom in the lower part of the reduction stack. One possibility of withdrawing is to laterally carry off the sponge iron from the reduction furnace by means of radially acting withdraw units, in particular feed screws. By a radial arrangement of said feed screws lateral spaces (dead surfaces) consist between them, which expand toward the inner wall of the reduction . stack. Calm zones of the burden downward moved through the stack so called "dead men" constitute on these space surfaces. Furthermore, it is problematic to enlarge the withdraw units to any extent in view of its diameter and its length for reasons of strength, such that a dead surface normally exists as well in the centre of the reduction stack between the inner ends of the withdraw units (feed screw heads) upon which a "dead man" (central "dead man") also constitutes. The height of these "dead men" depends on the size of the respective space surface and repose angle of the burden bulk. In particular, with higher dustings due to the dust content of the reduction gas, this repose angle is very steep and the internal friction is very high. Moreover, the "dead men" formed above the space surfaces of the feed screws and the central "dead man" can support each other. The "dead men" comprise a potentially harmful influence on the uniformity of the gas evolution of the burden as well as on the burden motion inside the stack and on the continuity of the reduction of the iron oxides therewith. 3 Hence, it is an object of the present invention to provide an apparatus for producing sponge iron from iron oxides in lumps inside a reduction stack by using a hot dust laden reduction gas, which is generated in a gas producer by a partial oxidation of solid carbon carriers and led into the reduction stack via lateral reduction gas inlets at the lower end of the reduction zone, wherein the iron oxides in lumps are fed in the upper area of the reduction stack and radially withdrawn as sponge iron at the lower end thereof by means of withdraw units, in which at least the dead surface in the centre between the radial withdraw units in the bottom plane of the reduction stack is avoided. This object is solved according to the invention by the features indicated in the characterizing part of claim 1. Advantageous improvements of the apparatus according to the invention result from the subclaims. As a result of providing an additional withdraw aperture for the sponge iron in the central area of the reduction stack below the surface formed between the inner ends of the withdraw units in the bottom of the reduction stack, "dead men" may not constitute in the centre, and substantially laterally between the withdraw units as well, since the central surface itself serves as a withdraw aperture, and also the burden material being above the side surfaces can no longer support against the central "dead man", but with sxnkxng down inside the reduction stack is directed on the contrary in a considerable part toward the additional withdraw aperture. Advantageously a guide means is provided between the respective two withdraw units and upwards protruding beyond these, such that the sponge iron sinking down is directed laterally toward the withdraw units and directed radially to the additional withdraw aperture. Because of this an intensified guidance of burden material toward the withdraw units and additional withdraw aperture is achieved. The guide means preferably comprise an upper edge obliquely extending upwards from the margin of the additional withdraw aperture to the inner wall of the reduction stack and expand downward and radially outwards to the width of the lateral space between the withdraw units. Because of this it is ensured, that the entire burden material sinks down continuously until it is withdrawn. By separating the outlet into an external area and a central area the settling speed in the area of the outer stack diameter and in the area above the central withdraw can be controlled independently from each other. Thus a purposeful control of the stack operation across the entire stack section is possible in conjunction with the individually adjustable withdraw speeds of the withdraw units. Advantageously a vertical stack with a constant diameter conforming to the diameter of the withdraw aperture is positioned below the additional withdraw aperture, wherein said stack is locked at the lower end and wherein at least a further radially acting withdraw unit for sponge iron is disposed above the stack bottom. In the following the invention is further explained according to embodiments shown in the accompanying figures, in which Fig. l shows the lower part of a reduction stack in a vertical section view according to a first embodiment; Fig. 2 shows a horizontal section view through the reduction stack taken along the plane II-II in Fig. 1; and Fig. 3 shows the lower part of a reduction stack in a vertical section view according to a second embodiment. The figures show the part of the reduction stack below the bustle plane, that is the plane, in which the reduction gas is blown into the stack in order to rise upwards inside thereof through the burden and in order to effect converting of iron oxides to sponge iron. The reduction stack comprises a cylindrical or sectionalized conical casing 1, which changes into the bottom 2 at the lower end. Some withdraw apertures, such as ten lateral withdraw apertures for the burden containing the sponge iron are directly located above the bottom 2, wherein the apertures are circumferentially distributed along said casing 1 in a horizontal plane and in a uniform distance. A withdraw unit in form of a feed screw 3 is directed through each of these withdraw apertures. The feed screws 3 radially convey outwards the burden sunken upon the bottom 2, such that it passes into a downpipe 4, respectively, through which it is conducted for example into a melt-in gasifier generating the reduction gas. This burden discharge enables sinking down of burden inside the reduction stack. The radial feed screws 3 only extend beyond a part of the reduction stack radius, such that the feed screw heads comprise a distance from the stack axis and forming a circular area between themselves. The bottom 2 includes a central withdraw aperture corresponding to said circular area, which verges into a cylindrical stack 5 with a diameter being accordingly reduced with respect to that of the reduction stack. Above the bottom 2 a wedge-shaped guide element 6 is located between the respective two feed screws 3. The front and upper edge of the guide element, respectively extends from the margin of the central withdraw aperture rising upwards to the inner wall of the casing l, wherein the angle of slope of this edge is 25 to 40° with respect to the normal. Furthermore, the guide means 6 expand downward and radially outwards extending from this edge, such that its surface leaning on the bottom corresponds to the dead surface beetween two feed screws 3, respectively. The angle of slope of the side surfaces of guide elements 6 is approximately within the range of 5 to 15°. The guide elements 6 direct the burden falling down toward the central withdraw aperture inside the bottom 2 as well as toward the feed screws 3 in a manner, such that practically the entire burden is freely withdrawn, that means occurring of "dead men" is paralysed. The part of burden passing the central withdraw aperture comes into the stack 5 being closed downward. In order to withdraw the material therefrom, two withdraw apertures are provided which are located directly above the bottom of the stack 5 and diametrically opposite, through which each one feed screw 7 is directed as well for withdrawing to a downpipe 8, which also leads into the melt-in gasifier. Since the diameter of the stack 5 is significantly smaller than that of the reduction stack, the feed screws 7 each protrude beyond the centre of the stack 5, such that all burden entering into the stack 5 is moved to the downpipes 8 without jam. Instead of the feed screws 8 other withdraw units can be provided in the bottom of the stack 5, for example a cellular wheel sluice or a bunker reclaiming wheel. With the reduction stack according to Fig. 3 the central withdraw aperture inside the bottom 2 is followed by a stack 9, which internal diameter decreases continuously and is about 1 m or less at the lower end. The lower end of the stack 9 is open such that the burden can emerge therefrom. It falls down on a walking beam 10, which is inside a chamber 11 having an outlet tube 12. Depending on the quantity of the burden emerged from the stack 9 the walking beam 10 accomplishes swivelling movements and effects a discontinuous withdraw therefrom to the outlet tube 12. 7 The outlet tube 12 is centrally directed through a coal inliner 13 into the head of a melt-in gasifier 14. The coal inliner 13 includes a vertical supply pipe from a coal bunker and a two-stage feed screw. By concentrical insertion of burden material and sponge iron respectively and coal into the head of the melt-in gasifier 14 mixing thereof is supported, such that melting of sponge iron and the generation of the reduction gas in the melt-in gasifier 14 are improved. WE CLAIM: 1. Process for producing sponge iron from iron oxide lumps in a reduction shaft, using a hot dust laden reduction gas which is produced in a gas generator (14) by partial oxidation of solid carbon carriers and introduced via lateral reduction gas inlets at the lower end of the reduction zone into the reduction shaft, and where the iron oxide lumps are fed into the upper area of the reduction shaft and radially delivered at its lower end by delivery organs (3) as sponge iron, and in which an additional delivery opening for sponge iron is provided in the central area of the reduction shaft below the surface formed between the inner ends of the delivery organs (3) in the base of the reduction shaft, characterised in that the delivery organs (3) convey sponge iron only radially outward. 2. Process according to Claim 1, characterised in that the downward sinking sponge iron is diverted laterally to the delivery organs (3) and radially to the additional delivery opening by a guiding device (6) arranged between two respective delivery organs (3) and upwardly protruding over the latter. : 8 : 3. Process according to Claim 1 or 2, characterised in that screw conveyers (3) are used as delivery organs. 4. Process according to one of Claims 1 to 3, characterised in that a guiding device (6) is used the upper edge of which extends from the edge of the additional delivery opening at a slant upward to the inside wall of the reduction shaft. 5. Process according to Claim 4, characterised in that a guiding device (6) with an inclination angle of the upper edge of between approximately 25 and 40° relative to the vertical is used. 6. Process according to one of Claims 1 to 5, characterised in that a guiding device (6) is used which extends downward and radially outward up to the width of the lateral intermediate space between the delivery organs (3). 7. Process according to Claim 6, characterized in that a guiding device (6) is used which as an inclination angle of its lateral surfaces of between approximately 5 and 30° relative to the vertical. : 9 : 8. Process according to one of Claims 1 to 7, characterised in that a reduction shaft is used which has a shaft (5) located below the additional delivery opening with downwardly narrowing, unchanging or increasing diameter, the lower end of which is sealed and wherein above the base is arranged at least one further radially operational delivery organ (7) for sponge iron. 9. Process according to Claim 8, characterised in that a screw conveyer (7) is used as an additional delivery organ. 10. Process according to Claim 8, characterised in that a rotary-vane feeder is used as additional delivery organ. 11. Process according to Claim 8, characterised in that a bunker cleaning device is used as additional delivery organ. 12. Process according to one of Claims 1 to 7, characterised in that a reduction shaft is used which has a vertical shaft (9) located below the additional delivery opening and with downwardly decreasing diameter, which has at the lower end a delivery opening for sponge iron and terminates in a chamber (11) with delivery pipe (12) in which a lifting beam (10) is provided below the delivery opening at the lower end of the shaft (9). : 10 : 13. Process according to Claim 12, characterized in that a delivery pipe (12) is used which is ducted through the delivery pipe (13) for delivery of solid carbon carriers into the gas generator. Dated this 21st day of August 1998. S BANERJEE OF L S DAVAR & CO Agent for the applicant 11 An apparatus for producing sponge iron from iron oxides in lumps in a reduction stack by using a hot dust laden reduction gas such as herein described, which is generated in a gas producer (14) by a partial oxidation of solid carbon carriers and led into said reduction stack via lateral reduction gas inlets at the lower end of the reduction zone, wherein said iron oxides in lumps are fed in the upper area of said reduction stack and radially withdrawn outwards as sponge iron at the lower end thereof by means of withdraw units (3), characterized in that an additional aperture for the sponge iron is provided in the central area of said reduction stack downstream the surface formed between the inner ends of said withdraw units (3) inside the bottom of said reduction stack.

Documents:

01503-cal-1998-abstract.pdf

01503-cal-1998-claims.pdf

01503-cal-1998-correspondence.pdf

01503-cal-1998-description(complete).pdf

01503-cal-1998-drawings.pdf

01503-cal-1998-form-1.pdf

01503-cal-1998-form-2.pdf

01503-cal-1998-form-3.pdf

01503-cal-1998-form-5.pdf

01503-cal-1998-pa.pdf

01503-cal-1998-priority document other.pdf

01503-cal-1998-priority document.pdf

1503-CAL-1998-(16-10-2012)-FORM-27.pdf

1503-CAL-1998-FORM-27.pdf

1503-cal-1998-granted-abstract.pdf

1503-cal-1998-granted-claims.pdf

1503-cal-1998-granted-correspondence.pdf

1503-cal-1998-granted-description (complete).pdf

1503-cal-1998-granted-drawings.pdf

1503-cal-1998-granted-examination report.pdf

1503-cal-1998-granted-form 1.pdf

1503-cal-1998-granted-form 2.pdf

1503-cal-1998-granted-form 3.pdf

1503-cal-1998-granted-form 5.pdf

1503-cal-1998-granted-letter patent.pdf

1503-cal-1998-granted-others.pdf

1503-cal-1998-granted-pa.pdf

1503-cal-1998-granted-priority document.pdf

1503-cal-1998-granted-reply to examination report.pdf

1503-cal-1998-granted-specification.pdf

1503-cal-1998-granted-translated copy of priority document.pdf

1503-CAL-1998-OTHER PATENT DOCUMENT.pdf