Title of Invention

METHOD OF REMOVAL OF RESIDUAL PIG IRON OF BLAST FURNACE

Abstract

The present invention is a method for pulling outside of the furnace and removing solidified residual pig iron remaining at the furnace hearth at the time of repair of a blast furnace as split residual pig iron blocks and comprises removing the iron shell at the part for pulling out the split residual pig iron blocks, boring a residual pig iron bottom through hole through which a wire saw is passed in the furnace bottom refractories at the bottom of the residual pig iron, passing a wire saw in the residual pig iron bottom through hole, wrapping the wire saw at the outer circumference of the residual pig iron, running the wire saw to cut the residual pig iron and furnace bottom refractories in the longitudinal direction to split the iron into a plurality of residual pig iron blocks, and pulling the residual pig iron blocks outside the furnace so"as to remove the solidified residual pig iron safety in a short time.

Full Text

DESCRIPTION METHOD OF REMOVAL OF RESIDUAL PIG IRON OF BLAST FURNACE TECHNICAL FIELD The present invention relates to a method of removal of residual pig iron for removing residual pig iron solidified due to cooling and remaining at the furnace hearth of a blast furnace in a short time and safe manner when repairing a blast furnace. BACKGROUND ART When repairing a blast furnace, water is poured into the content of the furnace remaining in a high temperature molten state so as to cool and solidify the content. This solidified content remains at the furnace hearth. The high specific gravity residual pig iron in the content remains as a solid mass at the furnace hearth. The weight ranges from 300 tons to 2000 tons. This removal of residual pig iron remaining at a furnace hearth is an essential step in dismantling a blast furnace body and a critical path when repairing a blast furnace. This residual pig iron removal is extremely difficult work. Many examples have been seen in the past where this removal failed to proceed as scheduled and caused delays in the repair period. Residual pig iron has a large specific gravity and high hardness, so as the method for splitting the residual pig iron into small pieces in a short time, in the past the means of smashing it by blasting has been considered the most suitable. For many years up until now, residual pig iron has been removed by blasting. Therefore, the technology developed in the method of removal of residual pig iron in blast furnace repair has been for means for efficiently smashing and removing residual pig iron by blasting and technology relating to and mechanization of the same (see Japanese Patent Publication (A) No. 2000-256717). FIG. 6a shows an example of a conventional method of removal of residual pig iron by blasting, while FIG. 6b shows an example of the procedure for splitting residual pig iron into small pieces by blasting. A blast furnace is comprised of an iron shell 4 surrounding the outer circumference, refractory bricks lining the inner circumference of the shell, and refractory bricks stacked on the furnace hearth to form furnace bottom refractories 2. When repairing a blast furnace, to remove the residual pig iron 1 solidified by cooling, two facing locations of the iron shell of the furnace hearth part are opened to form iron shell openings 5 of heights of 4 m and widths of 4 m and expose the residual pig iron 1. The exposed residual pig iron I is bored by a drill of a residual pig iron boring machine 15 to form a blasting hole. The depth of the blasting hole is about 1.5 m or so. This blasting hole is packed with explosives and blasted to split the iron into small pieces. The split small pieces of residual pig iron 1 are dug out using a bulldozer shovel or other heavy machinery 16 and removed. Due to the above work, the worker repeatedly splits and removes the iron from reference numeral (1) shown in FIG. 6b while advancing from the position of the opening of the iron shell at the outer circumference of the residual pig iron successively to the center direction of the furnace. However, in conventional work for removal of residual pig iron by blasting, the amount of iron which can be dug out in the direction outside the furnace as a result of a single blast so as to dismantle the residual pig iron is about 1.5m from the outer circumference of the residual pig iron. To reach the center of the residual pig iron, it is necessary to blast the iron a number of times in accordance with the distance to the center of the residual pig iron. Further, the area of the working face becomes larger the further in the direction of the furnace center. To advance the entire working face by 1.5 m distance, a large number of blasting holes have to be bored and blasting operations performed. For this reason, while governed by the amount of residual pig iron, an extremely long time is taken until the completion of removal of residual pig iron. Past figures show that about seven days are required when blasting 300 tons of residual pig iron to split it into small pieces and remove it, while about 14 days are required for 1500 tons of residual pig iron. Further, the method of removal of residual pig iron using blasting was accompanied with danger, so full safety measures were required. Further, when blasting residual pig iron to split it into small pieces, the blast wave at the time of blasting and the flying pieces of residual pig iron etc. damaged the surrounding facilities, so repair of the damaged facilities became necessary. To prevent damage to the surrounding facilities, the iron shell opening for unloading the small pieces of split residual pig iron is set with temporary facilities for preventing pieces from flying out and other large expenses have to be spent for safety measures. Usually, the mantel to be removed is placed around the residual pig iron and made use of as a wall for protecting against flying pieces of iron, but when using the mantle in this way, it is necessary to provide a protective wall for preventing the blasting from damaging the mantle, so again massive costs are required. Further, to secure the safety of nearby workers from blasting work, during the blasting work, the surrounding work was temporarily suspended, workers were evacuated, etc. resulting in an unavoidable loss in time in surrounding work. For example, the time for evacuation of workers in surrounding work due to blasting work was about two hours, that is, starting one hour before the blasting and ending when confirming safety such as checking for unexploded explosives after the end of blasting. When for example blasting 20 times, the workers are repeatedly evacuated with each blast, so the lost time in the surrounding work becomes about 40 hours. DISCLOSURE OF THE INVENTION Therefore, the present invention provides a method of removal of residual pig iron which can split and remove the solidified residual pig iron remaining at the furnace hearth by a wire saw safely in a short time when repairing a blast furnace. The method of removal of residual pig iron of the present invention is a method of removal of residual pig iron pulling out and removing solidified residual pig iron remaining at a furnace hearth from the furnace as split residual pig iron blocks when repairing a blast furnace, characterized by removing a part of an iron shell for pulling out the split residual pig iron blocks, boring a residual pig iron bottom through hole for passing a wire saw in furnace bottom refractories under the residual pig iron, passing a wire saw through the residual pig iron bottom through hole and wrapping this wire saw around the outer circumference of the residual pig iron, running the wire saw and cutting the residual pig iron and furnace bottom refractories in the longitudinal direction to split the iron into a plurality of residual pig iron blocks, and pulling the split residual pig iron blocks out from the furnace. The residual pig iron may be cut by cutting the residual pig iron and furnace bottom refractories in the vertical direction along a splitting line parallel to the pullout direction of the residual pig iron blocks or a splitting line flaring out in the pullout'direction to split the iron into a plurality of blocks or boring a residual pig iron bottom through hole through which a wire saw is passed in a direction perpendicular to the pullout direction of the residual pig iron blocks, cutting the residual pig iron and furnace bottom refractories in the vertical direction along a splitting line in a direction perpendicular to the pullout direction of the residual pig iron blocks to split the iron into two residual pig iron blocks. Further, it is also possible to cut the iron along any number of splitting lines in parallel by a plurality of wire saws. Furthermore, when cutting the residual pig iron, it is also possible to continuously supply cooling fluid to the path over which a wire saw runs so as to cut the iron while cooling the wire saw. Further, when pulling out a residual pig iron block from the furnace, it is possible to place a residual pig iron block unloading trolley or residual pig iron block unloading mount at the side of the residual pig iron block with a top surface level matched with the bottom surface of the residual pig iron block to be pulled out, give a horizontal force to the residual pig iron block to make the residual pig iron block and remaining furnace bottom refractories slide to make the residual pig iron block move laterally in the horizontal direction for pullout and be placed on the residual pig iron block unloading trolley or residual pig iron block unloading mount or possible to jack up a residual pig iron block, place a transport device for carrying the residual pig iron block in the clearance formed between the residual pig iron block and the remaining furnace bottom refractories under the residual pig iron block, jack down the residual pig iron block to place it on the transport device, and make the transport device carrying the residual pig iron block move horizontally to pull the residual pig iron block out from the furnace. The method of removal of residual pig iron of the present invention uses a wire saw to cut the residual pig iron into large residual pig iron blocks and pulls the residual pig iron blocks outside of the furnace, so compared with removing residual pig iron reduced to small pieces by conventional blasting, it is possible to remove the residual pig iron more reliably in a shorter time. Further, the clearance at a cut part of the residual pig iron formed by the wire saw is about 10 mm. The clearance between the residual pig iron blocks after cutting is narrow, but the cut surfaces are smooth. Even when pulling out the residual pig iron of the different blocks, the adjoining blocks will not catch on each other due to surface relief etc. Further, even if the blocks contact each other, since the cut surfaces are smooth, it is possible to easily pull out the residual pig iron blocks. Due to this, it also becomes possible to remove largely split residual pig iron blocks all at once. Note that by making splitting lines flare out so that the width of the residual pig iron block in the pullout direction becomes greater, an extra pullout margin is formed and smooth pullout is possible without any contact between adjoining residual pig iron blocks. Further, the method of removal of residual pig iron according to the present invention cuts the entire cross-section of the residual pig iron by a wire saw, so there is no need to consider the depth of removal of the residual pig iron, which affects the management of the progress in the work in the case of splitting iron into small pieces by blasting, so management of the removal work becomes simple. The method of removal of residual pig iron using a wire saw of the present invention does not involve blasting, so is free from a blast wave and flying pieces of residual pig iron and therefore safe. Further, the costs for temporary facilities such as establishment of protective walls against the same are lightened, so the economic effects are also extremely large. In the present invention, it becomes possible to cut the high heat residual pig iron soon after cooling and solidifying by continuously supplying a cooling fluid to the path over which the wire saw runs to cool the wire saw and thereby shorten the work period. In the method of removal of the present invention, by preparing a plurality of wire saw machines to cut along a large number of surfaces at one time regardless of the number of pieces into which the residual pig iron is to be split, efficient dismantling becomes possible with almost no change in the time for cutting any number of surfaces. When pulling a residual pig iron block to the outside of the furnace, by setting an unloading trolley or'residual pig iron block unloading mount at the side of the residual pig iron block to carry the residual pig iron block or jacking up the residual pig iron block and place the residual pig iron block on a transport device to pull it out of the furnace, unloading of the residual pig iron block becomes easy. BRIEF DESCRIPTION OF THE DRAWINGS FIG. la is a plan view showing the state of removal of an iron shell and an example of the splitting lines of residual pig iron. FIG. Ib is a schematic view showing the state of boring a through hole in the furnace hearth refractory brick. FIG. Ic is a schematic view showing the state of using a wire saw to cut residual pig iron. FIG. Id is a schematic view showing an example of the pullout. FIG. le is a schematic view showing an example of pullout. FIG. 2 is a schematic view of a wire saw. FIG. 3a is a plan view showing a splitting line and pullout direction of residual pig iron of an example. FIG. 3b is a plan view splitting line and pullout direction of residual pig iron of another example. FIG. 4a is a front view showing an example of pulling out a split residual pig iron block. FIG. 4b is a plan view showing an example of pulling out a split residual pig iron block. FIG. 5 is a schematic view showing the state of filling a cut end by mortar. FIG. 6a is an image of residual pig iron removal work by conventional blasting. FIG. 6b is a plan view showing an example of finely splitting residual pig iron by blasting. BEST MODE FOR CARRYING OUT THE INVENTION Examples of the present invention will be explained using the drawings. Example 1 When repairing a blast furnace, as shown in FIG. Ib, the residual pig iron 1 cooled and solidified by the poured water remains on the furnace bottom refractories 2 comprised of a stack of carbon brick etc. The slag 3 remaining at the surface of the residual pig iron 1 is also solidified by cooling and deposits there. The method of removal of residual pig iron according to this example is an example of cutting the residual pig iron by a wire saw to split it into a plurality of blocks and pulling the split residual pig iron blocks outside of the furnace. Below, the steps of the method of removal of the examples will be successively explained with reference to FIGS, la to Id. (1) Removal of Iron Shell As shown in FIG. la, the iron shell 4 is removed at facing positions of the residual pig iron 1 at the bottom of the furnace body to provide iron shell openings 5 at two locations. One iron shell opening 5 becomes the operating side of the wire saw machine 7 where the wire saw 6 enters and leaves. The other opening 5 becomes the side for pulling out a split residual pig iron block la (arrow) and is made a size for pulling out the residual pig iron block la. (2) Boring of Residual Pig Iron Bottom Through Hole As shown in FIG. Ib, to wrap the wire saw 6 around the residual pig iron 1, it is necessary to pass the wire saw 6 below the residual pig iron 1, so a residual pig iron bottom through hole 8 is formed by a boring machine 9 at any level of 'the furnace bottom refractories 2 below the residual pig iron 1. The residual pig iron bottom through hole 8 is for example made a diameter of about 65 mm to enable the wire saw 6 to run through it effortlessly when the outside diameter of the wire saw is about 11 mm. (3) Cutting by Wire Saw A wire saw 6 is widely known. As shown in FIG. 2, beads 6a comprised of an alloy, diamond beads, or other abrasive layers are provided at intervals on a braided metal wire forming a wire rope. The wire rope between the beads is covered by a resin or rubber 6b. In the present invention, as a wire saw, for example, the "Allied Material Product No. EWLS-255" used for the disassembly and repair of subways, buildings, roads, bridges, etc. can be used. The residual pig iron bottom through hole 8, from the viewpoint of preventing clogging of the diamond beads 6a of the wire saw 6, should be bored at a level close to the bottom plate of the furnace hearth under the furnace bottom refractories 2. When using the wire saw 6 to cut only metal, metal sticks to the diamond beads 6a of the wire saw 6, the chain of beads on the wire clogs, and cutting becomes difficult. However, by simultaneously cutting the residual pig iron 1 and furnace bottom refractories 2, good cutting becomes possible without clogging. This is considered to be because the dust of the furnace bottom refractories 2 does not deposit on or stick to the diamond beads 6a, the dust of the residual pig iron I will not deposit on the diamond beads due to such deposition-free dust, and the diamond beads 6a can thereby maintain their function of cutting edges. At the time of cutting, as shown in FIG. Ic, the front end of the wire saw 6 of the wire machine 7 is passed through the residual pig iron bottom through hole 8 bored in the furnace bottom refractories 2 and is wound over the residual pig iron 1 to be wrapped around the residual pig iron'l. Further, the wire saw is run for cutting. At this time, the running speed of the wire saw 6 is preferably in the range of 20 m/sec to 30 m/sec. At a speed of less than 20 m/sec, efficient cutting becomes difficult, while if over 30 m/sec, the rope of the wire saw 6 breaks more often. The residual pig iron 1 is cut by the wire saw 6, as shown in FIG. la, by cutting along the splitting lines 10 parallel to the pullout direction or in the longitudinal direction along the splitting lines 11 flaring out in the pullout direction, preferably the vertical direction, to split it into two or more residual pig iron blocks la. (4) Pullout of Residual Pig Iron Blocks Each split residual pig iron block la is pulled out by providing a through hole Ib in the vertical direction at the pullout side end of the residual pig iron as shown in FIG. Id and FIG. le by core boring, passing the wire 12b through the through hole Ib, and pulling the block out onto a pullout mount 12 by the oil pressure jack 12a. The furnace bottom refractories 2 peel off or crumble and are separated by the large pullout force at the time of pullout. When pulling a residual pig iron block out from the furnace, an unloading trolley or unloading mount is placed at the side of the residual pig iron block with a top surface level at the same level as the bottom surface of the residual pig iron block to be pulled out, a horizontal force is given to the residual pig iron block to make the residual pig iron on the furnace bottom refractories and the furnace bottom refractories slide and make the residual pig iron block move laterally in the horizontal direction to place it on the unloading trolley or the unloading mount for unloading. Table 1 shows a comparison of the removal times of the method of removal using a wire saw according to the present invention and the conventional method of removal by splitting the iron into small parts by blasting. Note, the method of removal by a wire saw according to the present invention is an example of splitting 300 tons of residual pig iron into three and splitting 1500 tons of residual pig iron into five. Table 1 (Table Removed) As shown in Table 1, according to the method of removal of the present invention, the removal time could be greatly shortened compared with the conventional method of removal. Further, due to this shortening, the time for stopping the blast furnace in blast furnace repair was shortened by that amount and the economic effect accompanying production became extremely large. Example 2 This example, as shown in FIGS. 3a and 3b, splits the residual pig iron 1 into two by the splitting line 10 for removal. As shown in FIG. 3a, the iron shell 4 is removed at the position of the residual pig iron 1 to provide an iron shell opening 5 at the side for pulling out the residual pig iron. The iron shell opening 5 opens to a size enabling two split pieces of residual pig iron blocks la to be pulled out. The splitting line 10 of the residual pig iron 1 cut by the wire saw, seen in a plan view, is made the diametrical direction perpendicular to the pullout direction. The residual pig iron 1 is split into two by being cut in the vertical direction along the splitting line. At any level of the furnace bottom refractories 2 below the residual pig iron 1, a residual pig iron bottom through hole 8 for passing the wire saw is bored in the diametrical direction of the furnace perpendicular to the pullout direction. The front end of the wire saw 6 is passed through the residual pig iron bottom through hole 8 bored in the furnace bottom refractories 2 and is wound over the residual pig iron 1 to be wrapped around the residual pig iron 1, then the wire saw is used for cutting the residual pig iron. The split residual pig iron blocks la are pulled outside of the blast furnace in the arrow direction by the wire rope. Note, as shown in FIG. 3b, if removing all of the iron shell around the residual pig iron 1, the residual pig iron blocks la can be pulled out in both directions shown by the arrows or any direction. In this example, the residual pig iron is split into two and pulled out, so this is effective for the case where the amount of residual pig iron is relatively small. Example 3 This example, as shown in FIGS. 4a and 4b, is an example of using a transport device to pull out the residual pig iron blocks. After splitting the residual pig iron by a wire saw, a residual pig iron block la to be pulled out 'is jacked up, a pullout mount 12 is extended below the residual pig iron block la, a slide plate 13 is moved over the pullout mount 12 and placed under the residual pig iron block la, then the block is jacked down to place the residual pig iron block la on the slide plate 13. Next, the slide plate 13 carrying the residual pig iron block la is pulled out and made to slide over the mount 12 by an oil pressure jack 12a in the pullout direction. Note that instead of slide plate 13, it is possible to use a trolley or other transport device. In this example, a split residual pig iron block can be pulled out with less force compared with when peeling off or crumbling and separating the furnace bottom refractories and dragging the block out over the furnace bottom refractories. Example 4 This example is an example enabling cutting of high temperature residual pig iron by cooling the wire saw at the time of cutting by a wire saw. The heat capacity of the residual pig iron cooled and solidified by the water cooling in the furnace is large. Even after the elapse of several days, the residual pig iron temperature is still high. For example, even after the elapse of seven days from the end of water cooling, the temperature of the residual pig iron itself usually becomes a temperature of 600°C or more. On the other hand, the rubber or resin parts of the wire saw in general have heat resistant temperatures of 200°C or less. Since they do not have the heat resistance necessary for cutting the high temperature residual pig iron, cutting the residual pig iron as it is becomes difficult. Therefore, to cut this high heat residual pig iron while securing wire strength, it is possible to extract the heat from the cut cross-section at which the wire contacts the high temperature residual pig iron and the range by which the wire passes through the high temperature parts by continuously supplying cooling water or cooling nitrogen or another cooling fluid while cutting the residual pig iron to thereby cut the residual pig iron by a wire saw. As shown in FIG. 5, by filling the cut end by mortar 14.after starting the cutting, it is possible to efficiently utilize the cooling fluid supplied. INDUSTRIAL APPLICABILITY According to the present invention, the residual pig iron can be split into large residual pig iron blocks using a wire saw and the large blocks can be pulled out from the furnace, so compared with the conventional method of using blasting to finely split the residual pig iron, it is possible to safely and reliably remove the residual pig iron 'in a shorter time, therefore the industrial applicability of the present invention is extremely great. We Claim: 1. A method of removal of residual pig iron pulling out and removing solidified residual pig iron remaining at a furnace hearth from the furnace as split residual pig iron blocks when repairing a blast furnace, said method of removal of residual pig iron characterized by removing a part of an iron shell for pulling out the split residual pig iron blocks, boring a residual pig iron bottom through hole for passing a wire saw in the furnace bottom refractories under the residual pig iron, passing a wire saw through the residual pig iron bottom through hole and wrapping this wire saw around the outer circumference of the residual pig iron, running the wire saw and cutting the residual pig iron and furnace bottom refractories in the longitudinal direction to split the iron into a plurality of residual pig iron blocks, and pulling the split residual pig iron blocks out from the furnace. 2. A method of removal of residual pig iron as set forth in claim 1, characterized by cutting the residual pig iron and furnace bottom refractories in the vertical direction to split the iron into a plurality of blocks along splitting lines parallel to the pullout direction of the residual pig iron blocks or splitting lines flaring out in the pullout direction. 3. A method of removal of residual pig iron as set forth in claim 2, characterized by cutting the iron along any number of splitting lines in parallel by a plurality of wire saws. 4. A method of removal of residual pig iron as set forth in claim 1, characterized by boring a residual pig iron bottom through hole through which a wire saw passes in a direction perpendicular to the pullout direction of a residual pig iron block and cutting the residual pig iron and furnace bottom refractories in a vertical direction along a splitting line in a direction perpendicular to the pullout direction of the residual pig iron block to split the iron into two residual pig iron blocks. 5. A method of removal of residual pig iron as set forth in any one of claims 1 to 4, characterized by, when cutting that residual pig iron, continuously supplying a cooling fluid to the path through which the wire saw runs so as to cut while cooling the wire saw. 6. A method of removal of residual pig iron as set forth in any one of claims 1 to 5, characterized by, when pulling a residual pig iron block outside of the furnace, placing a residual pig iron block unloading trolley or residual pig iron block unloading mount at the side of the residual pig iron block with a top surface level matched with the bottom surface of the residual pig iron block to be pulled out and applying a horizontal force to the residual pig iron block to cause sliding between the residual pig iron block and the remaining furnace bottom refractories to make the residual pig iron block move laterally in the horizontal direction and be pulled out to be placed on the residual pig iron block unloading trolley or residual pig iron block unloading mount. 7. A method of removal of residual pig iron as set forth in any one of claims 1 to 5, characterized by, when pulling a residual pig iron block outside of the furnace, jacking up the residual pig iron block, arranging a transport device carrying a residual pig iron block in the space between the residual pig iron block and the remaining furnace bottom refractories under a residual pig iron block, jacking down the residual pig iron block to place it on a transport device, and making the transport device carrying the residual pig iron block move horizontally to pull the residual pig iron block outside the furnace. 8. A method of removal of residual pig iron substantially such as herein described with reference to foregoing illustrations and accompanying drawings.

Documents:

2229-delnp-2008-Abstract-(05-03-2014).pdf

2229-delnp-2008-Abstract-(15-04-2013).pdf

2229-delnp-2008-abstract.pdf

2229-delnp-2008-Claims-(05-03-2014).pdf

2229-delnp-2008-Claims-(15-04-2013).pdf

2229-delnp-2008-claims.pdf

2229-delnp-2008-correpondence-others.pdf

2229-delnp-2008-Correspondence Others-(16-05-2013).pdf

2229-delnp-2008-Correspondence-Others(15-04-2013).pdf

2229-delnp-2008-Correspondence-Others-(05-03-2014).pdf

2229-delnp-2008-description (complete).pdf

2229-delnp-2008-Drawings-(15-04-2013).pdf

2229-delnp-2008-drawings.pdf

2229-delnp-2008-form-1.pdf

2229-delnp-2008-form-2.pdf

2229-delnp-2008-form-26.pdf

2229-delnp-2008-Form-3-(15-04-2013).pdf

2229-delnp-2008-form-3.pdf

2229-delnp-2008-form-5.pdf

2229-delnp-2008-GPA-(15-04-2013).pdf

2229-delnp-2008-pct-210.pdf

2229-delnp-2008-pct-304.pdf

2229-delnp-2008-pct-308.pdf