Abstract:
A mud gun cap is provided. The mud gun cap includes a flame resistant outer face, a ring and a mounting device wherein the mud gun cap connects to a mud gun nozzle to protect the mud gun nozzle from deterioration because of contact with molten iron and slag. The mud gun cap also prevents, or at least reduces the amount of, mud falling out of the nozzle while the mud gun nozzle is rotated into operation position. In some embodiments, the mud gun cap has a selectively movable circular barrier that at least partially prevents the mixture of mud and iron/slag in the tap hole.

Description:
RELATED APPLICATIONS 
   This application claims all of the benefits of, and priority to, U.S. Provisional Application Ser. No. 60/797,086 filed on May 3, 2006. Application Ser. No. 60/797,086 is also titled Mud Gun Cap and is incorporated herein in its entirety. 

   This invention relates generally to blast furnace iron making operations and more particularly to a cap for the nozzle of a mud gun. 
   BACKGROUND 
   Raw materials, including iron ore, limestone, and coke are added to a blast furnace where they are heated. As the raw materials are heated, molten iron forms at the bottom of the blast furnace and a layer of slag forms on top of the molten iron. After a sufficient volume of molten iron builds up at the bottom of the blast furnace, the blast furnace is tapped to remove the molten iron. A tap drill is used to tap the blast furnace by drilling out the tap hole. As the tap drill is removed, molten iron flows through the tap hole into a trough where it is routed to a waiting rail car. 
   When all of the molten iron is drained out of the blast furnace, or after a desired amount of iron has been drained from the blast furnace, the tap hole is sealed. The tap hole is sealed with a mud gun. An anhydrous mixture, commonly referred to as “mud” or “clay” is loaded into the mud gun. The mud gun rotates from a non-operating or resting position to its operating position. In its operating position the mud gun is positioned so that the nozzle  110  ( FIG. 1 ) of the mud gun (not shown) is aligned with the tap hole  130 . Mud  170  is extruded through the nozzle  110  and forced into the tap hole  130 . The mud  170  forces the residual molten iron  160  and slag  150  that is in the tap hole  130  back inside the furnace  140 . Inevitably, however, not all of the iron  160  and slag  150  is pushed back into the furnace  140  i.e., some of the iron  160  or slag  150  remains in the tap hole  130  and mixes with the mud  170  forming a mud and ore residue  180 . The mud gun nozzle  110  remains in place until the mud  170  dries or cures. After the mud  170  is cured, the mud gun is rotated back away from the blast furnace  140 . 
   The mud and ore residue  180  in the tap hole  130  cause binding and wear on the tap drill (not shown) during the subsequent tapping of the blast furnace  140 . In addition, the mud and ore residue  180  causes the drill to walk resulting in an irregular shaped, or oversized hole. This is undesirable because the size of the drilled hole controls the speed of the flow of molten iron  160  out of the blast furnace. 
   In addition, as the nozzle  110  nears the tap hole  130 , the nozzle  110  comes into contact with the molten iron  130  and slag  150 . Overtime, the tip of the nozzle  110  deteriorates and the mud gun nozzle  110  must be replaced. The deterioration is often referred to as rat toothing, because the lower portion of the nozzle tip which routinely comes into contact with the molten iron  160  is eroded faster than the upper potion of the nozzle tip which occasionally comes into contact with the molten iron. Replacement of the mud gun nozzle  110  is expensive and time consuming. 
   In operation, prior to rotating the mud gun into position to plug the tap hole  130 , the operator ensures that the mud  170  is at the end of the nozzle  110 . Mud  170  at the end of the nozzle  110  prevents molten iron  160  from entering and deteriorating the nozzle  110  when the mud gun is rotated into position. However, as the mud gun rotates into position, mud  170  occasionally falls out of the nozzle  110  and into the trough  120 . The mud  170  contacts the molten iron  160  and slag  150  and creates black smoke. This smoke often results in the environmental protection agency (EPA) issuing a fine to the steel manufacturer. 
   SUMMARY 
   A mud gun cap is provided. The mud gun cap includes a flame resistant outer face, a ring and a mounting device. The mud gun cap connects to a mud gun nozzle and protects the mud gun nozzle from deterioration because of contact with molten iron and slag. The mud gun cap also prevents, or at least reduces the amount of, mud from falling out of the nozzle while the mud gun is rotated into operating position. In some embodiments, the mud gun cap also at least partially prevents the mixture of mud and iron/slag in the tap hole. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
       FIG. 1  (Prior Art) is a cross-section of a blast furnace, a tap hole, a mud gun nozzle and a trough; 
       FIG. 2  is a side perspective view of an embodiment of a mud gun cap; 
       FIG. 3  is another perspective view of the mud gun cap of  FIG. 2  tilted to rest on the side of its ring and outer face; 
       FIG. 4  is an exploded perspective view of an embodiment of a mud gun cap; 
       FIG. 5  is another perspective view of an embodiment of a mud gun cap with its parts in assembled form without an outer face; 
       FIG. 6  is a rear perspective view of the mud gun cap in  FIG. 4 ; 
       FIG. 7  is a side view of a mud gun nozzle having a mud gun cap connected thereto; 
       FIG. 8  is a cross sectional view of a blast a furnace, mud gun nozzle and a mud gun cap with mud injected into the tap hole and the circular barrier progressing through the tap hole; and 
       FIG. 9  is also a cross sectional view of a blast furnace, a mud gun nozzle and a mud gun cap with the mud fully injected and the circular barrier near the end of the tap hole. 
   

   DETAILED DESCRIPTION 
     FIGS. 2 and 3  depict perspective views of an embodiment of a mud gun cap  200 . The mud gun cap  200  includes an outer face  210 , which is made of a flame resistant material, such as, for example a 2600 or 2800 degree Fahrenheit fiber. Outer face  210  is adhered to ring  220 . Outer face  210  may be adhered to ring  220  using any means, such as, for example, glue or staples. The inside diameter  410  and outside diameter  420  of ring  220  ( FIG. 4 ) is approximately the same size as the corresponding inside diameter  710  and outside diameter  720  of the mud gun nozzle  110  ( FIG. 7 ). Ring  220  may be constructed of any material, such as ¾″ particle board or plywood. Preferably, ring  220  is made of a flammable material that will ignite and burn after a certain period of time in contact with molten iron  160 . A mounting device  230  is secured to ring  220 . Mounting device  230  may be any type of device used to secure and position the mud gun cap  200  to a mud gun nozzle  110 . In this embodiment, mounting device  230  is sheet metal formed in a cylindrical shape. The cylindrical sheet metal mounting device  230  has an outside diameter that corresponds roughly to the inside diameter of the mud gun nozzle  110  and the inside diameter of ring  220  as shown in  FIG. 7 . The cylindrical sheet metal mounting device  230  extends approximately an inch past the back surface  610  ( FIG. 6 ) of the ring  220 . The mounting device  230  is secured to ring  220  using any means, such as, for example, brads, screws, nails, glue, an adhesive, etc. Mounting device  230  fits snugly in the end of nozzle  110 . Other mounting devices, such as, a device having two or more pins may be used. 
   Another embodiment of a mud gun cap  400  is shown in  FIG. 4 . This view is an exploded view of the mud gun cap  400 . This embodiment is similar to the embodiment described with respect to  FIGS. 2 and 3 , and numbers that correspond to previously described components are used here for similar components of this embodiment. In addition to the previously described components, mud gun cap  400  includes a circular barrier  240 . Circular barrier  240  is made of a flame resistant material, such as, for example a 2600 or 2800 degree Fahrenheit fiber. Circular barrier  240  has an outside diameter that is approximately the same size as the inside diameter of the mounting device  230  and/or ring  220 . As shown in  FIGS. 5 and 6 , circular barrier  240  is placed inside mounting device  230  up against outer face  210  (not shown in  FIG. 5 ) and is held in place by friction. Optionally, circular barrier  240  may be held in place by other means, such as, for example, an adhesive. 
     FIG. 5  illustrates yet another embodiment of a mud gun cap  500 . Mud gun cap  500  includes ring  210 , mounting means  230  and circular barrier  240 , but does not include outer face  210 . While an outer face may be used, the front surface  500  of ring  220  may be covered instead by a layer of refractory material (not shown). Similar to the outer face, the layer of refractory material provides a flame resistant barrier, and may also be used to temporarily secure circular barrier  240  in place. 
   A mud gun nozzle  110  fitted with a mud gun cap  400  is shown in  FIG. 7 . The mud gun nozzle  110  has an interior surface  710 . Mounting device  230  is fitted into the open end of the mud gun nozzle  110  and the mud gun cap  400  is pushed into place. The mounting device  230  fits snuggly against the interior surface  710 . In addition, mud  170  inside of the mud gun nozzle  110  may also aid in securing the mud gun cap  400  in place through surface tension between the mud  170  and the mounting device  230 . As previously described, mud gun cap  400  also includes outer surface  210 , ring  220  and circular barrier  240 . The mud gun cap  400  seals the end of the mud gun nozzle  110  and prevents mud  170  from falling out of the nozzle  110  and into the trough  120 . 
     FIGS. 8 and 9  illustrate operation of a mud gun (not shown) having a mud gun cap  400  on the mud gun nozzle  110 . The mud gun is rotated into position to plug the tap hole  130  of the blast furnace  140 . As the mud gun is rotated into position, the outer face  210  of mud gun cap  400  comes into contact with the molten iron  160  flowing out of the tap hole  130 . The outer face  210 , which may be 2800 degree Fahrenheit fiber, protects the mud gun cap  400  and the tip of the mud gun nozzle  110 . As a result, use of the mud gun cap  400  extends the life of the mud gun nozzle  110  because the molten iron  160  does not come in contact with the mud gun nozzle  110  and cause deterioration. 
   When the mud gun is rotated into position, the outer face  210  is pressed firmly against the tap hole  130 . The mud gun is activated and forces mud  170  through the nozzle  110 . The pressure exerted by the mud  170  causes the outer face  210  to break or shear off allowing the mud  170  and circular barrier  240  to be forced up into the tap hole  130 . Fractured portions of outer face  210  may fold over and remain secured to mud cap  400  or travel up the tap hole  130  along with the mud  170 . Treatments, such as, for example, perforations, may be used to control the locations of the fractures so that the size and shape of the fractured portions of outer surface  210  are relatively predictable and whether or not the fragments of outer surface  210  remain attached to mud gun cap  400  or travel up the tap  130  along with the mud  170  is also predictable. 
   As the circular barrier  240  is forced up through the tap hole  130  it acts as a barrier between the slag/molten iron  150 / 160  and the mud  170 . In  FIG. 8  the circular barrier is shown about half way up the tap hole  130 . In  FIG. 9  the tap hole  130  is filled with mud  170  and the circular barrier  240  is shown near the end of the tap hole  130 . The circular barrier  240  at least partially prevents slag/molten iron  150 / 160  from remaining in the tap hole  130  and mixing with the mud  170  to form a mud and ore residue  180  (illustrated in  FIG. 1 ). After the mud  170  dries or cures, the mud gun is rotated back into its resting position. The mud gun cap  400  either falls off on its own, or is knocked off by an operator. 
   The material making up the mud gun cap  400  is combustible and/or will melt if it falls off into the trench  120  and comes into prolonged contact with the molten iron  160 . In addition, since the tap hole  130  is now filled with mud  170  and contains less mud and ore residue  180 , the tap hole drill (not shown) has an easier time drilling a clean hole in the tap hole  130  during subsequent tapping operations. This extends the life of the tap drill bit and allows for more precise control over the molten iron  160  flow rate. 
   While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. For example the outer face  210  may be perforated around the inside edge of the ring  220  allowing a cleaner tear as the mud  170  is forced through. Therefore, the invention, in its broader aspects, is not limited to the specific details, the representative apparatus, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant&#39;s general inventive concept.