Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/013—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics containing carbon
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/66—Monolithic refractories or refractory mortars, including those whether or not containing clay

Definitions

• the invention relates to a method for the production of a pan locking stone for metallurgical pans consisting of a refractory refractory concrete or a corresponding pan closure block.
• Refractory ladle closures are produced according to the prior art by pouring, for example, a hydraulically setting refractory concrete into a mold or as a compact. You will e.g. used as slide plates in steel pans and used to open and close the metallurgical vessel. For this purpose, the corresponding surface of the sealing stone must be able to slide at the outlet opening of the pan in order to ensure that the outlet opening is securely opened and closed.
• Such a slide closure is e.g. known from DE-PS 26 24 299.
• a refractory concrete which after a fire has a relatively high cold compressive strength of at least 7 x 10 Pa.
• Such unbreakable types of concrete can, however, be admixed e.g. problems with soot, pitch or graphite as lubricants in the manufacture. Since soaking the known capstones in tar, for example, due to the inevitably low porosity which is given with such high-strength refractory concrete types, does not lead to the required depth of penetration of the carbon carrier into the refractory concrete, such have occurred Slide closures cannot be enforced in practice.
• the incorporation of carbon into the structure of e.g. Magnesia, dolomite or bauxite refractory compacts improve the service life.
• Such compacts are therefore impregnated with organic carbon carriers in a pressure impregnation process. Compared to tar-soaked stones, they have an extended service life and improved corrosion resistance to slag or aggressive gases.
• the object of the invention is to create a method for producing a pan closure block for metallurgical pans consisting of a refractory concrete, in which on the one hand the carbon can be built into the concrete structure with a sufficiently large depth of penetration and on the other hand higher thermal expansions in the sealing surface area without I can destroy the cap.
• the process features described make it possible for the first time to use refractory refractory concrete for the production of refractory ladle sealing blocks, in the structure of which carbon can be built in with sufficient depth of penetration by means of pressure impregnation.
• the ring inserted into the casting mold before pouring surprisingly at the same time achieves that substantially higher thermal stresses can be compensated for without the occurrence of cracks, so that a sealing block with excellent sealing properties and a longer service life can be produced.
• the blank is subjected to a vacuum treatment during or after pouring the pasty refractory concrete.
• gas bubbles enclosed in the still pasty concrete mass can escape to the outside, and capillaries or pores can be produced in this way, by means of which the carbon carrier can further penetrate into the concrete mass during subsequent pressure impregnation.
• the casting mold is first filled with the pasty concrete only in the bottom area.
• the casting mold sits on a smooth surface on which the refractory concrete is poured, so that the later sliding surfaces are created with good flatness in this area. Since the underside of the inserted ring lies flush on the bottom of the casting mold, the flatness is not impaired by the inserted ring. Due to the compaction of the material according to the invention, for example by vibration, the poured mass is compressed and prevents larger cavities from forming inside.
• a central core is inserted into the mold, which forms the later outlet channel in the finished slide cap.
• a sheet metal jacket which acts as lost formwork is preferably used as the casting mold in the production method according to the invention.
• the mold blank with the cast ring is transported to a drying chamber and dried there under the application of heat.
• the drying process increases the strength of the raw body.
• the slide closure can be transported without problems and is stored, for example, in an autoclave for carrying out the pressure impregnation.
• the pressure impregnation itself is carried out in a manner known per se.
• the autoclave can be evacuated using a vacuum pump, so that the blanks are degassed. In this way, the existing pores or capillaries are prepared for impregnation with the carbon carrier.
• the carbon-containing impregnation liquid is speed, e.g. a liquid phenol resin solution. This can be done in a simple manner in that the autoclave is connected via a riser to a storage container which contains the impregnation liquid. Due to the negative pressure prevailing in the autoclave, the liquid can penetrate into the autoclave without additional pumps and flood the raw stones stored in it.
• the riser is closed by a valve and the autoclave is pressurized via a pressure line. This makes it easier for impregnating liquid to penetrate into the fine pores or capillaries that open onto the surface of the refractory concrete.
• a treatment time which can be several hours depending on the porosity of the concrete used, the riser to the storage container is opened and the impregnation liquid is conveyed back into the storage container by the excess pressure in the autoclave. Again, no additional pumps are required for this, so that the overall cost of impregnation can be kept extremely low.
• the impregnated closures are subjected to a heat treatment in an oven.
• the aim of this heat treatment is to crack the impregnation liquid absorbed by the refractory concrete.
• the impregnation solution with the elimination of solid carbon, breaks down into gaseous constituents which pass into the furnace atmosphere. With the phenol-resin mixture used, these gases are flammable, so that the atmosphere in the furnace must be reduced. This also prevents the carbon deposited in the pores of the concrete body from being oxidized to form carbon monoxide or carbon dioxide.
• different cracking temperatures which can be between 300 and 1200 ° C., must be used in the furnace. For cracking of carbon enstoffehrs plays next to the temperature itself ⁇ course, the dwell time of the moldings a corresponding role.
• the slide closures produced can be used, with the sliding surface or the lower surface of the ring possibly having to be reground so that a reliable function when opening and closing the outlet opening of the pan is guaranteed.
• pan sealing blocks produced are preferably adjusted by the initial mixing ratio of the refractory concrete so that after a fire at approximately 1400 ° C. they have a maximum cold pressure strength of 7 x 10 Pa. In contrast to higher slugs, these slide closures have
• the mechanical and sliding properties or the penetration depth of the carbon into the prefabricated ring play only a subordinate role in the production process described, since the ring is only intended to absorb the thermal expansion in the out-channel and thus its geometric dimensions are comparatively small can be held.
• the prefabricated rings used are preferably rings with an inner diameter of 50-180 mm, a thickness of 10-60 mm and a wall thickness of 10-60 mm, so that the good sliding properties and service life of the sealing surfaces are not impaired.
• the fact that the mold for the pan closure serves as lost formwork means that the slide can be produced easily and inexpensively without special molds.
• the casting cores used to form the subsequent Abi on the connecting piece are removed in a known manner after the refractory material has set.
• the slide plate according to the invention can be completely recycled after its application.
• the sheet metal jacket is separated from the refractory material, the concrete is ground and added to a new mixture, while the metal can be melted. There is no waste.
• the molded blank is dried after casting at temperatures between 200 and 800 ° C.
• the autoclave provided as the impregnation chamber can preferably be subjected to negative pressure and positive pressure.
• the impregnation liquid can easily be introduced into the autoclave via a riser from a storage container and can be conveyed back after the pressure impregnation has ended.
• no additional feed pumps are required, which would represent a considerable additional effort.
• the porosity of the pan closures is preferably adjusted so that it is between 10 and 60% of its volume.
• the specific weight of the dried blanks can be between 0.2 and 3.2 kg / dm 3 .
• the invention is illustrated in the drawing, for example, and is explained in detail below with reference to the drawing. Show it
• Figure 1 shows a section through a mold for a Pfannenverschl ußstei n
• FIG. 2 shows a schematic process diagram for the impregnation of such slide closures.
• the casting mold 1 shown in a section in FIG. 1 consists of a sheet metal jacket 2, into which pasty refractory refractory concrete is poured through the upper opening 3. After solidification of the set refractory concrete, the sheet metal jacket 2 serves as a lost form, so that no separate casting molds are required.
• a core 5 is inserted, which is removed after the refractory concrete 4 has set, so that an outlet channel 6 is formed for the flowing liquid metal.
• the bottom of the casting mold 1 7 is placed on a very smooth, e.g. hard chrome-plated, possibly ground pad 8 placed.
• the base 8 lies on a vibrating table, not shown, so that the refractory concrete 4 can be vibrated and compressed within the sheet metal jacket 2.
• a prefabricated ring 9 is placed concentrically around the core 5 in the casting mold 1 before the refractory concrete 4 is poured in such that its underside 10 is flush with the base 8 1.
• the casting mold 1 is vibrated by the vibrating table and the refractory concrete 4 is compacted.
• a negative pressure is generated, which leads to degassing the first poured layer 13 of the refractory concrete 4 and the formation of pores or capillaries.
• the sliding surface 14 which forms on the base 8 is in later use of the slide closure against the outlet opening of the pan and can open or close it by a lateral movement.
• FIG. 2 An impregnation system according to the invention for impregnating the dried pan closure parts is shown.
• the system consists of an autoclave 15, which is operated by a vacuum pump
• the 16 can be subjected to negative pressure by means of a line 17.
• the line 17 can be shut off via the valve 18.
• the autoclave 15 is connected via a further line 19 to a pressure vessel 20, which is supplied with compressed air via a pressure pump (not shown).
• the line 19 can also be shut off by a valve 21.
• a riser 23 which can be shut off by a valve 22 and through which it is connected to a storage container 24 which contains the impregnation liquid.
• the locking stones located in the interior of the autoclave 15 can be subjected to any desired overpressure or underpressure in this way.
• valve 22 If the valve 22 is opened when the vacuum prevails in the autoclave 15, impregnation liquid flows automatically from the storage container 24 into the autoclave 15 and floods the capstones stacked in it. Corresponding recovery of the impregnation liquid takes place in a simple manner by opening the valve 21 and pressurizing the autoclave 15 with compressed air. When the valve 22 is open and the valve 18 is closed, the carbon-containing impregnating agent can be conveyed back into the reservoir 24 in this way.
• furnaces provided for drying the molded parts or for heat treatment for cracking the impregnating agent are dispensed with, since these units are designed as conventional drying chambers or kilns and are sufficiently known.
• the Pfannenverschl ußstei ne or their transport to the individual treatment units can be done manually, of course, the individual manufacturing steps can also be automated by using appropriate conveying or loading devices.
• the control of the individual treatment units with regard to pressure, temperature and dwell time can also take place automatically via programmable control units.
• Mold sheet metal jacket Upper opening refractory concrete Core outlet channel Bottom pad Ring bottom side Outer circumferential surface Top layer Sliding surface Autoclave Vacuum pump Line Valve Line Pressure boiler Valve Valve riser Supply container

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Casting Support Devices, Ladles, And Melt Control Thereby (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=6888474

Family Applications (1)

Country Status (4)

Family Cites Families (4)

• 1993
  • 1993-09-15 WO PCT/DE1993/000879 patent/WO1995007781A1/de not_active Ceased
  • 1993-09-15 EP EP93919011A patent/EP0790874A1/de not_active Withdrawn
  • 1993-09-15 AU AU49444/93A patent/AU4944493A/en not_active Abandoned
• 1995
  • 1995-03-08 TW TW084102181A patent/TW269650B/zh active

Non-Patent Citations (1)

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