Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
  • B28B11/00—Apparatus or processes for treating or working the shaped or preshaped articles
  • B28B11/24—Apparatus or processes for treating or working the shaped or preshaped articles for curing, setting or hardening
  • B28B11/243—Setting, e.g. drying, dehydrating or firing ceramic articles
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B3/00—Drying solid materials or objects by processes involving the application of heat
  • F26B3/32—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action
• • 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
  • C04B33/00—Clay-wares
  • C04B33/30—Drying methods
• • 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
  • C04B35/10—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 based on aluminium oxide
  • C04B35/101—Refractories from grain sized mixtures
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B23/00—Heating arrangements
  • F26B23/04—Heating arrangements using electric heating
  • F26B23/06—Heating arrangements using electric heating resistance heating
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B3/00—Drying solid materials or objects by processes involving the application of heat
  • F26B3/32—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action
  • F26B3/34—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action by using electrical effects
  • F26B3/353—Resistance heating, e.g. using the materials or objects to be dried as an electrical resistance

Definitions

• the present invention relates to a process for the drying of objects or bodies containing water and made of a refractory material.
• objects or bodies there are also included such refractory constructions as are constituted by linings of tundishes, the bottom part of ladles, chute furnaces for casting, electric arc fur ⁇ naces, etc.
• the expression also, of course, covers sepa- rate objects or bodies such as bricks, larger constructio ⁇ nal elements of different types of furnaces, lances etc.
• the drying of constructions of refractory materials intended for use in applications requiring a high tempe ⁇ rature requires the water present in the material to be removed in an effective and safe manner.
• the techniques hitherto prevailing are drying while supplying heat from the outside or in some other way.
• drying takes place in furnaces of different types, and when drying linings of different types the heat is supplied also from the outside by the furnace being heated after drying temperature for the purpose of removing the water to a sufficient degree so that the lining can be taken into use.
• the prior art in ⁇ volves substantial draw-backs, such as high energy re- quirement, extended and thereby costly drying, difficul ⁇ ties in determining when the drying is finished, etc.
• Fur ⁇ thermore there are risks involved in connection with the drying while supplying external heat residing in the risk for bursting.
• the water present in the ma- terial will be evaporated under heavy volume increase, and this results in obvious risks to the environment.
• This problem is the foundation of the techniques disclosed in Swedish patents 7315942-8 and 8206043-5, wherein a solu ⁇ tion, is presented residing in the advance inclusion in the material of channel-forming elements or fibres to facili ⁇ tate release of the water in connection with the heating.
• the present invention has for its object to provide new drying techniques, wherein the disadvantages of the prior art are avoided.
• one object of the invention is to provide a new drying process resulting in substan- tially reduced drying costs at the same time as the drying period will be substantially shortened.
• Another object of the invention is to provide a pro ⁇ cess which in its preferred form involves eliminated or at least substantially reduced risk for bursting.
• resistor elements can be arranged in holes or channels in the refractory ma ⁇ terial in different ways.
• the resistor elements can be removable and thus renewed useful or they may be fixed ⁇ ly casted to the material and thus left behind in the ma ⁇ terial after finished drying. It is particularly preferred in the process according to the invention to carry out the drying of objects or bo ⁇ dies made of a refractory material containing channel-for ⁇ ming elements, which are substantially evenly distributed in the material.
• Such channel-forming elements suitably constitute about 0.05 to 0.5% by weight of the material, and a particularly preferred range is about 0.1 to 0.3% by weight.
• Preferred channel-forming elements are based on natu- ral materials originating from plants, such as for example straw or stalks from ordinary cereals, grass, rice roots, fibres from palm trees, needles from pine trees and simi ⁇ lar.
• the diameter of said channel-forming elements can vary from some microns up to several milli ⁇ meters.
• palm tree fibres are preferred, since such fibres have a small diameter, a high density and are relatively rigid. This type of fibre is often sold under the tradename "Bassine".
• Alternative materials for the channel-forming ele ⁇ ments are pre-fabricated fibres made of suitable plastic materials, such as polypropylen.
• Such materials or ele ⁇ ments may have a diameter of from some tens of microns up to a few millimeters, for example up to about 5 mm.
• the channel-forming elements are elongate, i.e. have high ratio length/diameter. Said ratio is suitably above about 5 and the length of the elements may vary within broad limits. In order to facilitate admixing these elements into the refractory material it is preferred that the length has not too high a value.
• Zr0 2 may be used, and also neutral refractory compositions containing mainly Al ⁇ O, or Cr ⁇ O or a basic refractory mixture containing essentially MgO or CaO, can be used when applying the techniques according to the present in- vention.
• the refractory oxide constitutes the major part of the material and the weight ratio thereof suitably lies within the range about 75 to about 95% by weight of the material as a whole. It may also contain a minor amount of binder such as high grade aluminumoxide cement, phosphoric acid or clay.
• the refractory material used in the drying process according to the invention is prepared in a conventional manner by mixing of the constituents, such as in a mixing container containing a mixer, and the container can be heated if desirable, and when used the channel-forming elements are introduced into the material during some phase of its manufacture.
• Example 2 refers to the appended drawing which in two different views shows the design of a block for a foundry.
• the present example relates to drying in accordance with the present invention of a so called injection lance intended for the feeding of gas or other material into a molten metal.
• the lance consists of a central steel tube surrounded by a mantle made of a refractory material, in the present example Victor Korund WR, H ⁇ gan ⁇ s, Sweden.
• This refractory material has a composition of 96% 1 2 0 3 , 0.5% Si0 2 and 0.1% Fe-Og.
• the apparent density according to Din 51065 is 2.800 kg per m3.
• the quantity of refractory material in the lance is about 330 kg.
• the re ⁇ fractory material contains evenly distributed palm tree fibres of the type Bassine having a length varying from about 15 to about 20 mm.
• the fibres constitute about 0.2% of the refractory material.
• Drying takes place by introdu- cing an elongate electric resistor element in the center of the steel tube and energy is supplied at a power of about 3 KW.
• the drying time is about 24 hours, and no signs of bursting or other problems could be observed during drying.
• a normal drying time for such a lance in a furnace while supplying external heat is multifariously longer and normally requires three days or more.
• addi ⁇ tion to the advantage of short drying time there is also, of course, obtained the advantage of substantially lower energy consumption, since the energy losses to the envi ⁇ ronment are substantially reduced.
• the present invention relates to the manufacture and drying of a block for a foundry, the block having the de ⁇ sign as is clear from the drawing.
• the block is made of a refractory material, Ultracast CD 4 SR, Bohlin & LOfgren, Sweden, and its weight is about 1.350 kg.
• the refractory material contains channel-forming fibres in the same man- ner as stated in Example 1. In connection with casting 14 through-going holes having a diameter of about 20 mm even ⁇ ly distributed over the block are arranged.
• the drying takes place by insertion of electric re ⁇ sistor elements in tubular form, one into each hole, and an added power of 12 KW is supplied for the drying.
• the drying time is about 12 hours for the complete removal of contained water.
• the present example relates to the drying of a so called heart body for an LB-furnace.
• the heart body is cast starting from Victor Korund ES, Hoganas, Sweden, as a refractory material and the quantity of the material is 750 kg.
• the chemical analysis for the refractory material is 94% A1 2 0 3 , 0.5% Si0 2 and 0.1% Fe 2 C* 3 . Its apparent den- 3 sity according to Din 51065 is 2.750 kg per m .
• the ma ⁇ terial is supplied with channel-forming fibres in the sam way as in Example 1. In connection with the casting there are arranged 12 through-going holes in the heart body in- tended for electric resistor elements.
• the present invention is not limited to the embodiments illustrated above.
• the process according to the invention can be applied to the drying of refractory masses irrespective of shape and device. Even if the examples relate to the drying of self-supported bodies or objects the invention may equally well be applied to permanent refractory constructions, such as furnace linings and the like. The drying can take place using ' reusable electric resistor elements or using resis- tor elements permanently cast into the material.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Microbiology (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structural Engineering (AREA)
• Biomedical Technology (AREA)
• Molecular Biology (AREA)
• Health & Medical Sciences (AREA)
• Biotechnology (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Dispersion Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Sustainable Development (AREA)
• Drying Of Solid Materials (AREA)
• Compositions Of Oxide Ceramics (AREA)
• Ceramic Products (AREA)
• Furnace Housings, Linings, Walls, And Ceilings (AREA)

Priority Applications (8)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20383691

Family Applications (1)

Country Status (9)

Citations (3)

• 1991
  • 1991-09-11 SE SE9102625A patent/SE469093B/sv not_active IP Right Cessation
• 1992
  • 1992-09-11 AU AU25784/92A patent/AU660715B2/en not_active Expired - Fee Related
  • 1992-09-11 EP EP92919822A patent/EP0603297A1/en not_active Ceased
  • 1992-09-11 CA CA002118790A patent/CA2118790A1/en not_active Abandoned
  • 1992-09-11 JP JP5504729A patent/JPH07500900A/ja active Pending
  • 1992-09-11 KR KR1019940700804A patent/KR940702604A/ko not_active Application Discontinuation
  • 1992-09-11 BR BR9206480A patent/BR9206480A/pt not_active IP Right Cessation
  • 1992-09-11 WO PCT/SE1992/000628 patent/WO1993005354A1/en not_active Application Discontinuation
• 1994
  • 1994-03-10 FI FI941140A patent/FI941140A0/sv not_active Application Discontinuation

Patent Citations (3)

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