Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B7/00—Blast furnaces
  • C21B7/12—Opening or sealing the tap holes
  • C21B7/125—Refractory plugging mass
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B7/00—Blast furnaces

Definitions

• This invention relates to anhydrous plugs for stopping the tapholes of blast furnaces.
• This plug comprises, as a basic refractory material, a mixture consisting of low alumina pure silica and one or more refractory or gritty clays,
• a binder a resin or a plastic material containing a setting retarder such that the plug be heat stable at about 200 C.
• This invention relates to the manufacture of anhydrous masses or plugs for stopping the tapholes of blast furnaces.
• anhydrous stopping plugs consist as a rule of a mass or paste made of 20 percent of coking plant tar, percent of powdered coke or coal and 70 percent of an aggregate of refractory materials, these powders being ground to a suitable mesh size, well known to manufacturers; the resulting masses became extremely hard after firing so that the tapholes were no more worn away by the outflowing cast iron. Thus, it was no longer necessary to slow down the blast furnace operation at each casting, whereby a substantial gain was achieved in the daily production.
• the coking operation necessary for hardening the plug material makes it necessary to insert a stopper gun for a period of about 1 hour into the taphole; the space thus occupied in front of the blast furnace and in the main clay-lined trough or runner is particularly detrimental to the blast furnace operators or casters who are confronted with the difficult task of cleaning and repairing this trough or runner between successive castings.
• the time available for allowing the paste located inside the blast furnace to be fired completely is too short and when the plug is removed clots of unfired tar appear which produce flames thrown at relatively great distances, and likely to injure the men working on the front area of the blast furnace.
• the plug mass hardens at a very fast rate in the taphole and therefore the plugger can be withdrawn from the taphole 10 to 15 minutes after the plugging. Under these conditions, the works for reconditioning the casting trough or channel can be carried out more easily. In certain cases the gain of time permits a reduction of the number of men comprising the casting crew.
• the cleaning of this gun is much easier for the men entrusted with this task.
• the smell released from this paste is particularly light and cannot cause discomfort to the crew.
• the use of a binder in the plug mass improves the plasticity of the mass mixed with tars. Therefore, the improved mass according to this invention can be thrusted into the taphole by using taphole-plugging units of lower power rating, thereby enabling smaller concerns or plants to avoid the cost of powerful and therefore very costly plugging machines.
• the improved quick-hardening mass according to this invention is adaptable to the crucible of the blast furnace and constitutes a perfect lining for the internal wall of the crucible. Due to its quick-setting and high-hardness properties, it eliminates cast-iron infiltrations sometimes found after 40- inch to 45-inch drilling, which make drilling operations particularly difficult and costly due to the frequent breakage of drills.
• the first feature characterizing this invention consists in using, as a basic refractory material, a mixture consisting of pure silica (quartz sand) having a very low alumina content (not in excess of 3 to 4 percent) and of one or a plurality of refractory or gritty clays.
• the alumina content of the mixture is selected to keep the silica/alumina ratio as remote as possible from values likely to promote the development of an eutectic structure.
• Silica was the preferential choice because this material expands and tends to offset the shrinking of clay. As the mass hardens it adheres strongly to the walls of the taphole without producing cracks therein. On the other hand, as the absorption power of silica is very low, a lower amount of binder is required to produce a quick-setting plastic paste.
• this material is commonly referred to as a natural or synthetic resin (or) plastic material, and is thermosetting
• This organic material acts as a fluidizer and homogenizer during the manufacture of the plug mass. It also acts subsidiarily as a quickhardener during the plugging operation proper when, by heat conductibility, the heat gradually spreads through the plug mass, and furthermore this organic material promotes the setting of the plug mass within about to minutes.
• plug masses thus prepared had all the requisite properties of first quality taphole plugs at the first application, but as these masses are reconditioned the tapholes lost more and more their original tightness and eventually the plugs became unsuitable for properly sealing the taphole.
• the other feature characterizing this invention consists in utilizing as a binder-hardening substance a resin and a settingretarding agent such that the product be heat stable at about 200 C.
• the resin may be selected from the group comprising phenoplasts and aminoplasts.
• the anhydrous mass may further include materials selected from the group consisting of polyvinyl chloride, benzyl alcohol, and tricresyl phosphate.
• the binder pH value should range from 6 to 7.4.
• the paste can be used with the maximum safety and under practical operating conditions, thus affording considerable savings of material, labor and time.
• the basic materials such as the quartz sand and the heat stable adjuvant afford a competitive cost, and furthermore the amount of mass to be introduced into the taphole is reduced by one-half in relation to conventional masses.
• Refractory material 68% (34% sand, 18% clay) Coke over tar l 1% Liquid tar l7% Resol-type phenol resin 3.5%
• anhydrous mass for plugging blast-furnace tapholes comprising refractory clay and silica sand with tar as a hinder
• the improvement which comprises including in said mass approximately 2 percent to 5 percent of a thermosetting resin selected from the group consisting of phenoplasts and aminoplasts and heat stable at 200 C. and a material selected from the group consisting of polyvinyl chloride, benzyl al cohol, and tricresyl phosphate, said sand containing not more than 4 percent of alumina.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Ceramic Products (AREA)
• Mold Materials And Core Materials (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=8634009

Family Applications (1)

Country Status (7)

Cited By (8)

Families Citing this family (5)

Family Cites Families (1)

• 1967
  • 1967-06-28 FR FR112264A patent/FR1535664A/fr not_active Expired
  • 1967-08-01 US US657499A patent/US3607809A/en not_active Expired - Lifetime
  • 1967-08-02 BE BE702208D patent/BE702208A/xx not_active IP Right Cessation
  • 1967-08-02 GB GB35531/67A patent/GB1189200A/en not_active Expired
  • 1967-12-22 DE DE1583172A patent/DE1583172C2/de not_active Expired
• 1968
  • 1968-04-30 LU LU56000D patent/LU56000A1/xx unknown
  • 1968-06-28 NL NL6809217A patent/NL6809217A/xx unknown

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