Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
  • B22D41/02—Linings
  • B22D41/023—Apparatus used for making or repairing linings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D1/00—Casings; Linings; Walls; Roofs
  • F27D1/0003—Linings or walls
  • F27D1/0006—Linings or walls formed from bricks or layers with a particular composition or specific characteristics
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D1/00—Casings; Linings; Walls; Roofs
  • F27D1/16—Making or repairing linings increasing the durability of linings or breaking away linings
  • F27D1/1636—Repairing linings by projecting or spraying refractory materials on the lining
  • F27D1/1642—Repairing linings by projecting or spraying refractory materials on the lining using a gunning apparatus

Definitions

• This invention relates to a gunning method in which basic gunning refractories aresuitably coated or filled to construction, vessel and apparatusfor which a refractory property is required.
• a strong, refractory layer at any place where refractory coating or filling is needed, irrespective of plane, curved surface, concave portion, void portion, and the inner surface or the outer surface of tubular body, not to speak of melting furnaces such as blast furnace, converter, electric furnace and reverberatory furnace, vessels for molten metal such as ladle and tundish, vessels for treating molten metals used in Rheine- tahl-Hereus process and Dortmund Wennmaschinetenunion process, various industrial, heating furnaces, various accessories and accessory positions of all these furnaces and vessels, and appliances and apparatuses used in accompanying working. It is also possible to resolve the problem such as rebound loss or droop.
• the object of the invention is to provide a method for the gunning of a basic gunning refractory in which there is carried out a cold or hot gunning coating or filling, by a nozzle mixing method, of a gunning refractory containing a basic refractory as aggregate, not more than 5 % by weight of at least one of organic fibrous materials and inorganic fibrous materials, and as binder, at least one of phosphates and silicates, characterized in that the gunning refractory is fed to the nozzle portion under air pressures in the range 1 10 kg/cm 2 , said gunning refractory is then discharged while being mixed at said nozzle portion with 5 N 25 % by weight of water having the pressure in the range 0.5,5 Kg/cm 2 and while being accompanied by a rotary motion, the gunning order at the start of discharging takes first air and water simultaneously and then the gunning refractories, and the distance between the nozzle end and the gunn
• the reason of using basic refractories as aggregate of the gunning refractory in effecting the present invention is that not only they are excellent in both refrac- toriness and load softening point but particularly they exhibit an excellent melting-down resistancy against high temperature under the co-existence with basic slag, and as the basic refractories there can be used more than one selected from among magnesia refractories such as magnesia clinker, dolomite, clinker, peridottite, chrome magnesia and magnesia spinel, and lime refractories such as sintered calcia, larnite and quick lime.
• magnesia refractories such as magnesia clinker, dolomite, clinker, peridottite, chrome magnesia and magnesia spinel
• lime refractories such as sintered calcia, larnite and quick lime.
• Organic and inorganic fibrous materials enhance the porosity of the gunning, coating layer, have smaller bulk specific density and improve the spalling resistancy of said coating layer so that at least one of both of them is mixed up to 5 % by weight. Even with the addition thereof by more than 5 % by weight any improved effect is not noticed but to the contrary it degrades the mechanical strength (compressive strength).
• fibrous materials the following can be mentioned.
• animal and vegetation fibers such as pulp, beaten paper, cotton, wool, silk and synthetic fibers, as organic fibrous materials, and heat resistant fibers such as asbestos, rock wool, slag wool, ceramic fibers and carbon fibers, as inorganic fibrous materials.
• Phosphates and silicates used as binder are known as binder for refractory aggregate, and there can be used more than one selected from among alkali metal salts, alkali earth metal salts and aluminium salts or orthophosphoric acid, polyphosphoric acid, methaphosphoric acid and ultraphosphoric acid with regard to phosphates, and from among alkali metals of silicic acid with regard to silicates.
• the gunning refractory is fed to the nozzle portion under air pressures from 1 to 10 Kg/cm2 and discharged while being mixed with water under pressures in the range 0.5.5 Kg/cm 2 and while being accompanied by a rotary motion in said nozzle portion.
• the reason why the gunning refractory is fed under air pressures in the range 1 to 10 Kg/cm is that it is possible to optionally take the mode of discharging ranging from gunning and beating to a condition like flowing-out, and with 1 Kg/cm 2 the air pressure is not sufficient while 10 Kg/cm 2 air pressure is too great whereby neither of the cases can achieve the object of the present invention.
• the gunning order at the time of starting the discharge is brought in such a way that the air and the water are discharged simultaneously and then the gunning refractory is discharged.
• the opening for supplying water in said nozzle portion canbe provided by single or plurarity in optional position and mode in the nozzle portion to effect a nozzle mixing.
• the amount of supplying water is from 5 to 25 % by weight to the gunning refractory, less than 5 % by weight of water is too little to make a complete mixing and to have a sufficient adhesion strenght while more than 25 % by weight is too great so as to flow the gunning refractory away whereby neither of the cases forms a sufficient coating layer.
• the distance from the nozzle to the gunning surface is in the range 0.15 to 1.00 m, and with less than 0.15 m distance the gunning refractory is greatly lost by rebound while if the distance exceeds 1.00 mthe discharging energy is lowered, so that any of such cases does not form a preferable coating layer.
• the reason why the gunning width of the gunning refractory in the gunning surface is less than 1.00 m is that it is related to said distance between the nozzle and the gunning surface, and in case the gunning width is more than 1.00 m it is non longer possible to obtain a useful coating layer.
• the adjustable range of more suitable gunning width is from 0.05 to 1.00 m.
• the angle to the gunning surface of the nozzle may be as near right angle (vertical) as possible, but practically an angle of more than 45 degrees will suffice since it hardly causes rebound and it is almost same as in right angle.
• Said angle of the nozzle can be changed by turning the nozzle arm or curving or bending the tip portion of the nozzle.
• an automatic operation apparatus provided with various functions such as travelling, moving sidewise and vertically and turning.
• the preferable temperature range wherein the present invention can be effected is 0 ⁇ 1,000°C whichever in cold gunning or hot gunning. If it is below 0°C, the gunning freezes and if it exceeds 1,000°C the water content quickly evaporates so that in both cases it becomes difficult to gun the refractory.
• the discharge amount from the nozzle is in the range 5 ⁇ 25 Kg/min, and with less than 5 Kg/min or with 25 kg/min the discharge amount is too little or too much whereby in both the cases gunning becomes impossible.
• the nozzle to the gunning surface can move in one of the optional directions accompanied by reciprocal movement and spiral movement. Naturally a reverse case may occur to the case in which the moving direction of said nozzle accords with the rotational movement direction of said gunning refractory, but in any case the object of the present invention is achievable. It is preferable that the moving speed of the nozzle to the gunning surface is 30 m/min during the gunning, and to be speedier than 30 m/min is too fast so that the adhesion of the gunning refractory becomes incomplete due to the rebounding of the refractory from the gunning surface.
• nozzle employed in the method of this application, it would be preferable to provide at the peripheral edge of the tip air injection ports which form an air curtain at the tip in the gunning direction, so as to prevent the gunning refractory from scattering. Further, to prevent the nozzle from blocking, it would also be preferable that gunning is carried out with a nozzle, at least part of which is provided with a rotational machanism.
• the following is an example in which the present invention was carried out for lining a surface of refractory bricks of a tundish for continuous steel casting.
• a gunning was effected in such manner that a gunning refractory consisting of a mixture of 86 % by weight of magnesia clinker, 4 % by weight of rock wool, 3 % by weight of waste cotton, 4 % by weight of sodium primary phosphate and 3 % by weight of sodium methasilicate, was fed to the nozzle portion under an air pressure of 5.3 Kg/cm 2 from the tangential direction to the cross section of the nozzle, while being supplied 11 % by weight of water of the gunning refractory from the circumferential apertures in said nozzle portion.
• the nozzle Retaining the distance between the nozzle and the gunning surface with 0.4 m and the gunning angle with approximately 90° the nozzle was moved spirally along the inner circumference at the speed of 1 m/min. Morever, the temperature at the gunning surface just before the starting of the gunning was 500°C, when a coating layer of 0.2 m adhesion width was obtained in the discharge amount of 15 Kg/min.
• the gunning refractory was discharged while being mixed with water and being accompanied by a rotary motion, the gunning refractory was adhered uniformay and smoothly to the gunning surface since being subject to a rectifying control by an intermediate squeezing portion, the rebound loss was only 10 % though it was 30 ⁇ 40 % according to conventional method, and droop was not noticed thereby improving the conventional problems.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Furnace Housings, Linings, Walls, And Ceilings (AREA)

Priority Applications (2)

Applications Claiming Priority (1)

Publications (2)

Family

ID=8191482

Family Applications (1)

Country Status (2)

Citations (3)

• 1983
  • 1983-03-30 EP EP19830420059 patent/EP0121029B1/de not_active Expired
  • 1983-03-30 DE DE8383420059T patent/DE3370857D1/de not_active Expired

Patent Citations (3)

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