CA1105061A - Mortar for repairing damaged portion of blast furnace and mortar charging means - Google Patents

Abstract

MORTAR FOR REPAIRING DAMAGED PORTION OF BLAST FURNACE AND
MORTAR CHARGING MEANS

Abstract of the Disclosure For repairing damaged portion of a blast furnace, mortar composed of 5 to 30% of pitch with a softening point of 70 to 250°C, added as binder, 8 to 50% of ethylene bottom oil added as fluidity imparting agent and, if necessary, less than 3% of pitch, 1 to 7% of phenol resin and less than 10% of metal or carbon fiber, the rest being powdery refractory base materials, is used.
Such mortar is charged under pressure by a charging means, with which the mortar is charged under high pressure by a charging member secured to a plurality of support rods extending from one end of a nozzle penetrating the blast furnace wall.
This charging member functions to guide mortar toward the inner furnace wall by virture of a central projection projecting from its back side.

Description

: This invention relates to mortar for repairing damaged ¦portion of a blas-t fu.rnace and a mortar charging means.
More specifically, the invention concerns mortar, which ~permits repair of the damaged portion of the refractory of the ~furnace wall withou.t interrupting -the operation of the furnace7 .
¦and also a means for chargi~g su.ch mortar.
25 ¦ The refractorles as the lining of the blast furnace are damaged by the descendi~g of bu.rden, their reaction therewith under high -temperatures or their contact with pig iron, and .. particularly su.ch wall portions o~ the Purnace as shaft lower portion, belly and bosh suffer damage either locally or over a 3o wide region in couple o~ years of the du.ty service.
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Once damage to these refractories -takes place, it ren.ders the furnace skin red hot or gives rise to cracks~ Therefore, in such case it has hitherto been in practice to make a repair by charging a refractory material into -the damaged portion so as to artificially form a pro-tec-tive furnace wall on the inner side of -the furnace skin as the ~urnace wall protective measu.re.
As the refractory material, that is, repairing material, which are u.sed today, a refractory material is used as the base material, and sodiu.m silicate, aluminum phosphate, alumina cement, etc. are added as binder. This mixture is kneeded together with 10 -to 30% of water added as flu.idity impar-ting agent to obtain a slurry capable of being forced ou.t from a pump for u.se~ In this case, the addition of water does not only give flu.idi-ty to the material for forcing out from the pu.mp bu.t also has an end of providing for curing or hardening reactions of the blnder~
Meanwhile, as to the fu.rnace skin protection measu.re it is thou.ght necessary for the repairing material charged from a pu.mp via a nozzle into the fu.rnace interior to firmly adhere to the fu.rnace inner wall and thereby form the ~urnace wall.
However, althou.gh -the repairing material of the above com-position containing binders which harden by the hydration . reaction can achleve -the intended end by firmly adhering to ; the fu.rnace skin at normal temperatu.res lower -than 200C, it does not adhere to the furnace skin at temperatu.res above 200C
at all.
This is due to -the fact that water is added as fluidity : imparting agent to the repairing material; more par-ticu.larly, when thi~ repairing material i~ brought into contact with the fu.rnace skin at high temperatures a~ove 200C, the inner sur~ace . - 2 -:

of the furnace skin is momentarily covered with steam, which act to obstruct the adherencé of the repair.ing material to the furnace skin.
When damage to the furnace wall refractory is caused in the blast furnace under service, the furnace skin tem-perature is increased to 300C or above. In this case, it has been in practice to positively lower the furnace skin temperature to a low temperature below 200C by blowing such inactive gas as N2 or steam into the furnace for the purpose of forming the furnace wall by charging the .:
afore mentioned repairing material.
This method, however, causes undesired cooling of the furnace and thus extremely deteriorates the heat balanceO ..
To overcome this drawback inherent in the prior-art repair material, the~applicant has developed a repairing material as disclosed in Japanese Patent Application No. 134192/1973 (laid open for inspection on July 8, 1975 under the num-ber JA-OS 84613/50) and Japanese Patent Application No.
14713/1974 ~laid open for inspection on September 29, 1975 under the number JA-OS 123501/50), which uses a base material mainly composed of a powdery reEractory material and contains solid bituminous materials added as binder and also liquid oil added as fluidity imparting agent.
When this repairing material is charged into the furnace slcin, the bituminous materials contained as binder are fused so as to cover the base material and make the same adhere to the furnace skin even at furnace skin temperatures above 200C. At this time, the binder and liquid oil as the fluidity imparting agent are partly burnt, but a major proportion is carbonized due to re-ducing gases within the furnace and remains as carbon.

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This residual carbon has the Eun~tion of improving the repairing material.
Although this repairing mortar provides an improve-ment over the prior-art mortar such that it can adhere to the furnace skin at temperatures above 200C, it still presents some problems when ma~.ing repair of the upper portion of the blast furnace bosh or local hot red portion; for example, the mortar flows and spreads to enter the bosh so as to have adverse effects upon the operation or prevent sufficient adherence from being obtained. More particularly~ this mortar is in the form of a slurry containing a great deal of liquid, so that when it i5 charged into the blast furnace inner wall by means of a pump it is likely to flow away or embroil coke and other furnace burden as it adheres to the furnace wall. Thus, sufficient repair cannot be expected in such case. In the meantime no device for charging mortar of low fluidity has hitherto been developed.
An object to the invention is to solve the above problems and provide a mortar which is suitable for the repair of damaged portions of the blast Eurnace and also a mortar charging means.
According to the invention there is provided a mortar to be used for repairing damaged portions of blast furnace inner walls, said mortar containing 5 to 30% of pitch with a softening point of 70 to 250C incorporated as binder, and 8 to 50% of ethylene bottom oil incorporated as fluid-ity imparting agent, the rèst being a powdery refractory base material, and said ethylene bottom oil being the residue obtained when refining ethylene from naphtha.
An advantage of the invention, at least in preferred :

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forms, is that it can provide a mortar of high viscosity and which will not readily flow away.
A further advantaye of the invention, at least in prefer~ed forms, is that it can provide a blast furnace repair mortar, which has high hardening speed and permits high mechanical strength to be obtained after hardening.
A still further advantage of the invention, at least in preferred forms, is that it can provide a blast fur-nace repair mortar, which permits sufficient mechanical strength to be obtained in either low temperature or high temperature repair conditions.
A yet further advantage of the invention, at least in preferred forms, is that it can provide a mortar charying means, which lS suited to force out high viscosity mortar under high pre~ssure into a blast furnace during the operation thereof and charying it into the damaged portions of the furnace wall for repairing the same without causing its loss by flowing.
When the pitch proportion is less than 5%, the effect of binding the base material is insufficient, whereas with a proportion greater than 30~ the residual c~rbon after the hardening is excessive to reduce the mechanical strength. In particular, the mortar accordiny to the invention is proved satisfactory in case when mortar of high viscosity and high strength is required particularly for the repair of bosh upper portion or local red hot portion. As the pitch it is possible to use either coal pitch (i.e. r tar pitch) with a sotening point of 60 to 110C or petroleum pitch with a softening point of 160 to 3n 250C or a mixture of these pitches. More particularly, it is desirable to use the coal pitch and petroleum pitch .
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by experimentarily determining their optimum proportions depending upon the -temperature of the repair portions, such as using a great,quantity of coal pitch for the repair of a furnace wall where the skin surface is at a relatively low temperature and using a great quantity of petroleum pitch for the repair of a furnace wall where the skin surface is at a relatively high temperature.
Another feature of the invention resides in the use of ethylene bottom oil as the fluidity imparting agent.
Ethylene bottom oil is obtained as the residue when re-fining ethylene from naphtha and contains a great quantity ~ `
of aromatic compounds, so that under a high temperature reducing atmosphere such as the blast furnace interior it is decomposed to produce residual , , . .
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carbon. Since the residual carbon binds the refractory base ma-terial to form a dense network, extremely strong state o~
bonding can be obtained compared with the carbon bond by pitch or l the like, while also increasing the speed of solidification o~
~mor-tar. Thus, according to the inventi.on 8% or more of ethylene bottom oil is incorporated to accelerate the curing of the repairing mortar and also to increase the mechanical strength thereo~. However7 incoporation of more than 50% of ethylene bottom oil is very unsatisfactory from the standpoints of excessive fluidi-ty and cost. Particularly7 it is experimentarily confirmed that i-t is preferable to incorporate 10 to 15% of ethylene bottom oil in case o~ -the repair of bosh upper por-tion and local red hot portions of the blast fu.rnace and also where ~ loss of mortar by .flowing is undesired while also requ.iring high mechanical s-trength and high curing speed.
¦ In lieu. of a part of the ethylene bottom oil as the fluidity imparting agen~, heavy oil may be used. By so doing, the cu.ring of mortar in a low temperature range can be facilitateda In particular, the conten-t of heavy oil is restric-ted to be less thab 3% when mortar of high viscosity is required as in the case I ¦ of repairing bosh upper portion or local red hot portions.
¦ Examples o:E the powdery refractory base material -that is u.sed are mu.llite (3A1203 2SiO2), sillimanite (A1203 SiO2), ¦kaolin, corundum (A1203), periclase (MgO) and chromite (FeO Cr20~, .
l The grain size of the ~ase material has influence upon the ¦workability of mortar at the time of chargingt so -tha-t i-t is ~ ¦ desira~le:to su.itably select the grain size depending upon the ~specifications of the ~harging apparatu.s to be u.sed. An example ., lis: :
14 ~o 35 mesh size : 10 to 20%

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35 to 200 mesh size : 20 -to 35%
200 and less mesh size : 45 to 60%
In order to accelerate -the hardening of mortar in a low ~temperature range, the mortar -to be used according to the inven-¦tion ma~ contain 1 to 7% of phenol resin. The pheno] resin may ~be these of which thermo-setting temperature is lower than about 200C~ and it is suitably selected depending upon the temperature of the place of repair. However, use of phenol resin in excess ~of 7% is not desired since it deteriorates the strength of the whole mortar after curing.
Further, the mortar to used according to the invention may contain less than 10% of metal fiber or carbon fiber for improvin~ ;
the mechanical strength. The metal fiber or carbon fiber has l the effect of binding the base materlal in the form of a network ¦ to thereby increase the mechanical strength of the ma-terial.
However, its use in excess of 10% is undesired because doing so deteriorates the workability o~ mortar. ~
While the composition of the mortar to be used in accordance with the invention has been describedS it is necessary to adjust the viscosity of mortar depending upon the place of repair4 As has been mentioned above, the prior-art blas-t furnace repair ~mor-tar is in the form of a slurry containing a grea-t deal of ¦liquid and thus has presented such problems of :Elowing away up to la non-repair por-tion or of embroiling the furnace burden as it cures. In accordance with the invention, accordingly, it is ¦desirable to ad~ust the viscosity of mortar such tha-t the index ¦of viscosity based upon "JIS R2506, Method of Testing Refractory ¦Mortar Viscosity" is 180 to 250 par~ticularly for the repair of ¦bosh upper por-tion and local red hot portion. "JIS" herein ¦used is ab reviated irom ~!The Japanese Industrial Standards''.

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In -the mor-tar within this viscosity index range, the afore-mentioned pitch is 12 -to 18%, and ethylene oil is 10 to 15%, the rest being the base material.
l As mentioned earlier, however, mortar with an index of ~viscosity ranging from 180 to 250 can hardly be charged into the blast furnace inner wall by the prior-art mor~tar injec-tor. The ¦inventors have su.cceeded in the development o~ a device, which ¦can su.ccessfu.lly charge even the mortar having su.ch high viscosit~ .
A mortar charging device according to the invention will now be ¦described with reference to the accompanying drawings.
Referring to the accompanying drawings :
Fig. 1 is a sectional vlew showing a charging nozzle of a ~mortar charging device according to the invention iXl the opera-~ ting state;
: 15 Fig. 2 is a sectional view of guide rnember at the nozzle tip;
Fig. 3 is a side view a mortar charging device according to the invention;
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20 ¦ Fig. 4 is a view showing -the nozzle shown in Fig. 3;
E`ig. 5 is an eleva.-tional view of a rear side plate of a hou.sing which accommodates a force-out cylinder;
Fig. 6 i.s a side view, partly in sec~ion, showing another embod.imerlt of the mortar charging device according to -the ~5 in.vention;
: Fig. 7 is a side view, par-tly in section, showing a fu.rther embodiment of the mortar charging device according -to the invention; and Fig. 8 shows a mor-tar feed means employing a screw pump embodying the invention.
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Referring now to Fig. 1, a charging nozzle 20 of a mortar charging device according to the inven-tion is shown in its state inserted. through a mortar inser-tion hole formed in a blast ~ furnace wall 11. The furnace wall 11 consis-ts of a furnace skin 1 13 lined with a refractory material 12, for instance Chamotte ~bricksO~ When damage is caused to -the refractory material layer 12 as is shown in the Figure, the relevant portion of the furnace ¦skin becomes red hot. The nozzle 20 is mounted on the furnace Iwall with its flange 22 engaged with a mounting flange (15) of ~ the furnace skin 13 and secu.red thereto by bolts 23. The nozzle 20 has a guide member 26 secured to its end on the charging side ¦by support rods 24. The suppor-t rods 24 and guide member 26 may be secured by welding, and the support rods may be -two -to five in number.
¦ The back side cor~igu.ration of the gu.ide member 26 consti-¦ tu.-tes a featu.re of the invention. As is shown in section in Fig. 1, the guide member 26 has a central projection 28 pro-¦ jecting from its back side. Mortar is fed out under high pressu.r ¦ in the direction of the arrow in the Figu.re -throu.gh -the nozzle 20 by a suitable means. As mortar in a massy form strikes the Iprojection 28, i-t is su.bdivided and smoothly oharged along the ¦ arrows to the damaged portion of the f`urnace wall. Experimen-ts by the inventors have proved that if the center of the back side of the gu.ide member 26 has a.concave form, the mortar of high viscosi-ty is not subdivided but remain in the massy form to resu.lt in high pressu.re loss at the tip of ~he nozzle 20, giving rise to cloggm g of nozzle or cau.sing mortar to flow ou.t . in certain directions so that smooth charging cannot be obtained~
; Fu.rther9 when the g~.ide member 26 is not u.sed, of cou.rse mortar 3o of hlgh viscosity ialls in tbe furnace so that repair by . _ 9_ .' charging mortar cannot be ob-tained. The guide member 26 pre-ferably has a sectional profile as shown in Fig. 2, having a cen-tral projection Z8 projecting from the back side, with a concave line defined from the projection 28 toward the edge ¦ portion 29. In the guide member of Fig~ 1, the edge portion 29 projects with respect to the projection 28. In -this case, mortar is charged over a narrow range surrounding the charging hole 14. In other words9 the shape of the guide member of Fig.
1 is suited for the nozzle used for repair of a local red ho-t portion covering a small region. On the other hand, in a guide ¦ member shown in Fig. 2 the central projection 28 projects wi-th respect to the edge portion 29. In this case, mor-tar supplied in the massy form i5 subdivided by the projection 28 and is charged into a damaged region of a relatively large area. It is desirable -to selectively use guide members of differen-t back side configurations depending upon the size of the damaged ¦ portions of -the furnace inner wall. Further, when mortar of high viscosity is supplied under high pressure into a nozzle, ~ it is likely to block the nozzle wi-th a very large resistance 1 20 produced as it is rendered into a massy form between the nozzle end and guide mem~er. In order to prevent -this, the nozzle 20 ¦ may be provided in i-ts sultable portion wi.th a reduced diameter portion 30, which acts to divide massy mortar proceeding toward ¦ the nozzle tip~
Fig. 3 is an overall view o~ an embodiment of the mortar ¦charging means according to the invention. In the Figure, like ¦parts as in the preceding Figures are designated by like refer-¦ence numerals, and only different parts will be described~ In I the mortar charging means 8hown Fig. 3, the charging nozzle 20 ; 30 ~is connected to and communicated with a forcing cylinder 32, and .

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~a plunger 47 of the same diame~ter as the inner diameter of the forcing cylinder 32 is advanced into and retreated from the ~cylinder 32 by a hydraulic mechanism 48. Mortar pressure ~ charged into the forcing cylinder 32 is extruded into the furnace ~as the plunger 47 executes a stroke~ The forcing cylinder 32, ¦into which the mortar is charged9 is a cassette -type so that it can be readily replaced for charging mortar as speedily as possible. As shown in Fig. 4, the nozzle portion is connected -to a disc 22 having a hole 18 of the same diameter as the nozzle end ¦ outer form, for instance, by welding in its state ~itted in the hole 18. The disc 22 is secured to the mounting flange 15 the fu.rnace skin 13, for instance by bolts 21 together with a mounting disc 17 of a housing 38. The housing 38 includes a l front disc 40A, a rear disc 40B, a bot-tom member 42 and a side rod 44, these parts being integrally connected to one another.
I ¦ The mounting disc 17 is secured by bolts 25 to the front side I oE the front disc 40A. The disc 17 and front disc 40A of course ¦ have respective holes oE substantially the same diameter as -the nozzle inner diameter for communication with each other. The ¦ ~orcing cylinder 32 has substan~tially a cylindrical form wi.th flanges 34A and 34B provided on the ou-ter periphery~ and i-t is ¦ secured to the~bottom member 42 in a state fitted in grooves of the bottom member 42. It is desirable to couple the forcing ¦cylinder 32 and :Eron-t disc 40A liqu.id tight by a su.itable means.
¦It is convenient -to provide a grip 36 on the forcing cylinder for the repairing operation at a high site of the furnace wall.
¦Behind the forcing cylinder 32 a plunger 47 driven by.a hydraulic ¦mechanism 48 ~s provlded. As shown in Fig~ 5, the plunger 47 is ¦secu.red to the top of a hydraulic rod 49 penetrating a hole 46 oE the rear disc 40B. Its stroke is from the neighborhood of I : ., I : . , . . - - .

~the front end of the forcing cylinder to the position of its detachment at the rear end of -the forcing cylinder. The mortar ~is charged in a state where the plunger 47 iS detached from the ~forcing cylinder 32, and then the hydraulic rod 49 is advanced ~to charge mortar within the forcing cylinder 32 through the char-ging nozzle 20 into the furnace wall. For forcing ou.t mor-tar, the plunger ~7 preferably has a concave front su.rface as shown ¦by dashed line.
: Fig. 6 shows a different embodiment of the mor-tar charging ¦means according to the invention, which will now be described.
In this embodiment, a transducer 50 is pro~ided between the ~ charging nozzle 20 and forcing cylinder 32. As is shown in the : ¦Figu.re, the charging nozzle 20 is integral with a mounting disc 22, and the transducer 50 is integral with mounting disc flanges 1552A and 52B. Fu.rther, -the forcing cylinder 32 is integral with : ~the hou~sing 38. Thu.s, the nozzle 20, transducer 50 and forcing ¦cylinder 32 are independently portable at the time of mounting ; and remo~al, which is convenient for the operation at a high ¦si.~e of the blast ~urnace wall. In a repair portion of the blast furnace wall, a charging hole 14 is .~ormed, a moun-ting ring 19 ¦is welded to -the furnace skin 13, and a flange 15 is secu.red to the ring 19. When setting the device according to the invention, the disc 22 and the disc 52A o~ the transdu.cer are set in their registered positions with the charging nozzle 20 in a state penetrating -the furnace wall, and then they are secured to the : flange 15 by bolts 23. :Then, the front disc 40A of the housing 38 is registered with the disc flange 52B of the transdu.cer 50 : and then secu:red:thereto by means of bolts 25~ Packings 27A, 27B and 27C may be p:ro~ided respectively be-tween the flange 15 :~ and dlso 22, between the disc 22 and disc 52A and between the disc 52B and fron-t ~isc 40A for ensuring reliable tightening.
Al-though -the transducer 50 in the illustrated example has a uniform diameter, it is possible -to use a throttled form to ~provide for smooth charging of mortar. It will be readily ~ understood ~rom the environment of the repair operation that the transducer 50 according to the invention has an end o~ facilita-ting the setting o~ the device in addition to the end of providinl r for smooth charging of mortar.
lFig. 7 shows a still ~u.rther embodiment of the mortar charging device according to the invention. In -this embodiment, the forcing cylinder 32 is closed at its rear end and con-tains ¦ the plunger 47. Fu.rther, a mortar supply hopper 54 is provided on and in communication with the upper portion of the forcing ¦ cylinder 32, and a plunger 56 of a hydraulic drive means 58 is disposed within the mortar supply hopper 54. Thus, continuou.s ¦ charging of mortar can be obtained by preliminarily charging a : great qu.antity o~ mortar into the su.pply hopper 54. While the hydraulic drive mechanisms 48 and 58 are operated in an inter-¦ locked relation to each other, they may also be opera-ted ¦ mànually as well.
¦ Fig. 8 shows a menas for ~orcing out mortar under high ¦pressure in a further embodiment of the lnvention. A screw pump 61 is provided on a movable s-tand 60~ and a screw 62 within the pump is driven by a motor 64 -through a shaft 660 A mortar supply hopper 68 is provided on and in communication wi-th -the upper portion of the pump 61. Two rollers 70 and 70' are arranged parallel within the hopper 68 and are adapted to be rotated in :~ opposite directions to each other to thereby ~orce ou.t mortar within the hopper 68 into the pump. In the illustrated example, 3o the rollers 70 and 70' are driven by the same motor 64 via a -~l ~gear 72 meshing with a shaf-t 66. .A sha~t 74 o~ the rollers 70 ~and 70' is journalled i.n a bearing 74i and is driven by a gear ~72 a-t a constant rotational ra-tio. In this way, mortar is ~supplied under high pressure by the screw pump 61 and is charged into the ~urnace wall through the charging nozzle 32~ which is ~connected -to the open end 76 of the pump. The open end 76 of the pump may be connected to the guide member 26 by the support ¦rods 24~ In this case, the tip portion of the screw pump is inserted through the furnace wall.
10 ¦ An experiment example u.sing variou.s samples of mortar according to the invention will now be described.
Experiment Exam~le ¦ Mortar materials of compositions as listed in Table 1 were charged in-to iurnace skin at 300C. The adherence and resistance ¦ of -these materlals1 which were measu.red a~ter curing, are shown in Table 2.
¦ Table 1 Composition of sample re~ractory materials l (in weight %) Prior-ar-t Sample A Sample B Sample C Sample material ¦Refractory powder67 74 69 71 66 Coal pi-tch -- 6 6 6 6 ¦Petroleum pi-tch -~ 8 8 8 8 Ethylene bottom oil ~- 12 12 12 12 . ¦Steel fiber -- ~- 5 - 5 Phenol resin -- -- - 3 3 ¦Hydrau.lic hardener 10 -~
: Water Z3 ~~
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Properties at 300C (Kg/cm ) Adhesion Strength 0 12 9 17 15 Crushing Strength 26 31 39 45 52 It will be seen that the samples A to D of the refrac-tory material according to the invention are superior in adhesion and crushing strength to the prior-art refractory material.
While the invention has been described in conjunction with some preferred embodiments, but the embodiments are by no means limitative, and the invention is oE course defined by the accompanying claims.

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Claims (7)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A mortar to be used for repairing damaged portions of blast furnace inner walls, said mortar containing 5 to 30%
of pitch with a softening point of 70 to 250°C incorporated as binder, and 8 to 50% of ethylene bottom oil incorporated as fluidity imparting agent, the rest being a powdery re-fractory base material, and said ethylene bottom oil being the residue obtained when refining ethylene from naphtha.

2. The mortar according to claim 1, which contains 12 to 18% of pitch with a softening point of 70 to 250°C and 10 to 15% of ethylene bottom oil, the rest being the powdery refractory base material.

3. The mortar according to claim 1, wherein said powdery refractory base material is at least one member of a group consisting of mullite, sillimanite, kaolin, corundum, periclase and chromite.

4. The mortar according to claim 1, wherein said pitch is a member of a group consisting of petroleum pitch, coal pitch and mixtures of these pitches.

5. The mortar according to claim 1, which further contains 3% or less of heavy oil.

6. The mortar according to claim 1, which further contains 1 to 7% of a phenol resin.

7. The mortar according to claim 1, which further contains 10% or less of a metallic or carbonaceous fiber.