GB2259509A - Fired fireproof ceramic body - Google Patents
Fired fireproof ceramic body Download PDFInfo
- Publication number
- GB2259509A GB2259509A GB9218948A GB9218948A GB2259509A GB 2259509 A GB2259509 A GB 2259509A GB 9218948 A GB9218948 A GB 9218948A GB 9218948 A GB9218948 A GB 9218948A GB 2259509 A GB2259509 A GB 2259509A
- Authority
- GB
- United Kingdom
- Prior art keywords
- firing
- body according
- fired
- carbon
- block
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000000919 ceramic Substances 0.000 title claims abstract description 25
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 32
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 23
- 238000010304 firing Methods 0.000 claims abstract description 13
- 239000000203 mixture Substances 0.000 claims abstract description 13
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 8
- 239000010439 graphite Substances 0.000 claims abstract description 8
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 7
- 150000004706 metal oxides Chemical class 0.000 claims abstract description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 4
- 238000002156 mixing Methods 0.000 claims abstract description 3
- 238000007493 shaping process Methods 0.000 claims abstract 2
- 239000002245 particle Substances 0.000 claims description 4
- 239000000571 coke Substances 0.000 claims description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 abstract 1
- 239000011230 binding agent Substances 0.000 abstract 1
- 229910052593 corundum Inorganic materials 0.000 abstract 1
- 229910001845 yogo sapphire Inorganic materials 0.000 abstract 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 46
- 235000012245 magnesium oxide Nutrition 0.000 description 24
- 239000000395 magnesium oxide Substances 0.000 description 24
- 238000000034 method Methods 0.000 description 6
- 230000005012 migration Effects 0.000 description 6
- 238000013508 migration Methods 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 238000009792 diffusion process Methods 0.000 description 5
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000001354 calcination Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229920001732 Lignosulfonate Polymers 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 229960000869 magnesium oxide Drugs 0.000 description 2
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910001425 magnesium ion Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000002006 petroleum coke Substances 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
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
- C04B35/66—Monolithic refractories or refractory mortars, including those whether or not containing clay
-
- 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
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/64—Burning or sintering processes
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Compositions Of Oxide Ceramics (AREA)
- Ceramic Products (AREA)
Abstract
A fired fireproof ceramic body is based on metal oxides, in particular CaO, MgO and/or Al2O3 It contains 1.0 to 12% residual carbon content and is made by mixing a carbonaceous component e.g. graphite into a block mixture of the oxide, binding agent and water, shaping the mixture and firing it under reducing conditions at 1400 DEG to 1700 DEG C.
Description
7 ' r. r. - ' Fired Fireproof Ceramic Body D e s c r i p t i o n The
invention relates to a fired fireproof ceramic body based on metal oxides, in particular based on CaO, MgO
and/or A1203. The prior art and the invention will be described in more detail in the following with reference to a magnesia block, but also apply analogously to products based on other metal oxides.
Magnesia blocks have been known for a long time. The firing of magnesia blocks having a ceramicbonding requires oxidising burning conditions.
In order to generate a ceramic bonding, "migration processes" must be initiated which lead to the occurrence of bridges between the magnesiumoxide particles to be bonded. In the case of the Mgo lattice, "migration processes" of this kind, which are termed diffusions, take place in technically acceptable periods from approximately 10OWC. Magnesia blocks have a relatively high porosity.
In order to obtain blocks with increased resistance to infiltration or resistance to aggressive (metallurgical) slags, carbonaceous mixtures are preferred. The bonding of fireproof materials or shaped parts for example with hard coal products such as tar or pitch has been known f or a long time. For the bonding the medium is held above its melting point to a certain viscosity, with the aid of a heating device, is mixed with the fireproof matrix material and is processed into a mass which is subsequently pressed, for example, into shaped bodies.
Although this process has fundamentally proved good, it does have the disadvantage that a costly hot-mixing process must be carried out. In this respect, pitch or tar vapours emerge to an intensified extent, which can lead not only to an unpleasant smell, but are also a danger to health.
Magnesia carbon blocks have also become a standard constituent of the range of fireproof products in recent years. Compared with the pitch-bonded properties named above, magnesia carbon blocks are distinguished by an increased content of residual carbon (mostly 10 to 20%), by the use of high-grade sintered magnesia and in.part molten magnesia as well as with higher residual carbon contents by the use of synthetic-resin bonds.
In each case the fireproof material is bonded by a carbon structure. At higher temperatures there is danger of a calcination of carbon, the bonding then being lost and the block disintegrating.
To improve the product qualities it would be desirable to obtain a carbonaceous, fireproof, shaped body with ceramic bonding. However, one has hitherto proceeded on the assumption that this is not possible because a calcination of the carbon has to be reckoned with, even with relatively low oxygen partial pressure in the furnace.
In contrast, the invention makes available a fired, fireproof ceramic body based on metal oxides with a residual carbon content of 1.0 to 12.0% by weight based on the total mass, wherein the carbon is present in such a manner that it is homogeneously distributed in the block structure, which itself has a ceramic bonding.
We have found that such a carbonaceous magnesia block can be attained if a finely graded, carbonaceous component is mixed homogeneously into the fireproof block mixture, the total mixture is subsequently shaped together and is subsequently fired, namely under reducing conditions at a temperature between 1400 and 170TC. The term "fireproof block mixture" in this respect comprises a block mixture based on the metal oxides named, including usual, in particular chemical, bonding means such as lignosulfonate, and water, that is to say a block mixture as is usually used also for carbon-free products.
This result must be surprising on the basis of hithertoexisting knowledge, namely for the following reasons.
The diffusion processes described above usually gccur during the firing of magnesia blbcks as follows:
By way of a solids migration over and along the grain boundaries. In this respect the magnesium ions migrate in the solid state, whereby a type of collective crystallization takes place, which cures lattice faults or dislocations. A dislocation is in this respect the contact region between two is differently orientated crystals. These crystals first of all form a bridge (ceramic bonding) and in the most favourable case can finally grow together into a single crystal.
Through migrations over the gas phase. However, this only takes place to a quantitatively relevant extent from about 170WC, whereby the oxygen partial pressure plays a decisive role, since with too little partial pressure a reduction of the MgO to Mg vapour takes place, which is discharged from the furnace with the gas atmosphere of the furnace.
Hence, according to hitherto-exi sting knowledge, reducing conditions break down the magnesia component at higher burning temperatures over the gas atmosphere and prevent a ceramic bonding.
Migrations during the melting phase. However, with the ceramic bonding of a technically manufactured magnesia block one stays with the firing temperature far below the melting temperature of the magnesia sinter and one uses the diffusion processes named above. Nevertheless, dif fusions in melting phases do occur to a certain extent, since each ceramic product has a certain proportion of impurities which form melts at the given technical firing temperature. By way of these melts a relatively large substance transport can take place, whereby here also with greatly reducing conditions a reduction of the magnesium oxide takes place and the oxygen is depleted or is used by other block components for oxidation.
These diffusion processes therefore theoretically oppose the attainment of a ceramic bonding in a magnesia carbon block.
Nevertheless, however, it has been found that the ceramic bonding is also possible with the use of, for example, graphite, if the shaped, carbonaceous ceramic body is treated under the conditions named. The substantial advantage of the carbonaceous shaped part in accordance with the invention lies in its ceramic bonding, so that even in case of calcination of carbon at high temperatures in use the stability of the block is ensured by way of the ceramic bonding.
In this respect, it is particularly advantageous to fire the body in a muffled way. The muffle should be formed according to an advantageous embodiment by means of a similarly carbonaceous bed, which screens the body to be fired against the furnace atmosphere. Such a bed can be a coke bed for example; however, other solid carbon carriers can also be used, for example from ground/broken electrode graphite.
In this respect the firing process can-be carried out in a conventional furnace unit, for example in a tunnel kiln.
The best results can be attained if the carbon particles (for example flake graphite) in the block structure have a maximum diameter smaller than lmm. In this respect, the carbonaceous component can replace the fine-grain portion of the fireproof magnesia matrix material at least in part.
In a conventionally manufactured magnesia carbon block generation of a ceramic bonding by means of f iring is not possible. This is because the development of a magnesia carbon block aims among other things for as low a porosity as possible, which is finally achieved through as complete a residual-area filling as possible in the micro structure with carbon carriers. In this way, on firing of the block practically no more migration processes between the individual MgO particles are possible. The consequence is that no ceramic bonding can be attained either.
By contrast, the block mixture is made up in accordance with the invention in such a way that MgO-MgO-contacts are attained in a controlled manner on f iring and the carbon carrier only lies additionally in the structure (as filling material as it were).
The invention is explained in more detail in the following with reference to two exemplary embodiments.
Example 1:
A conventional magnesia block mixture of magnesia sinter (including chemical bonding means, here lignosulfonate, and water) is mixed with 2% by weight f lake graphite.
Blocks were subsequently pressed f rom the mixture and fired for four hours at 15500C in a coke-bed muffle.
A perfect ceramic bonding with undisturbed graphite inclusions was achieved, as can be inferred from Figure 1.
The block has the following test data:
Density (g/CM3) Porosity ( by vol.) Resistance to cold compression (N/mmI) Residual carbon (% by mass) Example 2:
2.97 11.8 47.0 2.48 A block mixture according to Example 1 is mixed with 6% by weight flake graphite and subsequently pressed into blocks.
The blocks are subsequently fired in a tunnel kiln (14 hours transit time, 9 hours firing duration to approximately 1600OC) in a muff le of petroleum coke.
The blocks show a ceramic bonding and a structure analogous to Example 1.
The test data are as follows:
Density (g/cm') Porosity (% by vo.) Resistance to cold compression (N/MM2) Residual carbon (% by mass) 9 2.92 12.60 34.20 4.97
Claims (10)
1. Fired fireproof ceramic body based on metal oxides with a residual carbon content of 1.0 to 12.0% by weight based on the total mass, wherein the carbon is present homogeneously distributed as such in the block structure, which itself has a ceramic bonding.
2. Body according to claim 1, obtained by homogeneous mixing of a finely graded, carbonaceous component into the metal-oxide block mixture (including bonding means and water), common shaping and subsequent firing of the body shaped under reducing firing conditions at a temperature between 1400 and 1700T.
3. Body according to claim 1 or 2, obtained by firing the body inside a muffle.
4. Body according to claim 3, obtained by firing the body in a carbonaceous bed.
5. Body according to claim 4, obtained by f iring the body in a coke or graphite bed.
6. Body according to one of claims 1 to 5, obtained by firing in a tunnel-kiln.
7. Body according to one of claims 1 to 6, in which the carbon particles in the block structure have a diameter smaller than lmm.
8. Body according to claim 7 with a residual carbon content of 2.0 to 7. 0% by weight based on the total mass.
9. A f ired fireproof ceramic body substantially as herein described with reference to Example 1.
10. A fired fireproof ceramic body substantially as herein described with reference to Example 2.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19914130452 DE4130452A1 (en) | 1991-09-13 | 1991-09-13 | BURNED FIRE-RESISTANT CERAMIC KOERPER |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9218948D0 GB9218948D0 (en) | 1992-10-21 |
| GB2259509A true GB2259509A (en) | 1993-03-17 |
Family
ID=6440506
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9218948A Withdrawn GB2259509A (en) | 1991-09-13 | 1992-09-08 | Fired fireproof ceramic body |
Country Status (4)
| Country | Link |
|---|---|
| DE (1) | DE4130452A1 (en) |
| FR (1) | FR2682102A1 (en) |
| GB (1) | GB2259509A (en) |
| SE (1) | SE9202451L (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19938817C2 (en) * | 1999-08-19 | 2001-07-05 | Veitsch Radex Gmbh Wien | Refractory ceramic molded body |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3615775A (en) * | 1970-06-10 | 1971-10-26 | Dresser Ind | High alumina refractory composition |
| US3943216A (en) * | 1974-01-07 | 1976-03-09 | General Refractories Company | Production of periclase refractory utilizing alkyd resins |
| US4049461A (en) * | 1972-03-31 | 1977-09-20 | Osterreichisch-Amerkianische Magnesit Aktiengesellschaft | Unfired, refractory, basic bricks and compositions and their method of manufacture |
| GB2040911A (en) * | 1979-02-09 | 1980-09-03 | Kyushu Refractories | Carbon-containing refractory bricks |
| WO1984000158A1 (en) * | 1982-06-29 | 1984-01-19 | Nippon Kokan Kk | Magnesia-carbon-silicon carbide refractory |
| EP0150092A2 (en) * | 1984-01-17 | 1985-07-31 | Shinagawa Refractories Co., Ltd. | A carbon-containing refractory |
| EP0193751A2 (en) * | 1985-03-06 | 1986-09-10 | Didier-Werke Ag | Use of cement-free vibratable masses based on alumina and/or zirconia for producing wear-resisting parts |
| EP0242849A2 (en) * | 1986-04-21 | 1987-10-28 | Vesuvius Crucible Company | Carbon bonded refractory bodies |
| GB2202220A (en) * | 1987-03-11 | 1988-09-21 | Jet Refractories Limited | Refractory compositions for use in processing metals |
| WO1990000102A1 (en) * | 1988-07-01 | 1990-01-11 | Vesuvius France S.A. | Material for covering pouring devices |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1964433C3 (en) * | 1969-12-23 | 1983-12-15 | Stoecker & Kunz Gmbh, 4150 Krefeld | Use of carbon material to make stoppers and spouts |
| GB1344618A (en) * | 1970-02-27 | 1974-01-23 | Steetley Mfg Ltd | Refractory products |
| DE2810043A1 (en) * | 1978-03-08 | 1979-09-20 | Georg Mendheim Gmbh | Heat treating refractory bricks contg. tar - to remove volatile constituents in tar content by heating in oxygen free inert gas |
| IT1178519B (en) * | 1984-09-28 | 1987-09-09 | Alusuisse Italia Spa | PROCEDURE FOR THE PRODUCTION OF CARBON BODIES |
| DE3714398A1 (en) * | 1987-04-30 | 1988-11-10 | Emil Karl Dr Ing Koehler | Process for producing carbon-containing refractory products |
| DE3816571A1 (en) * | 1988-05-14 | 1989-11-23 | Dolomitwerke Gmbh | METHOD FOR PRODUCING FIREPROOF SHAPED BODIES |
| DE4040159A1 (en) * | 1989-12-18 | 1991-06-20 | Zschimmer & Schwarz Gmbh & Co | Carbon-forming additive for refractory prods. - comprising carbon source and dehydrating reactant, used in ferrous metallurgy |
| US5011802A (en) * | 1990-01-22 | 1991-04-30 | A.P. Green Industries, Inc. | Coking tar impregnated refractory products |
-
1991
- 1991-09-13 DE DE19914130452 patent/DE4130452A1/en not_active Withdrawn
-
1992
- 1992-08-26 SE SE9202451A patent/SE9202451L/en not_active Application Discontinuation
- 1992-09-08 GB GB9218948A patent/GB2259509A/en not_active Withdrawn
- 1992-09-11 FR FR9210835A patent/FR2682102A1/en active Pending
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3615775A (en) * | 1970-06-10 | 1971-10-26 | Dresser Ind | High alumina refractory composition |
| US4049461A (en) * | 1972-03-31 | 1977-09-20 | Osterreichisch-Amerkianische Magnesit Aktiengesellschaft | Unfired, refractory, basic bricks and compositions and their method of manufacture |
| US3943216A (en) * | 1974-01-07 | 1976-03-09 | General Refractories Company | Production of periclase refractory utilizing alkyd resins |
| GB2040911A (en) * | 1979-02-09 | 1980-09-03 | Kyushu Refractories | Carbon-containing refractory bricks |
| WO1984000158A1 (en) * | 1982-06-29 | 1984-01-19 | Nippon Kokan Kk | Magnesia-carbon-silicon carbide refractory |
| EP0150092A2 (en) * | 1984-01-17 | 1985-07-31 | Shinagawa Refractories Co., Ltd. | A carbon-containing refractory |
| EP0193751A2 (en) * | 1985-03-06 | 1986-09-10 | Didier-Werke Ag | Use of cement-free vibratable masses based on alumina and/or zirconia for producing wear-resisting parts |
| EP0242849A2 (en) * | 1986-04-21 | 1987-10-28 | Vesuvius Crucible Company | Carbon bonded refractory bodies |
| GB2202220A (en) * | 1987-03-11 | 1988-09-21 | Jet Refractories Limited | Refractory compositions for use in processing metals |
| WO1990000102A1 (en) * | 1988-07-01 | 1990-01-11 | Vesuvius France S.A. | Material for covering pouring devices |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2682102A1 (en) | 1993-04-09 |
| GB9218948D0 (en) | 1992-10-21 |
| SE9202451D0 (en) | 1992-08-26 |
| SE9202451L (en) | 1993-03-14 |
| DE4130452A1 (en) | 1993-03-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |