Process for preparing carbon-containing refractory ceramic masse

Details Process for preparing carbon-containing refractory ceramic masse Process for preparing carbon-containing refractory ceramic masse

1994-09-08

1997-05-13

Fiorilla, Cristopher A.

Plastic and nonmetallic article shaping or treating: processes

Carbonizing to form article

264 296, C01B 3100

Patent

active

056289391

DESCRIPTION:

BRIEF SUMMARY
SPECIFICATION

The present invention pertains to a process for preparing a carbon-containing refractory ceramic molding (workpiece), as well as a carbon-containing refractory ceramic mass.
The binding of refractory materials and moldings with coal products, such as tar or pitch, has been known for a long time. A binding pitch matrix is formed during the heat treatment of the products. The secondary carbon thus formed is responsible for the strength of the product at the application temperature, but at the same time also for a favorable resistance to corrosive (metallurgical) slags, as well as for an infiltration-inhibiting action. However, the formation of the binding pitch matrix depends on the presence of aromatic compounds in the starting binder. In the case of coal tar, these are condensed polycyclic aromatic compounds, which are considered to be carcinogenic.
Therefore, there is now increasingly a change from pitch or tar to the use of synthetic resins as binders. The problem of the polycyclic aromatics is eliminated as a result. However, when phenolic resins are used (DE 32 12 671 A1), a health hazard is attributed to the monomer phenol contained in them, as well as to the decomposition products [formed] after a heat treatment. In addition, DE 37 21 642 C2 describes alicyclic hydrocarbon products of the terpene or natural resin type, and DE 39 17 965 C1 discloses various resins, especially of the epoxy type, as binders for refractory masses. Hydrocarbon and terpene resins are obtained from residues processing or from coal tar. All these binders share the common feature of having a considerable carbon residue after pyrolysis. A strength-increasing carbon skeleton is formed during coking in this case as well, but the carbon residue formed from synthetic resins is less resistant to oxidation for structural reasons than the secondary carbon formed from pitch or tar.
DE 32 12 671 C2 discloses carbon-containing refractory bricks, which contain an organic polymer, namely, a resorcinol polymer, as the binder, besides the basic refractory matrix material. Residues which are hazardous to health are also formed during the heat treatment of such bricks, but they are accepted as a compromise in exchange for the formation of a secondary carbon skeleton.
U.S. Pat. No. 4,061,501 A discloses a process for preparing a refractory lining material, in which refractory granules of < 6 mm from the group comprising magnesite, dolomite, etc., 2-15 wt. % of a binder from the group comprising bonding clay, phosphoric acid, etc., and 0.4 to 4.0 wt. % of colloidal silicic acid are mixed with a carbon-containing material, such as coke or graphite (screened to < 1 mm), and processed.
Thus, the basic task of the present invention is to provide a process for preparing a carbon-containing refractory ceramic mass and a molding, which makes possible pollutant-free preparation and use, without having to accept an appreciable loss of strength and without deterioration of the resistance to infiltration or of the resistance to corrosive slags.
The present invention is based on the discovery that this goal can also be accomplished when a non-coking polymer is used as the binder. This must be surprising, because it was assumed in the state of the art that a sufficient green strength as well as a sufficient strength after heat treatment can be achieved only if a corresponding carbon skeleton is formed by the binder.
However, carbon binding using the binder is deliberately dispensed with by the use of non-aromatic organic polymer compounds as the binder.
It was determined that a sufficient green strength can also be achieved by means of a binder whose organic components are removed without residue under the effect of temperature, and thus they are no longer available for the formation of a secondary carbon skeleton, which is considered to be indispensable according to the state of the art. At low temperatures (up to ca. 300.degree. C.), the polymer compound acts as an "adhesive," and the other components of the mixture, namely, the refra

REFERENCES:
patent: 4061501 (1977-12-01), Ivarsson et al.
patent: 4558019 (1985-12-01), Kotliar et al.
patent: 4959255 (1990-09-01), Suzuki

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