In the field of refining metal melts or slags there is disclosed in particular a reactive material based on calcium aluminate and carbon, its process of preparation and various methods for refining metal melts using the same.

A method of producing a ceramic core for investment casting is provided. The method includes injecting a slurry into a disposable die. The slurry includes ceramic particles, a binder, and carbon fibers. The method also includes a first heating to eliminate the disposable die, leaving a cured ceramic core comprising the ceramic particles, binder, and carbon fibers.

Provided is a method for suppressing rear face oxidation and a lining structure, with which high airtightness and a great effect of suppressing rear face oxidation are obtained. The method for suppressing rear face oxidation of a carbon-containing refractory includes forming an adherent layer on a rear face of a carbon-containing refractory by applying an alkali metal silicate aqueous solution to the rear face and solidifying the alkali metal silicate aqueous solution. The alkali metal silicate aqueous solution contains an alkali metal oxide R.sub.2O (R is an alkali metal element) and SiO.sub.2 and has a molar ratio of SiO.sub.2 to the alkali metal oxide of 2.3 or more. The carbon-containing refractory is used at a high temperature of 400 C. or more and contains 1 mass % or more of carbon or a carbon compound.

Provided is a method for suppressing rear face oxidation and a lining structure, with which high airtightness and a great effect of suppressing rear face oxidation are obtained. The method for suppressing rear face oxidation of a carbon-containing refractory includes forming an adherent layer on a rear face of a carbon-containing refractory by applying an alkali metal silicate aqueous solution to the rear face and solidifying the alkali metal silicate aqueous solution. The alkali metal silicate aqueous solution contains an alkali metal oxide R.sub.2O (R is an alkali metal element) and SiO.sub.2 and has a molar ratio of SiO.sub.2 to the alkali metal oxide of 2.3 or more. The carbon-containing refractory is used at a high temperature of 400 C. or more and contains 1 mass % or more of carbon or a carbon compound.

The present invention relates to a dry refractory particulate composition comprising a zeolithic microstructure, to a green body and to a refractory lining formed therefrom, and to uses thereof.

The present invention relates to a compound for making high-temperature-resistant or refractory molded bodies, made up of a mixture of: a refractory or high-temperature-resistant inorganic powder, granules and/or granulate, including a free-flowing compound or a powder made of carbon or also without carbon, a binder,
the binder being made of a combination of tannin, lactose, fine-grained silica and aluminum powder, as well as the binder itself, and molded bodies produced from the compound including the binder, and a method of making same.

A batch made of refractory mineral materials for lining of assemblies used for nonferrous metal melts, contains over 90% by weight of a mixture of the following constituents:from 3 to 74% by weight of at least one coarse-grain raw olivine material with at least 70% by weight forsterite content and having grain sizes of 50% by weight over 0.1 mmfrom 25 to 49% by weight of at least one ground magnesia with grain sizes of 50% by weight?1 mmfrom 0.9 to 14% by weight of at least one ground silicon carbide (SiC) with grain sizes of 50% by weight?1 mmfrom 0.1 to 10% by weight of at least one fine-particle dry pulverulent silica with particle sizes?500 ?mfrom 0 to 4% by weight of at least one antioxidant known per se for refractory productsfrom 0 to 4% by weight of at least one additional granulated refractory raw material known per se, more particularly having grain sizes of 50% by weight, in particular of 80% by weight, preferably of 100% by weight over 0.1 mmfrom 0 to 2% by weight of at least one additive known per se for the production of refractory products from batchesfrom 0 to 4% by weight of at least one additional substance known per se made of ground refractory materials and/or in the form of what is known as medium-grain-size material and/or of what is known as coarse-grain-size materialfrom 0 to 10% by weight of at least one binder known per se for refractory materials, e.g. in dry form or in ancillary packaging in liquid form.

A method of making a refractory article is provided. The method includes: a) mixing a binder system, a refractory charge, and a second colloidal binder to form an aqueous slurry; b) casting the aqueous slurry into a mold; c) subjecting the mold containing the aqueous slurry to a temperature that is lower than a slurry casting temperature for a time sufficient to form a green strength article; and d) firing the green strength article at a temperature of at least 450? C. for a time sufficient to achieve thermal homogeneity, thereby forming a refractory article. Refractory articles made in accordance with the method have a unique combination of pore structure and mechanical properties.

An alkaline-activated binder system for fire concretes includes at least one mineral binder and a mineral activator which, in a mixture with water, form a curing geopolymer, where a combination of at least two magnesium components (Mg components) which give an alkaline reaction with water and react with the binder at different times to form a geopolymer is present as activator, where the magnesium components have a different reactivity in respect of atmospheric moisture and/or in respect of the binder. A dry fire concrete mix contains the binder system and the mix may be used in, for example, facilities in the steel industry.

The invention relates to a refractory product comprising zirconium dioxide, a use of zirconium dioxide, a zirconium dioxide, a method for manufacturing a refractory product and a refractory product manufactured by means of said method. The zirconium dioxide is in cubic form and is metastable at room temperature. The zirconium dioxide has a content of calcium, magnesium and yttrium of less than 1% by weight.