A silicon carbide porous body includes: (A) silicon carbide particles as an aggregate; and (B) at least one selected from the group consisting of metallic silicon, alumina, silica, mullite and cordierite. The silicon carbide porous body has amorphous and/or crystalline SiO.sub.2 or SiO on a surface(s) of the component (A) and/or the component (B). The silicon carbide porous body contains 6% by mass or less of -cristobalite in the amorphous and/or crystalline SiO.sub.2 or SiO.

Plant for the recovery of spent refractory material in steel plants, comprising at least one receiving area (1) for said refractory material, at least one material sieving area (2), at least one magnetic separation area (3) and at least one sorting area (4).

Said receiving area (1) communicates with a first sieving area (2) comprising first sieving means intended to divide said refractory material in at least two fractions, of which a coarse fraction and a fine fraction, on the basis of the size of said material.

There is further provided a second sieving area (21) comprising second sieving means intended to divide said fine fraction into at least two further sub-fractions (A, B, C) on the basis of size.

Plant for the recovery of spent refractory material in steel plants, comprising at least one receiving area (1) for said refractory material, at least one material sieving area (2), at least one magnetic separation area (3) and at least one sorting area (4).

Said receiving area (1) communicates with a first sieving area (2) comprising first sieving means intended to divide said refractory material in at least two fractions, of which a coarse fraction and a fine fraction, on the basis of the size of said material.

There is further provided a second sieving area (21) comprising second sieving means intended to divide said fine fraction into at least two further sub-fractions (A, B, C) on the basis of size.

The invention relates to granules composed of agglomerated reactive bulk material and a binder matrix, the binder matrix comprising as binder an organic or inorganic salt.

The invention relates to granules composed of agglomerated reactive bulk material and a binder matrix, the binder matrix comprising as binder an organic or inorganic salt.

A precursor mixture for producing a porous body, wherein the precursor mixture comprises: (i) milled alpha alumina powder having a particle size of 0.1 to 6 microns, (ii) boehmite powder that functions as a binder of the alpha alumina powders, and (iii) burnout materials having a particle sizes of 1-10 microns. In some embodiments, an unmilled alpha alumina powder having a particle size of 10 to 100 microns is also included in said precursor mixture. Also described herein is a method for producing a porous body in which the above-described precursor mixture is formed to a given shape, and subjected to a heat treatment step in which the formed shape is sintered to produce the porous body.

A nozzle sand and method of use and operation, utilizes as a constituent component a granulated material that will break down to lose structural integrity and strength when subjected to temperatures and weight of molten ferrous materials, to compact to form at least a partial barrier to penetration of the molten ferrous material while remaining at least substantially in a granulated state. When the nozzle is opened, the loose nozzle sand will freely flow from the nozzle and the barrier will break under the weight of the ferrous material, such that the ferrous material will flow from the vessel through the nozzle. As a representative formulation, the nozzle sand can include between about 50 percent and about 60 percent by weight raw dolomitic lime; between about 20 percent and about 30 percent by weight forsterite; and between about 15 percent and about 20 percent by weight tabular alumina.

A nozzle sand and method of use and operation, utilizes as a constituent component a granulated material that will break down to lose structural integrity and strength when subjected to temperatures and weight of molten ferrous materials, to compact to form at least a partial barrier to penetration of the molten ferrous material while remaining at least substantially in a granulated state. When the nozzle is opened, the loose nozzle sand will freely flow from the nozzle and the barrier will break under the weight of the ferrous material, such that the ferrous material will flow from the vessel through the nozzle. As a representative formulation, the nozzle sand can include between about 50 percent and about 60 percent by weight raw dolomitic lime; between about 20 percent and about 30 percent by weight forsterite; and between about 15 percent and about 20 percent by weight tabular alumina.

A method for producing granulates, particularly for use as thermal insulation for a metal melt may include mixing a powdery mineral with a binder, and the mixture may be granulated in order to produce a semi-finished product. The granulate mixture or the semi-finished product may be heated rapidly to a temperature above the melting temperature or decomposition temperature of the binder, which may be in the form of a salt, so that the binder decomposes, whereby gas is released and the volume increases. The apparent density of the granulate mixture may decrease, and therefore the apparent density of the finished product may decrease with respect to the semi-finished product.

A method for producing granulates, particularly for use as thermal insulation for a metal melt may include mixing a powdery mineral with a binder, and the mixture may be granulated in order to produce a semi-finished product. The granulate mixture or the semi-finished product may be heated rapidly to a temperature above the melting temperature or decomposition temperature of the binder, which may be in the form of a salt, so that the binder decomposes, whereby gas is released and the volume increases. The apparent density of the granulate mixture may decrease, and therefore the apparent density of the finished product may decrease with respect to the semi-finished product.