To provide a high-zirconia electrocast refractory in which occurrence of cracks in manufacture and occurrence of cracks in use as a furnace material is further reduced while maintaining extremely high corrosion resistance to molten glass. The high-zirconia electrocast refractory contains 96.7 to 98.5 mass % of ZrO.sub.2, 0.8 to 2.7 mass % of SiO.sub.2, 0 to 0.2 mass % of Na.sub.2O, 0.21 to 1 mass % of K.sub.2O, 0.1 to 0.4 mass % of Al.sub.2O.sub.3, and does not substantially contain B.sub.2O.sub.3, in terms of oxide, as a chemical composition, wherein contents of the Na.sub.2O and the K.sub.2O satisfy a relation of following Formula (1)

0.15 mass %C.sub.K2O/2+C.sub.Na2O0.6 mass %(1)

where C.sub.K2O is the content of K.sub.2O and C.sub.Na2O is the content of Na.sub.2O, and each of the contents is expressed by mass % in the refractory.

The invention concerns a batch for the production of a refractory magnesia-carbon product or a refractory alumina-magnesia-carbon product, a process for the production of a refractory magnesia-carbon product or a refractory alumina-magnesia-carbon product, a refractory magnesia-carbon product or a refractory alumina-magnesia-carbon product as well as the use of a magnesia-carbon product or a refractory alumina-magnesia-carbon product.

The invention concerns a batch for the production of a refractory magnesia-carbon product or a refractory alumina-magnesia-carbon product, a process for the production of a refractory magnesia-carbon product or a refractory alumina-magnesia-carbon product, a refractory magnesia-carbon product or a refractory alumina-magnesia-carbon product as well as the use of a magnesia-carbon product or a refractory alumina-magnesia-carbon product.

The invention relates to a composition for preparing a green body for the manufacture of a refractory carbon-bonded product, a method for preparing such a green body and a green body prepared by such a method.

The invention relates to a composition for preparing a green body for the manufacture of a refractory carbon-bonded product, a method for preparing such a green body and a green body prepared by such a method.

The invention relates to a melted and cast refractory product having a chemical composition such that, in mass percentages on the basis of the oxides: AI.sub.2O.sub.3: complement up to 100%; MgO: 26% to 50%; ZrO.sub.2: 0.5% to 10.0%; B.sub.2O.sub.3: <1.5%; SiO.sub.2: 0.5%; Na.sub.2O+K.sub.2O: 0.3%; CaO: 1.0%; Fe.sub.2O.sub.3+TiO.sub.2: <0.55%; other oxide species: <1.0%. In said product, the elementary mass ratio R of the zirconium content to the total boron, fluorine and silicon content is between 2 and 80.

The invention relates to a melted and cast refractory product having a chemical composition such that, in mass percentages on the basis of the oxides: AI.sub.2O.sub.3: complement up to 100%; MgO: 26% to 50%; ZrO.sub.2: 0.5% to 10.0%; B.sub.2O.sub.3: <1.5%; SiO.sub.2: 0.5%; Na.sub.2O+K.sub.2O: 0.3%; CaO: 1.0%; Fe.sub.2O.sub.3+TiO.sub.2: <0.55%; other oxide species: <1.0%. In said product, the elementary mass ratio R of the zirconium content to the total boron, fluorine and silicon content is between 2 and 80.