Abstract: A water-permeable ceramic material is made of a porcelain particulate material as the principle component, one or more primary binders selected from starch adhesives, organic binders, clay and water glass, and one or more secondary binders selected from frit, glaze and glass powder. The principal component is selected from one or more porcelain materials including a fired mixture of pottery stone, kaolin and feldspar; porcelain wastes, and other porcelain materials such as road-surfacing porcelain color aggregates, and is classified to have a particles are of relatively high bulk density and very low porosity. The mix is shaped by a pressing machine to a tabular or tubular form suited to the specific use of the final product. The pressure of the pressing machine is adjusted to an amount of 30-200 kg/cm.sup.2. After shaping, the resultant compact is sintered at a temperature up to the melting point of the porcelain particles to produce the ceramic material.

Abstract: A novel basic refractory composition is disclosed. This composition has high resistance to calcium silicates such as cement clinkers and slag formed in steelmaking operations. It also has superior resistance to thermal shock and stresses such as load in high temperature. A refractory brick produced from this composition can be used in the firing zone of a rotary kiln and successfully withstands cement firing operations for a significantly longer period than conventional refractory bricks.The basic refractory composition consists of a synthetic calcium zirconate based clinker in combination with raw materials for magnesia; the molar ratio of CaO to ZrO.sub.2 in said clinker is in the range of 0.5-1.1, at least part of said clinker being in the form of particles having a size not smaller than 0.5 mm, ZrO.sub.2 being present in an amount of 4-49 wt % of said composition, the sum of CaO and MgO being 50-95 wt %, and the sum of ZrO.sub.2, CaO and MgO being at least 80 wt %.

Abstract: A basic brick composition containing spinel clinker and magnesia clinker wherein pulverized iron oxide by additional weight mixing ratio is mixed or special magnesia clinker is substituted for magnesia clinker instead of addition of iron oxide.