Abstract: A low cement castable refractory comprising 85 to 96% by weight of a calcined ultrafine bauxite aggregate characterized by a particle size of less than 10 um, 2 to 10% by weight of a suitable cement material, 0 to 8% of weight of a thixotropic agent and 0 to 2% by weight of suitable deflocculants and plasticizers, the cement material comprising calcium aluminate cement having an alumina content of 40 to 85% and the thixotropic agents being selected from those containing microfine silica, and/or reactive alumina, the inorganic deflocculants and plasticizers being selected from alkali phosphates, lignosulphonates or naphthalene sulphonates. A method of making a low cement castable refractory and installing a low cement castable refractory are also described.

Abstract: A filter medium suitable for hot liquid and gaseous materials, more particularly molten metals, for example aluminium and its alloys, is characterized by the use of sintered ultrafine bauxite granules. Filter media according to the invention exhibit superior thermal shock resistance, may be used repeatedly and are much cheaper than filter media of the prior art.