| 摘要 |
1439253 Refractory compositions VEITSCHER MAGNESITWERKE - AKTIENGES 26 June 1973 [17 July 1972] 30286/73 Heading C1J A refractory material consists substantially of a burnt pre-reacted magnesia-chromite sinter grain and 1-5 wt. per cent of a water soluble phosphate as chemical binder; the sintered grain has a Cr 2 O 3 content of 10-30 wt. per cent, a MgO content of above 42%, SiO 2 and CaO contents of at the most 3% each, and a lime-silica weight ratio above 1, with the chromite constituents being present practically wholly in the form of spinel aggregations and residual constituents of the original chromite grains being present only to the extent of at the most 10 volume per cent of the sintered grain. The phosphate can be potassium tripolyphosphate or tetrapotassium pyrophosphate and can contain sodium dihydrogen phosphate of disodium hydrogen phosphate; boric acid or a water soluble borate can be included as binder. The refractory material can be used, together with 2-4 wt. per cent water as ramming material or together with up to 10 wt. per cent water as casting material, for lining, or making brick for lining, vacuum degasification vessels for steel production of for lining the roof of an electric arc steel melting furnace. In an example the use of potassium tripolyphosphate as binder is compared with the use of sodium bichromate, magnesium sulphate, waterglass, aluminous cement and sodium bisulphate. |
