Insulating material for covering cast steel

摘要

An insulating material contains finely powdered acidic and basic materials mixed in a matrix of a gel-forming material to form granules. Also claimed is the production of the material which comprises homogeneously mixing 100 parts of the insulating powders with 1-10 parts of the gel-forming material and 20-100 parts water or solvent miscible with water, forming into granules and drying. The gel-forming material is an animal protein such as collagen or gelatin, of plant polysaccharide such as cellulose (derivative), agar, ground guar, gum arabica, ground locust bean gum, or animal polysaccharide such as chitin. The gel-forming material has a water-binding ability of 30-50 times its own weight. The basic material is sintered magnesite, caustic calcined magnesite, chromite, fluorspar or calcined lime. The acidic material is fly ash, amorphous silicic acid or rice shell ash. Granule formation is carried out in a suitable mixer or granulator, and drying is carried out in a fluidised bed or belt dryer with heated air. The amount of gel-forming material is measured so that the bulk density of the granules obtained is 0.2-0.8 kg/l. The bulk density is reduced by adding 10-30 pts. wt. sodium bicarbonate.