Abstract: A permeable nozzle is made from MgO and MgO—Al2O3 spinel and has a nonservice backpressure of about 0.5-50 psi at gas flowrates of about 5-20 liters/minute. In one embodiment, the permeable nozzle comprises about 50%-80% of about a 20-48×100 mesh MgO, about 5%-20% of about a 325 mesh MgO and about 5%-40% of about a 48×200 mesh MgO—Al2O3 spinel. In another embodiment, the permeable nozzle comprises about 10%-20% of about a 20-48×100 mesh MgO, about 0%-10% of about a 325 mesh MgO, about 30%-60% of about a 28×48 mesh MgO—Al2O3 spinel, about 10%-40% of about a 48×200 mesh MgO—Al2O3 spinel, and about 10%-20% of about a 325 mesh MgO—Al2O3 spinel.

Abstract: A method of forming high density silica products, and the products formed therefrom, comprising the steps of:a) preparing a fused silica slip having a moisture content less than 25% by weight and fine silica particles of which about 90% are a size less than 55 microns;b) mixing the fused silica slip with coarse silica particles having a gram size greater than Tyler Mesh -4 to form a mixture having between 20-70% coarse particles;c) inserting the mixture into a mold of the product to be formed;d) vibrating the mold for a predetermined period of time sufficient to settle the coarse silica particles in the mold and to facilitate release of air bubbles from the mixture and hardening the mixture by drying to form a molded piece.

Abstract: There is provided a metallurgical well powder having reduced tendencies to hinder the flow of molten metal, by packing and jamming the opening, in a steel ladle for example, through which said molten metal will be teemed upon tapping said ladle.