GB1095621A - Lining for the head of an ingot mould or for the head box of such a mould - Google Patents

Abstract

A multilayer slab, sleeve or the like, for lining the head of an ingot mould or a head box, comprises two layers of different composition and thickness. The thicker layer comprises fibrous cellulosic material, a basic refractory carbonate, e.g. dolomite or limestone, and a binder. The thinner layer, as a surface coating on the thicker layer, comprises a non-acidic, non-gas-generating refractory, e.g. calcined alumina or a silicate of high aluminium content, and a binder. This latter layer may also contain a fibrous material, in which case the two layers may have compositions which differ only in the identity of the refractory material. The slab, sleeve or the like may be made by forming the constituents for each layer into an aqueous slurry, dewatering one of the slurries on a mesh surface, applying the other slurry to the layer of solids on the mesh surface, dewatering the second slurry and drying. Alternatively, a slab, sleeve or the like is first formed from a slurry composition containing a basic refractory carbonate, and the composition containing the non-acidic, non-gas-generating refractory then applied to the slab as a surface dressing. In this case, the thick layer may be dried before application of the thin layer, or the two may be dried together after application of the latter. The fibrous cellulosic material may be paper pulp. Either or both of the layers may contain a proportion of fibrous refractory material, e.g. asbestos. In use, it is the thinner layer which faces towards the interior of the mould. In Example 1, a slab is made by the two-slurries method, and the binder in each layer comprises phenol-formaldehyde and ureaformaldehyde resins.ALSO:A multilayer slab, sleeve or the like, for lining the head of an ingot mould or a head box, comprises two layers of different composition and thickness. The thicker layer comprises fibrous cellulosic material, a basic refractory carbonate, e.g. dolomite or limestone, and a binder. The thinner layer, as a surface coating on the thicker layer, comprises a non-acidic, non-gas-generating refractory, e.g. calcined alumina or a silicate of high aluminium content, and a binder. This latter layer may also contain a fibrous material, in which case the two layers may have compositions which differ only in the identity of the refractory material. The slab, sleeve or the like may be made by forming the constituents the thicker layer into an aqueous slurry, dewatering on a mesh surface and applying the other layer to the slab as a surface dressing. In this case, the thick layer may be dried before application of the thin layer, or the two may be dried together after application of the latter. The fibrous cellulosic material may be paper pulp. Either or both of the layers may contain a proportion of fibrous refractory material e.g. asbestos. In use, it is the thinner layer which faces towards the interior of the mould. In Example 2, the binder in the thicker layer comprises phenol-formaldehyde and urea-formaldehyde resins. The thick layer is formed from slurry, and is then dried and coated with a paste of zircon flour, dextrin, linseed oil, bentonite clay, sodium alginate and water.