GB1442455A - Pigmentary composition - Google Patents

Abstract

1442455 Pigmentary composition T H FERRIGNO 27 July 1973 35976/73 Heading C1A [Also in Division C4] A pigmentary composition comprises agglomerates (size range 20 Á-1 cm.) consisting of 90-99 parts of an anhydrous silicate as defined (size range 2-40 Á) and 1-10 parts of an inorganic binder. The agglomerates may be prepared by mixing, forming and calcining at a temperature sufficient to bind the particles together to give a product with an S.G. of 60- 95% of that of the silicate and a water absorption of less than 10% by weight. The anhydrous silicate as defined may be a naturally occurring mineral e.g. SiO 2 , Be, Mg or Ca silicate or Li, Be, Mg, Ba, Na, K or Ca alumino-silicate or a mixture of these, and may contain up to 10% of associated minerals. Feldspar and mixtures of feldspar and silica are exemplified and claimed and silica is exemplified. Hydrous minerals may be calcined to a substantially anhydrous condition. The inorganic binder may be a glassy phosphate with 4-100 P atoms per molecule, an expanding lattice montmorillonite, a soluble silicate of Li, Na or K or a mixture of these, bentonite being preferred. The agglomerates may be prepared by mixing and forming in one step, e.g. in a rotating disc pelletizier or a drum tumbler or in two steps by mixing conventionally followed by any method offorming, e.g. extruding, compacting, tableting, spray drying or other procedures, water may be added as required. Calcining may be carried out by any method which prevents the agglomerates fusing together, a fluidized bed furnace is preferred for smaller agglomerates. The preferred form of the final product is a hollow spheroid and it may be used as a white pigment.