Calcium, barium or strontium carbonate granulation for use in glass mfr. - by mixing powder with binder, drying and calcining opt. without contact with inorganic refractory material, to avoid contamination

摘要

Granulation of CaCO3, BaCO3 or SrCO3 (MCO3 with M = Ca, Ba or Sr) comprises (a) granulating MCO3 in the presence of a binder (I) and opt. water; (b) opt. drying; and (c) opt. high temp. treatment (calcination), without the MCO3 coming into contact with inorganic refractory material (II) in any stage. (I) is pref. used in amt. of 0.05-5 (wt.)% (dry basis). (I) is pref. alkali hydroxide, aq. alkali hydroxide soln., water glass, silicate ester, starch, natural potato starch, dextrin, cold-soluble potato or wheat starch, PVA and/or Na poly(meth)acrylate, pref. a mixt. of (aq.) alkali hydroxide (soln.) and Na polyacrylate (IA). MCO3 is pref. granulated in a high speed mixer, granulation mixer or on a granulating pan; and dried at 100-250 deg.C and calcined, if necessary, in a drum or fluidised bed drier. USE/ADVANTAGE - The granulate is used in the mfr. of glass (claimed), e.g., the front glass of TV equipment, which can absorb X-rays from CRT's. The process is simple and gives a granulate abs. free from (II), as required for this purpo