Fremgangsmåte til fremstilling av et finmalt jordalkimetallpigment
There is disclosed a process for producing a finely ground alkaline earth metal pigment. The process comprises the steps of: (a) preparing an aqueous suspension comprising from 40% to 68 % by weight of a particulate alkaline earth metal compound and including a dispersing agent for the alkaline eart...
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Sprache: | nor |
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Zusammenfassung: | There is disclosed a process for producing a finely ground alkaline earth metal pigment. The process comprises the steps of: (a) preparing an aqueous suspension comprising from 40% to 68 % by weight of a particulate alkaline earth metal compound and including a dispersing agent for the alkaline earth metal compound, in an amount effective to disperse the particles of the particulate material; and (b) subjecting the suspension formed in step (a) to attrition grinding in two or more stages with a particulate grinding medium under conditions such as to yield a product containing less than 70% by weight of alkaline earth metal compound and having a particle size distribution such that at least 90% by weight of the particles have an equivalent spherical diameter smaller than 2 mu m, characterized by the step of: (c) allowing the solids content of the suspension to rise whilst grinding proceeds, without substantially replacing water lost through evaporation under the action of heat contained in the suspension, until the percentage by weight of dry alkaline earth metal compound in the suspension has increased to at least 70% by weight. |
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