Abstract: The invention relates to a jet mill of modular design for the comminution of powdery materials. An inner pulverizing casing made entirely of wear-resistant material is freely mounted in an outer casing pressure vessel.

Abstract: The invention relates to a method for the surface treatment of a titanium dioxide that leads to pigments with improved retention and improved opacity, where consistently high opacity can be obtained using less pigment. The method is characterised in that an aluminium component and a phosphorus component are first added to a TiO2 suspension, during which process its pH value does not drop below 10. The pH value of the suspension is subsequently lowered to below 9 by adding an acid component. The pigment produced by the method according to the invention is eminently suited to use in decorative laminating paper.

Abstract: The invention relates to a method for the post-treatment of titanium dioxide, in order to produce particularly weather-resistant titanium dioxide pigments with good optical properties. The method is characterized in that, together with the hydrous oxides of tin and zirconium, at least one other from the group comprising aluminium, silicon and titanium is additionally precipitated onto the particle surface. The post-treatment components are added to the aqueous TiO2 suspension either in the acidic range (pH value of 3 at most) or in the alkaline range (pH value of 10 at least). The pH value is subsequently set to between 6 and 8. Final tempering of the pigment at elevated temperatures from over 125° C. to up to 500° C. can improve the tone b. The pigment is particularly suitable for use in paints, coatings and plastics.

Abstract: The quality of distribution of pigments in a matrix is estimated by measuring the reflectivity of a sample of the pigmented matrix at a shorter and a longer wavelength, and calculating a function of the two measurements. A ratio of the normalized reflectivity for broad short and long wavelength bands is the preferred function.