Abstract: A method of blending a fine precipitated calcium carbonate (PCC) filler with larger PCC, the resulting blend to be used alone or in conjunction with a ground carbonate, clay or other filler, resulting in improved porosity by the lowering of the porosity of supercalendered paper, thereby imparting improved and offset printability. The fine PCC can be ultrafine PCC filler which then is blended with other fillers including but not limited to pigments. These fillers which are blended with the fine PCC include commercial and experimental PCC and commercial clays. Ultrafine PCC has agglomerates of small, discrete particles. Ultrafine PCC for use in the invention has a specific surface area of about 20 m2/g as measured by BET gas adsorption. As measured by a sedigraph, the average size of these agglomerates is from 0.4 to 1.1 microns.

Abstract: A method of blending a fine precipitated calcium carbonate (PCC) filler with larger PCC, the resulting blend to be used alone or in conjunction with a ground carbonate, clay or other filler, resulting in improved porosity by the lowering of the porosity of supercalendered paper, thereby imparting improved and offset printability. The fine PCC can be ultrafine PCC filler which then is blended with other fillers including but not limited to pigments. These fillers which are blended with the fine PCC include commercial and experimental PCC and commercial clays. Ultrafine PCC has agglomerates of small, discrete particles. Ultrafine PCC for use in the invention has a specific surface area of about 20 m2/g as measured by BET gas adsorption. As measured by a sedigraph, the average size of these agglomerates is from 0.4 to 1.1 microns.

Abstract: An improved air cleaning device is provided for removing solid particulate matter from a contaminated air stream. The air cleaning device comprises a main housing having an air inlet and an air outlet. The air cleaning device further includes a wash section having a tubular housing with its upper end forming the contaminated air inlet and its lower end being open to the interior of the housing. A wash liquid disperser adjacent the upper end of the wash section housing injects a wash fluid into the contaminated air stream, while a venturi downstream from the dispenser accelerates the contaminated air stream now intermixed with the wash liquid downwardly through the wash section housing. The venturi comprises a pair of baffles each having an upper edge portion, a lower edge portion and forming a convex surface therebetween. The baffles are attached to facing walls in the wash section housing and so that the convex surface of the baffles face or protrude toward each other.