Abstract: A method for producing structured calcium carbonate pigments for coating paper is disclosed. An aqueous slurry of anionically dispersed calcium carbonate particles is formed at 1 to 30 percent solids. A low-molecular-weight cationically charged aggregating agent is then added to the slurry to selectively aggregate fine and ultra-fine particles. The resultant aggregates are of larger mean particle size than the mixture of particles in the original slurry and contain little or no fine and colloidal particles. The net charge present on the aggregated particles is lower than that of the original mineral particles. The low solids suspension of the aggregated mineral particles is then dewatered, or increased in solids to form a slurry with a solids content greater than 60 percent by weight.

Abstract: A method for producing bulking and opacifying kaolin fillers for filling cellulosic products is disclosed. An aqueous slurry of anionically dispersed kaolin particles is formed at 1 to 30% solids. A low-molecular-weight cationic aggregating agent is then added to the dispersed slurry to selectively aggregate fine and ultra-fine particles. The resultant aggregates are of larger mean particle size than the feed material and contain little or no fine and ultra-fine or colloidal particles. The net charge present on the aggregated particles is lower than that of the feed material. The aggregated structure contains within it a labyrinth of internal voids or pores. These mineral aggregates are then of a suitable size and surface charge to be retained well in a fiber web, and provide added bulk and opacity to the cellulosic products.

Abstract: A process is provided for the selective aggregation of the fine and ultrafine particles present in an anionically or cationically dispersed mineral pigment slurry, such that an aggregated structure is formed which contains within it a labyrinth of internal voids or pores, which collectively function as light scattering centers. The aggregates are formed from an assemblage of fine mineral particles, interconnected or bonded together with small quantities of a cationic or anionic polymer or agent of low molecular weight. The resultant aggregates are of larger mean particle size than the feed material and contain little or no fine and colloidal particles. The net charge present on the aggregated particles is lower than that of the feed material. These mineral aggregates are then of a suitable size and surface charge to be retained well in a fiber web by a combination of filtration retention and adsorption retention, and provide added bulk and opacity to the finished sheet of paper.

Abstract: A method is disclosed for producing bulking and opacifying pigments for filling paper by the selective aggregation of fine particles in an anionically or cationically dispersed slurry, such that an aggregated structure is formed which contains within it a labyrinth of internal voids or pores. The aqueous slurry is formed at one to thirty percent solids. A low molecular weight agent of opposite ionic charge is then added to the slurry to selectively aggregate the fine particles present. The resultant aggregates are of larger mean particle size than the feed material and contain little or no fine and colloidal particles. The net charge present on the aggregated particles is lower than that of the feed material.

Abstract: The invention relates to a process for wet grinding of natural and/or synthetic carbonates in wet suspensions in which the viscosity of the mass is decreased and a favorable particle size range distribution is obtained having a small portion of very fine overground particles. The carbonates in the wet grinding are mixed with zeolites to 0.05 to 3.0% by weight based on the dry weight of the carbonates. Chemical dispersants are used to help effect the process.