Abstract: A method of making a purified precipitated calcium carbonate from lime mud can include admixing a lime mud cake with water and sodium carbonate to form a first slurry; heating the first slurry under conditions to age the slurry and form one or more of pirssonite, shortite, and gaylussite; separating a solid portion from the aged slurry; washing the solid portion under conditions sufficient to decompose the one or more of pirssonite, shortite, and gaylussite to a CaCO3 solid fraction and Na2CO3 solid fraction and to remove sodium salts; and admixing the CaCO3 solid fraction with water and a dispersant to disperse the CaCO3 solid fraction in water and form a dispersed slurry having a Brookfield viscosity of less than about 1000 cps at 100 rpm, thereby producing a dispersed slurry containing the purified precipitated calcium carbonate.

Abstract: The present invention relates to a paper or paperboard substrate containing fiber-filler complexes as well as methods of making and using the same.