Patent ID: 8906201

Claim:
A method of manufacturing paper or cardboard, which comprises: a) diluting paper or board pulp with an aqueous composition, and b) removing water from the pulp by draining, pressing, and drying, wherein the aqueous composition is prepared by: i) adding calcium oxide or calcium hydroxide slurry to flowing and almost fibreless process water or a mixture of almost fibreless process water and pure water in a content that is at least 0.01% calculated from the weight of the solid matter of the paper or board pulp to form a mixture, ii) simultaneously adding carbon dioxide to the flowing and almost fibreless process water or mixture of almost fibreless process water and pure water, so that the pH of the mixture remains at 6.0-8.3, whereby a colloidal portion and a sediment are formed, and iii) separating the colloidal portion from the sediment to yield the aqueous composition.