| 摘要 |
364,756. Re covering clean pulp from old paper. WEBER, R., Drentwede, Bremen, Germany. Nov. 17, 1930, No. 34557. Convention date, Nov. 18, 1929. [Class 96.] Clean paper pulp is recovered from old printed paper by a cold process by treating with causticizing sludge, obtained as a waste product in the causticizing of soda, the pulp then being washed ; carnallite waste iquors may be added to the causticizing sludge, and the causticizing sludge or the carnallite liquor may be prepared from its constituents. The sludge may be obtained in the causticizing of pure sodium carbonate or in the causticizing of the residue obtained by evaporating and igniting the boiling liquors used in the manufacture of soda pulp or sulphate pulp. When carnallite waste liquor is added, magnesium hydroxide is formed, the colloidal nature of which assists removal of the printer's ink. In an example, 1000 kg. of old printed paper is disintegrated in a Hollander and 300-500 litres causticizing sludge added. After 1-2 hours the pulp is washed, preferably by means of a washing drum which revolves in the pulp and is covered with a fine sieve. |
