METHOD IN THE MANUFACTURE OF LIGNOCELLULOSIC FIBREBOARD

1319422 Making fibreboard MOTALA VERKSTAD AB 19 April 1971 [29 April 1970] 26947/71 Heading B5A A method of manufacturing lignocellulosic fibreboard comprises suspending a wet pulp in a gas from which it sediments to form a pulp web, the moisture ratio of the pulp having been rendered uniform before the web is formed. In Fig. 1 the pulp is prepared in a digester, 1, refiner 5, and a cyclone 7 before it is dewatered to a uniform moisture ratio in a press 11. The pulp is then passed to a shredder 13 and bunker 15 before moving to a forming machine 22 where the gas/fibre suspension is formed. In the machine 22 the fibres sediment on to a surface 25, are compressed at 26, sawn into sheets at 27, and pressed at 30. In Fig. 2, not shown, water is added to the pulp before compression, at 26. The pulp layer on the surface 25 can be machined to a uniform thickness by a cutter (36) in Fig. 3, not shown. In Fig. 4, not shown, a belt weigher (38) feeds pulp to the machine 22 as a function of the speed of movement of the surface 25. The arrangement in Fig. 5, not shown, includes a tank (44) to receive water from the dewatering apparatus 11, which operates at the same pressure as the apparatus 11. In Fig. 6, not shown, the cyclone 7 is placed after the dewatering apparatus 11, and in Fig. 7, not shown, a pulp container (30) is connected to the dewatering apparatus (48). Colouring agents and insecticides can be added to the fibreboard.