process for improving the characteristics of the raw material of paper pulp obtained mechanically from wood

摘要

Logs 2 are fed through a chamber to be wet ground on a grinding stone 3 dipping into pulp 9 in a pulp pit 4. The pulp is stirred by a stirrer 15 in a pit extension 16 with a baffle 17 and overflows a weir 8 into a channel 10 for extraction through a pump 11. Above-atmospheric pressure in the chamber 12 is maintained by compressed air through a pipe 14 and valve 13 and steam through a pipe 19 and valve 18. Aqueous filler suspension and water are supplied as selected through jet pipes 5, 5a, 6 and 7. The heat generated by grinding causes lignin and other thermoplastic substances to become sticky and bind the filler material particles to the wood fibres. IMAGE