Abstract
Chips from softwood and hardwood purchased and separately stored in outside piles of 400m3 during 12 months for the purpose of testing the deterioration of their quality were subjected to pulping processes on the laboratory basis, and were evaluated with regard to pulp yield of woods per m3 mechanical strength, brightness and bleachability of pulps.
It was concluded that:
1) Notable deterioration of chips in summer with high temperature (38°C in August and September at the deeper inside of the piles) was brought about, while the deterioration during winter season (-4°C in January and February) was found to be almost negligeable. It is, therefore, desirable to avoid outside storage of chips in summer as much as posible.
2) Under the greater influences of atmospheric and climatic conditions the degree of deterioration of chips at the surface layer of the piles had been larger compared with that of chips deep inside of the piles.
3) Decrease in volumetric weight of chips and the decrease in brightness, mechanical strength and bleachability of pulps had been caused by the outside storage of chips, the negative effets on volumetric weight of chips and bleachability of pulps being especially remarkable, and thus requiring more quantity of bleaching agent with inevitable result of decreasing pulp yields.
In regard to the future aspect with greater necessity of storing chips in outside piles, considerations for suppressing deterioration of chips would be very important problem to tackle with.
