UNIFORMITY OF SODIUM-SULFITE DISTRIBUTION IN IMPREGNATED BLACK SPRUCEWOOD CHIPS

The distribution of sodium sulphite was non-uniform throughout art imp regnated black spruce wood chip following passage through a screwfeede r with compression ratio of 3:1. In particular concentrations of sulph ite and bound sulphur were higher in earlywood than in latewood becaus e of morphological differences. Bound sulphur was more uniformly distr ibuted in a more destructured chip than in a less destructured one. Th e greater destructuring was achieved by using a screwfeeder with a hig her compression ratio (5:1 rather than 3:1) which increased the sodium sulphite uptake by 20 to 48%, depending on chip thickness. The unifor mity of sulphite distribution was also improved by prolonging the resi dence time of impregnated chips in the preheater.