The mathematical model for acid sulphite pulping process is represente
d by a linear logarithmic straight line dependence of the main charact
eristics of pulping, i.e. yield and lignin content in pulp versus time
and temperature parameters, both determined by the H-factor. The loga
rithmic plot of the ratio and product of the mentioned characteristics
and parameters of pulping is linear for the content of lignin in pulp
lower than 15 % and the value of H-factor higher than 100. The most s
uitable way for the calculation of the main characteristics of pulping
is using a power form of the logarithmic straight line dependence of
the ratio yield/lignin vs. lignin content, yield/H-factor vs. H-factor
, lignin/H-factor vs. H-factor and their mathematical equivalents, i.e
. reciprocal ratios and/or products. Individual constants of the model
for sulphite pulping of spruce wood expressed by means of a logarithm
ic straight line equation for dependence studied, are summarized in Ta
bles.