Partial borate autocausticizing trial increases capacity at Swedish mill

A full-scale partial borate autocausticizing trial has been running continuously and successfully since November 2002 at the Stora Enso Norrsundet mill in Sweden. The objective has been to off-load the lime kilns and reduce the amount of purchased lime and subsequent lime mud disposal costs. The total lime requirement has been reduced by about 7% while the autocausticizing level averaged around 9%-11% over this period. Overall, the presence of sodium borate in the liquors had little effect on the mill operations and the pulp properties and quality were unaffected. Results suggest that borates may enhance the pulp yield.