Larch Biorefinery:Technical and Economic Evaluation.

Inthis study a forest biorefinery concept based on larch woodwas technically and economically evaluated. Two slightly differentcases of a larch-based biorefinery were compared to conventional kraftpulping. The wood chips of Larix sibirica(Lebed.) were pre-extracted (PE) and washed with water prior topulping, in order to generate an additional sugar side-stream. Thesugars were hydrolyzed into monosugars, which were then fermentedby Bacillus coagulansinto lactic acid.The lactic acid needs to be purified before sold to the market. Bypulping the pre-extracted wood chips with anthraquinone (AQ) and polysulfide(PS), the pulp yield loss was reduced. The pulp was then bleached(O-D0-Ep-D1-P). The products of this larch biorefinery are bleachedsoftwood pulp and lactic acid. Three process cases were simulated:conventional kraft pulping, PE-PSAQ with 0.5% PS, and PE-PSAQ with2% PS, in terms of mass and energy balances. Considering the availabilityof larch resources, this kind of a biorefinery could suitably be locatedin Siberia, Russia. Market prices were collected, and based on thesimulation results, cash flows were determined. Sensitivity analysiswas carried out, and investment costs were estimated. Based on thesimulation with the addition of a lactic acid production line to anexisting pulp mill, the payback time for the investment costs wouldbe about 16 months. [ABSTRACT FROM AUTHOR]