CELLULOSE PRODUCTION PROCESS Russian patent published in 2007 - IPC D21C1/06 D21C3/02 

FIELD: paper-and-pulp industry.

SUBSTANCE: invention relates to production of fibrous intermediate products from rice straw. The latter is first treated with NaOH solution, 20-60 g/L, in presence of anthraquinone at temperature not lower than 70°C for at least 20 min in order to remove silica. Anthraquinone is added in amount at least 0.01% based on dry weight of cellulose-containing raw material. Resulting pulp is separated from alkali solution and subjected to alkali digestion in NaOH solution ensuring uptake of 8-14% of dry raw material for at least 60 min.

EFFECT: increased yield of desired product, reduced consumption of reagents in digestion operation, and improved quality of product due to retention of hemicellulose complex as well as partial removal of lignin.

2 cl, 3 tbl