METHOD FOR PRODUCING FIBROUS SEMI-FINISHED PRODUCT FROM PLANT RAW MATERIALS Russian patent published in 2023 - IPC D21C1/06 

FIELD: pulp and paper industry.

SUBSTANCE: invention is related to manufacturing of fibrous semi-finished products and can be used in the pulp and paper industry in production of disposable tableware and in production of various types of paper and cardboard. The method involves steaming vegetable raw materials in form of chopped rye and wheat straw with live steam at temperatures up to 98°C for 20-60 minutes in presence of a surfactant OP-7 or OP-10 with a consumption of 0.5-0.9 kg/t by weight of absolutely dry raw materials, then the cut is impregnated with a solution containing urea or potassium carbonate, at a temperature of 80-95°C for 20-40 minutes, the impregnating solution is separated, the material is saturated with a solution of sodium or potassium hydroxide at a consumption rate of 10-30 kg/t based on the mass of absolutely dry raw materials. After which thermochemical treatment of the cut is carried out at a temperature of 100-130°C for 10-20 minutes in the reactor, after the heat treatment time has elapsed, the contents of the reactor are acidified with a solution of acid salts of sulfurous or orthophosphoric acid with a consumption of 3.5-6.5 kg/t by weight of absolutely dry raw materials to a pH of no more than 7.0. Then the cut is dehydrated to a concentration of 60-70% with separation of the liquid phase, diluted with water, ground and sorted.

EFFECT: invention makes it possible to reduce the environmental impact of the harmful effects of the spent alkaline solution from a thermochemical operation and at the same time increase the yield of the target product.

5 cl, 6 ex, 1 tbl