METHOD FOR MANUFACTURE OF PULP AND BLACK LYE RECYCLING Russian patent published in 2009 - IPC D21C11/00 D21C11/04 D21C11/10 D21C3/02 

FIELD: textile fabrics, paper.

SUBSTANCE: methods are related to manufacture of pulp from grass raw material and recycling of black lye, especially the one produced in process of pulp boiling and may be used in pulp and paper industry. Methods of black lye recycling are intended for production of inorganic material and synthesis-gas. Methods for recycling of black lye include supply of heated fluidising gas into reactor process area provided with mass of loose material from oxide of alkali earth metal or containing oxide of this metal. Vortical flow of loose material is generated in this area of reactor so that loose material takes the shape of compact strip and circulates around axis of mentioned process area in the form of turbulent flow, creating fluidisated later. At that fluidising gas contains substoichiometric amount of oxygen for partial oxidation of black lye organic material and for transformation of other organic material of black lye into synthesis-gas. Then black lye is supplied into compact strip of loose material so that it is heated up to the temperature of 650-725°C and gasified. From this layer synthesis-gas is extracted in the form of spent gas, as well as inorganic material in the form of hard substance. Method may be used separately or as part of method for transformation of grass raw material into pulp for production of paper or cardboard. Method for production of pulp from grass raw material includes the following stages: (a) digestion of mentioned raw material with application of white lye that mainly contains sodium hydroxide and calcium hydroxide in amount sufficient for complete transformation of silica available in mentioned raw material into calcium silicate; (b) extraction of pulp and black lye free from free silica; (c) heating of black lye in reactor with fluidisated layer that contains calcium oxide for catalytic transformation of organic substance contained in mentioned black lye into gas and for production of regenerated hard substances, which include precious sodium components of mentioned white lye and calcium oxide; and regeneration of mentioned white lye with application of mentioned regenerated hard substances.

EFFECT: higher safety of processes due to exclusion of explosions, their efficiency, lower environmental pollution and equipment contamination, and also possibility to recycle straw of wheat, rice and other materials with high silica content without production of black lye, which is difficult to be recycled.

39 cl, 5 dwg