Method for burning secondary sludge in a recovery boiler

摘要

A method for burning secondary sludge in a recovery boiler, in which method secondary sludge is mixed with black liquor. According to the method, an alkali is added to the secondary sludge so as to obtain a mixture having a pH of over 7, whereafter the mixture of alkali and secondary sludge is heated to a temperature of over 80 DEG C. and kept at this temperature for over 30 minutes. Thereafter the heat treated mixture of alkali and secondary sludge is supplied to the thick end of a black liquor evaporation plant.