The invention discloses a wet-strength wastepaper recycling double-pH-value chemical and mechanical pulping method. The method includes a material preparation section, a
steaming section, a first
extrusion and impregnation chemical and mechanical treatment section, a second
extrusion and impregnation chemical and mechanical treatment section, a latency and re-defibering section and a purification, screening and concentration section. Wet-strength wastepaper
fiber dissociation re-pulping is achieved while original pulp strength is not reduced through the mechanical strong force effect and the
chemical treatment effect. Furthermore, on the two
extrusion and impregnation chemical and mechanical treatment sections connected in series, a
wet strength agent in wastepaper is oxidized under the acid condition firstly,
hydrolysis is further promoted under the alkaline condition, chemical bonding between molecules of the
wet strength agent and between the
wet strength agent and pulp fibers is more effectively damaged, and the
fiber dissociation rate and the re-pulping yield are effectively increased. The problems that the wet-strength wastepaper recycling pulping
dissociation rate is low and strength is greatly decreased are solved, and continuous, large-scale, low-water-consumption and low-energy-consumption
pollution-free and environment-friendly pulping can be achieved.