Characterizing latency removal in mechanical pulping processes part I: Kinetics

Latency removal in the mechanical pulping process occurs in a continuous stirred-tank reactor and non-ideal mixing lowers the performance. In order to optimize the latency removal process and reduce the energy consumption in the operation, a kinetic study was carried out. In the study, the phenomenon of latency and knowledge related to latency removal were critically reviewed and discussed. Latency removal was characterized by the change of Canadian Standard Freeness (or freeness), and its dependences on treatment conditions, i.e., disintegration temperature, power input, pulp consistency and time, were determined. Kinetic models of latency removal for secondary refiner thermomechanical (TMP) and bleached chemithermomechanical (BCTMP) pulps have been developed, which were based on the rate of latency elimination characterized by the decrease of freeness.