Kinetic Model for Flocculation with Polymers

A kinetic model for flocculation with synthetic polymers has been developed and tested on systems containing precipitated heavy metal hydroxides. The rate of flocculation is shown to be second order in particle concentration and to decrease with time as adsorbed polymer loops become shorter. Floc breakup is exhibited above a definite energy level. Model parameters and particle aggregation rate are found to depend on metal species. The study indicates that flocculation should be accomplished in as short a time and therefore at as high a velocity gradient as possible, while remaining below the critical energy level for floc breakup. The new model was developed after a model discrimination and evaluation procedure showed existing kinetic flocculation models to be inadequate for the system under study. All models were evaluated in batch experiments performed on simulated mine drainage, which had undergone conventional lime neutralization. The new model is shown to be applicable to actual minewaters, and an example of its use to calculate required flocculation time is provided.