A system and a method for producing dewatered fine tailings from tailings resulting from a process for recovering bitumen from oil sand. The method includes separating the tailings into fine tailings and coarse tailings, partially dewatering th e fine tailings, chemically treating the partially dewatered fine tailings, and dewatering the chemicall y treated partially dewatered fine tailings in a high density thickener apparatus, thereby producing the dewatered fine tailings. The system includes an apparatus for separating the tailings into the fine tailings and the coarse tailings, an apparatus for partially dewatering the fine tailings, a chemical treatment subsystem for chemically treating the partially dewatered fine tailings, and a high density thickener apparatus for dewatering the chemically treated partially dewatered fine tailings to produce the dewatered fine tailings.