Impact of preflocculation on scroll decanter centrifuge separation performance

Industrial scroll decanter centrifuge (SDC) separation of the solids in fluid fine tailings (FFT) which have particles 10 μm and smaller in size require flocculant addition. Accordingly, the mechanism in the centrifuge is flocculation of the fine solid particles followed by sedimentation. Thus, feeding preflocculated material obviates the flocculation step inside the SDC resulting in improved process efficiency by reducing the power consumption and increasing the throughput capacity of each SDC. This work evaluated the separation performance of the SDC using inline static mixers to preflocculate oil sands FFT containing solids, 90 mass% of which are < 9 μm in size. The minimum G‐forces required to achieve the industry benchmarks of < 1 mass% solids in the centrate water and > 97 % fines capture rate were 750 G without preflocculation and 400 G with preflocculation. Since power consumption by the SDC, as expected, was directly proportional to the G‐force, the savings in power due to preflocculation amounted to 47 %. Preflocculation increased SDC throughput capacity by up to 50 %. Operating at lower G‐force has the additional benefits of protecting the high‐capital‐cost SDC machine and reducing ambient noise levels.