Shear-induced floc structure changes for enhanced dewatering of coal preparation plant tailings
Shear-induced floc structure changes for enhanced dewatering of coal preparation plant tailings
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DOI：
10.1016/j.cej.2011.06.082
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发表时间：
2011-08-15
影响因子：
15.1
通讯作者：
Ozdemir, Orhan
中科院分区：
文献类型：
--
作者：
Ofori, Philip;Nguyen, Anh V.;Ozdemir, Orhan
处理和处置含有胶体颗粒物质的工业废浆料，特别是具有高比例粘土材料的煤和矿物加工厂尾矿，提出了重大挑战。为了开发有效的处置方法，需要更好地了解絮凝体结构，以促进更好的水回收和更高的沉积物密度，在沉降和固结絮凝尾矿。本文研究了絮凝体结构对煤尾矿脱水的影响，以及剪切作用下絮凝体网络结构的改变对附加沉积物固结和密实化的影响。采用四种真实的尾矿和一种高分子阴离子絮凝剂。絮凝试验在可重复的流体动力学条件下以分批模式进行。絮凝体具有不同尺寸、形状和空隙率的复杂结构。絮凝体的结构进行了表征，采用光散射技术的分形分析和絮凝体的脱水特性进行了研究的沉降速率和泥沙固结。通过激光散射分形分析确定了最佳搅拌速度和絮凝剂用量所需的絮体的分形维数大于2的紧凑结构的生产。据确定，絮凝过程中的水动力条件有一个深刻的影响絮凝沉降速率，并在较小程度上沉积物固结。低混合速度产生大的絮凝体与高沉降速率，而非常高的混合速度在絮凝过程中导致不可逆的絮凝体降解，导致沉降速率大大降低，一些额外的沉积物固结。剪切预沉降絮凝物的应用导致显着的额外的沉积物固结的尾矿样品和絮凝剂的研究。这种方法将允许絮凝被优化用于快速沉降，随后向沉降的沉积物施加剪切以促进絮凝物间和絮凝物内液体的去除，从而改善固结和沉积物密度。皇冠版权所有（C）2011由Elsevier B.V.出版。保留所有权利。
The handling and disposal of industrial waste slurries containing colloidal particulate matter, with particular reference to coal and mineral processing plant tailings with a high proportion of clay materials present significant challenge. To develop effective disposal methods requires an improved understanding of floc structure that promote better water recovery and higher sediment density during settling and consolidation of flocculated tailings. In this paper, the effect of floc structure on coal tailings dewatering and the impact of shear-induced modification of floc network structure on additional sediment consolidation and densification have been examined. Four real tailings and a high molecular weight anionic polymeric flocculant were used. Flocculation tests were conducted under reproducible hydrodynamic conditions in batch mode. Flocculated aggregates have complex structures with different sizes, shapes and voidages. The structures of the flocs were characterised by fractal analysis using light scattering technique and the dewatering characteristics of the flocs were investigated in terms of settling rates and sediment consolidation. The fractal analysis by laser scattering identified optimum mixing speed and flocculant dosage required for the production of flocs with compact structure of fractal dimensions greater than 2. It was determined that hydrodynamic conditions during flocculation have a profound impact on floc settling rates and to a lesser extent sediment consolidation. Low mixing speeds produced large flocs with high settling rates, while very high mixing speed during flocculation resulted in irreversible floc degradation leading to much reduced settling rates with some additional sediment consolidation. Application of shear to pre-sedimented flocs resulted in significant additional sediment consolidation for the tailings samples and flocculants studied. This approach would allow flocculation to be optimised for fast settling with subsequent application of shear to the settled sediment to promote the removal of inter and intra-floc liquor to improve consolidation and sediment density. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.