基于双重絮凝的超细尾砂浓密脱水性能及絮凝机制

Thickening dehydration performance and flocculation mechanism of ultrafine tailings based on dual flocculation

为探索新型絮凝工艺,解决超细尾砂浓密效果不佳的工程难题,引入双重絮凝技术。首先,开展单一絮凝工艺的絮凝沉降实验,分析絮凝剂种类对超细尾砂浓密脱水效果的影响;其次,将不同絮凝剂进行组合,进行双重絮凝实验,研究双重絮凝工艺的影响因素及作用规律,对比2种工艺的絮凝浓密效果;最后,利用聚焦光束反射测量仪(FBRM)和显微镜研究尾砂絮体的粒度与结构变化,探索双重絮凝机制。研究结果表明:在处理铅锌矿的超细尾砂时,双重絮凝工艺能够综合2种聚合物的优点,在絮凝过程的不同阶段运用不同的絮凝机制,显著降低上清液浊度(<30×10^(-6)),并获得较快的尾砂沉降速度(>70 mm/min)和较高的底流质量分数(>65%);双重絮凝的影响因素有絮凝剂种类和絮凝剂添加顺序,“阴离子+阳离子”组合的絮凝浓密效果最优;双重絮凝过程分为初次絮体形成、絮体剪切破坏和二次絮体形成3个阶段,初次阴离子絮凝剂的吸附架桥机制有利于捕捉微细颗粒(<100μm)形成初次絮体,初次絮体剪切破碎后释放部分结合位点,二次阳离子絮凝剂的电中和机制则使破碎絮团增长为可再生的大体积絮团(>1 000μm)。双重絮凝体系在细颗粒捕获和形成大絮体方面具有显著优势。

In order to explore a new flocculation process and solve the engineering problem of poor thickening effect of ultrafine tailings,dual flocculation technology was introduced.Firstly,the flocculation sedimentation experiment of single flocculation process was carried out to analyze the influence of flocculant type on the thickening dehydration effect of ultrafine tailings.Secondly,different types of flocculants were combined to carry out dual flocculation experiment.The influencing factors and action rules of the dual flocculation process were studied.The flocculation thickening effects of the two processes were compared.Finally,the particle size and structure of the tailings were studied by focusing beam reflectometer(FBRM)and microscope,and the flocculation mechanism of the dual polymer was explored.The results show that in the treatment of ultrafine tailings from lead-zinc ore,the dual flocculation process can combine the advantages of the two polymers and apply different flocculation mechanisms at different stages of the flocculation process,which can significantly reduce turbidity of supernatant(<30×10^(−6)),and achieve a faster settling velocity of tailings(>70 mm/min)and a higher mass fraction of underflow(>65%).The influencing factors of dual flocculation are the type of flocculant and the order of adding flocculant,and the flocculation settling effect of"anion+cation"combination is the best.The dual flocculation process is divided into three stages,including primary floc formation,floc shear failure and secondary floc formation.The adsorption bridging mechanism of the primary anionic flocculant is beneficial to capture fine particles(<100μm),and some binding sites on the surface of the particles are released when the floc is broken.The electric neutralization mechanism of the secondary cationic flocculant makes the broken floc grow into a renewable large volume floc(>1000μm).The dual flocculation system has remarkable advantages in trapping fine particles and forming large floc.