Pérez Kevin, Toro Norman, Jeldres Matías, Gálvez Edelmira, Robles Pedro, Alvarado Omar, Toledo Pedro G, Jeldres Ricardo I
Departamento de Ingeniería Química y Procesos de Minerales, Facultad de Ingeniería, Universidad de Antofagasta, Av. Angamos 601, Antofagasta 1240000, Chile.
Faculty of Engineering and Architecture, Universidad Arturo Prat, Almirante Juan José Latorre 2901, Antofagasta 1244260, Chile.
Polymers (Basel). 2022 Mar 29;14(7):1381. doi: 10.3390/polym14071381.
The resistance of kaolin aggregates to shearing in water clarification and recovery operations is a critical input in designing thickener feed wells. A recently formulated but already available criterion is used to determine the shear strength of flocculated kaolin aggregates. The flocculant is a high molecular weight anionic polyelectrolyte. The resistance of the aggregates is evaluated as a function of flocculation time, flocculant dosage, and water quality. The determination is based on a standardized experimental method. First, the time evolution of the average size of kaolin flocs is measured when aggregates are exposed to incremental shear rates from a predetermined base value. Then, the results are fitted to a pseudo-first-order model that allows deriving a characteristic value of the shear rate of rupture associated with the upper limit of the strength of the aggregates. In seawater, at a given dose of flocculant, the strength of the aggregates increases with time up to a maximum; however, at longer times, the resistance decreases until it settles at a stable value corresponding to stable aggregates in size and structure. A higher flocculant dosage leads to stronger aggregates due to more bridges between particles and polymers, leading to a more intricate and resistant particle network. In industrial water with very low salt content, the resistance of the kaolin aggregates is higher than in seawater for the same dose of flocculant. The salt weakens the resistance of the aggregates and works against the efficiency of the flocculant. The study should be of practical interest to concentration plants that use seawater in their operations.
高岭土聚集体在水澄清和回收操作中对剪切的抗性是设计浓密机进料井的关键输入参数。一种最近制定但已可用的标准用于确定絮凝高岭土聚集体的抗剪强度。絮凝剂是一种高分子量阴离子聚电解质。聚集体的抗性作为絮凝时间、絮凝剂用量和水质的函数进行评估。该测定基于标准化实验方法。首先，当聚集体暴露于从预定基准值开始递增的剪切速率时，测量高岭土絮体平均尺寸的时间演变。然后，将结果拟合到伪一级模型，该模型允许推导出与聚集体强度上限相关的破裂剪切速率的特征值。在海水中，在给定的絮凝剂剂量下，聚集体的强度随时间增加直至达到最大值；然而，在更长的时间后，抗性会降低，直到它稳定在一个与尺寸和结构稳定的聚集体相对应的稳定值。较高的絮凝剂用量会导致聚集体更强，因为颗粒与聚合物之间形成了更多的桥，从而形成了更复杂且抗性更强的颗粒网络。在盐含量极低的工业用水中，对于相同剂量的絮凝剂，高岭土聚集体的抗性高于海水中的抗性。盐会削弱聚集体的抗性，并对絮凝剂的效率产生不利影响。该研究对于在其操作中使用海水的选矿厂应具有实际意义。
