Pulgar Francisco, Ayala Luis, Jeldres Matías, Robles Pedro, Toledo Pedro G, Salazar Iván, Jeldres Ricardo I
Departamento de Ingeniería Química y Procesos de Minerales, Facultad de Ingeniería, Universidad de Antofagasta, P.O. Box 170, Antofagasta 1240000, Chile.
Faculty of Engineering and Architecture, Universidad Arturo Prat, Almirante Juan José Latorre 2901, Antofagasta 1240000, Chile.
Polymers (Basel). 2021 Nov 25;13(23):4108. doi: 10.3390/polym13234108.
Seawater treated with lime and sodium carbonate in different proportions to reduce magnesium and calcium contents is used in flocculation and sedimentation tests of artificial quartz and kaolin tailings. Solid complexes were separated from water by vacuum filtration, and factors such as lime/sodium carbonate ratio, kaolin content, flocculation time, and flocculant dose are evaluated. The growth of the aggregates was captured in situ by a focused beam reflectance measurement (FBRM) probe. Solid magnesium and calcium complexes are formed in raw seawater at pH 11, impairing the performance of flocculant polymers based on polyacrylamides. The results show that the settling rate improved when the treatment's lime/sodium carbonate ratio increased. That is, when a greater removal of magnesium is prioritized over calcium. The amount of magnesium required to be removed depends on the mineralogy of the system: more clay will require more significant removal of magnesium. These results respond to the structural changes of the flocs, achieving that the more magnesium is removed, the greater the size and density of the aggregates. In contrast, calcium removal does not significantly influence flocculant performance. The study suggests the necessary conditions for each type of tailing to maximize water recovery, contributing to the effective closure of the water cycle in processes that use seawater with magnesium control.
用石灰和碳酸钠按不同比例处理以降低镁和钙含量的海水用于人造石英和高岭土尾矿的絮凝和沉降试验。通过真空过滤将固体络合物与水分离,并评估石灰/碳酸钠比例、高岭土含量、絮凝时间和絮凝剂剂量等因素。通过聚焦光束反射测量(FBRM)探头原位捕获聚集体的生长情况。在pH值为11的原海水中会形成固体镁和钙络合物,这会损害基于聚丙烯酰胺的絮凝剂聚合物的性能。结果表明,当处理的石灰/碳酸钠比例增加时,沉降速率提高。也就是说,当优先考虑更多地去除镁而不是钙时。需要去除的镁量取决于系统的矿物学:更多的粘土将需要更大量地去除镁。这些结果对应于絮凝物的结构变化,即去除的镁越多,聚集体的尺寸和密度就越大。相比之下,去除钙对絮凝剂性能没有显著影响。该研究提出了每种类型尾矿实现最大程度水回收的必要条件,有助于在控制镁含量的海水使用过程中有效封闭水循环。