Hartmann Robert, Rinne Tommi, Serna-Guerrero Rodrigo
Department of Chemical and Metallurgical Engineering, School of Chemical Engineering, Aalto University, P.O. Box 12200, Aalto 00076, Finland.
Langmuir. 2021 Feb 23;37(7):2322-2333. doi: 10.1021/acs.langmuir.0c03131. Epub 2021 Feb 5.
In the search for more sustainable alternatives to the chemical reagents currently used in froth flotation, the present work offers further insights into the behavior of functionalized cellulose nanocrystals as mineral hydrophobization agents. The study corroborates that hexylamine cellulose nanocrystals (HACs) are an efficient collector for the flotation of quartz and also identifies some particular characteristics as a result of their colloidal nature, as opposed to the water-soluble reagents conventionally used. To investigate the individual and collective effects of the frother and HACs on the attachment of particles and air bubbles, an automated contact timer apparatus was used. This induction timer measures particle-bubble attachment probabilities () without the influence of macroscopic factors present in typical flotation experiments. This allowed the study of the combined influence of nanocellulose and frother concentration on for the first time. While HACs readily adsorb on quartz modifying its wettability, the presence of a frother leads to a drastic reduction in up to 70%. The improved recovery of quartz in flotation cells might thus be attributed to froth stabilization by HACs, perhaps acting as a Pickering foam stabilizer. Among the main findings, a tendency of HACs to form mineral agglomerates was identified and further explained using the extended DLVO theory in combination with measured adsorption rates in a quartz crystal microbalance. Therefore, this study distinguishes for the first time the antagonistic effect of frothers on and their synergies with HACs on the stabilization of orthokinetic froths through the hydrophobization mechanism unlike those of typical water-soluble collectors.
在寻找比目前用于泡沫浮选的化学试剂更具可持续性的替代品时，本研究进一步深入探讨了功能化纤维素纳米晶体作为矿物疏水化剂的行为。该研究证实，己胺纤维素纳米晶体（HACs）是石英浮选的有效捕收剂，并且还确定了由于其胶体性质而产生的一些特殊特性，这与传统使用的水溶性试剂不同。为了研究起泡剂和HACs对颗粒与气泡附着的单独和共同影响，使用了自动接触计时装置。该感应计时器测量颗粒 - 气泡附着概率（），不受典型浮选实验中存在的宏观因素影响。这使得首次能够研究纳米纤维素和起泡剂浓度对的综合影响。虽然HACs很容易吸附在石英上改变其润湿性，但起泡剂的存在会导致急剧降低高达70％。因此，浮选槽中石英回收率的提高可能归因于HACs对泡沫的稳定作用，也许是作为一种皮克林泡沫稳定剂。在主要发现中，确定了HACs形成矿物团聚体的趋势，并结合石英晶体微天平中测量的吸附速率，使用扩展的DLVO理论进一步解释。因此，本研究首次区分了起泡剂对的拮抗作用以及它们与HACs通过疏水化机制对同向运动泡沫稳定的协同作用，这与典型的水溶性捕收剂不同。
