Echeverry-Vargas Luver, Estrada Darwin, Gutierrez Leopoldo
Department of Metallurgical Engineering, Universidad de Concepción, Concepción 4070371, Chile.
Water Research Center for Agriculture and Mining (CRHIAM), Universidad de Concepción, Concepción 4070411, Chile.
Polymers (Basel). 2022 Sep 5;14(17):3680. doi: 10.3390/polym14173680.
Process water used in mineral processing operations corresponds to water recovered from the thickeners and tailings dams, containing residual reagents such as hydrolyzed polyacrylamides (HPAMs). These polymers depress the flotation of different minerals, and their effect on molybdenite has been experimentally demonstrated. The objective of this work was to study the interactions between a segment of a HPAM with the face and edge of molybdenite. The sigma profile, the radial distribution functions of the HPAM, and the orientation and atomic density profiles of water molecules on the face and edge surfaces of molybdenite were calculated. The results obtained from molecular dynamics simulations showed that the interactions between the HPAM and molybdenite are mainly explained by the interactions of the amide group with the faces and edges of the mineral. Molecular dynamics simulations also showed that the HPAM molecule rearranges in such a way that the amide group moves towards the molybdenite face or edge, and the carboxylate group moves away from the mineral surface. The results obtained in the simulations showed that the interactions of the HPAM with the molybdenite edge are slightly stronger than the interaction of this molecule with the mineral face. Simulations demonstrated that the presence of the sodium and hydroxide ions reduces the concentration of HPAM around the face and edge surfaces, which is expected to affect HPAM adsorption on molybdenite. The conclusions obtained through molecular dynamics simulations are in line with the results obtained in previous studies carried out at a macroscopic scale, which reported that HPAMs adsorb onto molybdenite particles and reduce their hydrophobicity.
矿物加工操作中使用的工艺水对应于从浓密机和尾矿坝回收的水，其中含有水解聚丙烯酰胺（HPAM）等残留试剂。这些聚合物会抑制不同矿物的浮选，并且它们对辉钼矿的影响已通过实验得到证实。这项工作的目的是研究HPAM的一个片段与辉钼矿的表面和边缘之间的相互作用。计算了HPAM的西格玛分布、径向分布函数以及辉钼矿表面和边缘表面上水分子的取向和原子密度分布。分子动力学模拟得到的结果表明，HPAM与辉钼矿之间的相互作用主要由酰胺基团与矿物表面和边缘的相互作用来解释。分子动力学模拟还表明，HPAM分子会重新排列，使得酰胺基团朝着辉钼矿表面或边缘移动，而羧酸根基团则远离矿物表面。模拟结果表明，HPAM与辉钼矿边缘的相互作用略强于该分子与矿物表面的相互作用。模拟表明，钠离子和氢氧根离子的存在会降低HPAM在表面和边缘表面周围的浓度，这预计会影响HPAM在辉钼矿上的吸附。通过分子动力学模拟得出的结论与之前在宏观尺度上进行的研究结果一致，之前的研究报告称HPAM会吸附在辉钼矿颗粒上并降低其疏水性。
