Zhang Lei, Liu Shengyu, Sun Beilei, Guo Jianying, Li Bao
College of Mining Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi, China.
Key Laboratory of In-Situ Property-Improving Mining of Ministry of Education, Taiyuan University of Technology, Taiyuan, 030024, China.
J Mol Model. 2024 Sep 10;30(10):329. doi: 10.1007/s00894-024-06129-2.
Extensive studies using a trial-and-error approach have been conducted on low-rank coal flotation collectors. However, screening efficient collectors remains a considerable challenge due to the lack of suitable screening principles. It has proven that polar compounds such as carboxylic acids and esters are effective collectors for low-rank coal flotation. In this work, the effects of carboxylic acid, alcohol, and methyl ester on the floatability of low-rank coal were compared, the flotation performance of the polar collector was evaluated with theoretical calculations, a suitable evaluation parameter was determined and a screening principle based on this parameter was determined. The results show that the enhancement effects of polar collectors on low-rank coal floatability follow the order of methyl decanoate > methyl laurate > methyl octanoate > sec-octanol > methyl oleate (or methyl oleate > sec-octanol) > n-octanoic acid. Compared with the molecular polarity index, the hydrophobicity indices log P and dipole moment cannot be used to accurately evaluate different types of collectors and the same type of collectors, respectively. At room temperature, liquid polar compounds with molecular polarity indices in the range of 6.0 ~ 8.0 kcal/mol effectively enhance the floatability of low-rank coal. The molecular polarity index of the collector is used for the first time to screen effective collectors of low-rank coal in this work. This parameter is anticipated to be highly important for the development and research of low-rank coal and other mineral collectors.
To obtain reasonable and accurate molecular structure, geometry optimization and frequency calculations of the studied collectors were conducted via the Gaussian 09 software package based on density functional theory at the B3LYP/6-311 + G (d, p) level. The integral equation formalism for the polarizable continuum model (IEF-PCM) was utilized with water as the solvent (dielectric constant = 78.36, T = 298 K) for all the calculations. Then, the atomic charge distributions (MPA and NPA) and electrostatic potential maps, the dipole moment and molecular polarity index, and the log P and water solubilities of studied collectors were shown or calculated by Gauss View 5.0, Mutiwfn program and website ( https://www.molsoft.com/mprop/mprop.cgi ), respectively.
针对低阶煤浮选捕收剂，已采用试错法进行了大量研究。然而，由于缺乏合适的筛选原则，筛选高效捕收剂仍然是一项巨大挑战。事实证明，羧酸和酯等极性化合物是低阶煤浮选的有效捕收剂。在本研究中，比较了羧酸、醇和甲酯对低阶煤可浮性的影响，通过理论计算评估了极性捕收剂的浮选性能，确定了合适的评价参数，并基于该参数确定了筛选原则。结果表明，极性捕收剂对低阶煤可浮性的增强效果顺序为：癸酸甲酯＞月桂酸甲酯＞辛酸甲酯＞仲辛醇＞油酸甲酯（或油酸甲酯＞仲辛醇）＞正辛酸。与分子极性指数相比，疏水指数log P和偶极矩分别不能准确评价不同类型的捕收剂和同一类型的捕收剂。在室温下，分子极性指数在6.0～8.0 kcal/mol范围内的液态极性化合物能有效提高低阶煤的可浮性。本研究首次将捕收剂的分子极性指数用于筛选低阶煤的有效捕收剂。预计该参数对低阶煤及其他矿物捕收剂的开发和研究具有重要意义。
为获得合理准确的分子结构，基于密度泛函理论，在B3LYP/6 - 311 + G(d, p)水平下，通过高斯09软件包对所研究的捕收剂进行几何优化和频率计算。所有计算均采用极化连续介质模型的积分方程形式（IEF - PCM），以水为溶剂（介电常数 = 78.36，T = 298 K）。然后，分别通过高斯视图5.0、Multiwfn程序和网站（https://www.molsoft.com/mprop/mprop.cgi）展示或计算所研究捕收剂的原子电荷分布（MPA和NPA）及静电势图、偶极矩和分子极性指数，以及log P和水溶性。
