School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan 410083, People's Republic of China.
State Key Laboratory of Mineral Processing, Beijing General Research Institute of Mining & Metallurgy, Beijing 100160, People's Republic of China.
Langmuir. 2023 Jul 4;39(26):9051-9059. doi: 10.1021/acs.langmuir.3c00678. Epub 2023 Jun 20.
Pyrite, as a disturbing gangue mineral in the beneficiation of valuable sulfide minerals and coal resources, is usually required to be depressed for floating in flotation practice. Specifically, the depression of pyrite is achieved by causing its surface to be hydrophilic with the assistance of depressants, normally with inexpensive lime used. Accordingly, the progressive hydrophilic processes of the pyrite surface in high-alkaline lime systems were studied in detail using density functional theory (DFT) calculations in this work. The calculation results suggested that the pyrite surface is prone to hydroxylation in the high-alkaline lime system, and the hydroxylation behavior of the pyrite surface is beneficial to the adsorption of monohydroxy calcium species in thermodynamics. Adsorbed monohydroxy calcium on the hydroxylated pyrite surface can further adsorb water molecules. Meanwhile, the adsorbed water molecules form a complex hydrogen-bonding network structure with each other and with the hydroxylated pyrite surface, which makes the pyrite surface further hydrophilic. Eventually, with the adsorption of water molecules, the adsorbed calcium (Ca) cation on the hydroxylated pyrite surface will complete its coordination shell surrounded by six ligand oxygens, which leads to the formation of a hydrophilic hydrated calcium film on the pyrite surface, thus achieving the hydrophilization of pyrite.
黄铁矿是一种在分选有价硫化物矿物和煤炭资源时令人困扰的脉石矿物，通常需要通过抑制剂使其表面亲水，以便在浮选过程中进行浮选。具体而言，通过使用廉价的石灰等抑制剂使黄铁矿表面亲水，从而实现黄铁矿的抑制。因此，本工作采用密度泛函理论（DFT）计算详细研究了高堿性石灰体系中黄铁矿表面的逐步亲水过程。计算结果表明，黄铁矿表面在高堿性石灰体系中易发生羥基化，黄铁矿表面的羥基化行为有利于热力学上单羥基钙物种的吸附。吸附在羥基化黄铁矿表面的单羥基钙可以进一步吸附水分子。同时，吸附的水分子之间以及与羥基化黄铁矿表面之间形成复杂的氢键网络结构，使黄铁矿表面进一步亲水。最终，随着水分子的吸附，吸附在羥基化黄铁矿表面的钙（Ca）阳离子将完成其被六个配体氧包围的配位壳，导致在黄铁矿表面形成亲水性水合钙膜，从而实现黄铁矿的亲水化。
