Froth flotation is a common mineral processing technique that is used to remove low economic gangue minerals, such as pyrite, from ore. The main hydrophilization mechanism on the pyrite surface is explained by the formation of hydrophilic iron (Fe) hydroxide and its complexation with calcium (Ca) and magnesium (Mg) ions; however, few quantitative results are available to determine the best physico-chemical condition to depress pyrite floatability. Fe-hydroxide formation, i.e., oxidative dissolution on a pyrite surface, is a kinetically control reaction; thus, this study investigated the short-term pyrite oxidation rate (~ 360 min) and the influence of the copresence of Ca and Mg under alkaline pH conditions (9, 10.5, and 12) as a fundamental study to establish optimal flotation and/or pre-treatment conditions for pyrite depression. The oxidative dissolution rates of pyrite increased after 120–150 min of reaction compared with the first reaction time: the rate constant (log k) increased from − 10.08 to − 9.5 in the absence of Ca and Mg. X-ray photoelectron spectroscopy analysis results showed that the formation of Fe_1−xS₂ became the dominant reaction in the first reaction stage; thereafter, S–S bond cleavage in the second reaction stage resulted in the acceleration of pyrite decomposition. Smaller rate constants resulted for the Ca and Mg solutions because of the formation of Ca and Mg hydroxides under alkaline conditions. However, this decrease in oxidation rate could influence the pyrite surface hydrophilization less, and hydrophilization has become the main reason for pyrite depression enhancement.

Graphical Abstract

中文翻译：

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碱性介质（pH 9-12）中黄铁矿初始氧化溶解的动力学研究以及钙和镁的影响：泡沫浮选中黄铁矿抑制的基础研究

泡沫浮选是一种常见的选矿技术，用于从矿石中去除低经济性脉石矿物，如黄铁矿。黄铁矿表面的主要亲水化机制可以通过亲水性氢氧化铁 (Fe) 的形成及其与钙 (Ca) 和镁 (Mg) 离子的络合来解释；然而，很少有定量结果可用于确定抑制黄铁矿可浮性的最佳物理化学条件。氢氧化铁的形成，即黄铁矿表面的氧化溶解，是一种动力学控制反应。因此，本研究调查了短期黄铁矿氧化速率（约 360 分钟）以及在碱性 pH 条件（9、10.5 和 12）下 Ca 和 Mg 共存的影响，作为建立最佳浮选和/或黄铁矿凹陷的预处理条件。k ) 在没有 Ca 和 Mg 的情况下从 - 10.08 增加到 - 9.5。X射线光电子能谱分析结果表明，Fe _{1− x} S ₂的形成成为第一反应阶段的主导反应；此后，第二反应阶段的 S-S 键断裂导致黄铁矿分解加速。由于在碱性条件下形成 Ca 和 Mg 氢氧化物，Ca 和 Mg 溶液的速率常数较小。然而，这种氧化速率的降低对黄铁矿表面亲水化的影响较小，亲水化已成为黄铁矿凹陷增强的主要原因。

图形概要