锡石表面铜、铅活化及黄药吸附作用的研究：DFT计算

浮选是微细粒锡石选矿中最重要的方法,其中脱硫是选锡之前的关键作业。对于脱硫过程中所引入的Cu²⁺和丁基黄药(BX),在脱硫阶段会造成锡石的损失,而在后续浮选中残余的丁基黄药会与Pb²⁺发生协同作用捕收少量锡石。本文采用密度泛函理论(DFT)研究了Pb²⁺和Cu²⁺在锡石的活化机理,以及丁基黄药在锡石表面的吸附。DFT计算结果表明,Cu²⁺、Pb²⁺均能活化锡石,且两种离子的活化机理存在显著性差异。而丁基黄药也对Cu²⁺、Pb²⁺活化后的锡石具有捕收作用,其Pb²⁺活化后的吸附能为-264.3kJ/mol,Cu²⁺活化后的吸附能为-125.5kJ/mol,Pb²⁺活化作用更强,该现象与工业现状一致。Mulliken布居显示,在Pb²⁺活化下,丁基黄药的两个S原子与Pb形成稳定螯合结构,在Cu²⁺活化下,丁基黄药的双键S2原子与Cu形成Cu-S键。

Activation of Copper and lead and xanthate adsorption on cassiterite surface: DFT calculation

Flotation is essential for fine-grained cassiterite, and desulfurization is the critical operation before this work. The Cu²⁺ and butyl xanthate (BX) introduced in the desulfurization process will cause the loss of cassiterite at this stage; the residual BX in the subsequent flotation will act synergistically with Pb²⁺ to capture a small amount of cassiterite. In this paper, density functional theory (DFT) was used to study the activation mechanism of Pb²⁺ and Cu²⁺ on cassiterite, which was compared with the adsorption of BX on the cassiterite surface. DFT calculation results show that both Cu²⁺ and Pb²⁺ can activate cassiterite, and the activation mechanisms of the two ions are significantly different. BX can capture the cassiterite activated by Cu²⁺ and Pb²⁺; the adsorption energy of Pb²⁺ activation is -264.3kJ/mol, and the adsorption energy of Cu²⁺ activation is -125.5kJ/mol. The activation of Pb²⁺ is stronger, consistent with the industry"s current state. Mulliken population shows that the two S atoms of BX form a stable chelate structure with Pb under the activation of Pb²⁺, while the double bond S2 atom of BX forms a Cu-S bond with Cu under the activation of Cu²⁺.