Activation effect of Pb2+ in cassiterite flotation with styrene phosphonic acid as collector
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摘要: 通過單礦物浮選試驗揭示了Pb2+對苯乙烯膦酸(SPA)浮選錫石效果的影響規律,在此基礎上,利用接觸角測定、Zeta電位檢測、紅外光譜分析和浮選溶液化學研究了苯乙烯膦酸浮選錫石體系中Pb2+的活化作用機理.單礦物試驗結果表明:在礦漿pH為2.0~8.0的區間內Pb2+對錫石的浮選具有明顯的活化作用,礦漿pH為4.0時錫石的回收率最高,達到93.78%,與不存在Pb2+的情況相比提高了5.33%.Zeta電位檢測、紅外光譜分析和浮選溶液化學結果表明:苯乙烯膦酸主要化學吸附于錫石表面,使錫石表面的Zeta電位負移,Pb2+的作用促進了苯乙烯膦酸的吸附,進一步降低了錫石表面的Zeta電位;Pb2+可以與錫石表面的Sn4+發生置換,PbOH+能夠與錫石表面的Sn-OH發生相互作用形成以Sn-O-Pb+形式存在的絡合物,這些作用增加了錫石表面的活性位點數量,使得苯乙烯膦酸在錫石表面的吸附量增多,導致了錫石的活化.Abstract: Metal ions have a very important influence on the flotation process of minerals, and some of them can activate minerals and thus yield an improvement in the flotation effect. Some production practices have shown that Pb2+ has an activation effect in the process of cassiterite flotation, which can improve the rate of cassiterite recovery. Styrene phosphonic acid is the most commonly used collector in the production of cassiterite flotation. In this study, the activation effect of Pb2+ in cassiterite flotation when styrene phosphonic acid is used as a collector is revealed by single mineral flotation tests. The activation mechanism of Pb2+ in the process of styrene phosphonic acid collecting cassiterite is assessed by contact angle measurement, zeta potential determination, IR spectroscopy, and solution chemistry analysis. The results of single mineral flotation tests indicate that Pb2+ can increase the floatability of cassiterite when the pH is 2.0~8.0, and at a pH of 4.0, the recovery rate of cassiterite reaches maximum, 93.78%, which is 5.33% higher than the recovery rate without Pb2+. The results of zeta potential determination, IR spectroscopy, and solution chemistry analysis show that the styrene phosphonic acid can be adsorbed on the cassiterite surface in form of chemical adsorption, causing the zeta potential of the surface to shift toward the negative direction, and the Pb2+ can promote the adsorption of styrene phosphonic acid on the cassiterite surface, making the zeta potential of the surface lower. Moreover, the Sn4+ on the cassiterite surface can be replaced with Pb2+ and the hydrolyzed species PbOH+ in solutions can interact with Sn-OH on the surface to form the surface complex Sn-O-Pb+, which may lead to an increase in the number of active sites on the cassiterite surface, promoting the adsorption of styrene phosphonic acid on the cassiterite surface and resulting in the activation of cassiterite.
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Key words:
- cassiterite /
- styrene phosphonic acid /
- Pb2+ /
- flotation /
- activation mechanism
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表 1 錫石試樣化學成分分析結果(質量分數)
Table 1. Chemical composition of cassiterite sample?
% SnO2 Na CaO MgO K2O Al2O3 SiO2 96.31 < 0.01 < 0.01 0.25 < 0.01 1.49 0.086 表 2 試驗所用藥劑
Table 2. List of reagents used in experiments
藥劑名稱 分子式 純度 生產廠家 苯乙烯膦酸 C8H9O3P 分析純 北京礦冶研究總院 硝酸鉛 Pb(NO3)2 分析純 國藥集團化學試劑有限公司 鹽酸 HCl 分析純 北京化學試劑公司 氫氧化鈉 NaOH 分析純 北京市紅星化工廠 表 3 不同藥劑作用后錫石表面接觸角的變化
Table 3. Changes of cassiterite surface contact angle in the presence of different reagents
藥劑名稱 接觸角,θ/(°) cosθ 1-cosθ — 33 0.84 0.16 苯乙烯膦酸 124 -0.56 1.56 Pb2++苯乙烯膦酸 133 -0.68 1.68 -
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