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砷是重选和浮选贱金属精矿中的有害元素,在选矿中应该尽力降低其在精矿中的含量,为冶炼提供合格物料。在一些澳大利亚锡和钽的选矿回路中,砷以单质砷、斜方砷铁矿或者毒砂的形式存在。对毒砂浮选的研究比较多,但是对斜方砷铁矿和单质砷的浮选知之甚少。本文主要研究以乙基黄药为捕收剂时,矿浆pH和矿浆电位(Eh)对金属砷可浮性的影响。试验中使用人工合成的金属砷和石英的混合物。在pH5～10范围,金属砷的可浮性较好(使用Aerofroth 65起泡剂和40g/tKEX,8min浮选回收率接近95%),进一步增大pH,回收率缓慢降低。在pH6时,砷金属在矿浆电位+125～+275mV范围内,可浮性较好,但是出现上临界电位+375mV。在较强的还原性条件下(低于+125mV),其回收率缓慢降低。此时浮选速度较慢。在pH10时,砷金属在电位为-300～+225mV范围内,可浮性较好,有趣的是,在所观察的还原性电位范围内(低至-300mV),没有观察到下临界电位。浮选速率数据表明,矿浆电位低于+225mV时,浮选速度较快。在pH6和在没有捕收剂存在时,金属砷不可浮,这表明金属砷与其他金属一样没有天然可浮性。重要的是,本研究结果表明,可以在较宽的pH范围内,通过控制浮选电位和使用简单的药剂组合就可脱除贱金属精矿中的金属砷。
Arsenic is a harmful element in the re-election and flotation of base metal concentrates. In mineral processing, it should try to reduce its content in the concentrate and provide qualified materials for smelting. In some Australian tin and tantalum beneficiation circuits, arsenic is present as elemental arsenic, orthopyroxene or arsenopyrite. There are many studies on the flotation of arsenopyrite, but little is known about the flotation of orthopyroxene and elemental arsenic. In this paper, the effects of pulp pH and pulp potential (Eh) on arsenic buoyancy were studied with ethyl xanthate as a collector. The experiment used a mixture of synthetic arsenic and quartz. In the range of pH5 ~ 10, the floatability of metal arsenic is better (using Aerofroth 65 foaming agent and 40g / tKEX, the recovery of flotation is close to 95% in 8min), the pH is further increased and the recovery rate is slowly decreased. At pH 6, the arsenic metal floatability is good in the range of + 125 ~ + 275mV, but the upper critical potential is + 375mV. In the strong reducing conditions (less than +125 mV), the recovery rate decreased slowly. Flotation at this time slower. At pH 10, the arsenic metal has a good floatability at potentials of -300 to +225 mV, and it is interesting that no lower critical potential is observed in the observed reduction potential range (down to -300 mV). Flotation rate data show that when the slurry potential is lower than +225 mV, the flotation speed is faster. Metallic arsenic does not float at pH 6 and in the absence of collector, indicating that metal arsenic, like other metals, has no natural buoyancy. Importantly, the results of this study show that metallic arsenic in base metal concentrates can be removed over a wide pH range by controlling the flotation potential and using a simple combination of agents.