草酸/超声预处理对氧化黄铁矿浮选的影响

Effect of Oxalic Acid/Ultrasonic Pretreatment on the Flotation of Oxidized Pyrite

黄铁矿表面严重氧化后会形成稳定性较高的氧化层,严重影响浮选药剂的吸附,使得矿物浮选回收难度增加。为实现严重氧化后黄铁矿的有效浮选回收,研究了草酸和超声预处理对严重氧化后黄铁矿可浮性和表面铜离子吸附活化的影响。单矿物实验结果表明,经草酸预处理后黄铁矿浮选效果不理想,即使在草酸用量达到2.5 g/L时,黄铁矿的回收率仍仅有44.68%,并且添加铜离子后,黄铁矿回收率仅增加至48.13%;而经超声预处理后黄铁矿回收率明显增加,在超声功率为100 W时,黄铁矿的回收率达到了79.72%,且在超声时间为2 min、超声功率为60 W时添加铜离子活化,黄铁矿回收率可达到84.77%。由此可见,添加铜离子后可在超声功率较低时实现黄铁矿的有效浮选回收。主要原因是采用草酸预处理的方式,黄铁矿表面氧化组分脱落程度较低,而经超声预处理后,大量亲水性铁的氧化物/氢氧化物、硫酸盐从表面脱落,增加了表面铜离子吸附位点,进而促进了捕收剂在黄铁矿表面的吸附。

A highly stable oxidation layer is formed on the surface of pyrite after heavy oxidation,which significantly affects the adsorption of flotation reagents and increase the difficulty of the flotation recovery of pyrite.In order to realize the effective flotation recovery of heavily oxidized pyrite,the effect of oxalic acid and ultrasonic pretreatment on the floatability of heavily oxidized pyrite and the adsorption of copper ions on surface was investigated.The results of microflotation experiments showed that the flotation of pyrite after treated by oxalic acid pretreatment was not ideal.Even when the dosage of oxalic acid reached 2.5 g/L,the recovery of pyrite was still only 44.68%.After adding copper ions,the recovery of pyrite only increased to 48.13%.However,the recovery of pyrite significantly increased after treated with ultrasonic pretreatment.The recovery reached 79.72%when the ultrasonic power was 100 W.After adding copper ions,the recovery reached 84.77%when the ultrasonic power and time was 60 W and 2 min,respectively.This indicated that pyrite could be effectively recovered at low ultrasonic power after adding copper ions.The main reason was that the shedding degree of oxidized species on pyrite surface was low after treated by oxalic acid pretreatment.However,large amounts of hydrophilic iron oxides/hydroxides and sulfates was detached from the surface after treated by ultrasonic pretreatment,thus increasing the active sites for the adsorption of copper ions and promoting the adsorption of collectors on the surface of pyrite.