Electroflotation is a clean technique potentially able to recover fine particles from mineral suspensions. The aim of the present work was to evaluate the electroflotation of fines and ultrafine particles of an itabiritic iron ore using a biosurfactant extracted from Rhodococcus opacus bacteria. Infrared spectroscopy and zeta potential measurements confirmed the interaction between the biosurfactant and the mineral surface. The isoelectric point of hematite presented a value of about pH 5.3; after interacting with the biosurfactant, a charge reversal point of pH 3.5 was observed. The biosurfactant reduced the air/water surface tension from 71 to 40 mN/m, using 25 mg/L concentration. The electroflotation process of fine and ultrafine particles was evaluated as a function of pH, biosurfactant concentration, stirring of the aqueous suspension and current density. It was observed that the iron recovery (%) and iron grade (%) were negatively affected by increasing pH value. Therefore, best results were achieved at pH 3. Biosurfactant concentration and current density positively affected both response variables. An iron recovery value of about 83% and an iron grade of about 59% were achieved for the −38 + 20 µm size fraction; whereas, higher values were attained (98% and 64%, respectively) for the finer size fraction −20 µm.

中文翻译：

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使用生物表面活性剂电浮选从铁矿石细粒中回收赤铁矿的方法

电浮选是一种清洁的技术，有可能从矿物悬浮液中回收细颗粒。本工作的目的是使用从不透明红球菌中提取的生物表面活性剂来评估伊塔比利铁矿的细粉和超细颗粒的电浮选。菌。红外光谱和ζ电势测量证实了生物表面活性剂与矿物表面之间的相互作用。赤铁矿的等电点的pH值约为5.3；与生物表面活性剂相互作用后，观察到pH 3.5的电荷反转点。生物表面活性剂使用25 mg / L的浓度将空气/水表面张力从71降低到40 mN / m。根据pH，生物表面活性剂浓度，水悬浮液的搅拌和电流密度，对细颗粒和超细颗粒的电浮过程进行了评估。观察到铁的回收率（％）和铁的品位（％）受到pH值升高的负面影响。因此，在pH 3时可获得最佳结果。生物表面活性剂的浓度和电流密度对两个响应变量均产生积极影响。对于-38 + 20 µm尺寸级分，铁的回收率约为83％，铁的品位约为59％。而对于-20 µm的细小颗粒，则可获得更高的值（分别为98％和64％）。