Reverse cationic flotation is the most known beneficiation method for the separation of fine hematite particles from silicates. In this process, the depression of the hematite surface is an essential factor. Thus, the development of environmentally friendly depressants plays a critical role. Tannin (TA) as a natural and eco-friendly organic reagent has not yet been considered for such a purpose. Through the reverse cationic flotation, the depression effect of TA was investigated by single and mixture of minerals. Micro-flotation tests and wettability analysis based on contact angle measurements by the captive bubble method (CBM) were conducted. The surface adsorption mechanism of TA on the hematite and quartz was explored through turbidity, zeta-potential measurements, surface adsorption tests, and Fourier transform infrared (FT-IR) analyses. The micro-flotation results indicated that TA could selectively depress more than 90% of hematite, while its effect on quartz floatability was negligible (<8% depressing). Surface wettability analysis demonstrated that TA in the presence of 30 mg/L collector could significantly increase the work of adhesion of hematite from 135.5 to 143.1 erg/cm², whereas it increased the work of adhesion of quartz from 117.1 to 120.7 erg/cm². Surface adsorption analysis depicted that in the presence of 100 mg/L TA, the adsorption amount of TA on the hematite surface was 0.99 mg/g, while this amount for quartz was 0.17 mg/g (around 6 times lower than hematite). Turbidity measurements, applied to clarify the aggregation – dispersion behavior of pure minerals in the TA presence, showed that TA had a dispersion effect on the quartz particles, whereas TA caused hematite aggregation. Surface analyses proved that TA selective adsorption occurred on the hematite surface mainly by chemisorption. In contrast, poor physical adsorption was the main interaction between TA and the quartz surface.

反向阳离子浮选是从硅酸盐中分离赤铁矿细颗粒的最著名的选矿方法。在此过程中，赤铁矿表面的凹陷是必不可少的因素。因此，开发环境友好的抑制剂起着至关重要的作用。单宁（TA）作为天然和环保的有机物 尚未考虑将试剂用于此目的。通过反向阳离子浮选，通过单一矿物和混合矿物研究了TA的抑制作用。进行了基于浮选气泡法（CBM）的接触角测量的微浮选试验和润湿性分析。通过浊度，ζ电势测量，表面吸附测试和傅立叶变换红外（FT-IR）分析，探索了TA在赤铁矿和石英上的表面吸附机理。微浮选结果表明，TA可以选择性地压制90％以上的赤铁矿，而对石英浮性的影响可以忽略不计（压下<8％）。表面润湿性分析表明，在存在30 mg / L捕收剂的情况下，TA可以将赤铁矿的粘附功从135.5显着增加到143。²，而它增加了石英的粘附功从117.1到120.7 erg / cm ²。表面吸附分析表明，在存在100 mg / L TA的情况下，赤铁矿表面TA的吸附量为0.99 mg / g，而石英的吸附量为0.17 mg / g（比赤铁矿低约6倍）。浊度测量用于澄清聚集-在TA存在下纯矿物的分散行为表明，TA对石英颗粒具有分散作用，而TA导致赤铁矿聚集。表面分析表明，TA选择性吸附主要通过化学吸附作用发生在赤铁矿表面。相反，不良的物理吸附是TA与石英表面之间的主要相互作用。