Department of Metallurgical Engineering, College of Mines and Earth Sciences, University of Utah, 135 S 1460 E, Room 412, Salt Lake City, UT 84112-0114, USA.
J Colloid Interface Sci. 2018 Aug 15;524:337-349. doi: 10.1016/j.jcis.2018.04.002. Epub 2018 Apr 3.
The function of corn starch and the significance of the order of addition of corn starch and mono ether amine in the reverse flotation of iron ore has been investigated. Understanding hematite depression with starch and the corresponding hydrophilic state involves consideration of adsorption with amine as well as flocculation of fine hematite. Captive bubble contact angle and micro-flotation experiments indicated that amine has an affinity towards both hematite and quartz, and that the role of starch is to hinder the adsorption of amine at the hematite surface so that flotation is inhibited. Micro-flotation results confirmed that quartz does not have affinity towards starch at pH 10.5. In addition to competitive adsorption, flocculation of fine hematite occurs and images from high resolution X-ray computed tomography (HRXCT) and cryo-SEM reveal further detail regarding floc structure. These results provide substantial evidence that the fine hematite particles are flocculated in the presence of corn starch, and flocculation is dependent on the particle size of hematite, with greater flocculation for finer particles. Thus, starch is playing a dual role in the reverse flotation of iron ore, acting as a depressant by hindering amine adsorption at the hematite surface in order to maintain the hydrophilic surface state of hematite, and acting as a flocculant to aggregate fine hematite particles, which if not flocculated, could diminish the flotation separation efficiency by being transported to the froth phase during reverse flotation.
研究了玉米淀粉的作用以及玉米淀粉和单醚胺在铁矿石反浮选过程中的添加顺序的意义。理解淀粉对赤铁矿的抑制作用以及相应的亲水状态需要考虑胺的吸附以及细粒赤铁矿的絮凝。束缚气泡接触角和微浮选实验表明，胺对赤铁矿和石英都有亲和力，淀粉的作用是阻止胺在赤铁矿表面的吸附，从而抑制浮选。微浮选结果证实，在 pH 值为 10.5 时，石英对淀粉没有亲和力。除了竞争性吸附外，细粒赤铁矿还会发生絮凝，高分辨率 X 射线计算机断层扫描（HRXCT）和冷冻扫描电镜（cryo-SEM）的图像进一步揭示了絮体结构的细节。这些结果提供了充分的证据表明，在玉米淀粉存在的情况下，细粒赤铁矿发生絮凝，絮凝作用取决于赤铁矿的粒径，粒径越小，絮凝作用越明显。因此，淀粉在铁矿石反浮选过程中发挥了双重作用，一方面通过阻止胺在赤铁矿表面的吸附来抑制赤铁矿的亲水表面状态，另一方面作为絮凝剂聚集细粒赤铁矿颗粒，如果不絮凝，在反浮选过程中可能会被运送到泡沫相中，从而降低浮选分离效率。
