Coordination reaction triggered xanthan gum and Fe(III) self-assembly and adsorption on hematite surface for quartz-hematite flotation separation

The cation reverse flotation is a widely used method in improving the grade of iron ore concentrate, but hematite depressant is the key. In this work, the flotation behavior of hematite and quartz using the complex of Fe(III) and xanthan gum (Fe(III)-XG) as depressant was investigated via micro-flotation tests. The results show that Fe(III)XG showed excellent separation efficiency for hematite from quartz using dodecylamine (DDA) as collector. The adsorption capacity and water contact angle analysis indicate that the adsorption of Fe(III)-XG onto hematite hinders the adsorption of DDA onto hematite surface, and the adsorption quantity of Fe(III)-XG on quartz surface is lower than on hematite surface. Further, XRD, FTIR and XPS analyses were performed to detect the functional part and adsorption mechanism of Fe(III)-XG. The results indicate that the coordination of Fe(III) with -COOH and -OH in xanthan gum (XG) could form Fe(III)-XG complex which is beneficial to adsorption onto mineral surface selectively. The weak adsorption of Fe(III)-XG onto quartz surface by sites of Si-OH could not hinder the electrostatic adsorption of positively charged DDA while the pre-adsorption of Fe(III)-XG on the hematite surface through selective chemical action hinders the adsorption of DDA. The model of flotation separation of hematite from quartz system with Fe(III)-XG and DDA was drawn.