Utilization of humic acid as a depressant for hematite in the reverse flotation of iron ore

In the present work the utilization of humic acid as a depressant for hematite in the iron ore flotation process was studied taking into consideration its physicochemical properties. Contact angle measurements of hematite and quartz were performed using a computer controlled Ramé-Hart goniometer. After conditioning with humic acid at pH 10.2, at low dodecylamine concentrations, hematite presented a much lower contact angle as compared to that of quartz under the same conditions.Microflotation tests were carried out using an EMDEE flotation apparatus. Initially, the two minerals were studied individually. The results showed that, depending of the humic acid and dodecylamine concentrations, the floatability of quartz was higher than 90% and 61% of the hematite was depressed. The flotation of the mixture of the two minerals (25% quartz and 75% hematite) was subsequently studied. The hematite recovery was higher than 90% in the depressed concentrate which assayed 86.0% Fe2O3. The results suggest that humic acid could be used as an alternative for starch in the iron ore flotation process.