Physicochemical aspects of anionic flotation in the hematite/dolomite/quartz system

Flotation of carbonate-bearing iron ores remains a technical challenge due to the complexities of their physicochemical behavior. This study aims to characterize the electrokinetic and aggregation properties in these ores and relate them to their flotation response. Electrophoresis tests used two supporting electrolytes, KCl and NaNO3. NaNO3 exhibited specific adsorption onto hematite but was indifferent toward dolomite and quartz, suggesting weaker interactions between the surface sites of the latter minerals and the added ions. The electrokinetic potential correlated strongly with the dispersion behavior of the minerals. With sodium octadecenoate at the isoelectric point, significant aggregation occurred among the mineral particles. Microflotation in a Hallimond tube indicated a selectivity window between pH 7 and pH 9, in the absence of a depressant when using isolated minerals. The campaign was successful, achieving a metallurgical recovery of 94.7 %, Gaudin selectivity index of 23.5 and hematite content of 98.4 % in the concentrate (with corresponding quartz content of 1.65 %).