Date of Award


Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Chemical Engineering (PhD)

Administrative Home Department

Department of Chemical Engineering

Advisor 1

S. Komar Kawatra

Committee Member 1

Rebecca G. Ong

Committee Member 2

Tony N. Rogers

Committee Member 3



The reverse cationic flotation of hematite is the most common method to process hematite ores. The goal of this research is to understand the impact of fundamental water and surface effects to enable the optimization of the flotation process. At present, reverse cationic flotation is performed using a single chemical as both collector and frother. Excessive amounts of frother or collector should lead to diminished performance. This research investigates this phenomenon by replacing some of the collector with frothers. It was found that flotation recovery can be improved up to 2.5wt% via 10% replacement with methyl isobutyl carbinol (MIBC). Since most frothers are less expensive than the amine collector, there is a possibility of reducing cost of reagents and increasing profits in industry.

There is a large body of literature on the impact of calcium on the flotation process. However, despite magnesium and calcium often being treated as interchangeable in literature and practice, magnesium’s smaller atomic size suggests that its behavior in flotation should be stronger. This research investigates the effect of calcium and magnesium in the adsorption of starch onto the hematite. We have found that initially both ions are beneficial to the process but as the magnesium concentrations increase, it becomes detrimental to flotation. These results make it clear that magnesium is not a one-for-one replacement of calcium in iron ore flotation, and should be accounted for and, if necessary, controlled separately.

Lastly, the time it takes for the hematite to become fully hydrated may play a role in flotation. If the hydration of fresh surfaces takes place during the ½ to 2 hours that the xix hematite is expected to reside in the concentration process, then this could have a significant impact in flotation. In this research, the time scale of the hydration of pure hematite was determined to be on the order of 5 to 20 minutes, which tells us that in a plant-scale operation, it is very likely that the hematite is completely hydrated before it reaches flotation. These findings demonstrate improved understanding of reverse cationic flotation, which leads to a set of clear process recommendations.