Froth flotation has been widely used in upgrading iron ores. Iron ore flotation can be performed in two technical routes: direct flotation of iron oxides and reverse flotation of gangue minerals with depression of iron oxides. Nowadays, reverse flotation is the most commonly used route in iron ore flotation. This review is focused on the reverse flotation of iron ores, consisting of reverse cationic flotation and reverse anionic flotation. It covers different types of collecting agents used in reverse iron ore flotation, the surface characteristics of minerals commonly present in iron ores (e.g., iron oxides, quartz, alumina-bearing minerals, phosphorus-bearing minerals, iron-bearing carbonates, and iron-bearing silicates), and the adsorption mechanisms of the collecting agents at the mineral surface. The implications of collecting agent–mineral interactions for improving iron ore flotation are discussed.

In mineral flotation, rheological problems have limited the efficient upgrading of low-grade and complex ores. Since pulp and froth rheology are deemed to play different roles in influencing the separation performance, in this paper, a brief review on pulp and froth rheology in flotation is provided, with an objective of developing a basic understanding of rheology in flotation. The essential variables that affect the rheology of a flotation pulp and froth are discussed. The methods for measuring pulp and froth rheology are presented. The correlations of pulp and froth rheological properties to flotation performance are reviewed. Strategies that are currently used to mitigate the deleterious effects of problematic ores in flotation are also provided for flotation optimization. Research gaps are also proposed to highlight the need of further exploration of flotation rheology in future.