Three Core Flotation Reagents and Their Mechanisms

Flotation reagents are mainly divided into three categories: collectors, frothers and modifiers.

Collector: Imparts hydrophobicity to minerals so that particles can attach to bubbles

Most natural mineral surfaces are hydrophilic and hardly bind to bubbles in pulp. The core function of a collector is to selectively adsorb onto the target mineral and form a hydrophobic surface layer. One end of the reagent bonds to the mineral surface, while the outward hydrophobic hydrocarbon chain switches the mineral surface from hydrophilic to hydrophobic, allowing mineral particles to adhere to bubbles and rise with the froth.

For iron ore reverse flotation, there are two mainstream collectors:

• Anionic collectors: Represented by fatty acid soaps such as oleic acid and RA-935. They adsorb onto activated quartz surfaces via carboxyl groups, mostly applied in heated flotation. They feature strong collecting capacity yet relatively poor selectivity.
• Cationic collectors: Dodecylamine and ether amine are typical examples. They can collect quartz under neutral pulp conditions without heating, supporting a simple reagent regime. Their downside is high sensitivity to slime and sticky froth.

Frother: Generates stable fine bubbles to act as flotation carriers

Hydrophobic particles alone cannot achieve separation. Large air bubbles injected into the pulp tend to rupture during upward movement and fail to carry mineral particles. As surface-active agents, frothers arrange themselves at the gas-liquid interface. They break large bubbles into numerous fine, uniform microbubbles and thicken the hydration film on bubble surfaces to prevent coalescence and premature bursting.

Common frothers include pine oil, MIBC and isooctanol. Frothers do not collect minerals directly, yet they govern bubble quantity, size and stability, which determine the collision and attachment efficiency between particles and bubbles. Poor froth quality will severely weaken the performance of collectors.

Modifier: Control hub of the flotation system to improve separation selectivity

Modifiers cover a wide range of chemicals and are critical to flotation technology. Almost all reagents other than collectors and frothers fall into this group. Their core purpose is to adjust pulp conditions and enhance separation selectivity. Three widely used modifiers for iron ore reverse flotation are listed below:

• Depressants: Starch and carboxymethyl cellulose (CMC) are commonly used. They selectively adsorb onto iron mineral surfaces and render them hydrophilic, preventing iron minerals from floating together with gangue minerals. They are essential for guaranteeing concentrate grade.
• Activators: Lime is the typical activator. It loads calcium ions on quartz surfaces to create adsorption sites for anionic collectors. Without activation, many collectors cannot function properly.
• pH regulators: Sodium hydroxide and sulfuric acid are used to adjust pulp acidity/alkalinity to the optimal pH range for reagents. For instance, anionic reverse flotation generally requires a strongly alkaline environment. Deviation from the target pH will greatly reduce reagent adsorption efficiency.