Flotation Chemistry and Process Overview

Study Notes

Flotation is a process separating hydrophobic (water-repellent) particles from hydrophilic (water-wetted) particles using bubbles.
It's used in numerous industries, including wastewater treatment, mineral processing, and construction.
Over 100 minerals (copper, lead, zinc, nickel, silver, manganese, chrome, cobalt, titanium, quartz, feldspar, and coal) are enriched using flotation.
Flotation is a physicochemical process utilizing differences in mineral surface properties, dependent on wettability/hydrophobicity.
Several parameters impact flotation success, including shape factor and pH.

The process involves several stages: underground mining, open-pit mining, stockpiling, crushing, grinding, transfer to flotation plants, and flotation in cells.
Minerals that float easily are hydrophobic, while those that don't float are modified (using collectors) to become hydrophobic to float.
The medium for particle attachment to air bubbles must be continuous for effective flotation.
Various methods, including column flotation, the Jameson Cell, and the Microcel column, are employed in flotation.

Flotation reagents are chemicals added to the flotation medium to facilitate the process.
These reagents are categorized into collectors to attach minerals to bubbles, frothers to form and stabilize foam, activators that encourage reaction with desired minerals, depressants that hinder reactions with undesired minerals, pH regulators, and other supporting agents.

The buoyancy of the bubble must exceed gravity for efficient flotation.
Large contact angles aid mineral flotation.
Increasing the contact angle with collectors improves mineral-bubble attachment.
Ideally, the contact angle for effective flotation should be between 50° and 75°.

Minerals generally won't attach to bubbles if hydrophilic.
Hydrophobic traits are created or enhanced in minerals using specific chemicals called collectors so they can attach to bubbles.
Flotation reagents have polar and nonpolar groups.
Nonpolar groups (hydrocarbon chains) are hydrophobic, interacting poorly with water.
Polar groups are hydrophilic, strongly interacting with water.

Parameters such as ore mineralogical analysis, liberation degree, reagent selection, required reaction time, and pulp-solids ratio are essential for flotation experiments.
The Hallimond tube observes mineral behavior in dynamic environments.
Equipment like Denver flotation units and micro-flotation cells are used in laboratory trials.
Time-based variations in the amount of minerals attached to bubbles are tracked during experiments and correlated with varying collector concentrations and bubble sizes.
The amount of mineral attached to bubbles increases with decreasing bubble size.
Flotation recovery demonstrates a strong correlation with bubble-particle attachment time.
Analyzing minerals (e.g., Quartz), along with various collectors and different sizes of bubbles are relevant to successful flotation operations.