Flotation Chemistry and Process Overview

Flotation Chemistry

• Flotation is a process for separating hydrophobic (water-repellent) particles from hydrophilic (water-wetted) ones using bubbles.
• It's used in various industries, including wastewater treatment, mineral processing, and construction.
• At least 100 different minerals (like copper, lead, zinc, nickel, silver, manganese, chrome, cobalt, titanium, quartz, feldspar, and coal) are enriched through flotation.

Flotation Process

• The process involves several stages, including underground mining, open-pit mining, stock area, crushing, transfer to grinding, grinding at the flotation plant, and flotation in cells.
• Minerals are separated based on their wettability: hydrophobic minerals attach to air bubbles while hydrophilic minerals sink.
• The continuous process of flotation involves proper grinding of the ore, ensuring continuous froth, adding frothers to the medium, and adding flotation reagents to ensure bubble capture of mineral particles.
• The medium must remain continuous for mineral particles to properly attach to air bubbles.

Flotation Introduction

• Flotation is a physico-chemical process leveraging differences in mineral surface properties (wettability or hydrophobicity).
• Key parameters affecting flotation success include shape factor, pH, and surface roughness of the minerals, along with the size of the air bubbles.

Flotation Reagents

• Flotation reagents are grouped into collectors, frothers, and control reagents (which include activators and depressants, pH regulators, and others).
• Collectors attach minerals to air bubbles.
• Frothers create and stabilize foam.
• Activators facilitate desired mineral reactions.
• Depressants prevent unwanted mineral reactions.
• pH regulators control the pH of the environment.

Flotation Chemistry

• Minerals typically don't attach to bubbles if they're hydrophilic.
• Mineral enrichment through flotation depends on making mineral surfaces hydrophobic, the pH of the environment, and air bubble size.
• The chemicals added to the flotation medium are called flotation reagents.

The Main Rules of Operation

• Key operational factors for effective flotation include bubble-particle attachment efficiency and the number of bubbles.

Flotation Reagents (Continued)

• Activators and depressants facilitate and disrupt reactions, respectively, between desired minerals and reagents.
• Dispensers prevent mineral particles from sticking together in the pulp.

Flotation Technique

• Prior to flotation, ore mineralogical analysis, liberation degree, appropriate reagents, required time for reagent adsorption, and pulp-solids ratio are determined.

Hallimond Tube

• A micro-flotation unit (made of glass) used to study mineral behavior in a dynamic environment.

Micro-flotation Cell Experiments

• Details of micro-flotation cell experimental setups are provided.

Denver Flotation Experiments

• Denver flotation is a common laboratory procedure for mineral processing trials.
• Specific experimental procedures include conditioning the mineral samples within the flotation device and introducing air.
• Collected concentrates are sampled and tested at different time intervals (0–1 min., 1–2 min., 2–4 min., 4–8 min., and 8–16 min.).
• Float and sink product samples are dried and weighed for final analysis.

Pilot-Scale Flotation Experiments

• Includes various pilot-scale flotation equipment setups, including circuits, to study treatment processes for different materials.

Flotation Kinetics

• Provides correlations between attachment time, minerals, and flotation grade.

Next Week

• Scheduled lessons include coagulation/flocculation, rheology, summary, and lab compensations.

Results for Bubble-Particle Attachment, Time Experiments

• The number of particles attached to the bubble's surface increases with increasing SDS concentration
• Measurements of bubble-particle attachment time and the relationship between attachment time and flotation recovery. The amount of particles attached to the bubble surface increases as the bubble size decreases.

Mineral Commodities

• A supplementary list of common minerals, including oxides, silicates, sulfides, complex hydrocarbons, and some soluble salts

Flotation Parameters

• The buoyancy of the bubble must exceed the gravity force of the mineral for successful flotation.
• A large contact angle makes minerals float more easily.
• The contact angle is a measure of a mineral's suitability for flotation.
• A good flotation involves a contact angle between 50° and 75°.

Flotation Reagents (Polar and Nonpolar Groups)

• Reagents for flotation include both polar and nonpolar groups.
• Nonpolar groups (hydrocarbon chains) are hydrophobic because they interact weakly with water molecules.
• Polar groups are hydrophilic, strongly interacting with water molecules.

Adsorption of Collectors on Mineral Surfaces

• There are different types of adsorption (physical and chemical) of collectors on a mineral surface
• The adsorption depends on the charge of the mineral surface

Batch Scale Flotation Experiments

• The chemical analysis of water used in the process is included
• Results from a batch scale experiment with different flotation concentrates.