Collector
- Also known as
- collector reagent, flotation collector, xanthate
A collector is a flotation reagent that adsorbs onto the surface of a target mineral and makes it water-repellent, so that the mineral particles attach to air bubbles and float into the froth. Xanthates, dithiophosphates, fatty acids and amines are common collectors.
What is a collector?
In froth flotation, most mineral surfaces are naturally attracted to water, so they will not stick to air bubbles. A collector is the reagent that changes that for the mineral you want to recover. Collector molecules have a polar end that attaches to the mineral surface and a hydrocarbon end that points outward into the water. A particle coated this way becomes water-repellent, attaches to passing bubbles, and rises into the froth.
Collectors are the central reagent in any flotation scheme: the choice of collector largely determines which minerals float.
How collectors attach
Collectors bind to minerals in different ways, which is what makes them selective:
- Chemical adsorption, in which the collector reacts with metal atoms on the mineral surface. Sulfide collectors such as xanthates bind this way to copper, lead and zinc sulfides.
- Physical adsorption, driven by electrical attraction between a charged collector and an oppositely charged mineral surface. Amine and some fatty acid collectors act this way, which makes their performance sensitive to pH.
Main types of collectors
| Type | Examples | Typical targets |
|---|---|---|
| Thiol (sulfhydryl) collectors | Xanthates, dithiophosphates, thionocarbamates | Sulfide minerals of copper, lead, zinc and nickel; gold-bearing sulfides |
| Fatty acids and their salts | Oleic acid, tall oil fatty acids | Oxide minerals, phosphate, fluorite, and lithium minerals such as spodumene |
| Amines | Ether amines, fatty amines | Silicates, such as quartz in reverse flotation of iron ore; potash |
| Nonpolar oils | Fuel oil, kerosene | Naturally hydrophobic minerals such as coal and molybdenite |
Choosing and dosing a collector
A collector must be strong enough to float the target mineral, including fine and partly liberated particles, but selective enough to leave the gangue behind. Stronger, less selective collectors raise metallurgical recovery but tend to lower concentrate grade. Plants often use blends of collectors and adjust dosage stage by stage.
Collector performance depends on the whole reagent scheme: depressants prevent unwanted minerals from taking up collector, activators help some minerals accept it, and pH regulators control surface charge. Water chemistry, ore oxidation and slimes also affect how much collector reaches the target surface. Too much collector wastes reagent and can float unwanted minerals.
Collectors and Locus biosurfactants
Locus Mining develops biosurfactant-based flotation reagents that it describes as integrating with existing reagent programs to improve recovery and selectivity. Their role alongside collectors is established through laboratory and pilot testing on each ore.
Frequently asked questions
A collector makes the target mineral’s surface water-repellent so particles attach to bubbles. A frother acts mainly at the air-water surface, making bubbles smaller and the froth stable enough to carry the particles. Both are needed.
Xanthates are the most widely used collectors for sulfide ores. They are sulfur-containing compounds that bind chemically to sulfide mineral surfaces and make them water-repellent.
Because ore changes. Differences in mineralogy, grind size, oxidation and water chemistry alter how much collector the target mineral needs and how much is consumed by other surfaces.
Sources
- Wills' Mineral Processing Technology, 8th edition, B. A. Wills and J. A. Finch, Butterworth-Heinemann, 2016
- SME Mineral Processing and Extractive Metallurgy Handbook, Society for Mining, Metallurgy and Exploration, 2019