Froth flotation is a process that is used in many industries for selectively separating hydrophobic and hydrophilic materials. Generally, the process works by passing air bubbles through an aqueous suspension of a “pulp” that contains the materials to be separated (e.g., target mineral particles and unwanted material). Through conditioning of the target mineral particles, it is possible to induce preferential attachment of the target mineral particles to the air bubbles. The air bubbles and attached mineral particles float to the surface of the aqueous suspension as “froth” (which may be subsequently removed), whereas the unwanted material does not float to the surface and becomes the “tailings” of the process.
In some cases, small molecules called “collectors” may be added to the pulp to selectively adsorb (e.g., through chemisorption or physisorption) onto the target mineral particles' surfaces and render the target mineral hydrophobic. Thus, a purpose of a collector is to selectively hydrophobize a target mineral so that the target mineral can attach to the air bubbles and float to the surface of the aqueous suspension. Collectors may be classified as nonionic, anionic, or cationic, and are typically selected based on the target mineral. For instance, if a sulfide mineral is the target mineral, then a sulfhydryl collector or a thiol collector might be selected (e.g., xanthates, dithiophosphates, dithiocarbamates). The efficacy of the separation achieved by the froth flotation process can therefore be significantly impacted by the selection of the collector.