Flotation reagents can be classified into multiple categories based on their functions, including frothers, collectors, adjusters (including activators, depressants, pH adjusters), and flocculants. Among these reagents, collectors play a central role, followed closely by depressants and frothers. So, how do these reagents interact with the slurry?
Through the diagram, the relationship between the three is manifested as follows: the frother is arranged at the gas-liquid interface, which promotes the generation of bubbles and maintains their stability by reducing the surface tension of the solution and other functions, thus facilitating mineralization; Depressants adsorb onto the surface of the suppressed mineral, enhancing its hydrophilicity and avoiding adhesion by bubbles; The hydrophilic mineral group of the collector interacts with the mineral, and its hydrophobic non-polar group faces outward, causing the mineral surface to become hydrophobic, which is then captured and floated by bubbles.
1. The hydrophobic behavior of reagents manifests in various forms
The mechanism of action of collectors on mineral surfaces involves the adsorption or reaction of affinity groups with mineral surfaces, mainly including the following:
(1) Physical adsorption. Its characteristics are low adsorption energy and small adsorption heat, mainly driven by van der Waals force or electrostatic force. There is no chemical bond formed between reagent molecules (or ions) and minerals, and there is no involvement in electron transfer or covalent bond formation, thus exhibiting non selective adsorption.
(2) Chemical adsorption. The characteristics of chemical adsorption are high adsorption energy, high adsorption heat, and the adsorption force comes from chemical bonds. It has selectivity, strong adsorption, and is not easy to desorb. As the temperature increases, the adsorption effect will be enhanced within a certain range.
(3) Surface chemical reactions. This is a further development of chemical adsorption, which triggers chemical reactions on mineral surfaces. The main difference between surface chemical reactions and chemical adsorption is that the reaction products form independent phases on the mineral surface.
2. Mineral structure and characteristics of flotation reagents
Based on the atomic structure of mineral elements, the electronic arrangement of ions, chemical affinity, and their mineralization characteristics, geochemistry divides mineral elements into the following three categories:
(1) Lithophilic elements: The electronic structure of these mineral metal cations is similar to that of inert gases, and they usually exist through physical adsorption. However, minerals formed from calcium and barium tend to undergo chemical adsorption.
(2) Copper friendly elements: These elements mainly constitute heavy non-ferrous metals and precious metal minerals, and their interaction with collectors is mainly manifested as chemical adsorption.
(3) Ferrophilic elements: mainly including transition metal elements, their reaction with collectors can be physical adsorption or chemical adsorption.
3.Classification of reagents
Based on the hydrophilicity of minerals and the role of reagents in the flotation process, reagents can be divided into sulfide ore reagents, sulfide ore oxide ore transition flotation reagents, oxide ore flotation reagents, and natural floatable mineral reagents. Please refer to the table below for detailed classification:
| Type | Bond type with mineral interactions | Typical minerals | Reagents |
| Sulfide ore | Covalent bond | Chalcopyrite, Sphalerite, Galena, etc | Xanthates, Dithiophosphates, IPETC |
| Sulfide Oxide transition ore | Covalent bonds, Ionic bonds | Hematite, Zircon, Cassiterite, Scheelite, Hematite | Hydroxamic acid |
| Oxidized ore | Ionic bond | Calcite, Barite, Fluorite | Oleic acid, Sulfonic acid |
| Natural floatable ore | Van der Waals force or hydrogen bonding | Graphite, Molybdenite, Sulfur, Talc | Kerosene, Coal tar |
In summary, the adsorption of reagents on mineral surfaces through the formation of covalent bonds has high selectivity, strong adsorption effect, and low hydrophilicity. In contrast, the adsorption selectivity generated by the formation of ionic bonds is poor, and due to the high polarity of the bonds, hydrophilicity is enhanced, while non-polar groups are usually larger. Therefore, non sulfide mineral reagents with high selectivity are relatively scarce, while those suitable for sulfide mineral flotation and with good selectivity are relatively easy to develop.
