Common mineral impurities in quartz sand, such as feldspar, mica, and other silicate minerals, are mostly separated by the silica sand flotation separation process. Based on the difference in the wettability of different mineral surfaces to water, hydrophobic particles tend to adhere to bubbles and float to the liquid surface, while hydrophilic particles will break off suspension or sink into the water after colliding with bubbles, thereby achieving extraction of silica sand.

The silica sand flotation separation process can not only remove mica and feldspar minerals but also floated minerals. Below, I will take you to learn more about how to realize the flotation separation of mica, feldspar, and apatite from silica sand.

1. Flotation separation of mica minerals and silica sand

Mica dissociates a large number of anions O2- and F- with extremely low zero electric points. After being exposed to the layered structure, they can be recovered with cationic collectors in a wide pH range (pH=2-13). The pH range of feldspar in the cation collection system (pH=4-11) is smaller than that of mica, so mica can preferentially float out under strong acid conditions.

2. Flotation separation of feldspar minerals and quartz sand

Feldspar and quartz sand are both framework silicate minerals. In addition to having similar physical properties, chemical composition, and structure, they also have the same charge mechanism in an aqueous solution and have very low zero electric points. The main difference between feldspar and quartz sand lies in the structure of feldspar. Al-oxy tetrahedron replaces silicon-oxy tetrahedron, and alkali metal ions such as K+ and Na+ are introduced as electricity price compensation. Alkali metal ions are easily dissociated in water, making the zero electric point of feldspar lower than that of quartz sand, thus realizing the silica sand flotation separation process.

3. Flotation separation of apatite minerals and silica sand

Phosphate minerals in quartz sand generally exist in the form of apatite. The surface dissolution of apatite in the flotation slurry will change the surface properties of the mineral and the chemical environment of the flotation slurry. Generally, quartz sand is easily activated by Ca2+ under alkaline conditions (pH greater than 10), so the dissolved Ca2+ in the apatite solution will adversely affect the separation of apatite and quartz sand. Since the floatability of apatite is better than quartz, Na2CO3 can be used as a pH adjuster to improve the floatability of apatite and increase the difference in floatability between apatite and quartz sand. Therefore, when flotation and separation of apatite and quartz sand are carried out under alkaline conditions, it is recommended to choose Na2CO3 as the pH regulator and water glass as the inhibitor.

In the actual beneficiation process, the selection of the silica sand flotation separation process is often determined by various factors such as the nature of the quartz sand ore, the processing plant conditions, and the investment budget. It is recommended that when making a selection, you should first understand the silica sand and stone itself, and select the process flow in a targeted manner through the beneficiation test report to strive for the ideal technical and economic benefits.