Inorganic Salt Ions: Enhancing Flake Graphite Flotation Efficiency

Graphite, a key raw material in new energy, aerospace, and other high-tech fields, has increasingly stringent purity requirements. However, natural graphite ores often contain impurities like quartz and mica, posing challenges to flotation—the most effective enrichment method—such as low recovery rates and high reagent consumption. In recent years, the application of inorganic salt ions in graphite flotation has opened a new path for efficient purification, achieving breakthroughs in both technical indicators and economic benefits.

The "Hidden Power" of Inorganic Salt Ions in Flotation

Traditional graphite flotation relies on collectors like kerosene and frothers such as 2# oil, but it struggles with insufficient recovery of fine flake graphite and excessive reagent usage. Studies have shown that inorganic salt ions (K⁺, Mg²⁺, Al³⁺) can significantly enhance flotation: at a concentration of 0.09mol/L, the recovery rates of graphite in KCl, MgCl₂, and AlCl₃ solutions reach 84.54%, 94.82%, and 95.89% respectively, with the strengthening effect following the order Al³⁺ > Mg²⁺ > K⁺.

In practical ore tests, adding MgCl₂ to the open-circuit process involving five regrindings and six cleanings increased the fixed carbon content of the final concentrate by 1.80% and the recovery rate by 8.85%, reaching 94.77% and 69.71% respectively. This not only reduces the consumption of kerosene and 2# oil but also shortens flotation time, demonstrating significant advantages in energy conservation and emission reduction.

The Mechanism Behind the Enhancement

The effectiveness of inorganic salt ions stems from their dual regulation of graphite surface properties and the solution environment:

Enhancing hydrophobicity: Inorganic salt cations compress the electric double layer between graphite particles and bubbles, reduce the absolute value of the zeta potential on the graphite surface, and decrease surface hydration. For instance, the contact angle of graphite in a 0.2mol/L AlCl₃ solution increases from 50.5° (in deionized water) to 59.5°, markedly boosting hydrophobicity.

Stabilizing foam: The hydration of inorganic salt ions and differences in ion migration rates generate numerous stable small bubbles (with diameters of 0.1-0.3mm). The foam half-life of AlCl₃ solution reaches 8s, far exceeding that of pure water, increasing the collision probability between graphite particles and bubbles.

Broad Prospects for Industrial Application

The use of inorganic salt ions not only improves graphite flotation efficiency but also offers a new approach to water-saving production—using salt-containing water (e.g., mine water, seawater) instead of freshwater for flotation, which is highly significant for water-scarce mining areas. With ongoing optimization of reagent systems and process parameters, inorganic salt-enhanced flotation is expected to become a standard technology in the graphite processing industry, driving high-quality development of the graphite industrial chain.