Sodium sulfide (Na₂S) plays multiple roles in mining and mineral processing due to its chemical properties, serving as a critical reagent. Below are its specific applications and mechanisms:
I. Depressant for Sulfide Ore Flotation
Inhibition of Sulfide Minerals
High doses of sodium sulfide can depress the flotation of sulfide minerals such as galena, sphalerite, chalcopyrite, etc., with its inhibitory strength decreasing in the order:
Galena > Sphalerite > Chalcopyrite > Bornite > Pyrite > Chalcocite.
In molybdenum ore flotation, sodium sulfide suppresses gangue minerals like pyrite, enabling efficient separation of molybdenite when combined with collectors such as kerosene.
Selective Depression Mechanism
Sodium sulfide reacts with water to generate hydrophilic hydroxide films on mineral surfaces, reducing their floatability.
II. Sulfidizing Agent for Nonferrous Oxide Ores
Surface Sulfidization
Oxide ores of nonferrous metals (e.g., cerussite, malachite) cannot directly react with xanthate collectors. Sodium sulfide forms sulfide coatings on their surfaces, mimicking sulfide ore properties for flotation.
Sulfidization efficiency depends on pH (e.g., pH 8.5–9.5 for malachite), temperature, and agitation time.
III. Depressurizing Agent for Mixed Concentrates
Removal of Surface Collectors
Sodium sulfide desorbs xanthate collectors adsorbed on mineral surfaces, aiding in the separation of mixed concentrates (e.g., lead-zinc or copper-lead concentrates) before re-flotation.
Typical process steps:
Concentrate thickening → Sodium sulfide desorption → Washing → Re-pulping and flotation.
IV. Additional Auxiliary Functions
Precipitation of Harmful Metal Ions: Forms insoluble sulfides (e.g., PbS, HgS) to reduce interference from heavy metal ions in flotation.
Optimization of Flotation Environment: Adjusts slurry pH to alkaline ranges, enhancing reagent effectiveness.
Post time: May-16-2025
