Sodium Sulfide is a frequently used agent in the flotation of sulfide ore. Its functions are mainly as follows:
When the amount is large, it can inhibit most of the sulfide ore. The descending order of its suppression of sulfide ore is roughly: galena, sphalerite, chalcopyrite, bornite, copper blue, pyrite, chalcocite. Due to the natural floatability of molybdenite, sodium sulfide cannot suppress it. Taking advantage of this, when flotation of molybdenite, Na2S can be used to inhibit other sulfide ores.
Non-ferrous metal oxide ore cannot be directly collected by xanthate. However, if sodium sulfide and non-ferrous metal oxide ore are added before the flotation of xanthate, a film of sulfide ore can be produced on the surface of the mineral, and the xanthate can be collected. This effect of Chinese Sodium Sulfide is called vulcanization, so it can be used as a vulcanizing agent for non-ferrous metal oxide ore.
After the white lead ore reacts with sodium sulfide, the surface color changes from white to darker. After the action of malachite and sodium sulfide, the surface color changes from green to dark black, indicating that after vulcanization, the surface of these two minerals has formed a sulfide film different from the mineral.
When the amount of sodium sulfide is large, it can resolve the xanthate collector on the surface of the adsorbed mineral. Therefore, sodium sulfide can be used as a de-agent before the separation of the mixed concentrate. For example, before the separation of lead-zinc mixed concentrate or copper-lead mixed concentrate, the pulp can be concentrated, added with a large amount of sodium sulfide for demedication, then washed, re-added fresh water to adjust the slurry, and then separated and floated.
In addition to the above three main functions, because sodium sulfide can form Insoluble Sulfide precipitation with many metal ions, sodium sulfide also has the effect of eliminating certain ions in the slurry that are harmful to flotation.