Pure sodium sulfide anhydrous is in the form of white cubic crystals or particles, while industrial products are in the form of reddish brown or brick red lumps. It is extremely hygroscopic, easily oxidized and discolored in the air, toxic and unstable. Easily soluble in water, slightly soluble in alcohol, soluble in water (15.4g/100ml at 10 degrees Celsius, 57.2g/100ml at 90 degrees Celsius), the solution is alkaline. Slightly soluble in alcohol, insoluble in ether. It dissolves in water and becomes highly alkaline, which can cause burns when it touches the skin and hair, so it is also called sulfide alkali and smelly alkali. Dissolve in sulfur to form sodium polysulfide. Sodium sulfide is corrosive and toxic, and is easily oxidized in the air to form sodium thiosulfate. Sodium sulfide deliquesces in the air, carbonates and deteriorates, constantly releasing hydrogen sulfide gas. Industrial sodium sulfide contains impurities and its color is pink, brownish-red, or khaki. Its specific gravity, melting point, and boiling point also vary due to the influence of impurities. Sodium sulfide is produced by burning coal, charcoal, etc. as reducing gas to reduce sodium sulfate (Na2SO4+2C=Na2S+2CO2↑).
The most commonly used method for copper and molybdenum separation
Sodium sulfide is an activator for non-ferrous metal oxide ores, and when the amount added is large enough, it is also an inhibitor for sulfide ores.
Sodium sulfide method is the most commonly used method for separating copper and molybdenum. It can suppress all metal sulfide minerals other than molybdenum. Its dosage fluctuates widely, ranging from 2 to 30 kg/ton. fluctuation. It is more advantageous to add sodium sulfide in stages. A part of the sodium sulfide solution is often added to the stirring tank, while the other part of the sodium sulfide is placed in the rough and selected foam tank in solid form, and the heat emitted when the sodium sulfide is dissolved is used to make it. The temperature of the slurry is increased to enhance its inhibitory effect.
It is used as an inhibitor for sulfide ores in flotation operations. In the production practice of molybdenum separation, sodium sulfide is used to inhibit pyrite, and kerosene is used as a collector to flotate molybdenum. Ore, due to the good natural floatability of molybdenite, which is not inhibited by sodium sulfide, sodium sulfide inhibits pyrite, and qualified molybdenum concentrate is obtained after several selections.
When sodium sulfide is added to the slurry, the slurry becomes alkaline, causing a hydrophilic hydroxide film to form on the surface of the sulfide minerals and becoming hydrophilic, thus inhibiting the sulfide minerals.
Sodium sulfide also has some uses:
Used in the manufacture of sulfur dyes, leather depilatories, metal smelting, photography, rayon denitration, etc. Sodium sulfide is also widely used in tanning, papermaking, mineral processing, dye production, organic intermediates, printing and dyeing, pharmaceuticals, monosodium glutamate, man-made fibers, special engineering plastics, polyphenylene sulfide, polyalkali rubber, and is also used to make sodium hydrogen sulfide, Sodium polysulfide, sodium thiosulfate, etc. also have certain uses in the military industry.
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