Sodium sulphide (Na2S) has several significant applications and uses in various industries. Some of the major applications of sodium sulfide include:

1. Chemical Manufacturing: Sodium sulfide is widely used in the production of other chemicals. It is used as a reducing agent in chemical processes, including the production of dyes, pigments, and pharmaceuticals.
2. Mining: In the mining industry, sodium sulfide is used for ore flotation. It helps separate valuable minerals from the surrounding rock by making the minerals more hydrophobic, allowing them to be collected more easily.
3. Textile Industry: Sodium sulfide is used in the textile industry for dehairing and scouring wool. It helps remove unwanted hair and impurities from the wool fibers, making them suitable for further processing.
4. Wastewater Treatment: Sodium sulfide is utilized in wastewater treatment plants to remove heavy metals from industrial and municipal wastewater. It forms insoluble metal sulfides, which can be easily removed from the water.
5. Paper Pulp Production: It is employed in the paper and pulp industry for the removal of lignin from wood chips during the papermaking process.
6. Leather Industry: In the leather industry, sodium sulfide is used for dehairing and deliming hides and skins. It helps prepare the material for tanning and other processing steps.
7. Photography: Sodium sulfide is used in photographic chemicals, specifically for toning black and white photographs.
8. Analytical Chemistry: It has applications in analytical chemistry for the detection and determination of various metal ions in solution.
9. Pyrotechnics: Sodium sulfide can be used in pyrotechnics to produce colored flames.
10. Petroleum Industry: In some cases, sodium sulfide can be used to remove impurities or contaminants from crude oil.