India is consulting until December 17, 2022 on a draft amendment to IS 797 Specification for Common Salt for Chemical Industries. IS 797 was first published in 1955 and subsequently underwent three revisions. The draft revision proposed to add instrumental test methods for the determination of sulphates, iron, magnesium and calcium, and update packaging and marking clauses.
IS 797 specified two grades of material, namely:
Grade 1— suitable for the manufacture of hydro sulfite and optical brighteners or where a pure grade of the material is required.
Grade 2— suitable for chemical industries, explosive and pyrotechnic industry and for the manufacture of caustic soda by electrolytic process.
As per IS 797, several ingredients of common salt used in chemical industries are subject to content requirements. Notably, iodide content was included as a newly restricted ingredient in this revision. The complete specifications are shown below:
| Characteristic | Requirements | |
| Grade 1 | Grade 2 | |
| Sodium chloride (as NaCl) | ≥99.5% | ≥98.5% |
| Matter insoluble in water | ≦0.05% | ≦0.2% |
| Calcium salts (as Ca) | ≦0.03% | ≦0.2% |
| Magnesium salts (as Mg) | ≦0.01% | ≦0.1% |
| Sulfates (as SO4) | ≦0.2% | ≦0.6% |
| Iron compound (as Fe) | ≦10ppm | ≦10ppm |
| Iodide contents (as I-) | ≦0.3ppm | ≦0.5ppm |
For use in the explosives and pyrotechnic industry, Grade 2 material shall meet the following additional requirements:
Sulfate≦0.5%
Iron≦10ppm
Alkalinity (as Na2CO3) ≦0.5%
For the manufacture of caustic soda by the electrolytic process, Grade 2 material shall meet the following additional requirements:
Vanadium + chromium + molybdenum≦0.01ppm
Aluminum (as Al)≦0.1ppm
Other trace metals like titanium, copper, and nickel≦0.01ppm
