Iodisation of Lake Katwe Salt, Kasese District

The raw rock salt was analysed for its chemical composition in terms of selected chemical species. It exhib- ited a large quantity of chemical impurities with sulphate at 20.7% w/w, carbonate 31.7 %, magnesium 945 ppm, iron 168 ppm, calcium 74 ppm and zinc at 18 ppm with chloride anion at 1.54% w/w. Titrimetry was used for determination of chloride and carbonates, sulphate was determined gravimetrically. ASS was used for determination of cations. Several methods were used for purification of the raw salt namely; fractional crystallization, precipitation with barium chloride, sodium state, potassium permanganate and ammonium sulphide. The purified salt had the following composition; carbonate 1.42% w/w, sulphate 3.83% chloride 50% w/w, iron 7.4±0.25, magnesium 7.64±0.20, calcium 4.40±0.30 and zinc 4.22±0.15. The refined salt was iodised at 100ppm by addition of (0.0356g) potassium iodate to 200 g salt. The level of the added iodine was determined by iodometric titration. It was found constant for two weeks (the experimental period).