2017 年 54 巻 9 号 p. 596-603
We examined about the chemical change of Japanese sea salt using Thermo Gravimetric and Mass Spectrometric analyzer (TG-MS). TG-MS spectrums of the salt, calcium chloride tetra-hydrate and magnesium chloride hexa-hydrate were measured. From the result, it’s thought that a formation of hydrogen chloride by heating the salt is caused by the chemical decomposition of magnesium chloride hydrate in general. On a temperature rising process, practical reaction temperature is increased with sample mass and heating rate. And the formation rate of the hydroxyl magnesium chloride and magnesium oxide is increased by moisture in a gas phase. The moisture in a gas phase cause oxidize anhydrous magnesium chloride to magnesium oxide around 500°C as shown in following reaction. MgCl2+H2O→MgO+2HCl. From these result, we concluded that control of residence time, gas-solid volume ratio and moisture in gas phase is important for reduce of hydrogen chloride formation in drying process and calcining process.
