Generally, the content of chloridion in natural gypsum is low, but chloridion are an important impurity component in desulfurized gypsum. Due to the recycling process of water and other water sources in the process of wet desulfurization and the development requirements of zero discharge of desulfurization wastewater, the chloridion in the desulfurization absorption tower are constantly enriched, resulting in high chlorine content in desulfurized gypsum.
In the process of preparation of gypsum mortar by highly chlorinated gypsum, chloridion will migrate along with the hydration reaction of gypsum, and finally combine with calcium ion on the surface of gypsum mortar to produce calcium chloride, which is easy to absorb water, resulting in the phenomenon of moisture return and yellowing when gypsum mortar is used.
At the same time, a large number of chloridion will affect the gypsum hydration process, and the setting time and make the strength of gypsum mortar do not meet the construction standards. In addition, chloridion will also have adverse effects on the water resistance of gypsum hydration products, the more chloride content, the greater the water absorption of gypsum hydrate, the smaller the softening coefficient.
