Potash salt ore goaf filling method

The invention discloses a potash salt ore goaf filling method, including the following steps: potash salt ore is subject to mineral separation, so as to obtain potash salt ore tailing; magnesium cement and the potash salt ore tailing are mixed and stirred into filling pulp; and the filling pulp is conveyed to potash salt ore goaf. According to the potash salt ore goaf filling process of the invention, pulp made by mixing magnesium cement and tailing is taken as filling main material, as the magnesium cement is mainly magnesium oxide, magnesium oxide water soluble magnesium salt is taken as gelling material, then water is added for blending, and air hardening gelled body, thus meeting the strength requirement of goaf filing.