The necessary drainage and dewatering system of the exhausted and closed Zn-Pb ore mines in the Bytom area in Poland can be treated as a process of in situ leaching of sparingly soluble minerals from the disturbed rock mass. The slimes obtained from the discharged water treatment are considered to be useless material. Currently, their management only increases the cost of water drainage process. The lack of interest in the apparently unattractive market product, and certain formal resistance, result in the fact that the dewatering technological line has not been closed at a level of the intentionally conducted process of in situ leaching. The paper presents the authors’ conception of winning useful, fine-grained limestone by modification of currently used technology of discharged water treatment from heavy metals (Zn, Pb and Cd). The essence of the process is receiving two products: cleaned water and mineral material having various possible applications.