To utilize the waste of the Erdenet (Mongolia) copper plant and mitigate the dust hazard, too, the waste was investigated together with ashes from Mongolian coal combustion power stations for the possibility of producing civil building materials. The ashes concern Banganuur fly ash (BFA) of the 4th thermal power station of Ulaanbaatar City, and pond ashes of the 3rd thermal power station of Ulannbaatar City (PAUB) and Darkhan City (PAD). Ashes and Erdenet floatation waste (EFW) were characterized with XRF, granulometry, XRD, SEM and gamma‐ray spectroscopy. The radium equivalent activity of EFW, BFA and PAD are below the value permitted for civil building materials (370 Bq/kg). It could be shown that the coal combustion by‐products alone could be alkali activated revealing binders of suitable 7 days compressive strength (in MPa) of about 30 (4.25), 8.25 (1.25), 3.24 (0.5) for BFA, PAUB, PAD, respectively. The EFW could be used as a full substitution of construction sand. For example the 7‐day compressive strength of alkali‐activated mortar containing 70% BFA and 30% EFW was 22.0 (4.69) MPa, while for the corresponding mortar prepared with construction sand it was 21.2 (5.5) MPa. So called “light‐weight concrete” were prepared in a special way using an in‐situ hydrogen release reaction with the addition of Al. Series were prepared with EFW as referenced to series with construction sand using alkali activated PAD as the binder. The results show systematic trends with compressive strength typically between 1 and 3 MPa