Trapping of nickel and cobalt in CaNiSi2O6 and CaCoSi2O6 diopside-like phases in heat-treated cement

Niopside (CaNiSi2O6) and copside (CaCoSi2O6), diopside-like phases, were sy nthesized by ceramizing cementitious hydrates prepared by reaction between Ni- or Go-containing water solution and cementitious mix made of Ca3SiO5 pl us SiO2. Both niopside and copside exhibit very low leachability, which sho ws that these phases have potential for trapping nickel and cobalt, whose c ertain radionuclides (Ni-59, Ni-63, and Co-60) are activation products in m etallic structures of nuclear power plants. (C) 1998 Elsevier Science Limit ed. All rights reserved.