TY - JOUR
T1 - Phase Formation and Evolution in Mg(OH)2-Zeolite Cements
AU - Walling, S.A.
AU - Bernal, S.A.
AU - Gardner, L.J.
AU - Kinoshita, H.
AU - Provis, J.L.
PY - 2018/1/24
Y1 - 2018/1/24
N2 - The mineralogy and structure of cements in the system Mg(OH)2–NaAlO2–SiO2–H2O are investigated, with a view toward potential application in the immobilization of Mg(OH)2-rich Magnox sludges resulting from historic United Kingdom nuclear operations. The reaction process leading to the formation of these aluminosilicate binders is strongly exothermic, initially forming zeolite NaA (LTA structure), which is metastable in low SiO2/Al2O3 binders, slowly evolving into the more stable sodalite and faujasite framework types. Notable chemical reaction of Mg(OH)2 was only identified in the formulation with SiO2/Al2O3 = 1.3 (the lowest molar ratio among those tested) after extended curing times. In this case, some of the Mg(OH)2 reacted to form an Mg–Al–OH layered double hydroxide. These results demonstrate that encapsulation of Magnox sludge waste streams could be carried out in these alternative binders but that the binders would encapsulate rather than chemically incorporate the Mg(OH)2 into the wasteform unless low SiO2/Al2O3 ratios are used.
AB - The mineralogy and structure of cements in the system Mg(OH)2–NaAlO2–SiO2–H2O are investigated, with a view toward potential application in the immobilization of Mg(OH)2-rich Magnox sludges resulting from historic United Kingdom nuclear operations. The reaction process leading to the formation of these aluminosilicate binders is strongly exothermic, initially forming zeolite NaA (LTA structure), which is metastable in low SiO2/Al2O3 binders, slowly evolving into the more stable sodalite and faujasite framework types. Notable chemical reaction of Mg(OH)2 was only identified in the formulation with SiO2/Al2O3 = 1.3 (the lowest molar ratio among those tested) after extended curing times. In this case, some of the Mg(OH)2 reacted to form an Mg–Al–OH layered double hydroxide. These results demonstrate that encapsulation of Magnox sludge waste streams could be carried out in these alternative binders but that the binders would encapsulate rather than chemically incorporate the Mg(OH)2 into the wasteform unless low SiO2/Al2O3 ratios are used.
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85042084882&partnerID=MN8TOARS
U2 - 10.1021/acs.iecr.7b04201
DO - 10.1021/acs.iecr.7b04201
M3 - Article
SN - 0888-5885
VL - 57
SP - 2105
EP - 2113
JO - Industrial and Engineering Chemistry Research
JF - Industrial and Engineering Chemistry Research
IS - 6
ER -