The present study investigated the feasibility of the immobilisation of sulphate bearing radioactive wastes in blast furnace slag (BFS) based binders. BaSO4–BFS composites were produced via two methods using Na2SO4 as a waste simulant, along with Ba(OH)2 to promote precipitation of BaSO4 in an insoluble sulphate form and the consequent activation of the BFS. BaSO4 was effectively formed by both methods, and solid wasteforms were successfully produced. Although both methods produced BaSO4 embedded in the cement-like composites, different reaction products including ettringite and witherite were produced, depending on the order Ba(OH)2 was mixed with the system. These results show that the immobilisation of soluble sulphate-bearing aqueous wastes is achievable in Na2SO4–Ba(OH)2–BFS composites.
SobolevI, DmitrievS, LifanovF, KobelevA, StefanovskyS and OjovanM: ‘Vitrification processes for low, intermediate radioactive and mixed wastes’, Glass Technol. Eur. J. Glass Sci. Technol. A, 2005, 46A, 28–35.
2.
SharpJ, HillJ, MilestoneN and MillerE: ‘Cementitious systems for encapsulation of intermediate level waste’, Proc. 9th Int. Conf. on ‘Radioactive waste management and environmental remediation’, Oxford, UK, September 2003, ASME, 21–25.
3.
BinghamPA, HyattNC, HandRJ and WildingCR: ‘Glass development for vitrification of Wet Intermediate Level waste from Decomissioning of the Hinkley Point “A” site’, Mater. Res. Soc. Symp. Proc., 2009, 1124, 161–166.
4.
BinghamP and HandR: ‘Sulphate incorporation and glass formation in phosphate systems for nuclear and toxic waste immobilization’, Mater. Res. Bull., 2008, 43, 1679–1693.
5.
GollopRS and TaylorHFW: ‘Microstructural and microanalytical studies of sulfate attack. IV. Reactions of a slag cement paste with sodium and magnesium sulfate solutions’, Cem. Concr. Res., 1996, 26, 1013–1028.
GlasserFP: ‘Progress in the immobilization of radioactive wastes in cement’, Cem. Concr. Res., 1992, 22, 201–216.
8.
WuX, YenS, ShenX, TangM and YangL: ‘Alkali-activated slag cement based radioactive waste forms’, Cem. Concr. Res., 1991, 21, 16–20.
9.
ShiC and Fernández-JiménezA: ‘Stabilization/solidification of hazardous and radioactive wastes with alkali-activated cements’, J. Hazard. Mater. B, 2006, 137B, 1656–1663.
10.
MilestoneNB: ‘Reactions in cement encapsulated nuclear wastes: Need for toolbox of different cement types’, Adv. Appl. Ceram., 2006, 105, 13–20.
11.
BaiY, CollierN, MilestoneN and YangC: ‘The potential for using slags activated with near neutral salts as immobilisation matrices for nuclear wastes containing reactive metals’, J. Nucl. Mater., 2011, 413, 183–192.
12.
IpattiA: ‘Solidification of ion-exchange resins with alkali-activated blast-furnace slag’, Cem. Concr. Res., 1992, 22, 281–286.
13.
HanzlíčekT, SteinerovaM and StrakaP: ‘Radioactive metal isotopes stabilized in a geopolymer matrix: Determination of a leaching extract by a radiotracer method’, J. Am. Ceram. Soc., 2006, 89, 3541–3543.
14.
PierceEM, CantrellKJ, WestsikJH, ParkerKE, UmW, ValentaMM and SerneRJ: ‘Secondary waste form screening test results - Cast stone and alkali alumino-silicate geopolymer’, Report PNNL-19505, Pacific Northwest National Laboratory, 2010.
15.
W. Gong, W. Lutze and I. L. Pegg: ‘Low-temperature solidification of radioactive and hazardous wastes’, Patent, 2010. It should be: W. Gong, W. Lutze and I. L. Pegg: ‘Low-temperature solidification of radioactive and hazardous wastes’, US 7855313 B2, United States Patent, 2010.
16.
AsanoT, KawasakiT, HiguchiN and HorikawaY: ‘Feasibility study of solidification for low-level liquid waste generated by sulfuric acid elution treatment of spent ion exchange resin’, J. Power Energy Syst., 2008, 2, 206–214.
17.
EsenY and YilmazerB: ‘An investigation of X-ray and radio isotope energy absorption of heavyweight concretes containing barite’, Bull. Mater. Sci., 2011, 34, 169–175.
18.
Ben HahaM, Le SaoutG, WinnefeldF and LothenbachB: ‘Influence of activator type on hydration kinetics, hydrate assemblage and microstructural development of alkali activated blast-furnace slags’, Cem. Concr. Res., 2011, 41, 301–310.
19.
Alarcon-RuízL, PlatretG, MassieuE and EhrlacherA: ‘The use of thermal analysis in assessing the effect of temperature on a cement paste’, Cem. Concr. Res., 2005, 35, 609–613.
20.
HallC, BarnesP, BillimoreAD, JupeAC and TurrillasX: ‘Thermal decomposition of ettringite Ca6[Al(OH)6]2(SO4)3.26H2O’, J. Chem. Soc. Faraday Trans., 1996, 92, 2125–2129.
21.
MaciejewskiM, OswaldH.-R and RellerA: ‘Thermal transformations of vaterite and calcite’, Thermochim. Acta, 1994, 234, 315–328.
22.
ReyF and FornesV: ‘Thermal decomposition of hydrotalcites’, J. Chem. Soc. Faraday Trans., 1992, 88, 2233–2238.
23.
GausH and LutzeW: ‘Kinetics of strontium/barium and strontium/calcium ion exchange in synthetic zeolite A’, J. Phys. Chem., 1981, 85, 79–84.
24.
BernalS, SkibstedJ and HerfortD: ‘Hybrid binders based on alkali sulfate-activated Portland clinker and metakaolin’, XIII Int. Cong. on ‘The chemistry of cement’, Madrid, Spain, July 2011, CD-ROM proceedings.
