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Institutional Repository [SANDBOX]
Technical University of Crete
Technical University of Crete
EN
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EL
| URI: | http://purl.tuc.gr/dl/dias/3FAEBE56-9AE6-4830-A528-25256B2B9761 | ||
| Year | 2007 | ||
| Type of Item | Peer-Reviewed Journal Publication | ||
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| Bibliographic Citation | V. C. Kelessidis , G. Christidis , P. Makri ,V.Hadjistamou , C. Tsamantaki , A. Mihalakis ,C.Papanicolaou, A. Foscolos ,"Gelation of water–bentonite suspensions at high temperatures and rheological control with lignite addition " ,Ap. Clay Sc.,vol. 36.no.4 ,pp.221-231 ,2007.doi :10.1016/j.clay.2006.09.010 https://doi.org/10.1016/j.clay.2006.09.010 | ||
| Appears in Collections |
The effectiveness of lignite addition to prevent gelation of 6.42% w/w water–bentonite suspensions exposed to hightemperatures has been studied, using twenty six lignites from various basins in Greece with variable organic and inorganic contentsat concentrations of 0.5% and 3.0%. The lignite-free bentonite suspensions thickened considerably when heated at 177 °C for 16 h,as was indicated by a two-fold increase of the yield stress, when compared to samples hydrated only at room temperature. Howeverplastic viscosity did not change appreciably. Full flow curves showed a Herschel–Bulkley behavior of all suspensions. Addition oflignite maintained the stability of the suspensions exposed to high temperatures (177 °C) by keeping the yield stress low and didnot affect plastic viscosity. Some of the Greek lignites performed equally well with a commercial lignite product and improvementsof 80 to 100% of the stability of the suspensions, compared to lignite-free suspensions, have been found. Lignite addition alsolowered yield stresses for the hydrated samples. No specific trends have been identified between the effectiveness of lignites tostabilize bentonite suspensions and their humic and fulvic acids and humins content. However, those lignites with highest humicand fulvic acid contents have maximum stabilization capacity. Similarly, no specific trends have been observed between thestabilization capacity of lignites and their inorganic components such as oxygen and ash content and also with the cation exchangecapacity. The effectiveness of the Greek lignites to stabilize bentonite suspensions is very high and the minor differences in theefficiency of the different lignites cannot be attributed solely to any specific component
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