Crystal Growth on Cenospheres from High-Calcium Fly Ash

This work presents a study of cenosphere separation from lignite high-calcium (~24 wt.%) fly ash by centrifugal method; this is the first report for Mae Moh, Thailand, fly ash with this high calcium content using this technique. The effect of centrifugal parameters on cenosphere yield and properties were investigated. Those properties include physical properties, morphology, chemical composition, and mineral phases. The recovery yields are in the range of 0.34–0.64%, approximately one third of the yield obtained from the general gravity settling method. Density, particle size, and morphology of the collected cenospheres appeared to be independent of sequence of the applied speeds and times. Interrelation of chemical composition and mineral phases was established, with the focus on calcium carbonate formation on cenosphere surface and crystallite size study. The study has revealed the preferential formation of calcite–(104) peak is observed–by cenospheres, with stable growth behavior of crystallite sizes obtained from all the centrifugal conditions. The result was compared to that obtained from the sink-float method for a better insight. The influence and limitation of the centrifugal method, the varied parameters, and the relevant reaction pathways on crystal growth process in terms of important dissolving species (i.e., Ca2+ and CO32−) behavior in the ash suspension were discussed.

In Conclusion

The author draws from his position as editor of the Florida James Joyce Series to present twelve different new approaches to Joyce study. The book returns home by comparing the centrifugal method (departure) with the centripetal theme (return): Joyce’s departures are a cycle of fifths, which inexorably comes back to the home key. The twelve forewords given in this chapter are all centrifugal gestures, radiating outward in a series that has no limit. Concluding that universities in crisis must expand their definitions of research, teaching, and service, the author finds a home in the colleagues who have supported the Joycean enterprise. The book ends with a tribute to the best of Joyceans, Zack Bowen, whose approach models the empathy, collegiality, and hospitality that universities have forgotten.