Recovery and concentration of buoyant cenospheres using an Inverted Reflux Classifier

• Published in: Fuel processing technology Vol. 123; pp. 127 - 139
• Main Authors: LI, J, AGARWAL, A, IVESON, S. M, KIANI, A, DICKINSON, J, ZHOU, J, GALVIN, K. P
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 01.07.2014
• Subjects: Applied sciences; Buoyancy; Byproducts; Cenospheres; Channels; Chemical engineering; Classifiers; Cross sections; Exact sciences and technology; Fly ash; Liquid-liquid and fluid-solid mechanical separations; Recovering; Separation; Density separation; Inverted Reflux Classifier; Buoyancy; Laboratory scale; Concentration; Density; Physical properties; Recovery; Pilot plant scale; Cenospheres; Fly ash; Suspended particle; Buoyant particles
• ISSN: 0378-3820; 1873-7188
• DOI: 10.1016/j.fuproc.2014.01.043

Cenospheres are hollow, low-density particles found in power station fly ash. They have many commercially-useful properties which make them a valuable by-product. However, recovering cenospheres from fly ash is difficult due to their low concentration and fine size. Experiments were performed to test the novel approach of using an Inverted Reflux Classifier. Inclined channels are mounted at the base to minimise the loss of buoyant cenospheres in the waste underflow stream. Experiments were performed at both laboratory scale (80mm x 100 mm cross-section) and pilot scale (300mm x 300mm cross section) using mixtures of cenospheres and silica, all nominally less than 100 pm in size. Both laboratory and pilot-scale units displayed similar behaviour and the results were also consistent with existing correlations for negatively-buoyant particles in the standard Reflux Classifier. Hence this technology has clear potential for recovering and concentrating cenospheres from fly ash.