ISSN: 0149-6123
CODEN: CCAGPD
Page Count: 10

Role of Fly Ash and Aluminum Addition on Ettringite Formation in Lime-Remediated Mine Tailings
Mohamed, AMO
Associate Professor, Director, Research Support and Services Unit, Department of Civil and Environmental Engineering, UAE University,

Hassani, FP
Webster Professor of Mining Engineering, Director of Mining Engineering Program, McGill University, Quebec

Hossein, M
Project Manager, Hart Crowser Inc., New Jersey

Abstract

In this study, experiments were performed to evaluate the formation of ettringite in mine tailings samples treated with lime, fly ash type “C,” and aluminum. The success of the treated samples was evaluated based on results of X-ray diffraction and scanning electron microscopy. Using lime and fly ash, the preliminary investigation showed that addition of 5 % lime and 10 % fly ash constitutes the threshold of the treatment agents needed to form ettringite. However, long-term hydration resulted in lowering pH, and disintegration of formed ettringite. To overcome this problem, aluminum was added to the samples and formation of ettringite was monitored over a period of 660 days. Experimental results indicated that on availability of aluminum for reaction, primary and secondary ettringite minerals are formed and precipitated in these samples. Furthermore, the analysis indicated that the formed ettringite minerals remained stable during a hydration period of 660 days.

Keywords:
tailings, stabilization, solidification, lime, fly ash, aluminum, ettringite, calcium silica hydrate, gypsum, pyrite

Paper ID: CCA10443J
DOI: 10.1520/CCA10443J
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