Synthesis and dissolution of slag minerals - a study of β-dicalcium silicate, pseudowollastonite and monticellite

Leaching of slag must be limited when slag is used in other areas than landfill. As slag is composed of different minerals, the properties of slag, inter alia the dissolution, depend on these minerals. If the leaching properties of each mineral are known, counter measurements can be taken to prevent the leaching of unwanted elements. In this study, the dissolution of three common slag minerals will be examined. The three minerals; boron-stabilised β-dicalcium silicate, pseudowollastonite and monticellite were synthesised. The dissolution was measured by setting pH to 4, 7 or 10 and adding 0.05 g mineral in the size range 20-38 mm and the HNO3 consumption required to maintain the pH level was recorded during 40 h. As expected, the dissolution increases for all minerals when pH decreases. The boron-stabilised β-dicalcium silicate was the only mineral fully dissolved at all pH levels, while pseudowollastonite and monticellite only dissolved completely at pH 4.On doit limiter le lessivage de la scorie lorsqu'...