Effect of the heat treatment on the morphology and sorption ability to metal ions of metallurgical slag

The effect of the phase composition of metallurgical slag on its ability to adsorb copper ions from aqueous solutions has been investigated. Granulated slag samples, mainly amorphous, have been pre-heated at 400, 600, 800 and 1000°C, then cooled slowly in the absence of moisture. Above 600°C crystallisation of a mineral gehlenite of the melilite group and of calcium silicates of the Ca2SiO4 structure type begins. The appearance of crystalline phases facilitates exchange and adsorption and the amount of copper adsorbed per a gram slag increasing about 2–4 times. The important role of the crystalline phases in the slag permits the synthesis of new materials adsorbing heavy metal ions on the basis of controlled liquid slag crystallization.