Preparation of densified glass-ceramics with less shrinkage cavities from molten copper slag by Petrurgic method

Abstract

Petrurgic method is used to prepare glass-ceramics by directly controlling crystallization during the cooling process of the melts, which can realize the integrated utilization of both molten copper slag and its sensible heat. In this study, molten copper slag with no added agents was used to fabricate glass-ceramics using Petrurgic method. The temperature difference between the center and edges of molten copper slag with dimensions of 40 mm × 40 mm × 20 mm during the cooling process was measured, and its effects on crystallization and shrinkage cavities were studied. The results showed that the main phases of the glass-ceramics were magnetite and olivine, both of which crystallized significantly during the high-temperature cooling process. There were compact parts, transition parts and large cavity parts in the whole glass-ceramics and the cavities were caused by asynchronous crystallization of olivine owing to the temperature gradient distribution of the molten copper slag in the mold. Increasing the holding temperature during the heat treatment process reduced the temperature difference between the center and the edges and even inhibited the degree of crystallization, which further decreased the formation of shrinkage cavities. When the holding temperature was increased from 900 to 1150 °C, there were no longer large cavity parts in the non-compact parts but only transition parts. A higher holding temperature is thus beneficial for reducing the diameter of shrinkage cavities.