Study on a New Process and its Kinetics of Iron Recovery and Glass-ceramics Preparation from Desulfurization Slag

The melting point and phase of slag was calculated with Factsage thermodynamics software, and base on this, taking desulfurization slag as the main raw material, which is leached by ammonium chloride as pretreatment. The composition of target slag system was adjusted with high aluminum powder coal ash and glass cullet, and then the reducing slag and metallic iron were separated by high temperature carbon thermal reaction. The prepared glass-ceramics with main crystal phases of diopside and nepheline were obtained by heat treatment, which shows that the new process is feasible. The crystallization activation energy was calculated by using Kissinger, Ozawa and Augis-Bennett method base on the differential heat curve. The results show that the crystallization activation energy is relatively high, and the crystal growth index n are all less than 3, which means that the crystallization capacity of the glass-ceramics is low. At the heating rate of 5 K/min, the n value of sample No. 3 is the largest, which is 2.7, and the mode of volumetric crystallization changes from two-dimensional to one-dimensional with the increase of heating rate, therefore, nucleating agent is needed in the preparation of glass-ceramics.