Microwave heating behavior of blast furnace slag bearing high titanium

Blast furnace (BF) slag in south-western part of China contains large amount of titanium. For the purpose of beneficial utilization of titanium in the slag, microwave (MW) processing of the slag has been proposed. In this study, a fundamental research on heating behavior of the slag by application of 2.45 GHz MW was performed. The slag specimens can be heated in a domestic MW oven at constant input power (0.5kW) and sudden increase of the temperature is observed after several heating cycles. A phenomenon of so-called thermal runaway (TRW) occurred. A part of the specimen melted, and the XRD analysis indicated that this area became amorphous. Crystallization of the CaTiO₃ phase occurred by MW heating of the melted slag at 600°C. A sintered CaTiO ₃ compact was heated by MW much more than the synthetic Chinese slag. The synthetic slag without containing Ti was not heated very well. Permittivity of CaTiO₃ (loss factor) was measured and demonstrated to be much larger than the other oxides in the slag. Therefore, it is concluded that CaTiO₃ phase is responsible for heating of the whole slag.