Alumina-enhanced valorization of ferronickel slag into refractory materials under microwave irradiation

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Department of Materials Science and Engineering


This study presents a new approach to enhance preparation of superior-quality refractory materials by microwave sintering of the mixture of ferronickel slag and sintered magnesia with addition of alumina up to 10 wt %. It was shown that in the process of microwave sintering, the proper addition of alumina could contribute to formation of forsterite with fine and relatively uniform particle size. It also promoted the generations of high melting point magnesium aluminate spinel (MgAl2O4), magnesium iron aluminate spinel (MgFe0.6Al1.4O4), and magnesium aluminum chromate spinel (MgAl0.5Cr1.5O4) which replaced magnesium chromate spinel (MgCr2O4) formed during sintering without addition of alumina, eventually improving refractoriness and other properties of the resulting refractory material. By adding 4 wt % alumina to the mixture of slag and 25 wt % sintered magnesia for sintering at 1250 °C in only 20 min, the resulting refractory material obtained refractoriness of 1790 °C. Compared with that prepared in the absence of alumina, the refractoriness was increased by 156 °C. The method proposed in this study has good potential in improving valorization of ferronickel slag into value-added materials, exhibiting both apparent economic and environmental benefits.

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Ceramics International