Recycling of spent magnesite and ZAS bricks for the production of new basic refractories

Changing environmental awareness and regulations, the cost of waste disposal, and concerns about future liabilities have caused increased interest in recycling of spent refractories. The densification parameters of spent magnesite containing up to 10.0 wt.% spent ZAS (zirconium aluminium silicate) sintered at 1450-1550 °C were investigated. X-ray, microstructure and microchemistry analysis were used to establish the present phases. The technological parameters in terms of RUL (refractoriness under load) and TSR (thermal shock resistance) of the prepared refractories attaining their maximum densification were evaluated. The results revealed that, the addition of spent ZAS up to 5.0 wt.% to spent magnesite enhanced the physico-mechanical, refractory and thermal properties due to the development of highly refractory phases MA spinel and MgO·ZrO2 solid solution. Samples containing more than 5.0 wt.% spent ZAS exhibited lower refractory and thermal properties due to the formation of M2S ferroan beside the high flux CMS phase.