Upcycling of Slags from Ferrovanadium Production as Low-Carbon Footprint Cement for Refractory Castables

Abstract

Cement industry is responsible for almost 7% of the total CO₂ emissions, where 60% of them are caused by the unavoidable CaCO₃ calcination to produce Ca-bearing cementitious phases. Meanwhile, steel industry requires substantial amounts of ferrovanadium (FeV), that is produced by aluminothermic reduction, generating calcium aluminate (CA)-rich slags. The FeV slags that are generated contain MgO that is partially or fully incorporated into magnesium aluminate spinel structure. CA phases and MA are the main mineralogical phases in calcium magnesium aluminate (CMA) cements. This makes the FeV by-products suitable alternatives of CMA cement while promoting industrial symbiosis. CMA cement, unlike Portland cement, can be the exact type of cement that is dedicated in high-temperature applications such refractory lining of steel ladles. In this publication, industrial FeV slags were size reduced to match CMA particle size distribution and evaluated as substitutes of commercial CMA cement used for alumina-spinel castables. The refractoriness experiments and the mechanical tests proved that the novel cements are efficient substitutes of CMA. The hydration and also the mechanical behavior of FeV slag-bonded castables is as sufficient as the CMA-bonded castables.

Graphical Abstract