Low environmental impact cement produced entirely from industrial and mining waste

Abstract

Proper disposal of industrial waste, the need to conserve nonrenewable resources, and high CO2 emissions are the major environmental issues at the present time. A significant portion of emissions from portland cement production is related to the energy required to maintain the clinker kiln at a temperature of approximately 1,450°C, which is necessary for alite formation. The alternative belite phase, however, requires lower temperatures for its formation (below 1,250°C). Although belite is less reactive than alite, it is equally efficient at higher hydration times. Thus, a belitic cement produced entirely with industrial waste (grits from the pulp and paper industry, steel slag, and quartzite mining tailings) is presented in this research. The raw meal was proportioned based on Bogue calculation and the firing was performed in a muffle furnace at a temperature of 1,250°C. A reference belitic cement was produced with limestone and clay under the same conditions. The results showed that both cements presented high belite contents and expected technological performance. The reference belitic cement revealed a higher reactivity, whereas the waste cement proved to be a technically feasible low-impact alternative.