Optimization of the calcium silicate hydrated compounds synthesis from the recycling of material derived from coal industry waste

Abstract

The intensification of society's consumption and population growth are the main aspects that most contribute to negative impacts on living beings and environmental management due to the generation of large quantities of waste generated daily by industrial production processes. As a result, the valorization of these industrial by-products has been highlighted with the aim of obtaining value-added materials. The concepts of reuse and recycling are presented as a new production model aiming at more sustainable processes.: In the present work, the optimization of the synthesis of calcium silicate hydrated compounds was carried out from sulfated coal ash generated in the flue gas desulfurization process in a thermoelectric plant using the two-stage method (alkaline fusion followed by hydrothermal treatment). The studied parameters that influenced the synthesis were fusion time, agitation time, volume of water for the hydrothermal treatment of the samples, and two types of agitators (rod with blade-type propeller and shaking table). XRF and XRD characterized the ash and products. According to the characterization results, the highest crystallinity of calcium silicate hydrated compounds was identified in the product synthesized under the following conditions: fusion time of 3 h; volume of water for hydrothermal treatment of 100 mL; agitation time of 2 h agitator equipped with rod and blade-type propeller.: It can be concluded that sulfated ash is viable as a starting material for the formation of hydrated calcium silicate compounds, following the principles of environmental sustainability and the objectives of the circular economy.