Resistance to Grinding and Cement Paste Performance of Blends of Clinker, Limestone and Gypsum

Abstract

Grinding of finished cement is performed in a single stage, intergrinding materials with very different grindabilities. This intergrinding process has many different interactions among the different components of the finished cement. In a context of developing more sustainable and less energy intensive processes, it is important to understand the contribution of the individual components of cement mixtures to the overall energy consumption. A better understanding of the changes in resistance to grinding as a function of the mixture composition can aid to improve process throughput and efficiency. Therefore, understanding the relationship of the resistance to grinding of the cement components to the overall resistance when intergrinding is essential to optimize and reduce the energy consumption of these processes. Herein, we evaluate experimentally the interactions among clinker, limestone and gypsum during the final grinding stage in Portland cement production. We present a simple, yet rigorous, method that enables the determination of the individual grinding contributions to the intergrinding process. By using Rittinger’s KR parameter, our method is able to predict the contribution of the individual components even for blends with particle sizes below 100 µm. We used this model as the input for a nonlinear optimization that allowed for the identification of an optimum region of composition for Portland cement pastes, including restrictions to the heat of hydration and compressive strength development. The developed models can be easily adapted to aid in the formulation of cement blends with different characteristics to the raw materials used in this study.