Obtenção de clínquer Portland a partir da utilização do fino de rocha granítica (FRG) e do resíduo de telhas de cimento-amianto (RCA) como matérias-primas alternativas

Abstract

The Portland cement production process is responsible for high environmental impacts, with the exploration of deposits of these raw materials and emission of large amounts of CO2. In this context, the main objective of the present work was to analyze the technical feasibility of using granitic rock fines (GRF), waste generated in the process of producing aggregates for civil construction and asbestos cement waste tile (ACW), aimed at making Portland cement. Regarding the GRF, it was observed that there are no studies that aim to use this residue in the production of Portland clinker as a partial substitute for clay. As for the RCA, it was noted that there is a lack of research aimed at analyzing the potential of this residue as a mineralizer. For this, the raw materials were characterized physically, chemically and mineralogically and, based on these results, the production of two types of cement was proposed. First, the reference cement was produced, containing approximately 95% of limestone and 5% of clay, by mass, with clinkerization at a temperature of 1450 °C. Then, the second type of cement was produced, replacing FRG clay, in the contents of 25%, 50%, 75% and 100%, by mass, with clinkerization at a temperature of 1450 °C. In the production of the third type of cement, the limestone and clay mixture was replaced by RCA, at levels of 24%, 49%, 74% and 86%, by mass, with clinkerization at temperatures of 1450 °C, 1400 °C, 1350 °C and 1300 °C. The cements produced were characterized by physical-mechanical and expandability analysis, evaluation of hydration (calorimetry) and phase formation (XRD and Thermogravimetry). For cements produced with GRF it was observed that there was an increase in the alite content (C3S), when compared to the reference cement, and for those with 50% and 100% GRF content in the clinker flour, similar mechanical strengths were observed in the reference cement, although it does not impact CO2 emission. For cements produced with ACW, it was found that those produced at 1350°C and with 74% replacement of the clay-limestone mixture by ACW had mechanical resistance similar to that observed in the reference cement (without the addition of ACW), in addition to lower CO2 emission and energy consumption.