Caracterização e processo produtivo da cal: estudo de caso do beneficiamento do calcário de uma companhia de mineração localizada na região da campanha do Rio Grande do Sul

Abstract

Lime is a product traditionally used in various processes. Different types of lime can be found in the market, and the variations occur due to the type of rock that originates the product and the production process, resulting in limes with distinct chemical and physical characteristics. The lime production process in a mining company involves the extraction of limestone from deposits, crushing and grinding of rocks, calcination, and classification. Factors influencing the quality of quicklime include the type of raw material, the calcination process, particle size distribution, impurity control, storage, and attention to environmental concerns. Studies emphasize the importance of these factors for the efficiency and quality of quicklime production, crucial variables. For the production of hydraulic lime, after calcination, the hydration process occurs, followed by mixing and classification for subsequent storage. Therefore, this study aimed to investigate the production process of quicklime and hydrated lime and characterize samples from an industry in the southern region of Rio Grande do Sul state to identify aspects that could be optimized. For this purpose, TGA data were obtained for Carbonate and hydrated lime, both showing the temperature at which the greatest mass loss occurred in the process. Quicklime was characterized through particle size analysis, obtaining an average diameter of around 80μm, fluorescence tests, and X-ray diffraction. In hydrated lime, a percentage of Ca 67.70% and Mg 25.36% was found, while in quicklime, a percentage of Ca 67.20% and Mg 26.78% was found. In XRD, compounds of Ca and Mg were found in both samples, in addition to CaO in quicklime and Ca(OH)2 in hydrated lime. In this way, it is highlighted that some improvements can be adopted so that the process has better performance, one of them would be the transformation of calcium carbonate into oxide, in addition, it is suggested that the company adopt a control of the oven temperature close to the temperature calcination.