Produção de carbonato de cálcio provenientes de rejeitos de minério de Irecê: estudo experimental

Abstract

The concern for sustainability and industrial waste management, combined with the environmental, social, and economic demands of the sector, motivated this study on the production of CaCO₃ from fertilizer industry waste. The main objective is to reutilize lime sludge, a waste generated during the phosphate ore concentration process, and carbon dioxide (CO₂), a byproduct of ore calcination, to produce calcium carbonate. The study was conducted through a series of carbonation experiments, investigating the influence of operational variables such as solid content, CO₂ concentration, and mixing speed on reaction time and carbonate mass formation. A central composite design (CCD) was employed to optimize process conditions. The results demonstrated that increasing the CO₂ concentration from 12.5% to 30% and the solid content from 1.0% to 1.8% enhanced reaction efficiency. The optimized conditions for maximizing product yield and minimizing reaction time were a solid content of 1.75%, a mixing speed of 390 rpm, and a CO₂ concentration of 28.5%, achieving a process time of 28 minutes and a CaCO₃ mass of 13.52 g. The study confirms the technical feasibility of reusing waste materials such as lime sludge and CO₂, contributing to the development of sustainable processes aligned with circular economy principles and providing an alternative for the fertilizer industry and related sectors. This work reinforces the potential of sustainable practices in the fertilizer industry, offering an efficient solution for waste management and environmental liability reduction.