NEW TOOL FOR ENVIRONMENTAL SAFETY DIAGNOSIS: CHEMICAL SIGNATURE OF AN ALUMINA REFINERY

Sustainability and environmental issues are becoming more important in the modern world and industries need to take actions to minimize their impact on natural resources and ecosystems. Normally, the evaluation of impacts on the external environment is done through self-monitoring, using limit values established in current resolutions as reference, like Resolution 357/2005 of the National Environmental Council (CONAMA), applied in Brazil to surface waters However, a chemical signature is more robust for assessing possible changes in the environment, identifying sources through multi-element analysis. The concept of a chemical signature involves analyzing elements in the various stages of a process, focusing on the overall inputs and outputs, determining the path that each one takes and the correlation between the elements at each point in the process. This concept has been made possible by advances in analytical techniques (ICP) combined with available statistical approaches, such as the Mantel Test. This work aims to develop a methodology to identify the chemical signature of the Alunorte alumina refinery, located in Brazil, to assess the possible impact of its raw materials, products and waste on the surrounding environment; and to achieve this objective, a sampling plan was carried out on the soil and water matrices. Alunorte operates in an open circuit, treating and discharging the effluent into a water body. The study was divided into four stages: i) identifying the components and chemical reactions of the Bayer process (literature); ii) collecting and analyzing samples (laboratory); iii) developing of statistical models and; iv) identifying of the trajectory of trace elements. One of the results of this work is that metals tend to concentrate mainly in the bauxite residue and ash, both of which are sent to bauxite residue disposal area (BRDA). Hypothesis tests revealed no significant correlation between the residue and effluent from the BRDA and the surrounding environment. In addition, no significant correlation was found between the treated effluent and the receiving water body. The methodology developed has not been explored in previous literature and can be a method for identifying possible contributions from the refinery to the environment.