Análise dos factores que influenciam os teores de flúor na alumina secundária no Centro de Tratamento de gases da fundição de alumínio

Abstract

mThe efficiency of the Gas Treatment Center (CTG) in the aluminum industry depends directly on the stability of the fluorine content in secondary alumina, as the control of fluorinated compounds is essential to optimize fluoride recovery, the performance of reduction cells, and the consumption of raw materials in aluminum smelting. Maintaining the fluorine content in the ideal range of 1.7% to 1.9% is of strategic importance, as it ensures maximum adsorption efficiency in the CTG, promotes the effective recycling of fluorides in the electrolytic bath, reduces the consumption of fluorinated raw materials such as AlF3, positively impacting the performance and operational economy of the unit. In this context, the present work aimed to analyze the factors that influence the fluorine content in secondary alumina in the Gas Treatment Center of the aluminum smelter. Variables such as the particle size of primary alumina, feed rate, volumetric flow rate of the inlet gas, fluorine concentration in the gas, and number of high-level alarms in the filter funnels were analyzed. The study was complemented with statistical treatment of the data involving the Anderson-Darling, Kruskal-Wallis, and Spearman correlation tests, aiming to evaluate the distribution of the data and the relationships between the analyzed variables. The results indicated that the particle size of primary alumina showed a positive correlation with the fluorine content in secondary alumina, demonstrating that finer fractions favor the retention of fluorides. In contrast, the feed rate and the volumetric flow rate of the inlet gas showed a negative correlation, suggesting that higher values ​​of these variables contribute to greater removal of gaseous fluorides. The concentration of fluorine in the inlet gas and the high-level alarms showed a positive correlation, reflecting the direct influence of the fluoride load and material buildup on system efficiency. Analysis of real-time operational data, complemented by laboratory results, showed that the behavior of fluorine in the process depends on the balance between these operational variables and the properties of the raw material, making integrated management essential to ensure the efficiency of the CTG and the sustainability of the casting process. (TRADUÇÃO NOSSA)