Influência dos fatores experimentais no aumento da reatividade de um serpentinito na etapa de dissolução ácida do processo de carbonatação mineral
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Data
2021-08-17
Autores
Santos, Amanda da Silva
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Universidade Estadual Paulista (Unesp)
Resumo
O dióxido de carbono (CO2) faz parte dos gases classificados como GEE, sendo que o aumento na concentração de CO2 está diretamente relacionado com o aquecimento global. A fim de mitigar estas emissões, as tecnologias de captura e armazenamento de carbono (CCS - Carbon Capture and Storage) desempenham um importante papel na mitigação das emissões de CO2 na atmosfera. A carbonatação mineral é classificada como uma das tecnologias de CCS, na qual é baseada no processo natural de sequestro mineral de CO2, conhecido como desagregação das rochas, gerando produtos termodinâmicos e ambientalmente estáveis. A carbonatação aquosa indireta em meio ácido aplicada nesta pesquisa refere-se ao processo que ocorre em mais de uma etapa: 1) extração dos metais de interesse (dissolução ácida) presentes em minerais silicatos; 2) precipitação dos carbonatos. Esta pesquisa tem como objetivo avaliar a influência dos principais fatores que influenciam na etapa de dissolução ácida de um serpentinito brasileiro por meio da carbonatação mineral indireta, de forma a aumentar a eficiência de extração dos elementos de interesse (Mg e Fe) e favorecer a cinética de reação. Ensaios exploratórios e a técnica de planejamento de experimentos (Box-Behnken) foram aplicados. De acordo com os resultados obtidos, o fator tempo exerce influência significativa sobre a extração do magnésio e os fatores temperatura e tempo sobre o ferro. Os modelos desenvolvidos tanto para extração do magnésio como para o ferro apresentaram estatisticamente o coeficiente de rendimento satisfatório, além dos resultados previstos concordarem com os valores experimentais dos processos de dissolução com erro menor que 5%. As condições de melhor ajuste no processo de lixiviação dos elementos de interesse são representadas nas superfícies de resposta, sendo encontrado para a extração do magnésio valores em torno de 100 °C, 2,5 M e 180 min, para a temperatura, concentração do HCl e tempo, respectivamente (64,58%). Para a extração do ferro, as melhores condições de ajuste foram em torno de 100 °C, 2,5 M e 120 min, para a temperatura, concentração do HCl, respectivamente. Os resultados da matriz de Box-Behnken confirmam os resultados da análise exploratória mostrando que a metodologia empregada foi adequada.
Carbon dioxide (CO2) is part of the gases classified as GHG, and the increase in CO2 concentration is directly related to global warming. In order to mitigate these emissions, carbon capture and storage technologies (CCS) play an important role in mitigating CO2 emissions into the atmosphere. Mineral carbonation is classified as one of the CCS technologies based on the natural process of CO2 mineral sequestration, known as rock breakdown, generating thermodynamic and environmentally stable products. The indirect aqueous carbonation in the acidic medium applied in this research refers to the process in more than one step: 1) extraction of the metals of interest (acidic dissolution) present in silicate minerals; 2) carbonates precipitation. This research aims to evaluate the influence of the main factors influencing the acid dissolution stage of a Brazilian serpentinite through indirect mineral carbonation to increase the extraction efficiency of the elements of interest (Mg and Fe) and favor the kinetics of the reaction. Exploratory tests and the technique of planning experiments (Box-Behnken) will be applied. According to the results obtained, the time factor exerts a significant influence on magnesium and iron extraction, and the temperature exerts a significant influence only on iron extraction. The models developed for both magnesium and iron extraction statistically presented a satisfactory yield coefficient, in addition to the predicted results agreeing with the experimental values of the dissolution processes with an error of less than 5%. The best-fit conditions in the leaching process of the elements of interest are represented on the response surfaces, with values around 100 °C, 2.5 M and 180 min being found for temperature, HCl concentration and time, respectively, for magnesium extraction (64.58%). For iron extraction, the best adjustment conditions were around 100 °C, 2.5 M and 120 min, for temperature, HCl concentration, respectively. The results of the Box-Behnken matrix confirm the results of the exploratory analysis showing that the methodology used was adequate.
Carbon dioxide (CO2) is part of the gases classified as GHG, and the increase in CO2 concentration is directly related to global warming. In order to mitigate these emissions, carbon capture and storage technologies (CCS) play an important role in mitigating CO2 emissions into the atmosphere. Mineral carbonation is classified as one of the CCS technologies based on the natural process of CO2 mineral sequestration, known as rock breakdown, generating thermodynamic and environmentally stable products. The indirect aqueous carbonation in the acidic medium applied in this research refers to the process in more than one step: 1) extraction of the metals of interest (acidic dissolution) present in silicate minerals; 2) carbonates precipitation. This research aims to evaluate the influence of the main factors influencing the acid dissolution stage of a Brazilian serpentinite through indirect mineral carbonation to increase the extraction efficiency of the elements of interest (Mg and Fe) and favor the kinetics of the reaction. Exploratory tests and the technique of planning experiments (Box-Behnken) will be applied. According to the results obtained, the time factor exerts a significant influence on magnesium and iron extraction, and the temperature exerts a significant influence only on iron extraction. The models developed for both magnesium and iron extraction statistically presented a satisfactory yield coefficient, in addition to the predicted results agreeing with the experimental values of the dissolution processes with an error of less than 5%. The best-fit conditions in the leaching process of the elements of interest are represented on the response surfaces, with values around 100 °C, 2.5 M and 180 min being found for temperature, HCl concentration and time, respectively, for magnesium extraction (64.58%). For iron extraction, the best adjustment conditions were around 100 °C, 2.5 M and 120 min, for temperature, HCl concentration, respectively. The results of the Box-Behnken matrix confirm the results of the exploratory analysis showing that the methodology used was adequate.
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Palavras-chave
Carbonatação mineral, Captura de carbono, Serpentinito, Ensaios paramétricos, Planejamento de experimento, Box-Behnken, Mineral carbonation, Carbon capture, Serpentinite, Parametric assays, Experiment planning, Box-Behnken, Dióxido de carbono, Sequestro de carbono, Planejamento experimental