Caracterização de resíduos industriais visando a seu aproveitamento na fabricação de aço

Esse trabalho consiste na caracterização do resíduo de mármore, lama fina de aciaria e borra de alumínio, para averiguar a viabilidade técnica da utilização de tais resíduos na dessulfuração e desfosforação de ferro-gusa líquido. A caracterização desses resíduos foi feita através de análises químicas, granulométricas, difração de raios X e microscopia eletrônica de varredura (MEV) com micro análise por Espectroscopia por Energia Dispersiva de Raios X (EDS). A lama fina de aciaria apresenta um teor de FeO de 84,90%, o resíduo de mármore apresentou um teor de 61,5% de CaO e 33,9% de MgO e a borra de alumínio apresentou 36,5% de Al metálico e 62% de Al2O3. A granulometria do resíduo de mármore apresentou um tamanho de grão médio igual 42,810 µm. Já, na borra de alumínio, o tamanho médio foi de 101,803 µm. A lama fina de aciaria LD apresentou, em torno de 54,7% de sua granulometria, entre 0,15 e 0,075mm. Esses resultados apontam para a viabilidade técnica da utilização desses materiais na dessulfuração e desfosforação do ferro-gusa.

Dephosphorization of Iron Ore through Bioleaching

Phosphorus, as phosphate, is frequently found as a constituent of many of the world iron resources. Phosphorus is an extremely harmful element found in iron ore used as a raw material in the steelmaking process because it will affect the quality of iron and steel products. Allowable phosphorus concentration in high quality steel is usually less than 0.08%. Dephosphorization of iron ore has been studied for a long time. Although there are described physical beneficiation and chemical leaching processes, involving inorganic acids, to reduce phosphorus content of iron ores, these processes have several limitations such as poor recovery, require high energy quantity, capital costs and cause environmental pollution. Use of microorganisms in leaching of mineral ores is gaining importance due to the implementation of stricter environmental rules. Microbes convert metal compounds into their water soluble forms and are biocatalysts of leaching processes. Biotechnology is considered as an eco-friendly, promising, and revolutionary solution to these problems. Microorganisms play a critical role in natural phosphorus cycle and the process of phosphate solubilization by microorganisms has been known for many years. This study was performed to analyze the possibility of using bioleaching as a process for the dephosphorization of an iron ore from Northeast of Portugal. For bioleaching, Acidithiobacillus ferrooxidans bacterium were used. For this study two experiments were done with different conditions, which lasts 6 weeks for first experiment and 5 weeks for second experiment. From the result of these preliminary studies, it was observed that for first experiment 6.2 % and for second experiment 3.7 % of phosphorus was removed from iron ore.