Maycon Athayde

Distribuição e especiação de mercúrio em sedimentos de áreas de garimpo de ouro do quadrilátero ferrífero (MG)

The concentration and thermodesorption speciation of mercury in sediments from four different Iron Quadrangle sites impacted by gold mining activity were determined. The mercury content of some samples was considerably high (ranging from 0.04 to 1.1 µg g-1). Only Hg2+ was found and it was preferably distributed in the silt/clay fraction in all samples. Cluster analysis showed that mercury and manganese can be associated. The occurrence of cinnabar in this region as another mercury source was also discussed, corroborating earlier works showing the importance of natural mercury in the geochemical cycle of the metal in this region.

Iron ore pellet drying assisted by microwave: A kinetic evaluation

ABSTRACT Drying is a critical process step to achieve excellent pellet quality in pelletizing process. The complexity and energy consumption toward moisture removing, especially for highly hydrated iron ore, increased the need for breakthrough enhancements to this process. The present study has evaluated kinetics parameters of the moisture release from iron ore green pellet using energy transmitted through microwave (frequency of 2.45 GHz). The influence of pellet size and output power on the moisture effective diffusivity (Deff) and the drying activation energy (Ea) were evaluated. The results make possible to compare the cutting-edge approach with traditional convective drying. Pellet physical quality was investigated through the green crushing strength (GCS), which shows smooth reduction in earlier stages, however not affecting the final dry GCS results. Bonded hematite reduction and calcination of goethite was identified at the microstructure through reflected light microscopy, SEM showed micro cracks formation in several grains.

Case study of thermal profile design for traveling grate pellet furnace

ABSTRACT Production of iron ore pellets with enough strength to resist the transport and reduction on reactors requires an accurate adjustment of traveling grate furnace process parameters. The firing zone is the most energy intensive step to ensure quality and this study based on Lean Six Sigma methodology to evaluate and optimize the thermal profile through temperature fine-tuning. A pilot scale assessment aid to analyze physical, chemical, metallurgical and microstructure properties of pellets through different temperatures to accurate industrial implementation. The validation of lab-scale trials was concluded by industrial implementation to guarantee the quality, productivity and reduced costs.

A case study of pellet size fraction influence on pelletizing operation

ABSTRACT Pellet production is constantly optimized considering different aspects of the production chain from run of mining (ROM) to metallic iron. Industrially, the trade-off between an optimum pellet-size-ratio and the maximum performance in the steel production chain is a relevant subject. The present case study at a Brazilian operation shows the impact of different pellet size fractions on performance of operation, improvements on the fired pellets, less fine generation during handling, and superior metallurgical behavior during the reduction process, resulting in the production of direct reduction iron (DRI) that add more value to the economic performance of the electric arc furnaces (EAF).