Banca de QUALIFICAÇÃO: TIAGO FERNANDES DE OLIVEIRA
Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.DISCENTE : TIAGO FERNANDES DE OLIVEIRA
DATA : 06/09/2016
HORA: 08:00
LOCAL: SALA DE AULA DO NUPEG
TÍTULO:
"Synthesis and characterization of the mixed oxide of niobium and tantalum from columbite/tantalite"
PALAVRAS-CHAVES:
niobium and tantalum oxides, columbite/tantalite, leaching, precipitation
PÁGINAS: 75
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Química
RESUMO:
In this work were obtained a mixture of niobium and tantalum oxides from the ore columbite/tantalite extracted from Santa Cruz, RN. Initially the ore was prepared physically so that its composition and particle size were suitable for subsequent synthesis processes, passing thus through the grinding step, screening and quartering to homogenize the samples, followed by characterization by diffraction X-ray (XRD) and fluorescence of X-rays (XRF). Following the ore was leached for 8 hours at 70 °C for removal of iron and manganese present in their composition. To eliminate the tin which is present in high concentrations in the raw mineral, with percentages above 10% were conducted leaching for 8 hours at 50 °C and 90 °C in order to work with the thermal stability of cassiterite (SnO2), but there were no significant changes observed in its percentage in the treated mineral. Thus, new leaching was performed for 30 min at 70 °C with a mixture of 5M HF and H2SO4 0.5M to solubilize the oxides of Nb and Ta, and so separate them persistent impurity in mineral cassiterite. The hydrated oxides were characterized by fluorescence of X-ray (XRF), diffraction X-ray (XRD), thermogravimetric analysis and thermal differential (TG/DTA), infrared spectroscopy by Fourrier transform (FTIR), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The Nb and Ta oxides were precipitated with NH4OH and calcined at 800 °C for 5h and variable heating rate, 900 °C for 5h at 10 °C.min-1 to 1000 °C at a fixed heating rate of 10 °C.min-1 and time varying calcination was done for monitoring the crystallization of hydrated oxides obtained with the ammonia precipitation method. The mixed oxides of Nb and Ta were characterized by fluorescence X-ray (XRF), diffraction X-ray (XRD) with refinement by the Rietveld method and scanning electron microscopy (SEM). The influence of heating rate was observed in tests at 800 °C, evaluating rates of °C.min-1 5 °C and 10 °C.min-1. There was a higher crystallinity and the formation of new phases related peaks oxide as the calcination temperature increased. Thus, a comparative material was carried calcined at higher temperature study at 1000 °C, varying the calcination time 5h and 10h
MEMBROS DA BANCA:
Externo à Instituição - ARIADNE DE SOUZA SILVA - UFRN
Presidente - 349801 - CARLSON PEREIRA DE SOUZA
Externo à Instituição - CLEONILSON MAFRA BARBOSA - IFRN
Externo ao Programa - 345842 - UILAME UMBELINO GOMES