Obtención de vidrio a partir de residuos de la minería del estaño en Bolivia

Manufacturing of glass from tin mining tailings in Bolivia Tailings from mining activities in Bolivia represent an environmental problem. In the vicinity of the tin mines of Llallagua,Potosí department, there are large dumps and tailings. We present a study of the use of these wastes as raw materials for the manufacture of glass. This procedure aims to contribute to environmental remediation of mining areas through the vitrification, a process which offers an alternative for stabilization of hazardous waste. In addition, the marketing of the obtained product would provide an additional income to the mining areas. For this study three samples of mining waste, with grain size between sand and silt, were used. The chemical composition of these raw materials, determined by X-ray fluorescence, is granitic, with high contents of heavy metals. On the basis of its composition, glass were made from silica glass by adding CaCO3 and Na2CO3. The thermal cycle has been determined from TDA. Tg values of glass range from 626º to 709 °C. Leaching tests of the obtained glasses confirm their capacity to retain heavy metals.

Obtención de vidrio a partir de residuos de la minería del estaño en Bolivia

Manufacturing of glass from tin mining tailings in Bolivia Tailings from mining activities in Bolivia represent an environmental problem. In the vicinity of the tin mines of Llallagua,Potosí department, there are large dumps and tailings. We present a study of the use of these wastes as raw materials for the manufacture of glass. This procedure aims to contribute to environmental remediation of mining areas through the vitrification, a process which offers an alternative for stabilization of hazardous waste. In addition, the marketing of the obtained product would provide an additional income to the mining areas. For this study three samples of mining waste, with grain size between sand and silt, were used. The chemical composition of these raw materials, determined by X-ray fluorescence, is granitic, with high contents of heavy metals. On the basis of its composition, glass were made from silica glass by adding CaCO3 and Na2CO3. The thermal cycle has been determined from TDA. Tg values of glass range from 626º to 709 °C. Leaching tests of the obtained glasses confirm their capacity to retain heavy metals.

Dilemas implicativos, psicopatologia e construção do self: mudança durante o primeiro ano da Universidade.

O objectivo deste estudo foi comparar os indicadores de sintomatologia psicológica, competências de resolução de problemas e de construção pessoal, quando avaliados no início e no final do primeiro ano da Universidade. Analisámos também os preditores quer de sintomatologia psicológica, quer de competências de resolução de problemas avaliadas no final do ano lectivo. Vinte e oito estudantes do primeiro ano da Universidade do Minho, preencheram uma medida de sintomatologia psicológica (SCL-90-R), uma medida de competências de resolução de problemas (IRP) e a grelha de repertório para análise da sua construção pessoal. Os resultados indicam uma diminuição significativa na sintomatologia e um aumento significativo da auto-estima, no segundo período de avaliação. Verificámos que a sintomatologia e as competências manifestadas no início do ano são, respectivamente, os melhores preditores de sintomatologia e competências no final do ano. Os resultados são discutidos sublinhando as implicações para a promoção da adaptação dos estudantes universitários.