a b s t r a c tA fresh green sand, spent green sand, and a weathered spent green sand (wSGS) from a foundry landfill were analyzed using diffractometry, electron microscopy, fluorometry, granulometry, spectrometry, and thermogravimetry (TG). Our objective was to understand how the physicochemical properties of the foundry green sands change from their original form after being subjected to the casting process, then after weathering at the landfill. A quantitative phase composition model was also postulated for each material based on the TG results and it was found to be the most reliable and informative quantitative data for this type of residue. The weathered sample, that remained in a landfill for two years, was found to be composed of almost pure sand. Because of the weathering process, it may be possible to use the wSGS as a virgin sand replacement in the regeneration system or in geotechnical applications where bentonite would affect the properties of the final product.Published by Elsevier B.V.
While most waste foundry sands (WFSs) are not hazardous, regulatory agencies are often reluctant to permit their beneficial use in agricultural and geotechnical applications due to concerns over metal leaching. The objective of this study was to quantify total and Toxicity Characteristic Leaching Procedure (TCLP) metals in 16 waste sands from Brazilian ferrous foundries then assess their potential to leach to groundwater using a probabilistic model. Total and TCLP metal concentrations in the non-hazardous sands fell within ranges as reported in the literature, although some of the leachate concentrations were found to exceed drinking water and groundwater maximum contaminant levels (MCLs). Leachate values above the MCLs were then used in the model to estimate groundwater concentrations at hypothetical wells up to 400m downgradient from a land application unit. A conservative scenario of 1 ha of land applied WFS, and high annual rainfall totals (low evaporation) suggested that groundwater concentrations of Ba, Hg, Mn, Ni, and Pb could potentially exceed health-based MCLs at most wells. While a wet climate can exacerbate the transport of metals, land application of WFSs in areas with moderate rainfall totals or high rainfall, high evaporation was predicted to be protective of groundwater quality and human health.
RESUMO A areia descartada de fundição (ADF), um dos resíduos provenientes do processo de fabricação de peças e componentes em fundições, é um material rico em sílica, derivado de uma composição com areia natural, bastante fino em comparação com a matéria-prima natural corrente e classificado, pela norma brasileira NBR 10004, como resíduo classe II A, resíduo não perigoso e não inerte. Por ter características físicas interessantes para ser utilizado como um substituinte do agregado miúdo natural na produção de materiais à base de cimento Portland, uma análise da ADF foi realizada buscando sua utilização em concretos de cimento Portland. Após análise morfo-físico química da ADF, testes de incorporação em concretos de cimento Portland foram feitos e avaliados os desempenhos em várias proporções de substituição. Como avaliação final, ensaios mecânicos e de lixiviação foram realizados nos concretos de ADF e os resultados indicaram que há perda de desempenho mecânico com o aumento do teor de ADF, mas essa perda pode ser considerada pequena quando comparada com o valor ambiental da utilização da ADF como substituinte ao agregado natural na produção de concretos.
Industrial dust emission is a kind of pollution which might occur due to the green sand mold process in the foundry industry. This material is predominately composed by sand, clay, carbon and metallic oxides. The ceramic industry has already assumed the role of consumer of by-products generated by such industries, mainly by having similarity between the composition of by-products and raw material employed in the ceramic sector. In a preliminary study the dust from exhaustion was define as a thin material with a high content of non-plastic material and the presence of carbon, which can interfere with processing and properties of the final product. This study aims to show the effect of exhaustion powder addition in atomized clay in order to develop ceramic coating. The results of the effect of sintering temperature and the percentage of residue on properties such as apparent density, linear shrinkage, water absorption and open porosity are presented.
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