RESUMO
The sustainability of mining activities is compromised due to the high amounts of mining residues generated that have to be disposed of, often in open dams, that may cause environmental deterioration, e.g. release of toxic elements to water supplies. These residues are, however, secondary resources of raw materials. In the case of Panasqueira mine, they even are a source of tungsten, considered a critical raw material. The present work aims to assess the electrodialytic process efficiency for raw materials extraction from Panasqueira mine residues. Experiments were performed with 2 and 3-compartment electrodialytic reactors, applying current intensities between 50 and 100 mA, from 4 to 14 days, and sample suspensions enhanced with NaCl or effluent. Additionally, control experiments with no current application were carried out. The results showed that a 3-compartment reactor operating at 100 mA, with NaCl as supporting electrolyte, presented the highest extraction of copper (13%), tin (10%), tungsten (13%) and arsenic (63%).
RESUMO
The paper describes a heated furnace atomic absorption method for determining lead in whole blood using an automated sample introduction system. It is direct and rapid. No sample pretreatment is required and up to 30 samples per hour can be analyzed. Precision and accuracy data are presented. The system has been applied to both macro (venipuncture) and micro (capillary) samples. The method uses physiologically-bound lead standards to compensate for matrix effects. It has been used in the screening of target populations and for confirming elevated blood lead levels in the California Department of Health Services Childhood Lead Program.