Heavy metal contamination in the vicinity of an industrial area near Bucharest

Heavy metals such as lead are well known to cause harmful health effects. Especially children are particularly susceptible to increased levels of lead in their blood. It is also a fact that lead concentration is increasing in the environment due to increased anthropogenic activity. The risk of heavy metal contamination is pronounced in the environment adjacent to large industrial complexes. In a combined case study, the environmental pollution by heavy metals was related to children's health in the vicinity of an industrial area located 4 km south-east from Bucharest about 2 km east from the nearest town-Pantelimon. This site includes companies processing different, nonferrous solid wastes for recovery of heavy metals and producing different nonferrous alloys and lead batteries. In this paper, mainly the results of environmental sampling and analyses are summarized

Influence of mechanical activation on the kinetics of non ferrous metal sulphides oxidation

The paper presents experimental research results on a new concept of oxidation in aqueous medium (solution of sodium carbonate) of copper sulphide concentrate in autoclave under air pressure in the temperature range 100 to 135 °C for 5 h, partial air pressure 5 aim in the presence of 30% excess of sodium carbonate more then stoichiometrical necessary for oxidation. Determinations were made in parallel on not-milled concentrate and mechanically activated concentrate. Based on the results obtained, the influence of mechanical activation on the kinetics of oxidation of sulphide concentrates was studied. By prolonged milling of copper concentrate, the activation energy decreases from 118.65 kJ · mol-1 to 25.75 kJ· mol -1.status: publishe

Mechanochemical activation of copper concentrate and the effect on oxidation of metal sulphides

This work presents the effect of mechanochemical activation in an attrition mill, in water medium and for different time internals, on the particle size distribution and microstructure of copper concentrate as well as, on the oxidation of the metal sulphides after treatment in an autoclave. Results show that the mean particle size decreased after 30 minutes of milling almost 10 times and the specific surface increased from 0.1 to 4.3 m2/g. Regarding the micro-structural changes, it was found that during the mechanochemical activation the average crystallite size of chalcopyrite decreased, following an exponential trend towards a limiting value of approximately 20 nm, assuming spherical or equiaxed crystallites. The enhanced structural disorder of chalcopyrite is also highlighted by the linear increase of lattice strain with the milling time. Finally, results from the leaching experiments, demonstrated that the mechanical treatment improved the oxidation of sulphides by lowering the reaction temperature and increasing the reaction rates. The above data suggest that the mechanochemical activation of copper concentrate is an efficient method to enhance the hydrometallurgical oxidation of copper concentrate and chalcopyrite in particular.status: publishe