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Bucharest, Romania

Onisei S.,Polytechnic University of Bucharest | Moldovan P.,Polytechnic University of Bucharest | Mara L.,INCDMNR IMNR | Predica V.,INCDMNR IMNR | Lupu C.,INCDMNR IMNR
UPB Scientific Bulletin, Series B: Chemistry and Materials Science | Year: 2010

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.

Onisei S.,Polytechnic University of Bucharest | Badilita V.,INCDMNR IMNR | Stoiciu F.,INCDMNR IMNR | Velea T.,INCDMNR IMNR | And 4 more authors.
Revista de Chimie | Year: 2012

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 m 2/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.

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