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Leaching kinetics of copper from chalcopyrite concentrate in nitrous-sulfuric acid

Gok O., Anderson C. G., Cicekli G., Cocen E. L.

Physicochemical Problems of Mineral Processing

2014

Vol. 50, iss. 1

399--413

Treating chalcopyrite flotation concentrates by hydrometallurgical techniques seems to be the most convenient method for leaching copper due to concerns over air pollution and regulations regarding the emission of sulfur dioxide that result from smelting. In this study, the leaching recovery-time trajectories of bulk chalcopyrite concentrate obtained from a flotation plant in the Kastamonu region of Turkey are presented. The effects of various parameters were elucidated in the nitrous-sulfuric acid electrolyte (CNaNO2:0.05 M–0.15 M, CH2SO4:1 M) at a moderate temperature (80–120 °C). A high level of copper recovery (98%) from bulk chalcopyrite concentrate was obtained under a total pressure of 6 atm at 120°C within 2 h when using small amounts of nitrite species due to their autocatalytic behavior in acidic solutions. The kinetics were well correlated with the shrinking core model for the diffusion controlled mechanism with an apparent activation energy of 34.06 kJ·mol–1. Elemental sulfur was the primary leaching product on the mineral surface, as confirmed using XRD and SEM/EDX. The semi-empirical equation explaining the reaction rate under the present conditions was expressed as follows: ...[wzór].

Nitrogen species and macroelements in aerosols over the southern Baltic Sea

Nadstazik A., Marks R., Schulz M.

Oceanologia

2000

No. 42 (4)

411-424

The annual cycle of atmospheric nitrogen species and macroelements (Na+, K+, Ca2+, Mg2+ and Cl–) over the south-eastern Baltic region was investigated. A one-year record enabled the variability of nitrogen species and macroelements in the aerosol over the coastal station at Hel to be traced. The highest concentrations of sea salt components were recorded in summer, while anthropogenic nitrate concentrations were highest in winter. When the air masses were of mixed marine and continental origin, the nitric acid reacted with coarse sea salt particles to form stable, coarse sodium nitrate. This seems to be a permanent removal pathway for nitrate. Anthropogenic aerosol species like NH4+ or NO3– formed by gas-to-particle conversion were generally associated with fine particles (<1 žm). Coarse particles like sodium or chloride resulted from resuspension from seawater.