Copper leaching from nanoparticles of chalcopyrite concentrate

Abstract

In this research, the effect of mechanical activation, via ball milling, of copper sulfide concentrate on the efficiency and mechanism of copper leaching in an acidic ferric chloride solution was investigated. Copper concentrate, containing chalcopyrite as the main constituent, was supplied from Sarcheshme mine, located in the central part of Iran. By 24 hours of ball milling, the size of the concentrate particles was decreased to about 50 nm. The leaching of ball-milled samples was completed in a relatively more dilute solution and in shorter leaching times than that of unmilled samples. Ball milling of the concentrate from 0 to 180 minutes led to an increase in the efficiency of copper leaching in a acidic ferric chloride solution from 43 to 86%. Copper recovery was completed after 360, 540, 960, and 1440 minutes of leaching for the samples subjected to ball milling for 300, 240, 120, and 60 minutes, respectively. The activation energy of leaching process in the unmilled sample was 60.23 kJ/mol, while the activation energy of leaching for 24 hours of the ball-milled concentrate was 5.56 kJ/mol. The intensive decrease of activation energy after 24 hours ball milling was thought to be the result of the acceleration of the chemical reaction in very fine particles of the nanometrical scale. The low amount of activation energy suggested that the leaching rate controlling step was mass transfer in the concentrate milled for 24 hours.