Effect of particle size on chalcocite dissolution kinetics in column leaching under controlled Eh and its implications
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Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China
University of Chinese Academy of Sciences, Beijing 10049, PR China
Wanbao Mining Ltd, Beijing 100053, PR China
Publication date: 2020-06-24
Corresponding author
Xiaopeng Niu   

Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China
Physicochem. Probl. Miner. Process. 2020;56(4):676-692
Natural high grade chalcocite samples were leached in column under controlled Eh, constant temperature and solution pH to investigate the effect of particle size on dissolution kinetics. Moreover, low grade ores of larger size fractions were leached in column using raffinate from the industrial heap as an irrigation solution to simulate the real heap conditions. The leaching rate of large particle sizes (31-200 mm) were very slow without inflection point which are normally present in the leaching of small particle sizes (0.054-31 mm). The effect of particle size was more remarkable in the dissolution of large particles than that of small particles during the first stage (<45% dissolution). However, the dissolution rate of the second stages (>45% dissolution) were not noticeably affected by the particle size. Results of kinetics analysis of leaching of small particles using shrinking core model indicated that the first stage was controlled by fluid diffusion and confirmed by the low activation energies (20.98 kJ/mol). The kinetics of second stage was controlled by chemical reaction and product layer diffusion and the later control became prominent with increasing particle size. Similarly, product layer diffusion was the rate-controlling step for the first and second stages of leaching of large particles. X-ray CT and SEM-EDS studies observed the increasing numbers of cracks and porosity and the formation of sulfur layer on the surface of the residue samples. The findings in this study provided some useful implications to optimize the heap performance and understand the leaching behavior of large particles.
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