The bioleaching behavior of low-grade copper sulphides under the condition of preferential solution flow was investigated through experiments. The experiment of bioleaching was conducted within the multifunction autocontrol bioleaching apparatus. The results show that the concentrations of Cu2+ and total Fe increase slowly at the beginning. The recovery rate decreases with the increase of depth of dump. The preferential solution happens within the fine region when the application rate is low, and the recovery rate of the fine region is higher than that of the coarse region. The content of fine ore particles within both fine and coarse regions increases during the leaching period, and the preferential solution flow shifts from fine region to coarse region. The surface of the ores at the top of dump is attacked seriously, and the ores in the middle is attacked slightly. There are plenty of crackles on the surface of bottom ores because of the precipitation layer on the surface.
The column leaching experiment of ore granular media was carried out with the home-made multi-functional experimental apparatus and the pore structure of ore granular media was scanned by the X-ray computed tomography machine before and after leaching.The porosities of each section before and after leaching were calculated based on CT images processing,and the permeability of each zone before and after leaching were also calculated with Carman-Kozeny equation.The permeability evolvement law was disclosed.The results indicate that before leaching the permeability of the ore granular media in different height has not much difference and the value ranges from 5.70×10-4mm 2to 1.11×10 -3mm 2,where the lowest one locates in the bottom zone.After leaching the permeability distributes inhomogeneously along the height of the column and the value ranges from 3.44×10 -4 mm 2 to 2.25×10 -2 mm 2 ,where the lowest one is in the same place.Except for the bottom zone,the permeability of other zones increases after leaching,especially the top zone.Through comparison of the permeability at bottom zone before and after leaching,the whole permeability after leaching decreases by 39.65%that coincides with the measured experimental data.
The chalcopyrite anode dissolution behavior in the presence or absence of bacteria in 9 K media using bacteria modified powder microelectrode at 30 ℃ was studied. It is found that during the anode dissolution, many intermediate transient reactions occur accompanying with the production of chalcocite and covellite at potential between - 0.075 V and - 0.025 V (vs SCE). At low scanning potentialbetween - 0.1 and - 0.250 V, the iron ion is released in ferrous form, but at the relative high potentialup to 0.7 V, it is the ferric one. The presence of Thiobacillus ferrooxidans makes peak current increase and the initial peak potential negatively move, hinting the decomposed oxidation reaction easily occurred and especially the iron ion released and ferrous oxidation reaction enhanced. The characteristic at potential between - 0.75 and - 0.5 V demonstrates the Thiobacillus ferrooxidans also contributes to the element sulfur formed on the oxidation surface and removed during anode process. The added ferric in the cell could enhance the dissolution reaction, while the increased acid under pH=2 might slightly hamper the process. The anode dissolution kinetics studies show that the presence of bacteria could decease corrosion potential from 0.238 V to 0.184 V and increase the corrosion current density from 1.632 14×10- A/cm2 to 2.374 11×10- A/cm2.
