In heap leaching, the oxidative dissolution of value minerals encapsulated deep within large particles cannot be fully understood on the basis of the bulk solution conditions relative to variable solution conditions near the mineral surface. In the present study, the diffusion of the oxidising species through inner particle pores is simulated in a model apparatus that separates an inert platinum electrode under controlled reduction potential from the bulk solution through narrow pores of varying length. The Cu-NH3 system was selected as a model system and Cu(II)/Cu(I) as the redox couple of interest. Platinum probes inserted in the pores allowed the measurement of varying redox potentials along the pore length. Results showed that in a 10 mm pore, there exists a narrow (0.5 mm) zone near the reduction surface that is depleted of the oxidant and in which its supply is strongly diffusion limited, even if it is in abundance in the bulk solution. The consistent presence of this narrow diffusion region across all experimental results indicated that the transportation of the reduced species away from the reaction surface had the most significant influence on the potential variations within the pore. This was further supported by the minimal effect of varying concentrations of both Cu(II) and dissolved oxygen on the solution potential within this region.
|Title of host publication||Extraction 2018|
|Subtitle of host publication||Proceedings of the First Global Conference on Extractive Metallurgy|
|Editors||Boyd R Davis, Jaeheon Lee, Michael S Moats, Graeme Miller, Shijie Wang, Jochen Petersen, Dean Gregurek, Virginia S T Ciminelli, Joël Kapusta, Qian Xu, Thomas P Battle, Ronald Molnar, Mark E Schlesinger, Jeff Adams, Gerardo Raul Alvear Flores, Wenying Liu, Evgueni Jak, Niels Verbaan, Graeme Goodall, John Goode, Michael L Free, Ian M London, Edouard Asselin, Gisele Azimi, Alexandre Chagnes, Alex Forstner, David Dreisinger, Ronel Kappes, Matthew Jeffrey, Tarun Bhambhani|
|Place of Publication||Cham Switzerland|
|Number of pages||12|
|Publication status||Published - 19 Aug 2018|
|Name||The Minerals, Metals & Materials Series|