English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

that enables the economic processing of various types of low-grade ores in the copper industry, which could not otherwise be exploited (Ghorbani et al., 2011; Watling, 2006). In the case of secondary sulphide copper ores, heap leaching can offer a process alternative that is economically more attractive than the conventional concentration and smelting route. Compared to other extractive technologies, heap leaching is unique in that relatively large particles sizes are treated, typically 12–25 mm top size for crushed and agglomerated ores and larger for run-of mine dump leaching operations or in-situ leaching. Accordingly, despite much progress since it was first applied in recent times, the process remains limited by low recoveries and long extraction times. The rate of copper leaching and the extent of final copper recovery from heaps, dumps, and in situ operations are to a great extent limited by the limited access of leaching solutions to copper sulphide particles occluded in the gangue (Watling et al., 2014). Increased access of the solution to the copper sulphides can be gained by further reducing the ore particle size by crushing, when economically acceptable. In fact, a relationship between the percentage of copper minerals exposed with respect to particle size can provide a good basis for predicting copper recovery for a known particle size distribution (Miller et al., 2003; Dhawan et al., 2012). It would be economically advantageous to find ways of improving the leaching rate of copper minerals that remain occluded in the gangue without further reduction in particle size. The leaching rate is very slow as it depends on the diffusion of lixiviant and soluble products through gangue materials that encapsulate the copper minerals, and which can present very low natural porosity (Watling et al., 2014). Leaching improvements have been obtained by utilizing crushing techniques such as the highpressure grinding roll (HPGR), which induces a high level of microfracturing that increases diffusion rates in the gangue (Ghorbani et al., 2013). The influence of microfracturing produced by blasting on copper leaching recoveries has been also investigated (Parra et al., 2015). It is well known that during leaching there is an important degree of gangue dissolution under acid attack (Hiskey, 1992). This is shown by the incorporation of a wide variety of ions into the pregnant leach solution (Crundwell, 2015). However, little research has been done to study the influence that this dissolution process could have on the structure of the gangue and, eventually, on the mechanism of dissolution of copper mineral particles. The present work is part of a research programme aimed at identifying chemical and biological routes to improve the Physical and chemical transformations of gangue materials during leaching of copper sulphides, and their influence on copper leaching kinetics