Influence of cobalt ions on the anodic oxidation of a lead alloy under conditions typical of copper electrowinning

The influence of cobalt ions in the solution on the anodic oxidation of a commercial Pb–Ca–Sn alloy under conditions typical of copper electrowinning was studied using cyclic voltammograms and potential decay transients. The cobalt ions changed the structure, morphology and chemical composition of the surface film from a loose porous film to a thin dense film. This change of surface film is the cause for the decreased rate of oxidation for the lead anode in the presence of cobalt ions. The steady state potential of the alloy during anodic oxidation decreased with (i) increasing cobalt ion concentration, (ii) increasing rotation speed, (iii) increasing temperature, (iv) decreasing acid concentration and (v) decreasing current density. The steady state potentials were lower in the presence of cobalt ions. This decrease in the steady state potential may indicate that oxygen evolution is more rapid on the more compact film formed in the presence of cobalt ions. Alternatively, an additional pathway of oxidation may be provided by the cobalt ions

Importance of Effective Sampling and Test Work Protocols for Process Plant Design

IngenieursweseProsesingenieurswesePlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]

Leaching by ferric sulphate of raw and concentrated copper-zinc complex sulphide ores

A composite mixture of three typical Cu/Zn complex ores, namely black-, yellow- and altered-ore, from Cayeli deposit in Turkey, was used for leaching experiments under atmospheric pressure in ferric sulphate solutions, In order to study the reaction kinetics of the copper and zinc dissolution in the temperature range from 50 to 80-degrees-C; also in the presence of a solvent for elemental sulphur, such as CCl4. Owing to the fact that quite low copper extraction yields were obtained and to the clearly evident necessity of using pressure leaching in autoclave at higher temperatures, a tentative process of the ore enrichment by selective or bulk-flotation was then examined. Leaching tests in an autoclave at temperatures ranging from 100 to 230-degrees-C were carried out on the bulk-concentrate produced. Good extraction yields for both metals were achieved at 140-degrees-C after a few hours leaching by ferric sulphate

Importance of good sampling practice throughout the gold mine value chain

© 2016 Institute of Materials, Minerals and Mining and The AusIMM Published by Taylor & Francis on behalf of the Institute and The AusIMM.The mining industry routinely collects samples to assist with decision making, whether for exploration, resource estimation, grade control, or plant design and balances. Poorly designed sampling protocols can result in elevated project risk by increasing variability. Critically, such variability produces both financial and intangible losses. Sample collection, preparation and assay or test work protocols that are optimised to suit the ore type, together with QAQC systems will reduce variability. Many gold deposits display a high natural variability, where the in situ variability can be enhanced by poor sampling practice to yield a high-nugget effect. In this case, specialised protocols are often required. Reporting codes require the Competent Person to consider the quality and implication of sampling programmes. Despite its importance, sampling often does not receive the attention it deserves. In this paper, the importance of good sampling practice is exemplified through a series of case studies, which show the many sampling issues that frequently go unrecognised or unaddressed, resulting in poor decisions and financial loss

The impact of surgical delay on resectability of colorectal cancer: An international prospective cohort study

The SARS-CoV-2 pandemic has provided a unique opportunity to explore the impact of surgical delays on cancer resectability. This study aimed to compare resectability for colorectal cancer patients undergoing delayed versus non-delayed surgery