A Changing Environment: Reflections on 50 Years of Hydrometallurgy

Looking back over the past half century, it can be seen that the growth in the importance of hydrometallurgy for the production of non-ferrous and precious metals almost exactly parallels the rise of the environmental movement and its principal NGOs, such as Greenpeace and Friends of the Earth. The paper will review important landmarks in the development of the science and technology of hydrometallurgy and show how many of these have been influenced by pressures on the industry brought about by environmentalists. Successful innovations as well as commercial failures will be considered and reasons for the success or failure will be analysed and lessons drawn to guide future developments

THE SCORODITE PROCESS: A TECHNOLOGY FOR THE DISPOSAL OF ARSENIC IN THE 21ST CENTURY.

IN . (CASTRO S.H., F. AND SANCHE

Copper-gold ore processing with ion exchange and SART technology

Anglo Asian Mining has developed a 50,000 oz Au/yr open pit gold mine at Gedabek in Western Azerbaijan. The deposit at Gedabek is a copper-gold porphyry, comprising both oxide and sulphide ore mineralisation, which is being mined at the rate of about 1 million tons of ore per year. Ore processing is by conventional cyanide heap leaching, which produces a pregnant leach solution (PLS) containing 1-2 ppm of gold, together with 1000 ppm or more of copper. The PLS is treated by column ion exchange, using Dows gold-selective MINIX resin. Loaded resin is stripped with an acidic thiourea solution, from which gold and silver are electrowon on to stainless steel mesh cathodes. Copper concentrations in the leach solutions are controlled by passing part of the PLS flow through a SART process, where the acronym stands for Sulphidisation, Acidification, Recycling and Thickening . The product from the SART process is a copper/silver sulphide precipitate, which is thickened, filtered and dried and then sold for copper smelting. © 2014 Elsevier Ltd. All rights reserved

THE IRON ELEPHANT: A Brief History of Hydrometallurgists’ Struggles with Element No. 26.

The paper reviews the history of modern iron control processes in hydrometallurgy. Particular attention is paid to the processes developed in the 1960s by the electrolytic zinc industry for the removal of iron from zinc sulphate leach liquors - namely the Jarosite, Goethite and Hematite processes. Problems faced by the industry in the safe disposal of the iron residues produced by these processes are discussed. The lessons learnt over the past half century by the zinc industry are projected on to the current efforts to develop hydrometallurgical processes for the treatment of copper sulphide concentrates. It is argued that any attempt to create a “hydrometallurgical copper smelter” is doomed to ultimate failure, unless and until methods are developed that can recover iron from solution in a form that can be directly utilised by the steel or pigment industries

Industrial application of ammonia assisted cyanide leaching for copper-gold ores

A description of the agitation leach plant used for treating gold - copper ores a t Anglo Asian Mining’s Gedabek mine in Azerbaijan is given. The plant employs a unique resin - in - pulp system for gold recovery. The integration of the agitation leach plant into the existing heap leach/ADR/SART operation is described. Operational problem s caused by increasing amounts of copper in the Gedabek gold ores are outlined. Previous work on the use of ammonia in copper - gold cyanide leach systems is reviewed. T he test work leading to the introduction of ammonia in the industrial leaching plant is described. In the plant it was found that the extraction of copper was halved by the use of ammonia , thus leading to significant reductions in the amount of cyanide consumed in the full - scale leaching system

The influence of crystal orientation on the bacterial dissolution of pyrite

In order to understand the influence of crystallographic orientation on the mechanism of pyrite bioleaching, single crystals cut to expose plane orientations of (100), (111) and (110) were used for the study. Experiments to compare the extent of dissolution of the pyrite surfaces in the presence and absence of Acidithiobacillus ferrooxidans under similar solution conditions were undertaken by matching the conditions in abiotic solutions to those in bacterial leaching solutions using an electrolysis cell. The microbial corrosion patterns generated on the surfaces were further used to study the leaching process. Differences in the reaction rates of the pyrite surface planes in both abiotic and bacterial solutions have been observed. The results for the comparison between the bacterial and abiotic leaching of pyrite samples under similar conditions indicate higher dissolution rates in the presence of bacteria. In addition, the morphologies of corrosion patterns arising from microbial leaching were distinct from those of abiotic leached samples and were found to slightly differ from one crystal plane to another, while those in abiotic leaching generally reflected the symmetrical arrangement of the crystallographic planes in the lattice on which they formed. The results show that the surface properties of mineral sulphides control the evolution of corrosion patterns and the initial oxidation kinetics in acid bacterial leaching