147 results found
Colombo C, Oates C J, Monhemius A J, et al., 2022, Complexation of platinum, palladium and rhodium with inorganic ligands inthe environment., Geochem. Explor. Envir. Analysis.
Aliyev R, Hedjazi F, Westhead SJ, et al., 2019, The use of geometallurgy in the processing of a complex copper-gold ore deposit, 15th SGA Biennial Meeting on Life with Ore Deposits on Earth, Publisher: SOC GEOLOGY APPLIED MINERAL DEPOSITS-SGA, Pages: 1490-1493
Hedjazi F, Monhemius AJ, 2018, Industrial application of ammonia-assisted cyanide leaching for copper-gold ores, MINERALS ENGINEERING, Vol: 126, Pages: 123-129, ISSN: 0892-6875
Hedjazi F, Monhemius AJ, 2018, The industrial application of ultrafiltration and reverse osmosis for the recovery of copper, silver and cyanide from gold leach liquors., Extraction 2018, Publisher: Springer Nature Switzerland AG, Pages: 1883-1891
Anglo Asian Mining have recently installed an industrial-scale UF/RO plant to treat process liquors from the integrated heap leach/agitation leach/resin-in-pulp gold ore treatment facilities at their Gedabek gold-copper mine in Azerbaijan. The UF/RO plant is designed to treat 60 cu.m/hr of leach solution to produce discharge quality water. The RO concentrate, which contains elevated concentrations of copper, silver and cyanide, is sent to the company’s SART plant for the recovery of the metal values as a precipitated sulphide concentrate and the cyanide, which is recycled to leaching. The new water treatment plant improves the sustainability of the operations at Gedabek by enabling replacement of fresh water input with RO permeate and safe discharge of permeate to the environment, during periods of excess water balance. The paper includes pilot plant data and early results from the full-scale plant.
Monhemius AJ, Hedjazi F, Saeedi Ali H, 2017, Flotation and leaching at Anglo Asian mining’s Gedabek gold and copper mine in Azerbaijan, COM2017 | The Conference of Metallurgists, hosting World Gold & Nickel Cobalt, Publisher: Canadian Institute of Mining, Metallurgy and Petroleum
Anglo Asian Mining’s Gedabek mine is situated in the Lesser Caucasus mountains in Western Azerbaijan. The ore body is a complex copper-gold porphyry deposit, comprising intermixed oxidized, transition and sulphidic gold and copper-bearing ores. Gold in the sulphide ores is generally not refractory and is recoverable by cyanide leaching, but the secondary copper minerals, which are also cyanide soluble, lead to high cyanide consumptions. Ore processing at Gedabek is by agitation leaching for high grade ore (>1g Au/t) and heap leaching for lower grade ore. In order to cope with the high copper concentrations in the cyanide leach liquors, a unique combination of resin-in-pulp for selective gold extraction and SART processing for copper removal and cyanide recovery is used. In 2015, a flotation plant was added to treat the tailings from the agitation leach plant before the tails are sent to the tailings dam. This plant produces a copper sulphide flotation concentrate and also recovers some of the residual gold and silver in the tailings. Since February 2017, due to lower grades of gold and higher copper in the feed ore, the decision was taken to alter the flow sheet and to carry out flotation ahead of agitation leaching, to reduce the cyanide consumption during leaching by removing soluble copper minerals. The paper compares and contrasts the performance of the plant in the two configurations, namely, (i) leaching followed by flotation and (ii) flotation followed by leaching.
Monhemius AJ, 2016, THE IRON ELEPHANT: A Brief History of Hydrometallurgists’ Struggles with Element No. 26., XXVIII International Mineral Processing Congress
The paper reviews the history of modern iron control processes in hydrometallurgy. Particularattention is paid to the processes developed in the 1960s by the electrolytic zinc industry for theremoval of iron from zinc sulphate leach liquors - namely the Jarosite, Goethite and Hematiteprocesses. Problems faced by the industry in the safe disposal of the iron residues produced by theseprocesses are discussed. The lessons learnt over the past half century by the zinc industry are projectedon to the current efforts to develop hydrometallurgical processes for the treatment of copper sulphideconcentrates. It is argued that any attempt to create a “hydrometallurgical copper smelter” is doomedto ultimate failure, unless and until methods are developed that can recover iron from solution in a formthat can be directly utilised by the steel or pigment industries.
Monhemius AJ, 2016, 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.
Hedjazi F, Monhemius AJ, 2014, Copper-gold ore processing with ion exchange and SART technology, MINERALS ENGINEERING, Vol: 64, Pages: 120-125, ISSN: 0892-6875
Monhemius AJ, 2014, A Changing Environment: Reflections on 50 Years of Hydrometallurgy, HYDRO 2014 Hydrometallurgy Conference, Publisher: Canadian Institute of Mining, Metallurgy and Petroleum
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.
Hedjazi F, Monhemius AJ, 2013, Copper-gold ore processing with ion exchange and SART technology at Anglo Asian's Gedabek mine in Azerbaijan, Pages: 1385-1393
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 Dow's 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".
Moradi S, Monhemius AJ, 2011, Mixed sulphide-oxide lead and zinc ores: Problems and solutions, MINERALS ENGINEERING, Vol: 24, Pages: 1062-1076, ISSN: 0892-6875
Colombo C, Monhemius AJ, Plant JA, 2008, Platinum, palladium and rhodium release from vehicle exhaust catalysts and road dust exposed to simulated lung fluids, ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY, Vol: 71, Pages: 722-730, ISSN: 0147-6513
Colombo C, Oates CJ, Monhemius AJ, et al., 2008, Complexation of platinum, palladium and rhodium with inorganic ligands in the environment, Workshop on Environmental Geochemistry - Site Characterization, Waste Disposal, Data Analysis, Case Histories, Pages: 91-101
Platinum (Pt), palladium (Pd) and rhodium (Rh) are emitted by vehicle exhaust catalysts (VECs) and their concentrations have increased significantly in various environmental compartments, including airborne particulate matter, soil, roadside dust, vegetation, rivers and oceanic environments, over the last two decades as the use of VECs has increased. However, data on the chemical speciation of the platinum-group elements (PGEs) and their bioavailabilities are limited. In this paper, the thermodynamic computer model, HSC, has been used to predict the interactions of Pt, Pd and Rh with different inorganic ligands and to estimate the thermodynamic stability of these species in the environment. Eh-pH diagrams for the PGEs in aqueous systems under ambient conditions (25 degrees C and 1 bar) in the presence of Cl, N and S species have been prepared. The results indicate that Pt, Pd and Rh can form complexes with all of the inorganic ions studied, suggesting that they are capable of mobilizing the PGEs as aqueous complexes that can be transported easily in environmental and biological systems and that are able to enter the food chain. Hydroxide species can contribute to the transport of PGEs in oxidizing environments such as road-runoff waters, freshwater, seawater and soil solutions, whereas bisulphide complexes could transport Pt and Pd in reducing environments. Ammonia species appear to be significant under near-neutral to basic oxidizing conditions. Chloride species are likely to be important under oxidizing, acidic and saline environments such as seawater and road-runoff waters in snowmelt conditions. Mixed ammonia-chloride species may also contribute to the transport of Pt and Pd in highly saline solutions.
Colombo C, Monhemius AJ, Plant JA, 2008, The estimation of the bioavailabilities of platinum, palladium and rhodium in vehicle exhaust catalysts and road dusts using a physiologically based extraction test, SCIENCE OF THE TOTAL ENVIRONMENT, Vol: 389, Pages: 46-51, ISSN: 0048-9697
Lewis RA, Monhemius AJ, Plant JA, 2007, Low temperature nucleation of ferric arsenate using microorganisms, 17th Annual V M Goldschmidt Conference, Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: A567-A567, ISSN: 0016-7037
Colombo C, Plant JA, Monhemius AJ, 2007, Impact of vehicle-emitted platinum group elements on the human respiratory and digestive tracts, 17th Annual V M Goldschmidt Conference, Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: A183-A183
Naden J, Herrington RJ, Jowitt SM, et al., 2006, New methodologies for volcanic-hosted copper sulphide mineralization on Cyprus: A GIS–prospectivity analysis-based approach, Report of the British Geological Survey, CR/06/129
Monhemius AJ, 2006, Life cycle and process analysis in the mining industry, JOURNAL OF CLEANER PRODUCTION, Vol: 14, Pages: 1040-1041
Monhemius J, 2006, Section 1: life cycle and process analysis in the mining industry, JOURNAL OF CLEANER PRODUCTION, Vol: 14, Pages: 1040-1041, ISSN: 0959-6526
Hilson G, Monhemius AJ, 2006, Alternatives to cyanide in the gold mining industry: what prospects for the future, JOURNAL OF CLEANER PRODUCTION, Vol: 14, Pages: 1158-1167, ISSN: 0959-6526
Ndlovu S, Monhemius AJ, 2005, The influence of crystal orientation on the bacterial dissolution of pyrite, Hydrometallurgy, Vol: 78, Pages: 187-197, ISSN: 0304-386X
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.
Wu XQ, Monhemius AJ, Gochin R, 2005, Quantitative assessment of hydrophobic agglomeration performance, MINERALS ENGINEERING, Vol: 18, Pages: 567-573, ISSN: 0892-6875
Swash PM, Monhemius AJ, 2005, Characteristics and stabilities of residues from the Wheal Jane constructed wetlands, SCIENCE OF THE TOTAL ENVIRONMENT, Vol: 338, Pages: 95-105, ISSN: 0048-9697
Hilson GM, Monhemius AJ, Rautiu R, 2005, Alternative leach reagents in gold processing – a review of substitutes for cyanide, Gold Extraction in Central and Eastern Europe.and the Commonwealth of Independent States, Editors: Ranft, Pesch, Vogt, Publisher: Jagiellonian University Press, Pages: 181-206
Wu XQ, Gochin RJ, Monhemius AJ, 2004, Modelling gold particle adhesion to oil-carbon agglomerates, INTERNATIONAL JOURNAL OF MINERAL PROCESSING, Vol: 74, Pages: 327-336, ISSN: 0301-7516
Ndlovu S, Monhemius AJ, 2004, The role of orientation of crystal lattice on the development of bacterial leaching patterns on pyrite single crystals, Journal of the Southern African Institute of Mining and Metallurgy, Vol: 104, Pages: 573-578, ISSN: 2225-6253
To investigate the influence of orientation of crystal lattice on thebacterial leaching of pyrite crystals, single crystals of 100, 111 and110 plane orientations were used for the study. Experiments werecarried out in the presence of a Thiobacillus ferrooxidansculture.The different corrosion patterns observed on the surfaces of thebioleached samples suggests a variation in cell-surface interactionfrom one crystal plane to the other. The surface corrosion patternsgenerally reflected the influence of the symmetrical arrangement ofthe atomic planes in the lattice on which they formed. The resultsindicate that the surface properties of mineral sulphides may controlthe evolution of corrosion patterns and consequently the initialoxidation process in acid bacterial leaching.
Georgaki I, Dudeney AWL, Monhemius AJ, 2004, Characterisation of iron-rich sludge: correlations between reactivity, density and structure, Meeting on Processing and Disposal of Minerals Industry Wastes 2003, Publisher: Elsevier, Pages: 305-316, ISSN: 1872-9444
This paper discusses the behaviour of iron-rich sludge, a problematic waste product of potable water treatment, minewater/groundwater management and hydrometallurgical processing. The work confirmed the highly hydrous and largely amorphous nature of the sludge and the significant differences that occur in reactivity (rate of acid leaching) and density (densification) depending variously upon the mode of sludge formation, pre-conditioning and storage. A structural study using a combination of FT-IR/ATR, XRD and TG/DTA correlated decreases in reactivity with ageing (i.e., with increases in particle size and/or degree of crystallinity) and increases in density with expulsion of weakly bonded water. The work underpinned studies on recycling of water treatment sludge with ion exchange resins and accelerated densification during sludge management.
Palacios EG, Juárez-López G, Monhemius AJ, 2004, Infrared spectroscopy of metal carboxylates -: II.: Analysis of Fe(III), Ni and Zn carboxylate solutions, HYDROMETALLURGY, Vol: 72, Pages: 139-148, ISSN: 0304-386X
Wu XQ, Gochin RJ, Monhemius AJ, 2004, The adhesion of gold to oil-carbon agglomerates, Minerals Engineering, Vol: 17, Pages: 33-38, ISSN: 0892-6875
The adhesion behaviour of gold particles to agglomerates of oil and carbon and the dynamic changes of the agglomerates during the contact process have been investigated. It is shown that the rate of adhesion of gold particles to agglomerates can be significantly increased by using xanthate collectors. It is further demonstrated that the longer the hydrocarbon chain of the xanthate molecule, the greater the rate of adhesion of gold to the agglomerates. The adsorbed gold particles do not markedly affect the adsorption activity of the agglomerates, i.e. recycling the agglomerates to increase the gold loading is feasible. Examination of gold-loaded agglomerates by scanning electron microscopy showed that in addition to individual gold particles, gold “flocs” and even “micro-nuggets” can be detected on the agglomerates. These flocs and nuggets are probably formed by the movement of initially adsorbed gold particles over the surface of the agglomerates. Both the composition and structure of the agglomerates change during the contact process. The oil tends to diffuse out of the agglomerates, and their oil content decreases with agitation. The gold particles can also migrate into the interior of the agglomerates due to their deformation resulting from agitation impact.
Ndlovu S, Monhemius AJ, 2004, The influence of crystal orientation on the bacterial dissolution of pyrite, Athens, International Biohydrometallurgy Symposium (IBS 2003), Publisher: NUTA, Pages: 409-418
In order to understand the influence of crystallographic orientation on the mechanismof pyrite bioleaching, single crystals cut to expose plane orientations of 100, 111 and 110 were used for the study. Experiments were carried out both in the presence and absence of Thiobacillus ferrooxidans. Experiments to compare the extent of dissolution of the pyrite surfaces in bacterial and sterile solutions under similar solution conditions were also undertaken by matching the conditions in sterile solutions to those in bacterial leaching using an electrolysis cell. Differences in the reaction rates of the pyrite surface planes in both sterile and bacterial solutions have been observed. Furthermore, the results for the comparison between the bacterial and sterile leaching of pyrite samples under similar conditions indicate higher dissolution rates in the presence of bacteria. The microbial corrosion patterns generated on the surfaces were further used to study the leaching process. Microbial leaching of pyrite was observed to create surface corrosion patterns distinct from those of sterile leached samples. In addition the morphology of corrosion patterns arising from microbial leaching were found to slightly differ from one crystal plane to another while those in sterile leaching generally reflected the symmetrical arrangement of the crystallographic planes in the lattice on which they formed. The variation of corrosion patterns observed on the surfaces of bioleached samples seems to indicate a variation in cell-surface interaction from one crystal plane to the other. The results show that the surface properties of mineral sulphides may control the evolution of corrosion patterns and the initial oxidation kinetics in acid bacterial leaching. The overall analysis seems to indicate an influence of the primary cell-mineral interaction during the early leaching stage.Keywords: bacterial attachment, pyrite, crystal orientation, corrosion patterns
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