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By J. J. Jonas

The categories of interpass time encountered in hot rolling are characterized. These are shown to fall into three broad categories: short (in rod rolling); intermediate (in strip processing); and long (in plate schedules). The effects of interpass time on recrystallization and carbonitride precipitation are described, and particularly on the interaction between these two mechanisms. The interactions, in turn, determine the final microstructure produced as well as the mechanical properties.

Jan 1, 2005

By Leslie S. Weldon

THE Lake Shore mine has been developed by two vertical shafts, with level intervals at 200 feet to the 2200 level and at 125 feet below this horizon. A main cross-cut joins the two shafts on all levels to the bottom of No. 3 shaft, and opening into these cross-cuts are the ore passes and sand passes, which are completed from surface To the 4450 level. In the west part of the mine, additional connections have been made between No. 1 and No. 2 veins, through which the major part of the ore from No. 2 vein west is routed to drifts in No. 1 vein. With the lesser amount of stoping on No. 1 vein, this arrangement permits better haulage to be maintained. The ore passes are driven at 50 degrees from the ends of short cross-cuts off the main ones and are broken through to the levels above at the mouths of the short cross-cuts, to allow for dumping on each level. The passes are controlled at each level by ball-and-chain gates and deliver to crushers and thence to loading pockets, shown in Figure 1. That system is quite flexible in that it is possible to by-pass the crushers at any station and load from either shaft at a number of different pockets. The sand passes are driven from the main cross-cuts at the same inclination as, and parallel to, the ore passes. Each is equipped with a chute and dump hole, so that waste or sand fill may be loaded or dumped at each level. A transfer door, hinged on the bottom, is installed opposite the chute for by-passing fill from one level to the next, and in the closed position protects the opening at the top of the pass. The dump hole situated beside the transfer door is protected by a grizzly with 10-inch spaces. Waste rock may be withdrawn from the system through No. 3 shaft loading pocket at the 2950 level to a waste bin on surface. Levels are developed by drifts in No. 1 and No. 2 veins for their entire lengths. Subsidiary breaks are followed at a later date, when full information has been obtained by exploration, and a considerable amount of development by sub-drifts is carried out in the upper part of the mine, particularly in more or less erratic sections of No. 1 vein.

Jan 1, 1936

By A. Hutwalker, T. Plett

"Blast fumes are one of the major sources for NOx in underground mines. In 2016, the Occupational Exposure Limits for NOx in Germany were reduced by 90%. The task is to keep re-entry times after blasting at the present level and thereby ensure an economic operation of the mine. Measurements show that using ventilation solely is not sufficient. A new approach to reduce NOx from blast fumes is described. Laboratory experiments were performed and a reduction of NOx was observed. Measurements were conducted at an explosive factory’s testing facility and in an underground mine at blasting operations. INTRODUCTION Whether for production of ore or for drift development, the processes in an underground mine are always the same: 1) fracturing the rock, 2) loading the pile, 3) support the resulting cavity. The fracturing of the rock can be done mechanically, by cutting, for example by using continuous miners or tunnel boring machines, or by drilling and blasting. Drilling and blasting is more flexible than mechanical driving, as it can be used independently of the rock strength. Furthermore, this driving method allows a more flexible reaction to changes in geological and/or operational conditions. Thus, underground mining and blasting are almost inextricably linked with each other, and regardless of the size and level of technology of the mine, blasting is hardly avoidable. Depending on the mining method chosen and the existing framework conditions, such as the mechanical properties of the rock or the availability of machinery, blasting is an integral part of daily operations. Even in mines where blasting is not part of regular operations, it cannot be completely avoided. The blast fumes generated by the explosions are, in addition to diesel engine emissions, one of the two main sources of emissions of nitrous gases underground. Up to now, state of the art for dealing with blast fumes is ventilation. The fumes are diluted with fresh air and ventilated out of the mine. This treatment of blast fumes is more than sufficient with the former German Occupational Exposure Limits (OEL). The adaption of the OEL in Germany to the recommendations of the Committee on Occupational Exposure Limits (SCOEL), a committee of the European Commission, leads to big challenges for the mining industry in reducing the concentrations of these gases at the workplaces underground. On its meeting on May 2nd and 3rd 2016, the Committee on Hazardous Substances (Ausschuss für Gefahrstoffe, AGS), an advisory body of the German Federal Ministry of Labour and Social Affairs (BMAS), advised the BMAS to copy the OEL, as recommended by the SCOEL, to the Technical Rules for Hazardous Substances (TRGS 900). BMAS followed this advice, consequently the new OEL where published on November 4th 2016 and became part of the TRGS 900. Table 1 shows the former and new OEL for Germany. These new OEL became law after publishing, but two exceptions were made: For tunneling operations, they became law on October 31st 2017, for mining operations they will become law on October 31st 2021 (BAuA, 2004, 2016, 2017)."

Jan 1, 2019

By B. I. Whittington

This paper examines the effect of cation type (i.e. NH4+, Na+ and K+) and anion type (i.e. SO42- and C1-) on the extraction of nickel during the pressure acid leaching of a Western Australian laterite ore. The results are compared with testwork conducted with other Western Australian nickel laterite ores and the possible process implications of adding an additive to a plant autoclave are considered. Addition of either (NH4)2SO4, Na2SO4 or K2SO4 increased both the nickel extraction and the acid consumption, provided that the level of additive was not too great. For example, the nickel extraction of 93% increased to above 96% in the presence of additives, but decreased to 94% when, for example, NH4 levels increased from 7 kg/t ore to 21 kg/t ore. The relative stability of the jarosite species formed when additives were present influenced the amount of jarosite in the residue and, hence, both the final free acidity and overall nickel extraction. The use of Cl- versus SO42- salts as additives had little effect on overall nickel extraction or overall free acid values, although the presence of SO42- additives appeared to enhance nickel extraction kinetics over the first 60 minutes of the reaction. In contrast, manganese extraction was enhanced by the presence of Cl- additives.

Jan 1, 2004

By H. A. Pearse

The history of the flotation process, as applied to the practical field of ore dressing, dates back somewhat less than twenty years; yet this fact may be overlooked in view of the present universal dependence on this process in the concentration of almost all classes of ore. It is therefore interesting to recall that Britannia was the scene of some of the earliest experiments with flotation on a commercial scale. In 1911, sixteen years ago, an Elmore vacuum machine was operated for several months with encouraging results. In 1913, some time before flotation was very generally adopted elsewhere, a Minerals Separation plant, capable of treating 600 tons daily, was operating successfully at Britannia. Considering how little was known of the theory and practice of flotation at that time, the recovery was remarkably good, but it was not until the present mill was completed in 1923 that any attempt was made to raise the concentrate grade by differential flotation, or, in other words, to float the chalcopyrite while rejecting the then worthless pyrite with the tailings. The first ore passed through the present concentrator in March, 1923. As originally designed, the rated capacity was for 2,000-2,500 tons, but this has been increased year by year, until at the present time 4,000 tons daily can be treated economically. During the first few months of operation the concentrate grade averaged only 10-11 per cent Cu, but by the end of 1923 this had been raised to over 20 per cent, due to the elimination of the pyrite by differential flotation. In 1923 the tailings averaged approximately 0.25 per cent Cu, but also in the matter of recovery a considerable improvement has been effected, for during the year 1926 an average tailing of 0.15 per cent Cu was maintained.

Jan 1, 1927

By G. A. Fenton, A. Vervoort, M. Alvarez Grima

"High-risk underwater mining operations necessitate characterizing spatial heterogeneity and resource uncertainty. Local average subdivision is a method of simulating spatial deposit variability inside a cell through a sequence of discretization stages, during which a cell is further subdivided into four or eight cells. New developments are presented to validate simulated deposit models and deal with point measurements of geotechnical and ore-grade properties. This paper illustrates the relevance of translating spatial deposit variability into financial or operational performance indicators during underwater resource exploitation. Two synthetic case studies highlight the challenges of underwater mining in relation to production plans and equipment selection.RÉSUMÉ Les opérations d’extraction minière subaquatique à risque élevé exigent une caractérisation de l’hétérogénéité spatiale et de l’incertitude de la ressource. La moyenne locale de subdivision est une méthode de simuler la variabilité spatiale du gisement dans une cellule par une séquence d’étapes de discrétisation durant lesquelles une cellule est subdivisée en quatre ou huit cellules. De nouveaux développements sont présentés afin de valider les modèles de simulation des gisements et de traiter des mesures ponctuelles des propriétés géotechniques et de teneur du minerai. Le présent article illustre la pertinence de traduire la variabilité spatiale du gisement en indicateurs de rendement financier ou opérationnel durant l’exploitation subaquatique de la ressource. Deux cas synthétiques soulignent les défis de l’exploitation minière subaquatique par rapport aux plans de production et de choix des équipements."

Jan 1, 2015

By J. Kempken, R. Hagmann, C. -P. Reip, W. Hennig

The CSP technology symbolizes a highly productive process for the cost-effective production of steel grades with a range of sophisticated properties comprising both the inner quality of hot strip, its surface formation as well as the relating technological characteristics. Thanks to extensive development work undertaken during the last 15 years, the range of steel grades that can be produced was continuously expanded and the process technology optimized. The present paper describes the ongoing development work concerning the production of higher-strength, microalloyed pipe steels. The resulting hot strip, due to the associated thickness and the potential pipe diameters, is particularly suited for being processed to HFI-welded pipes. Based both on ferrite-pearlite as well as very fine-grained, ferrite-bainite hot-strip microstructures, strength levels of up to grade API X80 can be realized. It can be demonstrated that hot strip produced in a CSP plant has very good toughness values at temperatures down to -60°C and can even make application with required sour-gas resistance possible.

Jan 1, 2005

By J. D. Bosman, L. J. Gardner

"The Bushveld Complex is a large layered igneous intrusion, located in the northern parts of the Republic of South Africa. The complex hosts the largest known reserves of Platinum Group Metals in the world. On the western limb of the complex, mining of the Merensky economic horizon and UG2 chromitite layer has been conducted for many years by several mining companies, including Impala Platinum Limited. Over the past decade, Impala has planned a new generation of greenfield vertical shafts, commencing with comprehensive geological and geotechnical studies. As part of the geotechnical studies, numerous tests have been conducted to quantify the mechanical properties of the various near-reef rock types. These tests include point load tests conducted in the field, as well as uni-axial compressive strength, triaxial compressive strength, and Brazilian disc tensile strength tests conducted in specialist laboratories. The authors have compiled an extensive database containing a large number of tests for different rock types, ranging from felsic Anorthosite to mafic Pegmatoid. The database was analysed to quantify the mechanical properties and values for Mohr Coulomb and Hoek Brown failure criteria for each rock type typically exposed by mining. The paper will provide a data set of rock mechanical properties typically used in numerical modelling and other design processes. Using the significant number of tests available, data describing the variability of the various parameters will be included."

Jan 1, 2015

By I. Filzwieser, M. B. Hanel, A. Filzwieser

The paper describes the current density increase within the last 150 years. From the beginning in 1885 at 30 A/m² up to the highest used current densities nowadays at 420 A/m² towards future pathways were even 1000 A/m² can be achievable. A short tour through history will highlight the milestones of the process of electrolytic refining of copper. Besides the improvement of the existing technology, the biggest changes leading to higher possible current densities are linked to the introduction of the ISA stainless steel plates and the introduction of the parallel flow principle. Furthermore, the parameters influencing the limitations regarding current density and therefore the practical used current density as well as the influence from the chemical composition of the electrolyte is discussed. Finally, the possibility of further increasing the current densities by enhancing the relative movement between electrolyte and electrode will give an outlook about the future of the copper electrolysis process. INTRODUCTION The current density is the most important characteristic to describe the productivity of a copper refining electrolysis besides the characteristic number for the electrical efficiency. Over the last 150 years, current density has risen from a few amperes per square meter to over 400 A/m² without any significant change in the principle of electrolytic refining. This increase in current density is documented exemplary by the electrolysis of Montanwerke Brixlegg in Austria (Brixlegg, 1963, 2013). The very beginning of the technology of electrolytic refining of copper was first patented in England by James Elkington in 1865 and the first electrolytic copper refinery was built in Newark, New Jersey, in 1883 (Armstrong, 1999). The secondary smelter Montanwerke Brixlegg, Austria, has been operating an electrolysis plant since 1884. In 1988, the third "Mount Isa" electrolysis plant worldwide and the first in Europe was put into operation in Brixlegg. Since 2010, the so-called high-current electrolysis (parallel flow METTOP-BRX Technology) with a current density of approx. 400 A/m² has been operated in half of the electrolysis process.

Jan 1, 2019

By R. A. Ford

The paper outlines: methods used for the determination of wear metals in motor and transmission oils; contaminents in motor, transmission and crusher lubricating oils; and viscosity determinations. Case histories and costs are presented to illustrate the value of an oil analysis program. Introduction NORANDA MINES LIMITED (BELL COPPER DIVISION) is located on the shores of Babine Lake, approximately 450 miles north of Vancouver, British Columbia. Access to the mine is by road from Topley, B.C., about 40 miles away. When a preventive maintenance analysis program was first considered, it was obvious that if samples were to be sent out for analysis, results would not be available for at least a week, due to the distance from any commercial laboratory. The assay laboratory was asked to investigate the possibility of determining wear metals on site. A limited program was started soon after production commenced, and this has now grown to include all large mobile equipment as well as crushers and grinding mills. The laboratory also now determines viscosity, fuel dilution, dirt and abrasives, glycol and water. All these results are ready within two days. This paper will outline the methods used, data interpretation, several case histories and the benefits from such a program.

Jan 1, 1977

In this study, we develop a detailed model of the likely future carbon footprint of primary copper supply. We develop a peak copper production model, based on a detailed copper resource data set, and combine this with a comprehensive life cycle assessment model of copper mining and milling to predict greenhouse gas emission rates and intensities of Australian and global copper production up to 2100. By establishing a quantitative prediction of both copper production and corresponding greenhouse gas emissions of Australian and global copper industry, we then analysed the emissions intensity of various energy input scenarios, such as business-as-usual, solar thermal electricity and solar thermal electricity with biodiesel. The Australian Government has an aspirational goal for long-term greenhouse gas emissions of an 80% reduction from the 2000 level by 2050. For the copper sector, this means moving from about 12.6 Mt CO2e in 2000 to a goal of some 2.52 Mt CO2e in 2050 (assuming equal emissions reductions across the economy). Based on the energy sources modelled, only the solar thermal plus biodiesel scenario was capable of achieving this goal at about 0.15 Mt CO2e, since the solar thermal alone scenario still includes normal petro-diesel as a major source of emissions. Overall, it is clear that there are abundant resources which can meet expected long-term copper demands, the critical issue is more the carbon (and environmental) footprint of different copper supplies and use rather than how much is available for mining. It is clear that the switch to renewable energy can have a profound impact on the carbon intensity of copper supply, even allowing for increased energy intensity as ore grades decline, and a complete conversion to renewable energy will position the copper sector to meet existing annual greenhouse gas emissions targets and goals.

Aug 1, 2013

By Alan Bauer

IN RECENT PAST YEARS, the mining industry has expanded rapidly and mining engineers have not been generated in sufficient numbers to sustain this growth. Canada has not been alone with this problem, which has resulted in considerable soul-searching as to what the solution might be. Because of the unfavourable economics of running small departments such as mining, metallurgy, ceramic engineering, etc., one approach in some cases has been to put these departments together to form a department of mineral science which now has a broader base structure. Another solution has been the "conversion kit" program which has been conducted both at universities and in industry. At universities, such programs have consisted of converting graduates of other engineering disciplines into mining engineers. In some of the large mining corporations, extensive training programs have been used with the same aim.

Jan 1, 1972

By S. E. Jackson, L. J. Cabri

Quantitative determination of gold at sub-ppm concentrations in sulphide minerals is an important component of deportment studies for sulphide-gold deposits. Laser Ablation Inductively Coupled Mass Spectrometry (LA-ICP-MS) analysis is preferred for this application because it rapidly and cost-effectively provides spatially resolved (<20 pm), low ppb concentration data for gold and other elements in mineral grains. Recent advances in LA-ICP-MS analysis include the development and application of elemental mapping. Raw signals from multiple line scans or lines-of-spots are deconvoluted and calibrated to generate elemental maps which provide detailed information on spatial variations of gold and other elements within and between grains.

Jan 1, 2011

By J. J. Denny

IN November, 1932, an investigation of silicosis was undertaken at the Mcintyre Porcupine mine, Schumacher, Ont., after a discussion of the p"roblem with Sir Frederick Banting and his staff. As a result, it was decided to carry on dusting experiments with animals at the mine in a manner that would duplicate as far as possible actual industrial conditions. At that time 50 guinea pigs were placed in the crusher house tunnel of the mill where a considerable quantity of fine dust, containing approximately 35 per cent of free silica, was being constantly produced. These animals lived in this atmosphere for periods up to one year, and, while on autopsy large amounts of dust were found in the lungs, not a single case of silicosis had developed. These negative results suggested, among other things, that the mine gases might be a predisposing factor in the production of silicosis, and the results of this investigation (1) led us to undertake the study of the hydrogen-ion concentration of the condensate of the atmosphere, both in the mine and in various sections of the mill. The CO, combining power of blood serum on a series of 400 miners was also studied at this time. While these results were inconclusive, the variation in the hydrogen-ion concentration of the condensate between the surface and underground atmospheres encouraged us to investigate the effect of neutral, weak acid, and alkaline solutions on the solubility of siliceous materials. Gye and Purdy (2) were the first to point out that the chemical reaction, and not the physical presence of siliceous material, was responsible for the production of the fibrosis in silicosis. This work was investigated by Gardner and Cummings (3), who showed that the tissue reaction to quartz was definitely proportional to the size of the particle. They found that 1-3 micron particles of quartz produced an acute proliferative fibrotic response, while the 10-12 micron particles produced only a foreign-body reaction up to a period of three years. It is accepted that the dangerous silica particles retained by the lung are under 5 microns in diameter.

Jan 1, 1937

By W. Griffith

"While oxalic acid precipitation practices are commonly applied on purified rare earth elements (REEs) pregnant leaching solutions (PLS), few efforts have been reported using oxalic acid (OXA) to recover REEs directly from untreated PLS. High oxalic acid demand is the most significant issue in all these direct oxalic precipitation (DOP) practices. Preliminary research on DOP of REE from a dilute PLS originating from an acid bake followed by water leaching was conducted. At 75°C, the oxalic acid demand was between 12 and 18 times the stoichiometric requirement for complete REE precipitation. Conducting DOP at 25°C had superior REE recovery but the product purity and filterability declined. Between 75°C and 100°C, REE recovery increased with increasing temperature. When sodium hydroxide was used to adjust the pH during DOP, in the range of 0.5 to 1.5, higher pH benefited REE recovery. Using ammonium hydroxide in place of sodium hydroxide, the REE recovery was reduced by close to 5%. Sodium chloride addition to the PLS was also investigated and the results showed that at both 75°C and 25°C, the REE recovery was enhanced substantially. At 25°C, when the oxalic acid addition was controlled at 4.7 times the stoichiometric requirement, the overall REE recovery reached 95% with the addition of 240 g/L NaCl. Other reagents such as KCl, NH4Cl also showed significant enhanced REE recovery at the same oxalic acid addition. The addition of sodium sulphate appeared to largely enhance the precipitation of LREE but inhibited the formation of HREE oxalate. All results indicate the formation of rare earth double salts may play an important role in REE DOP sulphate media.INTRODUCTIONThe conventional routes for recovering rare earth elements (REEs) from a sulphuric acid pregnant leaching solution (PLS) involves an initial purification step for removal of iron, aluminium for example by precipitation through neutralization, followed by precipitation of REEs as hydroxide, oxalate or carbonate salts, or by bulk solvent extraction for REE recovery (Xia, 2013). Another route was used by Bayan Obo in their historical flowsheet, where the PLS was first subjected to double sulphate precipitation, then the remaining REEs, mostly heavy rare earth elements (HREE), were recovered by oxalate precipitation (Li, 2011)."

Jan 1, 2016

By S. Kashani-Nejad

The formation of oxides during the dehydration of MgC12,6H20, Bischofite, was studied by heating the bischofite over a range of time and temperatures in ambient atmosphere. Using a methanol-leaching technique developed by authors, the oxides that formed were isolated, identified and assayed. Three distinct regions of oxide stability were identified. The oxide produced at dehydration temperatures less than 300 °C was Mg2(OH)3C1,2H2O; at 300 °C, mixtures of MgOHC1 and Mg2(OH)3C1.2H2O were formed and at 400 °C, MgOHC1 was the only oxide produced. The presence of MgO observed in the products of the dehydration of bischofite at temperatures above 400 °C was due to the thermal decomposition of the MgOHC1 that was formed while the sample was heating to over 400 °C.

Jan 1, 2006

By Dave M. Jakelski, Gerhard W. Heinrich, Peter F. Wells, Daniel F. Suarez, Jamie B. Beauchamp

"A need for increased copper concentrate production and for less nickel contamination in that concentrate at Falconbridge's Strathcona Concentrator during 1993 required the installation of a third flotation column and improvements in the operation of the existing circuit. Innovations in wash water distributor and launder design were fundamental in achieving objectives on a new 3 meter diameter column. Minnovex plug-type spargers were tested on a 2.1 meter diameter column in order to reduce maintenance requirements. The paper details the measures taken to enhance column flotation circuit performance and the results obtained.IntroductionFalconbridge's Strathcona Mill receives 10% of the ore feed from a rich copper zone in the Strathcona mine. This ore typically grades 7% copper and 1 % nickel and, because of its high copper content, it is processed in a separate circuit ('C' circuit) which consists of conventional grinding, rougher flotation with the concentrate being treated with lime to pH 12.3 and cyanide followed by column flotation. The columns are operated with mechanical flotation scavengers and the scavenger concentrate is returned to the column feed. Testwork conducted in 1991 showed that the original flotation column (Column 2) could only produce 5.5 mtph of concentrate with less than 0.5% nickel (Figure 1).Between 1991 and spring of 1993, production was increased at times by open circuiting the scavengers. Metallurgical improvements were obtained by improving the wash water distributor of Column 2 and by wash water sprays in conventional cells (1 ). However, the scavenger concentrate assayed 0. 7 -0.8% nickel and was not acceptable for long term operation. When Copper ore production targets were significantly increased for 1993, it became clear that an additional flotation column was required. The new flowsheet employs mechanical scavenger cells on the column tails as in Column 2 circuit (Figure 2). A -parallel configuration was chosen as pulp solids fraction has been shown to be a critical variable and the second column in series would receive a lower density feed."

Jan 1, 1994

By Ross Gallinger

In 1997 a group of Canadian mining companies met to review the Mine Environment Neutral Drainage (MEND) program and to consider future activities. They concluded (i) that Canadian industry and NRCan should fund a small secretariat in Ottawa to support technology transfer in Canada and (ii) that it was important for industry to continue the momentum of MEND on an international scale. The need for INAP (International Network for Acid Prevention) was strongly endorsed by company, university, consultant and government experts from Australia, Canada and the U.S. who were convened in Vancouver in February 1998. The initial focus was the development of a solid knowledge base covering the collective experience of INAP&apos;s members to promote the dissemination of successful practices, the identification of knowledge gaps and the formulation of effective research proposals. The sharing of information on past successes and failures alone was viewed as sufficient justification for the formation of INAP. INAP was officially launched in October 1998, and is now an effective, industry based initiative to globally coordinate research and development in the management of sulfide mine waste. Significant improvements in the management of sulfidic mine materials through knowledge sharing, research and development of technology by INAP will reduce liability associated with acid drainage. This paper will explore the international efforts and activities of INAP.

May 1, 2002

By \/eena Sahajwalla, Jonathan Dicker, Paul O'Kane, Cath Skidmore, James Dankwah, Magdalena Zaharia, Rita Khanna, David Knights, N Saha-Chaudhury, Somyote Kongkarat

Due to the inherent limitations of current methods of disposal of end of life polymeric materials, avenues are researched towards developing alternative, environmentally friendly and economic recycling processes. Different polymeric materials (i.e. rubber, high density polyethylene (HDPE) and polyethylene therephtalate (PET)), quite distinct in terms of chemical structure and composition, were considered in the present study as carbon resources in EAF steelmaking. Investigations were conducted in both laboratory and industrial scale steelmaking to assess the effectiveness of using these materials as carbon sources for slag foaming in EAF steelmaking. Slag foaming is important because it enhances furnace efficiency.

Jan 1, 2011

By A. Allaire, J. Torrealba-Vargas, R. Welyhorsky

Early testwork was carried out to select the plant process design criteria and flowsheet selection. Additional testwork was carried out during the feasibility study to support the optimization of the plant design criteria. The test results showed that the recovery of gold was not very sensitive to grind size in the range of 75 to 105 microns. An additional result was that the presence of lead nitrate did not improve the kinetics of gold leaching. This conclusion was supported by the low content of sulphides in the ore. It was also found that the presence of lead nitrate increased copper dissolution, producing the potential for an increase of copper reporting to electrowinning, which is detrimental to the overall gold recovery process. The use of oxygen in leaching was investigated to increase leach kinetics. The results of leaching tests to compare using oxygen instead of air indicated that, due to the improved leach time, it was possible to reduce the number of leaching tanks from twenty four (24) to twenty (20).

Jan 1, 2011