Search Documents

By S. Banisi, J. Marois, A. R. Laplante

"This paper compares the behaviour of gold and ore in the grinding circuit of Hemlo Gold Ltd. Particular attention is given to grinding kinetics, classification behaviour, and liberation. For grinding kinetics, laboratory grinding of gold flakes and silica, 840-1200 um in size (14/20 mesh), was also performed to provide a standard for comparison and to study in a controlled environment the mechanisms of breakage, folding, smearing and impacting.Grinding kinetics were characterized at laboratory scale with breakage and selection functions. The breakage function showed that 75% of gold disappearing from the 840-1200 um class reported to the 600-840 um; this figure is much higher than for silica ( 46%) or most other minerals, and implies that comparatively fewer fine fragments are produced from the breakage of gold flakes, on account of gold's malleability. The selection function of silica was four times that of gold. At plant scale, the ratio of the selection function of ore and gold increased from 6 for at 50-100 um to 20 at 500-1000 um.Observation of original flakes and their fragments with the scanning electron microscope showed that the main mechanism of ""grinding"" from the 840-1200 um to the 600-840 um class was folding rather than actual breakage. This was confirmed by a measure of individual flake weight. The postulated breakage cycle is that relatively globular flakes become increasingly serrated through grinding; they can then regain their original shape through folding and reflattening into cylindrical and spherical shapes, as the majority does; however, some fragments will at this point undergo actual breakage. Photographic evidence is presented to support the proposed mechanisms.Smearing of gold unto silica was observed when silica was ground after a gold, and embedding of silica into gold flakes when gold was ground after a silica. Both mechanisms occur whenever gold and harder minerals are jointly ground, and result in ""unliberation"" of gold. It is postulated that smearing of gold onto other minerals plays an important role in explaining how gravity recovery can increase overall gold metallurgy, especially when used ahead of flotation.Classification of gold in the primary hydrocyclones takes place at a much finer cut-size than ore, 20 vs. 57 um. This and the slower grinding kinetics result in high gold circulating loads in the primary loop, 6700%, and a gold content in the primary cyclone underflow (PCUF) is twenty four times that of the ore. The gold size distribution for primary cyclone overflow is much finer than that of the ore, although they are essentially similar in the PCUF.Liberation, or more accurately ""gravity recoverability"", was assessed with a 7.5 cm (3"") Knelson concentrator. It varied between the thirties for the primary mill discharge and two cyclone overflows, to highs of 89 to 92% for the PCUF and secondary mill discharge, 89 and 92%, respectfully."

Jan 1, 1991

By J. W. M. Porritt, M. P. Brameld, R. H. McCorkell

"Soil-gas Rn was measured by two types of alpha-particle-track detectors, by emanometry and by counting alpha-activity on Rn-decay-product collectors. Soil samples were analyzed for V by fluorimetric and fission-track methods, their Rn-emanation by decay-product collectors and their total alpha activities with track detectors. The same uranium anomalies were revealed by each method. Fission-track analysis of leaves for V showed only random variations with sampling site, and the Rn emanation of trees and leaves removed from them was barely detectable . The agreement among the other methods is significant, total alpha and collector methods are simple, rapid and useful, and a combination of methods at a site would reveal disequilibrium in the U-decay series if present. Track-Rn measurements are highly reproducible and insensitive to apparatus design and their sensitivity is not enhanced by covering the detectors with thin foil or placing them in large containers.IntroductionIn the past two years , a number of methods of geochemical exploration for uranium have been tested by the authors over the known copper-uranium occurrence at South March, Ontario. This was done partly to compare methods and partly to develop and test new ones. The South march deposit has been described a number of times by others(1,2,3,4). The methods included in this study were the following.Emanometry, Radon in soil gas is measured by pumping the gas into the cell of a scintillation counter or emanometer(5,6). Alpha particles from radon (222Rn) and its decay products (218Po and 214Po) produce scintillations of light in the silver-activated zinc sunphide (ZnS(Ag) covering the walls of the cell. These are counted by a photomultiplier tube and scaler, the count ra sulphide (ZnS(Ag) covering the walls of the cell. These are counted by a photomultiplier tube and scaler, the count rate being proportional to the concentration of radon in the soil gas."

Jan 1, 1981

By Tracy-Lynn Humby

A recent report commissioned by the South African Chamber of Mines, Mining Vision 2030, identifies the South African mining industry?s negative legacy, its exploitation of people and the environment, as the single biggest hurdle to maximizing the industry?s impact on national development. Industry leaders have identified the need to put the past ?to rest?. With reference to three recent cases involving members of the South African mining industry, this paper points to the continuities between the past and present. It argues that the metaphor of ?multiple crossings? is more generative than the notion of putting the past ?to rest? for purposes of engaging with mining?s negative legacy.

Aug 1, 2013

By Serge Ouellet

Identification and quantification of cementitious phases in cemented paste backfill (CPB) is difficult due to the fineness of tailings and the low binder content used in the mixture. Techniques such as X-ray diffraction and thermogravimetry were ineffective (mainly due to tailing mineral interference) to identify and quantify hydration products in most works reported in the literature. On the other hand, scanning electron microscopy (SEM) was used in many cases but mainly for qualitative purposes. This paper presents the development of a new approach based on a computer program (SEM-XMAP) that combines X-ray dot mapping images acquired by SEM and generates a coloured image representing the mineralogy and the microstructure of a given CPB specimen. The technique is applied to one CPB sample mixed with blast furnace slag (BFS) and acidic sulphated mixing water sampled in a mine dewatering system. The technique allowed identifying calcic matrix, unhydrated and partially hydrated BFS particles, and sulphated phases.

May 1, 2007

By Te Gao

It is a general expectancy that in most of the construction and renovation project, the contractor is going to hand over the as-built documents to the owner or the facility management team at the completion of the project. The main challenge for the handover process is to ensure the completeness of the captured building information and the accuracy of it in terms of how well it represents the reality. Building information models (BIMs) can be used as an information repository to store and deliver as-built information. However, due to changes made in the construction and renovation phases and errors made in the design and modeling phases, discrepancies can exist between BIMs created in the design phase (asdesigned BIMs) and actual building conditions. Laser scanning technology is able to efficiently capture accurate geometric information, which provides an opportunity to identify and quantify discrepancies and update as-designed BIMs into as-built BIMs. This paper presents a case study, within which the asdesigned BIM of a newly renovated research lab was updated into an as-built BIM using laser scanned data captured in the renovation phase. This paper introduces the challenges associated with the updating process for the as-designed BIM. In order to address these challenges, this paper introduces a framework that supports the update of an as-designed BIM by incorporating point clouds captured by the progressive laser scans.

Aug 1, 2013

By Robert Lamarre

We will present the summary of a number of case studies whereby mining organizations have succeeded in maximizing equipment uptime by reducing the number of maintenance parts stock outs by more than 80% while scaling down total inventory maintenance parts by more than 20%. We will present a thorough comprehensive methodology to improve business processes in order to optimize inventory management and forecasting. We will examine: ? Demand management optimization ? Forecasting organization ? Inventory management parameters optimization ? Improved replenishment processes ? Inventory optimization and the right KPIs and exception reports We will provide cases in point such as Areva in Africa, Cambior (IAMGOLD) in South America, Osisko Mining Corporation, Barrick Gold/Bousquet Mine and Aurizon Mines Ltd./Casa Berardi in North America. We will discuss how Inventory Management World Best Practices operates in a maintenance environment. We will present how an integrated approach, coupled with a strong Enterprise Asset Management or CMMS system with an Inventory Optimization system specially designed to manage spare parts, actually promises and delivers results.

Nov 1, 2011

By Nicolae Dobritoiu

The literature in this field and the practical activity record that a method, respectively the technology used for an underground mining work have many components which, in order to be applied, demand that for each of the parameters that describe the environment of the mining work and that influence the chosing of that method and that technology of execution, must have values in an interval well determined. There are situations when one or many parameters of the set of parameters that describe the environment of the mining work, can modify its values, and, as a result, one or more components of the methods or technology cannot be applied anymore, making necessary a replacement of their values. The information offered by this graphical-analytical model allow the determination of optimum solutions for the process of digging of the underground mining work and thus it will result the incresing of the technical-economical efficiency of the digging process and, also the increasing of the quality of the underground mining work.

Oct 1, 2009

By Z. Xie

Gas diffusion electrodes (GDEs) for high temperature polymer electrolyte fuel cells (PEFCs) have been prepared using ZrP-modified Nafion ionomer. The performances of these GDEs as cathodes and anodes were evaluated and compared with conventional Nafion ionomer GDEs using Nafion 112 as the PEM under elevated temperature and reduced relative humidity. ZrP-modified Nafion ionomer was incorporated into the catalyst layer to enhance water retention and/or increase the protonic conductivity. The fabrication of ZrP-GDEs was implemented by the ion exchange of Nafion solution with zirconyl chloride, followed by the impregnation of GDEs in H3PO4 solution. The composite electrolytes in the catalyst layer possessed a ZrP content of 20% by weight. GDEs were characterized by TGA, SEM, XRD, and CV. Scanning electron microscopy (SEM) indicated evenly distributed elemental Zr and P within the catalyst layer. Cyclic voltammetry shows a reduced electrochemically-active surface area when the ZrP is incorporated into GDEs. Polarization and impedance analyses indicate the cathode with ZrP-modified Nafion ionomer did not show an enhanced or decreased performance, compared with conventional Nafion ionomer GDEs under elevated temperature and decreased humidity. However, when GDEs with ZrP¬Nafion ionomer were used as the anode, an improved performance was observed. Preliminary experiments show that the anode is more sensitive to dehydration than the cathode under elevated temperature and/or low humidity. Improving the anode water retention capability will help to reduce losses at the anode. However, the incorporation of hygroscopic agents in the cathode catalyst layer is not essential because it is self-humidified by electrochemically-produced water even under elevated operating temperature and lower humidity.

Jan 1, 2005

By Andrew Neale, Len Anderson, Rob Perry

"P.T Freeport Indonesia's new SAG mill commenced operation in February 1995. The reclaim system consists of four apron feeders and a series of three conveyors. The feeders are used in various combinations and relative speeds to blend SAG mill feed. It was recognized during design of the control system that effective automatic control would require dead-time and gain compensation. The successful implementation of the Dahlin algorithm to provide variable dead-time and gain compensation is described and compared to Pl control.RésumeL'opération du nouveau SAG de P.T. Freeport Indonésie a commencé en Février 1995. Le système de réclamation du minerai comprend 4 alimentateurs à tablier et une série de 3 convoyeurs. Les alimentateurs sont utilisés dans une combinaison variée et à des vitesses relatives différentes pour mélanger l'alimentation du SAG. II a été reconnu pendant la conception du système du contrôle que le contrôle automatique demandera une compensation pour le temps de délai et le gain. L'implantation de l'algorithme de Dahlin a été un succès et ii est comparé avec le contrôle Pl.ResumenP.T. Freeport Indonesia inició la operación de un molino semi autogeno (SAG) en febrero de 1995. El mineral es alimentado desde cuatro alimentadores tipo apron feeders y una serie de correas transportadoras. Los alimentadores se utilizan en variadas combinaciones y velocidades para mezclar apropiadamente el mineral que alimenta al molino SAG. Durante el diseño del sistema de control se detectó que el control automático requería de un tiempo muerto y compensaci6n de ganancia. En este documento se describe la implementación del algoritmo de Dahlin, que ha sido exitosa y ha permitido proveer tiempos muertos variables y compensaci6n de ganancia. Ademas se hace una comparaci6n con el Pl de control."

Jan 1, 1996

By Pascal Turcotte

_ Introduction _ LaRonde _ Controlling Instability in Haulage Drifts _ Failure mechanism in drifts walls _ Failure mechanism in drifts back _ Field Behaviour of Support Elements _ The ?Hybrid Bolt? _ Conclusions

Feb 1, 2008

By Filipe Beretta

This study investigates geophysical logging capacity to predict coal quality. It was analyzed for possible correlation, some parameters determined via laboratory analysis of coal against results for the same parameter derived from wireline logs recorded by a geophysical probe. These probes detect variations in some rock physical properties, such as their natural gamma ray emissions and electrical resistivity. Results showed a strong correlation between natural gamma and ash content, establishing a linear model to estimate ash content from geophysical logging data with a low estimation error (less than 5%). Besides, results showed that there is no correlation between sulphur content or volatile matter and resistivity, neither with natural gamma of the rocks. Ash content derived from gamma ray values can be used as secondary information to evaluate coal quality during resources estimation, using methods such as soft indicator kriging. The methodology is illustrated using a case study at a coal deposit in south of Brazil.

Oct 1, 2009

By G. R. Dunning, M. R. Wilson

"Abstract - The early Paleozoic accretionary tectonic regime that was established along the Laurentian margin of the Newfoundland Appalachians provided a favorable setting for shear-hosted gold mineralization along a major terrane suture, the Baie Verte-Brompton Line. The Stog’er Tight prospect is one of several mesothermal-style gold occurrences hosted by shear zones within accreted ophiolites and oceanic arc terranes on the Baie Verte Peninsula. It is an epigenetic, stratabound deposit that is confined to shallow-level gabbro sills within the volcanic cover sequence of the allochthonous Point Rousse ophiolite complex. Gold mineralization at Stog’er Tight is associated with hydrothermal mineral assemblages represented by chlorite-calcite, sericite-ankerite, red albitepyrite (±Au) and chlorite-magnetite alteration zones. Gold occurs with pyrite within the intensely altered gabbro, along the margins of syn- to late-shear, quartz-rich, replacement veins.The Stog’er Tight gabbro served as a rigid body conducive to shear deformation and fluid penetration, whereas, its high Fe-Ti oxide content induced fluid oxidation and gold-pyrite precipitation. Hydrothermal alteration involved progressive CO2, S, Na, and LILE metasomatism, along with significant enrichments in the REE, HFSE, and Th in the high-grade ore zone. Temperatures of vein formation and alteration are constrained by oxygen isotope thermometry to be between 250°C and 480°C. Isotopic compositions of vein quartz from the Stog’er Tight prospect are uniform (??O = +12.5 ± 1‰) and fall within the range cited for many shear-hosted, auriferous quartz veins.A U-Pb zircon igneous age of 483 +3/-2 Ma for the Stog’er Tight gabbro is consistent with its stratigraphic correlation with other Ordovician ophiolitic and volcanic arc/back-arc assemblages in Newfoundland. The U-Pb age of a rare variety of hydrothermal zircon recovered from the high-grade ore zone directly constrains the timing of gold mineralization to 420 ±5 Ma, in accord with a major orogenic episode of Silurian age that produced many of the magmatic and metamorphic rock suites in north-central Newfoundland. Our results are consistent with a post-peak metamorphic, late-magmatic model for gold mineralization that occurred during the waning stages of Silurian orogenesis, driven by emplacement of I-type granitoid intrusions into the crust."

Jan 1, 2000

By Changping Hu, Keqin Tan

In 1937, the Metallurgical Department of the National Resources Committee established a copper refinery plant (predecessor of the Chongqing Smelter) in Changsha, Hunan Province, China. The blister copper produced by a local copper smelter was casted as anode for electrorefining. The plant, with a capacity of one ton of electrolytic copper per day, was designed and tested in 1937. At the trial production stage, a total of 9 tons of cathode copper was produced. The plant was formally put into operation in July 1938. In the same month, more than 20 tons of electrolytic copper with purity over 99.9%Cu was produced. This was the first batch of electrolytic copper produced in China. In 1939, China’s largest non-ferrous metal smelting plant, Fengtian Gold Mine Refining (predecessor of the Shenyang smelter) was completed and put into operation in Shenyang, mainly producing nonferrous metals such as gold and silver, as well as copper and lead. In 1939, the Kunming copper smelter (predecessor of Yunnan Smelter) was completed and put into operation. The plant equipment, imported from the United Kingdom, was designed to produce 1,200 tons of electrolytic copper annually. In 1943, Jiatong smelter (predecessor of the Shanghai Smelter) became the 4th domestic cathode copper producer. Since 1949, China has gradually established a large copper industry. These developments are discussed in this paper. Today, China operates nine out of the twenty largest copper refineries in the world. With a total capacity approaching 9 million tons of copper per year, China has the world’s largest copper refining capacity. INTRODUCTION China is a country with a long history of copper mining. The earliest smelter in China in recent times was the Shanghai Smelter, which was built in 1912. From then until 1949, China successively built Chongqing Smelter, Kunming Smelter and Shenyang Smelter. The world's first copper electrorefinery was the Pembrey refinery built in the UK in 1869 (Lu, 1999). However, it was not until 69 years later that the technology was spread to Changsha, China.

Jan 1, 2019

Cobalt mostly occurs as a minor, but valuable, constituent in most nickel and a few copper ores, however it is not generally found alone in commercially viable deposits. Its concentration and extraction are therefore intimately linked to the recovery of the primary metals and the major task for the metallurgist is to extract cobalt of commercial grade from a much larger mass of either nickel or copper and sometimes both. With a particular focus on Vale Inco?s operations, this paper provides a brief overview of the mineralogy of the main deposits being currently exploited that contain cobalt as a co or by-product. The concentration and then extraction to metal are reviewed and some advances released into the public domain are discussed.

May 1, 2009

By M. R. Saharan

A brief overview of rockburst control measures is presented. The paper then elaborates on one key rockburst control measure, which is known as destress blasting. A historical background of the technique is presented in order to understand different aspects of its field application. The publication enumerates key aspects of the technique as being used in practice in South Africa and North America. The paper also presents an analysis of three case studies in order to demonstrate difficulties associated with the field application of distress blasting in hard rock mines.

Jan 1, 2006

By Sean McClenaghan

Significance Setting Size Production Value History of Discovery Zn and Pb at Austin Brook Brunswick Belt Exploration Discovery Hole Geology Structure Metal Zonation Directed Research Incremental Ores Precious metals Closure and Beyond Mining Remnants Tailings

May 1, 2013

By L. E. Young

"The Red Dog deposit of the western Brooks Range, Alaska was discovered in the 1970s. Two mineralized areas are present, the Main and Hilltop deposits. With indicated and inferred reserves of 77 million tonnes of 17.1% zinc, 5.0% lead and 82 g/ tonne silver, the Main deposit of Red Dog represents one of the world's largest zinc-lead deposit s. Since serious evaluation by Cominco commenced in 1980, a better understanding of deposit geology has been gained through 10 715m of diamond drilling and concurrent geologic, geophysical and geotechnical studies. The Red Dog deposit is of Mississippian to Pennsylvanian or Early Permian age, and straddles a redox transition in fine-grained and chemical sediments of the Red Dog structural sequence.The Main deposit has been modified by regional Mesozoic thrust faulting and isoclinal folding, resulting in complex interrelationships between silica rock, sulphide rock and barite. Multiple lines of evidence suggest the Main deposit contains both a syngenetic stratiform and a replacement component. Ore fluids were probably derived by regional lateral movement of brines through a coarse clastic footwall aquifer, then upwards along block faults to the site of the Red Dog deposit.Historical PerspectiveThe region in the vicinity of the Red Dog deposit (Fig. 1) was first prospected by J. W. Kelley in the late 1880s (Orth, 1967). The first coordinated inland exploration was conducted by the U.S. Geological Survey in 1910-1911 and 1923-1926 (Smith, 1913; Smith and Mertie, 1930). The earliest reports of zinc-lead mineralization in the region include reference to samples collected at unknown locales by Eskimo prospectors (Anderson, 1944). In 1955 stratiform pyrite was discovered 19 km west of Red Dog by I.L. Tailleur of the U.S. Geological Survey (Tailleur, 1970). The first reported visit to what is known as Red Dog was by I.L. Tailleur in 1968, who was field checking a colour anomaly noted by B. Baker, a local bush pilot (Tailleur, 1970; Moore et al., 1986) ."

Jan 1, 1989

By Matthew A. Baumann

Tooth-wear on mining shovels requires continuous monitoring. Worn teeth impede excavation performance, increase energy usage, and increase the risk of lost or broken teeth and adapters. A machine-vision-based automated tooth-wear monitoring system is presented. The system employs a rugged boom or stick-mounted camera to capture images of the shovel teeth. An onboard computer processes the images in real-time to determine the length of each tooth. The current wear state is available via a network-accessible log for on-demand status updates. By continuously recording tooth length changes over time, the logs can be used to estimate wear rates and patterns, permitting comparisons between different G.E.T. configurations, operator behaviour patterns, or material types. This detailed, quantitative data permits site-specific optimizations to wear packages and maintenance scheduling. Automating wear monitoring offers the crucial wear information necessary to minimize maintenance costs and reduce unscheduled downtime. A 37-day field trial in a copper-gold mine demonstrated the ability of the system to measure tooth lengths, compute wear rates, and detect differences in tooth wear based on their position on the bucket.

Nov 1, 2011

By George C. Riley

While the general public has little knowledge or appreciation of either the mining or explosives industries, modern civilization could not exist without them. They are to-day the key industries of the world. In common with many other industries the demands of the war greatly stimulated the production of explosives and the research necessary for such increased production. Production, supplies of all kinds, munitions of all sorts and then again production, practically regardless of cost, were the first reactions to the imperative war demands of the governments of the world. Following the war there was a momentary lull, then first gradually but with quickening acceleration, particularly in a recent slump, the situation was reversed - cost and not production was the dominant factor. Some industries readjusted themselves very rapidly and completely. Others were but partially re-adjusted and others again only carried out the process of deflation in certain departments. The explosives industry in Canada has not only thoroughly deflated itself, but has learned to apply to commercial disruptive explosives, the best, most efficient and most economical methods of manufacturing developed during the war. As a consequence, miners have at their disposal to-day better and more different kinds of compressed energy than ever before in all the long history of mining.

Jan 1, 1925

By J. H. Bernard, K. Žák

The three traditional types of Variscan vein Pb-Zn-(Ag) mineralization recognized in the Bohemian massif from historic paragenetic studies are confinned by modem metallogenic studies. Stable C, S, and O isotope data, as well as Pb and Sr isotopic ratios of the deposits, indicate a predominantly crustal origin of the constituents in all three types. Although the data also suggest differences in temperature and pressure of formation, and the oxidation conditions and nature of the hydrothermal fluids, nonetheless they are consistent with prevailing metallogenic classifications of the vein mineralization

Jan 1, 1992