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By H. L. Cheng, C. H. B. Leitch, C. T. Hood, A. J. Sinclair

"Epithermal Zn-Pb-Cu-Ag-Au quartz-carbonate-barite veins at the Silver Queen mine near Owen Lake, west-central British Columbia, are hosted by Late Cretaceous Tip Top Hill andesitic volcanic rocks. The veins form a rectilinear northwest-northeast pattern that differs slightly from regional structural trends. The main northwest-trending veins are oriented very close to the trend of regional northwest faults, but the crossing veins tend to be more east-north-easterly (070 degrees)compared to a regional north-easterly trend (040 degrees). The character of the veins suggests they are extensional features formed by dextral slip related to Paleogene oblique subduction, or intrusion of magma at depth, or both.In detailed exploration at the mine, the veins cannot be modelled as simple tabular sheet-like bodies. Instead, they are complex structures that divide and rejoin, forming multiple veins or stringers, or are found in shear zones as replacement features with quartzsericite- clay-carbonate-pyrite alteration haloes of variable width that make definition of vein margins and correlation from hole to hole ambiguous. In addition, individual veins within each of the main structures have en echelon characterboth along strike and down dip.Geological and assay data must be carefully studied to define the margins of these complex veins before any estimation of ore reserves may be made. Where multiple veins occur in a section, ore/gangue mineralogy, assays, character of wallrock alteration, and thickness of vein and mineralized hangingwall, median and footwall zones must be used to evaluate continuity of mineralized structures. Well-defined sections are projected into areas of increasing complexity. Once the vein boundaries are defined, metal concentrations, important metal ratios(Au/Ag, Pb/Zn, Cu/Zn), and true thicknesses of the vein provide the basic data for reliable ore reserve estimation."

Jan 1, 1991

"The ventilation-related risks from mines with elemental sulphur include dust explosions, spontaneous combustion with emission of heat and toxic sulphur dioxide or hydrogen sulphide gases, reactions with nitrates, corrosion, acid water, and pyrophoric reactions with naked iron or other metals. Elemental sulphur will form explosive mixtures in air at lower dust concentrations and at lower ignition temperatures than coal or sulphide dusts. Potential controls include primary ventilation circuit design, control of dust deposition and static discharges, enclosing steel surfaces, inert stone dusting, FRAS ducting, humidifying the air, alternate stench gas, self-contained self-rescuers with goggles, careful siting of underground infrastructure, controls on explosives formulations and procedures, mining method selection, controls on surface temperatures and protection of equipment, careful materials selection for ventilation seals and changes to worker clothing and training.INTRODUCTIONSulphur (“Brimstone” in biblical times) is one of the world’s most important industrial feedstocks and is used in a wide range of chemical processes and industries. Until the early 20th Century, most of the world’s production of sulphur came from ‘conventional’ underground mines in Sicily (Demetra produzioni, 2006; Bellia, 2006). This was a hazardous activity. The Frasch solution mining process replaced traditional underground mining of sulphur until the late 20th Century. Most of the world’s production of elemental sulphur is now as a by-product from sour gas produced in petroleum refineries and natural gas installations (Anon, 1993). As such, there is considerable experience in understanding and managing the hazards of elemental sulphur in chemical plants and surface transport.Whilst rare, underground mines with high elemental sulphur contents (as a gangue mineral) create an unusual range of mine design and operational issues, including many ventilation-related ones. The key hazards from elemental sulphur include: primary and secondary elemental sulphur dust explosions, fires and burning (with emission of heat and sulphur dioxide or hydrogen sulphide gas), reactions with nitrates used in explosives, corrosion of steel and other metals, generation of acid water (especially at higher water temperatures), and pyrophoric reactions with naked iron (e.g., ground support, ladderways or underground fixed plant) or other metals including silver and copper (e.g., used in electrical components and equipment)."

Jan 1, 2019

By Pamela Paradis-Sokoloski, Deni Thibodeau, J. Denis, Samantha J. Espley, P. O’Donnell

"During the previous decade, the role of spray-on liners within the mining industry was limited to providing a corrosion resistant coating to screen and bolts; however, increasingly, liners are being used as ground support products. Expanding use and testing of liners have demonstrated their ground support function, yet the definitive support mechanism is still under debate. The most promising theory is the retain/hold/reinforcement concept (Kaiser et al.,1992). This conceptual theory has been the basis for the recent underground trials at INCO where, specifically, shotcrete and MIROC Mineguard were tested in two trials to further define limitations and applications of each liner.In a cursory overview, shotcrete is becoming accepted as a support product, while Mineguard is only slowly gaining acceptance.This discrepancy is the result of the corresponding life-spans within the industry, whereby shotcrete has had wide-spread use for decades, yet Mineguard has only recently been introduced. Currently at INCO, shotcrete is primarily used: to provide support in poor ground conditions, to add stability when developing through backfill, and to provide damage control in seismically active mines. It is also used to protect production headings and secondary-blasting chambers from fly-rock damage during blasting. Despite an obvious support function of the liner, shotcrete has always been used in addition to bolts and screen. Comparatively, Mineguard is still in the testing stage, where the greatest potential is increased productivity for applications in multi-tasking development headings. In this scenario, Mineguard provides instant support to replace screen, and bolts temporarily. When the heading has advanced, the drill and support crews work in tandem, drilling off the next round and installing bolts for long-term radial support, respectively. Other potential applications of Mineguard are within production headings to replace screen in the back, and screen and bolts in walls. The potential for both liners to replace conventional support is clearly war-ranted, such that defining the support role was the primary goal of the two underground trials."

Jan 1, 1996

Several inorganic reagents and organic polymers were tested as depressants in the single mineral flotation of ultrafine iron oxide and hydroxylapatite with Dowfroth 250 as a frother. It was observed that the inorganic reagents and the low molecular weight polymers generally caused dispersion of the ultrafine particles, and consequently their recovery into froth products more or less equaled the recovery of water. On the other hand, the high molecular weight polymers caused different degrees of flocculation of the ultrafine particles, and their recoveries were much lower than the recovery of water. These observations pointed to a need to re-define flotation depressants in fine particle flotation. The traditional definition of a flotation depressant, i.e., to make particle surfaces hydrophilic by forming a hydrophilic film and/or by removing collector and activator coatings, is sufficient for relatively coarse particles. However, to prevent fine and ultrafine particles from floating, a successful depressant should not only make the particles hydrophilic, but also enlarge the particle sizes so that they do not enter the froth product by mechanical entrainment. Polymeric depressants are ideal for these purposes. The different schemes to use polymeric depressants in the selective flotation of fine and ultrafine particles were discussed These schemes involve the integration of the polymeric depressants into other size enlargement processes such as shear flocculation, oil agglomeration, etc., for hydrophobic particles.

Jan 1, 2004

By Keith Haddock

"The Sheerness Mine, a new surface coal mine located near Hanna, Alberta, went into full production in mid-1995. The mine, which is operated by Luscar’s subsidiary Forestburg Collieries (1984) Ltd., has the design capacity to supply up to 2.1 million tonnes of sub-bituminous coal per year to the adjacent Sheerness Generating station under a 30-year contract. This paper documents the construction phase of this project and highlights the major equipment purchases as well as the construction of the mine facilities. The paper also focuses on some of the areas where cost savings have been achieved that have allowed the mine to come on stream six months ahead of schedule, and under budget. Project ReviewMine DescriptionThe Sheerness Mine is located 25 km southeast of the town of Hanna in southeastern Alberta (Fig. 1). The mining property occupies the western portion of the Sheerness CoalField and borders the Montgomery Mine, operated by Manalta Coal Ltd. in the east, and Highway 36 in the west. The Montgomery Mine and the Sheerness Mine exclusively supply the total coal requirement of the adjacent Sheerness Generating Station. The station is owned jointly by Alberta Power Limited (APL) and TransAlta Utilities Corporation (TAU). APL is the operator. Manalta’s Montgomery Mine has supplied coal to the Sheerness Station since its opening in 1986. Coal is shipped by truck from the mines over a network of haul roads to the coal receiving hoppers located on the east side of Highway 36."

Jan 1, 1997

By M. B. Kime

"Discrete-element method (DEM) modelling is a powerful tool for studying particulate systems within the mineral processing industry. DEM simulations were conducted to investigate the power draw, load behaviour, and impact energy profile of an experimental ball mill under different milling conditions. The variables considered were mill rotational speed (percent critical speed), ball size, and lifter face angle. The simulation results indicated that the grinding efficiency would be enhanced by using 80% critical speed, 30 mm ball diameter, and 45° lifter face angle. These findings can be useful in guiding actual ball milling tests involving an ore sample.RÉSUMÉ La modélisation par méthode des éléments distincts (MED) est un outil puissant qui permet d’étudier les systèmes particulaires au sein de l’industrie de traitement des minerais. Des simulations par MED ont été menées de façon à étudier le profil de la consommation énergétique, du comportement de la charge et de l’énergie de rupture d’un broyeur à boulets expérimental dans diverses conditions de broyage. Parmi les variables prises en compte figuraient la vitesse de rotation du broyeur (vitesse critique en pourcentage), la taille des boulets et l’angle de coupe de la cornière élévatrice. D’après les résultats de la simulation, on pourrait améliorer l’efficacité de broyage en utilisant une vitesse critique de 80 %, un diamètre de boulet de 30 mm et un angle de coupe de 45 ° de la cornière élévatrice. Ces résultats peuvent se révéler utiles pour les essais concrets de broyage à boulets impliquant un échantillon de minerai.INTRODUCTIONComminution is a very energy intensive process. It consumes approximately 5% of the electricity produced worldwide and more than 50% of the total energy used in mineral processing plants (Pokrajcic, 2010). Among all the comminution stages, ball milling is one of the most energy intensive processes. In ball mills, rotational movement provides the rise of the load and the media that are projected and impact on the mill shell at lower angular displacement, resulting in particle breakage. Ball mills are able to reduce particle size over a relatively wide range of particle sizes. This explains their wide applicability in research laboratories and the mineral processing industry."

Jan 1, 2017

By K. J. G Hedges

"Once a health based guidance limits for exposure to diesel exhaust have been established, and as part of a multi-disciplinary team, the program for exposure reduction should incorporate the plan-do-check-adjust cycle. Setting a suitably protective (health based) occupational exposure limit (OEL) for diesel particulate matter (DPM) and nitrogen dioxide is a key driver to reduce exposure. It is important to go beyond regulations and reduce exposure to diesel exhaust, DPM, as low as reasonably achievable (ALARA) such as that prescribed under the Australia, Queensland Mining and Quarrying Safety and Health Regulation 2017 where under section 135 Limiting workers exposure, the workers exposure must not exceed the exposure limit applying to the worker for the hazard; and is ALARA. It appears that previously acceptable OELs are no longer safe. Therefore it is important that the internal responsibility system be implemented and the precautionary principle approach be followed, especially as it may be some time before a suitably protective OEL specifically for DPM is in place. One leading multi-national mining company BHP Billiton has acknowledged a significant lag that exists between regulatory action and the level of science that informs health risk. This company is managing exposure to diesel exhaust to as low as technically feasible. This same company that has set an interim target for managing diesel exhaust to 0.03 mg/m3 is achieving these levels which paves the way for other mining companies and general industry including construction. The Occupational Cancer Research Centre 2017 recommends reducing personal exposure to within 0.02 mg/m3 (EC) for underground mining and 0.005 mg/m3 for other workplaces. Controlling DPM is important to prevent cancer however it is also important that that nitrogen dioxide (NO2) be reduced (ALARA) and that careful selection of control technology be considered such as the proper selection of a diesel oxidation catalyst so that the level of NO2 does not in fact increase. The example from BHP Billiton provides a leading practice including using a multi-disciplinary approach and the importance of controlling emission at source and having an auditable diesel emissions based monitoring program in place."

Jan 1, 2019

By E. Best

In 2003, Phelps Dodge Mining Company decided to pursue the design and construction of a Central Analytical Laboratory to provide chemical analyses for their Arizona and New Mexico operations. This centralized approach was selected in place of refurbishing six (6) older laboratories that operated at the various Phelps Dodge sites, and which would not have permitted full automation and use of robotics. The new lab was designed by the Process Technology Center (PTC) Material Characterization Group in cooperation with IMP Group. The Central Analytical Service Center (CASC) encompasses fully automated sample preparation of blast holes and geological samples weighing up to 15 kg/sample. The CASC also includes the first "wet chemistry module" worldwide to be operated by robotics systems to perform Total Cu, Acid Soluble Cu, and Quick Leach Tests (QLT), and a fully automated lab for electrowon copper cathode. The new lab also offers flexibility for handling specialty samples and analyses by either semi-automated or manual mode. Data handling and transfer is accomplished using the commercially available StarLIMS system. Commissioning was accomplished within five (5) months of startup during which the CASC also handled 86% of a full production load. The 24/7 lab operation has already exceeded its design capacity, has achieved considerable savings in operating cost, reduced sample preparation errors, and significantly increased analytical quality.

Jan 1, 2007

By S. Mathieu, R. Mennillod-Blondin, P. Cousin, N. Valle, H. Bouzahzah, P. Marion

The gold deposit of the Lapa mine has a complex mineralogical gold state with coarse and fine native gold, aurostibite and submicroscopic gold within arsenopyrite. A specific mineralogical characterization of the refractory fraction was conducted combining various techniques such as optical microscopy, electron microscopy, electron microprobe and secondary ion mass spectrometry. In parallel, the mineral processing behaviour and the recovery of the refractory gold were studied by pressure oxidation and cyanide leaching. This paper presents the mineralogical methodology developed to characterize the refractory gold distribution within arsenopyrite. These results are presented and interpreted in order to plot gold recovery versus sulphide oxidation. The comparison of the metallurgical behaviour yields predicted from the mineralogical data and the one calculated from leaching tests shows a good agreement and allows mineralogical explanations of the gold metallurgical behaviour.

Jan 1, 2011

Cansolv® S02 Scrubbing Technology was described in a paper in Copper/Cobre 03. Four years on, the technology is operating at a full scale production facility.Hindustan Zinc Limited expanded their capacity by installing the AUSMELT process. The process proceeds through smelting, slag reduction, slag cleaning and holding stages sequentially in the same vessel, resulting in widely varying off gas characteristics. The off gas is suitable for treatment is a conventional acid plant for a modest proportion of the day, but at other times produces off gas too high in S02 to be discharged to atmosphere. Cansolv® S02 Scrubbing Technology was identified as a means of effectively removing the S02 down to low levels from the off gas during all stages of the pyrometallurgical process. Furthermore, the Cansolv® S02 Scrubbing System Technology produces high purity S02 that allowed for the captured S02 to be directed to an existing acid plant, avoiding the capital cost of new acid making capacity.

Jan 1, 2007

By R. V. Fox, L. K. Sinclair, D. L. Baek

"In this study, rare earth elements were recovered from bastnasite concentrate and waste fluorescent lamp phosphors using supercritical carbon dioxide extraction with a nitric acid/tributyl phosphate adduct. Several pretreatment methods were used to alter the crystal structure of the source materials, and thus improve rare earth element recovery. Pretreatment methods included 1) dry roasting of the source material at 730oC, 2) decomposition with 50% sodium hydroxide solution at 150oC for 4 hours, and 3) decomposition with 12 M sulfuric acid at 300oC for 4 hours. Treated and untreated samples underwent supercritical extraction at 24 MPa and 65oC for 1 hour. Untreated bastnasite and phosphor samples showed <10% rare earth element recovery, but sodium hydroxide digestion resulted in >60% recovery for most rare earth elements. Dry roasting of the bastnasite concentrate was also effective, resulting in >60% recovery for cerium.INTRODUCTIONRare earth elements (REEs) consist of the 15 lanthanides, scandium, and yttrium. Scandium and yttrium are included because they are in the same group as lanthanum, appear in many of the same ore deposits as the rest of the lanthanides, and exhibit many similar chemical properties. REEs are used in a wide array of applications including electronics, magnets, catalysts, glass, and solid-state lighting (Xie, Zhang, Dreisinger, & Doyle, 2014). Because of China’s continued dominance of worldwide REE production, the United States Department of Energy has sought to diversify domestic supplies of REEs (United States Department of Energy, 2011). A key part of this strategy is the development of improved extraction methods for both ores and recycled sources.Supercritical fluid extraction (SFE) is a promising technology for extraction and separation of rare earth elements. Contact with an acid adduct dissolved in supercritical carbon dioxide allows for the rapid extraction of REEs from solid matrices. Supercritical CO2 has several potentially useful properties as a solvent, including high diffusivity and the ability to tune solvation properties by adjusting pressure. Such tunability may have applications in separating the REEs once they have been extracted from the solid phase. Tributyl phosphate/nitric acid adducts (TBP:HNO3) are a particularly promising class of adducts for SFE extraction of rare earth elements. Using TBP:HNO3 adducts in supercritical CO2, several researchers have successfully extracted REEs from their oxides (Wuhua, Pijia, & Yongjun, 2010; Zhu, Duan, Xu, & Zhu, 2009). However, there is a complication in applying this technique to many types of ores and recycled sources: REEs are often locked in refractory minerals which are resistant to acid attack, resulting in limited recovery in supercritical extraction."

Jan 1, 2016

By G. S. Farnham

Abstract This paper lists the interests of the Physical Metallurgy and Chemical Research laboratories of the Metallgesellschaft, which were visited by the authors, members of a group of Canadian investigators sent to Germany by the Department of Reconstruction in 1945. The Physical Metallurgy Research Laboratory The following information was obtained from Professor E. Schmid, Chief of the laboratories. It is understood that Dr. Schmid is a former Nazi and was to be removed from his post in November (1945). Aluminium Research The laboratories investigated the corrosion resistance of the high-strength aluminium-magnesium-zinc alloys. The same test procedure as used by V.L.W. was followed and Dr. Schmid co-operated closely with Dr. Brenner on this project. Intercrystalline corrosion was combatted by additions of chromium, titanium, or vanadium, and the work in this field parallels that of Dr. Brenner of V.L.W. * Dr. Schmid reports that Bollenrath and Siebert believe that corrosion difficulties with these alloys can be overcome to some extent by heat treatment. He himself was of opinion that the correct answer lay not only in correct alloying but also in correct heat treatment. The heat treatment involved either interrupted quenching or a change in quenching rate from a solution temperature of 500°C. The procedure is either a slower cooling from solution temperature or an interrupted cooling with a holding period at l50°C. Work had been done on piston alloys, the 11-13% Si, 1% Ni, 1% Cu, and 1% Mg being the favoured material. This is called Lo-Ex and is similar to Mahle 124 or KS1275.

Jan 1, 1946

By H. A. Khorami, T. Wong, B. Velapatino, E. Asselin, T. Donnelly, E. Bryce, R. Dixon

A copper–nickel concentration gradient alloy was designed and fabricated through a powder metallurgy (PM) process. Copper and nickel powders were mixed with different weight ratios from 0 to 100% copper in 10% increments. Each powder mixture was poured inside a cylindrical die and compacted between two punches using a hydraulic press machine at pressures up to 70 MPa, resulting in approximately 1 mm thick layers (discs) of pressed Cu–Ni powder. These 11 Cu–Ni compacted powder layers, i.e. 0–100% Cu with 10% increments, were then compressed together with pressures up to 420 MPa to form a green part. The green part was sintered in a vacuum furnace at 1000°C for 10 hours to form a solid mass (PM part) of Cu–Ni concentration gradient alloy. In the sintering process, Cu and Ni particles fused together and formed a single piece due to diffusion of the atoms across the boundaries of the particles. The diffusion of atoms also converted the stepwise concentration change into a uniform concentration gradient. INTRODUCTION Copper has numerous applications in different industrial sectors due to its superior physical, electrical, mechanical and chemical properties such as its excellent thermal and electrical conductivity, resistance to fatigue, high ductility, and resistance to corrosion. Moreover, copper and its alloys have natural antimicrobial properties. This has opened up new applications for copper–based self–disinfecting surfaces in healthcare in an effort to mitigate healthcare–associated infections (HAIs). HAIs affect millions of patients each year, leading to significant morbidity and mortality as well as financial losses to healthcare systems (World Health Organization, 2016). HAIs spread through three main routes: (a) iatrogenic in which HAIs are a direct consequence of medical encounters and/or treatment; (b) person to person where organisms are transferred between healthcare workers, patients, and visitors; and (c) environmental where transmission occurs via contaminated surfaces and equipment (e.g. doorknobs, railings, toilets/commodes, medical carts). The use of antimicrobial copper–based materials on high touch surfaces could diminish pathogen transmission via this latter rout. This has subsequently led to the development of a variety of copper–based materials for use in healthcare settings and promoted the investigation of the antimicrobial efficacy of copper–based materials.

Jan 1, 2019

By Simon C. Dominy, Alwyn E. Annels, Paul Wheeler, Suzanne P. Barr, G. Simon Camm

Narrow veins are an important world-wide source of silver, tin, uranium and particularly gold. To potential ?nanciers, this style of mineralization is viewed as high risk because of the often relatively small resource involved and high cost of estimation. In many cases diamond core drilling will not enable resource estimation beyond the inferred and indicated categories. Exploratory under-ground development is required to de?ne measured resources. The de?nition of geological and grade continuity are major factors in narrow vein assessment. A measured resource must be based on strong geological and grade continuities. Narrow veins, generally less than 3 m wide, are complex geological phenomena, which commonly display unpredictable geometry and grade distribution. Variations in structural continuity, dip, strike, width, mineralogy and speci?c gravity are common. Veins may be composite, with ore-grade mineralization restricted to a speci?c structural domain. Branches, intersections and braided zones are common features. Potentially high-grade zones are often localized within ore shoots, which are surrounded by barren/low-grade regions. Resources must be determined as closely as possible to reality and re?ect the distribution of the commodity in the rock. Estimation has three main requirements: (1) geological study to determine orebody nature;(2) estimation of tonnage and grade, and (3) the presentation of this information using a classi?cation that is clear, unambiguous and bankable. Estimation methods employed are either classical or geostatistical; however, classical methods are often used because of the dif?culties in applying geo-statistics. Grades generally show a strong positively skewed distribution testifying the presence of high-grade values. Problems exist in the applicability of cutting outlier values risking over- or under-estimation of grade. It is generally believed that where resource estimates are in error, poor geological control is usually the cause. Overestimation can lead to the closure of a mine through lost revenue and capital. An understated estimate can result in an opportunity missed for pro?t and/or greater economies of scale. De?nition of reserves involves the consideration of economic and engineering data, to decide which part of the resource is economically mineable. Geology plays a similarly important role at this stage in the assessment of likely mining method, dilution, recovery etc. Throughout resource/reserve estimation, it is crucial that the amount and quality of the data and the geologist’s experience are relevant. The impact of geological understanding on estimation is often undervalued or assumed to be of lesser importance than ?nding grades and tonnages. This paper discusses the geology of narrow vein deposits and the importance of geology in their evaluation.

Jan 1, 1997

By Simon C. Dominy, Alwyn E. Annels, Paul Wheeler, Suzanne P. Barr, G. Simon Camm

Abstract-Narrow veins are an important world-wide source of silver, tin, uranium and particularly gold. To potential financiers, this style of mineralization is viewed as high risk because of the often relatively small resource involved and high cost of estimation. In many cases diamond core drilling will not enable resource estimation beyond the inferred and indicated categories. Exploratory underground development is required to define measured resources. The definition of geological and grade continuity are major factors in narrow vein assessment. A measured resource must be based on strong geological and grade continuities. Narrow veins, generally less than 3 m wide, are complex geological phenomena, which commonly display unpredictable geometry and grade distribution. Variations in structural continuity, dip, strike, width, mineralogy and specific gravity are common. Veins may be composite, with ore-grade mineralization restricted to a specific structural domain. Branches, intersections and braided zones are common features. Potentially high-grade zones are often localized within ore shoots, which are surrounded by barren/low-grade regions. Resources must be determined as closely as possible to reality and reflect the distribution of the commodity in the rock. Estimation has three main requirements: (1) geological study to determine orebody nature; (2) estimation of tonnage and grade, and (3) the presentation of this information using a classification that is clear, unambiguous and bankable. Estimation methods employed are either classical or geostatistical; however, classical methods are often used because of the difficulties in applying geostatistics. Grades generally show a strong positively skewed distribution testifying the presence of high-grade values. Problems exist in the applicability of cutting outlier values risking over- or underestimation of grade. It is generally believed that where resource estimates are in error, poor geological control is usually the cause. Overestimation can lead to the closure of a mine through lost revenue and capital. An understated estimate can result in an opportunity missed for profit and/or greater economies of scale. Definition of reserves involves the consideration of economic and engineering data, to decide which part of the resource is economically mineable. Geology plays a similarly important role at this stage in the assessment of likely mining method, dilution, recovery etc. Throughout resource/reserve estimation, it is crucial that the amount and quality of the data and the geologist’s experience are relevant. The impact of geological understanding on estimation is often undervalued or assumed to be of lesser importance than finding grades and tonnages. This paper discusses the geology of narrow vein deposits and the importance of geology in their evaluation.

Jan 1, 1997

By L. Xia, B. Hart, G. Gingras, M. Furlotte

Plant and laboratory test work was performed in order to optimize a copper/zinc flotation separation circuit at Matagami concentrator, Canada. The testing identified a significant difference between the laboratory testing and the plant flotation, particularly for the sphalerite recovery in the rougher copper concentrate. Tests indicate that sphalerite recovery of the flotation concentrate in the laboratory testing was significantly higher than in the plant. The ToF-SIMS surface analysis identifies surface species responsible for the discrepancy in Zn recovery. It shows that sphalerite flotation is in response to the collector attachment and a significant enrichment of Cu on the surface of sphalerite grains. A comparative surface chemical analysis was performed on both sphalerite and chalcopyrite grains from the plant flotation and laboratory testing in order to identify surface species variability between the two testing. Two significant observations were revealed. First, there is considerably more hydrophilic iron oxyhydroxide on sphalerite surface from the plant flotation sample relative to those from the lab testing. The secondary coating likely completely or partially passivates sphalerite surfaces, reducing Cu enrichment and hence sphalerite floatability. Secondly, comparing the surface chemistry on sphalerite and chalcopyrite, the hydrophilic iron oxyhydroxide species have preference for the sphalerite grains relative to chalcopyrite. Despite numerous studies on the effect of galvanic coupling during grinding, there is limited documented evidence on the effect of the milling environment on the flotation and plant operations. This observation suggests that interaction between sulphide minerals and grinding media have a significant influence on subsequent flotation. This paper discusses the results of a detailed surface chemical evaluation of sphalerite grains from both the plant and laboratory testing in the context of grinding environments and pulp chemistry.

Jan 1, 2016

By Lifeng Yang, Xiang Zhang, Liang Yuan, Yonghui Wang, Bing Hou, Mian Chen, Rixing Zhang

Large-scale hydraulic fracturing technique has been widely applied to the development of shale gas reservoirs, where the interaction between natural fractures and critical fracture zones has substantial impact on the propagation of hydraulic fractures. Therefore, it is of significant importance to understand and experimentally verify such mechanism. To reach this end, tri-axial fracturing tests were implemented on 400mm×400mm×400mm block samples collected from Longmaxi shale outcrops. The interplay between hydraulic and natural fractures was investigated during the tests, factoring in the role of pump rate in affecting the created fracture network. Based on the experimental results, the critical fracture zone, defined as the weak formation zone nearby the wellbore created by staged pressure implementation that is observed rapid fracture propagation upon next stage of pressure increase, was thoroughly investigated. The analysis illustrates that given the high brittleness of the shale formation, abundant critical fracture zones are generated around natural fractures with pressure building up at a relatively low pump rate. As the pump rate increases, hydraulic fractures initiate and come into play with critical fracture zones, implying emergence of a large number of micro-cracks. A changing pump rate modifies the way of interaction between hydraulic and natural fractures and the subsequent formation of fracture network. Long term fracturing fluid injection with relatively low pump rate below the activation of critical zones is suggested. Also proposed is appropriate timing when applying a specific pump rate that will contribute to the improvement of hydraulic fracture propagation.

Jan 1, 2015

By A. M. Martinez, L. Melis, R. C. Peláez, L. G. Garcia

Orovalle Minerals S. L. operates a copper/gold mine in the Asturias region of northern Spain, with the operation dating back to December 1997. The feed to the El Valle mill, consisting of oxide/sulphide (skarn) mineralization, is highly variable, even on a shift by shift basis and presents challenges to the mill operating staff on a daily basis. The mineralogical characteristics of the ore are quite complex with copper present as native copper and sulphides as well as copper minerals with deleterious elements. Gold is present as native gold and electrum. The mill circuit includes SAG/ball mill grinding, gravity recovery of native copper and gold, flotation of copper concentrate, carbon-in-leach gold recovery and SO2/air cyanide destruction. The paper will provide a description of the different unit operations and present operating data of the mill operation.

Jan 1, 2019

By T. Donkin, B. Patterson, M. I. Guthrie, J. T. Ross

"The interest in the use of sensor-based particle ore sorting has increased significantly with the recent advances in the sorting technologies and higher capacities per unit. This technology has the potential to provide great value in processing lower grade ores from the mine whilst delivering higher grades to the mill as well as in upgrading waste rock into ore. Typically, the focus is on the amenability of the ore to ore-sorting and associated reductions in the consumption of energy, water and consumables. However, layout has a significant impact on the installed cost of a concentrator and the layout impacts from fitting an ore-sorting circuit into the concentrator plan need to be carefully considered. This paper examines layout considerations that play an important role in ore sorting projects. These include additional crushing and screening requirement, transportation of the rejected material back to the waste stockpile (mine fleet requirements) and effects on concentrator footprints.INRODUCTION Ore sorting has been practiced throughout history with an early report by Agricola in 1556. Metallic and non-metallic minerals were extracted from rocks by laboriously breaking them with hammers and picks and hand-picking selected material with higher grade off a table. The concept has not changed but the sorting technology has evolved significantly over the last 20 years. Ore sorting is usually a dry process in which a portion of the material is rejected based on mineral properties and/or grade. The methods used for sensing ore particles cover a large range of physical properties. A variety of sensors are available that differ on the discrimination technique that is used, which include: photometry, radiometry, conductivity, magnetism, microwave, X-ray transparency: X-ray transparency and luminescence and UV fluorescence (Sivamohan and Forssberg, 1991; Wotruba, 2006). There are two main ore sorting techniques: particle ore sorting and bulk ore sorting. According to Nadolski et al (2018), the potential for sorting is determined though analysis of grade heterogeneity within the orebody (greater heterogeneity represents more opportunity to add value to a project) at the scale of the intended sorting unit size."

Jan 1, 2019

By Edward R. Lauer

Energy conservation is an integral part of Canada&apos;s energy strategy. We must pursue conservation and energy management vigorously if we are to remain competitive in domestic and world markets, and minimize our reliance on external energy sources. Energy management in industry is discussed from three viewpoints: (l) as a means of directly improving profitability; (2) as a major factor in the supply picture; and (3) as a significant influence on Canada&apos;s balance of payments and over-all economic well-being. The Federal role in promoting a voluntary industrial energy conservation program is described.

Jan 1, 1977