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By D. E. Salman, R. R. Maclachlan, R. J. Barclay

"There is a considerable resource of data for spherical charge cratering, both as single charges and in row-of-charge geometr(1). The data are. however, based on cratering performance to a single free planar surface.In practice. the more common circumstance involves an angular surf ace geometry. such as occurs at the toe of a bench or the wall of a stope. It is for the purpose of investigating this circumstance that the described test work was conducted.The test objectives were: (1) to observe the change in single-charge cratering performance between planesurface and angle geometry; (2) to identify the optimum performance of single charges cratering to a plane surface. cratering from a bench sub-grade position and cratering from a condition of zero sub-grade or stope wall geometry; and (3) to observe the performance of row-of-charges cratering to an angular surface at various row burials and spacing. The row charge burial and spacing dimensions were to be expressed in simple numerical multiples of single-charge depth-of-burial data."

Jan 1, 1981

By J. Bhattacharya, S. K. Mukhopadhyay, S. K. Pal

"While time and again many authors have categorically stressed the restoration of the environment, very little effort has been made in the mineral industry to develop the economy of environmental control. There are many abatement procedures that search a maze of variants. Among them pricing environmental damage seems to be more logical and easily implementable.IntroductionMining as an operation has a severe impact on the Earth's natural resources. While economical environment control is much sought after, solutions are often varied and complex, and can differ in the problems of single or multiple mine sites.Determination of Optimum use LevelsIn “mining environmental control"" it is required to strike a balance to find optimum use levels. The solution is to find where the welfare benefits equal the cost involved to curb the degree of environmental damage (Fig . I) . In the mining industries this can be done by modifying the production/extraction process itself. For most pollutants, the marginal costs of control will exceed the benefits from further reduction of damage long before the zero pollution damage point is reached (Fig. I). From an economic perspective the optimal alteration of environment by mining would occur at z; pollution continues to be caused by ""zy"" control units, but it would be inefficient to pursue the redemption efforts further because the marginal cost involved would exceed marginal welfare benefits."

Jan 1, 1992

By L. Cáceres, G. Leinenweber, P. Bustamante

"Given the severe scarcity of fresh water sources in Northern Chile the use of seawater has become the only alternative to allow mining expansion. This option however poses several technological challenges as a result of the high concentration of natural salts that promote various forms of metal corrosion. Therefore the steel piping protection has been a constant challenge for design engineers responsible for solving the problems of corrosion. Known protection alternatives are varied and expensive, a few of them are rubber coatings, protection based centrifuged concrete, extra wall thickness of pipes in combination with corrosion inhibitors, extra wall thickness of pipes without using corrosion inhibitors, and the use of highly corrosion resistant steel materials.In this framework the aim was to study the corrosion kinetics of carbon steel pipe API 5L X70 under electrochemical and weight loss testing. The test conditions include a range of seawater velocities between 0.2 to 3.0 m/s.For electrochemical experiments the API 5L X70 steel specimen was a 4 mm diameter disk embedded in an 8 mm diameter Teflon rod and exposed to seawater. Duplicated coupons were placed in a standard test apparatus that was built according to the standard ASTM D 2688 – 94.The main results were: a) corrosion mechanism explained in terms of the counterparts partial processes which are the hydrogen evolution and oxygen reduction reaction; b) for the test specimen a corrosion band like feature that suggest a lateral dispersion of aggressive solutions from corrosion pits; c) a range of corrosion rates between 1 and 1.96 mm/year for flow rates between 0.2 and 3.0 m/s; and d) a convenient inhibitor dose between 20–25 mg/L for optimum inhibition efficiency to obtain a maximum value of 80% for corrosion efficiency."

Jan 1, 2016

By G. Banini

Prior to installation of High Pressure Grinding Rolls (HPGR) at PT Freeport Indonesia (PT-FI) a series of laboratory tests were carried out to determine the design parameters and also determine key performance indicators (KPIs) for the industrial unit. The design parameters derived from the lab test work were then scaled up to estimate the industrial capacity of the HPGRs to be installed. These parameters include specific power draw, specific throughput, and specific force, rolls speed, product size distribution and wear rate of the rolls. This paper compares the performance of the scale-up procedure against the installed industrial size HPGR. Overall, the specific throughput of the industrial size HPGR is higher by a minimum of 30% compared to the expected scale-up value. As a result of the high specific throughput, the specific power draw and grind sizes are below the scale-up expectations in the commercial application. The impact of these factors also contribute to a lower than expected wear rate on the industrial rolls. Installed rolls achieved a service life in excess of 18,500 hours relative to the target of 6,850 hours predicted from the laboratory testing.

Jan 1, 2012

By Turgut Yalcin

"In this study, potential benefits of focculant usage were explored in the processing of mill tailings by hydrocyclones. Tests conducted on copper-nickel mill tailings have demonstrated that, under suitable conditions, flocculation could significantly enhance solid-liquid separation in hydrocyclones. For example, at a feed pulp density of approximately 9%, focculant-assisted hydrocyclone produced an underflow with over 98% solids recovery, compared to a recovery of less than 53% with conventional hydrocyclone. However, feed pulp density was found to be a critical factor, and tailings with pulp densities of greater than about 15%required a two-stage hydrocyclone operation where the focculant-assisted hydrocyclone was employed at the second stage to process the overfow of a conventional hydrocyclone.The underflow and overflow products obtained from the focculant-assisted hydrocy-clone may be discharged into tailings dams in the same manner as those produced by gravity thickeners. The focculant-assisted hydrocy-clone would, however, provide a higher throughput."

Jan 1, 1996

Weekly Capacity ? Current Schedule Rate (198.5 tonnes / hour) X Skip Time (112.7 hours) X Effectiveness (85%) = Weekly Capacity (19,015 tonnes) Capacity Conclusions - Existing hoists optimized are best option for Fraser Morgan (>20M + schedule for other). - Peak will have to be managed. - Critical to have equipment & infrastructure in best possible condition to ensure reliability.

Feb 1, 2008

By C. A. Pickles

Microwaves are being applied industrially in a number of fields and possess a number of potential advantages that could be applied in extractive metallurgy. Microwave heating has a number of unique characteristics, which distinguish it from the conventional heating methods. In microwave heating, the absorption of energy occurs at the molecular or atomic level and therefore the heat is generated within the material itself. In conventional heating, the exterior temperature is usually higher than the interior, but with microwave heating, the temperature gradient is inverted and thus the interior temperature can be much higher than that of the surface. The energy densities in microwave systems can be relatively high and this in combination with the low thermal conductivities of oxide ores, can lead to very high internal heating rates. In this research, the application of microwave energy for the reduction of a nickeliferous silicate laterite ore has been investigated. The real and imaginary permittivities are the two fundamental properties which determine the microwave absorption characteristics of a material and these were measured for the ore, both with and without carbon additions using the cavity perturbation technique. The microwave heating and reduction experiments were performed in a 0 to 2 kW CTC microwave system. The effects of power input, processing time, sample mass and charcoal additions on the microwave absorption were investigated. Then reduction experiments were performed and the nickel grade of the magnetic concentrate and the nickel recovery in the concentrate were determined.

Jan 1, 2005

By Mark B. Thorpe

Golden Star Resources started gold mining operations in Africa in 1999 after 15 years of exploration in South America. At the time, the approach to local assistance was through "alternative livelihood" programs and the donation of infrastructure to local communities. This was initially successful with local community support. However, with time and on reviewing the implemented projects, it became evident that the success was limited and many if the projects were either poorly used or in disrepair. Through a review of the options, we decided to develop a community assistance model driven by the communities themselves, while keeping control of the finances and the actual construction of the projects. Through the formation of the Golden Star Development Foundation, we began to support community driven projects for local economic development. The evolution of economic development projects continued over the next several years with the addition of project requirements for partnerships with government, and finally an evolution to a partnered turn-key piece of infrastructure that we hand over to an agency for operation and ongoing maintenance. We are currently working with outside partners to further our economic development activities in Ghana to the benefit of our stakeholders.

May 1, 2011

By G. Girard, A. Larouche, J. Colbert, G. Doyer

"The Direct Chill (DC) casting process uses water to extract heat from molten aluminium and helps to control the solidification process. Many factors such as the water flowrate, water distribution around the mould and water impingement angle have significant impacts on the solidification process. It has been noted that the chemistry variation of the cooling water is also an important factor that has a major impact on the presence of defects on the ingot. A significant change in the water quality can produce defects on the ingots such as cracks, bleedouts, or runouts. Understanding the impact of water quality variation on ingots is therefore essential to ensure good ingot production and reduce defects. This paper aims at describing a new approach to follow the variations of process water quality over time. It is an original and innovative method, which is still under progress. A water quality and stability index (WQSI) is under development to evaluate changes in the water composition based on water physico-chemical parameters. The index is calculated by comparing each of the actual parameters with historical values previously modeled by a statistical law. It is a dimensionless number having an adjustable weight factor for each parameter. The positive or negative contribution of each parameter, with respect to the water cooling capacity, is taken into account to calculate the WQSI. The current selection of parameters is based on knowledge from the literature as well as on empirical experience. When the developed tool will be mature, it could be used to track water variations upon time and anticipate problems, enabling proactive actions to ensure good ingot production.INTRODUCTIONFor many years, the impact of water chemistry on heat transfer, during DC casting, has been of great interest in the aluminum industry. Several papers have been published to demonstrate the correlation between water chemistry and heat transfer (Yu, 1985), (Gildemeister, 2014). Although numerous studies do present the effects of water parameters (i. e. hardness, conductivity, oil, and grease…) on cooling capacity under controlled experimental conditions, they do not reflect the strong interactions between the parameters and variations present in a casting center. Wells and Cockcroft also demonstrated that laboratory based studies are not fully representative of real heat transfer in an industrial casthouse, there are too many factors involved (Wells, Li, & Cockcroft, 2001). In this context, it becomes very difficult to obtain a quantifiable relationship between the capacity of water to cool the ingot and ultimately the performance of the cast."

Jan 1, 2016

By Atulya Verma, Samantha Espley, Nashel Kalaka

Numerical modelling simulations of proposed mining sequences are used to evaluate mining induced stress concentrations and their migration associated with the progress of mining. This analysis is a standard practice for most prospective mining projects at various levels of feasibility study. The studies are usually initiated at the beginning of the mining cycle, on a global scale, and are maintained and updated throughout the life of mine (LoM) to identify or address local issues and the required remedies as and when needed. Developments in numerical modeling techniques along with advancements in computing technology and data storage/management capacity have given rock engineers access to a huge volume of data that needs to be analyzed and assessed. The most common approach to numerically evaluate stress concentrations and migrations in underground mines is to select the points of interest in a given volume such as the back of an excavation or points within pillars around critical infrastructure, and plot the stresses or a derivative of stresses over time to represent life of mine concentrations and migrations of stresses. The problem with this approach is the sharp gradient of stresses close to excavation boundaries. Slight changes in the location of selected points can change the stress concentration and migration patterns substantially and all generalized statements about LoM risk can be challenged in one way or another. For global stresses, the most common current approach of data analysis is by viewing series of pictures representing stress contours. In this approach, it is easy to overlook some critical detail and/or be masked by personal preferences of contour/picture representation. To overcome the problem of representing and analyzing huge volume of stress simulation data, the authors, through their experience at different mining operations, developed a volume-based technique to reliably evaluate mining-induced stress concentrations and migrations. The volume-based approach is for risk-based assessments of adjacent regions in the rockmass, in and around planned stoping excavations. The volume of interest is the entire ore body that is planned to be mined, but it could be just a part of the ore body depending on the specific use case. The risk identifiers are the induced stresses as compared to the strength of the rockmass. Over the LoM, the risk identifiers are tracked versus the corresponding excavation ratio of the zone. This approach is very effective in identifying the stages of mining that are contributing the most to the mining induced stress risk and the results can be used for proactive planning and mitigations measures such as alternative mining sequences, or stope sizes, or extraction methods. The approach has also been very successful in application at mature mines, particularly in assessing the re-initiation of mining in zone that has been dormant for some time. The volume-based approach allows for an assessment of the current state of the rockmass and the identification of future risks when planning resumption of mining activities.

Jan 1, 2023

By H. Gharahbagheri, S. Shafiei Zadeh, H. Hassan Nejad, Reza Roostaazad

In this paper, dissolution of vanadium from mining residue, in which vanadium is associated intimately with magnetite ore, was investigated via both bacterial ( aerobic and anaerobic) and fungal activity. Although bacterial activity was tangible, it could not reduce and dissolve vanadium in both aerobic and anaerobic experiments. However, in fungal leaching, after 30 days about 36.9% and 29.7% of vanadium was dissolved for a pulp density of 10 and 30 g/l, respectively. At the end, the concentration of metabolites usually produced by fungal activity was optimized and oxalic acid was chosen as the main agent for the leaching process.

Jan 1, 2014

By M. Ataka

Magnesium alloys are not easy to plastically deform at room temperature and may suffer from edge cracking at high reductions, especially during sheet rolling. In this study, the authors attempted to improve the rollability by the low-temperature hot rolling method, in which the rolling temperature range is lower than that of hot rolling, and also by the edge-heating method, which locally heats sheet edges.

Jan 1, 2006

By Osamu Inoue, Takashi Yamashita, Takashi Ikemoto

The expansion project in Naoshima smelter and refinery to meet enhancing recycling business of E-scrap was successfully completed in 2016 to have a capacity of 110,000 tpa of E-scrap treatment. Increasing treatment of E-scrap has raised the Ni content of copper anode to 4000 ppm on average, which is double the level of 10 years ago, and to 6000 ppm or more occasionally. The tank house has refined such copper anode to copper cathode with starter sheets. Since most Ni in Copper anode dissolves in copper electrolyte, the Ni content of the electrolyte has increased to 27 g/L and more. Ni accumulated in the electrolyte has increased power consumption during the electrolytic refining of copper, although cathode quality has been controlled satisfactory so far. In order to ensure sustainable operation while growing E- scrap business, the NiSO4 process has been expanded recently so as to recover Ni in the electrolyte more and the pressurized-leaching technology will be introduced to the slime leaching process so as to enhance the capacity of slime treatment and to improve Ni recovery in the near future. INTRODUCTION In recent years, the treatment amount of E-scrap at Naoshima smelter and refinery has increased according to the growth of its recycling business as shown in Figure 1, while impurities from E-scrap have concentrated in copper anode as well. Especially, Ni content in anode has been increasing remarkably since 2012, causing to raise Ni content in the electrolyte as shown in Figure 2. The increment of Ni content in copper anode and electrolyte has adversely affected the electrorefining process, slime leaching process, and NiSO4 crystallization process at the tank house. Such severe conditions provided opportunities to redesign the tank house to establish a robust process to which more Ni is acceptable.

Jan 1, 2019

By A. P. E. Dirige

The stability design of cemented backfills is normally conducted using conventional approaches. Analytical or numerical models, backed by trial-and-error methods, are the primary means used to describe or predict the support performance of backfills during mining. The stability of paste backfill free-standing faces is a major concern due to potential consequences to production, ore dilution and safety. Available analytical or mathematical models are developed based on assumptions of the failure modes that may occur when vertical fill faces are exposed during adjacent mining. Numerical modeling serves to provide an understanding of backfill strength and deformation behaviour. Such approaches offer inherent limitations and generally result in conservative designs. In this paper, centrifuge physical modeling was conducted not only for performance evaluation studies, including stability analysis, but to develop an understanding of the strength and deformation behaviour of paste backfill exposed faces when the adjacent ore zone is removed. The failure mode and mechanics of failure observed in the centrifuge model of a given prototype situation are discussed in detail. Centrifuge model results were compared to numerical modeling and it was concluded that a sliding block failure mechanism that resembles a circular slip appears to be the predominant failure mode.

Aug 1, 2013

By J. P. Nowlan

"This paper is an attempt to outline the structural problems at the Cochenour Willans mine, in so far as their details have been tentatively worked out. It must be emphasized that there are considerable data that can be interpreted in more than one way, and that further work may modify or completely change some of the hypotheses presented herein. Certain features, however, are sufficiently constant to warrant reliance on them when searching for extensions of orebodies.As the individual ore shoots usually have relatively small dimensions, but are often very high grade, structural details are of more than usual significance in laying out a mining programme. An illustration of this is a small shoot recently located and mined as a result of studying a minor slip cutting off a part of high grade gold ore in No. 319 stope. The shoot, which is bounded on three sides by slips, and on the fourth by the original stoping, was roughly triangular in plan, 20 feet on the base, and 40 feet in length. The average width mined was 4.5 feet, but the gold obtained totalled over 1,800 oz.The property lies in Dome township, east of McKenzie island, and consists of an original group of thirteen claims acquired from the Cochenour Willans syndicate, plus one additional group of five claims obtained by purchase from the Kelson Red Lake Gold Mines, Limited, and one other claim that rounds out the southeast corner of the block.The claims of the original group were staked by W. M. Cochenour, Dan Willans, and Horace Young, during 1926 and 1927. The Cochenour Willans Syndicate was formed in 1928, and until incorporation of the present Company work was carried on at varying intervals by several different interests, including Ventures Limited, Hollinger Consolidated, who sank a shaft to open up the 150-foot level, and by the Syndicate itself. The first ore from the property was shipped to the Gold Eagle mill by the present Company in 1939, and amounted to 4,959 tons, from which 2,360 oz. gold was recovered. The first brick was poured in December, 1939, and production has been continuous since that date. To the end of June, 1946, gold having a value of $5,982,000 has been produced from 345,033 tons of ore treated."

Jan 1, 1954

By B. D. H. Knights, N. B. du Preez

The recovery of the economy of the Democratic Republic of Congo has allowed for the rapid increase in production of copper from this region, while the increased price of cobalt continues to support the recovery of that country’s economy. This has enabled the modernization of the process technology used, particularly the change from direct electrowinning of copper to solvent extraction-electrowinning. With this change has come a variety of technical challenges in optimizing the recovery of cobalt from these sources. In this paper, we discuss aspects of the flowsheets for the production of cobalt from the ores of the DRC and Zambia, highlighting the technological improvements that have been made. Following this description of the practice, we assess the challenges of further improving the recovery and purity of cobalt from these sources. INTRODUCTION The African Copperbelt (Figure 1) is by far the biggest producer and holds the greatest reserves of cobalt (Sheed, 2015). However, the ores of this great mining region are extracted primarily for their copper content, and cobalt is a by-product. The ratio of copper-to-cobalt is between 6 and 20 to 1, with the ores from the DRC richer in cobalt than those from Zambia. The overall supply of cobalt, shown in Figure 2, is increasing due to an increase in demand for its use as a battery material. Cobalt is used in superalloys, hard metals, pigments, catalysts magnets, tyre adhesives, lithium-ion rechargeable batteries, and wear-resistant coatings, amongst others. Although these generic categories persist, Figure 3 shows how the relative usage of cobalt is changing due to the uptake of electric vehicles in China and Europe. Cobalt is a key element in lithium-ion batteries, and because it is widely anticipated that electric vehicles will be legislatively encouraged, it is anticipated that the demand for cobalt will rise. This anticipated increase in demand resulted in an increase in the price for cobalt, to which suppliers responded over-eagerly, and the price has dropped dramatically in the first few months of 2019, as shown in Figure 4. However, there is a clear cycle of price peaks in cobalt’s history.

Jan 1, 2019

By Patrick S. Hudd

Traditionally in hard rock mining, large diameter raise boring was thought of as 3.04 metre or 3.66 metre diameter holes 300 metres deep. Mine and ventilation engineers were challenged to design systems either incorporating such holes, or slashing and modifying to suit. Now, 5.49 metre diameter holes up to 1,000 metres deep are being excavated. The ability to pilot and ream such holes not only creates new options for mine engineers in mine ventilation system design, but also creates new opportunities in mine access. By combining holes of this diameter with the ability to accurately drill long pilot holes within the diameter of the pilot hole through the entire length of the hole, borehole hoisting systems are now fully capable of being main production or service accesses for mines. This paper will review the present day capabilities of large diameter raise boring, potential applications for such excavations and some considerations for companies contemplating using large diameter raise boring in their operations

Oct 1, 2010

By A. D. Mufch, G. P. Mitchell

"THE HARDY MINE of Falconbridge Nickel Mines Limited is located in Lot 9, Concession 1, Levack Township, Sudbury District, Ontario, 20 miles northwest of the city of Sudbury, and a mile west of the town of Levack. The ore deposit is one of the many nickel-copper sulphide bodies found on, or near, the lower contact of the well-known Sudbury norite-micropegmatite irruptive, and is one of a family of ore deposits which occur on the northwest rim of the irruptive.The property was acquired by purchase in 1935. In the same year a magnetometer survey along the footwall contact of the norite, which is covered by about 150 feet of glacial sands and clays, first indicated the location of the orebody. Drilling from 1935 to 1942 outlined the extent of the ore. Shaft sinking was commenced in the fall of 1951, and the mine is now approaching full production at a rate of about 300,000 tons per year.There are several major differences between the geology of the Levack area and the Falcon bridge area, which lies at the opposite extremity of the irruptive, 28 miles to the east. The purpose of this paper is to describe the essential features of the geology of the Levack area as seen in the Hardy mine, and to supplement the recent papers on other properties in the Sudbury area by Davidson (1), Lochhead (2), and Yates (3).General GeologyA recent review of the regional geology and an extensive bibliography of the Sudbury area can be found in the two papers by H. C. Cooke (4, 5). Some of the recent related references are: Jas. E. Thomson (6), E. M. Abraham (7), Franc. R. Joubin (8), W. G. Q. Johnstone (9)."

Jan 1, 1949

By S. B. Ballantyne, D. R. Boyle

"Detailed studies have been conducted on the dispersion of uranium in stream waters and sediments around various types of mineralization and hitherto unexplained anomalous areas in the Okanagan Valley and Highland region of south-central British Columbia. These studies were part of the jointly funded and planned Federal-Provincial Uranium Reconnaissance Program of the Geological Survey of Canada and the British Columbia Ministry of Energy, Mines and Petroleum Resources. Statistical analysis of regional data indicates that U in stream waters and sediments varies considerably for different rock types, thus affecting data interpretation. In addition, the data demonstrate a poor correlation between U in stream waters and their associated sediments which can be largely accounted for by variations in climate and water and sediment composition. Regional trends in the distribution of U can be explained in terms of the above secondary factors as well as primary metallization phenomena.Significant correlations between U and F, and U and Mo can be explained by certain magmatic and mineral-forming processes. U shows little correlation with other base metals.The dispersion characteristics of U in the vicinity of Miocene "" basal type "" mineralization ; uraniferous pegmatite terranes, anomalous lineaments in granitic terranes and high-background volcano-sedimentary areas are discussed. Highly anomalous U concentrations in waters and sediments may not always be indicative of mineralization, and guidelines for interpretation require a sound knowledge of the geological and secondary processes operative in the area."

Jan 1, 1980

By Helen Morrison, Chris Staun, James Vaughan

"Mercury is introduced into the Bayer refining process as a trace element in bauxite. During the digestion stage, a portion of the mercury is extracted which partitions between the flash tank off-gas, vapour condensate and bauxite residue streams. A technology or treatment that stabilises mercury in the solid phase during digestion would prevent environmental management issues that may arise from the presence of mercury in condensate and non-condensable gases. This study examines the effect of process additives on the deportment of mercury under Bayer digestion conditions. Bauxite digestion experiments were conducted in batch autoclaves in the presence of additives. Process liquor was analysed for mercury content using a thermal desorption technique. Pyrite and copper hydroxide were evaluated for their suitability as additives.INTRODUCTIONMercury is an ancient metal characterised by electrochemical nobility, volatility, low solubility in water and a liquid state at room temperature (Holleman and Wiberg, 2001). The biogeochemical cycle of mercury is complex. Elemental mercury may enter the atmosphere due its volatility, where it can be transported long distances. After settling and adsorption to sediments, methylation is catalysed through microbial metabolism (Qureshi et al., 2009). Methylated mercury species are potent neurotoxins, and bioaccumulation of mercury is well documented, particularly in seafood (Kozin et al., 2013, Pan et al., 2014, Pollman, 2014). Environmental regulations for mercury emissions are becoming increasingly stringent (UNEP, 2015). Considerable research has already been performed and technologies developed for the remediation of mercury in wastewater and the trapping of mercury from industrial stack emissions. Wastewater technologies usually target ionised mercury using adsorbent, ion exchange and complexation mechanisms (Krishnan and Anirudhan, 2002, Li et al., 2015a, Chiarle et al., 2000), while stack emission technology is dominated by impregnated activated carbon adsorbents (Gao et al., 2013, Zheng et al., 2012). Related developments include piezoelectric amalgamating sensors for in line detection of gaseous elemental mercury in industrial stack emissions (Kabir et al., 2015, Sabri et al., 2011). There is a paucity of research regarding removal of mercury from the Bayer process."

Jan 1, 2016