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By Frederick C. Pearson, Albert Brown, Emil R. Ermert

EARLY in 1946 the Shen-Penn Production Co., a subsidiary of the Philadelphia and Reading Coal and Iron Co., was organized to operate the Shenandoah Stripping, one of the largest open-pit anthracite mines in the world. This mine is located in the Western Middle Field near Shenandoah, Schuylkill County, Pa., and involves the removal of approximately 60,400,000 cu yd of overburden to permit the recovery of 9,200,000 gross tons of rough cleaned coal from an area 8000 ft long and 2700 ft wide, with a maximum depth of 400 ft. Operations began in August 1946, and within the next few years 31,811,000 cu yd of overburden and 2,994,000 gross tons of rough cleaned coal had been removed. During the early days of open-pit mining operations, steam was the primary motive power. However, as the size of the equipment increased, so did the problems of fuel, water, labor, and maintenance. Because of its efficiency and convenience, electric power rapidly replaced steam. Later the modern diesel engine was developed, and today practically all stripping equipment is either electric, diesel-electric, or diesel-powered. In locations where electric power is not readily available or where operations are scattered over a large area, diesel power is favored. At Shenandoah operations are highly concentrated in a relatively small area, and this fact, coupled with the availability of ample electric energy, indicated the selection of electric-powered equipment. Since this was a new company, it was necessary to purchase every item, from the smallest tools to stripping shovels. Although the organization period was hampered by the postwar scarcity of materials, an excellent opportunity was afforded to set up a thoroughly modern plant. This paper will describe the power facilities, with particular emphasis on the more unusual features. The substation is a major item in a power distribution system, and a simple arrangement utilizing high quality equipment is an excellent investment. With this in mind, a 3000-kva unit type substation was selected and installed. This unit is made up of three sections, which are assembled simply by bolting together the various sections and connecting the power leads, see Fig. 1. The transformer proper, rated at 3000 kva, is oil-filled and nitrogen-sealed, having a 66,000-v Delta primary and 4160-v Wye secondary with a grounded neutral and 46-ohm ground resistor. The function of this resistor will be described later. Electrical energy is purchased from a public utility and is delivered to the main substation at 66,000 v over one or the other of two incoming lines. These lines terminate on a high voltage switching section on which high voltage fuses and Thyrite lightning arresters are installed. The outgoing feeder switching unit is made up of the following: 1-An auxiliary compartment consisting of potential and current transformers with necessary terminal blocks for connecting to power company metering equipment. 2-Another auxiliary compartment containing a control transformer, battery, and battery charger for the furnishing of power for tripping and reclosing of power circuit breakers. The assemblies in these auxiliary compartments are mounted on carriages that can be rolled in and out with ease. Potential transformers are readily accessible for inspection and fuse replacement. When withdrawn from the operating position they are completely de-energized and grounded. 3-Two feeder breaker compartments, each with a 1200-amp, 5000-v, solenoid-operated magneblast air circuit breaker, voltmeter, ammeter, overcurrent relays, and a ground relay. These power circuit breakers can be quickly and safely withdrawn or repaired. A built-in isolating mechanism is used for lowering the breaker to a transfer truck for repair or inspection or as a means of disconnecting the breaker from the source of power as an added precaution when working on power lines. Thus inspec-

Jan 1, 1952

By Geo. A. Murphy

MR. ARTHUR E. GIBSON (General Manager, Consumers Mutual Coal Company of Utah) : I suppose the reason I was called upon to read this paper was because I was at the mine for several years, but I have not been there for the past four years and the installation has been put in since I left. This article has been written by my successor-it follows: At the very urgent solicitation of your Secretary I have consented to prepare this paper descriptive of the spiralizing plant which is a part of the new steel tipple recently erected by the Spring Canyon Coal Company to serve its mines at Spring Canyon, Utah. I have been reluctant in giving this consent for two reasons: one of which is an excellent one, and the other isn't any good at all. First,, I find that it takes a long time to become familiar with the eccentricities of spirals-to get wise to their whims and peculiarities, and while this plant has been in operation for a number of months, something new seems to crop up nearly every time I see it, and -it would be impossible to describe all of these things even if I remembered them. The second reason is, purely personal. Among the many things I have learned by attending the sessions of the Rocky Mountain Coal Mining Institute is that if a man is not pretty sure of the ground he attempts to cover, he had better keep his mouth shut, because if he isn't right, he is dead sure to be called down by someone. However, as I will not attend the session, this feature will not hurt much, but it will make it necessary for someone else to read the paper and this will make it much better for those who are obliged to listen to it because I don't read English very well. To begin with I will say that what is said in this paper applies only to the plant under discussion as I have had no experience with any other plant. While spirals have been in use for quite a number of years, and there are some large plants in the East, their use has not been general, and I believe the plant at Spring Canyon is the only one in the United States west of the Mississippi River. The details of the plant were worked out by Mr. Thos. R. Stockett, General Manager of the Spring Can= yon Coal Company; it was manufactured by the Anthracite Separation Company of Hazelton, Penn., incorporated in the design and erected by the Link-Belt Company of Chicago, in connection with the balance of the tipple. It consists of five units. Each unit consists of a vertical wood column about 6 inches in diameter, and 9 feet 6 inches in height, around which the spiral is built. It is something like a triple screw conveyor, set vertically, with flights down which the coal and refuse travel by gravity in the process of separation. There are three of these flights, forming a sort of nest but about 7 inches apart, and they make 21 turns around the column in its length. These flights dip toward the column about 27 degrees; they have a uniform pitch downward of 31 degrees; they are 19 inches wide at the top (measured from the column) and taper gradually until they are about 9 inches at the bottom. They are not made with one continuous plate from top to bottom, but are made up of a number of plates. Some of these plates are slightly waved, others have small corrugations in them and still others are perforated with small holes, all of which are intended to accelerate or. retard the movement of the coal and refuse as they pass down, At intervals there are adjustable plates in the flights for the purpose of decreasing the maximum outside;

Jan 1, 1926

By E. H. Cho

INTRODUCTION Activated charcoal has been used for several centuries in many capacities including the recovery, isolation and purification of various materials (1). The first use of charcoal in a gold metallurgical system was in the extraction of gold after chlorination (2, 3,4). The gold was dissolved in a chlorine system and subsequently filtered through charcoal. The application of charcoal with cyanide extraction was patented by Johnston (5) in 1894 and adopted commercially in Australia in 1897. The process consisted of dissolving the gold and silver in a potassium cyanide solution and passing it through a series of charcoal filters. The charcoal was subsequently smelted to recover the gold and silver. The interest in the use of charcoal diminished in the first part of the twentieth century as the practice of the use of zinc as a precipitating agent increased. However, in 1916, the Yuanmi Mine in Australia replaced their zinc precipitation plant with a charcoal adsorption plant. In 1926, Scott and Gross (7) of the U. S. Bureau of Mines con- ducted extensive research on the adsorption of gold and silver from cyanide leach solutions. Among their findings was the result that the most important factor in improving the adsorptive power of charcoal was heat treatment with oxidation by air or steam. The work of Zadra (8) in 1952 stimulated renewed interest in the use of activated charcoal in gold and silver recovery with the development of a method of recovery of the gold and silver from the charcoal other than its destruction by burning. The process involved simultaneous desorption

Jan 1, 1983

By Tony S. Calayag

Throughout the mining industry today, new bearing materials - ZA* high-performance zinc-aluminum alloys - are reducing costs of maintaining and rebuilding a wide range of equipment. As replacements for bronze bearings, installed in original equipment at the plant or during maintenance and repair operations in the field, the zinc alloys frequently provide better or equal performance at lower cost. The ZA Alloys The ZA alloys are a family of three high-performance zinc-aluminum alloys that compete in cost and performance with cast iron aluminum and bronze. The growing number and uses testifies to the versatility of these alloys and is encouraging their consideration in a wider range of applications. The ZA alloys are referred to as ZA-8, ZA-12, and ZA-27, the numbers corresponding approximately to the percentage of aluminum each alloy contains. ZA-8 is a permanent-mold casting alloy and is usually selected for decorative purposes; ZA-12 provides both performance and cosmetic benefits; ZA-27 offers the greatest functional strength. The term high performance ZA alloys distinguishes them and their improved engineering properties from traditional zinc die casting alloys. Maintenance Savings At its mine in Timmins, Ontario, Kidd Creek Mines Ltd. operates over 40 Joy VCR- 150 crawler-mounted air-powered rock drills. Most of the drill components undergo severe stress as the drill batters through the under-ground rock. As the components wear, the drill bits wobble; when the wobble becomes excessive, the drills are rebuilt. In the gear train, which rotates the drill steel, there are three planetary gears with - historically - bronze bushings. Since the planetary gear bushings are wear items, they are routinely replaced during overhaul. The bronze planetary gear bushings (three bushings per assembly) were replaced up to five times annually. With 43 drills in use, bushing consumption approached 600 per year. At the manufacturer's replacement part cost, the 600 bushings and gears would cost more than $20,000 a year. Even though a major saving was achieved by having the bronze bushings manufactured locally, the 600-unit annual usage provided ample incentive to investigate other ways of lengthening drill life and reducing the part costs. One approach was to consider using a bushing material that offered good bearing properties, but was lower in cost. About three years ago, ZA-12 zinc-aluminum casting alloy, costing less than half as much as bronze, was evaluated and selected for testing. One hundred ZA bushings were manufactured and placed in service as the drills came in for rebuilding. At the next rebuild the "drill doctor" (drill maintenance mechanic) noticed that, although the bronze bushings were completely destroyed, on occasion the zinc alloy bushings were not. In addition, he noted that some of the ZA bushings showed less wear than the bronze bushings. Because the bushings were changed routinely during each overhaul, the actual operating life of each bushing was not determinable. Therefore, it was not possible to statistically compare the life of the ZA bushing against the bronze. However, the desired life of the part was from overhaul to overhaul. So the ZA alloy obviously met the objective, giving equal or better life than bronze at a significantly lower price. Based on the favorable results of the testing under actual operating conditions, Kidd Creek maintenance personnel decided to switch permanently to the ZA bushings for rebuilding the VCR-150 rock drills. Original Equipment Application As one of the leading companies marketing the ZA alloys, as well as a zinc -copper-silver mining company, Kidd Creek is interested in developing applications for the alloys by original equipment manufacturers such as joy Manufacturing. Kidd Creek marketing representatives provided joy with information on the Timmins mine tests, along with ZA-12 bushings for evaluation and testing. Based on this information, joy installed ZA bushings in 12 new VCR-150 units and delivered them to customers for use in such areas as granite quarries and copper, lead, zinc, and limestone mines. During the following year, joy engineers closely monitored repair reports to verify the performance of the ZA part. The engineers' findings convinced them of the advantages of ZA-12. As a result, joy now uses ZA-12 bushings in the manufacture of its VCR-150 air tools. Advantages for Casters and Users In the foundry, the new alloys have proved their castability and profit potential in sand and metal permanent-mold processes, as well as the new graphite permanent-mold gravity casting process. The energysaving, pollution-free and ease-of-machining benefits they offer are important to all of these processes. Most recently, the high-performance alloys entered the arena of cold-chamber die casting, where they provide properties beyond those of

Jan 7, 1983

By Tai Luu, Maxim C. Schisler, Yaser Taheri

The Stevens Gateway Project is an expansion of the Stevens Institute campus overlooking the Hudson River in Hoboken, NJ. The plans call for 90,000 ft2 (8360 m2) of new classroom, research, and student life facilities in new, 4-story buildings. The excavations for the building footprints were bounded by city streets and existing buildings, including the historic Carnegie Laboratory of Engineering, built in 1902. Pit underpinning was originally specified for the Carnegie building. However, given the depth of cut, construction time required for the 13 ft (4.9 m) deep pits would be substantial. The geotechnical contractor retained for the support of excavation work therefore offered an innovative active soil nail wall design that would meet project requirements in a shorter timeframe. Unlike the passive soil nail systems common in the industry that are chiefly used for soil slope stabilization, active soil nail walls contain pre-stressed anchor components to resist soil movement and limit settlement of soil and structures being contained. In addition to a discussion of the overall design approach of the active soil nail wall system, this paper will include a detailed description of its constructability and effectiveness. This project’s use of a conventional slope stabilization technique for an unconventional purpose may have positive implications going forward. INTRODUCTION Stevens Institute of Technology is a private university in Hoboken, New Jersey that sits on the cliffs of the City of Hoboken overlooking the Hudson River and Manhattan Island to the east of the campus. In recent years, the university has executed numerous plans to expand and upgrade its campus academic, student life, and residential facilities. One such project is the Academic Gateway Complex. The plan adds 90,000 ft2 (8360 m2) of new classroom, research, and residential facilities while also enhancing community connections by building a park to serve as a green corridor for the city. The proposed construction took place on the north and south side of 6th Street between Hudson Street and River Street. The project included the demolition of an existing university building followed by the construction of two, 4-story buildings on the north and south property lots. The north and south buildings will be connected by a second floor bridge spanning 6th Street. The buildings each contain a full basement extending from the proposed ground floor at approximately El. 41ft (12.5 m) to the basement subgrade at El. 26 ft (7.9 m). Each building will be constructed on respective mat foundations. Figure 1 presents an overview of the project area.

Jan 1, 2019

By Batric Pesic

Dissolution of gold with elemental bromine was studied by using a rotating disc technique. The main parameters studied were: bromine concentration, stirring speed, pH, and temperature. Additionally, effect of copper, iron, and manganese was also examined. A special attention was paid to elucidate the role of cations, primarily Na+, during gold dissolution. It was found that gold dissolution with bromine was characterized with two pH regions. Below pH=7, gold dissolution was independent of pH, and above this value, gold dissolution decreased with pH increase. Gold dissolution rates were proportional with concentration of bromine. Two regions, diffusional and kinetic, were observed with respect to stirring speed. with respect to the role of Na+, and cations in general, they play absolutely no role during gold dissolution with bromine, unless they are in their lower oxidation state and become oxidized by bromine. In that case they have a negative effect because of bromine consumption.

Jan 1, 1991

By A S. Derrington

There are several long-standing rules of thumb that are often quoted in mine ventilation studies. They include airway ‘carrying velocities’ and the critical upcast air velocity range that must be avoided to prevent a water blanket forming. Quoting these rules of thumb may lend an air of legitimacy to a ventilation design, and allow the design engineer to avoid having to study a problem from first principles. But how valid are these shortcuts in today’s rapidly changing world? This paper summarises research into the genesis of several commonly quoted rules of thumb. It finds that they were very specific to the local conditions, practices and economics at the time they were developed. It also presents examples where applying these rules of thumb outside of their original context can lead to unexpected and erroneous results.CITATION:Derrington, A S, 2017. Ventilation rules of thumb – friend or foe? Focusing on design upcast air velocities for shafts and raise bores, in Proceedings Australian Mine Vent Conference 2017, pp 253–260 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By B Howard, M Jones, D Pershke

"Current closure objectives and criteria are often difficult to achieve and are not delivering value for money outcomes at closure. Current mine closure processes tend to focus on rehabilitation and revegetation of landform structures to as close to premining condition as possible, rather than focusing on the functions of those structures and values they provided. Because mining has highly disturbed the environment, premining conditions and vegetation are often not achievable and objectives and criteria aimed at achieving close to these conditions have been shown to be very costly.The authors have developed a broader approach to developing mine closure plans that is based on environmental risk and gaining post-closure social, environmental and economic value. We think the focus should shift from trying to return the original landscape to returning functions and values provided on- and off-site. If it is not possible to return values on-site in a cost-effective manner, investment should be provided to deliver equivalent values elsewhere.This process can provide better stakeholder acceptance, deliver better environmental outcomes on the tenement and within the catchment and significantly reduce costs, whist fulfilling closure obligations.This framework should enable closure teams to: focus on the functions and services that are important to achieve as outcomes post-closure, rather than a focus on revegetation and replacing the premining biophysical structure engage meaningfully with stakeholders regarding closure outcomes and link outcomes to stakeholder values conduct transparent option evaluations that enable stakeholders to clearly understand the costs and benefits associated with each option and to participate in dialogue on option selection.We present examples of how the framework could be applied to identify alternate closure options that achieve equivalent value outcomes while reducing the costs of closing the mines.CITATION:Howard, B, Pershke, D and Jones, M, 2014. Achieving better mine closure outcomes for less money, in Proceedings Life-of-Mine 2014, pp 615–620 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 16, 2014

By R. Elliott, H. Bayati

"Effect of time and temperature on microstructure and mechanical properties of an austempered ductile iron, ADI, of composition 3.6%C, 2.6%Si, 0.4%Cu, 0.2%Mn are reported. Xray analysis and. microstructural observations indicate that lowering the working temperature, aging temperature, increases the lifetime of ADI significantly. Results show· that lowering the aging temperature increases the strength and reduces the ductility of ADI. DSC traces for ADI austempered at 340°C are presented. Comparison of the DSC analysis and kinetic measurements demonstrates that the DSC traces can be· used to predict the life time of ADI successfully.IntroductionAustempered ductile iron, ADI, is one of the most significant developments in cast iron technology over the past two decades. Outstanding properties of high yield, ultimate strength, ductility, fatigue and wear· resistance make ADI suitable for a range of applications including gears, connecting rods, crankshafts and agriculture machine components. The austempering reaction in cast iron occurs in two stages, Fig. I, in contrast to the single stage reaction in steel. In stage I the relatively low carbon austenite produced during austenitising transforms into ferritic plates and high carbon austenite, a metastable structure called·ausferrite. The high carbon ailstenite and supersaturated ferrite produced in stage I decompose into ferrite and carbide in stage II: to form a structure similar to the bainitic structure in steel. This behaviour exposes a well-defined processing window, t1 - t2, over which the maximum amount of ausferrite is produced, Figure 1. Whereas the bainitic structure determines the properties of austempered steel, ADI properties are mainly affected by volume fraction of retained austenite (VRA), austenite carbon content (ACC), unreacted or martensite volume fraction (UA V), compositiori and amount of carbides, and morphology of ferritic plates[l,2]. Due to the detrimental .effect of martensite and carbides on properties of ADI, an ideal structure of ADI consists only of ausferrite [l,2]. Thus, it is common to determine the processing window for each austempering treatment in order to identify the optimized austempering time. Decomposition of austenite (stage II) signals the end of the life time for an ADI component, therefore, the aging behaviour of ADI at different working conditions can be studied by determining the t2."

Jan 1, 2000

By S S. Kanchibotla, E J. Sellers, L Julian, A Musunuri

Fume events in coalmines are typically associated with wet conditions, soft ground and deep holes. An ACARP research project used laboratory and field testing combined with literature reviews, numerical models and field investigations to characterise the influence of these conditions on the propensity for fume. This paper highlights the results for soft ground and wet conditions and proposes a proactive fume mitigation methodology. A simple numerical model is used to show how fume arises in soft rock that yields more under the loading of high-pressure, water-resistant explosive blends than for ANFO. The blends cool more rapidly after detonation into the lower temperature zone favourable for NO2 production. Low-pressure, high detonation temperature explosives are loaded or charged into soft ground. Water resistance must be considered because soft, faulted and fractured ground can lead to fume from degradation by water flow and non-ideal detonation of product in cracks.A suite of tests were developed to quantify ANFO and emulsion blend performance over time that can be carried out in a mobile laboratory on-site. Index tests such as viscosity measurement and water resistance in beakers are proposed to quantify long-term product performance because small components, such as surfactant, prill impurities and prill fines, contribute to inconsistent product performance. Water ingress experiments and detonation tests aligned with field investigations identified and characterised the role of groundwater in damaging ANFO and causing fume.Fume risk management is achieved using a proposed proactive fume mitigation methodology to characterise influences such as seasonal rain variation, groundwater flow hydrogeology, rock mass strength and structure well ahead of blast design. The design of blasts and selection of explosive products to consider expected conditions will reduce fume, improve efficiency in the mine and offer cost advantages.CITATION:Julian, L, Musunuri, A, Sellers, E J and Kanchibotla, S S, 2015. Mitigation of post-blast fume in soft ground and wet conditions, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 511–518 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By Ernest Baafi, David Drew

Microsoft Excel based ultimate pit limit (UPL) optimiser has been developed to determine the greatest economic value of an orebody. UPL manipulates a given geological block model to define an ultimate pit limit using either the moving cone, method or Korobov algorithm or Lerchs-Grossman technique. UPL is designed to be an adjunct to MS Excel; the cells in Excel are excellent analogue to the blocks in a geological model, providing X-Y dimensions in an easily viewable and editable state. The use of individual worksheets within an Excel workbook provides the necessary depth to a 3-D block model.

Jan 1, 2002

By Stavros H. Constantopoulos

Mediterranean regions such as Greece, Turkey, Cyprus, Corsica and New Caledonia have experienced epidemics of malignant mesothelioma as a result of non-occupational, ??domestic?? exposure to tremolite asbestos and fibrous erionite. This exposure to tremolite asbestos and fibrous erionite is typified ??domestic?? due to its prevalence in regions with natural deposits of tremolite asbestos (or fibrous erionite) where the material from tremolite asbestos or fibrous erionite is used for domestic applications such as whitewashing. However, these exposures may be useful in examining the potential consequences of even small amounts of amphibole asbestos fibers in the ambient air. It can also elucidate the effects of fibers that behave like amphibole asbestos. However, this type of exposure is not useful for studying the potential effects of small amounts of asbestos in the ambient air of big cities due to the differing nature of the fiber types and modes of exposure between the regions. © 2008 Published by Elsevier Inc. Keywords: Tremolite asbestos; Erionite; Domestic; Environmental; Exposure

Jan 1, 2007

By Arash Saeidi Rashk Olia, Dunja Perić

The increasing demand for renewable energy has attracted attention to energy geostructures as means of extracting clean geothermal energy from the ground. To further advance the understanding of soilstructure interaction in energy piles analytical solutions considering the self-weight of the pile were derived. These solutions were then incorporated in recently-derived thermomechanical weightless solutions to provide comprehensive analytical solutions for axial displacement, strain and stress in single energy piles. This was accomplished by comparing responses of energy pile under different loading scenarios that reflect presence and absence of the self-weight. Results of mechanics-based analysis revealed that the self-weight of energy piles embedded in stiff soils has no significant contribution to displacement, strain and stress that develop under thermo-mechanical loads. Overall, the significance of the self-weight contribution depends on the magnitude of thermal load as well as the soil-pile interface stiffness. The stiffness of end restraints imposed to the pile head and tip were also found to play an important role in contribution of self-weight in induced thermomechanical stresses in energy piles.

Oct 1, 2022

By Xin Zhou, Huilin Jia, Xiaofei Liu, Jinxin Wang, Zifeng Meng, Zinan Du, Hui Xie, Guihang Jiang

The change of gas emission or concentration level at the working face is one of the main precursor characteristics of coal and gas outburst. At present, coal and gas outburst monitoring and early warning are mainly based on whether it exceeds the limit and its change law. However, the gas concentration level is affected by factors such as coal seam gas content, permeability, and mining process, and the change law is complex to recognize manually. In this paper, the response characteristics of gas concentration level in the mining process are analyzed and revealed, and a bidirectional long short-term memory model is established. The change characteristics of the gas concentration level in the mining and non-mining processes are studied and recognized. The results show that the change law of gas concentration in the mining process has apparent periodicity and trapezoidal volatility. The proposed intelligent recognition method based on the bidirectional long short-term memory neural network can automatically recognize the underground mining and non-mining processes, and the recognition accuracy achieves 97.7% . The research can significantly help improve the level of coal mine safety management and the accuracy of early warning of coal and gas outburst.

Apr 29, 2023

By Lourens Scheepers

Mining induced seismicity and rockbursts have been part of the deep level gold mining industry in South Africa for many years. One could be forgiven for thinking that we should know everything there is to know by now to have rockbursting under control to a level that it has minimal impact on safety and production. Well, we don’t… There are things we know that we know, and they are implemented, or should be. There are thigs we know that we don’t know, and they are researched, or should be. There are things we don’t know that we don’t know, and, well, we don’t know… We know that seismicity and the associated potential for rockbursts generally increase with an increase in stress (increase in mining depth and/or mining span and creation of remnants) and proximity to faults and dykes. We know there are a number of potential sources of events in a mine; that is: mining abutments, pillar abutments, mining faces and geological structures (faults and dykes). We know there are a number of event mechanisms associated with these sources; that is: slip on a geological structure, shear through intact rock and bursting of the rock near the edge of a mining excavation. One of the tools used more and more and with increased success to identify event source mechanisms is Moment-Tensor analysis (MT). This typically assist in differentiating between three event mechanism components: volumetric deformation component, axial deformation component and slip / shear component. The insight gained from MT assist greatly in identifying the most likely event source to assist in understanding the rockmass response to mining. We know that the seismic response in our mines are mining induced (not natural). This may seem trivial, but it is important to realise that we influence the seismic response with the way we mine, and by how much we mine (extraction ratio). Therefore we put design rules and strategies in place to reduce the seismic hazard and we install rockburst support in our mining excavations. We know the seismic response to mining is influenced by the properties of the rockmass, including strength, stiffness and brittleness, but quantifying its influence is typically more difficult than expected. We know numerical modelling can improve the engineer’s understanding of the potential rockmass response associated with designed mining layouts and strategies. For our environment (narrow, tabular large area) elastic boundary element modelling remains the most convenient and practical approach, but it overestimates the stress at mining abutments and underestimates the stress further away from these abutments. Adding a crushing (based in limit equilibrium) modelling approach vastly improves the boundary element modelling ability to simulate the deformed (interpret fractured) zones and associated redistribution of stress. We don’t know how to quantify what an acceptable seismic risk is. We don’t know if we can mine remnants at an acceptable seismic risk. Some remnants are extracted surprisingly easy, others serve us with devastating rockbursts. The limit equilibrium modelling shows potential to significantly improve our ability to quantify the rockburst risk. We don’t know if large-scale preconditioning is possible and will be effective to significantly reduce the seismic risk associated with remnant and pillar mining. Research is required (and has been initiated). Vast areas of ground have been extracted historically in the South African gold fields. Most gold reserves are now in deeper ground (4000 m) and historic remnants (areas left before due to mining difficulties) as well as pillars (regional stability pillars). If we cannot find ways to extract these reserves at acceptable risk levels, the future of the South African gold mining industry is very short.

Apr 26, 2022

By Diogo Fonseca, José Manuel, Nuno Fernandes, Blessing Taiwo

This research focuses on enhancing the synergy between blasting and primary crushing operations in quarries. A blast operation at dstgroup aggregate quarry in northern Portugal was simulated to fine-tune blasting techniques aimed at optimizing fragmentation indicators. The methodology involves conducting precise blast drill hole surveys, generating detailed terrain 3D models, and integrating these models into blast simulation software to enhance accuracy and optimize production efficiency. The study applies these simulations to test blasts, evaluating improvements in cost-effectiveness, crusher power consumption, and fragmentation efficiency using both aerial and terrestrial image analysis technology. The quarry key performance indicators (KPIs) guide the blast design simulations, ensuring practicality and relevance. The case study blast revealed that implementing optimum blasting techniques can enhance crusher throughput, reduce operational costs, and improve safety. This paper is part one of a three-part technical series where we aim to create a sampling procedure and establish a reliable baseline for the current state of operation. This baseline will be used in subsequent follow-up technical papers to make recommendations and improvements. The outcome of this study provides a framework for quarry operations seeking to enhance their efficiency.

Jan 21, 2025

By W. O. Karvinen

"In the Timmins area, a close spatial and chronological association exists between gold deposits and two major stratabound carbonate-rich members and related quartz-feldspar porphyries. Synvo/canic and metamorphogenic are the two main types of mineralization recognized. Synvolcanic ores include the stratiform quartz-ankerite ""veins"", pyritic carbonates and chert-carbonate-tuff sedimentary rocks and epigenetic ventrelated breccias and stringer zones. Metamorphogenic ores consist of quartz-carbonate fracture fillings in dilatant zones developed during various phases of regional deformation and metamorphism. They are classically epigenetic in character.The evidence suggests a primary syngenetic enrichment of gold on the ocean floor and in vent areas during submarine felsic volcanism and related exhalative-hydrothermal activity followed by further enrichment into quartz-carbonate stockworks during regional deformation and greenschist metamorphism.Although normally thin (a few hundred metres), carbonate members in Archean volcanic terrain represent intense hydrothermal activity which could have transported and enriched gold. They should be used to locate fossil vents and structurally favourable zones where economic concentrations of gold may be found."

Jan 1, 1982

By W. P. Lass

The purpose of this article is not only to describe the plant and method of cyaniding the Treadwell concentrates, but to present some of the results of the experimental work obtained in the past three years for the Alaska-Treadwell Qold Mining Co., at Douglas Island, Alaska, under the direction of F. W. Bradley, Consulting Engineer, and Robert A. Kinzie, General Superintendent, of the affiliated companies. At the time the experimental work was undertaken the concentrates were being shipped to the smeltery at Tacoma, Wash., and the cost for treatment of 3-oz. (gold) concentrates was $11.95 per ton, divided as follows : Smelting-charges,......... $4.00 Loading, freight, insurance, etc., . 2.89 Interest due to time loat in transit and in settlement,... 0.05 Loss due to settlement for 95 per cent. of the gold at $20 per ounce, 6.01 Total,...$11.95 From the experimental work described later, it was estimated that 96 per cent. extraction could be made by treatment on the ground, and that the cost, when treating 80 tons per day, would be $3.25 per ton, divided as follows : Per Day. Per Ton. Labor,. $86.16 $@.827 Chemicals,.76.60 0.960 Power and steam-heat,... 67.60 0.845 Marketing-, refining- and other charges, . 49.36 0.617 Totals,.. $2.59.72 $3.250 Adding to this total the 4 per cent. treatment-loss, which on 3-02. concentrates amounts to $2.48, gives a total cost of $5.13 per ton. Comparing this with $11.95, the cost when shipping to the smelter, leaves a net gain of $6.22 per ton by the local

Jan 1, 1912

By M. L. Pududu, B. Ceki, K. Mohajane

This study was aimed at determining the effects of industrial action on profitability in the South African platinum mining sector. We compared companies where employees engaged in industrial action (affected companies) to strike-free companies (competing companies). Industrial action refers to strikes by rockdrillers, as these strikes typically result in the shutdown of production at the mines affected. A t-statistics analysis of significant differences in revenue and earnings of affected and non-affected platinum companies was conducted using data from platinum mining companies listed on the Johannesburg Stock Exchange from 2011 to 2015. Contrary to international studies, which suggest that the spillover effects of industrial action positively affect competing companies, our findings show that profits in the platinum sector decrease significantly during strike periods for both affected and competing companies. The results indicate industrial action is a threat to the profitability of all companies, and that employee demands should be prioritized and negotiated before they result in industrial action. Improved dialogue between management, labour unions, and employees in the platinum mining industry is recommended. The study contributes to the scanty literature on the effect of industrial action on the profitability of mining companies in a developing economy.

Dec 13, 2022

By Alejandro Lagos

El modelamiento estructural de una zona es esencial para la búsqueda de zonas favorables para la mineralización. En ese sentido, el presente texto describe la geología estructural de las áreas de Cajamarca, San Marcos y Bolivar y su posible relación con la génesis de los yacimientos de minerales ubicados en ese sector y así diseñar un modelo estructural de las aéreas mencionadas apoyado por el método de mapas paleogeológicos.

Sep 14, 2009