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By T. S. Golosinski

Typical dragline rigging includes several sets of ropes: hoist ropes, drag ropes, dump ropes and boom suspension ropes. The drag and hoist ropes contribute most to the dragline operating cost, and significantly influence dragline productive time. Both work in very difficult conditions and wear out rapidly. As a result frequent rope changes are required at a substantial cost and time loss to the operation. Although performance of rigging has a profound impact on dragline performance, there are no industry-wide standards related to its selection, operation and maintenance. Little information on the subject is available and the practice differs widely throughout the industry. The life of drag and hoist ropes depends on: (1) rope construction, which should closely match requirements of the specific application, (2) correct definition and application of the rope discard criteria, so that full advantage of the rope can be taken without endangering safety of operation, and (3) rope operating conditions and its maintenance. The study presented in this paper was intended to address the above points, based on a survey and assessment of the present industry practice.

Jan 1, 1993

By T. A. Toney

A sampling program was conducted in 2008 to determine the run of mine characteristics of 5 coal seams. The sampling program included size analyses and float sink determinations. The samples were analyzed for ash and mercury concentrations for each size and gravity fraction. This paper will report on the sampling program, the analytical results, and the correlations determined in the data set investigated.

Jan 1, 2010

By P. A. S. Manning

Eastern Jamaica consists predominantly of non-carbonate rocks reaching elevations of over 2200 m. The area is drained by a well established river network which supplies close to 30% of the sand and gravel used by the building and construction sector. Present high extraction rates and slow rates of replenishment will result in early exhaustion of this source of aggregate. A number of volcanic and carbonate rocks are being examined as a possible source of high quality aggregate which meet the requirements for all types of construction. Preliminary evaluations show a dacitic deposit to be the most suitable source for aggregate use.

Jan 1, 1998

By E. Pizarro

Division Andina has considered in its long range planning, the exploitation by panel caving method of "Third Panel" mine, which was started its production stage during the second half of 1995. This mine has two production levels, the first is grizzly level and another is L.H.D. level. Both sectors use the same haulage level where mineral is recollected through ore pass. For mineral loading and haulage its use 50ton diesel trucks combined with electro-hydraulic chutes. The automation has permitted what this operation is carrying out with remote control by driver's truck, in concordance to short range planning.

Jan 1, 1998

By C. Haycocks

The evolution of longwall mining is briefly traced from its inception in England in the 1620's. In the beginning this method recovered 90% of coal with roof closure controlled by packs and walls. Mechanization began with kerf cutting, crude face conveyors, and improved face support. Full face mining was accompanied by the introduction of self-advancing hydraulic supports. U.S. longwalls evolved a retreating system to recover blocks of coal outlined by room and pillar panels. Computer control combined with the most modern technology has greatly increased productivity. Past trends are used to predict future technological directions.

Jan 1, 1997

By Peter N. Calder

The selection of a slope angle for an open pit in rock has often been made without the benefit of a comprehensive engineering study. This is largely due to the fact that the hardware and procedures necessary for such a study have not been available. Recently this situation has been reversed. The application of borehole television and terrestrial photogrammetric devices has made possible the accurate determination of rock joint structure, on which stability calculations can be based. Another important aspect is the evolution of practical methods of conducting in-situ rock joint strength tests.

Jan 1, 1971

By W. Robert Power

Dimension stone includes a wide variety of natural materials that are put to an equally wide variety of uses. It is possible to classify dimension stone according to the end use to which the stone is put or according to the lithology of the stone. Both schemes are used by the United States Bureau of Mines in the annual Minerals Yearbook. The 1969 Yearbook lists 15 specific uses and has additional miscellaneous catagories. The same Yearbook lists five specific rock types or lithologies, and also includes a miscellaneous category. In a short presentation it would hardly be possible to list and define all these categories, much less discuss the evaluation of deposits with regard to all possible combinations. Besides, I am only slightly familiar with some of the uses and their requirements. I have therefore chosen to limit my remarks to some special problems in evaluating dimension stone that is to be cut and finished to specific sizes, tolerances, and finishes for use in buildings and some monuments. This use class is called cut stone in the Minerals Yearbook. In terms of dollar value it is the largest single use category. In 1969 the dollar value of cut stone was $29,122,000 which is more than twice the value of the next largest category. For those of you who are interested in other use applications of dimension stone I suggest that you start with recent articles by Bowles (1960), Currier (1960), and Barton (1968).

Jan 1, 1972

By Ö. Y. Gulsoy, L. Ergün, I. B. Celik

"In this study, the studies to develop a flowsheet for a low grade chromite ore are presented. The existing concentrator had to be suspended due to the decreasing metal prices. The study commenced with mineralogy and liberation profile of the chromite. The valuable mineral is chromite and the major gangue mineral is forsterite together with small amount of brucite and calcite. Heavy liquid tests were performed on different size fractions without any acceptable success. The concentration tests were performed using teetered bed separator (TBS) +shaking table, spiral concentrator+TBS+shaking table for different grind size. Based on the test results, 100% finer than 0.4mm was found to be optimum for grind size. Comparison of alternative circuits showed that the performance of both alternatives would be similar. A flowsheet was designed and operated for as 25 tph trial circuit in the existing plant. The results showed that the performance of the plant predicted was very close to the actual plant data. The paper describes the methodology used, presents the experimental data and actual performance figures.INTRODUCTION Turkey is one of the largest chromite producers in the world. Since 1850, chromite mining found industrial applications and geographically spread along six different regions in Turkey. Although the reserves in these locations are not as rich as the big producers, they are regarded as very valuable due to Cr/Fe ratio in terms of chromite utilization standards (1, 2). In this period, significant portion of high grade (=35% Cr2O3), directly marketable ore deposits have already been produced. According to General Directorate of Mineral Research and Exploration (Turkey) data; 83% of the known chromite deposits of Turkey which makes 242 341 000 tons in total, is consisting from the deposits those have a Cr2O3 grade lower than 10%. Only 5% of the known deposits (13 087 000 tons) has a grade of directly saleable (2, 3). Gravity concentration methods are well-known processes for chromite beneficiation and there are plenty of plants in the world and Turkey using these methods. As different equipment combinations can be used for the same enrichment method, different methods can also be used in combination for plant designs (4). Beneficiation of low grade and problematic chromite ores may lead to use these method and equipment combinations (5, 6). Ore liberation, the grades of Al2O3, SiO2, FeO and Cr2O3 in the obtained concentrate, Cr/Fe ratio, some physical and chemical properties between gangue and minerals (i.e. specific gravity, magnetic property, color, etc.) designate the selection and combination of these methods and equipment (7)."

Jan 1, 2017

By B. J. Arnold

Utility coal specifications usually contain a requirement for a maximum moisture content in order to prevent coal handling problems and to minimize evaporative losses in the boiler. As most coal cleaning processes are water-based, dewatering and sometimes drying steps are required to meet moisture specifications. Screens are often used for dewatering, with centrifuges and filters used to further reduce moisture in many cases. Algorithms to predict the performance of screens were developed for the Coal Cleaning Simulator running under Aspen Plus during a project sponsored by the U.S. Department of Energy and the Electric Power Research Institute. These algorithms include calculations for the size separation and a calculation for moisture content of the oversize product based on particle size and specific gravity distribution. This paper discusses the algorithm for predicting the moisture content of coal dewatered by screens.

Jan 1, 1997

By F. Milton Lewis

In 1977 a paper was presented which reviewed the cost trends in producing copper by conventional processes for five years, 1972 through 1976. In this paper these costs have been updated to include the years 1977 and 1978.

Jan 1, 1979

By Walter R. Lawrence

Newmont Gold Company, formerly Carlin Gold Mining Company, is a publicly owned corporation, 95% owned by Newmont Mining Corporation. Newmont Gold Company has operated gold recovery operations North of Carlin, Nevada, since 1965. Development of the Gold Quarry ore body, 19 kilometers south of the original mine, resulted in the decision to construct gold recovery and ancillary facilities in what is referred to as the Southern Area. Plant No. 2, located 11 kilometers North of Carlin, Nevada, was designed to treat 6350 tonnes per day of oxidized gold bearing ore assaying 2.5 grams per tonne of Au at an average recovery of 87%. Flowsheet development conducted by Newmont personnel resulted in the decision to construct a carbon-in-pulp recovery circuit preceded by two-stage grinding, Detailed engineering was done at Toronto by Bechtel of Canada beginning on January 1, 1984. Actual construction began on March 1, 1984, and was completed in June, 1985. First feed was run on June 22, 1985.

Jan 1, 1987

By Daniel Amponsah-Berko, Palas Kamlakar Borkar, Kwabena Boafo, Neha Sharma, Timothy Eisele

A series of iron-leaching experiments were conducted to test the ability of metal-reducing anaerobic organisms to reduce iron from Fe3+ to Fe2+ to dissolve it from iron ore tailings. This bioleaching process involves the fermentation of biomass from Typha latifolia (a common wetland plant) to generate organic compounds, which, along with metal-reducing organisms, reduce and dissolve iron. The concentration of dissolved iron over time was studied for one year. Iron concentration above 1150 mg/L was achieved at a pH range of 3.95–5.36. Tailings from multiple locations were examined.

Feb 1, 2025

By Cuthbert Musingwini, Adeodatus S. Nhleko, Mahlomola I. Mabala

Optimization of a three-dimensional (3D) underground stope layout is complex given the number of variables and constraints to consider, such as the stope size. Determination of the appropriate stope size in stope layout optimization problems is a complex process that must consider several factors including placement of infrastructure and development, production scheduling, and equipment selection. An inappropriate stope layout can result in unrealistic expectations for a production schedule, consequently negatively affecting the derived economic value. Therefore, this paper used a dual interchange algorithm (DIA) to evaluate the effect of stope size on the stope layout economic value (SLEV) for a synthetic Platreef mineral deposit planned for extraction using sublevel open-stoping. The results showed that generally as the stope size increases, the SLEV decreases. This aligns with practical mining because larger stope sizes have a higher chance of incurring more dilution which reduces economic value, while smaller stope sizes enable more flexible extraction where unprofitable blocks can be left unmined as waste, thus increasing the derived SLEV.

Jun 25, 2023

By John P. Weir

The coal industry is ever changing. This paper discusses some of the problems which must be faced and the projected economic effects. Challenges include a relatively mature technology, a resource base which has deteriorated significantly in some areas, rapidly escalating freight rates, and a constantly changing regulatory environment, wherein reduced sulfur emissions will probably be required.

Jan 1, 1984

By H. Y. Yang, L. L. Tong

Semicontinuous-flow, multistage biooxidation experiments of a Chinese refractory, high-sulfur gold concentrate were conducted with different pulp densities for gold recovery. The maximum iron, sulfur and arsenic oxidation rates of 90.0, 88.8 and 96.4 percent, respectively, were obtained in the experiments with 5 percent pulp density. The highest gold and silver recoveries of 96.1 and 68.9 percent, respectively, were achieved by cyanidation. The negative effect of high pulp density on biooxidation was related to the decrease of free and adsorbed cell concentrations with increasing pulp density. The data of iron oxidation from the semicontinuous biooxidation experiments were best fitted by a shrinking core model in which the chemical reaction controlled the rate. The dissolution kinetics of sulfur and arsenic were therefore analyzed by a shrinking core model in which the internal diffusion controlled the bioleaching rates. For the quantitative description of biooxidation efficiency, two parameters — mass dissolution rate and volume dissolution rate — were proposed. In the first stage, the mass dissolution rates of minerals were negatively correlated while the volume dissolution rates were positively correlated with the actual pulp density. The iron and sulfur mass dissolution rates decreased with increasing actual pulp densities in the third and fourth stage, while linear increasing relationships between the volume dissolution rates of minerals and the actual pulp density were observed from the second to fourth stage. The highest mass dissolution rates of minerals were obtained in the first stage with 5 percent pulp density. The highest volume dissolution rates of minerals were obtained in the first stage with 15 percent pulp density. Compared to the volume dissolution rate, the mass dissolution rate was more intuitive to reflect the negative effect of high pulp density on biooxidation efficiency.

By Son Hoang Nguyen, Thanh‑Hai Pham, Duoc Van Tran, Dung Thi Kim Nhu

Apatite ore plays a critical and irreplaceable role in fertilizer production and is being upgraded in quality in northern Vietnam. The old tailing of the Bac Nhac Son beneficiation plant (Vietnam) has a significant apatite amount in the form of coarse unliberated particles. These millions of tons of tailing ore have 6–8% of P2O5 content, which can be retreated to provide fertilizer factories. This work presents the results obtained in recovering apatite from this tailing in the laboratory. By the combination of the processes of classification, preliminary flotation, re-grinding and cleaning in the flotation column, an apatite concentrate of 30.68% P2O5 can be obtained with the total recovery of 37.76% from the initial tailing of 7.56% P2O5. The study results not only provide an appropriate technical solution for recovering the apatite ore from tailing ore but also have outstanding meaningness in the recovery of mineral resources under the context of a circular economy.

May 24, 2023

By K. Neumann

"INTRODUCTION For many automation and safety tasks in open cut and underground scenarios it is crucial to have highly reliable distance measurements at hand. These measurements can for instance be used to obtain the exact position of a machine in one-, two- or even three dimensions. Research and development has shown interest in the ultra-wide-band technology (UWB) in recent years. While for this technology short range, high speed data transfer is the current main research focus, the technology can also be used for highly accurate ranging applications. Due to the use of a very wide frequency band, it is robust against disturbances of many types (e.g. EMC, rain, dust etc.) and is therefore attractive for the use in mining applications. The wide frequency band also offers benefits for ranging applications. Especially in environments with strong multipath problems such as in underground mines it is possible to focus on the dominant signal propagation path, thus increasing the reliability of the measurements. [1] State-of-the-art UWB ranging equipment claims precision within the range of a couple of centimeters and working ranges of more than hundred meters. At the Institute for Mining and Metallurgical Machinery (IMR) at RWTH Aachen University in Germany a modern UWB system was examined in several laboratory and real life tests to examine the feasibility of UWB bases ranging equipment in mining applications. UWB TECHNOLOGY The term ultra-wide-band denotes radio systems that use an ultra-wide frequency band. A common definition for UWB radio systems is that it needs to work on a frequency bandwidth of more than 500 MHz or a bandwidth equal to 20% or more of the center frequency [1]. Due to the ultra-wide frequency bandwidth UWB systems overlap the frequency spectrum of narrow band radio technologies like Wi-Fi, Bluetooth and other mobile communication systems which use a defined carrier frequency onto which information is modulated on (e.g. by using frequency or phase modulation). In order to not conflict with these other radio applications, it needs to be ascertained that the transmission power of a UWB system on a given frequency is so low that narrow band systems are not affected by it. As opposed to this only a small fraction of the UWB system’s bandwidth is affected by the narrow band system. The unaffected remaining bandwidth is sufficient to reconstruct the original signal, even if additional noise is present. Figure 1 shows the power spectral densities of popular radio standards [6], [7], [8]. A significant driver of research and development of UWB systems has been wireless high bandwidth communication. Using an ultra-wide frequency band is highly desirable here, as the channel capacity is dependent on the bandwidth. So far systems have been realized especially for short distances (e.g. wireless USB or Wireless HDMI) but beyond that, communication systems for long distances (several kilometers) are possible [2]. Advances in semiconductor technology led to a reduction in power dissipation of such systems. This enabled higher integration levels which in turn facilitated smaller solution sizes for space constrained applications [3]. Nowadays, UWB is also used for high-precision ranging applications [4], [5]."

Jan 1, 2015

By K. R. Miller

Thunder Basin Coal Company has two mines located in the southern portion of the Powder River Basin. 60-90 km southeast of Gillette, Wyoming. The mines are principally located on federal coal leases acquired in the late-1960's. Development plans for the Black Thunder Mine focused on dragline stripping, but environmental considerations during the mid-1970's made truck-shovel stripping the method of choice when the mine opened in 1976. In 1981, the Coal Creek Mine opened as the first dragline mine in the Gillette area of the Powder River Basin. The regional terrain is flat-lying with occasional clinker-capped hills. The mines are located on the Wasatch and Fort Union Formation contact. The coals are Paleocene in age and the deposits are structurally simple, dipping gently to the west. The seams are thick and are classified as sub-bituminous-C. The Black Thunder Mine, with its 21 m thick seam, is strategically located in the center of the highest heat value mining area of the southern Powder River Basin.

Jan 1, 1993

By Ivano Andreis, Georgios Kalamaras, Mario Liti, Sebastiano Pelizza, Filippo Avesani

"THE SS640 AGRIGENTO-CALTANISSETTA PROJECT The Caltanissetta tunnel is part of the works for the construction of the second 28km-long maxi section of the SS 640 motorway of Porto Empedocle, from km 44 to the junction of Imera in Sicilian hinterland. Amongst other major infrastructure works, the €740 million ANAS (Italian national roads and highway administration agency) project consists of four twin tube tunnels three of which are being excavated by conventional means. The longest tunnel, underpasses the Caltanissetta city and has a length of 3.9km under a maximum overburden of 120m. The JV consisting of CMC of Ravenna and TECNIS SpA won the design & built tender in 2010. Construction started in early spring 2012 following the approval of detailed design and later on the approval of design for construction. THE CALTANISSETTA TUNNEL The Design Phase Tender design and detailed design foresaw the construction of 13.4m excavation diameter tunnels that were to be enlarged in a second phase to create, every 600m, 50m-long tunnel sections for emergency parking. During the design for construction project phase the JV proposed to replace the 13.4m tunnel with a 15.08 excavation diameter that incorporated apart from the two 3.75m wide lanes a 3.25m wide continuous emergency lane. This significant tunnel section modification was associated with better road safety conditions, simpler and safer construction procedures, better statics for the tunnel section while in terms of overall cost the solutions were equivalent.Geologic context The tunnel is located in the middle of the geologically known Caltanissetta basin that is intersected by various tectonic structures. The geologic context for the tunnel scale, was defined in collaboration with the University of Catania in early project phases. For almost its entire length the tunnel is excavated in the Terravecchia formation that represents the lower part of the stratigraphic sequence that was formed in the Tortoniano period of Miocene. The quite complex geological model is also characterized by the presence of the so-called Trubi formation that consists of clay and marl clay. Almost 90% of the tunnel traverses formations that are quite similar in terms of excavation behavior. Exception to this are thrust zones and a calcareous stretch of the alignment. This last segment has a length of 200m and was identified since the very beginning as a tunneling challenge due to the combination of very poor geotechnical properties and an important water load."

Jan 1, 2016

By J. L. Carr, A. K. Smith, C. C. Jobes, G. T. Homce

"Underground continuous mining machines pose a difficult safety challenge since their operators generally work in close proximity to these machines in very restricted spaces. Intelligent software for use with magnetic proximity detection systems has been shown to accurately locate workers around mining machinery in real time. Calibrating these systems requires the manipulation of a lot of data to determine the calibration constants. Researchers have developed software to analyze, convert, and visualize data acquired during this calibration process to more accurately model magnetic fields and their interaction with the environment. This paper details the background, development, and operation of the resulting application software focusing on the utility of the graphical user interface to visualize the magnetic field calibration data. The refined data developed by this process can then be utilized by the proximity detection system to more accurately identify the location of miners working in an underground mining environment. INTRODUCTION Roughly half of the electricity consumed in the United States is produced with coal, and roughly one-third of all US coal production comes from underground mines [1]. Over the last century underground mining health and safety has seen a continuous and dramatic improvement. However, machine-related injuries and fatalities continue to be a major safety concern [2]. Every year, hundreds of miners are severely injured while operating underground mining equipment, and 39 miners have been killed in striking/pinning accidents involving continuous mining machines (CMMs) since 1984. CMMs, such as the one shown in Figure 1, are large mobile machines that are used to mechanically cut coal in an underground mine. These machines weigh approximately 40 to 50 tons, have hydraulically articulated appendages, and are capable of moving at speeds up to six feet per second [3]. Modern CMMs are remote-controlled, yet the operator and other miners are often in close proximity to the machine. Recent research by the National Institute for Occupational Safety and Health (NIOSH) reveals that the locations workers take relative to the CMM are usually influenced by visibility requirements and safety concerns [4]. The Mine Safety and Health Administration (MSHA) estimates that at least 28 fatalities involving CMMs since October of 1984 may have been prevented with proximity detection technology [5]. MSHA further estimates that proximity detection could prevent 20% of all deaths throughout the industry [6]."

Jan 1, 2016