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By Pei‑liang Xu, Jun Wang, Xi Zhang, Deng‑pan Qiao, Tian‑yu Yang

The surface backfill, serving as the operational platform for continuing mining in upward slicing and filling stopes, is required to possess sufficient strength and thickness. Currently, there are limited model methods for determining the strength and thickness of the surface fill body. By analyzing the mechanical actions on the surface backfill, it is determined that its stability is mainly influenced by the combined effects of normal and tangential uniform loads under full-load conditions of trackless equipment. Assuming a circular contact surface between the tire of the trackless equipment and the surface backfill, and utilizing solutions from elastic mechanics theories such as the Boussinesq and Cerruti solution, the stress and displacement distribution of the surface fill body were obtained. Based on the maximum vertical stress condition, where the surface backfill body undergoes maximum deformation while still in an elastic state, and considering the stress–strain relationship, a model for the strength and thickness of the surface backfill has been established. According to the research findings, the design for the strength and structural parameters of the surface backfill has been developed to meet the full-load operation of the Atlas ST7 scooptram, with a compressive strength of 1.32 MPa and a thickness of 0.5 m. Numerical simulation analysis results indicate that the stress and displacement of the surface backfill align with theoretical analysis results. Practical results from industrial application in the western section of the Dahongshan Copper Mine demonstrate that the designed strength and thickness of the surface backfill meet the operational requirements for trackless equipment, resulting in significant engineering application effects and economic benefits. The research findings hold significant importance for advancing the theory of backfill mining and have high applicability and promotional value for similar mines.

Mar 24, 2024

By Ray W. Ballmer

Historically, Bingham is a rail pit, starting with steam locomotives in 1906 and converting to electric locomotives in 1923. Ore production was maintained through an effective utilization of available rail equipment. From time to time as it became necessary to deepen the pit and as stripping ratios increased, various studies were made on alternate material haulage systems. Utilization of diesel locomotives, conveyor belts, and trucks have all been subjects of study, however, conversion from rail haulage utilizing electric locomotives could not be justified. Because of the gradual decline in ore grade, a program was approved in 1963 to raise ore production to 108,000 tons per day. This was designed to return copper production to the 1950 level. Attainment of this production level by expansion of the rail system had definite limitations and built-in inflexibility. Track and trolley wire relocation causes shovel down time in excess of that required for normal maintenance. Instability of the dumps and the resulting additional track maintenance increases greatly as the volume of waste material to be handled daily expands.

Jan 1, 1965

By Aline Tatom

This paper presents numerical and experimen¬tal results dealing with the application of ferric ion oxidation of uranium in acidic media. Conclusions are derived from matching numerical results to experimental data taken on one-dimensional laboratory leaches using ore from a South Texas Coastal plain deposit. Since the numerical results can be made quite general, we are able to extract and quantify the effects of oxidant concentration, flow velocity, mass transfer, chemical kinetics, and competitive oxidant consumers (pyrite and molybdenite) on the experimental results. Our results suggest that the leaching of uranium is a mass transfer controlled while that of pyrite is kinetically controlled.

Jan 1, 1981

By Thomas S. Nye

Mineral exploration in the United States relies heavily on theoretical geologic concepts and indirect methods such as geophysics and geochemical prospecting, as there are few exposed areas of mineralization which have not already been explored at least once. In Mexico ore-grade samples can be cut at the surface on vein, replacement, and disseminated types of deposits in many areas. Here the problem is not in finding a mineralized area but in deciding which mineralized area can be explored and developed at the least risk and cost, and have the greatest profit potential, within the framework of Mexican mineral economics and government policies. Mexico's min¬eral industry is regulated through a system of permits for various phases of mineral exploitation, and by taxes. This regulation and its effects are not unlike those which may be expected in the United States if present legislative and administrative trends continue.

Jan 1, 1972

By B. A. Ashley

Rosebud Mining Co. (RMC) is based in Kittanning, PA. As of October 2013, it operated 24 active underground mines in Pennsylvania and Ohio. RMC?s Tracy Lynne Mine is located approximately 5 km (3 miles) east of Apollo, PA, (approximately 48 km or 30 miles northeast of Pittsburgh, PA) and mines the Lower Kittanning coal seam. The coal seam averages approximately 1.1 m (45 in.) thick and is of steam coal market quality. The mine is a single unit operation. Coal is mined using a continuous mining machine and is transported from the face to the conveyor belt using a continuous haulage system. Typical ventilation in the mine consists of an exhausting fan that draws air through isolated intake, belt and return air courses (Fig. 1).

By Luis Fernandez-Deza, James Hawn, Dustin Mount, Jean-Marc Wehrli

The RiverRenew Tunnel System project in Alexandria, VA forms part of a CSO scheme aimed at reducing overflows of combined stormwater and sewage into the Potomac River during storm events. A major piece of the project is a 12-foot internal diameter tunnel of approximately 12,000 feet length lined with a single-pass precast concrete segmental liner and excavated by an Earth-Pressure Balanced Shield TBM. The tunnel lies between 120 to 140 feet below grade in the clays of the Upper Potomac Formation with occasional dips of more granular, saturated soils of the Terrace Formation and the Alluvium. The TBM is launched from a figure-8 configuration Pumping/Screening Shaft located within AlexRenew’s operational Water Resource Recovery Facility. This paper discusses the challenges encountered during the launch of the TBM in short mode within a highly congested site and from narrow deep shafts.

Jun 13, 2023

By P. I. James, M. R. Baker

Este artículo analiza la nueva producción de cobre a partir de "minerales de desecho" de baja ley usando la tecnología de Blue Planet Strategies DEMET™ (Dynamic Electrode Mining Effluent Treatment, por sus siglas en inglés), que tiene como objetivo salvar la brecha de procesamiento entre la solución débil de lixiviación en operaciones de extracción por solventes/electrowinning (SX/EW), removiendo electroquímicamente los metales a partir de corrientes débiles y a la vez generando productos concentrados en metales objetivo en un análogo funcional de extracción por solventes (SX). Se estudió el tratamiento de la débil solución de lixiviación pregnant (PLS por sus siglas en inglés) y se usó para estimar los impactos económicos y de producción para una hipotética lixiviación en pilas de cobre brownfield y una operación aumentada DEMET usando SX/EW para tratar el "mineral de desecho." Se presenta la remoción de cobre a un 86% de eficiencia en las placas por debajo de 0,1 g/L de cobre con un consumo de energía de 0.55 kWh/lb de cobre y una concentración del producto mayor a 10 g Cu/L. El modelamiento arrojó aproximadamente $2/ lb para la producción total de cobre y costos de tratamiento menores o iguales a $1/lb con un inmediato aumento del margen bruto de operación del 12% para el brownfield incrementado. Se indicó también un aumento de la vida de la mina con un margen bruto promedio de 38% en la producción aumentada de "mineral de desecho" con valores de cobre de $3.25/lb.

Jan 1, 2014

By T. P. Weldum, W. Conger

"These studies address the relationship between mill media sizing and its grinding efficiency. Starting with the results from a review of the literature, the issues of initial media sizing for a new ball milling circuit, and then optimal media sizing for an existing milling operation, were studied. The Functional Performance parameters “Mill Grinding Efficiency” and cumulative “Mill Grinding Rates” from both plant and test-scale equipment were used, and provide valuable new insight into this topic. A plant media sizing diagnostic tool is presented, as are newly developed testing equipment and evaluation methods, and recent case studies. REVIEW OF MEDIA SIZING LITERATURE For a plant metallurgist to answer the question “How can I maximize plant profit by manipulating this grinding circuit variable?” she must know what effect the variable has on grinding circuit efficiency. Despite the significant cost of grinding media and its potential effect on production capacity, the ‘best’ media sizing remains ill-defined for any given ball mill circuit in the industry today. The underlying reasons for this will be discussed. But the importance of this issue drove Metcom and its industrial partners to take on the challenge of how to engineer the ball charge for an existing grinding circuit. In the absence of any proven method, the first step was a review of the literature. Sponsored by Cleveland-Cliffs, Inc., a broad review of the literature was undertaken, producing “The Effect of Media Sizing on Ball Milling Efficiency” (McIvor, 1997). Among hundreds of publications that were reviewed that discuss the topics of media sizing or wear, forty-five were studied in detail. These were grouped into: plant experiences; laboratory and pilot plant investigations; media wear studies; population balance modeling studies; and general papers on ball milling which included the topic of media sizing. The reader is encouraged to refer to that review. The findings remain unchanged, although some relevant papers have been written since (e.g. Staples et al, 1997; Banasi et al, 1999; Orford et al, 2006; LaMarsh, 2015). The main findings of the review were as follows."

Jan 1, 2018

By J. K. Horbaczewski

The reclamation of an open dragline pit (Pond A3P-2) at the Gibbons Creek lignite mine in east-central Texas required neutralization of acid mine pit water. At the start of treatment with hydrated lime (Ca(OH)2) on March 28, 2000, the pond had partially filled with 913,000 m3 (740 acre ft) of pH 4.9 water. Another 666,600 m3 (540 acre ft) of pH 3.3 water was pumped in from an adjacent pit (PitA3P- 1). By the end of the project (July 5, 2000), a combined volume of 1,579,000m3(1,280ac-ft or 417milliongal) in PondA3P-2 had been successfully treated to pH 8.2 with 431 t (475 st) of lime. This was two to three times more neutralizer than laboratory trials and detailed chemical titration had predicted. The main reasons for the difference are thought to be the inadequate representation in a laboratory setting of some of the chemical reactions that occurred in the field, including incomplete mixing of reactants, reactions with clay minerals in the pit walls, the kinetics of biologically-mediated reactions and the kinetics of aluminum oxyhydroxide polymerization (aging).

Jan 1, 2002

By John Barakso

The Sam Goosly or Equity silver deposit is fundamental- ly a discovery based on the analysis and interpretation of reconnaissance geochemical samples. The discovery was made by Kennco in an area of heavy forestation and wide- spread cover by thin glacial debris. No major mines had been discovered in the vicinity of the discovery prior to the geochemical reconnaissance, and the interpretation of the geochemical results therefore was based on data available through geologic mapping and the sample collection process. In the period 1959-1961, PE. Hirst and his crew, in 1962- 1965 P.T. Blackand his crew, and in 1966-1967 C.S. Ney and P.T. Black and their crew collected geochemical samples from the area of what is now the ore body. Several of these samples were compiled and reanalyzed in the winter of 1966- 1967 for various trace elements, including fluorine. A strong, almost 16-sq-km (10-sq-mile) fluorine anomaly was projected along with a very weak heavy metal anomaly. On the basis of this anomaly, a chalcopyrite-bearing quartz monzonite was discovered in 1967. This was a misleading, noneconomic discovery not associated with the Sam Goosly discovery. The interpretation of the geochemical data by Barakso that summer indicated that another source was responsible for the fluorine anomaly. The conclusion was based on the assemblage of trace elements. Therefore C.S. Ney recommended further regional soil sampling to check the original data. The early results of this follow-up sampling found over 33 ppm silver. First float, then ore outcrop was found in the area of the silver anomaly. The attached reprints complete the development of the property after the discovery of the outcrop of ore.

Jan 1, 1990

By J. H. Daniel

Dust-related respiratory disease remains the major health concern in mining, and health agencies are proposing more stringent standards. The U.S. Bureau of Mines (USBM) is investigating techniques to continuously monitor respirable dust in real-time during the coal or ore extraction process. Continuous monitoring will allow mine operators to evaluate hazardous dust concentrations and adjust the operations to produce less dust. Mine instrumentation applications include machine-mounted and hand-held monitors, personal monitors, and area/environmental monitors. Six dust detection methods have been considered to meet application requirements. These are: light-scattering instruments, a smoke-particle detection technique, correlation of pressure drop across the collection filter with amount of dust deposited, the Tapered-Element Oscillating Microbalance (TEOM) instrument, a method that relates the amount of dust collected on a filter with the vibration of the filter, and beta attenuation measurement of dust. Studies to date have identified the TEOM instrument and the technique of correlating the amount of dust collected with the vibration ofthe filter as having the most promise for success. Development of the machine-mounted monitor is the highest research priority. The application options and progress to date in developing continuous monitoring instrumentation are presented.

Jan 1, 1995

By Egons R. Podnieks, Wallace W. Roepke

Mining technology to utilize vital lunar resources will be required for any commitment to permanent lunar basing. Lunar mining must be viewed both as a major supporting element for space resource commercialization and for creation of human settlements on lunar and planetary surfaces to support long-range space exploration. The Apollo missions to the lunar surface and results from fundamental research on analogue lunar rocks by the Bureau of Mines, and others, have provided the initial data for developing lunar mining technology. The multi-disciplinary research projected in this paper outlines the scientific and engineering needs to realize the lunar mining goals.

Jan 1, 1990

By Daniel de la Rosa, Juan Manuel Mayoral, Damián Vital

"This paper presents a numerical study regarding the loads, and the corresponding damage, taken by the primary and secondary lining of a tunnel built in cemented fine-grained stiff soils. This study aims at establishing more rational design criteria that take into account explicity the lining performance. A 3.5 km long tunnel to be built in a densely populated northwest area of Mexico City, was considered as case study. Series of three-dimensional finite difference models, developed with FLAC3D, were used to simulate the tunnel construction, and to compute the ground settlements, internal forces, bending moments, and displacements acting both on the primary and secondary tunnel linings. Interaction diagrams were used to study the lining performance. Several advancement lengths, and tunnel covers were considered to establish their impact on the loads transferred to the tunnel lining. A practice-oriented damage criterion for tunnels was proposed based on the interaction diagram analysis. INTRODUCTION Lining performance during conventional tunnelling, CT, as defined by the International Tunnel Association, ITA (ITA 2009) is strongly affected by the construction procedure. Special attention must be taken in cemented fine-grained materials, such as those found in the northeast portion of Mexico City, due to the potential of fragile failure (i.e. the soil fails suddenly without important deformation) that these soils may exhibit. During CT, it is assumed that the ground strength contributes to the stability of the excavation, as long as the lining is built correctly. It is common practice to consider two structures, which together form the tunnel support: 1) A primary lining, which is a flexible support, which allows excavation walls to deform to mobilize part of its shear strength, and thus contributes to the tunnel self-stability, and 2) A secondary lining. Commonly, the primary lining consists of several layers of shotcrete. In this case the installation method guarantees perfect contact between the lining and the excavation perimeter. The secondary lining, if required, is used to withstand the load conditions in the long term and also has an esthetic function. This paper presents a numerical study aimed at establishing a performance damage criterion for the primary and secondary lining design in cemented fine-grained stiff soils. Due to the lack of data, the strength and deformation parameters were established through empirically-derived relationships. Three-dimensional finite difference models were developed to simulate the tunnel construction, and compute ground settlements, internal forces, bending moments and displacements acting both on the primary and secondary tunnel linings. Interaction diagrams, along with a damage criterion were used to study the lining performance. From the results gathered insight was gained regarding tunnel lining performance during CT."

Jan 1, 2016

By Jacob Petersen, Jon J. Kellar, Samuel Kessinger, Kiran Green

Belle Fourche Shale was processed and characterized for use as a clay-based ceramic. The shale was wet sieved to produce particles that were ± 150 μm. X-ray diffraction (XRD) revealed that the -150 μm material was enriched in clay content compared to the unprocessed materials, whereas the oversize material was enriched in quartz compared to the undersize sample. Particle size analysis was performed on the—150 μm sample, which showed that the median particle size was around 10 μm. Scanning electron microscopic (SEM) analysis further confirmed the small plate size, which appeared to be primarily layered clay particles. Next, the -150 μm particles were rolled into a green body, dried at room temperature, and fired at 998°C. The fired piece was analyzed by XRD and contained 6 wt% hematite, 55% quartz, 19% microcline, and various other minor amounts of minerals. When fired at 1152 ℃, mullite was found with increasing hematite compared to the 998 ℃ firing. A multi-spectral analyzer was used to quantify the color change of the 998 ℃ fired (orange) to the 1152 ℃ fired (red) samples. Micro-computed tomography (Micro-CT) of the unfired body exhibited very few large pores, while the piece fired at 998°C also exhibited few and small pores, the overall porosity of the fired body increased. Microhardness data, obtained from the aforementioned samples, resulted in Vickers Hardness (HV1.0) values of 70.8 HV1.0 (998 ℃) and 485.7 HV1.0 (1152 ℃). Three-point bend testing was performed, giving an average strength of 23 MPa on pieces fired at 998 ℃. The average bending strength of the samples fired at 1152 ℃, was 55 MPa.

Sep 26, 2023

By SAHENDRA SINGH, SANJIT KUMAR PAL, DHARMITA HORO

The North Singhbhum Mobile Belt (NSMB) lies between two crustal-scale shear zones, the South Purulia Shear Zone (SPSZ) at the north, and the Singhbhum Shear Zone (SSZ) at the south. The Babaikundi-Birgaon Axis (BBA) is an east-west trending secondary shear zone in the NSMB lying south of SPSZ, which is known for the occurrence of gold along with other sulfide minerals within the quartz reefs. The present study has been carried out at north of Ichadih village, which lies on the BBA. The present study attempts combined electrical resistivity tomography (ERT) and self-potential methods along a profile of 470-m length in the Ichadih area to map the potential mineralized zones. Initially, ERT sections generated by Wenner, Wenner- Schlumberger, dipole-dipole, and joint inversion of the combined array have been analyzed, and results are validated through the analysis of model resolution. A prominent low resistivity (10–100 Ωm) associated with quartz reef/limonitic quartz reef at a depth of approximately 30–85 m, encircled by a high resistive (more than 10,000 Ωm) formation associated with metasedimentary rock, has been delineated using joint inversion of the combined array. Further, analysis of self-potential (SP) anomaly using particle swarm optimization inversion also confirms the prominent low SP anomaly at a depth of 77.3 m, which is analogous to the low resistivity anomaly identified in the joint inversion of the combined geo-electric array. Subsequent analysis of a complex synthetic geo-electrical model analogous to the present field situation proves the efficacy of the joint inversion of combined arrays. As a whole, joint inversion of multi-array data is established as an efficient technique for better subsurface imaging in case of the complex subsurface structure. In-depth analyses confirm the possibility of sulfide mineral-rich deposit (quartz reef/limonitic quartz reef) which requires further geological drilling and lithogeochemical sample analysis, for possible future exploration.

Oct 26, 2020

By M. D. Ballain, V. C. Storhok, B. Pesic, J. C. Sever

Northwest Alloys, a wholly owned subsidiary of Alcoa, produces magnesium from dolomite by reduction with ferrosilicon and aluminum. This process produces alkaline by-products in quantities that allow their consideration for use as commercial by-products. Two such products are dicalcium silicate slag, Di-Cal, and magnesium oxide condensate, MgO. The alkaline properties of these materials offer acid neutralizing capability comparable to the traditionally used lime, therefore, warranting a study for their use in applications where the neutralization of acidic waters or process solutions is required, such as treatment of mine waters. In this ongoing study, three mine waters (Bunker HillMine, Berkeley Pit, and Blackbird Mine) were selected for treatment with Di-Cal and MgO. Lime was used as the background control. The solid precipitates were subsequently contacted with pure water at four different pH conditions for stability testing of prepared metal precipitates (expanded TCLP). It was found that neutralization with Di-Cal results in precipitates which are of equivalent to superior stability than those from lime treatment.

Jan 1, 1999

By C. I. Basilio

The mechanisms involved in the adsorption of modified thiol-type collectors on sulfide minerals have been investigated in the present work. These collectors belong to the broad classes of thionocarbamates, thioureas, thiophosphates and thiophosphinates. They differ significantly from the traditionally used thiol-type collectors, such as xanthates and dithiophosphates, in terms of structural features that involve either the introduction of an additional oxygen donor or the alteration of electron densities on donor atoms. Electrochemical studies suggest that the adsorption of these classes of collectors is probably the result of a coupled reaction of the EC-type, involving an initial electron transfer step (E), followed immediately by a chemical reaction (C). Thus, the overall adsorption process is controlled by both the E, and pK of the system. The role of structural features in changing the interaction of the donor atoms with sulfide minerals is also discussed.

Jan 1, 1991

By Richard Collins

The projected depletion and the increasing costs of petroleum and natural gas along with the public and governmental resistance to nuclear energy have caused coal to emerge as one of today's answers to both our short term and long term energy needs in power generation. In order to satisfy this need, major increases in coal production are mandatory, thus requiring more and higher capacity coal transfer terminals. The logic for selecting coal as the major fuel for power generation is based on many different reports on the existing and potential energy sources, which include petroleum, natural gas, hydropower, solar, geothermal, and nuclear. The following is a brief synopsis of these reports for each type of energy.

Jan 1, 1978

By Harvey Parker

"The International Tunnelling and Underground Space Association (ITA) is a nonprofit organization that represents all aspects of the tunneling and underground space industry worldwide. Next year, the ITA will be holding its annual World Tunnel Congress (WTC) in San Francisco, CA, April 22-28, 2016. The ITA’s mission is to be the leading international organization advancing the entire industry and promoting the use of tunnels and underground space through knowledge-sharing and application of technology. This article updates a series of articles about the ITA prepared in 2007 by Harvey Parker, former president of the ITA, in anticipation of the next WTC in San Francisco.ITA accomplishes its goals through a range of activities that includes organizing conferences, workshops and meetings, working group and committee studies, training, experiments and other activities. ITA is also involved in the publication of proceedings, reports, and guideline documents as well as facilitating interaction among its membership and with sister organizations and decision makers. ITA currently includes 73 member nations and several hundred affiliate members, including 15 prime sponsors and 63 supporters. ITA’s membership is comprised of member nations as well as sponsors and affiliate members.The United States has had a prominent role in ITA since its 1974 inception, when it was formed as a result of a worldwide survey conducted in the early 1970s by the Organization for Economic Cooperation and Development (OECD). Bill Lucke, from the U.S., who was in charge of tunnels for the U.S. Federal Railroad Administration, was a member of the organizing committee that created ITA and became a vice president of ITA. Jack Lemley served as president of ITA from 1983 to 1986. Dick Robbins was active in ITA and served for many years as a member of the ITA’s Executive Council and as first vice president. Harvey Parker served as president of ITA from 2004 to 2007. Amanda"

Jan 1, 2015

A bearing isolator is a noncontact, nonwearing, permanent bearing protection device. It has a rotor and a stator, and the two are unitized, so that they do not separate from one another while in use. The rotor turns with a rotating shaft, while the stator is pressed into a bearing housing. The two components interact to keep contamination out of the bearing enclosure and the lubricant in. Bearing isolators do not require lubrication or any particular shaft finish or condition. The best bearing isolators are made of metal, usually bronze. They use a vapor-blocking feature that inhibits the free transfer of vapor contamination when the rotating equipment is cycled on and off.

Jan 1, 2004