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By Panshi Xie, Yingyi Zhang, JIANJIE DUAN, Shenghu Luo

A multi-layer gangue roof of a steeply dipping coal seam with a large mining height face area was analyzed using physical simulation, numerical simulation, theoretical analysis, and field measurement methods to evaluate the roof deformation and the mechanisms associated with the instability of the hard gangue and soft coal interlayer. The results indicated that the first weighting step of the multi-gangue roof was larger than that of a non-gangue roof, but periodic weighting steps were similar. The overburden collapse height was lower in the multi-gangue roof than in the non-gangue roof due to the buffering and supporting function of the collapsed gangue. Moreover, the failure of the coal interlayer was the key factor in the collapse of the multi-layer gangue. A mechanical model was established for the hard gangue and soft coal interlayer based on a revised Prandtl squeezing theory. The limited load of the interlayer and maximum resistance of the shield support was thusmodeled. The maximum resistance of the support increased with the dip angle of the seam and burial depth. It also increased with the interlayer thickness at thicknesses below 2.75 m. It reached a peak when the interlayer thickness was between 2.75 and 3 m and exhibited a decreasing trend when the thickness was greater than 3 m. The results were confirmed using physical simulation and a field test. Certain measures were proposed to control the stability of the gangue roof, including zoning control of the mining height and resistance and advancing the support while maintaining roof contact, thus ensuring the integrity of the support and surrounding rock system.

Jun 30, 2020

By F. H. Seymour

Central to Newmont Gold's Mine planning system is the ability to interactively perform cut and fill operations on topographic contours and to accurately evaluate grades and tonnages within contour outlines using polygon set manipulation routines. This paper develops the applied geometry concepts that underlie these routines. Included are representation of volumes with contours, point in polygon test, block proportion in polygon calculation, polygon area and centroid calculation, and intersection, union, and complement between polygon sets.

Jan 1, 1990

By Marcos Vieira, Gil Vilela, Wanderson Silvério, Livia Faustino, Pierre Fernandes

New global industry standards and regulatory changes regarding mining tailings management are driving installation of tailings filtration plants to decommission existing tailings dams and implement dry stacking. Target of this project was to reduce ultrafine slime tailings deposition. Previous investigation at Samarco concentrator has showed a 35% decrease in tailings filtration throughput when feeding a mix of 95% flotation tailings with 5% slime tailings (compared with 100% flotation tailings), also worsening geotechnical aspects such as material workability during dry staking. Industrial trials using a proper filter aid at tailings filtration plant feeding a mix of 94% flotation tailing and 6% slime tailing (equivalent to 30% of total slime generation) have provided filtration performance maintenance (throughput and cake moisture), and dry stacking the dewatered material. Results achieved will enable life expansion of existing slime disposal structures, as well as potential life of mining extension. Furthermore, reagent chemistry influence is discussed by the light of geotechnical aspects, which has been showing improved KPIs, such as workability, compressibility and permeability.

Feb 1, 2025

By Jan Reimann

Increasing individualization with smaller quantities, growing competition from low-wage countries, and the continuous drive towards digitalization are the challenges that industrial companies in high-wage countries must face. The example of the Flender One gearbox modular system demonstrates how consistent standardization and digitalization are the enablers for AI, and thus already enable new business models and business approaches today.

Feb 22, 2026

By J. R. Evans

Mining claims must have a discovery of a valuable mineral deposit to be valid. When required, a Federal government mineral examiner makes a determination of validity and recommendations thereof to authorized management officials. The examiner should show whether or not an existing mining operation, or a proposed operation have economic viability. This is accomplished through an analysis of legal entities, land status and use, geologic and mineralogic relationships, and mining, milling and processing techniques considered in an appropriate economic evaluation framework. A framework involves market and market entry studies, reserve analyses, all costs analysis, royalty buyouts, tax structure, discount rate of return, and escalation and risk factors. An income approach to value is then used by means of a simple or complex discounted cash flow (DCF) analysis to certify validity. Whether one claim is owned by a single miner, or hundreds of claims are owned by a large corporation, thorough, fair, consistent, and appropriate economic concepts should be applied by the mineral examiner.

Jan 1, 1993

By W. W. Dudley

The U.S. Geological Survey, in support of underground testing of nuclear explosives, has developed a technique (Dudley, 1910) to predict the inflow of ground water to large underground chambers that are cylindrical in shape. By treating the chamber as a large-diameter well pumped at constant drawdown, the nonsteady discharge can be computed by the method of Hantush (1961) for analyzing flowing wells under leaky artesian conditions. In mining applications, whether for mineral recovery or for nuclear testing, the most serious departure from the conditions of Hantush's model results from the gradual enlargement of the opening under drained conditions. Inherent in the analytical technique is that the "well" is fully completed at the time that dewatering begins. Because safety is the prime concern, however, initial pumping systems or personnel evacuation procedures must be designed to handle the greatest conceivable inflow. DEFINITIONS Because somewhat different meanings are attached to similar words in different technical fields, the U.S. Geological Survey definitions (Lohman, 1970) of several hydrologic terms used in this report are given below. An aquifer is a formation, group of formations, or part of a formation that contains sufficient saturated permeable material to yield significant quantities of water to wells, and springs. A confining bed is a body of material lying stratigraphically adjacent to one or more aquifers and having a hydraulic conductivity distinctly lower than that of the aquifer. The total head (dimensions L) of a liquid at a given point is the sum of three components: (1) elevation head, he, which is equal to the elevation of the point above a datum; (2) pressure head, hp, which is the height of a column of static water that can be supported by the static pressure at the point; and (3) velocity head, hv, which is the height the kinetic energy of the liquid is

Jan 1, 1971

By Harvey P. Knudsen

This paper illustrates the application of geostatistics to a roll front type uranium deposit located in Wyoming. The steps involved in calculation of experimental variograms, variogram modeling and verification of the resulting models are described in detail. The resulting spherical variogram models for grade thickness and thickness show strong geometrical anisotropies. The major axis of anisotropy for both variables is approximately parallel to the axis of the roll front and the minor axis perpendicular to the roll. This model confirms the technique of drilling "fences" across the roll front, where the drilling is much closer together than the fences along the roll.

Jan 1, 1978

By Akram Marseet, Andrew J. Petruska, Rik Banerjee

Underground mine roof bolting is a crucial operation for miners’ safety and mine sustainability. Since roof bolting is a manual or human-supervised operation, miners’ safety is at risk due to dust or rock falls. Traditional machine learning algorithms have shown limitations to detecting drillable areas, mainly due to harsh lighting conditions. The authors propose an adaptive deep-learning framework for autonomous roof bolting. The proposed framework is based on implementing a binary semantic segmentation algorithm on color images to classify pixels that belong to rock from those that belong to non-rock. Significantly, the proposed framework implements deep learning semantic segmentation on images from traditional and neuromorphic vision sensors in underground mines. The performance of the proposed model shows an impressive accuracy level of at least 98% at a low number of training epochs with smooth learning curves. The high accuracy enables the implementation of autonomous roof bolting, greatly improving miners’ safety and operational efficiency while reducing human exposure to safety hazards. This research will advance the use of deep learning in mining automation and has the potential to revolutionize the traditional mining industry.

Feb 1, 2024

By Jeremy Cawley, Horry Parker Jr., Clint Wilson

The 5180 m EPBM drive on the Lower Olentangy Tunnel (LOT) is predominantly within glacial overburden. To connect LOT with the existing OARS deep tunnel in limestone bedrock, the upper 15 m inside diameter Vine Street retrieval shaft telescopes down to 6.7 m in diameter and extends into the karstic Columbus Limestone to a depth of 51 m, where a 104 m SEM tunnel will connect to OARS shaft 6. Pre-excavation grouting was reuired prior to lower shaft excavation to reduce potentially high groundwater inows. This paper discusses the secant pile installation, grouting program, shaft excavation, and hydrogeologic observations.

Jun 23, 2024

By Y. Pan, V. V. S. Vytla, P. Tukkaraja, R. BHARGAVA, S. Jayaraman Sridharan

Panel caving is an underground bulk mining method that utilizes gravitational force for mining massive, steeply dipping, and deep-seated ore deposits at a lower operating cost. To control dust and gas emissions entering the production level during the extraction of ore from the draw points in a panel cave, relatively negative pressure is created in the cave by installing an exhaust fan in the exhaust drift located on top of the cave. Since caving is a dynamic process, the design of an effective ventilation system is a challenging task, and therefore, estimation of airflow resistance offered by the broken rock inside the cave is critical. The complex and dynamic nature of caving also makes it difficult to predict the airflow resistance by using traditional approaches. This study investigates the effect of changes in the bulk porosity of the broken rock on the cave airflow resistance using computational fluid dynamics (CFD) approach. The results show an inverse relationship between the cave airflow resistance and the bulk cave porosity. The pressure-quantity characteristic curves presented in this paper provide valuable information for sizing and operating an exhaust fan used for a mature panel cave ventilation.

May 17, 2022

By Mike Harrington, Tung Vu

The Regional Connector Transit Project is a 1.9-mile-long underground light rail system that will connect LA Metro’s A (Blue), E (Expo), and L (Gold) Lines in downtown Los Angeles. This $1.75-billion design-build project is scheduled for revenue service in Spring 2023. The project consists of 21-foot diameter twin-bored tunnels, a 300-footlong crossover SEM cavern, three new underground stations (at 1st Street/Central Avenue, 2nd Street/ Broadway Avenue, and 2nd/Hope Streets), and cut-and-cover tunnels along South Flower, Alameda, and 1st Streets. This paper, which is the continuation of our previous paper presented in RETC 2019—LA Metro Regional Connector Transit Project: Successful Halfway-Through Completion, will provide insight regarding the construction of major components, and the system integration and testing work undertaken for this complex transit project.

Jun 13, 2023

By M. Fan, A. Hobert, W. van Dyk

Low flotation recovery and selectivity have been long-standing problems in the treatment of most ultra-fine phosphate ores. This paper investigates the improved flotation of two ultra-fine Brazilian phosphate ores from Itafos’ Arraias project. These ores are predominantly composed of quartz, muscovite, apatite and a Ca-Al phosphate. As a result of fine phosphate dissemination and associated grinding requirements, column flotation was selected for the metallurgical test program to address the inherent limitations of fine particle flotation using conventional flotation cells. Accordingly, both benchtop Denver cell and laboratory column flotation tests were conducted to optimize their respective flotation responses. Improved flotation performance was achieved using column flotation as compared to benchtop mechanical flotation. In column flotation, a P2O5 concentrate grade of 30.5-31.0% was yielded at a flotation recovery of 83.7-85.1% for the 38x0µm generated ultrafines. The benefits of Eriez’ column flotation technology realized from this study include a higher degree of selectivity, increased recovery, and reduced collector dosage as compared to bench-scale mechanical flotation.

Mar 2, 2022

By Armine F. Banfield

The Purpose of the Paper It is fitting that the first paper of a session on the Financial Aspects of Mining should be on the basic data upon which any financial discussion of a mining project must be based. The history of a mining project starts with exploration in an area considered geologically favorable for mineralization and culminates in the discovery of a body of valuable mineral material commonly known as a mineral deposit. Subsequently more detailed exploration establishes the approximate size, shape, tonnage and average grade of the deposit by surface and/or underground drilling, -surface trenching and/or underground workings. Some preliminary metallurgical testing and other studies, as required, are made at this time. Development work is then carried out to provide representative samples for determining flowsheet and metallurgical balances, preparing the deposit for production and establishing more firmly the grade and mining characteristics of the deposit. A feasibility study is then made of the engineering aspects of the project including the estimation of operating coats, the capital required to place the deposit into production, profit and return on investment. A valuation of the deposit

Jan 1, 1972

By SUHAINA ISMAIL, NORLIA BAHARUN, SHAIK ABDUL RAHMAN, WAN NUR SYAFIQAH ANUAR, MOHAMMAD REZAEI ARDANI

Hypochlorite leaching system is a strong oxidizing solution for metal sulfides, which are naturally associated with gold extraction. This study evaluated the hypochlorite leaching of refractory gold ore by using the response surface method–central composite design (RSM-CCD) as a statistical approach in determining the optimum condition of gold extraction from refractory gold ore. The studied parameters for the gold recovery were pH (4 to 6), concentrations of Ca(OCl)2 (0.5 to 1.5 M) and NaCl (2.5 to 3.5 M) in the solution. It was found that the maximum gold extraction of 82.46% (13.85 g/t) was achieved at a pH of 4.0 with NaCl and Ca(OCl)2 concentrations of 2.93 M and 1.08 M, respectively. The statistical analysis also revealed that the amount of gold recovery in chloride solution was significantly depended on pH as the main factor, followed by concentrations of Ca(OCl)2 and NaCl.

Jan 8, 2021

By E. W. Greig

This paper is an account of exploration for bauxite in the Amazon Basin, Brazil, and particularly of the discovery, exploration and development by Alcan of the Trombetas deposit so a general account of the Trombetas Project has already been published in E/MJ (Anon. 1975) to which the reader is referred for details on owner-ship, infrastructure and construction as well as the proposal for mining and treating the bauxite. It is impossible to consider the Trombetas deposits in isolation. A regional account of bauxite in and around the Guyana Shield and the northern portion of the Brazilian Shield is included and it is suggested that these deposits all formed during Tertiary time under similar conditions.

Jan 1, 1977

By A. Bhatanagar, D. Makhija, A. K. Mukherjee, R. K. Rath, P. Dixit

Characterization and beneficiation of dry iron ore processing plant reject fines of Khondbond region, India, was investigated. Different characterization techniques viz. size analysis, size-wise chemical and density analysis, X-ray diffraction analysis, sinkfloat analysis, thermo gravimetric analysis, scanning electron microscopy, and QEMSCAN were carried out. Based on characterization results, two process flow sheets comprising wet screening followed by conventional gravity concentration and two stage classification with different beneficiation routes were used to recover the iron values from reject fines containing 58.73% Fe, 5.54% Al2O3, and 6.6% SiO2. Finally, suggested flow sheet comprising of two stage classification and advance gravity concentration followed by the combination of grinding, classification, and froth flotation produced iron concentrate of 2.36% Al2O3 with 75.8% yield which can be used in sinter/pellet making.

By C. J. Slaughter, S. P. Harteis, L. L. Chasko, D. W. Alexander

The Department of Health and Human Services (HHS), National Institute for Occupational Safety and Health (NIOSH), Office of Mine Safety and Health Research (OMSHR), with the assistance of cooperating underground mining operations and state agencies, has conducted research exploring devices and technologies that could be used to assist miners navigating through smoke and dust resulting from a fire or explosion. Recent events in mines confirm that smoke and dust can enter and contaminate mine escapeways, creating an atmosphere with severely reduced visibility. This reduced visibility results in substantially increased escape times, possible disorientation or confusion, and increased stress levels, and may prevent evacuation altogether. Tools or devices that assist miners in navigating through smoke-filled areas void of lifelines could make the difference in successful escape from the mine. This paper presents the results of OMSHR research to identify and evaluate tools and devices that could provide meaningful information to evacuating miners in areas with limited visibility and without the benefit of a lifeline.

Jan 1, 2011

By Jack R. Miller

This session has been organized to suggest to you that the development of direct reduction is important to the iron ore mining and coal mining industries. The papers presented this morning will include a discussion of the costs of making direct reduced iron (DRI), the iron ore and coal supplies needed to produce DRI, the financing of direct reduction (DR) projects and, probably most important, the impact of the DR development on the iron ore and coal industries. For starters, this opening presentation offers a brief statement about DR practice and DRI, under the title that should surprise no one: "Direct Reduction: What Is It?" There is always the chance? that a brief statement may become long and complicated. But, by mixing some slides borrowed from Hal Lownie with a larger number of photographs accumulated from other sources, I hope to avoid such pitfalls.

Jan 1, 1978

By C. N. Logan

The Southern Company is one of the nation's largest electric utilities and is the parent firm of five operating companies: Alabama Power, Georgia Power, Gulf Power, Mississippi Power and Savannah Electric and Power. Another subsidiary is Southern Company Services (SCS) which provides engineering and technical sup-port to the five operating companies. This technical support includes the procurement and supply of over 40.9 Mt (45 million st) of coal annually for the 22 coal fired plants in the system. Approximately 80 percent of this tonnage is purchased under long term contracts and the remaining 20 percent is purchased on the spot market. The coal is principally supplied from Alabama, Illinois Basin and the eastern Appalachian coal fields. Most of the coal is delivered by unit train and barge but one plant in Alabama receives all its coal by truck and conveyor belt.

Jan 1, 1990

By Edward A. Nowatzki

The purpose of this paper is to present an example of the application of a theoretically derived mathematical model for track-soil interaction to the evaluation of the mobility of large-scale mining equipment used in open pit operations. The model described by Karafiath and Nowatzki (1978) and presented in detail by Karafiath (1978) was used to predict the performance characteristics of four different bucket wheel excavators (BWEs) on rwo types of copper mill tailings at various moisture conditions. The BWEs considered In the analyses are two-and three-tracked continuous excavators. Most have boom-mounted rotating buckets and swinging side- or rear-discharge conveyors. The analyses were performed at the request of Dames and Moore for the Kennecott Corporation's proposed remining of selected tailings deposits at the McGill, Nevada, concentrator. The objectives of the analyses were to determine whether BWEs would have sufficient mobility In the tailings deposit to achieve satisfactory production rates, and TO compare the predicted performance of the various BWEs evaluated. Good qualitative agreement was obtained between the results of the theoretical analyses performed for the McGil1 operation and the actual performance of BWEs in two South African gold mine tailings impoundments.

Jan 1, 1980