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By Hendri Silaen, Charles Leatemia, Monang Napitupulu, John Kamarea, Arwin Edijanto, Riza Hasan, Avesiena Primadiansyah

The Deep Mill Level Zone (DMLZ) is the fourth panel cave mine in the East Ertsberg Skarn System, (EESS) which lies 500 m below the producing Deep Ore Zone (DOZ) mine and up to 1,700 m below the surface. The interaction between the DMLZ and DOZ is occurring as the DMLZ cave grows vertically toward the DOZ footprint. During this process, a rapid change in the global mine system stress is anticipated. This change is forecasted to drive substantial changes in the magnitude and direction of principal stresses in the DMLZ and DOZ mines at PT Freeport Indonesia. These changes will bring the mine system closer to the ultimate capacity of the excavations and can result in significant impacts to mine stability if not managed. Critical to this management, is understanding cave growth and locations, as well as how these changes will impact stress conditions.

Apr 26, 2022

By Alan R. Johnson

Because of the competitive nature of the iron ore pelletizing industry, commodities required for the production of pellets are continually being scrutinized to minimize their usage and offset rapidly escalating costs. In the Tilden pellet plant, the usage of one commodity, bentonite, has been reduced from over twenty-four pounds per long ton of pellets to as low as eight pounds per long ton. The evolution of bentonite usage from plant start-up to the present time is described.

Jan 1, 1984

By Alan D. Randolph

A size-continuous breakage kinetics model is postulated and supported with industrial grinding mill data. It is shown that the kinetics parameters include the effects of possible classification at the mill discharge. The estimated parameters were then used in the kinetics model to simulate the behavior of a grinding mill in open and closed circuit operation. While material transport and kinetics are equally important in open loop operation, heavy recycle in a closed circuit make a detailed material transport model for grinding unnecessary. In effect, the mill can be considered as backmixed. This suggests that more emphasis should be placed on modeling the classifier than the development of detailed material transport models for the grinding mill.

Jan 1, 1975

By B. R. Stewart

The exclusion of coal fly ash from regulation as a hazardous waste has led to increased interest in returning ash to the coalfields for co-disposal. A multi-year column study used coal refuse with high potential acidity (4% total-S), and two alkaline ashes in various bulk-blends. The unamended refuse acidified rapidly, producing acidic (pH 1.7) leachates, high in dissolved metals. Treatments blended with sufficiently high amounts (20 to 33%) of alkaline ash produced alkaline (PH >8.4) leachates with low metal levels, while lower ash blending rates acidified over time to produce metalliferous leachates. Examination of solid materials indicated that pyrite oxidation was occurring to some extent in all treatments. A regression equation (r = 0.95) was developed to estimate time to net acid release for mixtures of these materials. Ash alkalinity and refuse potential acidity must be balanced to insure water quality for co-disposal environments, or the ash materials should be isolated away from acidic drainage waters.

Jan 1, 1997

By Richard E. Barrett

The relationship between coal characteristics and power plant performance has become a matter of increasing interest to utilities. This relationship can affect the value of coals, decisions as to coal washing, setting penalties for delivery of coal that fails to meet specifications, and justifying buying better coals (at higher costs) before public utility commissions. The study described in this paper was directed to identifying how coal characteristics impact on boilers and related coal and gas handling systems. TVA data for the period 1962-1980 was the basis for the study. Models were developed for boiler efficiency, boiler availability, and maintenance costs as a function of such coal characteristics as ash, sulfur, and moisture content and boiler age. Boiler load and maintenance efforts were considered as variables in some of the models, but were found not to be statistically significant. Although the results of this study are strictly applicable to only the TVA system, they can serve as guides or first approximations for other utilities.

Jan 1, 1983

By CASSANDRA L. HOEBBEL, PATRICK L. YORIO, Emily J. Haas

This study revealed significantly less favorable perceptions of the existing organizational safety climate among workers in the underground coal-mining sector compared with those in the industrial-minerals and sand, stone and gravel (SSG) sectors. Consequently, it is important to consider pragmatic ways in which health and safety management systems (HSMS) in coal mines can alter processes to improve these perceptions. Given the interdependencies of safety climate factors and HSMS elements, researchers explored mineworker perceptions of the supportiveness of organizational safety climate factors among mineworkers and identified significant differences in perceptions across sectors. In this paper, we suggest that health and safety professionals in underground coal mining and organizations with fewer resources or less mature HSMSs focus on these factors to bolster support for proactive safety performance. Potential barriers to implementing or improving relevant HSMS elements and ideas to help foster more favorable perceptions of organizational safety climate are also discussed.

By Richard Emberley, Timothy Shaw, José L. Torero, Jurij Karlovsek, Timothy Gibson

"Tunnel closures are highly undesirable and the lengthiest are generally attributed to structural failures (e.g. Mont Blanc). Although historical data shows structural failures are closely linked to fire, design parameters for tunnel safety are not well defined. Current research has focused on defining the fire heat release rate and temperature, but these parameters cannot be easily used to determined structural performance. The energy transferred to the structure, the heat flux, is required but current literature lacks these values. Full scale experiments were undertaken on passenger vehicles resulting in heat fluxes between 20-70kW/m2. Analysis shows a vehicle fire’s duration is closely linked to its mass. Further analysis shows small vehicle fires can be scaled as a function of the tunnel diameter and the characteristic height of the desired vehicle. The present work provides engineers an appropriate design methodology to undertake informed thermal-structural analysis to minimize the risk of tunnel structural failure.INTRODUCTION Quantifying the effects of a tunnel fire depends on many factors such as the type of occupants, their vehicles and spacing, ventilation conditions and the geometric shape of the tunnel (Ingason and Lonnermark 2011). For design engineers investigating the thermal-structural performance of a tunnel, these factors are typically converted into spatial and temporal temperature distributions (Usmani et al. 2001) using various design curves such as those of ISO834-1, Hydrocarbon, Rijkswaterstaat (RWS) or RABT-ZTV (Promat 2013). However, to define a temperature profile through a structural element these curves require a heat transfer model that incorporates an appropriate boundary condition. The appropriate boundary condition is the net heat flux which is the result of a complex energy balance. For use in heat transfer calculations the net heat flux must account for the tunnel geometry as well as thermal properties of a given structural element and all other surfaces and mediums affecting the transfer of heat (Torero 2014)."

Jan 1, 2016

By Ernest Bohnet

Each mining operation is unique in some aspect ownership; ore body location, size, geometry, grade, mineralogy, hydrology, or geotechnical parameters; or constraints such as environmental regulations. However, all mining operations are alike in one aspect; the prime objective of any mining project is to maximize the return on the investment. This is the golden rule, or in the language of mining, the investor?s law of conservation. A mineral resource, by definition, does not become a minable reserve unless the mineral or minerals can be extracted economically (and legally). The three preceding sections have covered the various types of surface mining options. The choice of the most economic method is dictated primarily by the type of de-posit to be mined, the mining rate, and the physical characteristics of the deposit.

Jan 1, 2008

By James M. Peay

This paper discusses the recently completed organizational development research project, which was addressed to the underground mining industry. The three specific purposes of the project were as follows: (a) to determine whether Organizational Development approaches are feasible in the mining industry, (b) to provide a demonstration that Organizational Development methods can successfully contribute to the safety of underground mines, and (c) to compare the efficacy of classical Organizational Development methods, which are highly trainer- intensive, with trainer-nonintensive management development approaches. The term "Organizational Development" (OD) is here broadly defined as a management intervention for the purpose of assisting an organization with the solution of problems, which are seen by the organization as important. More specifically, we can define OD as a planned effort to improve the effectiveness of an organization through (a) team building and problem solving, which concentrates on the issues of immediate concern to the organization, and (b) efforts to improve organizational communication at all levels of the organization.

Jan 1, 1983

By D. Hodouin

The paper reviews approaches to estimate in a real time fashion consistent mass flowrates and assays, using data from the on-stream analyzers and flowmeters of a flotation circuit. Results obtained with one algorithm operating on-line with an industrial flotation circuit are presented.

Jan 1, 1996

By Ali Soofastaei

Mining operations are increasingly data-rich yet decisionconstrained. Fragmented systems, variability in geology and operations, and sustainability obligations create multiobjective trade-offs that classic analytics cannot reconcile at operational tempo. This paper proposes an end-to-end framework that fuses digital transformation practices (governed data platform, semantic layer, feature store, and MLOps) with generative AI (retrieval-augmented generation, tool-use, and agentic workflows) and decision intelligence (simulation/digital twins and multi-objective optimization). We formalize sustainability-aware objectives, define a practical stack and governance controls, and demonstrate how an AI “decision copilot” can surface options, quantify trade-offs, and document rationale. Two figures illustrate a production-grade architecture and a Pareto frontier for cost–emissions trade-offs; two tables operationalize decision-domain mapping and a transformation maturity rubric. The approach is product- and company-agnostic.

Feb 22, 2026

A charge of the Research Council of the Society for Mining, Metallurgy and Exploration, Inc. (SME) is to ?? identify longer term research ideas/needs, that in the perception of the SME Research Council, could represent significant technology breakthroughs ?? (SME, n.d.). In 2008, the Council decided that instead of unilaterally developing a list of top priorities, it would involve the entire membership of SME in identifying the top priorities. Additionally, it decided to keep the list short. This paper describes the process and results from that exercise.

Jan 1, 2010

By K. Taniguchi, Y. Inada

When underground openings are excavated in rock mass for storage of Liquefied Natural Gas, hereinafter referred to as L.N.G., as its temperature is -162o C, steep temperature gradients and thermal stress occur around the openings. That is, the plastic zone and cracks around openings will expand with time. In this paper, the range of cracks which were obtained by the Crack Analysis Method and the range of the plastic zone which was obtained by the No Tension Analysis Method were investigated and compared.

Jan 1, 1986

By Fred A. Breu, Jerome C. Neyer, James F. Peters, John W. Critchfield

This paper describes experiences with methane and hydrogen sulfide gas encountered during design and construction of a sewer tunnel in rock, in Rochester, N.Y. Design explorations are summarized, including geologic setting, measurements of gasses in test borings, laboratory analyses of gas samples, and measurements of gas pressure and flow rates from a sealed borehole. Contract specifications regarding gas are outlined. Results of the Contractor's additional explorations and testing are presented, along with a description of selected equipment and provisions for ventilation and degassification.

Jan 1, 1985

By W. J. Roberds

A formal and explicit yet cost-effective approach is proposed to ensure that decisions made during mine development are optimum (with respect to their ultimate consequences) as well as defensible. This risk management approach is based on probabilistic risk assessment and established decision analysis techniques, and appropriately considers the relationships among various mine development decisions, tradeoffs among consequences, the uncertainty in predicting consequences, and the benefits of flexibility to respond to changed conditions.

Jan 1, 1992

The effects of additives, sodium hydroxide, sodium carbonate, sodium oleate, oleic acid and polyacrylic acid, on stirred media milling of limestone have been investigated. The results are evaluated in terms of specific surface area, specific energy and energy efficiency as a function of additive dosage, polymer molecular weight, solids concentration and relevant operating variables. Use of additives generally results in changes in specific surface area and energy efficiency, while under certain conditions a more than 100% increase in these parameters can occur. Relevant interfacial properties have been measured and milling mechanisms involved are explored particularly in terms of the effect of additives on the flow patterns at higher solids concentration.

Jan 1, 1996

By Raymond A. Bradbury

Martin County Coal Corporation's operations are located on Wolf Creek in Martin County in the eastern part of Kentucky. The mining complex was started in 1971 and has grown to a 2.273 Mt/a steam coal operation. All of the production goes to Duke Power Company's Belews Creek electric generating station in North Carolina. Production comes from four seams that are mined by deep and surface mining methods. Surface mining accounts for 55% of the production and the remainder comes from 2 underground mines. Continuous miners are used exclusively underground. The preparation plant was originally designed to take coal at the rate of 907 Mt/h but that has gradually been increased to 1134 Mt/h. Other cleaning equipment includes Daniels DMS vessels, Model 77 Deister tables, 355.4-mm R. & S. Hydro- cyclones, Krebs 254-m classifying cyclones, Daniels froth cells and in 1980, 3 Krebs 508-mm heavy media cyclones were added to recover some lost and misplaced material. CMI centrifugaldryers and a Hey1 & Patterson size 100 thermal dryer are also part of the coal preparation equipment.

Jan 1, 1981

By Javad Sattarvand, Frimpong Kwaku Asare

The safe evacuation of miners during an emergency in the shortest amount of time is one of the most essential features of a mining operation. Despite advancements in mine evacuation research, the usage of mine vehicles during evacuation has not been considered. The majority of recent studies have been done on miners’ evacuation on foot. Mathematical formulations including Minimum Cost Network Flow (MCNF) models, Dijkstra's algorithm, Floyd-Warshall algorithm, and Ant Colony Optimization models have been used to solve mine evacuation problems. These models, which concentrate on determining the shortest escape routes during the evacuation, have been found to be computationally expensive and may not offer the best solutions in some cases. The goal of this paper is to incorporate light vehicles in the evacuation process using a mixed-integer programming approach. The methodology aims to minimize the total time required to evacuate the mine, ensuring minimal exposure of the miners to the adverse conditions that triggered the evacuation.

Jun 25, 2023

By Jin Zhao, Weijie Wei, Jinwang Zhang, Xiaohang Wan, Shengli Yang

Reasonable mining-retention ratio (ratio of room width to pillar width) is vital to recovery rate and stope stability in underground mining of solid potassium salt deposits. Based on the engineering background of a solid underground potassium salt mine in Khammouan Province, characteristics of the plastic zone of the pillar, and the variation of recovery rate and stope stability under different mining-retention ratio conditions are discussed. The results show that compared with current room width (8 m) and pillar width (10 m), the optimization method of improvement of stope stability. The research results are helpful to recover as much solid potash resources as possible under the premise of ensuring the stability of stope.

Jun 25, 2024

By T. J. Lutz, L. Yan, J. R. Srednicki, J. A. Yonkey, G. T. Homce

"Federal regulations require the installation of refuge alternatives (RAs) in underground coal mines. Of the in-use RAs, over 95% are mobile RAs with the remainder being built-in-place (BIP) RAs. Heat/humidity buildup has been one of the major concerns with mobile RAs. For BIP RAs, however, there is a lack of in-mine heat/humidity test data to determine the extent of heat and humidity buildup. To quantify heat/humidity buildup in BIP RAs, the National Institute for Occupational Safety and Health (NIOSH) performed a series of heat/humidity tests on a 60-person BIP RA with and without a borehole air supply. At various times during the year, tests were performed with cooled, heated, or unconditioned borehole air to examine how various outdoor temperatures may affect the thermal conditions inside a BIP RA. The results show that the air supplied to a BIP RA may require heating and cooling, depending on the outside air temperatures and the temperature of the mine. For example, during tests with an external ambient temperature above 70°F and a humidity that reached 90 %RH, providing 55°F dew point air was able to keep the internal apparent temperature below the mandated 95°F. Results for each test case are presented. INTRODUCTION The Mine Safety and Health Administration (MSHA) has required the installation of refuge alternatives (RAs) in underground coal mines since 2008 [1]. MSHA requires that RAs provide an environment with breathable air for entrapped miners for a 96-hour period. Heat buildup inside an occupied RA is a serious concern. Without a means to dissipate the heat and humidity generated by the occupants and the carbon dioxide scrubbing system, the temperature and humidity inside RAs could lead to severe discomfort or heat stress depending on the mine ambient temperature before and during occupation of the RA. In its 2006 report, the West Virginia Mine Safety Technology Task Force recommended an apparent temperature limit of 95°F for RAs [2]. In 30 CFR 7.504, MSHA specifies a maximum apparent temperature of 95°F inside an occupied RA [3]. The apparent temperature is calculated using both air temperature and relative humidity [4]. To determine if their RAs meet the apparent temperature limit, RA manufacturers have been performing 96-hour-long heat and humidity tests in laboratories. During these tests, a heat input of 117 W (400 BTU/hr) per person is used to represent the metabolic heat of a single miner [2]. The heat generated by the RA’s carbon dioxide system is also accounted for in testing. To account for this heat, 50 W (170 BTU/hr) of heat per miner is used for a lithium hydroxide scrubbing system, or 30 W (100 BTU/hr) of heat per miner is used for a soda lime scrubbing system [5]. In these tests, air velocities around the RA are minimized to represent the worst-case scenario of an interruption in mine ventilation that might occur in a mine disaster."

Jan 1, 2017