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By W. J. Deutsch, W. J. Martin, R. J. Serne

At the termination of mining, the quality of ground water in the ore-zone aquifer must be returned to a condition predetermined by the permitting agency. To immobilize the redox-sensitive elements (e.g., uranium, arsenic, selenium, molybdenum), it has been suggested that a reducing agent be circulated through the leached ore zone. We have conducted laboratory experiments to test the ability of sodium sulfide as such a reducing agent. Sodium sulfide lowered the redox potential of the effluent such that insoluble minerals containing the redox-sensitive elements should be stable. The uranium concentration of the solution decreased by more than three orders of magnitude. In column experiments, by the time 10 pore volumes of the sulfide solution had flowed through, sulfide minerals were forming. The experimental results indicate that the addition of sodium sulfide should cause chemical reduction of the leached sediments, thereby producing long-term stability of the ground-water/sediment system.

Jan 1, 1988

By James Lett

The role of pre-conditioning in a caving operation has multiple benefits, ranging from assisting with improved caveability, normalising fragmentation and improving draw point hang-up frequency. At Newcrest Mining’s Cadia Operations, both the Ridgeway Deeps block cave the Cadia East Panel Cave have utilised pre-conditioning using hydraulic fracturing. Seismic response data inside and outside the pre-conditioned volume show the benefit of treating the full caving block. Cadia East has further developed pre-conditioning to mitigate developing seismic hazards associated with major structures (fault-slip events) and managing mine-wide seismic hazards in new caving operations where the potential for large damaging seismic events exists due to high stresses and hard competent rockmasses. A case study reviewing the impact of pre-conditioning to mitigate seismic hazard associated with fault slip is presented. Cadia East operation undertook a targeted hydraulic fracturing program and reduced the overall number of large events as an example of the benefits of pre-conditioning. This paper will review the application of Hydraulic Fracturing at Cadia and discuss the geotechnical and seismological parameters of seismic events that occur within and outside of pre-conditioned rockmass volumes to demonstrate the benefits that Hydraulic Fracturing bring to future caving operations.

Apr 26, 2022

By Jameel Menashi

Aqueous solutions of Na2Cr04 can be reduced with CO to produce hydrous Cr203 and NaHCO3/Na2CO3. CH3OH, HCOO and HCHO in the presence of CO2 also reduce Cr 6+ and yield similar products. It is shown that the rate of Cr6+ reduction can be represented by the expression -d[Cr6+]/dt=k[Cr6+)1/2[R] where [R] is the aqueous phase concentration of CH3OH, HCOO- or CO. With these three reductants, the activation energies for the reduction processes are comparable and are of the order of 100 kJ/mole. Rapid reduction rates are attained at temperatures in excess of 220°C and, with these three reductants, a green acid-insoluble readily filterable hydrous Cr203 is formed. With HCHO significant reduction of Cr6+ occurs at about 80-100°C and an acid-soluble violet modification of hydrous Cr2O3 is formed. The reduction process is reasonably selective: solutions of Na2CrO4 contaminated with Mo6+ and W6+ can be reduced to yield a Cr2O3 product with significantly reduced contaminant levels. These findings are utilized as a basis for a process for recovering chromium from secondary source materials.

Jan 1, 1984

By Guowen Dong, Qiyong Li, Qiang Li, Tiejun Chen, Zhihong Wu, Junying Wan

In order to search for a more economical and effective roasting additive for extracting vanadium from stone coal and solve the question of the disposal of PVC waste, PVC waste was proposed as a novel roasting additive to enhance extraction of vanadium from stone coal and realize the comprehensive utilization of resources. By adding this roasting additive, the leaching rate of vanadium reached 94.5% under the conditions that the PVC waste addition was 10 wt%, the roasting temperature was 800 °C, the roasting time was 1 h, the sulfuric acid concentration was 15 vol%, the liquid-to-solid ratio was 1.5 cm3 /g, the leaching temperature was 95 °C, and leaching time was 4 h, which increased by 8.4% compared with that of blank roasting. The thermodynamics calculation showed that the decomposition reaction of mica was performed easier with the participation of HCl produced by pyrolysis of PVC. Meanwhile, The SEM-EDS and aperture test analyses demonstrated that more cracks and voids appeared in the roasted sample by roasting with PVC waste, which could facilitate the release and extraction of vanadium. Additionally, the TG-DSC analyses indicated that PVC could provide large amounts of heat for the roasting process to promote the decarbonization and roasting efficiency of stone coal because of its high calorific value.

By Laura Suarez, Jörgen Kajberg, Pär Jonsén

How does an investigation into the breakage characterization of electric arc furnace (EAF) manganese slags contribute to a more responsible usage of resources throughout the life cycle of steel products and reduction of carbon emissions? The main goal of this study is to increase the knowledge on the mechanical response of manganese slag to open the potential of pyrometallurgical residues to become secondary material in industrial applications such as infrastructure construction, fillers, binders and soil stabilization, among others.

Mar 1, 2024

By J. Bigu

A theoretical radiation mine model, suitable for underground uranium nines, has been investigated. In this model, the rate of ventilation and/or the radon (thoron) gas emanation from mine walls are time-dependent. Several cases of practical interest have been investigated including sinusoidal, linear, exponential, stepwise, or a combination of two or more of the above. Analytical solutions were obtained for the time-dependent radon (thoron) gas emanation rate. However, because of the extreme analytical complexity of the solutions corresponding to the time-dependent ventilation rate case, numerical solutions were found using a special Runge-Kutta procedure and the Hamming's modified predictor-corrector method for the solution of linear initial-value problems. The mine model makes provisions for losses of radioactivity, other than by ventilation and radioactive decay, by, say, plate-out on mine walls, and by other mechanisms. Radioactivity data, i.e., radon, thoron, and their progeny. obtained with the above mine model for a number of ventilation and emanation conditions, are presented. Experimental data obtained in an inactive stope of an underground uranium mine for a time-dependent air flow case are shown. Air flow conditions (ventilation rate) were determined by tracer gas techniques using SF6.

Jan 1, 1987

By R. Kadeg, S. Pavlou

A methodology for developing and utilizing risk-based action levels for soils in site closures is discussed. The methodology is based on standard exposure pathway models which are consistent with current regulatory guidance on conducting risk assessment. A simple approach to evaluating the potential for contamination ground water from the projected criteria based on the Toxicity Characteristic Leachate Procedure (TCLP) is also presented.

Jan 1, 1992

By F. Breu, R. Fraser, R. Lawrie

Diesel-powered underground mining equipment is generally accepted as the most productive, safest, and most efficient equipment used in underground mining operations. Widespread application of this equipment to underground mining is restricted, however, largely because of the difficulty of controlling the diesel engine exhaust emissions. This paper briefly examines control devices currently available for underground application, and also discusses the theory and mechanics of controlling diesel emissions with particulate traps and filters.

Jan 1, 1988

By Sahin Furkan Sahiner, Onur Golbasi

Effective maintenance planning is vital for coal mining operations, where haul truck fleets directly determine production continuity. This study presents a discrete event simulation (DES) model for evaluating maintenance strategies under multiple failure modes and their interdependencies. The model integrates corrective, periodic preventive, and opportunistic maintenance, dynamically updating equipment lifetimes through probabilistic time-betweenfailure and time-to-repair distributions. Applied to a fivetruck coal haulage fleet over a one-year horizon, results show that periodic preventive maintenance delivers the highest availability (76%) under unconstrained conditions, slightly outperforming corrective-only maintenance (75%). Opportunistic and integrated approaches performed worse (68% and 69%), reflecting redundancy from overlapping interventions. These findings suggest that structured preventive programs provide the most reliable outcomes when costs and resources are not limiting. The DES framework serves as a baseline for future models incorporating cost, spare parts logistics, and workforce availability, supporting robust maintenance planning in coal mining operations.

Feb 22, 2026

By J. J. Renton

The iron disulphide minerals, pyrite and to a lesser extent marcasite, are ubiquitous to coal and coal associated rocks and are the source of nearly all the environmental problems associated with the mining, processing and utilization of coal. The iron disulphides as well as the other minerals in coal exhibit systematic spatial pat- terns of distribution on both regional and local scales and show predictable associations, most of which are determined by the geochemical-sedimentological controls under which they form. It is the purpose of this paper to discuss the geochemical-sedimentological conditions responsible for the formation of coal minerals with special emphasis on the formation of iron disulphides, to illustrate the regional and local patterns of mineral occurrence within coal, to present the microscopic associations of the iron disulphides and finally, to discuss the most important single environmental aspect of the iron disulphide content of coal and coal associated rocks; the production of acid mine drainage.

Jan 1, 1986

By E. L. McHugh

Digital camera and computer technologies can be used to monitor mine slopes and provide real-time warning of rock falls. NIOSH researchers assembled a surveillance system using low-cost video cameras and computer software from the security industry to test its effectiveness. The system is designed to signal an alarm when motion is detected and to record images of the scene. Masking can restrict motion detection to specific areas within the camera view; sensitivity is adjustable. The time-stamped images provide a record that can help reconstruct and quantify an event. Video motion detection can augment standard monitoring methods to increase safety in surface mines.

Jan 1, 2004

By C. Garcia, H. Arias, J. D. Miller, C. L. Lin

The question of ultimate recovery in heap leaching operations is always of particular concern with respect to economic considerations. Of course the particle size distribution is a critical factor which determines ultimate recovery and which must be established based on a balance between the extent of mineral exposure and transport phenomena. Now it seems that the ultimate recovery for a given particle size distribution can be established from mineral exposure analysis by x-ray microtomography (XMT). Using recently developed software, micro-CT data can be used to determine the fraction of mineral exposed and thus the ultimate recovery. Examples of mineral exposure analysis are given for the copper heap leaching operation at Zaldivar, Chile.

Jan 1, 2002

By Michael J. Virnig, Kathryn C. Sole, Murdoch W. MacKenzie, Michael R. Davis

A solvent-extraction process has been developed for the removal of copper cyanide complexes from aqueous copper/gold cyanide solutions formed in gold-recovery circuits that treat ores containing cyanide-soluble copper. The process uses LIX® 7820, one of the LIX® 7800 reagent series developed by Henkel. It is based on a mixture of Aliquat® 336, a quaternary amine, modified with an alkylphenol, 4--nonylphenol. Extraction and stripping data for the base metal cyanides and thiocyanate are presented. Methods for the recove1y of copper and cyanide from the upgraded strip liquor are reviewed. A flowsheet based on this chemistry and a preliminary economic evaluation of a solvent-extraction circuit combined with the cyanide-recovery process developed by Metallgesellschaft Natural Resources (MNR) are also presented.

Jan 1, 1999

Rest potential, cyclic voltammetry and chronoamperometry measurements were made to study the effects of cathodic polarization of chalcopyrite simulating the mineral contacted with grinding media under a nitrogen atmosphere. The reaction products on the chalcopyrite surface were identified by XPS and the mechanism of the cathodic reaction was proposed. Micro-flotation tests were performed to investigate the effects of surface changes on the floatability of chalcopyrite.

Jan 1, 1991

By X. Tang, N. Ripepi

The Langmuir model has been widely used for the coal-methane sorption process through an isothermal test. However, even though the temperature-dependent Langmuir model was recognized theoretically and experimentally, the quantitative relationships between the Langmuir constants a and b and temperature have not been clarified and confirmed by laboratory test data. This paper collects 158 methane-coal sorption data under different temperatures that apply the Langmuir model to the relationships between the Langmuir constants a and b and temperature. Even though the Langmuir model cannot be used to show the physical state of methane adsorption on coal, it is widely used because of its simplicity and the reasonable explanation of its parameters a and b. The results from these published isothermal tests indicate that (1) there is no consistent relationship between Langmuir constant a and temperature, (2) the Langmuir model is a temperature-dependent model whose temperature-dependent feature is mainly shown by the relationship between the Langmuir constant b and temperature, and (3) the relationship between the Langmuir constant b and temperature can be described by both exponential and linear relationships with dried coal. This paper provides a database for the temperature-dependent Langmuir model that can be used for the reservoir simulation of coalbed methane reservoirs and for the coal seam degasification modeling of underground coal mines, considering the heating effects induced by geothermal and heat injection through factors such as hot water, hot steam and ultrasonics.

Jan 1, 2016

By N. Parra, M. N. Herrera, T. Vargas, B. Escobar, C. Gonzalez

originally published May 1998, Vol. 15, No. 2, pp. 15-1 9 Discussion by G. Rossi, University of Cagliari Reply by T. Vargas, University of Chili

Jan 1, 2000

By E. R. Reeves

The mining industry has recognized the importance of engineering controls as a primary means of preventing hearing loss. The noise control treatments most commonly observed on drills and bolters during this study were windshields, sound absorbing material, and hydraulic motor covers. These controls were evaluated on machines at underground metal mines to determine the amount of noise reduction achieved by each control. The results indicate that absorbing material has very little effect on the noise level. The noise reduction attributable to the motor covers was dependent on the material used to create the cover. Properly installed windshields were the most consistent control.

Jan 1, 2004

By S. Chander

A comparison of gold, platinum and sulfide ion selective electrodes was made for determination of Eh in solutions containing hydrosulfide ions as a model system. The comparison was made in terms of the accuracy of the measured response, response time, pH dependence, and reproducibility of measurement. The sensitivity of each electrode towards changes in hydrosulfide ion concentration was measured in terms of the change in measured Eh per decade change in concentration. On the basis of a detailed investigation of the electrode processes occurring at the surface of gold and platinum electrodes, it was postulated that within the pH range investigated these electrodes respond to changes in the hydrosulfide ion concentration in solution. In comparison, the sulfide ion selective electrode is known to respond to changes in the sulfide ion activity in solution. Although the potentials measured with gold and platinum electrodes were mixed potentials, pretreatment procedures can be used to obtain a signal suitable for process control. For control of hydrosulfide ions in flotation pulps, the use of a gold electrode pretreated at 1.0 V with respect to a standard hydrogen electrode is recommended.

Jan 1, 1992

By J. Kretschmann, T. Rudolph, L. Michael, P. Goerke-Mallet

The mining value chain plays an important role in our societal development. Even in a circular economy, mining and raw materials are in great demand, and so are skilled engineers. In Germany, many students decide to pursue STEM studies in the tertiary degree. Nevertheless, the OECD reports low completion rates in obtaining the degree of studies [1]. Generally, the dropout rates in STEM education are high [2]. Many students have difficulties with basic subjects such as science and mathematics, in which they lack knowledge they should have acquired in school [2]. With the German STE(A)M project PepperMINT (https://peppermint.thga.de/), the Technische Hochschule Georg Agricola (THGA) offers a digital and open educational platform, as a dynamic, massive open, online course (MOOC) for students and prospective engineers. The project is funded by the RAG-Stiftung (RAG-Foundation; No. 20-0004). Using adaptable MOOC classes and applied examples from the wide-ranging cycle of mining activities, we motivate students to engage in STEM studies. Our adaptive and application-oriented content demonstrates the diversity of jobs and career paths in the mining industry. The integrations of applied examples and research activities of the Technische Hochschule Georg Agricola can increase the curiosity and motivation of learners. In mathematics, mine-surveiying technologies and geomonitoring methods (see figure 1) can be used to teach trigonometry. Additionally the concept of the free open online classes enables students in high school to get insights into the field of engineering before they decide the subject of their studies. For freshmen who already decided to pursue a STEM degree, the PepperMINT courses can help to identify and close knowledge gaps and to align different levels of knowledge within a heterogeneous student body. Empowering students in STEM education and integrating examples from mining research can help us train the mining engineers of the future.

Mar 2, 2022

By Kot F. v. Unrug

In spite of extensive research and accumulated experience from mining operations, appropriate coal strength values for pillar design remain debatable. Coal strengths determined in the laboratory on standardized samples vary widely among various coal seams with poor repeatability. Penetrometric in situ strength testing obtains multiple measurements at multiple horizons within the coal seam to provide a strength profile. Alliance Coal has used that method in many of its mines for pillar design. Pillars in these mines perform well. This paper presents a series of case studies and discussion of issues related to coal pillar design. The analysis demonstrates that the proposed default in situ strength of 900 psi is appropriate when no other data exist. However, in the case of appropriate strength measurements combined with analysis of pillar structural composition, differing values can be used successfully. In areas where the penetrometric derived in situ strength is greater than the standard 900 psi in situ strength, reserve recovery has been optimized as required by law without compromising safety.

Jan 1, 2009