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By Michael J. Beus, Jan G. Patricio

INTRODUCTION The U.S. Bureau of Mines, Spokane Mining Research Center, has been conducting and documenting rock mechanics research in the Coeur d’Alene mining district for the past ten years (1, 2, 3, 4, 14, 15). A current project combines the information gathered from rock mechanics instrumentation, geologic structure, and analytic techniques to improve shaft and support design for the deep mines of the district (3). This project required knowledge of the anticipated loads and the physical properties of the rock mass to provide accurate input data for computer design models. Several techniques have been utilized to determine the physical parameters including the USGS (U.S. Geological Survey) solid inclusion probe, the CSIR (Council for Scientific and Industrial Research) biaxial and triaxial strain cells, and the CSM (Colorado School of Mines) dilatometer. This paper describes the determination of the in situ modulus of deformation in three mines over a period of three years and the evaluation of these results as they applied to this project. The need for in-situ rock mass properties such as the modulus of deformation has stimulated research and development of a large number of instrumentation techniques. One area of continuing interest involves various methods of radial borehole dilation. This concept was pursued by Menard (9) with an apparatus known as the pressure meter, which is used frequently in soil mechanics. Other developments in rock mechanics include the CPC (cylindrical pressure cell) by Panek (11) and the dilatometer by Rocha et.al. (13) in Portugal. The CSM dilatometer, which also utilizes this technique, was chosen for this project because it required a small amount of background study, was inexpensive, and could easily be combined with other experiments being planned for the test locations. Although no previous field applications to hard rock (compressive strengths greater than 20,000 psi) has been documented, the instrument was selected since good results have been achieved in granite, oil shale, and several coal measure rocks (11, 12).

Jan 1, 1977

By C. L. Karr

Establishing suitable control of pH, a requirement in a number of mineral and chemical industries, poses a difficult problem because of inherent nonlinearities and frequently changing process dynamics. Researchers at the U.S. Bureau of Mines have developed a technique for effectively controlling such systems. This technique successfully combines the process control capabilities of fuzzy logic and the search capabilities of genetic algorithms. Fuzzy logic offers an effective mechanism for handling nonlinearities, while genetic algorithms can provide fuzzy logic controllers with real-time adaptive capabilities. This Bureau-developed technique is applied to a laboratory acid-base neutralization experiment. Nonlinearities in the laboratory system are associated with the logarithmic pH scale and the changing process dynamics are due to alterations in pH and buffering capacity input solutions. Results indicate fuzzy logic controllers augmented with genetic algorithms offer a powerful alternative to conventional process control techniques in such nonlinear, rapidly changing systems.

Jan 1, 1992

By Onur Golbası, Berk Gokce

Investment decisions in the mining industry are complicated by sector-specific uncertainties. This study presents a multi-submodule system dynamics model to capture the dynamic complexities of decision-making across mineral property development stages. The model includes five interconnected subsystems: valuation, production, growth strategy, demand, and finance. Developed through system decomposition, expert input, and literature, the model is tested on a hypothetical copper mine with 850 ktpa capacity and 1% cu grade. Simulated over five years with quarterly steps, it estimates an enterprise value of $78.9 million and a target growth rate of 11.2%. Results highlight the significant effects of operating costs, capital policies, and inflation on free cash flow, and the critical role of mineral reserves in sustaining growth. This model supports strategic investment analysis across different minerals and development phases, offering mining investors a robust tool for optimizing decisions.

Feb 22, 2026

By C. E. "Sam" Lovewell

In approaching a discussion of production of cement, I hope I won't be like the porter in the bank who was asked if he could give some details on the rediscount rate. He replied, "Boss, when I said hello, I told you all I know." Need for change every so often is illustrated by the story of the little boy four years old who had not spoken a word in those four years. One morning he said, "This damned oat meal is burned'." His Dad was amazed and said, "Son, how come you haven't said a word for four years and now out of a clear, blue sky you say, "The oat meal is burned." Johnny said, "Well, up to now everything has been all right." Not being a mining engineer myself, and my subject not dealing with mining engineering directly, I can only hope that you will agree that the subject has current relevancy by the feet that it can materially improve our environment by putting to good use a potential environmental polluter; namely, fly ash. The profitable utilization of fly ash can reduce cost of use of coal as an energy source. Therefore, it behooves us all to explore to the greatest depth, the pluses and minuses occasioned by its use wherever possible. My particular subject and my particular interest lie in its utilization as a blend in the production of Type IP Portland-Pozzolan Cement meeting requirements of ASTM C-595, Type IP.

Jan 1, 1974

The capability for on-line measurement of the quality characteristics of conveyed coal now enables mine operators to take advantage of the inherent heterogeneity of those streams and split them into wash and no-wash stocks. Relative to processing the entire stream, this reduces the amount of coal that must be washed at the mine and thereby reduces processing costs, recovery losses, and refuse generation levels. In this paper, new approaches for optimal control of the segregation process, using time series models and empirical distributions, are presented and demonstrated using field data.

Jan 1, 1998

By R. Day

Nahcolite is a naturally occurring sodium bicarbonate mineral found principally in the Piceance Creek Basin of northwest Colorado. An 8-m thick nahcolite bed, 610 m below the surface, is the target of this first commercial nahcolite mine. A chamber and pillar mining system is developed by solution mining parallel 8-m tall by 18-m wide by 450-m cavities initiated along horizontally drilled holes. Hot water leaching, cooling crystallization and flash drying is the process. The sodium bicarbonate product is consumed by the baking, animal feed, industrial and acid rain abatement markets. A project overview, emphasizing the combination of horizontal drilling and solution mining technologies, will be presented.

Jan 1, 1994

By M. Govinda Raj, S. Sridhar, M. Aruna

Hand-transmitted vibration (HTV) exposure is associated with various health risks for operators of mobile mining equipment (MME). The case–control research was conducted to determine the musculoskeletal disorder (MSD) risks associated with exposure to HTVs in the exposed (case) and non-exposed (control) groups. HTV readings were measured at the interface between the hand and the steering device using the SV 105B triaxial hand accelerometer connected to the SV106 human vibration analyzer involving 40 MME operators in accordance with ISO 5349:2001 guidelines. A questionnaire survey was also carried out among both the study groups using Cornell Musculoskeletal Discomfort Questionnaire. The European Union's 2002/44/E.C. was used to assess the health risks posed to the MME operators. Twenty-eight out of the 40 MMEs were generating HTVs exceeding the stipulated daily limits of vibration, putting 70% of the operators at increased risk for developing MSDs. The case group was found to have an elevated risk of exposure with odds ratio (OR) 7.56 (95% confidence interval (CI), 1.159, 49.39) and OR 12.80 (95% CI, 2.436, 67.285) times more likely than the control group to suffer discomfort in the left shoulder and left wrist, respectively, indicating increased risk of exposure to HTV. Additionally, cases had elevated risk associated with exposure to tobacco, OR 9.35(95% CI, 1.856, 47.129) compared to those who did not use tobacco. MSDs were more prevalent in the case group compared to the control group. This observation was validated by the field investigations and the responses of MME operators to the questionnaires.

Aug 2, 2022

By Xuchen Fan, Chenyang Zhou, Yuemin Zhao, Liang Dong, Chenlong Duan

A gas–solid fluidized bed using magnetite particles is an effective methodology for coal beneficiation in the field of dry coal cleaning. Broadening the size range of magnetite used in the bed decreases medium preparation cost. In this study, a tapered fluidized bed was used to investigate a magnetite particle size range of −0.5 + 0.074 mm. The results showed that a tapered fluidized bed effectively strengthens mixing of magnetite with a wide size range (−0.5 + 0.074 mm). The results of beneficiation experiments indicated that with increasing tapered angle, separation efficiency increased and then decreased. The highest separation efficiency was obtained at a tapered angle of 10°. The optimal results showed that the ash content of the concentrate decreased from 31.82% to 12.33% with a probable error of 0.11, which indicated that a tapered fluidized bed was efficient to improve fine coal beneficiation performance.

By Helmut Mischo

For more than 100 years, diamond mining has been Namibia?s most important mining sector. Today, it provides the highest foreign currency income for the country?s development. Since the late 1970s, offshore mining of diamonds has gained more importance and now more than 60 percent of Namibia?s generally high-quality stones come from those offshore deposits, with a steady increase expected for the coming years. Diamonds in Namibia The mining industry is one of the three pillars of the Namibian economic development, along with tourism and fishing. Diamond mining is one of the two main mining activities in Namibia and diamond mining operations are rapidly moving from onshore to offshore deposits. This article provides a comprehensive overview of the current and future situation of the Namibian mining industry, with a special focus on the tasks and new technical developments for the successful excavation of beach and marine diamond deposits. The different deposits and the adequate applied mining technologies and methods are shown in examples.

Jan 1, 2011

By Chee Theng

"Mineral processors know you can put in the best technology in the world but it won’t work optimally without the support of the operators. Conversely, you may have complete operator support but won’t get top results without the right technology. When the two come together, the returns can be phenomenal.The first day of talks at the 68th Annual Colorado MPD Conference, held April 26-28 at The Broadmoor in Colorado Springs, covered the ground on these industry wisdoms.Coming together as a team“Think of the people, not just the lab and the numbers. That makes all the difference,” said Dee Kippers, of FMI Henderson Mine, in her talk on “Process optimization during a market downturn (A Moly MacGyver story).” Kippers told an entertaining story of the journey she and her team took in tackling the issue of an annual spike in iron content in the product at Freeport- McMoRan’s Henderson primary molybdenum mine near Empire, CO.As the metallurgists tried one thing after another — cranking up the iron depressant, adjusting pH with sodium hydroxide and hydrated lime, modifying reagent levels — Kippers found that when she shared her results with the operators, communicated with them on what she was doing and got their input, they were more willing to work with her, and more understanding and supportive of her efforts.The results make the case for getting people on board and coming together as a team. The cost savings from their optimization efforts, with little capital investment, have been “enough to cover the annual salaries of our metallurgy department and then some,” Kippers said.Considering the environmentDavid Lemieux, of Dundee Sustainable Technologies (DST), talked next on “Cyanidefree process for gold extraction,” presenting the results obtained from a demonstration campaign of the company’s novel chlorination process for gold extraction and associated arsenic stabilization process. Developed at an investment cost of C$35 million, they are ready for commercialization, having been demonstrated on the laboratory, pilot and demonstration scales.The DST process is differentiated from the Plattner chlorination process, which was in use from 1851 to 1916, by moderate process conditions of atmospheric pressure and ambient temperature — the result of using sodium hypochlorite solution, or bleach, instead of direct injection of chlorine gas — and new, cheaper materials of construction, such as polymers, plastics, fiberreinforced plastics and Teflon, resulting in lower capital and operating expenditures."

Jan 7, 2018

By Vanessa Viterbo, Lia Walker, Hassan Khaniani, Vitor Viterbo

Fatigue is a major contributor to haul-truck incidents in mining, with up to 65% of fatigue-related events associated with operator drowsiness or microsleep episodes, Williamson et al. (2011) and Caterpillar (2007). This study examines whether operator fatigue produces measurable and repeatable signatures in haul-truck telemetry. Eight confirmed fatigue-related disengagement events were analyzed using 20-minute telemetry windows centered around the incident. Statistical descriptors, Z-score normalization, first- and second-order derivatives, sliding-window variability, and cross-signal correlations were extracted from engine speed, throttle position, fuel rate, ground speed, and brake indicators. A logistic regression classifier was trained and evaluated using leave-one-event-out cross-validation. The model achieved a receiver operating characteristic (ROC) area under the curve (AUC) scores of 0.75–0.79, demonstrating consistent discriminative capability. A characteristic shutdown sequence characterized by sudden throttle collapse, fuel-rate decay, RPM reduction, and unbraked coasting was observed across all events, indicating operator disengagement rather than mechanical malfunction. Earlywarning indicators appeared 90–500 seconds before shutdown in the events analyzed, suggesting practical potential for real-time fatigue prediction. These findings provide initial evidence that telemetry-based fatigue detection is feasible and could enhance safety in mining operations.

Feb 22, 2026

By T. M. Klemetti, T. J. Batchler, T. J. Matthews

"From 2011–2016 there were 1,511 documented injures, including 7 fatalities, from ground falls in U.S. underground coal mines. The majority of these ground fall injuries were not caused by a major roof collapse, but from falls of smaller rocks from the immediate roof. Roof screen can significantly reduce the number of these injuries and has been widely utilized in underground coal mines for surface control. Because of the potential of reducing ground-fall injuries, the National Institute for Occupational Safety and Health (NIOSH) is further evaluating the performance characteristics of welded wire screen as used in underground coal mines by conducting a laboratory testing program at the Mine Roof Simulator (MRS) in Pittsburgh, PA. The load-displacement characteristics of a 2.4-m x 3.7-m panel of 8-gauge welded screen were evaluated using a newly designed, large laboratory screen test frame with multiple load pull locations. This screen was tested in a configuration that simulates current installation practices in U.S. coal mines. In this study, the effects of displacement loading rate, load pull surface geometry, and the inclusion of roof channel on the screen performance were evaluated. Ultimately, the type of information obtained in this and similar studies can be used to aid in developing wire roof screen design criteria and to assist mine operators in the selection and use of roof screen in underground mines. INTRODUCTION Over 1,500 injures, including 7 fatalities, occurred from 2011–2016 from ground falls in U.S. underground mines with the majority of these ground-fall injuries caused by falls of smaller rocks from the immediate roof. Various controls are currently being used in mines to control this surface rock, including the use of wire roof screen. In mines where wire roof screen has been installed, injuries from rock falls have been reduced dramatically (Robertson and Hinshaw, 2001). Roof screen has the potential to prevent hundreds of injuries caused by the fall of small rocks between permanent roof supports (Comptonet al., 2007). Because of this potential for reducing ground-fall injuries, the National Institute for Occupational Safety and Health (NIOSH) is evaluating the performance characteristics of welded wire screen as used in underground coal mines by conducting a laboratory testing program at the Pittsburgh Research Laboratory (PRL)."

Jan 1, 2018

By L. E. Eary

Many of the major international gold mining companies provide data on rates of greenhouse gas (GHG) emissions as part of their environmental reporting commitments. These data are evaluated by an index defined as the annual GHG emission rate in metric tons, divided by the annual amount of gold produced in grams, and referred to as GHGgold. This paper examines ranges of GHGgold values for a cross section of gold mines as a function of mining method (openpit, underground and combined operation) and ore-processing method (mill, heap leach and combined methods) for reported ranges of operational data, including annual total tons mined, ore processed and gold grade. The evaluation shows that ranges and distributions of rates of GHG emission are approximately similar across different mining methods and ore-processing methods. The data presented in this paper provide the context needed to make comparisons of GHG emissions reported in companies’ annual reports to the ranges reported for the overall gold mining industry.

Jan 1, 2009

By A. Bruynesteyn

The results of a 2 phase evaluation program designed to determine the amenability of an oxide ore from the Butte, Montana mine of the Anaconda Company to a sulfuric acid leach is presented. In the phase 1 preliminary evaluation, using roll tests and percolation leaching in small columns, it is shown that the ore is highly extractable at low acid consumption ratios. In the phase 2 confirmatory tests in large columns on l-l.5 tons of material, the amenability of the ore to the leaching process is proven and pregnant solution grade profiles from planned commercial heaps established.

Jan 1, 1978

By B. Barry, M. S. Klima

"Testing was conducted to evaluate the effects of hydroacoustic cavitation (HAC) treatment on two bituminous coal slurries and the subsequent separation of each slurry in a classifying hydrocyclone. HAC treatment was performed using a pilot-scale circuit fabricated by Furness-Newburge Inc. The circuit was designed to induce cavitation by means of flow through an ultrasonic resonator chamber or enhanced cavitation by initial flow through a cavitation chamber followed by flow through the ultrasonic chamber. The test materials were nominal -1,500-micron and -150-micron Illinois-basin bituminous coal slurries, which were obtained from an operating coal preparation facility. After 5 sec of HAC treatment, the median size of the -1,500-micron material was reduced, with ash values for certain size fractions decreasing more than 5 percent compared with untreated samples. Extending treatment time led to greater degradation of the +1,180-micron material and an increase in the -25-micron material, with ash reductions occurring for material in the -850+150-micron size range. Size degradation was less for the -150-micron material. Subsequent separation of the treated slurries was carried out in a hydrocyclone with diameter of 102 mm. HAC treatment led to a decrease in the ash value and an increase in the heating value of the underflow stream compared with the feed material. For example, the ash value was reduced by about 16 percent for the -1,500-micron material and 25 percent for the -150-micron material with heating value increases of 7 and 33 percent, respectively, after HAC treatment. Overall, HAC treatment appeared to have a slight effect on the size selectivity curves.IntroductionUltrasound in the range of 20 to 1,000 kHz, referred to as power ultrasound, consists of high energy waves that can create zones of compression and expansion when used to irradiate liquids (Frederick, 1965; Leighton, 1994; Mason and Lorimer, 1988). This action generates varying pressure regions leading to cavitation or the formation, growth and near-immediate collapse of microscopic voids or bubbles (Frederick 1965; Leighton 1994; Mason and Lorimer 1988). Collapse occurs when the bubble reaches critical size and cannot absorb additional sound field energy, and the critical size is governed by the ultrasound frequency (Shchukin et al., 2011)."

Jan 1, 2015

By A. G. Moon

Kennecott Copper Corporation's Chino Mines Division concentrator is located in Hurley, New Mexico. Construction of the concentrator was started in 1910 and its capacity was progressively increased over the years to the present nominal 20, 425 t/d of ore (22, 500 stpd). The principal copper minerals present in the ore are chalcopyrite and chalcocite with much of the chalcotite intimately associated with pyrite. Lime is used to depress pyrite, and flotation at a high pH or alkalinity is required for optimum recovery of chalcocite with good rejection of the pyrite. Regrinding is also required to liberate chalcocite-pyrite middling grains. Accurate control of the lime addition is necessary to obtain both optimum metallurgy and minimum lime usage. At low pH levels, flotation cell control is difficult due to excess froth, but excessively high pH levels can go unnoticed because froth characteristics do not change from those experienced at the deisred pH. With manual control of the lime addition, the desired pH can be exceeded for periods of up to two hours. In 1972 a major renovation of the flotation and regrinding circuits was com¬pleted and at that time a new lime distribution and control system was placed in operation. Limestone is obtained from a nearby quarry west of Hurley. The limestone is crushed, sized and fed to a rotary kiln and the quicklime product is stored prior to slaking. The lime is slaked, as required, in a mixing tank-classifier type slaker and the lime slurry is pumped to a concentrator storage tank from which it is distributed through a conventional closed loop system. The current average lime usage rate is approximately 6 kg/t of ore (12 lb per st).

Jan 1, 1976

By K. A. Lewandowski

Heap leaching efficiency is reduced by poor solution flow characteristics (channeling and ponding), which result from compaction and fines migration. Agglomeration of the ore can prevent compaction and immobilize fines, but copper leaching requires an acid-resistant binder to stabilize the agglomerates. Until now, there has not been a satisfactory way to evaluate whether a binder was effective, other than squeezing a handful to see if it ?feels right.? Procedures have been developed to quantitatively determine whether a binder produces agglomerates that can withstand compaction in an acidic solution, and have identified several binders that will provide sufficiently compaction-resistant agglomerates for copper heap leaching. Keywords: Copper heap leaching, Binder performance, Compaction

Jan 1, 2010

By Adil Jamali, Taufiq Hidayat, Imam Santoso, Zulfiadi Zulhan, Indah Suryani

The study investigates the segregation of iron and titanium in iron sand concentrate pellets reduced using coal under an isothermal-temperature gradient profile. The results show that metallic iron migrates to the surface while titanium and other oxides move to the center of the pellet. The study provides insights into the reduction process and the behavior of iron and titanium during heat treatment.

Mar 2, 2022

By Ronald M. Tipton

Freeze and thaw deterioration is a serious problem In con¬crete pavements. The main cause of distress Is thought to be the pore structure of coarse aggregate. In an attempt to characterize deleterious pores, the Iowa Pore Index test and the Expected Durability Factor, as Calculated from the mer¬cury intrusion porosimeter, were devised. This study Included freeze-thaw and sodium and magnesium sulfate soundness testing of sixteen carbonate aggregate samples. In addition, the Iowa Pore Index and the Expected Durability factor were determined for each of the samples. All of the Above mentioned physicochemical parameters were examined using bivriate correlation analysis with the In¬tent to evaluate the effectiveness of the Iowa Pore Index and Expected Durability factor for predicting the frost dur¬ability of an aggregate. The results from the bivariate correlation analysis showed no significant correlation, between the Iowa Pore In¬dex And- Expected Durability factor with the other physico¬chemical parameters investigated. Rust interesting is that the Iowa Pore index predicted that All of the tested samples would resist freeze-thaw failure, whereas the Expected Durability factor predicted that -ash sample would he non-durable.

Jan 1, 1987

By Eduardo Poltronieri Trés, Anderson Denadai Thomazini, Rodrigo Boyer Fernandes, Francisco de Assis Dutra Macedo, Gilvandro Bueno, Maycon Athayde, Rossano Augusto Pilon Nunes

The fundamental importance of comminution by high-pressure grinding roll (HPGR) technology to efficiently increase the particle surface area lies in lower energy and water consumptions for iron ore pellet feed production. This study compared the ball wet milling process with the innovative HPGR processing technology for hematite-goethite ores. Green-pellet balling and induration processes were simulated on the bench and pilot scales.