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By Glenn E. Hoffman

Relax: the world today is not running short of many mineral commodities, even though prices are spiraling upward. Einstein?s observation still holds true that everything is still relative, as long as one can pass on the incremental costs of production to the consumer. However, a strong consensus exists among many of the companies comprising the minerals processing industry that it is becoming increasingly difficult to find the easy-to-mine, high-quality resources that make juicy profit margins, which shareholders like. For the most part, the resource cherries have all been picked, and established mineral processing companies that are exhausting their reserves, or in the process of looking to add reserves so as to create longevity for their company, have no recourse but to look long and hard at what were once considered the dregs of the earth. Even end users, such as steel companies, are now looking to become ?miners,? to establish captive iron ore resources. Owning a captive resource facilitates a dependable supply of feed materials, which translates into effective cost control and a guarantee for a thriving sustainable business in the future.

Jan 1, 2012

By J. Noll, D. Yantek, J. Organiscak

The Office of Mine Safety and Health Research of the U.S. National Institute for Occupational Safety and Health (NIOSH OMSHR) conducted laboratory testing of a self-tramming, remotely controlled mobile Dry Scrubber (DS) that J.H. Fletcher and Co. developed under a contract with NIOSH OMSHR to reduce the exposure of miners to airborne dust. The scrubber was found to average greater than 95 percent dust removal efficiency with disposable filters, and 88 and 90 percent, respectively, with optional washable filters in their prewash and post-wash test conditions. Although the washable filters can be reused, washing them generated personal and downstream respirable dust concentrations of 1.2 and 8.3 mg/m3, respectively, for a 10-min washing period. The scrubber’s velocity-pressure-regulated variablefrequency- drive fan maintained relatively consistent airflow near the targeted 1.42 and 4.25 m3/s (3,000 and 9,000 ft3/min) airflow rates during most of the laboratory dust testing until reaching its maximum 60-Hz fan motor frequency or horsepower rating at 2,610 Pa (10.5 in. w.g.) of filter differential pressure and 3.97 m3/s (8,420 ft3/min) of scrubber airflow quantity. Laboratory sound level measurements of the scrubber showed that the outlet side of the scrubber was noisier, and the loaded filters increased sound levels compared with clean filters at the same airflow quantities. With loaded filters, the scrubber reached a 90 dB(A) sound level at 2.83 m3/s (6,000 ft3/min) of scrubber airflow, indicating that miners should not be overexposed in relation to MSHA’s permissible exposure level — under Title 30 Code of Federal Regulations Part 62.101— of 90 dB(A) at or below this airflow quantity. The scrubber’s washable filters were not used during field-testing because of their lower respirable dust removal efficiency and the airborne dust generated by filter washing. Field-testing the scrubber with disposable filters at two underground coal mine sections showed that it could clean a portion of the section return air and provide dust reduction of about 50 percent at the face area downstream of the continuous-miner operation.

Jan 1, 2016

By Jordan Scheremeta, Sudhir Tripathi, Mahfooz Alam

Injection leaching can improve leach ore recovery by displacing retained solutions, enhancing ore wetting, and creating new flow paths for efficient solution collection. This paper presents a method to assess the feasibility of injection leaching in finer-grained, potentially contractive ores (from a geotechnical slope stability perspective) using limit-equilibrium (LE) slope stability analysis and static deformation modeling. LE models were carried out by assigning peak undrained strengths to the heap leach ore material, and modeling the excess pore pressure induced during the injection leaching process using spatial function in Slope/W. Static deformation modeling was completed using the software Fast Lagrangian Analysis of Continua (FLAC) to evaluate the potential for deformations due to the excess pore pressures induced during the injection leaching process. A constitutive model was used to represent the geomechanical behavior of the leached ore material, which enables the prediction of deformation and potential stability issues resulting from excess pore-pressure induced during injection leaching process. The two-pronged approach provides a practical method to assess geotechnical impacts and guide data-driven decisions in injection leaching operations.

Feb 22, 2026

By D. B. Spears

The sillimanite group includes the aluminosilicate minerals sillimanite, kyanite and and alusite, all of which have the same chemical composition (Al2SiO5). This discussion also includes the closely related mineral, mullite(about Al6Si3O15), which, although rare in nature, is produced artificially for industrial use. All of the minerals in this group have a low coefficient of thermal expansion and high corrosion resistance. This makes them desirable for refractory applications, especially in the steel and foundry industries. Other uses include electrical insulators, abrasives and household ceramic products. The minerals in the sillimanite group decompose with an irreversible expansion at temperatures between 1,300° C and 1,600° C (2,372° F and 2,912° F). Sillimanite and and alusite have relatively small expansion on decomposition (4 percent to 6 percent) and, therefore, can be used as aggregates in refractory products. Kyanite’s expansion on decomposition is large (18 percent). So it is sometimes used to balance shrinkage of other materials such as clays in refractory mixtures. For applications requiring high-temperature volume stability, mullite is more desirable. As an additive, mullite improves resistance to creep and corrosion, and imparts thermal and electrical insulating properties.

Jan 1, 2005

By Chee Theng

"Mining professionals are a resilient lot. Sure, copper prices are dismal, permitting processes seem interminable and the top mining companies are shedding jobs like a Shetland sheepdog sheds hair. All the more reason to hone technical skills, reconnect with old contacts and get one’s finger on the pulse of the industry.More than 400 did just that in the balmy sunshine and among the saguaro cactus of the Tucson venue of the SME Arizona Conference.Giving the keynote speech was Patrick Merrin, vice president at Hudbay Minerals (see box), while the luncheon speaker was University Distinguished Professor Mary Poulton, director of the Lowell Institute for Mineral Resources at The University of Arizona.“Attendance was great, especially given the copper price,” said Ta Li, vice president of business development at Tetra Tech and 2001 SME President. “The luncheon speaker was one of the better ones in recent years. Her talk contained a lot of fresh ideas, and practical versus theoretical concepts.”Talk about values, not economicsPraise was unanimous for Poulton, who gave a thought-provoking talk on “The New Face of Mining: The Culture Change for Compatible Mining.” Corporate social responsibility has been embraced by the metals mining industry, and it’s being done right, she said. “So why do we have more conflict? Why are there more protests? Why does permitting take longer and longer?” Poulton made a case for an approach based on compatible, rather than sustainable, mining to present a new face of mining that can be compatible with communities, cultures and the environment, and still be profitable. When the mining industry starts to talk about compatibility between what it is doing and what “me,” as the consumer, wants, what “we,” as citizens of a community, want, and what’s good for the “world,” we’re going to see the next culture change happen, she concluded."

Jan 1, 2015

By O. Ofor

Coal fines of less than 0.5 mm particle size, discarded as too fine for gravity separation, were subjected to flotation tests at varying pH and temperatures using modified dosages of kerosene as oil phase and methylisobutylketone (MIBK) as frother. Optimal coal recovery of over 74% was obtained using 200 kg kerosene and 4 kg MIBK per ton of coal fines at a pH of 9.7 and an ambient temperature of 26° C. The coal concentrate obtained under these optimal recovery conditions assayed 9.10% ash, 0.35% sulfur and 0.011% phosphorus, representing reductions in the ash, sulfur and phosphorus contents of approximately 75%, 43% and 8.3%, respectively. Its gross calorific value was 32.9 MJ/kg, its percentage of volatile matter measured 30.6 and the fixed carbon content was 66.3% (d.a.f). Caking tests showed the optimal concentrate has a standard welling number of 1 and is a Gray-King coke type C. These results show that the optimal flotation product could be utilized for such industrial purposes as steam raising or for processing in gasworks, but it would be unsuitable for metallurgical coke production.

Jan 1, 1993

By J. C. Nigro

The potential use of prereduced pellets in the burden of the blast furnace continues to be a topic of interest. Several excellent papers have been written describing the theoretical and experimental rewards. (1) (2) (3) (4) (5) (6) (7) (8) (9) Significant increases in iron output and substantial savings in coke consumption are major advantages over conventional iron oxide pellets. The savings are especially important in areas where good coking coal is at a premium. Lower handling and transportation costs may also be factors favoring prereduction. When considering the overall cost of making and smelting prereduced materials the optimum metallization level becomes significant. An analysis by Agarwal and Pratt of the thermodynamic aspects of blast furnace operation with all prereduced pellets shows that the criteria controlling coke consumption depends upon the degree of reduction and upon the percentage of oxygen (present as FeO) removed by solution loss.(8) The authors state that although the chances of obtaining large fuel savings are greatly improved when metallization is high, reduction to the highest degree, which is costly, may not result in the lowest energy requirement per ton of hot metal; thus, over reduction could possibly result in wasted energy in the blast furnace.

Jan 1, 1968

By Yi Luo, Jian Yang

Subsurface strata movements and deformations associated with longwall mining operations in underground coal mines could cause various disturbances to subsurface mine structures, ground water bodies, and coalbed methane reservoirs. In order to assess those disturbances correctly and to design effective and efficient mitigation measures, it is necessary to develop an accurate prediction model for subsurface strata movements and deformations. Decades of research have demonstrated that variations of stratification and lithology in the overburden have significant influence on the subsurface strata movements and deformations during ground subsidence process. The key strata theory states that the thick and hard key strata serve as the backbone of the overburden and control the movements of the thin and soft weak strata located above them. From an engineering standpoint, the overburden strata are subdivided into several individual groups by the key strata with each group consisting of a key layer at the bottom and weak layers overlying it. A new subsurface subsidence prediction model considering the key strata effects on subsurface strata movements and deformations has been proposed. In this method, elastic modulus, specific weight, tensile strength, and uniaxial compressive strength (UCS) of each layer are used to identify the key layers and to determine the needed subsurface subsidence parameters. The influence function method, proven to be accurate and versatile for surface subsidence prediction, was employed to predict the subsidence on each of the overburden layers from mining horizon progressively upward to ground surface with the assumption that the predicted subsidence on a given layer serves as the subsidence source for the layer immediately above. The enhanced subsurface subsidence prediction model has been demonstrated with an actual case to show its applicability and improvement.

Jan 25, 2021

By A. Dell’Era, E. Ciro, C. Lupi

The indium recovery via electrowinning from sulfate baths has recently gained significant attention as it does not present toxic emissions, hermetically sealed system requirements, human health, and environmental hazards. Following previous works related to the optimization process for AISI 316L and Ni cathode, it was observed significant importance of the metal supports on the input and output parameters of the indium electrowinning process from sulfate solutions. Thus, comparing input and output parameters in both cases seems very interesting. Particularly, regarding the input parameters, the attention has been focused on the electrolyte composition, current density, and temperature, while productivity, morphology, and structure have been considered regarding the output parameters. Considering the productivity as the optimal output, the findings for Ni cathode were better than that for AISI 316L in most of the selected conditions studied. In the case of morphology, indium grains appear rounded and dendritic on the AISI 316L, while those on the Ni cathode show stratified lamellar grains. Anyway, the indium deposit obtained on Ni cathode shows bigger grains independently from the used operative conditions with respect to that on AISI 316L. Regarding the structure, it is clearly tetragonal, but preferential orientation, crystallinity, and deformation of the structure strongly depend on the metal support.

Jun 14, 2023

By Jianbo Hu, Tao Zheng, Zhao Qihua, Rui Su

Rock mass discontinuities play a significant role in evaluating the stability of rock slopes. It is necessary to collect and analyze these discontinuities to fully understand the mechanical and deformational behaviors of rock masses. Based on the digital images of some slope faces, this paper proposes a framework based on machine learning for detecting and extracting discontinuities. First, digital images and photo poses are combined, the original scene is reconstructed, and 3D point cloud data are obtained. All captured point clouds can be mapped with each image by the direct linear transformation algorithm. Next, the detection machine learning algorithm is used to segment rock mass discontinuities on 2D digital images. Finally, based on the mapping relationship, the 2D digital images that were segmented are transformed into 3D point cloud data. The geometric parameters of the corresponding discontinuities can be extracted by the DBSCAN and the Skmeans algorithm and the characterization of specific rules. The proposed framework was evaluated utilizing a quantity of slope digital images in the Yebatan hydropower under construction, located in Sichuan Province, China, as a case study. The results illustrate that most deviations are less than 10° for the dip direction and dip angle, which verifies the reliability of the proposed framework and maintains acceptable measurement accuracy.

Nov 6, 2022

By C. Newman

"Over the past decade, as conventional underground deposits have been depleted, mining operations have been forced to produce at greater depths and in more geologically and geometrically challenging conditions. As such, there has been a global increase in the application of cemented paste backfill (CPB) in tabular deposits utilizing open stope mining method with a delayed backfill placement. Despite the extensive use of CPB, many fundamental factors affecting the design of safe and economical fill structures are still not well understood. A critical issue in the design of backfilled stopes is the determination of stress states within the fill material itself as well as the surrounding rock mass. Analytical equations provide a means of quickly evaluating the effectiveness of a given design. However, in developing these equations large assumptions are implemented to simplify the design problem. It is important that one understands these simplifications as well as their effect on the overall design. This paper investigates common analytical equations utilized in the evaluation of single vertical backfilled stopes and their assumptions through comparisons to numerical modeling results. INTRODUCTION AND BACKGROUND As the mining industry continues to produce at greater depths and in more geometrically and geologically complex conditions, cemented paste backfill (CPB) has gained traction as a means of providing localized ground support in modern stope-and-fill mining operations. The application of CPB in stope-and-fill mining as a ground support material has led to the reduction of mine waste costs, while increasing both mine production and stability. In an attempt to achieve total extraction of the mining reserve, stope-and-fill mining operations often employ a primary-secondary excavation-support sequence (see Figure 1). In this practice, primary stopes are initially excavated and then backfilled in a two-stage pour; plug and final pours. During the first stage (plug), a CPB material with increased cementitious content is placed at the bottom of the stope providing a strong base from which to build a backfill structure as well as protect mine works from material breakthrough. Following placement, the backfill plug is allowed to cure to a given strength as designated by the mine design. Upon achieving the required cure strength, a less cementitious CPB material is used to backfill the remaining stope area. This is referred to as the final pour stage. With all primary stopes excavated and supported using backfill, the extraction of the secondary stopes commences as primary stopes are utilized as artificial pillars. While the application of CPB in a primary-secondary extraction-support mining sequence allows for a substantial increase in reserve recovery, it is imperative the mining personnel and planning engineers have a clear understanding of the material’s behavior and stress interaction with the surrounding rock mass to ensure the most efficient, cost-effective, and safe extraction of underground deposits."

Jan 1, 2018

It had been more than a decade since this many booths were occupied at an SME Annual Meeting, but at the 2010 meeting in Phoenix, AZ 630 booths were sold to 470 vendors from the entire spectrum of the mining and minerals industry. Exhibitors such as Metso, FLSmidth, West-Tech, ABB, NIOSH, Eriez and Resource West took their usual prominent places on the exhibit floor and were joined by newcomers such as tunnel boring machine manufacturer Herrenknecht AG, Frontier Kemper, the International Society of Explosive Engineers and more than 100 other first-time exhibitors. On the floor, one could find everything from a new pair of boots to a new career in the recruitment pavilion where some of the biggest companies in mining (Barrick Gold, Freeport-McMoRan, Newmont Mining, etc..) set up shop. The following is a look at some of the companies and products that were on display at the 2010 meeting. For information about displaying at the 2011 annual meeting in Denver, CO, Feb. 27 to March 2, contact exhibits@smenet.org.

May 1, 2010

By Turker Hudaverdi, Yasar Agan

This study tries to predict blast-induced flyrock using intelligent modelling techniques. Flyrock is a site-specific phenomenon. Design variables and rock properties highly influence flyrock throw distance. Site investigations were conducted in a sandstone quarry. Fundamental operational parameters, blast dimensions, bench face condition, and rock mass structure were monitored. Stepwise regression technique was applied for variable selection. Burden–hole diameter ratio, in situ block size, and powder factor were determined as the most significant parameters. Considering output of stepwise regression, artificial neural network, ANFIS, and Gaussian process regression techniques were applied to predict flyrock throw. A comprehensive validation was performed using twelve different performance indices. Pre-determination of input parameters supported development of successful soft computing applications. Rock block size was found to be an appropriate input variable for flyrock modelling. In addition to classical performance indices, standardized and symmetric accuracy metrics were quite useful in model validation process. The intelligent models predict flyrock range with an error less than 6 m. The mean percentage errors are lower than 10%. ANFIS seems to be the best model for flyrock prediction. The calculated mean absolute error is 5.36 for ANFIS model.

Nov 12, 2023

By Verya Nasri, Behrouz Esmaeilkhanian, Mohammad Motallebi

The Mount Royal Tunnel (MRT) is a 100-year-old railway tunnel located in Montreal, Canada. The tunnel is approximately 5 km long, 8.7 m wide and 5.5 m high, with a constant 0.6% grade. This existing tunnel will be used by the new Montreal light rail transit network, Réseau Express Métropolitain (REM). This requires the tunnel to be inspected, rehabilitated and made compliant to the recent safety standards. This paper presents the details of the structural inspection and rehabilitation of the tunnel along with the repair methods, addition of a center wall as well as the enlargement of the tunnel section.

Jun 13, 2021

By VIVEK KUMAR HIMANSHU, Murari Prasad Roy, Kaushik Dey, Rakesh Kumar Singh, Ashish Kumar Vishwakarma

Sublevel stoping is the most popular and practiced mining method in underground hard rock mines. Proper planning and its execution is the key requirement for stope extraction using this method. The stope extraction has been a challenging task since decades. The major reason is the unavailability of free faces as compared to opencast bench blasting. The geological and geotechnical parameters change gradually even within the stope itself. So, the blast design parameters should be planned according to the scenario of the upcoming ring. The blast design parameters like burden, toe spacing, inclination of blastholes, diameter of blastholes, charge density of explosive, etc., play an immense role in the rock damage. For the proper breakage of rock, the movement of burden is the prime objective. To study this, an explicit dynamic based modeler of M/s Ansys was used. The burden values were varied from 20 to 65 times of blasthole diameter to assess the optimum burden value during the study. The models were simulated for the rock having uniaxial compressive strength as 35 MPa and 102 mm blasthole diameter. Three holes were simulated having depth around 14–14.5 m. Different blast design parameters and respective blast-induced ground vibration have also been measured at the experimental site. The core samples of the rock present at the experimental site have been used for the evaluation of geotechnical parameters. These geotechnical parameters were used in the simulation models. The volume of rock excavated along the free face has been calculated in each model by varying the burden. It has been found that the burden value can varies from 35 to 40 times blasthole diameter (3.6–4.1 m) to achieve a greater volume of rock along the free face for 102 mm blasthole diameter and rock of 35 MPa uniaxial compressive strength.

Dec 22, 2023

By W. H. Stahl

The continuous vacuum filtration is the solid-liquid separation process that is nowadays most frequently used in the beneficiation industry all over the world. After a development time of several decades, the various filter types such as drum filter, disk filter, plate filter and belt filter can be consideres as a sound functional design ensuring a trouble-free operation. Nevertheless, the vacuum filtration does no longer meet the present and future technological requirements. The moisture content of filter cakes is too high. Their thermal secondary drying is too expensive (coal, ores) and may bring about undesirable material changes and the filter cake conditioning with water-binding substances for dumping purposes is too costly.

Jan 1, 1983

Computer programs commonly used to simulate mining operations generally require a fair amount of data. The common data input methods have been by either creating an ASCII data file or answering numerous questions during the data input phase. Both methods of data entry are tedious, time consuming, and inflexible. A screen handling system has been developed to drive FORTRAN-77 application software for the MS-DOS environment. The system utilizes keyboard functions with an aid of extended ANSI codes. It also allows a multi-view input data entries.

Jan 1, 1990

By R. N. Gow

EH-pH diagrams are useful tools in understanding how mineral surfaces react in solution and particularly how aqueous conditions can be changed to enhance mineral leaching processes. However, successful application of these diagrams requires several things be kept in mind to prevent what others have termed ?gross errors? in their calculation and use. The aqueous Cu-S system is used as the basis for explaining the mass-balanced method of calculating EH-pH diagrams with the thermodynamic equilibrium software, STABCAL. This includes a breakdown of the Gibbs? Phase Rule and how it is employed in STABCAL to modify the diagrams. This methodology was then applied to the aqueous Cu-As-S system and resulting diagrams are compared against examples of those generated using the predominant-ion method. The resulting mass-balanced diagram for enargite (Cu3AsS4) is noted to compare well with spectroelectrochemical measurements using Raman spectroscopy and cyclic voltammetry.

Feb 23, 2014

By Jodi Banta

In an effort to reverse the trend of declining enrollments to mining engineering programs that began in 2015, the University of Arizona has implemented a number of interventions over the past five years, including ramping up its pre-college mining education and outreach, and undertaking several enrollment research projects. This article is the second of two installments to discuss the results of our latest study. The first part can be found in the September 2025 issue of Mining Engineering magazine. To better understand mining’s competitive position, the School of Mining Engineering and Mineral Resources conducted a comprehensive study to determine: 1. How prospective college students, parents and educators perceive the industry, related careers and the mining engineering degree. 2. Factors affecting students’ choices of degrees and career plans. 3. The roles parents and educators play and how they influence students.

Nov 1, 2025

By Edward O. Reinbold

The paper presents the results of a study which involved collection and analysis of airborne pollutant concentration data in two producing underground room and pillar metal mines which use diesel powered equipment in the area near the face. The results include the concentrations of CO2, CO, NO, NO2 and respirable particulate matter measured with the latest portable instruments, and the carbon and hydrogen contents of the particulate matter samples determined by combusting them in a Elemental Analyzer. The carbon and hydrogen contents are used to estimate the amount of diesel particulate matter in the mine ambient air. The short term grab sample concentration data, although not suitable for determining compliance with ACGIH Threshold Limit Values (TLVs), are related to the TLVs so that they may be compared conveniently. Lognormal frequency distributions and the arithmetic mean of the concentration measurement data are used to compare different mine situations. Conclusions are drawn as to which pollutants are most important to control under actual mine production conditions.

Jan 1, 1979