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By Malcolm T. Wane

The subject matter of this paper, "Applied Rock Mechanics?," has its genesis in a recent field trip taken by the author. A more or less standard question asked at the mines visited was "How are you using the principles of Rock Mechanics to assist you in maintaining an efficient, safe, and competitive mining operation?" The question was couched in a number of different forms, but the intent was to determine whether or not a general theory based on reason and the scientific method was applied or whether the alternatives of tradition, intuition, ?common sense', revelation, ?shotgun methods' or authoritarianism were invoked. Perhaps two responses to this query will be illustrative of the general nature of the replies. At operation XYZ an extension to the known ore body has been found. The extension is of large enough size and grade that a mining scheme using load-haul-damp techniques is envisaged. Since this represents a departure from the present mining scheme, questions have arisen regarding pillar sizes, room and entry sizes and possible support requirements. A task force has been set up to expeditiously plan for these things and write the necessary specifications and requirements. The fundamental question was posed to members of this group.

Jan 1, 1971

By Shahab Alizadeh, Ahmad Khodadadi Darban, Mehdi Mohseni, Mahmoud Abdollahy

This study probed the selective separation of lanthanum and yttrium in a nitrate medium in the presence of aluminum and calcium impurities using di-(2-ethylhexyl) phosphoric acid (D2EHPA). The factors studied in a central composite design (CCD) included extractant concentration, pH, concentration ratio of total impurities to rare earth elements, and interaction of these three factors. The extraction mechanism and types of extracted metal-containing species were delineated by the slope analysis method. The obtained thermodynamic data showed that lanthanum and yttrium extraction by the D2EHPA extractant was exothermic. The extraction of both rare earth elements was accompanied by an entropy reduction. The negative magnitude of ΔS in yttrium extraction reaction suggests stronger D2EHPA-Y(III) complexation relative to La(III). As entropy decreased and enthalpy increased, the extraction process became unspontaneous. Using the proposed flowsheet, lanthanum and yttrium products with > 90% purity were obtained.

Aug 10, 2021

By D. J. Miller

Environmental considerations are extremely important in planning and carrying out mergers, acquisitions and real estate transfers. It is not inconceivable that potential or actual environmental liabilities could exceed the targeted company's net worth or the book value of the real estate of interest. It is therefore essential that an environmental due diligence investigation (DDI) be performed to quantify environmental liabilities before sales, mergers or acquisitions. This paper will discuss general procedures used in environmental due diligence investigations. The emphasis will be placed on mergers and acquisitions. It should be pointed out that the procedures discussed in this paper are general and must be modified to fit each particular merger or acquisition under consideration.

Jan 1, 1988

By J. M. Pachter

Property sales and acquisition are prominent features of today's coal industry. Before selling or buying a site, a company must know the property's economic net worth. Any evaluation of economic net worth would be inadequate if determinations of a property's environmental liabilities and costs were omitted. Short-term and long-term costs can result from liabilities related to reclamation, water treatment, subsidence, and hazardous waste disposal. A structured, interdisciplinary approach can aid in the delineation, summation, and scheduling of these costs and liabilities.

Jan 1, 1986

By Nilufer Kursunoglu

Despite being crucial for meeting the world’s energy demands, coal mining operations present considerable health risks, especially when it comes to exposure to coal dust. Longwall coal mining, an advanced technique, has considerably enhanced production but made dust control more difficult. Due to its explosive nature, coal dust continues to be a serious and dangerous concern in the industry despite developments in safety technology. This study aims to comprehensively assess the risk of coal dust explosions by integrating fuzzy risk matrix and Pareto analysis methodologies, offering precise risk ratings for various root causes. A fuzzy risk matrix was developed to assign exact risk ratings to identified root causes. Additionally, a Pareto chart was used to identify the main reasons and suggest particular preventive measures. 17 significant causes were determined for underground coal mines based on the study’s methodology, and some preventive measures were suggested. In accordance with fuzzy risk rating values, root causes were divided into six categories. The root hazard with the highest risk rating was identified as ‘accumulation of inflammable gas/gases’. The proposed approach was used to examine incidents caused by coal dust explosions in Turkish coal mines in order to demonstrate the effectiveness of combining the fuzzy risk matrix and Pareto analysis for assessing coal dust explosions. This study gives not only a solid framework for risk assessment but also critical information for classifying the risks associated with coal mine dust explosions. The results highlight the critical necessity for proactive and preventive actions to reduce the hazards of coal dust explosions and protect the safety of mining workers.

Nov 16, 2023

By Milton Gomez, Nico Sutmoller

Low-density cellular concrete (LDCC) was first introduced to the market in the early 1900s and since then has made continuous technological advances. There are two primary types of LDCC: permeable and non-permeable. Both types of cellular concrete offer advantages in different types of geotechnical engineering applications. Because of its unique characteristics of low density, high compressive strength, and high fluidity during placement, LDCC offers an effective solution for a wide variety of engineering applications, and in many cases provides a more cost-effective, labor saving alternative to traditional fill materials. This paper will review the history, characteristics, and technological advances of LDCC, highlighting multiple real-world case studies that showcase the high-performance capabilities of both permeable and non-permeable LDCC.

Dec 1, 2022

By D. K. DeForest

The olfactory system (sense of smell) is crucial to the ability of fish to avoid predators, recognize kin, and synchronize reproduction (Baldwin et al. 2003). Copper (Cu) has been shown to impair olfaction in juvenile freshwater life stages of salmonids (including Pacific salmon and trout) in some laboratory experiments; and in the United States, public concerns have been expressed that current regulatory criteria for Cu in fresh water are not adequately protective of olfactory function in salmonids (e.g., OSU 2007; Pearson 2007). These concerns have largely been raised because some Cu concentrations that have caused olfactory impairment in salmonids in the laboratory are less than Cu concentrations that have been shown to reduce salmonid survival, growth, or reproduction (the effects endpoints that are typically considered in deriving ambient water quality criteria). However, two important and interrelated points that must be considered: (1) freshwater Cu criteria are "driven" by the sensitivities of several invertebrate species that are more sensitive than the olfactory impairment threshold in salmonids when (2) the influence of water chemistry on Cu bioavailability is properly considered in deriving Cu criteria. Bioavailability refers to the ability of various chemical forms of Cu to interact with receptors on the surface(s) of organisms and thus directly cause toxicity or uptake by the organisms. The toxicity of Cu and other metals to aquatic organisms is a function of water chemistry. For example, acute Cu toxicity in fresh water generally decreases as pH, water hardness (Ca2+ and Mg2+), alkalinity, and dissolved organic carbon (DOC) concentrations increase (Meyer et al. 2007). The U.S. Environmental Protection Agency (USEPA) has recommended hardness-based freshwater aquatic life criteria for Cu and other metals since the 1980s (e.g., USEPA 1985); and hardness-based metals criteria decrease (i.e., become more restrictive) as water hardness decreases. More recently, the USEPA has recommended freshwater aquatic life criteria for Cu based on the biotic ligand model (BLM; USEPA 2007), which accounts for the influence of multiple water chemistry parameters, including DOC, pH, alkalinity, Ca2+, Mg2+, and several other cations and anions. The BLM-based Cu criteria generally decrease as DOC concentration, pH, alkalinity, and water hardness decrease. Because DOC has a stronger influence on Cu bioavailability than water hardness, hardness-based and BLM-based Cu criteria can differ considerably. For example, in water that has low DOC and high hardness, the hardness-based Cu criterion would be relatively high (because it is driven by the high hardness) but the BLM-based Cu criterion would be relatively low (because it is driven by the low DOC). Thus, any evaluation of the protectiveness of Cu criteria against a given effect, such as olfactory impairment, must properly account for the chemistry of the exposure water. Meyer et al. (2013) compiled data on Cu-induced olfactory impairment and olfactory-induced behavioral effects from tests in which BLM parameters were measured. They demonstrated that the USEPA's BLM-based freshwater life criteria for Cu are protective against olfactory impairment, because it adequately accounts for water chemistry (whereas the USEPA's hardness-based Cu criteria are not consistently protective). Olfactory impairment by Cu is now receiving increased attention in Canada and Europe (e.g., Wall 2013; Stang 2013). Accordingly, in this paper we have expanded the analysis of Meyer et al. (2013) to consider copper guidelines from various other countries and whether these guidelines are protective against olfactory impairment.

Feb 23, 2014

By Rebecca Boakye, Zohreh Kazemi Motlagh, Virginia T. McLemore

The most significant uranium (U) deposits in New Mexico are sandstone-hosted deposits in the Morrison Formation (Westwater Canyon Member), where >169,500 short tons of U3O8 were produced from 1950 to 2002. In addition, >9076 pounds of vanadium (V, a critical mineral) and some molybdenum (Mo) were produced from these deposits. These and other U deposits (limestone-hosted, U-veins) in New Mexico also contain critical minerals. Critical minerals are mineral resources that are essential to our economy and whose supply may be disrupted; many critical minerals are 100% imported into the U.S. Some sandstonehosted, limestone-hosted, and U-vein deposits are elevated in heavy rare earth elements. One sandstone-hosted sample contained 0.3 ppm Re (critical mineral), 659 ppm Se and 408 ppm Mo. The arsenide five-element vein deposits in the Black Hawk district are mineralogically and texturally complex, low- to moderate-temperature, hydrothermal, structurally-controlled, Ag-Co-Ni-Bi-As bearing carbonate vein systems with local minor elements. Mineralized samples from Black Hawk contain up to 9970 ppm Ag, 8540 ppm As, 5690 ppm Co, 72,400 ppm Ni, 57 ppm Bi, 165 ppm Sb, and 32,600 ppm U.

Feb 22, 2026

By Steve Kral

The Prospectors and Developers Association of Canada (PDAC) was established in 1932 in response to proposed regulations that would have threatened prospectors in Ontario. From there, the association grew to represent the interests of Canada?s mineral exploration and development industry. The PDAC?s mission statement reads: ?The PDAC exists to protect and promote the interests of the Canadian mineral exploration sector and to ensure a robust mining industry in Canada. The PDAC will encourage the highest standards of technical, environment, safety and social practices in Canada and internationally. ?Today, the PDAC?s 6,000 individual members include prospectors, developers, geoscientists, consultants, mining executives and students. In addition, the association?s membership includes 950 corporate members, representing senior, mid-sized and junior mining companies in addition to organizations that provide services and equipment to the mining industry. In 2010, the PDAC adopted its e3 Plus principles, a framework to guide its membership in responsible exploration.

Jan 1, 2011

By Van E. Housman, Stephen D. Hoffman

The Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), also known as "Superfund", requires a listing of sites that have known releases or threatened releases of hazardous substances, pollutants, or contaminants throughout the U.S. When EPA determines that a significant threat exists, it places the worst contaminated sites on the National Priorities List (NPL). CERCLA provides EPA broad authority to clean up hazardous sites that threaten human health and the environment. There are currently 52 sites on the NPL that were placed on the list because of high human health or environmental risk as a result of non-coal mineral extraction, beneficiation, or processing operations. This list covers mining sectors from aluminum to zinc. While some of these sites were abandoned, many are still operating. (There are additional mine sites that have been recently proposed to be included on the NPL that are not included in this paper.) EPA is continuing to develop a mining program to address human health and environmental threats from active non-coal mines. EPA has performed a comprehensive study to assess the waste management practices at all of the 52 mine sites on the NPL. In addition, EPA is continuing to collect information on the specific mining sectors (i.e., gold, copper) that represent many of the NPL mine sites. One of the goals of this effort is to attempt to identify the types of mining practices that lead to human health and environmental problems at the NPL mine site. EPA estimates that there are currently 500 to 1,000 active mines (not including placer operations). While some mining NPL sites began operations before the turn of the century, only a handful of the NPL mines entirely ceased operations prior to 1970. Of the 52 NPL sites studied by EPA, 12 are currently active. By definition, these mines represent current mining practices. Approximately 17 additional NPL mines that ceased operations between 1970 and 1990 represent some degree of current mining practices. Therefore, at best, less than half on the 52 NPL mine sites can be said to definitely represent past mining practices. Although some mining waste management practices have changed over time, the basic technology for extraction and beneficiation of mineral ores have remained fairly constant over the last fifty years. While the use of acid to leach copper dumps, the use of cyanide to leach gold in heaps, and the spread of solvent extraction techniques has changed some aspects of mining, the basic operation of removing ore from the ground and concentrating it through beneficiation has remained fundamentally the same as when most of the non-active

Jan 1, 1992

By Valeh Aghazadeh, Shima Barakan, Mina Soleymani, Ehsan Bidari, Morovvat Faridazad

Molybdenite is the most important molybdenum concentrate, which is mainly recovered as a by-product from porphyry copper deposits. Due to the low efficiency of purification processes such as flotation in the reduction of copper content of molybdenum concentrate to a standard level (i.e., less than 0.5 wt.%), further purification by a hydrometallurgical method is required. Although different types of chemical reagents were found to be effective in the leaching of copper minerals from molybdenum concentrate, the mechanisms of these processes remain largely unexplored. In this study, optimal conditions for maximum copper leaching (> 99%) were obtained at the concentration of HCl = 1 M, FeCl3 = 0.5 M, CuCl2 = 0.05 M, CaCl2 = 0.5 M at 75 °C, 500 rpm, and S:L = 1:10 during 60 min. CuCl2 was identified as the most effective leaching reagent for copper dissolution in agreement with Visual MINTEQ model results due to the formation of various types of copper chloride complexes. Furthermore, the electrochemical behaviors of FeCl3, CuCl2, and CaCl2 reagents before and after the leaching process were investigated by the cyclic voltammetry technique. The results of cyclic voltammograms at different scan rates verified the presence of copper chloride complexes, and ferric ions as the oxidizing reagents for better dissolution of copper sulfides. Based on kinetic study results of shrinking core models, both chemical and diffusion reactions controlled the copper leaching process with an obtained activation energy of 33.56 kJ/mol. For recovery of the leached copper, the precipitation process was done by the addition of Na2S at 45 °C, S/Cu = 1, and pH = 9.

Dec 26, 2022

By W Medina, G Angulo, A Anani

A current challenge faced by the mining industry is solving the integrated transition mine problem (TMP) that maximizes the net present value (NPV). This study aims to develop an optimization framework capable of solving the TMP. The problem is NP-hard and therefore computationally intractable. Three ad hoc approaches – Exact solution, Benders’ decomposition, and Benders’ decomposition with Bienstock-Zuckerberg (BZ) algorithm – are compared for different scheduling periods. The TMP is formulated as a mixed integer linear programming model, implemented in Python, and solved with the Gurobi optimizer. The results showed that Bender's decomposition with the BZ algorithm outperforms the other approaches in execution time, computational cost, and feasibility to address large problems in exchange for a marginal cost in the quality of the NPV obtained. In addition, the probability of finding the optimal point of transition is higher regardless of the number of feasible crown pillar locations evaluated. This is achieved through the optimality cuts proposed in the algorithm.

Jun 25, 2023

By Joseph M. Driscoll

After 30 years of successfully mining gold, Newmont Gold has temporarily ceased production from the original Carlin Pit. In late 1993, the Carlin East decline was driven and an extensive underground exploration program was started. Today, Newmont Gold produces refractory ore from the Carlin East Underground at the rate of 864 t/d (950 stpd). Annual production is more than 3.1 t (100,000 02). More than 70 underground miners will be employed during Carlin East's estimated six-year mine life. About 70% of the ore at Carlin East is mined by mechanized longhole stoping with delayed, cemented backfill. The remaining ore is mined by underhand drift and cemented fill methods.

Jan 1, 1997

By Tyler Acorn, Brandon Wilson, Jeff Boisvert

Project-scale decisions in surface mining operations rely on the optimization and subsequent evaluation of pit limits. This process ignores the ability for mine plans to adapt as more information is gathered. Stochastic methods, which consider uncertainty in the pit optimization, generally act to refine the boundaries of the pit on a fine scale. This paper extends uncertainty-based methods to consider unique scenarios through a clustering of the realizations that are being optimized. This results in the generation of multiple sets of similar realizations. A separate pit is optimized on each set of realizations, resulting in the production of a series of planning scenarios. This accounts for the adaptability of mine planning as more information is gained. A decision-making framework is then applied to the resulting scenario plans to select the optimal choice. The improvements stem from the joint uncertainty considered when realizations are grouped that is not considered when the probability of a block being in any optimized pit is considered. Mining operations today can benefit from considering additional planning options as identified and evaluated in this workflow.

By Duane L. Abata

Toxic gases produced by the detonation of six explosives were measured in an underground hardrock metal mine during actual mining operations. The six explosives included two semigelatin dynamites, three slurry explosives and an ammonium nitrate, fuel-oil/ammonia dynamite combination. Explosives were detonated at the face of a drift and the toxic gases produced by the detonation were trapped to the end of the drift by a bulkhead located a short distance away from the face. Toxic gas concentrations were then measured with direct readout instruments and together with the containment volume, the toxic gas volumes per mass of explosive were calculated. Toxic gas measurements were found in the following ranges (ft3/lbm): NO, 0.010-0.035; NO2, 0.003-0.019; CO, 0.08-0.30; S02, 0.00-0.05; and CO2, 0.7-1.8. Results showed that toxic gas production (ft3/lbm) correlated with the densities (kg/m3) and energy densities (kJ/kg) of the explosives tested.

Jan 1, 1979

By John E. Frost

Duval's (now Battle Mountain Gold Co.) copper and gold deposits in the Battle Mountain District in Nevada are in two subdistricts - Copper Basin and Copper Canyon - about 18 km (11miles) apart. Location of the two subdistricts is shown in Fig. 1. The two centers of mineralization have distinctive geologic and ore characteristics that required different innovative approaches to exploration and development. Nearly all of the copper from Copper Basin has been recovered by heap leaching. Because of relatively high gold and silver values in the Copper Canyon ores, a significant part of the sulfide copper ores has been recovered by a conventional flotation mill at Copper Canyon. Recently, this mill has been converted to the recovery of gold that is mined from zones peripheral to the copper deposits. Prior to Duval's entry, small amounts of copper, gold, silver, lead, zinc, and antimony had been mined in the district over a nearly 100 year period, beginning in 1866. The bulk of the $13 million total production to 1962 was derived from copper and gold lode ores and gold placers. Duval's interest in Battle Mountain-arose directly from a submittal by Asarco, which controlled key claims in both the Copper Basin and Copper Canyon subdistricts. Asarco acquired its holdings in the district in 1959 and undertook limited exploration until mid-1961. At that time, the company decided to dispose of its interests. Duval was invited to evaluate Asarco's properties and accepted. On Dec. 6 and 7, 1961, J.E. Frost, R.C. James, R.W. Sayers, and H.A. Schmitt, representing Duval, and K. Richard and E.W. New- man, representing Asarco, visited Copper Basin and Copper Canyon. Frost concluded that the properties were of considerable interest and prepared, by Jan. 12, 1962, a voluminous report recommending that Duval acquire and explore Asarco's properties. Furthermore, he recommended a large initial exploration program that included not only geologic mapping, geochemistry, and geophysics, but also the extensive drilling that was to involve, as the first phase of exploration, 49 drill holes in Copper Basin and 21 drill holes in Copper Canyon. Following property agreements between Duval and Asarco, and Duval and several other claim owners, geologic mapping, geochemical surveys, and drilling began in August 1962. Exploration drilling was completed in July 1964 and engineering studies in April 1965. Development of the Battle Mountain properties was authorized in July 1965, and production commenced in the first quarter of 1967. Because of the unusually high oxide copper content of the ore bodies, particularly in Copper Basin, a much larger than typical proportion of the copper in the deposits has been recovered by heap leaching. The generalized geology and ore zones of the Copper Basin are as shown in Fig. 2 and of Copper Canyon in Fig. 3.

Jan 1, 1991

By Ryan C. Stephan, Zach Agioutantis, Christopher Mark

During the past 15 years, roof fall rates have fallen dramatically in US coal mines, particularly in regions where the roof is weakest. The remarkable reduction in the number of roof falls has been accomplished with more effective roof support systems. The purpose of this paper is to present a design methodology that builds on and quantifies the basic roof support concepts that have been successful in the USA. The methodology starts by defining three modes of roof support, based on the roof strength relative to the stress level: (1) suspension, where roof bolts mainly provide skin control for strong roof; (2) beam building, where moderate strength roof can be supported by roof bolts alone; and (3) supplemental support for weak roof. Next, a large database of roof fall histories at a number of mines is used to define the approximate boundaries of these three regimes based on the coal mine roof rating and the depth of cover. Finally, guidelines are presented for site-specific design of support systems within each regime. The new computer package, analysis of mine roof support (AMRS), implements the design methodology.

Sep 29, 2020

St. Peter sandstone is an arenaceous sheet that covers large area in North America. The interest for St. Peter sandstone has been increasing due to the upward trend for hydrofracturing and the consequent need for fracking sand. This material is possesses very unique mechanical properties. On the one hand, it is brittle as characterized by an unusually high friction angle, up to 69°, and steeply curved failure envelopes. On the other hand, it is friable, possessing extremely low, and in most cases zero cohesion. The underground mines that are working under this condition are lacking the ground control techniques for this particular mining environment. The geotechnical properties of the St. Peter sandstone were examined using uniaxial test, triaxial test, porosity test, flexural strength test. This paper aims to investigate the effect of microstructure on strength properties, utilizing microscopic studies, index test (porosity, size distribution).

Feb 23, 2014

By Nawal Kishore, Nilesh Pratap Singh, Amit Kumar Verma, Vikram Seervi

In India, demand for coal exceeds its countrywide supply, despite its natural abundance, due to failure to achieve high production targets, especially in opencast mines, which are responsible for 94.98% of total raw coal production within the country. Employment of technological solutions, such as surface miners, is key to achieving higher coal production and productivity in an eco-friendly manner, especially in the populated areas adjacent to the mining zone and, hence, require restricted blasting operations. It eliminates blast hole drilling, blasting, and primary crushing units, thus reducing related environmental hazards like ground vibration and fly rocks. This paper encompasses the applicability, advantages, constructional features, and performance assessment models for each working mode of a surface miner. The current paper discusses the correlation between coal production and key productivity indicators, namely, machine shift-time, pick, and diesel consumption of surface miner in three different geo-mining conditions. Furthermore, relationships between machine shift-time, pick, and diesel consumption of surface miner and coal production were evaluated through bivariate regression analyses along with their coefficient of determination. These key productivity indicators of surface miner follow polynomial relationships with coal production on a daily and monthly basis, having Pearson correlation values from 0.774 to 0.907 and coefficient of determination, from 0.664 to 0.909 in opencast coal mines.

Jan 20, 2023

By Xin Wang, He Shao, Wenpu Li, Yiyi Zheng, Xi Chen, Yurong Gao

This study utilized experimental and numerical simulation methods to investigate and analyze the atomization characteristics of three internal air–water mixed atomizers under different operating conditions. By comparing the research results, the effective dust control working parameters for the application of the selected atomizer in the engineering field were determined. Firstly, the atomization characteristics of the three atomizers were studied using a customized experimental system. The results indicated that nozzle 2 had a wide atomization range, a small atomization distance, and small droplet size; nozzle 3 had a narrow atomization range, large droplet size, and fast atomization speed; and nozzle 1 not only had a large atomization range but also could produce droplets of dry mist size with fast atomization speed, meeting the dust reduction requirements of the Majiliang Coal Preparation Plant. Secondly, Fluent software was used to simulate the atomization process and particle size distribution of the three internal mixed atomizers, determining the working conditions of the atomizers, the required number of atomizers, and the application angle of the atomizers in the internal mixed dust removal system. Finally, the atomized dust control system was applied on-site, achieving a total dust removal efficiency of 90.72% and a respirable dust removal efficiency of 89.75%.

Mar 9, 2024