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By K. J. Ashley

Over the last six years I have been involved with the calculation of ore reserves and mine planning using various computer systems and soft- ware packages. This experience has given me a unique perspective from which to view the needs of the engineers and geologists whose job it is to produce geologic and mineable ore reserves. The purpose of this paper is to share that perspective with those who are in this field or are thinking of purchasing computer software to aid in these calculations. My first experience with computers in mining was the creation of a mini-computer based coal reserve and mine planning package written as part of my Easter's thesis. This package took about ten weeks to write, four weeks to document, and two weeks to install at the mine for which it was written. It did what it was designed to do, which was to emulate the hand procedure which had been used prior to its installation. The package was specific to its application which involved several small seams of coal being mined simultaneously and would have required major modification for it to be applied to a mine where, say, one thick seam was mined in two benches.

Jan 1, 1985

By B. M. Eiter, J. Hrica, D. R. Willmer

"Mineworkers are routinely tasked with making critically important decisions about whether or not a hazard presents an imminent danger. Researchers from the U.S. National Institute for Occupational Safety and Health collected formative data to investigate mine safety professional perspectives on workplace examinations, which revealed a potential gap in how mineworkers are assessing risk. During interviews, participants revealed not having a systematic methodology for mineworkers to use to determine if a hazard is considered imminent danger. In this paper, we identify and describe three distinct categories of imminent danger complexity and discuss potential steps that could lead to improved identification of imminent danger situations. Finally, we identify potential practices to incorporate into risk management efforts, including feedback, communication and specialized training, to increase awareness of imminent danger situations. IntroductionIn recent years, the metal and nonmetal mining sector, as categorized by the U.S. Mine Safety and Health Administration (MSHA), experienced an increase in the number of fatalities occurring at mine sites. From 2013 to 2015, 69 mineworkers were fatally injured, twice the number of fatalities in each of the previous two years (MSHA, 2015a). As a way to address this increase, MSHA issued its P15- IV-01 program policy letter, suggesting that “miners would benefit from rigorous workplace examinations conducted by experienced and trained examiners” (MSHA, 2015b). The goal of these examinations is to find hazards in the field and mitigate them before they cause injury or death to mineworkers. While it is important to identify all hazards in the workplace, it is critically important to identify those hazards that are considered imminent danger because they require an immediate response to avoid a severe or even fatal injury."

Jan 9, 2018

By B. Boutilier, R. Mendoza

"First Majestic Silver Corp. (FMS) is a silver mining company founded in 2002 that operates exclusively in Mexico. It has six producing silver mines, one of which is the La Encantada silver mine (La Encantada) located in the state Coahuila. La Encantada is located near the southern United States border and 708 km (440 miles) north of the city Torreon.La Encantada is located in the Sierra Madre Oriental and is a high-temperature carbonate replacement deposit. Mineralization in La Encantada occurs in many different forms such as veins, chimneys, breccia pipes and reefs (mantos). Mineralization is mainly oxides of iron, zinc, lead and manganese, with high concentrations of sulfides at depth relating to two main intrusive events: the Milagros Intrusive and the La Prieta Skarn.Mining began in La Encantada during the 1950s with small vertical shafts, drifts and raises. It focuses on the high-grade silver zones using traditional hoists and extraction methods, before branching into two main separate mining camps: El Plomo and Penoles camp. Penoles, the previous owner, focused mainly on large ore bodies using post pillar cut-and-fill mining method to extract the higher-grade material. Due to the type of ground, irregularity of pillars, and rock conditions, large amounts of high-grade pillars had to be left in situ to ensure the stability of the excavations. The mined-out areas would then be filled with lower-grade material to assist in the stability of the secondary level. These room-and-pillar development entries were 2.5 m x 2.5 m (8.2 ft x 8.2 ft) and spaced every 10 m (32 ft), leaving a vertical pillar of 7.5 m (25 ft). First Majestic acquired La Encantada in 2006. After the acquisition of the mine, the company began the conversion of the surveying reference system from a local grid (Maria Isabel Shaft as 0,0) to the Nav27 coordinate system, and subsequently converted to the WGS84 coordinate system in 2015. Due to the extensive history of the mine, different areas were surveyed with different systems, causing significant challenges when designing the principal extraction levels, pillar heights and ramp locations. To overcome this difficulty, the entire mine was resurveyed and the old workings transposed to the new coordinate system, except for some inaccessible areas due to poor ground conditions or ground collapses. To further ensure pillar height and the safety of the mine workers, probe holes were drilled during the development process."

Sep 1, 2019

By R. B. Elver

The level of steel consumption per capita is one of the principal indicators of a country's standard of living. It is no coincidence that the materially advanced nations possess viable iron and steel industries to provide a reliable and economic source of steal for the manufacturing industries. No other metal is as dominantly important in manufacturing as steel. The blast furnace - steel furnace complex based on coking coal, ferrous scrap and iron ore - continues to be the principal steel-producing method. Less important is the electric furnace method based on scrap, In recent years, there has been considerable interest in the many direct reduction processes that are not dependent on coking coal but usually produce a product for further refining in steel furnaces. No matter which series of processes are used, iron ore is essentially the only source of virgin iron units. Thus, to such a vital and capital-intense industry as steel, access to a relatively inexpensive, long- term supply of iron ore is essential.

Jan 1, 1964

By S. Hamm

Elevated total dissolved solids (TDS) content in waters downstream from surface coal mines in Central Appalachia is an increasing concern, as unnaturally high TDS and/or associated specific conductivity (SC) may contribute to deteriorated stream ecosystem health. The aim of this preliminary study was to explore the efficacy of accelerated leaching as a means of minimizing long-term TDS/SC generation by problematic overburden materials. Five spoil samples were collected and leached using simulated rainwater solutions under ambient and acidified pH conditions. SC and pH were monitored during each leach cycle, and ICP-MS was used to determine how leaching conditions affected release of specific ions. This paper highlights the results of both jar and column leaching tests. Among the most significant findings was that, for certain spoil materials, SC in leach column effluent was effectively reduced when spoil was leached first with acidic rainwater followed by ambient rainwater (vs. ambient rainwater leaching alone). This suggests that accelerated leaching might aid in long-term stabilization of some materials.

Feb 23, 2014

By Meng Li, Hao Nie, Weitian Ding, Mamdouh Omran, Ying Li, Yao Ge, Yaowei Yu, Abourehab Hammam, Lei Zan

This study examines the isothermal and non-isothermal reduction behaviors of iron ore compacts in a pure hydrogen atmosphere and compares the results obtained during the reduction process by CO. The different phases accompanying the reduction reactions were identified using X-ray diffraction (XRD) and its morphology was microscopically examined. In isothermal experiments, temperature plays a significant role in the reduction process. At any given temperature, the reduction rate during the initial stages is higher than that during the final stages. The reduction rate in H2 atmosphere was faster than in CO gas. The comparison of activation energy values suggested that reduction with H2 is more efficient thanwith CO. At the same temperature, the time required to achieve a certain degree of reduction was lower when using H2 gas than CO atmosphere. In non-isothermal tests, the heating rate has a significant effect on the reduction rate and reduction extent. At the same heating rate, the degree of reduction was higher in H2 atmosphere than in CO gas. Based on experimental data, the parameters of reaction kinetics were deduced by application of model-free and model-fitting methods. The reduction in H2 atmosphere was controlled by nucleation model (Avrami-Erofeev model), while the CO reduction reaction was controlled by gas diffusion.

Sep 29, 2020

By R. R. Dorfler

The existing regrind circuit at the Climax Operations uses sodium cyanide and Nokes reagent to reject pyrite, copper, and lead minerals. Laboratory flotation studies were performed using feed to flotation following first-stage regrinding. The effects of conditioning time, pH, and the concentration of depressants such as Nokes reagent and sodium cyanide on the rejection of pyrite, lead, and copper minerals were investigated. The metallurgical results indicate that, in the presence of depressants, the rejection of copper is strongly dependent on the pH. Preliminary mill testing confirmed the finding. The rejection of impurities is also dependent on conditioning time. The recovery of molybdenite is independent of the variables investigated.

Jan 1, 1981

By John N. Murphy

The environmental status of underground mining operations is critical to the health and safety of the miners; particularly in a large mine, the multitude of interacting parameters that can favorably or adversely affect the environ-mental status makes the manpower requirement of the routine checking of specific areas and conditions a formidable one. While the concept of environmental monitoring for miners has been considered for some time, until recently the availability of sensors to reliably measure the parameters of interest severely limited the utility of such systems. The status of sensors for mine use and the evaluation of environmental monitoring systems is reviewed.

Jan 1, 1977

By M. Z. Mubarok, Z. T. Ichlas, A. T. Sugiarto, K. Sukamto

The use of ozone as an oxidant for the direct leaching of zinc sulfide (sphalerite) concentrate in sulfuric acid medium under atmospheric pressure was explored. The influence of acid concentration, feed gas injection rate, particle size distribution, stirring speed, temperature and slurry density on zinc extraction efficiency was examined. The experimental results showed that the leaching efficiency depends on all of these operating parameters except for stirring speed. It was found that essentially complete dissolution of zinc from the concentrate with the present method can be achieved in only about seven hours under the conditions of sulfuric acid concentration of 2 mol/L, particle size smaller than 74 µm, slurry density of 50 g/L, stirring speed of 420 rpm and feed gas injection rate of 1 L/min at ambient temperature. The experimental results suggest that the dissolution reactions produce independent elemental sulfur that is readily floated and can be easily separated rather than forming a layer on the surface of the reacted particle, as usually observed in a system with ferric-sulfate as oxidizing agent. It was therefore determined that the dissolved ozone play a key role in improving the rate of zinc dissolution from the concentrate. Analysis of the leaching kinetics indicate that the leaching rate follows the shrinking particle model, and the overall dissolution rate of zinc is controlled by a surface reaction.

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

By Ping Zhang, Shahram Mozaffari, Andreas Ylmefors

The risk associated with mining induced seismicity and the related rock bursts has become one of the major threats to the safety and sustainability of mining at the Kiirunavaara mine. The causes of mining induced seismicity at the Kiirunavaara mine are very complex and have affected our understanding on the source mechanisms of seismicity and further the mitigation of the seismic risk. Detailed analysis of historical mining induced seismicity at the Kiirunavaara mine was conducted. The focus of this analysis was placed on the classification of large seismic events and the evaluation of the influential factors on the classified seismic events. 145 events with local magnitude larger than 1.5 that occurred between January 1, 2011 and March 31, 2021 were analyzed. For this analysis, seismic events located in the hanging wall were not included, as these have not been observed to cause large damages to the mine itself. It was found that the magnitude of the events had good correlation with the stress change in relation to the production location. The seismic events were classified as mining-front associated, ore-pass associated, mining-front and ore-pass associated and others, according to their hypocenter location. Most of the mining-front associated events, concentrated around the production levels and slightly above and below them, generally correlated with shear cracks, and most of them occurred when the ore flow between two production levels started. The numerical modelling showed that slip of the geological discontinuity, due to unclamping between hanging wall and footwall, could be the major causative mechanisms, which further supports this finding. The ore-pass associated events are located close to the ore passes. Large seismic events located between ore passes have the source mechanism of both fault-slip and non-shear, but events located at the outer side of ore passes were all fault-slip type. By checking with the ore pass scanning data, it was concluded that the most of the events located between ore passes could be pillar bursts. An elastic core concept has been then used to define a critical pillar width. The paper is not intended to be prescriptive but rather to initiate discussion of the possible classification of seismic events at the Kiirunavaara mine and to present new perspectives of the causes of the seismicity for improving the present seismic risk management.

Apr 26, 2022

By E. Berrezueta

Automatic digital phase imaging should yield unbiased and representative characterizations of gold ores. However, this is not a simple tusk due to low gold grade, fine grain size, possible complex mineralogy, nugget effect, etc. Using the same sections of a gold-rich ore, a critical test was performed using an optical microscope (OM) and an electron microscope (EM). In general, the two methods are consistent and useful for ore processing. There are some minor differences, such as the detection of very fine gold grains is enhanced by EM. Key words: Digital imaging, Gold ores, Mineralogy, Electron microscopy, Optical microscopy

Jan 1, 2003

By Nikhil Dhawan, Veeranjaneyulu Rayapudi

This study investigates upgrading of low-grade banded hematite quartzite iron ore (Fe ~31%). Conventional beneficiation was found to be futile. The susceptibility of iron phases to microwave exposure and their selective absorption assists in the liberation of iron values. Microwave exposure of coarse particles at 540 W for 10 min yielded a concentrate with Fe 56.30% and recovery of 50.68%. Conventional carbothermic reduction at 500 °C, 60 min and 9% charcoal yielded a concentrate with Fe 57.6% and iron recovery of 68%. The presence of sufficiently bonded silica leads to an easy formation of a fayalite phase. The microwave reduction design yielded FeG of 57.6%, FeR of 47% and a yield of 24% at an optimal condition of 540 W, 8 min and 6% charcoal. It was found that a small fraction of microwave-irradiated ore-charcoal mixture melted rapidly, and pure ferrite balls were observed within 8 min. An optical micrograph of a ferrite ball reveals the retained austenite and martensite phase.

By CHONG WEI, TATYANA KATSAGA, DEREK APEL

This study provides an effective determination process of the interface microstructural parameters in the numerical modelling of the mechanical interaction between two different geomaterials involved with frictional-bonded interfaces, such as the interaction between backfill columns and the surrounding rocks, or the soil-structure interaction, by using the coupled finite-difference and discrete-element (FD-DE) method. Three-dimensional numerical direct shear tests were conducted on the coupled FD-DE model of the combined rock-cemented rockfill (R-CRF) specimens with the frictional-bonded interface. With the microstructural parameters determined, the macro-mechanical properties of the interface of the coupled model were calibrated to well fit with the theoretical values of the combined specimen under the direct shear condition assumed according to the Mohr–Coulomb strength criterion. Evident elastoplastic shear behaviour was observed on the interfaces, and excellent agreement was attained between the shapes of the theoretical and simulated shear stress-displacement curves of the coupled models at different servo-controlled normal stresses. Particulate-scale force chains inside the DE model of the CRF specimen were highly consistent with the force contour on the FD model of the rock specimen, demonstrating the shear stress evolution of the coupled model at different shear displacements. Parametric studies verified the effects of the deformation properties of the interface parallel bonds on the shape of shear stress-displacement curves of the coupled models. The test results validated the feasibility and rationality of the coupled FD-DE method for modelling the combined specimens with frictional-bonded interfaces or joints. Furthermore, this study provides valuable numerical modelling experience for investigating the shear behaviour at the interface between cemented backfill columns and surrounding walls by using the coupled FD-DE method.

Nov 2, 2021

By Alan A. Campoli

The US Bureau of Mines (USBM) conducted research to develop improved guidelines for selecting the type and pattern of roof support in different geologic environments. The goal is to minimize the over and under design of mine roof support, resulting in more productive and safer mines. To obtain the necessary data on roof behavior and support performance, USBM conducted several field studies. Each study covers roof geology, stress regime, ground reaction, support interaction and mining environment. A consistent experimental design is being used. This includes measurements of roof bolt loads and roof movements. So far, 10 studies have been conducted in several geologic settings.

Jan 1, 1996

By U. Cetin

The Nevada Test Site is located approximately 65 miles northwest of Las Vegas, NY. The site was primarily used by the Department of Energy for the field testing of nuclear weapons and contaminated by several million cubic feet of low-level radioactive wastes, heavy metals, volatile and non-volatile organics, and explosive materials. Leaching and transportation of these contaminants are creating severe environmental problems. The purpose of this study is to examine pozzolan, a natural alumina-silicate mineral, as a possible replacement of the existing impermeable barriers (clays). In the first phase of this study, radionuclide sorption characteristics of pozzolan were investigated. This paper will present the results of the sorption tests for the target radionuclides.

Jan 1, 1998

By Jonisha P. Pollard, F. Nasarwanji, Lydia M. Kocher

This study identifies nonfatal injury incidence rates, nature of injury, work activities, glove usage, and sources of hand and finger injuries in the U.S. mining industry, as reported to the Mine Safety and Health Administration (MSHA) from 2011 to 2017. Hand and finger injuries occur at a rate of 6.53 per 1000 full-time employees, which is nearly double the rate of the next highest affected body part, the back.

Feb 24, 2022

By E. C. Wilson

The knowledge concerning the lubrication of open gearing for mining machinery has contained many unknowns and at its best has relied to a great degree on a "Rule of Thumb" procedure. It will be within the scope of this paper to explain what we have learned to date and what must be learned in the future. The results in the lubrication of open gearing have spanned the spectrum of unsatisfactory to satisfactory. With the advent of larger mining machinery, we are faced with the necessity of a more thorough knowledge of open gear lubrication. We have avail- able, better steels for the gearing, advanced technology and machinery for cutting proper tooth profiles, and better means of aligning the teeth in the gear train. This has made it possible to transmit more horsepower through the same size gear set than ever before, if we have the proper lubrication to complement the factors previously mentioned. We have set up computer programs which can calculate the data fox the tooth forms, the correct operating center distances, the contact stresses, the bending stresses, and the PVT factor of the gear teeth. This program does not, at the present, have sufficient data available to calculate the type of lubricant which should be used.

Jan 1, 1968

By Kurt M. Larson

Future haulage cost projections led Foster Yeoman Limited into developing a fully mobile crushing and conveying system at its Torr Works quarry in Somerset, England. The purpose-built system has an effective throughput of 2,500 tonnes/hour and features an Orenstein and Koppel (O & K) manufactured walking frame, a Fuller-Traylor type 54 X 74 TC gyratory crusher, and unique mobile conveyor modules designed and manufactured by Foster Yeoman. Used in a single-bench operation in this 6 million-tonne per annum limestone aggregate quarry, the system is fed at the production face by 2 Caterpillar 992C loading shovels. The entire system is moved on a daily basis following production face locations.

Jan 1, 1986

Evver since it first displayed an autonomous mining truck at the 1996 MinExpo show in Las Vegas, NV, Caterpillar has been building the blocks to a fully autonomous mine. In May, the company unveiled another block in that progression, the new Cat MineStar System that it says is ?the industry?s broadest, most comprehensively integrated miner operations and mobile equipment management system.? The full system is comprised of five capability sets ? Fleet, Terrain, Detect, Health and Command ? to help operators define the size and scope of their management system based on the needs of their mining operations. Michael Murphy, technology and autonomy manager for Cat Global Mining, explained that the customers were not ready for an autonomous mining truck in 1996, but that many customers wanted the building blocks to eventually get to autonomous mining. After 15 years of work, Murphy said the building blocks have come together in the form of the Cat MineStar System.

Jan 1, 2011