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By Joel Lööw, Jan Johansson, Lena Abrahamsson

In this study, we try to illustrate what new technology can mean for the individual miner. We formulate the notion of Mining 4.0, where we attempt to create an image of how the future might look from a miner’s perspective and how mining companies might navigate their way to a future that works for all miners. 

By Rodrigo Estay Huidobro, Andrés Martinoli, Claudia Pavez-Orrego

The effects of induced seismicity caused by mining activities are one of the main problems that the mining industry faces. Although it has been documented by countries with a great mining tradition (United States, Canada, Australia and Chile) for over a century, the problem has been intensified throughout the years due to the greater depths that mineral extraction reaches, where the stress levels and environmental conditions increase the possibility of a rockburst occurrence. Seismic events inside the mine cause important losses of human lives and infrastructure damage. To deal with this problem it is necessary to implement several kinds of safety protocols. For example, seismic indicators allow to identify, through the analysis of a set of seismic parameters -magnitude, energy, time, decay rate, among others-, periods of time when a seismic event of considerable magnitude is most likely to occur. The objective of this work is to use the frictional energy generated by a microearthquake inside the mine as a seismic indicator, linking it with the occurrence of large magnitude seismic events which are outer the background activity. Thus, we seek to determine the set of seismic parameters which allow the best performance of the frictional energy/heat indicator. In the present study, we considered magnitude, frictional energy, and time as seismic parameters to study the efficiency of the proposed indicator. The optimal set of parameters was determined using two different methodologies: accumulated thermal energy and alert bands. The Piece Skill Score and the Accuracy indexes were used to evaluate each set of parameters. Both approaches show a high rate of true positive and true negative hits. Furthermore, it was concluded that both methods show complementary results in terms of the detection of critical events (Mw > 3.0).

Apr 26, 2022

By J. F. T. Agapito

Significant economic benefits can result when rock mechanics is applied within a practical framework and integrated within the other engineering functions of the mine organization. This requires management support and understanding of rock mechanics as a practical tool to help attain high standards of safety, productivity and resource recovery. For such an approach, a long-term geotechnical program is needed in most operations to build an adequate data base and to ensure that design and ground control issues are handled in a cost-effective manner. This paper presents a summary of four case studies where significant economic benefits were realized with the help of rock mechanics. Although cost savings were not computed, the economic benefits are obvious and clearly impacted the mine operations favorably.

Jan 1, 1990

By Paul Richardson

This paper will review several projects completed during the period from 1976 through 1984 which have been carried out utilizing big hole drilling concepts. The projects discussed will be from various industries to demonstrate the extent that big hole drilling methods are being used along with the current state of development. There will be a discussion of projects planned for the future where big hole drilling methods are the only technology being considered. Also included in the discussions will be an overview of the most recently completed heavy oil recovery project. During the next decade, big hole drilling methods will be used more and more in all industries where underground access is required. The safety, speed and economics associated with shaft sinking using drilling methods are becoming more and more recognized and the technology is rapidly becoming an accepted shaft sinking method.

Jan 1, 1985

By Neil Williams

The brecciated dolostone-hosted (Mississippi Valley-type) and associated shale-hosted stratiform Pb-Zn deposits at McArthur River occur adjacent to a major syndepositional fault, the Emu fault. Base-metal zoning, mineral parageneses, and Pb and stable isotope ratios indicate that both types of deposits formed contemporaneously from metalliferous brines that flowed into the host sediments from the Emu fault. Derivation of brines from underlying evaporitic sediments is suggested. Geochemical evidence indicates that the mechanism of ore formation was sulfate-reduction coupled with oxidation of organic matter. The textural relationships of stratiform sulfide mineralization to diagenetic dolomite concretions, chert blebs, volcanic glass shards, and inter-ore breccia beds, indicate that the reactions proceeded diagenetically within about 100 m of the sediment/water interface.

Jan 1, 1979

By C. Treworgy, C. Chenoworth

Geologic and technical factors such as coal seam thickness, stripping ratios, roof conditions, partings, faults, and size and geometry of the reserve block greatly impact the availability of Illinois coal for mining. Residential and commercial developments also restrict access to coal reserves in some areas. Despite the collective effects of these factors, large blocks of bituminous coal reserves suitable for efficient, low-cost underground mining remain available in Illinois.

Feb 24, 1997

By Richard M. Crowell

"As thorough sampling is usually expensive, the cost of a complete job is often unwarranted, and a cheaper approximation must be substituted. The engineer should, however, weigh the situation thoroughly before subscribing to an alternative other than an accurate assay basis on which to build his conclusion." Examination and Valuation of Mineral Property. R. Parks, 1949

Jan 1, 1994

By G. L. Smit

The Buffelsfontein Gold Mining Company is situated in the Klerks-dorp district of the Province of the Transvaal in the Republic of South Africa, approximately 100 miles west of Johannesburg. Gold production commenced in January 1957 and Uranium treatment of residue slimes as a by-product started in July 1957. The mining property is 5435 mining claims in extent, the equivalent of 7,988 acres or 12.5 square miles. The mine was initially exploited by the Pioneer Twin Shaft System, consisting of a 26 feet diameter down-cast shaft and a 22 feet diameter up-cast shaft, sunk in the north-west area of the mine to cater for the hoisting and ventilation requirements for a milling rate of 150,000 tons per month.

Jan 1, 1964

By D. J. Frey

While costs of most commodities and services have increased markedly over the past 25 years, the cost of electricity has steadily declined. One of the reasons for this price decline is the improved efficiencies of generating plants which is shown in Fig. 1. 1,2 Another reason for this is the decline in coal production costs. Efficiencies for the best plant increased from about 32 percent in 1540 to about 40 percent in 1962 and then decreased slightly to 38 percent in 1965. The increase in efficiency for all plants (US average) has been even more notable, progressing from less than 15 percent in 1940 to about 32 percent in 1965. The chief reason for the improved efficiency is the change in operating steam temperatures. These increased about 12 F per year until 1200 F was reached in 1962. At this high temperature excessive corrosion of super-heater and reheater tubes was experienced and steam temperatures were dropped back to 1050 F and even 1000 F in some cases. To successfully compete against other energy sources for generating electricity, this corrosion problem must be solved so that operation at higher temperatures and thus, increased efficiencies will be possible.

Jan 1, 1967

The 2014 George A. Fox Conference at the Graduate Center, City University of New York in New York City was presented under the theme, ?21st Century Challenges for the Tunneling Industry. Bruce Grewcock, chief executive officer and president of Peter Kiewit Sons? Inc., opened the conference with a keynote address in which he set the tone for the rest of the day by touching on the many challenges the industry is facing, which are plentiful and complex. Covering the breadth of the industry, he spoke about everything from the technical challenges that come from working beneath the streets of some of the most densely populated regions in the world to the challenges that come from working with the people who live in those areas. ?My observation is that we, as an industry, are being asked to put structures in places where they are needed, but are complex environments to work in,? said Grewcock. ?We work in an industry that relies on some of the most technically challenging engineering in the world, and when we are done with a project, we cover it up and no one ever sees it.? Despite these issues, Grewcock said that, in his opinion, the biggest challenge the industry is facing is that of people; more precisely, where to find the next batch of people. Looking out at the conference-record crowd of more than 400 registered attendees, Grewcock quipped that he saw plenty of gray beards and asked aloud, ?Where will we find, educate and train the people to tackle the issues that this industry will face in the future??

Mar 1, 2014

By S. Kawatra, K. Lewandowski

Heap leaching efficiency is reduced by poor solution flow characteristics (channeling and ponding), which result from fines migration. Agglomeration of the ore can 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”. We have developed procedures to quantitatively determine whether a binder gives good performance in an acidic solution, and have identified several binders that will be suitable for copper heap leaching.

Jan 1, 2007

By L. Yan, N. Damiano, J. Bickson, E. Bauer, D. Yantek, B. Whisner, M. Reyes, J. Srednicki

Built-in-place (BIP) refuge alternatives (RAs) are designed to provide a secure space for miners who cannot escape during a mine emergency. Heat and humidity buildup within RAs may expose miners to physiological hazards such as heat stress. To minimize the risk of heat stress, Title 30 Code of Federal Regulations (CFR), or 30 CFR, mandates a maximum allowable apparent temperature (AT) for an occupied RA of 35°C (95°F) [1]. The National Institute for Occupational Safety and Health (NIOSH) has conducted extensive research on the thermal environment of occupied RAs intended for use in underground coal mines. NIOSH research has demonstrated that a fully occupied BIP RA can exceed the AT limit by >5.6°C (10°F) in mines with elevated mine strata and air temperatures. In this circumstance, an RA cooling system could provide a solution. This paper provides an overview of test methodology and findings as well as guidance on improving the performance of a cryogenic air system prototype by optimizing the flow rate, increasing the tank storage capacity, and improving the efficiency of the heat exchanger of the cryogenic system. This may enable BIP RAs to meet the 35°C (95°F) AT limit in mines with elevated temperatures. The information in this paper is useful for RA manufacturers and mines that may choose to implement a cryogenic air system as a heat mitigation strategy. INTRODUCTION The apparent temperature inside an occupied RA could be significantly affected by the surrounding environment’s thermal conditions, such as mine air temperature and mine strata temperature. Apparent temperature (AT) is a temperature-humidity metric for the perceived temperature caused by the combined effects of air temperature, relative humidity (RH), and air velocity. It is used to assess the perception of indoor temperatures. Depending on factors such as geographic location and season, mine air temperature, relative humidity, and mine strata, temperatures can vary significantly [2]. RAs located in cold mines may pass the 96-hour 35°C (95°F) AT limit test that poses a challenge for RAs located in hot mines. One solution in these cases is that the occupancy of the RA could be derated (i.e., the RA occupancy could be reduced) to ensure the AT limit is not reached. However, this would require mines to purchase additional RAs to accommodate all personnel in the mine. For mines with high temperatures (above 26.7°C or 80°F), the occupancy might have to be reduced so much that the necessary number of additional RAs would be impractical. In these cases, RA cooling systems could provide a solution.

Jan 1, 2019

By J. L. Workman

The stability of spoil and highwall slopes are important to successful strip mining. This paper discusses soil parameters of importance in stability analysis. The common mechanisms of spoil failure are discussed. Modes of highwall failure are also outlined. The importance of water to stability is presented. Dragline mining methods most suited to creating spoil and highwall profiles that address stability needs are provided. It is concluded that groundwater and surface runoff must be well controlled, and that it will often be necessary to modify spoil and highwall configurations to achieve a stable overall slope angle.

Jan 1, 1996

By Florence Ntsiful, Eric Stemn

Exposure to whole-body vibration has been recognised as an occupational hazard in the mining industry, especially in the operations of earthmoving equipment. Managing whole-body vibration exposures requires periodic measurement of exposure levels to identify priority areas for implementing controls. However, due to different approaches to collecting exposure values, significant variabilities lie in the results. This systematic review is the first attempt to analyse whole-body assessment methods in the mining industry. The aim was to identify how whole-body vibration has been assessed, including the sources of variabilities to improve future research. The PRISMA methodology was adopted for the review and a total of 152 peer-reviewed journal articles were identified. However, only 24 were included in the review, following the application of some inclusion criteria. Descriptive and thematic analyses were performed on the 24 selected articles. Results indicate that whole-body vibration has been assessed as a function of either equipment characteristics, activity undertaken, operator characteristics, measurement approach or the assessment standards. Due to the multifactorial and dynamic nature of wholebody vibration exposures, the variabilities in results are due to the interrelationships between the risk factors of whole-body vibration and the differences in the sample sizes. To identify the sources of variabilities, a comprehensive assessment of all the risk factors, including equipment characteristics, road conditions, operator characteristics, and activity undertaken, is highly warranted. Finally, research gaps and directions for future research have also been discussed.

Dec 21, 2022

By D. D. Faulkner

Cable bolts anchored with traditional two component polyester resin cartridges have successfully supported difficult roof conditions in underground mines. Resin cartridges provide a cost-effective cable bolt anchoring system with consistent anchorage performance characteristics when properly installed. The most commonly used cable bolts in the U.S. mining industry are 270 ksi (1,862 MPa), 0.7 and 0.6 inch (18 and 15 mm), seven-strand smooth cable with resin mixing bulbs (also known as bird cages), and 40- and 30-ton nominal capacity, respectively. However, there are other types of cable bolt anchoring systems aside from bird cages. Recently, many questions have been raised regarding the anchorage characteristics of various types of cable bolts. Keystone Mining Services, LLC (KMS), the affiliated engineering company of Jennmar Corporation, conducted a variety of controlled tests developed to closely model actual underground installations. These tests compared the performance of three commonly used cable bolt varieties, including plain, bird caged and indented seven-strand cable. Details of the laboratory testing and comparative analysis of the results are provided.

Feb 23, 2014

By A. K. Raina

Blast induced damage to the final wall of rockmass in any civil or engineering application is a major concern to the rock excavation engineers. There are at least four distinct techniques practised by blasting engineers to minimise the damage to the parent rock during blasting that are classified as contour blasting. One of the methods to achieve a smooth wall or rock surface in blasting is pre-splitting, where blastholes in the final row are mildly loaded with explosives and fired first in sequence before the rest of the holes in a round of blast to achieve a split in rockmass. Since blasting is one of the most adopted methods for achieving a final wall in a desired shape, while maintaining the rockmass integrity, the design of pre-split blast assumes importance. There are several variables that determine the final shape of the pre-split face including the rock type, the drill diameter, the explosive characteristics, the orientation of major joints with respect to drill hole, the linear charge density, the spacing of drill holes and inclination of the drill holes. This study attempts to determine the importance and sensitivity of variables in pre-split blasting using historical data from open excavations of a hydroelectric project in India. Keeping in view the multitude of variables, low correlation of independent variables with responses and high level of interactions between the variables that define the blast results, it was found suitable to use ANN to determine the importance and sensitivity of the variables involved. A new method to determine the blast induced damage to rockmass, namely, undamaged area (AUD%), is introduced. Half Cast Factor (HCF%) and AUD%were calculated for a high wall and trenches by digital image analysis technique using the Fragalyst software. Joint spacing and linear charge density emerged as most controlling variables in determining the final result of pre-blast. The relative importance of other variables assuming significance in the case of both the designed outputs is also discussed. A comparative analysis of HCF%and AUD%on the basis of results obtained from ANN analysis is also presented. A futuristic approach concept has also been introduced.

May 30, 2021

By C. Xiao, R. Chi

In recent years, the biosolubilization of rock phosphates by phosphate-solubilizing microorganisms has become a major topic of research studies. However, the microorganisms used in previous studies were mostly single and known species, and studies seldom focused on mixed communities of microorganisms or microbial consortia from natural environments. In this study, a microbial consortium from rhizospheric soil was used to solubilize two different compositions of medium- to low-grade rock phosphates — designated as ore samples 1 and 2 — in a laboratory-scale bioreactor. The microbial consortium showed good growth in the bioreactor, reduced the suspension pH and released soluble phosphates from the ores. Scanning electron microscopy with energy-dispersive X-ray spectroscopy showed the action of the microbial consortium on the ore surface. There was considerable corrosion on the ore surface, and 3.42 and 4.93 percent of the element phosphorus was removed from ore samples 1 and 2, respectively. Microorganisms were sampled from the bioreactor for the analysis of their community structures by Illumina MiSeq high-throughput sequencing. The analysis show that the suspensions added with different ore samples had different microbial diversities and richness. This study provides new insight into the biosolubilization of rock phosphates by a microbial consortium directly taken from rhizospheric soils.

By J. W. Motter

Currently, virtually all new electric power generation systems under construction are designed with natural gas as the primary fuel. Factors driving these construction decisions involve sustained low prices for natural gas, environ-mental (and consequent regulatory) risks associated with the use of coal for power generation, and relatively high costs of construction for conventional coal-fired power plants. Despite the unarguable abundance of coal in the US. and worldwide, a fundamental question arises: What will be the role of coal in electric power generation in the 21st century? Congress, recognizing the vital and strategic importance of preserving the coal option for electric power generation, authorized the Clean Coal Technology Program. This pro-gram, with original funding in excess of $2,500 million, is intended to promote the demonstration and commercialization of a new generation of clean, efficient coal-based energy technologies through collaboration and partnering with private industry. The two technologies being demonstrated under this program which are the key to the continued use of this nation's huge coal reserves are coal gasification and the pressurized fluid bed. Either or both of these technologies, coupled with a combined cycle will pro-vide the continuing future coal option, while responding to increasingly more restrictive environmental standards. Recent Congressional budget-cutting efforts, however, could threaten the effectiveness of that model program, and ultimately other subsequent government-industry collaboration.

Jan 1, 1996

By J. S. Hu

FTIR spectroscopy has been used for the characterization of adsorbed oleate at the fluorite surface. It has been found that modest changes in the adsorption density at high temperature and high oxygen potential do not provide a satisfactory explanation for the significant increase in the hydrophobic character of the system under similar conditions. Rather, FTIR spectroscopic measurements suggest that chemical interaction between adsorbed oleyl groups occurs at high temperature and/or oxygen potential and accounts for the increased hydrophobicity. Specifically, the intensity of the =CH bond of the adsorbed oleate diminishes at high temperature and/or high oxygen potential. Such a phenomenon was not observed in control tests with the calcium oleate soap. For extensive reaction at the fluorite surface, the presence of a new surface species has been identified. These results indicate that the fluorite surface catalyzes an oxidation and/or polymerization reaction between adsorbed oleyl groups which results in a more hydrophobic structure at the fluorite surface.

Jan 1, 1986

By M. Z. A. Bakar

A series of full scale laboratory linear rock cutting tests was carried out with a long bladed single disc cutter (292 mm diameter, 11mm wide constant cross-section blade) on dry and water saturated sandstone blocks using a linear rock cutting machine (LRCM). The muck collected from the cutting tests has been analyzed to establish a link with the specific energy (SE) of the operation. Coarseness index (CI), a non dimensional parameter, has been found to be a useful indicator of the relative efficiency of the cutting operation. An inverse relationship of the form SE = k CI-n is observed between SE and CI with very high CI usually corresponding with the lowest values of SE. The power n of the relationship for both dry and saturated rock tests is much less than the values found in the previous studies using constant cross section disc cutters and is believed to be dependent on the strength of the rock and the cutter type used. Although the average CI is found to be lower for saturated rock than for dry rock, at the same time saturated rock cutting is found to be less energy intensive (in terms of SE) than dry rock cutting. Moderate correlation exists between the production rate or yield and the SE of the cutting operation for both dry and saturated rock, which can provide some useful information about the field production rate discounting the effect of discontinuities in the rock mass.

Jan 1, 2012