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By J. L. Brinkman

"One of the most common emissions from detonating explosives are nitrogen oxides (NOx), which are potentially deadly if inhaled. Lab studies estimate emission quantities, though great variation is shown based on site-specific conditions, and lab tests may not fully represent field results. Field VALUES (have not been measured due to the vast area affected. OSMRE recently promised to release a ruling regarding surface mine NOx production. Once the ruling is implemented, it may eventually be necessary to monitor site-specific NOx production from blasting. A small unmanned aerial vehicle system (sUAS) is able to carry a NOx gas monitor, rapidly travel to the blast location, and to follow resulting clouds of dust and emission gasses. This project will perform laboratory tests to expand on current estimations, determine an optimal method for collecting data, and evaluate the ability for this unique application of sUAS to assist in health risk assessment for mine employees and nearby communities. Additionally, large initial NOx concentrations do not necessarily correlate to unsafe conditions, and this project will be ground breaking in observance of surface blasting emission dispersion. The project is still in early phases at the time of submission for this paper (Nov 1, 2017). Therefore, this paper focuses primarily on summarizing background research related to the project and a description of the project plan. INTRODUCTION Nitrogen oxide gases (NOx) are common emission by products of surface mine blasting. These gases can potentially cause risk to human health and safety, both for mine workers and communities near the blast site. However, these emission quantities are largely unmeasured and no attempts have been made to relate these VALUES (to human health risk. The primary objectives of this project are to determine actual quantities of emission gases produced during surface blasting, to evaluate immediate and long-term risks to nearby people, communities, and ecosystems, to develop a system for mine employees to easily monitor emission and risk levels, and then provide guidelines for mitigating health risks based on a location’s emission results. BACKGROUND Current research regarding health risk produced by surface mine blasting NOx emissions is extremely lacking. Estimations have been made based on laboratory research, though these same test results show wide ranges of possible gas quantities produced based on site-specific conditions. Even if these estimations are accurate, no method has been created to relate gas quantity produced to human exposure concentrations. To further understand this field, background research was studied pertaining to blasting emission gas formation, laboratory and field measurements, harmful effects of blasting emission gases, and relevant government regulations. Background on Blasting Emission Gases"

Jan 1, 2018

By CORA ROELOFS

In the USA, miners are at higher risk for work-related disorders that could precipitate an opioid prescription, injury-related opioid prescriptions, and opioid overdose. We aimed to support prevention of these outcomes with an “opioid hazard awareness” miner safety training module. In January and February 2020, the training module was embedded within required mining safety and health training for stone, sand, and gravel miners in Massachusetts (USA). Training impact and reception were assessed with a pre- and post-training survey of trainee characteristics, training content knowledge, and attitudes. Over 800 miners were trained and over 600 responded to surveys. We found statistically significant improvements in opioid risk factor knowledge and knowledge of resources to help a coworker. Nonstigmatizing attitudes were high both at baseline and following the training. The training was perceived as relevant and useful by trainees. Improving opioid hazard awareness in high-risk worker populations has potential to reduce opioid dependence and downstream impacts including overdose death. Employer injury-prevention efforts should be reinforced while worker health and safety training enhances awareness of opioid-related harms and prevention strategies for miners and other high-risk worker populations.

Nov 19, 2021

By J. A. Herbst, H. R. Cooper, R. J. Brison, R. W. Harper, K. P. Ananthapadmanabhan, W. C. Hellyer, B. H. Bergstorm, D. M. Hopstock, H. Rush Spedden, W. C. Hellyner

Scope of Section The physical characterization of an ore or mineral mixture in such detail that mineral processing may be effectively applied to create more useful products is one part of the technology of sampling and testing. In addition, the evaluation of the multitude of separation processes, both physical and chemical, combined with ancillary opera¬tions and performed on samples at a laboratory scale, is another part of the testing procedure. Although analytical techniques provid¬ing quantitative determinations of elemental compositions are an im¬portant and necessary supplement to any testing program, that field of endeavor is a well-developed, separate entity beyond the scope of this Section. Sampling procedures cover the practice of selecting representative quantities of test materials in the field to evaluate mineral deposits, and extend to techniques of obtaining process samples in slurry and bulk ore as part of process evaluation. The same techniques are appli¬cable, of course, to standardized methods of metallurgical accounting. Sampling is also an important facet of successful on-line measurement of slurry properties such as assays and particle size in the practice of automation. However, the sampling methods in this case can be different from those needed for precise testing and accounting pur¬poses. Sampling was well defined in Taggart's Handbook as "the opera¬tion of removing a part convenient in size for testing, from a whole which is of much greater bulk, in such a way that the proportion and distribution of the quality to be tested (e.g., specific gravity, metal content, recoverability) are the same in both the whole and the part removed (SAMPLE). The conditions of the more stringent definition, that the sample shall be completely representative of the whole as regards all aspects save bulk, are practically never fulfilled when heterogenous mineral mixtures are sampled." Taggart's Handbook of Mineral Dressing, Section 19, "Sampling and Testing," continues to be a very useful compendium of principles and techniques, particularly as applied to manual methods for han¬dling samples. In the intervening years since its last revision, substan¬tial progress has been made in both the theory and the techniques; thus, this current contribution is designed to be an extension of the earlier work, yet complete enough to provide procedural guidelines to methods of continuing validity. Although basic principles of testing remain unchanged, the meth¬ods of applying those principles have undergone great change. New testing equipment has become available, yielding a greater precision of results. Testing methods have been refined which, in many cases, allows for a valid scale up of flowsheet designs without the necessity of costly pilot or prototype plant development. Justification for a Sampling and Testing Program* The proper evaluation of a mineral property is a complicated process. It often is done on a team basis with the exploration geologist, mining engineer, mineral process engineer (extractive metallurgist), economist, and product utilizer (ceramist, chemical engineer, chemist, metallurgist, etc.) all represented. The mineral processing engineer is a key member because he can provide a go no-go answer to the question, "Can this ore be processed economically?" In addition, his judgment on the response of even the initial sample to processing can be an invaluable guide to the proposed process and its mutations. Since the capital investment and operating costs are so sensitive to the type of process used, the judgment of the mineral processing engineer forms an important part of the early evaluation of the profitability of a new mining venture. This early estimation of the processing approach is all the more important since, for some metalliferous ores, the capital investment for mill, smelter, water supply, and tailings disposal exceeds the cost of the mine. At present, for commodities such as coal, the reverse is true. There is a smaller capital investment for the coal preparation plant than for the mine. In general, both the capital and operating costs escalate very rapidly in the following order: gravity concentration of alluvial deposits (e.g., dredging), gravity concentration of lode ores, flotation, simple hydrometallurgical processes, and complicated hydrometallurgical and pyrometallurgical processes. The latter two processes may cost 100 to 1,000 times more per ton treated than processing of a simple alluvial deposit. This dictates that the valuable mineral be concentrated as much as possible to minimize the total tonnage treated in the more expensive operations. Within each of these ore-processing categories there is a wide range of process sophistication and hence of capital and operating costs. Perhaps the greatest variations are in the chemical processing of ores. These range from the simple leaching of a copper waste dump to very sophisticated hydrometallurgical processing of ores in increasing order of cost. Because the overall cost of a mining venture is so sensitive to the process selected, it is essential that the mineral¬ processing engineer evaluate the ore in the initial stages of the development of an ore body. As better samples become available, he must continually revise his estimate of the process to be employed. The sampling and testing process must be a necessary and continuing activity throughout the life of a project. One fundamental aspect of nearly all mineral deposits is the inherent variability of the mineral assemblage and composition. A utopian goal of any processing plant is to have the process so flexible and so well-defined that an automatic process control system can optimize the economic recovery at all times. Since this is rarely possible, a continuing or at least a periodic testing program is desirable. Variables to be considered are: 1) Ore body inconsistencies. 2) Zonal variations. 3) Feed variations from mining plan or methods. 4) Variable performance of processing units due to wear. 5) Seasonal or other changes affecting processing conditions such as water quality, temperature, etc. 6) Changing market conditions for product quality or byproducts. 7) Technological advances in processing methods or equipment. 8) Increasing demands for environmental control. 9) Changing economics of competitive processes, of supplies, of capital investment vs. labor costs, etc. Sampling Procedures Preliminary Guidelines for Sampling Ore Deposit Studies. t At a very early stage, it is essential that the mineral processing engineer receive a sample of the ore. This may be a portion of the diamond drill core or a split from the trench, pit, churn drill, channel, or sheet sample. Even a grab sample may have some value, but it should be selected by the mining engineer or exploration geologist to be as representative of the ore body as possible within his best judgment. The sample delivered to the process engineer should have been subjected to as little prior crushing as is practical since fine sizes are difficult to concentrate. In addition, finely ground ores are readily oxidized and thus may give misleading test results. Furthermore, ground samples may make it impossible to eval¬uate either the comminution or the coarse-gravity concentration pro¬cesses. For an initial evaluation, a good deal may often be learned from a sample of only a few pounds if that is all that is available. To obtain the maximum information from a sample, its selection should be carefully discussed with the mineral processing engineer. In addi¬tion to being as representative as possible, the mineralogically distinct samples should be carefully segregated rather than composited. Since drastically different processes are often needed to process samples of differing mineralogy, considerable care and time must be exercised during this sample collection step. The segregation of samples showing gross mineralogical differences, such as the oxide caping on a sulfide deposit or a laterized zone, is easy. It is the more subtle changes in mineralogy that can often elude the field man. Yet these differences are often sufficient to dictate that an entirely different type of process be used. Obviously, the selection of these initial samples for ore testing and mineralogical studies requires that it be done by a man of consider¬able experience and judgment. While the mining engineer or field geologist is collecting these samples, he should also note and convey to the processing engineer such details as water quality and availabil¬ity, terrain, potential mill location, tailings-disposal areas, case of transportation, etc. As the property is developed with additional drill holes, adits, etc., larger and more representative samples will be required to develop the ore-processing flowsheet more adequately. If pilot-plant studies are required, a very large sample may be necessary. Though the type and amount of sample collected for flowsheet development investigations vary widely, gathering a representative sample of the ore body is a prime requisite for any process development effort. The process developed for any given ore body is only as reliable as the sample on which the flowsheet was based¬

Jan 1, 1985

By Fred Delabbio, Sverker Hartwig

As openpit copper operations transition from surface mines to underground, the speed of underground infrastructure construction prior to production is critical for maximizing the value of the project. Typically, the preferred underground bulk mining method is block caving. In preparation for future underground projects, Rio Tinto made the strategic decision to invest in a step-change program that would develop system solutions to reduce the construction time of block caves. The program focused on improving safety and doubling or more the construction speed of both vertical shafts and horizontal infrastructure compared to existing drill-and-blast rates. After an extensive selection process, Rio Tinto selected the Atlas Copco mobile miner machine as one of the concepts to proceed with for construction of horizontal infrastructure for access and footprint. In addition to un-derground drilling and hauling equipment, Atlas Copco?s Robbins mobile miner concept (a previous attempt at horizontal mechanical excavation) completed trials at Mount Isa, Pasminco and Taisei. Rio Tinto selected the new Atlas Copco mobile miner machine concept for a number of reasons including the use of proven technology from the three previous mobile miner machines and other commercial products, as well as the ability to install complete ground support typical with high rock stress conditions at approximately 1,500 to 2,000 m (4,900 to 6,500 ft) depth. Atlas Copco, with support from Rowa, the Swiss company that specializes in back up systems for tunnel boring machines (TBM), is advancing the detail design of the access version of a tunneling system on behalf of Rio Tinto. Because of the different requirements between an excavation system for access tunnels and that for tunnels on the footprint, two different versions of the mobile miner machine technology were envisioned. The access and the footprint versions of the Atlas Copco mobile miner machine share a majority of key technologies and systems. Therefore, it was possible to conduct a performance conformation test using a full-scale version of the access machine that would also mitigate the technical risks for the footprint version. To alleviate confusion, this article focuses on the access version of the Atlas

Jul 1, 2010

By Juan Camus

To understand why some companies excel in creating value, Jim Collins (2001) and a group of postgraduate business students engaged in a comprehensive, five-year research project. They examined 1,435 U.S. companies for more than 40 years, seeking those that made significant improvements in their financial performance over time. The distinctive pattern sought was: ?Fifteen-year cumulative stock returns at or below the general stock market, punctuated by a transition point, then cumulative returns at least three times the market over the next 15 years. ?The search identified 11 outperforming companies, all in different industries, that were called the ?good to great? companies. To contrast these companies with similar peers within the same industry, the search also selected a group of comparison companies that failed to make the leap from good to great. Collins then set out to examine the transition point. What distinguishing features did the good-to-great companies have that their industry counterparts did not? At the heart of the findings about these outstanding companies is what Collins refers to as the ?hedgehog concept? ? how to find the one big thing that the company must focus on. According to Collins, those who built the good-to-great companies were, to one degree or another, hedgehogs. Those who led the comparison companies tended to be foxes, never gaining the clarifying advantage of a hedgehog concept, being instead scattered, diffused and inconsistent. This insight is complemented by Peter Drucker (2004), an influential management guru, who asserts that the first question an effective executive should ask is: ?what needs to be done?? Asking this question and taking it seriously, he asserts, is crucial for managerial success; and that the answer almost always has more than one urgent task, but the effective leader only concentrates on one task. In this last respect, Drucker emphasizes: ?If they [executives] are among the sizeable minority who work best with a change of pace in the working day, they pick two tasks. I have never encountered an executive who is effective while tackling more than two tasks at a time.?

Jan 1, 2011

Editor?s note: Each year, the June issue of Mining Engineering features an industrial minerals review. Several people put in a fair amount of time in developing the material for this issue, all the while doing their own jobs. Thank you to the industrial minerals annual review editor, to the Industrial Minerals and Aggregates Division technical committee chair and vice-chairs, and to the authors of the individual commodity profiles. Jim Norman, member SME, of Tetra Tech, is the industrial minerals annual review editor. Candace Trimble, member SME, of Oil-Dri Corporation of America, is chair of the Industrial Minerals and Aggregates Division?s Technical Committee.

Jan 1, 2012

By M. Sunkpal, K. C. Kocsis

"An underground environment with high air temperature and humidity conditions generated from various heat and moisture sources can significantly affect the thermoregulation processes of the human body. This can lead to a series of heat-related illnesses such as heat exhaustion, heat cramps and heat stroke. The majority of the metabolic energy of a mine worker results in the production of heat. If the human body is to maintain thermal equilibrium, then this metabolic heat must be transferred to the ambient surroundings at the same rate. The heat loss from the human body occurs through a combination of heat transfer processes, such as respiratory heat exchange, convection, radiation and evaporation. If the heat loss from the human body to the ambient surroundings is less than the metabolic heat produced, the excess will be accumulated within the human body, which will result in a rise in the core and skin temperatures. This can ultimately lead to a heat-related illness or a combination of heat-related illnesses. This paper aims to discuss major heat-related issues and provide an overview of various mine ventilation and cooling systems, which can be employed to overcome high levels of heat and humidity in underground mines. In this paper, the effects of heat exposure on the health, safety and productivity of the mine workers are also highlighted. IntroductionMining in the United States remains one of the most hazardous industries, despite significant reductions in fatal injuries over the last century (Coleman and Kerkering, 2007; Saleh and Cummings 2011; Jacklitsch, Musolin and Kim, 2016). Occupational health hazards within the mining industry include hazards that are physical, such as traumatic injury or hearing loss; chemical, such as silica or diesel particulate matter; biological; ergonomic; and psychological (Donoghue, 2004; Saleh and Cummings, 2011). The effects of some of these hazards can be diagnosed immediately, while many, like black-lung and silicosis, will have long-term effects on the health, safety and life quality of mine workers (Donoghue, 2004; National Institute for Occupational Safety and Health, NIOSH, 2000). Among these hazards, exposure to heat and humidity can significantly affect the safety, health and productivity of mine workers, particularly in deep and hot underground mines (Roghanchi, Sunkpal and Kocsis, 2015). Short-term acute heat exposures can cause a rise in the core temperature of the human body, which can result in a heat-related illness or combination of heat-related illnesses. Adverse long-term chronic heat exposure can generate serious occupational heat-related illnesses, such as cardiovascular diseases, mental health problems and chronic kidney diseases. High core body temperatures coupled with dehydration can generate negative behavioral effects such as physical fatigue, irritability, lethargy, impaired judgment, loss of dexterity and loss of concentration (Xiang et al., 2014)"

Jan 9, 2017

By Phil Jones

"Dilution — planned and unplanned – remains a significant cost impairment in the mining process. A series of trials were held over a sixmonth period in fiscal year 2018 (FY18) that established the cost-benefit of new technology as it applies to the alignment accuracy of production drilling rigs in underground mining, thus confirming its ability to limit drilling as one of the causes of dilution. The trials identified three underlying factors affecting drilling accuracy, measurable by blast-hole deviation surveys of planned versus actual toe data. These were rig alignment error, collar location change/ error and in-hole deviation.The trials involved a comparison of existing rig setup processes and technology, with the new technology (Minnovare’s Production Optimizer system). The trials were undertaken in the same environment: the Cracow gold mine, an operating underground mine. The comparison first revealed the extent to which rig alignment impacts blast-hole deviation. Secondly, the new technology was proven to limit rig alignment error, thereby reducing average blast-hole deviation and increasing the number of holes drilled within tolerance by 160 percent.The increased accuracy reduced stope dilution by reducing over-break of subgrade ore. The new technology was implemented at Cracow during the latter half of 2018. Despite utilizing the new technology for just six months of the year, the mine recorded a 5 percent overall reduction in dilution for the full year compared to the previous year (FY17); from 22 percent down to 17 percent (a net decrease of 22.7 percent). Mine management attribute a significant proportion of this reduction to the new technology, along with sequencing and planning improvements. This opinion is backed by detailed stope reconciliation data taken during the trial from 28 stopes — representing 20 percent of the total tonnes mined during FY18. The data identified that stopes drilled using the new technology recorded 62.6 percent less average dilution."

May 1, 2019

By Robert Stefanko

13.1-SUBSIDENCE AND GROUND MOVEMENT ROBERT STEFANKO 13.1.1-SUBSIDENCE AND FAILURE This treatment of subsidence and ground movement will be confined to subsidence control for limiting surface damage by assessing the significant parameters affecting ground movements during mining to optimize mining techniques. The material will be equally applicable to evaporite mining as well as coal but will not deal with block caving or similar systems where failure is deliberately induced and surface protection is not necessary or provided. When an underground opening is established, the original equilibrium is disturbed with resultant stress concentrations. While many factors are involved in opening stability, the span (W) undoubtedly is one of the most important factors in failure. Assuming it is relatively small, the overlying rock strata can bridge across the opening and little if any movement or convergence of top and bottom will occur. However, as the span increases, a point is reached where the stress in the overlying rock strata exceeds some strength value of the rock, and the top breaks. If the opening span is limited to some subcritical value (-We) and/or is at great depth (D), a pseudo-arch will form, achielring stability before rupture occurs to the surface. The boundary of this arch is thought to approximate an ellipse in form with the major axis vertical and equal to four times W, although there has been little field research to substantiate this theory. However, if the width of this opening is increased at this horizon to some critical value (W,) or the same span is created in a shallower seam, the overlying strata ill progressively rupture to the surface and the characteristic subsidence trough is formed (Fig. 13-1) The area of the surface affected is much greater than the area of the seam extracted, depending on the "angle of draw" (a), which is the angle between a vertical line from the edge of the opening and another line extended to a point at which subsidence tails out to zero. This angle has been found to be about 35° in Europe but is rather academic, being a function of instrument precision in detecting subsidence. Since the subsidence effect is so small at any point beyond n 25° angle, this latter may be considered the practical limit of subsidence. Further- more, indications are that the angle of draw varies with depth and nature of the strata.' In a field study over a 1,000-ft-deep potash mine in New Mexico, the maximum angle of draw was found to be 51.5°.2 So far, only a single opening has been considered. However, the width of the excavation applies to any complex mining system of entries, rooms and longwalls as long as the seam has been fully extracted and the width represents the distance from one solid rib to another. It will be noted that the amount of vertical displacement varies from point to point on the surface (s), but the maximum subsidence for a given trough occurs at the center (S). This latter value may not he equal to the maximum possible subsidence (Sm) which occurs only if a critical or super- critical (+W,) width has been exceeded (Fig. 13-1). Substantial surface damage can result when subsidence occurs. Factors affecting the amount and type of ground movement are: thickness and properties of the seam, angle of draw, width of excavation, depth and type of overburden, inclinations of strata and surface, and the amount of support left in the gob. In Europe,

Jan 1, 1973

By S. D. Van Nort

The Grasberg porphyry copper-gold deposit of Freeport Indonesia Inc., an 81% owned subsidiary of Freeport-McMoRan Inc., lies within the Ertsberg Mineral District in central Irian Jaya, Indonesia. The Grasberg deposit was discovered during a drilling campaign initiated in early 1988. Production at the open pit Grasberg deposit commenced in December 1989. The Grasberg copper-gold orebody is contained with a young igneous complex of dioritic composition which intrudes limestones of the Tertiary New Guinea Group. Alteration is typical of porphyry copper deposits worldwide except that higher grade primary chalcopyrite with significant gold values is associated with a centrally located zone of strong quartz stockwork.

Jan 1, 1991

By P. M. Hawley

In April 1975 Kaiser Steel Corporation and the United States' Department of Energy entered into a cost-sharing agreement for the demonstration of shield-type longwall supports on three consecutive longwall panels at Kaiser's York Canyon' Mine in New Mexico. Under this agreement the Department of Energy supplied 117 Hemscheidt 320 HSL caliper-type shield supports and hydraulic pumps for the duration of the demonstration. The purpose of the demonstration was to educate the U.S. coal mining industry as to the benefits in production, productivity, health and safety, and increased coal extraction afforded by shield-type longwall mining systems and to provide the industry with a working model. A detailed description of this demonstration is given in U.S. Department of Energy Publication No. DOE/ET/12530-T1, entitled "Demonstration of Shield-Type Longwall Supports at York Canyon Mine of Kaiser Steel Corporation," hereafter referred to as the York Canyon Report.

Jan 1, 1984

"Mining of ore bodies that are located at great depths enforces long distances to move the excavated rock masses to the surface. The excavated rock mass contains not only ore that can be economically extracted from the face but also waste, which is usually discarded several steps further downstream in the process. As a result, a large amount of rock is transported to the surface, influencing the costs at which the ore is produced. Reducing the amount of waste rock being transported to the surface by introducing a near-to-face sorting plant would improve the in many cases strained transport system in the deep mine. In this study, one of Boliden’s cut-and-fill mines was analysed with respect to the challenges related to rock transportation and increasing mining depth. The study aims to evaluate the potential use of a new near-to-face sorting system in the operating underground mine. Discrete event simulation was used to study and analyse the rock transportation system with and without the near-to-face sorting plant. The paper shows how the underground rock transportation system and the production were influenced when the near-to-face sorting equipment was added into the current system. INTRODUCTION The locations of waste rejection in the mining processes and the cost of removing waste from the system compared with the cost and energy necessary for further comminution are important parts in the material handling system (Bowman and Bearman, 2014). In an underground mine, longer material transportation distances generate the need for further investment in the mobile fleet and ancillary equipment in order to reduce the waste from the material handling as early as possible. One of the ways of reducing the waste (coarse particle size) in material handling is by use of pre-concentration. The benefits of pre-concentration are well known (Schena et al. 1990; Feasby, 1995; Peters et al. 1999; Klein et al. 2002), as well as the factors governing the feasibility of underground pre-concentration (Peters et al., 1999) and the mining integration issues (Klein et al. 2003). In the Onaping Depth orebody in Sudbury, Ontario the study of implementing the pre-concentration resulted in increased capital costs of 6% and a reduction in the operating costs of between 20-40% (Bamber et al, 2004). In this paper, the effects on the production and the transportation system of implementing underground pre-concentration by means of a near-to-face ore sorting plant in the Kristineberg mine are modeled and analyzed using the AutoMod tool. This tool is based on discrete event simulation (DES) (Banks, 2004), allowing high flexibility in customization and enabling the user to view the production of the system before ore sorting plant integration. The sorting plant selected in the simulation is built from modules. The material is fed by conveyor and goes through the comminution, classification, sorting and service processes after which the waste is redirected to backfill headings via trucks. The system mechanically ejects the particles from the feed stream on the basis of the information obtained from both the XRT sensor’s signal and 3D laser scanner based on both density and rate of refraction of light within a particular mineral. The sorting plant could pre-concentrate the metal ore up to 300 mm size. The plant requires little auxiliary infrastructure, is easily modularized for underground installation and can be easily relocated to different areas."

Jan 1, 2016

By Sunil Bodakunta, Sreenivasa Rao Islavath

The abstract highlights the importance of determining the optimum line of extraction in continuous miner workings for improved safety and productivity. The study investigates three extraction techniques (diagonal, straight line along strike, and straight line along dip-rise) using 3D numerical modeling. The dip-rise extraction technique is found to be optimal due to lower stress and displacement, leading to a higher safety factor. The research also develops a continuous miner stability index (CMSI) to predict working face stability based on mining depth and pillar width-to-height ratio.

Apr 28, 2022

By S. K. Singh

To meet increasing demand of coal, underground mining is largely being replaced by the exploitation at deeper horizons and with greater complexities. The exploitation-proposition may be below not-to-be-disturbed surface properties or below water-bodies, posing a constant threat of inundation. Also, the mounting pressures to limit the adverse impacts on the environment bring the extraction-undertaking to face more challenges. An understanding of subsidence-mechanism and a rational quantification of subsidence parameters is a requisite herein. This paper presents such pragmatic quantification, validated at mine-sites in India. In comparison, better productivity, conservation and safety is ensured in this approach.

Jan 1, 1999

By J. F. Colinet, W. R. Reed, J. D. Potts

Dust surveys were conducted at six underground coal mines to determine if deep-cutting practices expose face workers to higher levels of respirable dust. The surveyed mines were able to successfully mine deep cuts without significantly increasing the dust exposures of face workers. In general, all of the selected mines exercised good dust control practices by maintaining water sprays, scrubber airflows, proper curtain setback distances and providing sufficient airflow to the active faces. For exhausting face ventilation, field data indicate that scrubber airflow is the most important factor for controlling dust. Data collected for this study indicate that 20-mesh screens should be cleaned for every 12.2 m (40 ft) of advance, because 22% of the deep cuts surveyed for this study experienced a 20% to 35% decrease in scrubber airflow over the course of the cut. For blowing face ventilation, field data and past research indicate that dust control is aided by maintaining a proper curtain-to-scrubber airflow ratio of 1.0 (measured before scrubber activation), as well as a curtain setback distance that allows the miner operator to stand at the mouth of the curtain for the entire cut. Dust levels on the bolting faces did not appear to be affected by the longer cycles associated with deep-cut mining when good ventilation practices were used.

Jan 1, 2011

By W. D. Bachman

A study has been made of wet, autogenous grinding of disseminated copper ores, including testing of a large number of samples from Kennecott Copper Corporation's Chino mine. The efficiency with which the various samples could be ground was found to vary over an extremely wide range, even among samples taken from different locations within the same ore body. These variations in grindability can be qualitatively correlated with the composition of the rock and the fracturing and alteration that had occurred. Because of the large-scale non-homogeneity of disseminated copper ore bodies, extensive and careful testing of autogenous grinding is needed. An accurate correlation of the grinding data from various samples with the geology of the ore body and with mining plans will indicate if variations in grinding mill throughput can be avoided in practice by mixing or blending of mill feed and if, therefore, autogenous grinding can be applied successfully.

Jan 1, 1970

By John H. Lichtblau

There are three parties to the oil imports controversy: the domestic oil producers, whose side has just been ably summarized by Mr. Jameson; the oil importers; and the public. Domestic producers and importers are both motivated by economic self-interests, that is by their natural and legitimate desire for profit maximization, in their respective positions. Thus, domestic producers, rightly, regard every barrel of imported crude oil (with the exception of some specialty crudes) as a displacement of a barrel of their own crude. Hence, the lower the import Level the better they like it. Conversely, U .S. refiners whose plants are located at the seaboard or at certain inland waterways generally welcome a higher level of imports because refiner profits are based primarily on the spread between the crude oil price and the refined products price, since crude oil represents by far the refiner?s largest cost factor. The relatively low cost of foreign oil means therefore higher profits to those refiners able to process such oil, This applies particularly to integrated companies whose own domestic oil production is insufficient, to meet their refinery requirements but who have developed ample low-cost foreign oil supplies.

Jan 1, 1962

By FELIPE SÁNCHEZ, PHILIPP HARTLIEB

Innovation plays a critical role in the mining industry as a tool to improve the efficiency of its processes, to reduce costs, but also to meet the increasing social and environmental concerns among communities and authorities. Technological progress has also been crucial to allow the exploitation of new deposits in more complex scenarios: lower ore grades, extreme weather conditions, deeper deposits, harder rock mass, and high-stress environments. This paper discusses the importance of innovation for the mining industry and describes the mechanisms by which it is carried out. It includes a review of the drivers and actors involved and current trends. The digital transformation process that the industry is going through is analyzed, along with other relevant trends that are likely to shape the mining of the future. Additionally, a case study is presented to illustrate the technical and economic implications of developing a disruptive innovation project.

Jul 23, 2020

By V. Rajaram

Rock reinforcement systems are used in open pit and underground mines to stabilize the rock mass in-situ and provide safe working conditions. Significant progress has been made to date in the design and implementation of rock reinforcement systems to accommodate bad rock conditions and larger excavations. However, the rationale for the design of rock reinforcement systems remains essentially the same and can be categorized into three groups, namely 1. to create a beam of competent rock in stratified formations, 2. to resist sliding motion in jointed rock, 3. to passively support the superincumbent loads in highly stressed ground. Case histories of the rock reinforcement sys¬tems that illustrate these design approaches will be presented in this paper.

Jan 1, 1983

By John B. Gustavson

This paper describes a case history of geochemical prospecting. An area of known mineralization was available for an orientation survey which led to the selection of elements and criteria for a reconnaissance survey in the area offsetting the known mineralization. Certain anomalies were found which were then made subject of confirmation sampling and of rock geochemical investigations. Inasmuch as the geochemical prospecting technique specifically led to a detailed area which now serves as a target for drilling and other exploration efforts, the geochemical prospecting part of the program is considered successfully concluded and, therefore, reported on here. Whether the target area will turn out to host the deposit or not is, of course, of utmost importance to the Company, but is of less importance to this paper. We will describe the concepts, the planning, the execution, the analysis and the interpretation of this typical geochemical prospecting case. A number of people on the staff of International Oil & Gas, Inc. have participated in this prospect, as have students from Southeast Missouri State University and their professor, Gary M. Lowell. In addition, the Missouri Geological Survey has been most helpful with records and letters on the century-old prospecting and mining in the general area. Many valuable discussions have also been held with geologists from the industry who, from time to time, have visited the area, examined the property and reviewed the status of the project. The support and interest from all these parties has made it possible to pursue and expand this exploration concept from one of being just "more of the same kind" to the most chal-1enging and exciting with which this author has ever been involved, namely the prospect for tin porphyry deposits in the mid-continent United States.

Jan 1, 1977