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By Nathan Bowersox, Zuzana Skovajsova, David M. Jurich, Brian Harris

When unwatered after more than 50 years of operation, the White Rock Tunnel of the Upper American River Project in the foothills of the Sierra Mountains exhibited failing rockbolts and ground falls. Repairs designed for the 5 mile-long, 24-foot horseshoe unlined hydropower tunnel included pattern rock bolts, shotcrete, and cleanout of the rock trap. The work, originally scheduled for two 3-month winter outages, was completed under challenging conditions in a single 4-month outage following a carefully sequenced work plan using robotic shotcrete and rockbolter machines. Flexibility, creative solutions, and collaboration by all parties were key to project success.

Jun 13, 2021

By F. Nelson

RJB Mining is the largest coal producer in the UK. In January 1995 the Company acquired the Central North and Central South Regions of British Coal consisting of: ? 15 operating collieries -including capital equipment ? 2 care and maintenance mines ? 16 operating Opencast sites ? Interest in 26 prospective and 46 potential Opencast sites ? Approximately 417 million tonnes of proven and probable reserves and considerable mineral resource ? 9 million tonnes of coal stocks ? Long term contracts to supply approximately 90 million tonnes of coal to National Power and PowerGen to the period of 3 March 1998 ?Approximately 7,600 employees and 4,500 mining contractual labour. Up to the acquisition RJB Mining had the capacity to produce 14 million tonnes of saleable output with an approximate 1,500 strong workforce.

Jan 1, 1998

By Chee Theng

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

Jan 1, 2015

By Reece Kurre, Gabriel Walton

"Roof bolting has long been used in underground mines across the world to provide ground support. Modern roof bolts are cheap and easy to install with the use of specialized machines as a part of the production cycle. Lhoist North America’s Crab Orchard Mine is an underground room and pillar limestone mine that uses mechanically anchored roof bolts for ground support. The mine currently employs two different roof bolting patterns: a standard 5 × 5 foot pattern, and a 2.5 × 2.5 foot pattern for use in areas with particularly hazardous roof conditions. The purpose of this study is to evaluate the relative effectiveness of each bolting pattern.A series of numerical models were created using RocScience’s RS2. The models were based on a symmetrical section of the mine at its deepest point, and were modeled using Generalized Hoek-Brown failure criterion along with a discrete fracture network. A series of sensitivity analyses were performed on the models by varying parameters such as joint friction angle, crack persistence, joint randomization, and tensile strength of the limestone. Based on the results of the original models and sensitivity analyses, it appears that the standard bolting pattern provides sufficient roof support capacity under almost all the expected conditions at the mine, since factors of safety below the design value of 1.5 were only found for individual bolts in a few of the worst test cases considered. These results can help improve the Mine’s productivity and reduce operating costs without compromising safety.INTRODUCTION AND CASE STUDY DESCRIPTIONLhoist North America’s Crab Orchard Mine is an underground limestone mine located in Crab Orchard, Tennessee. The mine is located under an 800-foot-high mountain, and outcrops on three sides. The mine is accessed through three separate portals and has two main levels, along with a partially developed third level. Extraction is accomplished by the room and pillar method using 50 × 50 feet pillars and 50 × 50 feet rooms. The mining height is limited to 50 feet to keep the pillar width to height ratio around 1.0. Each heading is excavated in a two-stage process that consists of a 30-foot-tall top heading and a 20-foot-tall bench. A distance of at least 30 feet is maintained between the two levels at all times (Crab Orchard Mine Technical Staff, 2017)."

Jan 1, 2019

By V. Kecojevic

The objective of this research was to establish the relationship between production, consumption and energy cost in the surface mining of bituminous coal. Specific energy sources such as diesel, gasoline, electricity, explosives and bituminous coal were considered in this study. Gain in net energy, proportion of the cost of energy consumption and total energy cost relative to total revenue of extracted coal were determined, and a new energy efficiency index and a new energy-cost ratio were established. A case study on an operating surface coal mine was carried out to demonstrate the application of the newly developed method. The results of this study can be used by the mine operators in establishing strategies for the optimization of energy production and consumption, and for reducing the cost of bituminous coal extraction.

Jan 1, 2014

By J. Mark Richardson

The use of an integrated software package to simulate and optimize the performance of mineral processing circuits is illustrated by three examples. Each represents application of the software and associated techniques to optimization of an existing plant. In the first example, a South-western U. S. copper company employs the method to simulate and improve performance in crushing, screening and SAG milling. A second copper producer evaluates equipment changes and flowsheet alternatives in a closed-circuit ball mill-cyclone operation. A Southeastern U. S. aluminum refinery optimizes performance of a dry milling and classification circuit for production of carbon particles used in anode casting. Graphical and tabular data describe the circuits simulated and the results achieved in each example.

Jan 1, 1990

By Rick Frechette, Greg Nelson

"The 2018 Elko Roundtable was held at the Red Lion in Elko, NV on March 15, 2018. The gracious host was once again Knight Piésold. Attendance was robust with representatives from more than 14 mining properties across Nevada representing nine corporations. Total attendance was at its highest in almost a decade. A high level of interest was also gauged by the number of companies with multiple attendees.The topic of water in mining was clearly a factor in creating the large show of interest. In terms of industry trends that are tracked annually, this topic had been absent from the list for more than 10 years (Deloitte, 2018) but was squarely planted there this year. And deservedly so. Three attending companies are signatories of the International Council on Mining and Metals (ICMM) which espouses a firm stance on water stewardship (ICMM, 2017).How’s the water?It is reported that water scarcity affects more than 40 percent of the world’s population (Deloitte, 2018). Consumption of water in the United States, based on the last detailed census, entails only 1.5 percent usage by the mining industry. The largest users are reportedly thermoelectric power and irrigation, combining for more than 75 percent of the U.S. consumption. During the prior census period, water usage at mines was up dramatically (USGS, 2014).Mine water source usage is primarily a mix of ground water and saline or fresh surface water resources. Over the previous period, saline sources experienced the greatest percentage in growth as a mine water source, nearly doubling in use. Nevada ranks second as a state nationally in mine water consumption. California is the leader, and Nevada is immediately followed by Utah and Alaska (USGS, 2014).Water rights in Nevada and the ongoing litigation at the state level, particularly over the Humboldt River basin, have elevated the concern over the supply of water and have raised the interest regarding the topic of water across the mining industry as well as within other industries.The Elko Roundtable meeting began with a safety share and introductions, and included each attendee mentioned a water problem or solution that he or she would like to discuss during the day. An interesting list of subtopics was developed from this round robin and yielded the following most common themes:• Mine pit dewatering during operation and pit wall stability.• Draindown from tailings dams and heap leach pads and dealing with this at closure.• Post closure pit lakes, pit lake water quality and associated water rights."

Dec 1, 2018

By A. Bieg, M. Samson, Z. Bell, A. Zinsser, J. Schuyler

As the world progresses toward the renewable energy transition, the demand for minerals increases exponentially. According to the International Energy Agency (IEA) 2021 Net Zero by 2050 Report, critical mineral production needs to grow six times to combat climate change. It’s estimated that four to seven percent of global greenhouse gas (GHG) emissions come from the mining sector’s Scope 1 and 2 (direct and indirect) emissions. Including Scope 3 (upstream, downstream, and embedded) emissions, the sector accounts for 28% of global GHG emissions. In a typical mining operation, diesel fuel is the biggest source of direct GHG emissions, and haulage is often the main source of diesel emissions. Large haul trucks have been the industry standard for over 50 years and offer flexibility, relatively low capital cost (especially with equipment lease options), and guaranteed technology with known maintenance. The challenge will be to justify their continued use when there are more economical options that lead to significant reductions in GHG emissions. The purpose of this study is to compare five haulage options in terms of GHG emissions, using the methodology defined by the Greenhouse Gas Protocol Scopes 1, 2, and 3 (Category 2). Additionally, this analysis compares operating and capital costs associated with the five haulage options (emerging and proven technologies): 1) Diesel-Electric Haul Trucks, 2) Battery-Electric Haul Trucks, 3) Fuel Cell Haul Trucks, 4) Railveyor, and 5) Conveyor. This analysis looks at the emissions and costs associated with operating the equipment (fuel and electricity), the embedded emissions and costs associated with the construction and installation of the equipment itself, and the associated infrastructure (roads, powerlines, and rail).

Feb 1, 2023

By S. J. Jung

Determining the correct combination of mix components and water for high-density paste backfills with the transport and deposition properties necessary in a mining operation is a difficult task. Rheologic properties cannot be determined without conducting full-scale pumping tests, and data from existing tests are very limited. The following presents the findings of investigations undertaken to determine if paste backfill rheology can be determined using existing techniques and which mix and system variables have the greatest influence on transport pressure loss. Data from lab-oratory-scale pumping tests were used to produce a rheologic model of flow behavior for comparison, and a statistical analysis was conducted to determine the most significant factors affecting transport pressure loss.

Jan 1, 1994

By David B. Brooks, Roger L. Williams

Control of the environment is as old as mining. Engineers have always had to consider how best to deal with the surface, and the character of the surface environment always affects mining method in some way. However, if the relationship of the mine to the environment is old, today's approach is new. For one thing, land, air and water formerly could be viewed simply as obstacles to be overcome or resources to be utilized to win ore at the lowest possible cost. Now we have come to realize that these nonmineral components of the environment also are highly valuable. For another thing, environ- mental protection has become a public policy issue. Again, a special public interest in land and land use is old. From the firs(, the crown claimed extra rights in valuable minerals, and to this day a multitude of laws and regulations control-and tax-land use in every country. What is new is the detailed public attention bring given to waste management practices, whether these wastes be in the form of solids, liquids or gases, and regardless of where in the environment they appear. (It is convenient to lump all mining environmental problems, including hank fires and subsidence, together under the term "waste management," for in effect that is what they are.) As a result of these changes, the mining engineer must consider that lie is dealing with two productive resources the minerals and the remainder of the environment-and he must expect that lie will be judged not only on his efficiency in recovering the one but also on his effectiveness in protecting the other. Further, in seeking to protect the environment, the modern mining-environmental engineer has a dual role. First, there is the obvious task of finding better ways for industry to cope with waste-management problems in actual operations. Second, there is the less obvious but equally important task of helping formulate appropriate public policy objectives for the environment. Throughout; the section it is assumed that mining is an acceptable land use for the tracts under consideration. The question of whether mining will be permitted at all on these tracts is a further public-policy issue, ultimately to be resolved politically and thus, since it is beyond the scope of engineering, is not a subject that can be usefully discussed in a mining handbook. Finally, none of the statements in the section are predicated on the assumption that required waste-management measures will be privately profitable in the conventional sense. Indeed, the reverse is more likely to be the case-at least if accounts are kept so as to include all appreciable costs and a normal rate of return on investment in waste-disposal and reclamation equipment.',',' However, it is clear that improved waste management will be required of mining firms and that, to a considerable although undetermined degree, this expenditure is in the best long-run interest of both public and industry. The several studies that have attempted to quantify the impact of mining on the environment are admittedly rough but still provide enough information to indicate that there is a big job to be done. For example, something approaching 7,000 mi of stream in Appalachia alone are continuously or significantly affected

Jan 1, 1973

By James C. Hower, B. K. Parekh

Introduction The purpose of coal preparation is to improve the quality of coal to make it suitable for a specific purpose by (1) cleaning to remove inorganic impurities; (2) sizing-crushing or screening, or both; and (3) special treatment, such as dedusting. The properties and quantities of impurities in coal are of major importance in the design and operation of steam generating equipment. Although boilers are often designed and equipped to use a wide range of coals, no boiler will perform equally well with all types of coals. All coals have certain properties that place limitations on their most advantageous use. These limitations are especially stringent for many of the older installations. Because of a general lowering of quality of raw coal in recent years, the need for coal cleaning has significantly increased. Among the factors contributing to the need for increased coal preparation are (1) increased demand for quality brought on by market and environmental requirements; (2) increased extraneous dilution caused by mine, health, and safety laws; and (3) depletion of the higher-quality coal seams. The major characteristics of coal and impurities from the standpoint of mechanical cleaning are particle size composition, generally called size consist; density differences; the relative friability of the coal and its associated impurities; hardness; and strength. Some of the other factors related to preparation are petrographic composition and rank. RANK CLASSIFICATION Coal is a general designation for a great number of solid organic minerals with different compositions and properties; all are rather rich in carbon and have a dark color, generally black. Next to mineral oil and kerogen, coal is the most important reservoir of carbon in the world. Carbon is an indispensable necessity of life as well as the main source of energy. Coals are found in stratified deposits, sometimes at great depths. All coals owe their origins to slow decomposition and chemical conversion of immense masses of organic material. As found in seams, coal is a heterogeneous mixture of organic and inorganic materials. Not only are there large differences in the properties of coal originating from different seams, but also in coal removed from different locations in a single seam. A genetic relationship exists between peats, brown coals, lignites, biturninous coals, and anthracites. As a whole, the process of coal formation, or coalification, proceeds as a continuous transformation of plant material, each phase characterized by a degree of coalification, or rank. As a measure of this rank, the carbon content or some related parameter can be used.

Jan 1, 1991

By S. K. Bhatt

This paper reviews major developments in continuous haulage technology for underground coal mines. Haulage systems in use and development are investigated through a comprehensive literature search and visits to mines and manufacturers. The systems include flexible conveyor train, mobile conveyor, multiple- unit continuous haulage, extensible and belt turning systems. Strengths and weaknesses of the systems are assessed in light of their operating under remote control and their application to the computer-assisted continuous mining machine being developed by the US Bureau of Mines. Through mining scenarios, candidate haulage systems are conceptualized to be consistent with the capabilities of the mining machine.

Jan 1, 1991

By E. DeLilia

For the past 30 years, surface mines have moved toward more highly mechanized, automatic systems that continuously mine overburden and ore to in-crease productivity, lower operating costs and minimize manpower needs. To achieve these goals, mine operators must be involved in every step of the machine procurement process. Several factors are involved in making the machines operate economically and efficiently: ? Prudent engineering. ? Proper planning. ? Realistic feasibility studies. ? Effective specification. ? Thorough training of the mine personnel.

Jan 1, 1995

By G. H. K. Pearse

Long range transport of pollutants, particularly of sulphur dioxide and the associated acidic precipitation, has received much attention in the press and in international discussion during the last few years. Studies revealing increasing acidity of lakes and the dying out of fish populations over broad regions of the eastern half of North America have created alarm. In this paper, I will not attempt a description of the acid rain phenomenon. For this r recommend the balanced treatment of the subject by Gene Likens et al (1979) in Scientific Americana For my purposes I accept that the problem is serious and direct my attention to exploring a solution. Ultimately, the key lies in the answer to the question; "What do we do with the enormous tonnages of pollution abatement byproducts, chiefly sulphur compounds, that would arise from pollution control?"' Little thought has been given to this most limiting factor to environmental clean-up. This is symptomatic of a basic flaw in the [philosphy] that under-ins environmental policy. Although this paper is to propose a solution to the abatement byproduct problem, the basic flaw - the firmly entrenched, universally adopted, 'polluter pays [philosphy] as it is currently [understood] - needs some comment.

Jan 1, 1981

By Isabel F. Barton, MarkD. Barton, Christian A. Rathkopf

Molybdenite is the world’s principal source of rhenium (Re), a critical element in multiple high-tech applications. However, the Re contents in molybdenite vary by orders of magnitude on scales ranging from single grains to whole deposits. In order to better understand the systematics of this variation and what geochemical factors control molybdenite Re concentration, and hence overall Re resources, we examine global patterns in molybdenite Re contents through a compilation of > 3000 measurements of Re in molybdenite from > 700 mainly ore-bearing moderate- to high-temperature hydrothermal systems of different types. Our results are similar to but expand on those of earlier studies. Rhenium concentration in molybdenite has a lognormal distribution and varies systematically with type of geologic system, intrusive lithology, and Mo grade. The lowest-Re molybdenite occurs in greisens (geometric mean 1 ppm ± a multiplicative standard deviation of 9), quartz vein-hosted W-Sn deposits (2 ± 5 ppm), unmineralized granites and granodiorites (12 ± 8 ppm), intrusion-related deposits (24 ± 8 ppm), and porphyry W-Sn deposits (16 ± 11 ppm). Rhenium is most enriched in molybdenites from volcanic sublimates (23,800 ± 5 ppm), with skarn Fe and Au (560 ± 5 ppm and 540 ± 3 ppm respectively) and porphyry Cu and Cu-Au deposits next (470 ± 4 and 430 ± 7 ppm respectively). Among porphyries, skarns, and quartz vein-hosted deposits, Re is most highly concentrated in molybdenites from Cu and Au systems and its concentration decreases systematically through Cu-Mo, Mo, Sn, and W deposits. In nearly all cases, molybdenites from systems associated with intermediate igneous rocks contain more Re than molybdenites from systems of the same type with more felsic rock associations. The disparity between Re contents of molybdenite in felsic and intermediate systems is largest for porphyries, quartz vein-hosted, and skarn deposits and is near zero for subeconomic or barren granite and granodiorite Mo systems; felsic intrusion-related deposits have slightly higher molybdenite Re than their equivalents associated with intermediate intrusions. In most systems, molybdenite Re content does not correlate with metal grade, but may have an inverse correlation with Au grade in intrusion-related deposits (based on a small number of data points) and does exhibit a strong inverse correlation with deposit Mo grade. Dilution of Re through larger amounts (higher deposit grades) of molybdenite explains about 40% of this correlation, but the relative enrichment of Re in molybdenite from low-Mo deposits must also reflect some selective enrichment of Re/Mo in porphyry Cu systems compared to porphyry Mo systems. We found no evidence for secular increase or other systematic temporal variation in molybdenite Re content. The data regarding the use of molybdenite Re content as a proxy for mantle influence are ambiguous. Nearly all observed empirical correlations can be traced back to differences in redox state and sulfide concentration, the two geochemical factors identified here and by previous experimental work as the controlling influences on Re mobility under hydrothermal conditions. Hydrothermal systems with reducing conditions (W- and Sn-rich) tend to have low molybdenite Re even though compiled whole-rock data indicate that their source rocks have as much or more Re as those of more oxidized systems (e.g., Cu-rich). Vapor-phase exsolution, crustal assimilation, and mixing with external fluids may all enrich molybdenite Re concentrations in individual deposits and deposit types, but their extent and importance in overall hydrothermal concentration of Re is uncertain. Thus, it appears that the available molybdenite Re resource in an ore deposit largely depends on how the deposit’s redox and sulfidation conditions have varied over time and space during the timespan of hydrothermal activity. Oxidized, high-sulfide conditions tend to concentrate Re in molybdenite, whereas reducing conditions tend to leave Re dispersed at low concentrations in the bulk rock.

By T. McWaters

Miami Copper Company began a block-caving operation in 1911 using a gravity mill to separate copper minerals from the Pinal Schist host rock. The tailing was deposited by the upstream method using perimeter launders and spigot valves in six canyons adjacent to the mill until 1932. In 1928 the larger and more distant Solitude tailing pile was developed which by 1932 was receiving all tailing except for upsets. In 1925 Miami Copper converted its gravity mill to flotation which began to produce higher sulfide copper recoveries.

Jan 1, 1990

By Donald W. Gentry

This paper presents some of the results of a rock mechanics in¬strumentation program designed for, and implemented at, longwall panel 4N at the York Canyon Mine near Raton, New Mexico. The objective of this particular instrumentation program was to determine the response of the rock mass to longwall mining of a thick coal seam utilizing shield-type supports. Measurements were made in the rock along the ground surface, above the coal seam, in the coal seam and immediately below the coal seam. Longwall test panel 411 had a total developed length of 762 m (2500 ft) and a face width of 168 m (550 ft). The seam mining height in the panel area was approximately 3 m (10 ft). The average depth of overburden above the panel is 107 m (350 ft) al¬though it ranges from 73-134 m (240 - 440 ft). Roof support at the face was provided by Hemscheidt shields. These shield-type supports weigh 11.4 metric tons each.

Jan 1, 1977

By T. P. Meloy

A methodology is presented for the spreadsheet solution of processing networks performing separations with the methodology developed here a spreadsheet grid is used to represent networks with and without recycle loops. In this manner, network solutions are numerically approximated by spreadsheet grid solutions. The methodology was used to explore the ramification networks developed by the Chinese for tungsten and molybdenum processing. Non-linear stage transfer functions for two-component sharp separations can be used.

Jan 1, 1994

By SANDEEP KUMAR JENA

This review work reports the recovery of potassiumfromdifferent rocks and mineral sources. The global demand for potassiumis rising consistently due to the growth of agricultural production. A major portion of the world potassium production is consumed in making of fertiliser; however, other uses include those in pharmaceutical, glass, ceramic, food and detergent industries. The availability of soluble potash minerals (sylvite, kainite and carnallite) in different countries like Canada, USA, Israel and Russia makes them as major potash producers, whereas agricultural-based countries like Liberia, Somalia, Central African Republic, Thailand, Indonesia and Malaysia including India meet their potassium requirement through import only. On the contrary, the availability of huge potassium-bearing rocks/minerals (like nepheline syenite, feldspar, mica, glauconitic sandstone) in these countries containing around 4–17% K2O would be a prospective for commercial production of potassium. The potassium recovery from minerals/rocks is very complicated due to the uniform distribution of potassium throughout the crystal structure. Different physico-chemical separation methods like bioleaching, chemical leaching, flotation and roast leaching have been discussed for the successful recovery of potash values from these rocks/minerals. However, the recovery of potassium from hugely available seawater using the chemical precipitation, solvent extraction,membrane separation and ionic exchangemethods is not cost-effective due to the low concentration of potassium.

Aug 31, 2020

By James K. Wright

This chapter will discuss the use of financial models as an evaluation tool for various phases of decision making from exploration strategy to the analysis of a producing mine. The text of this chapter was not received in time for printing.

Jan 1, 1979