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By Y. David

In 1990, the United States became only the second country (after China) to produce more than 900 Mt (1 billion st) of coal in a single year. US production of bituminous and subbituminous coal, lignite and anthracite totaled 933.5 Mt (1.029 billion st) in 1990, 5% more than in 1989. The production gains were largely due to the rebuilding of depleted coal stockpiles by electric utilities and a surge in US coal exports. Domestic coal consumption essentially remained at its 1989 level. A slight increase in electric utility coal consumption was partly offset by a decline in metallurgical coal use. The use of coal in other industries and in the residential-commercial sector remained virtually flat.

Jan 1, 1991

Canada is a major producer of chrysotile asbestos. In fact, Canada accounts for approximately one third of the world chrysotile asbestos production. Deposits are mined and the fiber processed in Québec, in British Columbia on the West Coast and in Newfoundland in the Atlantic region. Foremost among the Canadian provinces is obviously Québec. Some 85% of Canadian deliveries come from mines located in the Eastern Townships, a region which lies along the southshore of the St. Lawrence River, between Montreal and Québec City. At the heart of this vast territory, five (5) mining towns make up what is called the Québec asbestos region. Total capacity of the five (5) mining producers of Québec is about 1 366 000 tonnes.

Jan 1, 1981

By Edward C. Spalding

The mineral estate of Arizona's State Trust lands, which are administered by the State Land Department for the benefit of the common schools and 14 other beneficiaries, totals more than 10.5 million acres, or almost 15 percent of the State's entire area. Trust lands exist in all 15 of the State's counties, with the most and least acreage found in Yavapai and Gila Counties, respectively. Revenues derived from the Trust mineral estate include royalties, rentals, and fees. In Fiscal Year 1983-84, these revenues amounted to $4.2 million, or 13.5 percent of all income received by the Trust during this period. Industrial minerals, led by sand and gravel, contributed $1.1 million from 82 active properties.

Jan 1, 1987

By Dru Brown

More than 150 Mt (165 million st) of material crashed down at the Bingham Canyon Mine (Rio Tinto/Kennecott Utah Copper) near Salt Lake City, UT on April 10, 2013. The mine, one of the largest openpit mines in the world, ceased operations and evacuated personnel prior to the slide when it was discovered that material was moving at a rate of 5 cm/d (2 in./day). The slide destroyed the mine?s visitor?s center, buried several pieces of large mining equipment and severely hampered production. The Kennecott Utah Copper Corp. immediately began to assess the damage and look for options to reestablish operations. The highly unstable ground ? emphasized by another minor slide in September 2013 ? makes any cleanup efforts extremely dangerous. With terrain too dangerous for human operators, Kennecott was forced to look for alternatives that would help the company work on the treacherous slopes of the landslide while also keeping personnel safe.

Jan 1, 2014

By W. B. Lambert

A common decision in openpit mining is to determine the extraction sequence of notional three-dimensional production blocks so as to maximize the net present value of the extracted orebody, while adhering to precedence and operational resource constraints. This openpit block sequencing (OPBS) problem is commonly formulated as an integer program, with binary variables representing if and when each block is extracted. In practical applications, the number of blocks can be large and the time horizon can be long; therefore, instances of this problem can be difficult to solve using the exact approach of optimization. The problem is even more challenging to solve when it includes explicit minimum operational resource constraints. Our maximum value feasible pit (MVFP) algorithm generates an initial integer feasible solution for OPBS problems, in which minimum operational resource constraints are strictly enforced. As an exact approach, we present a Tailored Lagrangian Relaxation (TLR), in which the selection of constraints to dualize is guided by information provided by the MVFP algorithm. We present results and graphics to demonstrate the utility of our techniques for instances containing up to 25,000 blocks and 10 time periods.

Jan 1, 2013

By J. F. Brune

This paper analyzes the explosion hazard resulting from the formation of methane-air mixtures in the mined-out gobs of underground longwall coal mines. Although direct examinations of the gob atmosphere are difficult due to the inaccessibility of these gobs, evidence from methane drainage practices and investigations of numerous mine explosions suggests that explosive methane zones can form within longwall gobs. Explosions and fires resulting from these methane accumulations have led to severe and fatal injuries to the miners. Most recently, this was demonstrated in the explosion of the Upper Big Branch Mine in West Virginia, where 29 miners lost their lives.The paper also reviews current research on numerical modeling of gas flows in longwall gobs and outlines how targeted injection of nitrogen into gobs can effectively reduce the volume of such explosive methane zones. The paper concludes that comprehensive monitoring of gas compositions, along the accessible fringes of the gobs along with inertization, improved ventilation schemes and further research are necessary to control this explosion hazard and make mining operations safe.

Jan 1, 2013

By J. W. Francis

The paper about to be presented deals with the relatively straightforward problem of mining two seams of coal separated by an interval. This may seem to be a simple problem but within a twenty-mile radius of Consolidation Coal Company's Burning Star # 4 Mine at least seven (7) different techniques of two-seam mining have either been tried or are now in use. This great variety of techniques should point out that there is no single simple solution; a conclusion often reached when dealing with mining problems. As a background for the techniques presently in use at the Burning Star # 4 Mine, we will briefly outline the other five (5) stripping techniques used in the area: 1. Captain Hine 6360 Range Diagram (Figure 1) 2. Leahy Mine Range Diagram (Figure 2) 3. Burning Star # 3 Mine 5860 Range Diagram (Figure 3) 4. Burning Star # 3 and # 4 Mines Dragline in Pit Range Diagram (Figure 4) 5. Captain Hine 2570/5561 Range Diagram (Figure 5) Each of these techniques was chosen because it provided the best and least expensive alternative for mining the coal under the particular restraints encountered. The Mine Engineers at our Burning Star # 4 Mine, Mr. Dennis Mahan and Mr. William Weaver, will now detail two additional mining techniques, out-lining our experience to date.

Jan 1, 1977

By A. Cecala, J. Noll, J. Hummer

The National Institute for Occupational Safety and Health has observed that many control rooms and operator compartments in the U.S. mining industry do not have filtration systems capable of maintaining low dust concentrations in these areas. In this study at a mineral processing plant, to reduce respirable dust concentrations in a control room that had no cleaning system for intake air, a filtration and pressurization system originally designed for enclosed cabs was modified and installed. This system was composed of two filtering units: one to filter outside air and one to filter and recirculate the air inside the control room. Eighty-seven percent of submicrometer particles were reduced by the system under static conditions. This means that greater than 87 percent of respirable dust particles should be reduced as the particle-size distribution of respirable dust particles is greater than that of submicrometer particles, and filtration systems usually are more efficient in capturing the larger particles. A positive pressure near 0.02 inches of water gauge was produced, which is an important component of an effective system and minimizes the entry of particles, such as dust, into the room. The intake airflow was around 118 cfm, greater than the airflow suggested by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) for acceptable indoor air quality. After one year, the loading of the filter caused the airflow to decrease to 80 cfm, which still produces acceptable indoor air quality. Due to the loading of the filters, the reduction efficiency for submicrometer particles under static conditions increased to 94 percent from 87 percent.

Jan 1, 2015

This study was conducted to evaluate the effects of a diesel particulate filter (DPF) regeneration process on the concentrations and size distributions of aerosols in an underground mine. Two active regeneration strategies were examined for an electrically regenerated sintered metal fiber filtration system, and the effects were compared with those observed for a muffler and the same system operated in a passive configuration. The effects were assessed for three steady-state engine operating conditions. The number and mass concentrations and size distributions of aerosols in mine air were found to be strongly affected by the exhaust configuration, engine operating conditions and the regeneration process. When the system was operated in active configurations, the concentrations exhibited a transient and cyclic nature. At light load conditions, the distributions of aerosols in mine air were dominated by accumulation mode aerosols for all exhaust configurations and regeneration strategies. High concentrations of nucleation aerosols were observed when the DPF system was used and the engine was operated at high load conditions. A positive correlation between accumulation of particulate matter in the filter and the efficiency of the filter in removing accumulation mode aerosols was observed for all conditions. In the case of high engine load, reductions in accumulation mode aerosol concentrations were linked to a substantial increase in number concentrations of nucleation mode aerosol. Overall, the filtration system was found to be very effective in reducing total aerosol mass and elemental carbon concentrations for all engine operating conditions. However, the system was substantially more effective in passive than in active regeneration configurations.

Jan 1, 2012

By ANDREW HOBERT, Maoming Fan

Low-cost and environmentally friendly green froth flotation modifiers of plant origin, such as guar gum, carboxymethyl cellulose (CMC) and starch, have been used in the flotation of some sulfide and nonsulfide minerals. This paper discusses the fundamentals, current applications and potential new applications of guar gum, CMC and starch in minerals flotation. In this study, improved flotation performance was achieved using some green modifiers in flotation columns.

By AMAN SONI, JONATHAN G. BAGGETT, Nino Ripepi, JUAN J. MONSALVE, Richard Bishop

Underground stone mines are vulnerable to karst void formations due to the erosion of carbonate rocks by groundwater flow. The voids or cavities may lead to hazards including ground collapse and sudden outflow of clay-rock sediments during the development of the mine. This study evaluates the effect of karst voids on the strength of pillars in an underground room-and-pillar limestone mine. Ground-penetrating radar (GPR) surveys were interpreted to map the void boundaries inside a karst-affected pillar. A combination of LiDAR scanning and virtual discontinuity mapping is used to formulate the discrete fracture network (DFN). Discrete element modeling (DEM) helps simulate the effect of karsts and discontinuities in the pillar models with varying stress. It is observed that the cavities may lead to a significant reduction in pillar strength. Apart from posing a hazard to miners and machinery, any advance into these cavities may disrupt mine operations. This research serves as an initial step toward understanding the importance of pillar design in underground stone mines affected by karst voids to prevent local instability or pillar failures.

Sep 1, 2022

In the grand scheme of things, the 9.5-t (21,000-lb) shipment of molybdenum concentrate that left Freeport-McMoRan?s Climax Mine site on May 10, 2012 was not unlike the thousands of others that have been hauled away from the site during the last century, except for the fact that this shipment marked the official rebirth of one of America?s greatest mines. For nearly two decades, 17 years to be exact, there was no production from the mine that was once the largest underground mine in the world and was so important to the Allies? effort during World War II that it was assigned the highest priority of any mine in the United States by the War Production Board. The economic recession in 1980 put an end to the mine?s success, and the Great Recession of 2008 nearly derailed the mine again. But, like the nearby town of Leadville, CO, the mine survived thanks to an investment of more than $700 million by Climax Molybdenum Co., a Freeport-McMoRan company, to bring the Climax Mine back into production.

Jan 1, 2012

By Yao Dun-Pu

Solution mining, sometimes also refered to as chemical mining or bacterial mining, is an innovative technology which, by making use of proper chemical reagents and taking advantage of bio-chemical action of some micro-organism species, can dissolve effectively most. desirable metallic values from ores and then extract them profitably from the resultant metal-bearing solution by suitable means to form the metal product it is more preferable to the conventional mining methods, not only because of its capability to improve working conditions and minimize environmental problems either underground or on surface, but also for its amenability in particular, to exploit low-grade or submarginal ore bodies, or those deposits which are too deep-seated to be mined out economically. Furthermore, it also provides a potential approach to win metals directly from their ores or ore-deposits in-situ by more simplified methods and at a lower cast than the conventional mining-milling-smelting process would do previously. Hence, in developing countries such as China, it will most, probably become a new mining tool of great promise. (1)

Jan 1, 1981

By J. Chai, Q. Yuan, B. Qiu

"Overburden strata deformation monitoring is one of the key problems in ground control. Using geophysical method through surface drilling to detect strata deformation is commonly used in the industry. In this paper, a geophysical method based on the distributed optical fiber sensing (DOFS) system were conducted in the laboratory, where a DOFS-based strata deformation monitoring experiment was performed with three physical models. The results show that the DOFS method precisely detects the rock mass deformation and strata structure forming with the Brillouin frequency shifts (BFS) representation. The BFS curves are divided into three phases, which reflects the horizontal three zones developed in the overburden. The BFS distribution presents a multiple stages form, the 1st stage corresponds to the caving zone and the 2nd stage corresponds to the fracture zone. Based on the multiple stages form, the evolution of the water flowing through fractured zone have been determined and the controlling effect of key strata over the water flowing fracture has been pointed out. In the end, the comparison validation proves the accuracy and reliability of this method, and it could be a new approach for the ground control research. INTRODUCTION Overburden rock strata above the work face space will propagate from slight deformation, part destruction to violent movement because of the underground coal mining. It is fundamental and an intrinsic requirement of ground control to monitor the mining-induced rock mass deformation.[1] Overburden strata have their significant mechanical behaviors and movement under damage deformation and fracture. Overburden strata deformation affect the mining ground pressure control directly, and performance in the relationship of supporting equipment and the surrounding rock, the mining-induced fracture distribution and the loss of underground water resource, the ground surface structure stability and the ecological environment.[2] From the perspective of the concept of safe and efficient scientific coal mining: the overburden strata deformation is an important part of mining method selection and reasonable supporting solutions decision which can solve the issues like the roof supporting force calculation, overburden fracture distribution and gas drainage, ground subsidence, separation of coal and rock control and top-coal recovery rate and so on. From the perspective of green and ecological mining: the overburden strata deformation is the key basis of studying the mining-induced ground subsidence and mining area ecological damage, and such engineering problem like environmental protection in mining area, ecological restoration in mining subsided land and the water conservation in fragile ecology area of mining could be solved based on it.[3-6] Therefore, the mining-induced overburden strata deformation is the key of ground control and needs to be controlled artificially."

Jan 1, 2017

By Bill Kendall

"In coal mines, handheld air, electric and hydraulic powered drills are used along belt conveyors, in single entry development, in entries where there are obstructions, and in longwall recovering bolting. In hard rock mines, pneumatically powered jackleg drills are typically used in narrow vein mining. Drilling and bolting in narrow confines has traditionally been performed with pneumatically or hydraulically powered hand-held drills or newer electrically powered hand- held hammer drills due to their low cost, simplicity of operation, and extreme flexibility due to their small size. Mechanized equipment has typically been too large, too expensive, inefficient due to the confined space, and too restrictive due to lack of flexibility for use in narrow confines.Although the handheld equipment is effective, it requires operator exposure to certain inherent hazardous conditions in use. These include falling rock from the roof, rib and face; tripping hazards; bending twisting lifting hazards; high noise levels and chemical fumes from the pneumatic exhaust. The operation of the hand held equipment can adversely affect the long-term health of the operator - continual jackleg operation frequently results in longterm damage to hearing, shoulders, arms and wrist joints and back injuries. This results in a reduction in life style for the operator and higher personnel turnover rates for the mining company.Hand-held drills also typically have limited thrust and torque capability that limits their ability to push long resin bolts, inadequate torque to properly install resin bolts or to properly torque mechanical or tensioned rebar bolts. Hand-held drills do not offer any type of protection for the operator from roof or rib falls. They do not offer any means for handling roof or rib mesh. Since the operator stands on the ground the maximum safe drilling height without use of a ladder or "riding the drill" is limited to 2.44 m (8 ft)."

Jan 1, 2014

By U. Thorley

This paper presents an overview of surface mining activity in the Canadian oil sands and how the mine operators interact with the province of Alberta's Mine Financial Security Program (MFSP), which took effect April 1, 2011. The MFSP approach to reclamation assurance results in the government of Alberta sharing a portion of reclamation liability through the majority of an oil sand mine's life. In order to determine the potential fiscal magnitude of this shared liability, an examination of the expected costs of oil sands reclamation activities through a study of corporate asset retirement obligation (ARO) liabilities and other corporate disclosures is presented. The province of Alberta's Environmental Protection Security Fund (EPSF), which formerly secured oil sands mine reclamation activities is discussed. Reclamation costs in the oil sands are poorly understood. The MFSP provides what it characterizes as a conservative estimate of C$75,000/ha, while corporate disclosures by Canadian Oil Sands Ltd. place expected costs at C$180,000/ha. There is significant risk associated with the apparent uncertainty surrounding reclamation costs.

Jan 1, 2012

By H. M. Park

Risk is a major factor in all mining activities, arising from many internal and external variables. The authors? research has resulted in a systematic method for the quantification of risk in mining projects (Park, 2012). This is the second part of a three-part series. The first part was published in the October 2013 issue of Minining Engineering magazine and can be found here at www.me.smenet.org. This paper discusses methods of assessing the overall risk associated with those variables, and presents a statistical model based on a survey of 31 experts. The third paper, to be publised at www.me.smenet.org on Oct. 14, presents an evaluation of the statistical model, using data from previous mining investment decisions in which the authors have been involved.

Oct 1, 2013

By Ajit Godbole, Ping Chang, Ramakrishna Morla, Purushotham Tukkaraja, Shivakumar Karekal

This paper presents the results of a study on the optimum auxiliary fan location to control air recirculation in dead-end workings where diesel-powered vehicles operate. Investigations were conducted with various secondary fan locations from the dead-end crosscut and with the intake air quantities varied using different auxiliary fans to control air recirculation and diesel particulate matter (DPM).

Jul 1, 2023

By D. Lauriski

The recent spate of catastrophic events at U.S. mines raises the question as to whether or not the mine safety and health system in the U.S. is broken. The prescriptive regulatory regime in the U.S. is not a cure-all for a broken system. Without totally dismissing the contribution of a prescriptive regulatory approach, this paper argues that safety in the U.S. mining industry would be enhanced if the nation adopted a scheme that provides a balance between specification standards and two alternatives: performance and systems-based standards. This would allow effective and flexible means to continuous health and safety performance improvement. Mine operators, regulators and politicians could then go beyond thinking that compliance alone equals strong safety by creating a proactive system that emphasizes continuous improvement. By adopting performance and systems-based standards, exemplary safety and health performers can be recognized, allowing regulators to focus their efforts on those without sound occupational safety systems and who have substandard safety performance. Mining Engineering, 2011, Vol. 63, No. 7, pp. 77-82. Official publication of the Society for Mining, Metallurgy and Exploration, Inc.

Jan 1, 2011

By Crystal Poon, Paul Matlashewski, John Morkeh, Kathryn Dorfschmidt, Jose Carvalho, Chad Williams

Rockfall hazards are ubiquitous in mining environments making their control critical for safe mining operations. The complex processes involved in rockfall events necessitate a probabilistic modeling approach with well-calibrated material properties. The controls designed to mitigate rockfall hazards need to be reliable, efficient, and safe to deploy to meet the constraints present at an active mine. This paper presents an innovative solution to rockfall at Rio Tinto’s Bingham Canyon Mine. The solution incorporates the site-specific calibration and creation of a predictive rockfall model with the design, field testing, implementation, and monitoring of the rockfall controls.