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By William Gleason

The mining industry is a unique space. It is one in which geologists and chemists can intersect with computer and data science professionals daily. The industry requires expertise in not just mining and metallurgical engineering, but also electrical, mechanical, environmental and more. It requires expertise in worker health and safety, behavioral science, finance and economics, as well as human resources management. The locations of mining operations are often in remote corners, and for underground activities, they are unlike anything else in the world. The industry presents those who join it a wealth of opportunities, but often struggles to overcome incorrect perceptions of safety, labor and environmental standards, making it difficult to recruit and retain employees at a time of increased demand for mined materials.

Dec 1, 2025

By R. V. Ramani

Demands on available lands will continue to increase due to the projected increase in population and industrial expansion. Though there is an upper limit on the available lands, the multi-use nature of the lands will make it possible to meet these demands. However, this will not happen without adequate planning. Land uses can be broadly categorized as non-renewable and renewable. Lands with mineable resources can be dedicated at some point in time to the extraction of resources. Such a dedication, however long-term, is only temporary because of the non-renewable nature of the mineable resources. Implied here is that the land will be available before and after mining for other uses. Planning for such lands must have the objective that, as far as practicable, no non-renewable uses are pre-empted and no renewable uses are permanently destroyed. The primary aspects of this planning process will be addressed in this paper, These aspects include a discussion of planning responsibility, data needs and availability, the integration of mine planning and post-mining land use planning and a long-term plan for resource conservation and utilization. Minerals, together with agriculture and forestry products, are the primary sources of wealth. Therefore, to avoid land development that may pre-empt future mineral resource utilization, the local planning groups must be aware of the mineralization and mining potential. Much work needs to be done to identify and characterize the mineral resources. Even more work is needed in land use planning for lands with mineral deposits.

Jan 1, 1982

By W. M. Ma, Daniel W. H. Su, K. Centofanti, Yi Luo, W. L. Zhong, Syd S. Peng

1.1 INTRODUCTION When underground mining involves total extraction, it induces overburden strata movements. If not properly planned it causes surface subsidence and affects surface environmental conditions. Total extraction usually refers to longwall mining and room and pillar mining with pillar extraction. Surface subsidence has long been a subject of intensive research for scientists all over the world and considerable achievements have been obtained. However due to its difficulties and complicated nature, research into overburden movement has been thus far incomplete as compared to that into surface subsidence. Since surface subsidence is a manifestation of the results of overburden movement, the processes and mechanisms of overburden movement must be fully understood in order to establish the mathematical prediction models of surface subsidence. In this chapter the processes of overburden movement and its zones of movement in the overburden will be discussed. 1.2 PROCESSES OF OVERBURDEN MOVEMENT When total extraction is used, it produces a large void in the coal seam and disturbs the equilibrium conditions of the surrounding rock strata. The roof strata bend downward while the floor heaves. When the excavated area (or gob) expands to a sufficient size, the roof strata will cave. As a result, the overlying strata continue to bend and break until the piles of the fallen rock fragments are sufficiently high to support the overhanging strata. At this tie the overhanging strata no longer cave, but bend and rest on the underlying strata. Strata bending and subsidence develop upward until reaching the surface and forming a subsidence basin. The whole overburden strata and the surface subsidence basin will further go through a period of compaction and gradually become stabilized. Current knowledge regarding the process of overburden movement has been derived from several sources. One is the direct observation of the mined sections and their surfaces, another from field monitoring of strata movements in the overburden, and others from computer modeling and scale modeling in the laboratory. For example, Figs. 1.1 and 1.2 show the results of a borehole monitoring experiment (Borehole B-2) using the full profile borehole inclinometer and full profile borehole extensometer for lateral displacements and vertical subsidence, respectively (Conroy and Gyarmaty, 1983). The panel, 400 ft wide by 5000 ft long and 630 ft deep, was extracted from the Pittsburgh No. 8 seam which had an average thickness of 54 in. The face advanced from east to west. Curve A in Fig. 1.1 shows the inclination of the borehole when it was 45 ft ahead of the face at Position A (i.e., on the solid coal side). The total deviation of the borehole was 1/7000. The first shear movement occurred at 130 ft above the coal seam and appeared to have occurred along the bedding plane with large contrast of rock strata on both sides, i.e., sandstone vs. shale. When the face had passed the borehole 79 ft at Position B, the borehole deformed to assume a bow shape with a maximum deviation of 2.8 in. from the center line. Numerous shearing planes occurred and extended further upward. When the face had passed the borehole by 75 ft at position C, strata subsidence was measured. Fig. 1.2 shows that a strata separation as large as 4 ft occurred at 40 to 100 ft above the coal seam. Above this level, the strata subsided more uniformly with bedding separations within 1 to 2 in. Another example is the longwall mining with complete caving in the Soviet Union's Karaganda Coalfield (Kolebaeva, 1968). The coal seam was 6 ft thick and 154 ft deep. The immediate roof was the fine-grained sandstone interbedded with coarse-grained sandstone. Above this, there was sandy shale and shale. In order to monitor the process of overburden movement, 15 stations were established in a borehole (Fig. 1.3). The elevations of those stations were measured when the face was at various distances from the borehole. Fig. 1.3 shows the movement history of each station. For convenience of comparison, the movement history of each station was plotted on a common reference point as shown in Fig. 1.4. Clearly, the movements of strata from Station # 1 to #6 were nearly simultaneous, i.e., they behaved as a single unit. The strata from Station #7 to # 15 had differential separations, the maximum of which was 40 in. As the face passed by and moved away, strata separations in general reduced gradually. But strata separation between Stations #12 and #13 remained the same until the end of the monitoring period. The total bed separation between Station #7 and # 15 reached 11 in., approximately 18% of seam thickness, when the face was 132 ft beyond. Based on the above observations, the author developed a conceptual model of overburden movement due to underground longwall mining (Fig. 1.5). The above-mentioned two case studies illustrated that subsidence in the overburden strata propagates upward and subsidence velocity decreases from the bottom to the top. When the subsidence velocity at the surface reaches the maximum value, the subsidence velocity at the bottom portion of the overburden strata has decreased considerably and the strata have begun to compact. Bed separation occurs within a certain distance above the coal seam and reduces from the bottom to the top. When the face has moved away, bed separation reduces gradually, so that eventually some beds completely close and others partially close. Bed separation reaches the highest level when the subsidence velocity at the surface is at its maximum value. For instance in Fig. 1.4 surface subsidence velocity was maximum when the face was 38 to 44 ft past the point. At this time the total bed separation was maximum. Overall the strata directly above the opening are subjected to tension in the vertical direction. But above a certain level, all strata move nearly simultaneously. There is also significant shear movement along some bedding planes. 1.3 ZONES OF MOVEMENT INTHEOVERBURDEN After the extraction of a longwall panel or room and pillar section of sufficient width the strata in the overburden are subjected to various degrees of movement from the bottom to the top. According to the movement characteristics, the damaged overburden can be divided into four zones (Fig. 1.6). Caved Zone. After the extraction of coal, the immediate roof caves irregularly and fills up the void. The strata in this zone not only lose their continuity completely, they also lose their stratified

Jan 1, 1992

By Y. J. Wang

Editor's Note: Y.J. Wang's paper appeared in the September Technical Papers section. There were some inadvertent editorial errors in it. So we are reprinting it here. Abstract - This paper examines the ventilation network problem from a view point of solving a system of B equations in B unknowns, where B is the number o f branches in the network. Based on Kirchhoff s current and voltage laws, the solution to the general ventilation network problem must satisfy B network equations. In this paper, the air quantities and control-device pressures are chosen as variables and are grouped into B dependent variables (unknowns) and B independent variables, resulting in a system of B equations in B unknowns. Based on whether their variables are dependent or independent, the network branches are classified into f our types: five d, non-fixed, p-fixed, and q fixed. The ventilation network problem may include all four types of branches. There are .some conditions under which the problem as defined in this manner does not have a unique solution. To have a unique solution, the Jocabian matrix of the equations m us! he nonsingular. It then follows that: • the number of branches with independent air quantities must be less than or equal to the number of chords with respect to a spanning tree; •the subnetwork of branches with independent air quantities must not contain any cutset; and •the suhnetwork of branches with dependent control-device pressures must not contain any cutset. These three conditions must be met regardless of the values for the variables. In addition to the problem formulation, a solution procedure applying the Newton (or Newton-Raphson) method is outlined and illustrated with an example problem.

Jan 1, 1991

By M. A. Girts

Wetlands can be constructed inexpensively on mined lands to treat small flows of acid mine water. Metals are removed from the water by the wetland vegetation and indigenous bacteria. Full-scale field tests initiated at over 20 mine sites during 1984 and 1985 indicate that water quality can be upgraded to meet discharge standards with relatively minor maintenance requirements. Iron concentrations of 25-85 mg/L in the influent water fall to less than 2 mg/L during flow through a small wetland. Manganese can also be removed, though somewhat less efficiently. At the discharge, pH is easily raised to 6 by flow over limestone.

Jan 1, 1986

Application of flotation for the removal of hydrophobic compounds from soils was studied. Bench scale flotation tests were conducted on artificially contaminated soil, using both conventional mechanically agitated machine and flotation column. Flotation parameters tested include surfactant collector type, conditioning time, flotation time, surfactant dosage, pulp pH, solid/liquid ratio in conditioning and pulp temperature. It is found that with conventional flotation 74% removal of the contaminant was achieved from soil particles in the range of 75-830 µm; with column flotation up to 80% of oil could be removed from the 250-830 µm soil fraction, and 65% from the 75-830 µm fraction. Flotation was found to have considerable potential for cleaning up contaminated soils.

Jan 1, 1998

By Alexander N. Winchell

"Location. The iron formation of the Gogebic district (including the Penokee) comprises a narrow belt south of the western part of Lake Superior extending from Michigan for a considerable distance into Wisconsin. From the mouth of the Montreal River (about twenty-five miles west of Ashland) the iron formation is only about twelve miles distant, but it is about twenty miles south of Ashland. Beginning on the east at a point about eight miles east of Wakefield, Mich., it extends through Sunday Lake, Bessemer and Ironwood in Michigan, and thence south of west through Hurley, Wis., and only a short distance south of Mellen, Wis. About eight miles westward from Mellen, the formation disappears, but six miles further west it is known to reappear and continue thence for about eight miles. The total length of the range is about sixty miles, two-thirds of this distance being in the State of Wisconsin; but nearly all of the ore has been obtained from the eastern third of the district, which is in the State of Michigan.History. This iron range was first noted in 1848 by Dr. Randall, assistant geologist to Dr. David Dale Owen, while following the fourth principal meridian northward. It was also reported by Charles Whittlesey in an account of a survey made in 1849, and published by Owen in 1852. Analyses of the iron ore are given with the following account. ""The bed of magnetic iron ore south of Lac des Anglais is of extraordinary thickness,25 to 60 feet. * * In the wild and deep ravines where the Bad River breaks through the range, there is a cliff of slaty ore * * * probably three hundred feet thick. * * * I estimate more than one-half of this face to be ore, and in places the beds are from ten to twelve feet in thickness, with very little inter-mixture of quartz * * * . The position of the best exposures of ore which I saw is such as to require from eighteen to twenty eight miles of transportation to reach the lake."""

Jan 1, 1920

By C. West

Structured or embossed HDPE and LLDPE geomembranes have been available to mine owners and designers for over ten (10) years. As many owners and designers discover and demand the consistent high quality characteristics of this type of geomembrane due to the unique manufacturing process, the use of these materials in new mines, mine expansions and final closure designs has steadily increased. Structured liner materials are available for double lined and final cover systems and are revolutionizing the way ponds, pads and final closures are constructed. This paper will discuss the structured or embossed geomembrane concept and manufacturing process. Additionally, the paper will present comparative testing illustrating the major advantages of using this type of product in these types of applications. Both technical and economic advantages are illustrated. The cost savings include lower installation costs, less material used, and third party inspection times not to mention better performance. These new systems will be presented.

Jan 1, 2011

By Willard C. Lacy

Survival of the mining industry as a viable economic entity in the United States is being seriously threatened by declining grades of ore reserves, rising operational and capital costs, and increased governmental taxes, restrictions, and subsidizing of third world competition. Discovery of major high-grade deposits is becoming increasingly unlikely. International competitiveness of the U.S. deposits will depend upon 'Yankee Ingenuity', innovations in mining methods, metallurgical treatment, and financial arrangements, and a viable national strategy. This will require not only effective management for control of operations, but management that encourages breakthroughs in technology, financing, labor relations, and in public and governmental understanding. The mine geologist and the exploration geologist both have important roles to play in all aspects of this fight for survival of the industry.

Jan 1, 1984

By Robert L. (Original by) Llewellyn

Many of the problems that occur in the preparation plant originate from practices in the mine. Impurities in raw coal can be in the seam itself or from extraneous material taken in mining from the roof or bottom. In the case of underground mines, the choice of mining equipment will affect the size consist and the amount of extraneous material included with the coal. Also, governmental regulations concerning the degree of rock dusting, gobbing underground, and cleanup have increased the dirt in raw coal. Sulfur dioxide emission standards, on the other hand, are pressuring the coal industry to clean coal more thoroughly. Coal supplied for coking purposes is nearly all upgraded by washing, while for the largest market, electric power generation, a high proportion is shipped as a raw product with processing, in whole or in part, only necessary when excess impurities are mined with the coal. This chapter will deal primarily with plants that process or wash coal to some extent (Fig. 1) and only incidentally with mines shipping raw run-of-mine coal crushed to a top size of, usually, 51 to 102 mm (2 to 4 in.), with little, if any, other treatment.

Jan 1, 1981

By William H. Pomroy

This report describes research leading to the design, prototype fabrication, and successful in-mine proof-of-concept testing of two improved stench fire warning systems for underground noncoal mines. The stench system, widely used in underground noncoal mines to warn of fire or other emergency suffers several serious shortcomings, including the toxicity of the odorant leading to debility in miners; reactivity of the odorant with iron oxide, resulting in unreliable warning because the odor may fade when transported long distances in steel pipe; lack of control over the rate at which agent is released into the air-stream, resulting in some work areas receiving unbearably high stench concentrations and other areas being missed altogether; lack of visual indication of system status, valve positions, or proper system operation; and excessively long stench transit times. In 1979, the Bureau of Mines, U.S. Department of the Interior, began research to upgrade the stench warning system. Two systems were subsequently developed which offer significant advantages over current systems.

Jan 1, 1984

By Donald W. Foss

The Shiloh Church deposit is a very significant molybdenum occurrence in an ususual, perhaps unique, geologic environment. Work done to date indicate that several million tons of "ore" may be present, occurring as a matrix in limestone and dolomite breccias. Mineralized rocks cored to date are at or near the surface and the deeper resource potential has not been tested. The prospect is located in Polk County, north- western Georgia (Fig. 1). The "ore zone" was outlined by North American Exploration, Inc. (NAE) using geochemical prospecting techniques. Extensive geological work, including core drilling, has been conducted on the properties, together with geochemical and geophysical surveys. The geology, geochemistry and geophysics of the prospect are discussed. It is hoped that these data can be used to formulate exploration programs in similar terranes located elsewhere in the eastern U.S.A.

Jan 1, 1983

By R. W. Chadwick

Coal was discovered in South Africa in the mid 1830's. The earliest exploitation of modern times was probably in Natal where, in a letter dated 20 August 1842, a Captain Smith mentions that a wagonload of coal brought to Pietermaritzburg, was sold. Until the discovery of diamonds in 1867 and the Witwatersrand gold in 1886, coal mining satisfied a very small domestic demand. By 1889, at least four collieries were operating in the Middelburg-Witbank district, some 120 kilometres East of Johannesburg, and mining had star- ted at Vereeniging, about 50 kilometres to the South of Johannesburg. A map of South Africa is shown in Figure 1 and an enlargement of the main coal mining areas in Figure 2.

Jan 1, 1982

By W. Z. Choi

In our previous work, a population balance model describing the simultaneous processes of size reduction and mineral liberation has been developed. The experimental verification of this model, however, has been limited to a binary mineral system containing only one composite particle class. When considering multiple classes of composite particles, the estimation of model parameters becomes much more difficult. In the present work, a procedure for estimating model parameters for a multiple composite class model has been developed. Emphasis is placed on the direct experimental determination of these parameters. The physical significance of the breakage rate function and the liberation function in characterizing the liberation process is also discussed.

Jan 1, 1987

By Gordon B. French

In order to better understand the relation- ship of underground and surface oil shale processing systems, a block flow chart is presented in Fig. I. From this figure only modified in-situ and Room and Pillar underground mining are currently committed and into the Detailed Design and Construction phases. Figure II illustrates the times required (Federal land site) to bring oil shale operation into production. As this example shows, only those companies having progressed beyond the exploration stage have a chance to obtain oil shale production within the next 10 years. A more detailed breakdown of the oil shale development for those on private lands or having already obtained Federal lease lands is shown in Fig. III for shale oil development (without major regulatory changes).

Jan 1, 1981

By W. L. Josey

The Stibnite Project is an open pit/cyanide heap leach gold property located in the Yellow Pine mining district of central Idaho. The gold ore is in an oxidized zone of an epithermal deposit which is associated with a fault system related to Tertiary igneous activity of the region. The faults transect a roof pendant of metamorphosed sediments within crystalline rocks of the Idaho Batholith. Seasonal mining is at a rate of 3900 mt/d (4300 st/d) of ore with a 2:l waste to ore ratio. Gold and silver are recovered through a process of cyanidation, carbon adsorption and desorption, and electrowinning. Disposal of the leached ore requires chlorination of the residual cyanide.

Jan 1, 1984

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 Irina Chernyshova, Erik Larsen, Hanumantha Rao Kota, Vladislav Slabov, Garima Jain

The mining industry faces pressure to provide metals for the green digital shift using sustainable technologies. This study evaluates biosurfactants as collectors for ultrafine and coarser particles of hematite and malachite, aiming to improve the flotation of ultrafine particles.

Jun 1, 2023

By R. Mulyanto, M. Siray, A. Parhusip, F. Hartono

"PT Freeport Indonesia is preparing the Deep Mill Level Zone (DMLZ) mine to be the successor of the currently operating Deep Ore Zone (DOZ) mine. The DMLZ is block cave mine situated 500 m below the DOZ mine and approximately 1600 m depth from surface. Both of the block caving mines require draw point construction in the extraction level to extract the ore from caved area above. Learning from the experience in DOZ, the construction & maintenance of draw points in the production panels is a significant challenge in supporting consistent production.The average DOZ draw point construction duration is approximately 46 shifts per draw point. The time frame for construction is dependent on several variables; availability of the conventional forming system, material availability, and development tolerances. The repair of concrete floors and lintel sets causes production downtime. Reviewing the old DOZ draw point design, there is an opportunity to increase constructability, durability, and reliability of DMLZ draw points. This paper discusses how the DMLZ has improved draw point construction productivity and is on track to significantly reduce costs whilst increasing the quality by using the Six Sigma Improvement Method.Introduction The DMLZ Mine is part of the PT. Freeport Indonesia (PTFI) future Expansion to its underground mining complexes. It is the fourth vertical lift in the East Ertsberg Skarn System (EESS) deposit (Figure 1).Currently, it is under development phase.The DMLZ mine will be a block cave mine using an advanced undercutting method. The DMLZ extraction level will be approximately 1,600 meters below the surface on the 2570 level with column heights of roughly 500 m. The Undercut is on 2590 level, some 20 meters above the extraction level."

Jan 1, 2016

The knowledge of aggregate size under various chemical and hydrodynamic conditions is very important for selective agglomeration, flotation and water clarification processes. Traditionally, aggregate size measurements are conducted using an ex-situ technique or in a diluted suspension. In either case, the measurement occurs in an environment that does not resemble the actual conditions under which the aggregates are formed. In this study, an on-line scanning laser microscope has been used to study the coagula size of micronized coal suspensions as a function of pH, solids concentration and agitation intensity. A maximum aggregate size of 310 µ m was obtained under relatively quiescent conditions and at pH values near the iso-electric point (iep) of the coal. The aggregate size results compare well with the coagulation efficiency measurements obtained under the same pH conditions.

Jan 1, 1994