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By Kostas Kaklis, Zach Agioutantis, Robin Flattery

Pillars are used as the primary support structures for underground mining to maintain stability by supporting the over laying strata. In the case of horizontal seams, the pillars are typically subjected to axial loading due to the weight of the overburden and/or abutment stresses, while in the case of inclined seams they are subjected to oblique loading due to both the vertical and horizontal in-situ stress.

By STEVEN J. SCHATZEL, Zoheir Khademian, KAYODE M. AJAYI

The integrity of unconventional shale gas well casings positioned in the abutment pillar of a longwall mine could be jeopardized by longwall-induced deformations. Under such scenarios, the surrounding fracture networks could provide pathways for gas flow into the mine, creating safety concerns. To provide recommendations for developing guidelines that ensure a safe coexistence of longwall mining and unconventional shale gas production, this study uses a discrete fracture network (DFN) model to evaluate the impact of parameters that could affect potential shale gas flow into the mine in the event of a casing breach. These parameters are evaluated using a conceptualized DFN realization that is representative of the fractured zone in the overburden, and the range of parameter variations are within values validated with field measurements.

Mar 1, 2023

By Jean-Michel M. Rendu

Increasingly, geologists use geostatistical methods to evaluate drilling programs. The complexity of the methods varies with the nature of the available sample information, the objective of the statistical analysis and the geologist's experience. Occasionally, estimating the average sample grade is all that is required. In other instances a semivariogram calculation may be considered. If sufficient data is available, the geologist may wish to estimate blocks or panels of complex shape, using the kriging method of evaluation. Historically, the use of geostatistics by geologists has been limited by a number of factors, most significant being the difficulty in accessing and using computer programs needed to complete the necessary studies. Geologists are often working in remote areas from which electronic communication is unreliable, if not impossible. Even when access to computer programs is technically possible, the costs incurred in accessing and using these programs are often considered prohibitive. In many instances using the programs requires an understanding of computer systems far beyond that which a field geologist can justifiably be interested in acquiring and maintaining.

Jan 1, 1984

By W. G. Willson

Low-rank coal (LRC) drying processes are generally categorized by operating temperature, drying environment and type of feed (either sized or ground coal). Within these broad categories, drying processes differ according to the type of drying equipment and methods of quenching and stabilizing the dried products. This paper focuses on the produce quality of various LRC drying processes including conventional low and high temperature evaporative drying and non-evaporative, hydrothermal drying. The former may be preferred if the dried product can be utilized immediately, but moisture re-absorption, spontaneous heating and fines production during handling are problems associated with longer term storage, transportation and utilization. Methods for reducing these problems are discussed. Hydrothermal processing is an advanced technology featuring high pressure, non-evaporative drying, which solves stability problems by producing a liquid fuel.

Jan 1, 1997

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. Frank Alsobrook

DOUG HALBE: Thanks, Terry. And in spite of your introductory comments, I'm going to attempt to continue our hallowed tradition of saying nice things about the speakers. This is really a serious comment now. We, as mineral processing and mill people, don't often talk to people outside our general operating area. One thing that we've tried to do in this operators' symposium is get speakers from various types of plant operations to help illustrate all the things we have in common. Our next speaker is from the industrial minerals area. I think there's a lot to be learned from industrial minerals operations. Some of the people in the last session learned some things about fine grinding in industrial mineral operations. I was a little surprised to see people there grind to 2 microns. Our next speaker is Frank Alsobrook. Frank is another nonmetallurgical engineer. He has a degree in geology, a master's of science from the University of Wisconsin. He's had his own very successful consulting company for a number of years. This is your 11th anniversary, Frank? Very good. He's also the immediate past chair of the industrial minerals division. I think the folks at the speakers' table should be ashamed. You have been so rowdy that Frank chose to sit in the audience. [laughter] We'd like you to come up now, Frank, and tell us some things that you've seen that might be useful to us. INTRODUCTION FRANK ALSOBROOK: The three topics addressed briefly are (1) teamwork and operations modeling, (2) the pitfalls of capital conservatism, and (3) the potential for by-product recovery. Ideas for improvements in these areas are not unique to industrial minerals but apply to metal mining and processing operations, as well. Several additional topics are suggested at the end of the paper.

Jan 1, 1998

By F. G. Crack

This paper is based on the philosophy that the management structure and strategy required for mine construction and development projects are different from that required for routine production and maintenance operations in a mine. The purpose of this paper is to present an integrated approach to the management of mine development projects. This paper highlights the four major aspects of the integrated approach. First, a brief review of the various types of contract documents is provided. Second, the management organization of a project is discussed. Third, the project manager's role and the field supervisor's responsibility are briefly outlined. Finally, the use of scientific techniques for planning, scheduling, executing, and controlling projects is presented. Each of these aspects is important; however, each by itself cannot be expected to bring order or unifying impact to the complexities involved in overall project management. When all these aspects are coordinated, the result will be a sore successful project from conception to completion.

Jan 1, 1982

By Emily Sarver

"Across all sectors and commodities, a common theme is driving progress in raw resource supply: sustainable development (SD). Over the past few decades, the mining and minerals industries for their part have undertaken significant and intentional changes at every level to become more responsible — no longer to just their shareholders, but also to the environment, to the communities in which they operate and to society at-large. Led by some of the global majors, these industries have indeed helped to define and operationalize the basic principles of sustainable development. Now in the midst of a full-on cultural shift, they are also key players in the continual effort to re-examine and calibrate practices to meet dynamic and increasingly complex objectives.SME’s technical position statementAs a home for so many technical experts and practitioners, SME has long recognized the importance of a commitment to sustainable development by the mining and minerals industries. In April 2016, the Society formally adopted a technical position on the topic following years of participation in, and support for, related activities. The full position statement appears below. It was drafted, revised and presented for approval to the board of directors by SME’s Sustainable Development Committee.Statement of Technical Position on The Mining Industry and Sustainable Development:• The National Environmental Policy Act of 1969 (NEPA) and the Surface Mining Control and Reclamation Act of 1977 (SMCRA) imposed considerable environmental restrictions on the mining industry; SME has always reinforced strict adherence to the laws.• In 2002, SME established a Sustainable Development Committee to lead its efforts in this area and to propel the organization into global prominence.• SME is a signatory to the Milos Statement of 2003 on Sustainable Development, so it is committed to providing scientific, technical, educational, and research skills in minerals, metals and fuels.• SME recognizes that SD programs adopted by the industry have a tangible return on investment through brand recognition and loyalty, facilitation of permitting, reduced occurrence of community protests and vandalism and diminished political risks.• SME actively promotes educational programs that encourage professional growth and interaction with the engineering professional community through books, articles, symposia, short courses and/or conferences on sustainable development in the mining and minerals industries.• SME has developed abundant expertise to provide balanced advice to government bodies, congressional staff and other interested organizations."

Jan 12, 2017

By W. C. Lacy

It is the responsibility of educators to look ahead and prepare young engineers and scientists to cope with industrial and social problems of the future. We are faced with a review of history as well as prophesy of the future. The mining industry exists in a "bubble" with little interaction or communication with the outside. This isolation must be broken down if the industry is to survive in the U.S. and Canada. The ability to communicate with the general public and public officials is essential. Many changes are occurring that will require readjustments in technology and staffing. Aging population will result in raising retirement and increasing available workforce. This may force shorter working weeks to supply additional jobs. Environmental concerns will likely direct more attention not only to these concerns during mining, but to planning for post-mining land usage. Retraining and up-dating educational programs are required to cope with these changes.

Jan 1, 1994

By Feida Wu, Yuhang Liu, Huimin Gao, Yuhan Song, Zhi Liu, Zijie Ren

In the process of quartz purification by calcination water quenching, the different expansion rates of gangue minerals and quartz were used to produce cracks or remove fluid inclusions, which is conducive to subsequent purification. However, the role and mechanism of calcination-water quenching are still lacking in research. In this paper, the position of calcinationwater quenching in gangue quartz purification process was adjusted and the removal effect of calcination-water quenching process at different nodes in the process was explored. The results show that the purification effects of grinding-calcinationwater quenching-classification-acid leaching process and grinding-classification-acid leaching-calcination-water quenching process were relatively good. The main reason is that calcined water quenching can make quartz produce cracks, which are more rough. At the same time, calcined water quenching is located after grinding, which has a larger specific surface area, pore volume and pore diameter, and has a strong adsorption capacity for acid solutions.

Nov 2, 2023

By Jerry M. Whiting

Greater awareness of the increasing need to develop supplementary energy sources is accelerating us towards many basic decisions regarding future utilization of mined energy materials -- uranium, coal, oil sands and oil shale. The latter material comprises a major potential source of oil which will require creation of unusually large and low-cost underground mining systems. In this paper, the author briefly outlines and analyzes several of the factors which continue to provide the somewhat unique character of oil shale nine planning and mine operation.

Jan 1, 1974

By A. P. Mehta

The role of microorganisms in the leaching of metal sulfides is well established (Torma, 1977; Murr, 1980). However, this established knowledge applies mostly to chemolithotropic microorganisms such as Thiobacillus ferrooxidans which function optimally in leaching catalysis between 25-35° C, and in a pH range of 2-2.5. Although leaching with thermophilic microorganisms capable of extending the range of catalytic viability beyond 35° C is also documented, there are few if any attempts to optimize or extend sulfide concentrate leaching with thermophilic microorganisms. When mixed metal sulfides or other materials having different rest potentials (referenced to the standard hydrogen electrode, SHE, in the electromotive series) make contact in a conducting, aqueous medium, the contacting members will act as an electrochemical cell, with the member having the higher rest potential assuming the role of an electrical cathode. In leaching reactions involving such galvanic couples, the cathode becomes passivated, while the anodic member reacts vigorously due to the electro- chemical reaction which occurs (Hiskey and Wads- worth, 1975). Serry, eta1 (1978) observed that when chalcopyrite and pyrite were in intimate contact in natural ores, the chalcopyrite reacted vigorously by galvanic conversion as a result of the higher rest potential (~ 0.63 V) as compared to the chalcopyrite (~ 0.53 V). In addition, it was postulated that because of the elemental sulfur which can form on the anodic chalcopyrite in this galvanic conversion process, reactions in acid-bacterial medium would be expected to have accelerated copper extraction because of the conversion of any sulfur product layer on the chalcopyrite anode to sulfuric acid according to the following general reactions: [MS?M2+ + S° + 2e- (1) and 2S° + 302 + 2H20 bacteria?-2H2SO 4 (2)] where M in reaction (1) designates the metal (or metals in the specific case of chalcopyrite) to be released to solution by galvanic conversion.

Jan 1, 1982

By Robert P. Moodry

It was attempted to revitalize an old sulfide leach dump by increasing the oxygen content within the dump. Compressed air was introduced into the old dump. This was accomplished by drilling 300 foot angle holes into the dump surface with an Aardvark drill which holes are then cased with 1-1/2 inch perforated PVC pipe. Compressed air is injected through these cased holes during a 10 day rest cycle. The second case consists of bedding perforated polyethylene pipe at the interface between the old dump surface and the next Lift of a new dump. Compressed air is then blown through the bedded perforated pipe on a continuous basis while leach solution is applied.

Jan 1, 1976

By G. K. Derby

Paper presents project results investigating current techniques for dragline wire rope removal and the development of less hazardous means of performing the task. The cannon is the most prevalent method used in American surface mines. A cannon test program was conducted that used 40-and 50-grain primer cord to establish force produced using a 56-pound projectile. Socketlwedges were separated to establish separation force data. Two alternative removal methods, pendulum ram and portable hydraulic pusher, were developed and tested. Both provide sufficient force to effect separations under normal conditions on draglines with up to 78- cubic yard buckets.

Jan 1, 1984

Several years ago, North American mining companies began to realize they needed to expand their spheres to remain viable. This strategy has been successful, according to Robert W. Schafer. Today, companies from other continents have also recognized the need for an international view for long-term growth and viability, he said. Schafer is vice president for exploration with Kinross Gold. He was the program chairman and moderator of the keynote session at the 1997 SME annual meeting, held in Denver, CO, Feb. 23-27. The theme of the meeting was "Minerals - Serving the Global Community." A record attendance of more than 6,000 people participated in the meeting, which featured 415 exhibitors occupying 582 booths. The title of the keynote session was "Corporate Perspectives on a Global Minerals Industry." Each of the three keynote speakers discussed a different perspective of a global minerals industry.

Jan 1, 1997

By John A. Cordes, Thomas F. Torries

INTRODUCTION Nonfuel mineral markets have always tended to be volatile due to the cyclical nature of demand and the difficulty of fine-tuning capacity and output levels. Experiences over the past two decades, however, have been especially perverse. This short volume attempts to provide insights into this era and some guidance for the future. The papers are linked together by their focus on issues of productive capacity. At the same time, they provide a useful description, explanation and evaluation of the industry's evolution and its implications for the near-term. The regnant pessimism of the 1980s was very much alive during the early months of 1987 when the theme of this symposium was formalized. Indices of real metal prices had only inched-up from all-time lows in 1986. The hemorrhage of corporate red-ink was still a powerful memory. Frustration with the apparent inability of closures and reduced capacity utilization to re-establish market balance was strong. To the more pessimistic, the industry appeared destined to a quarter century of persistent excess capacity and nonremunerative prices. The conditions to support this pessimism were readily apparent. Economic literature tells us that surplus capacity is a complex, usually unexpected and often long-lived phenomenon caused by the interaction of at least three factors. The first is a rising capital-intensity of production. The second is the presence of aggressive new entrants whose capacity additions are typically (1) trade- dedicated because local market absorption is low; (2) cost-competitive for natural or policy-support reasons; (3) heavily burdened by debt-repayment obligations; and (4) viewed as important sources of employment, regional development and foreign exchange. The third, and often decisive, factor is an unanticipated decline or stagnation in demand growth for the sector's output. The first two factors combine to increase competitive pressures and to raise the actual or perceived cost of idle capacity. Market rigidity reduces responsiveness to price signals and distorts the burden of adjustment. Demand atrophy exacerbates these pressures especially on unprotected producers in the higher quadrants of the global supply function. In the mid-1980s, evidence of the existence of all these factors were easy to cite. Culprits were often identified. Claims for protection, global sharing of adjustment burdens, and imposition of disincentives to new capacity regardless of inherent economic status were co-dominant themes with the buzz-words of "competitiveness" and "level playing fields." This, notwithstanding the suggestions of the same economic literature that excess capacity persists longest when interventionist remedies permit it to continue. Today, only eighteen months later, the mood is decidedly more buoyant and most analysts are cautiously optimistic about the next few years. Many informed analysts have concluded that the excess capacity of the recent past has disappeared. For the present, the marketplace seems to have restored a balance between supply and demand. That the adjustment took five or six years longer than anticipated attests to the dramatic structural changes which have characterized the industry. The implications of these changes for the future are unclear. Were the macroeconomic shocks, coupled with industry transitions, so extraordinary in magnitude and timing that experiences were unique? If so, the next years may hold more stable and cautious times for the industry. Alternatively, is the inherently volatile metals industry facing a future of cycles equally perverse in terms of amplitude and duration due to economic uncertainities and inflexible industry response capabilities?

Jan 1, 1989

By M. Deniz Turan, HASAN NIZAMOGLU, MÜCEVHER TURAN, RAMAZAN ORHAN

Tailings, or flotation waste, formed during copper production may be considered in the class of valuable wastes because of the amount of copper they contain. With the decreasing grade values of copper ores, the utilization of wastes like tailings that carry certain amounts of copper as secondary sources has become a necessity in both the economic and environmental senses. This study was carried out with the aim of using ammonium derivatives for the recovery of copper from tailings waste produced during copper production and utilizing their complex formation characteristics. In the conditions of six hours of leaching at 30 °C in the presence of 22.5 percent ammonium hydroxide and 100 g/L ammonium persulfate, 91.47 percent of the copper was transferred into the solution, while iron was not transferred, indicating that copper can be selectively recovered from tailings.

By B. J. Scheiner

The Federal Bureau of Mines has developed a chlorine-oxygen leaching technique for the recovery of metal values from lead-zinc sulfide concentrates. Lead, zinc, copper, cadmium, and silver extractions are in the 95- to 99.9-percent range. During leaching, the zinc, copper, cadmium, and silver are solubilized as metal chlorides, and lead is converted to insoluble lead sulfate. The iron contained in the concentrate is converted to insoluble iron oxide, and a majority of the sulfide is converted to elemental sulfur Minor metals such as copper, cadmium, and silver are recovered by precipitation with zinc dust. Zinc is then recovered from the purified zinc chloride solution by evaporation to dryness; the lead is recovered from the leach residue by brine leaching and crystallization to produce lead chloride. Recovery of zinc and lead metals by fused-salt electrolysis of the chlorides is being studied separately.

Jan 1, 1975

By Samer Sadek, Phoebe Cheng, Changmo Kwon, Myat Ohn

BART Facilities Standards (BFS) Structural Criteria is a living document that governs planning, design, and construction of all BART projects. Since its development, the document undergoes incremental changes and updates to reflect policy changes, changes in local, State, or national design codes and guidelines, advancements in engineering and technology, or based on the performance of past built infrastructure. In 2020, the BFS-Structural Criteria underwent a comprehensive update and was released with BFS version 3.2. This paper summarizes the updates to the Tunnels and Underground Structures Section of the Structural Criteria, and provides insights to the basis and logic of the requirements.

Dec 1, 2022

By Michael Edesess

The salt gradient solar pond has been the focal point of accelerating international attention and interest in recent months. Only recently have most investigators in the renewable energy field come to realize the versatility of the solar pond, and its ability to overcome certain problems usually associated with solar technologies. These realizations, together with clear demonstrations in Israel and elsewhere of its technical feasibility, have combined to bring the solar pond to the forefront of renewable energy technologies. The solar pond is a natural or site-built pond, about one to five meters or more in depth, which has been altered to retard the loss of absorbed solar energy. The absorbed solar energy is usually lost through upward buoyancy of the warmed water, followed by the loss of its heat to the atmosphere. The chief solar pond technology -the salt gradient, or "nonconvective" solar pond-prevents this upward buoyancy by means of a vertical density gradient achieved with dissolved salt. The deep waters in the solar pond reach high temperatures, up to and even above the boiling point of pure water.

Jan 1, 1981