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Anomalous geologic or stress conditions ahead of the longwall face can cause great harm to both the individual miner and the mining operation as a whole. The U.S. Bureau of Mines has been developing seismic tomography techniques to image the panel ahead of the face. This paper presents the results of a field effort in which a 60-m (200-ft) segment of a longwall panel containing a fault zone was surveyed daily as the face approached. Stress distribution, geologic structure, and dynamic elastic properties within the panel were plotted and compared to static laboratory measurements. The surveys successfully imaged an anomalous stress concentration, likely influenced by the presence of the fault zone. The calculated dynamic physical properties generally agreed with laboratory measurements.

Jan 1, 1995

By A. Pezzuto

"Pipes are used on mine sites in a variety of applications including transport of slurry, conveying clean and processing water, and in mine dewatering. Mine waters and slurries can cause pipe wear and failures via several mechanisms (or combinations thereof) such as abrasion, scaling, and corrosion. Polyethylene (PE) pipe materials have grown in popularity over the past several decades due to their chemical and mechanical properties (e.g., inertness, flexibility, relatively low density) and low cost. While PE is generally resistant to corrosion, it is subject to abrasion. To combat this, a novel, rubber-like liner is in development. In addition to comprehensive abrasion testing, however, the liner must be evaluated to see how it performs under other conditions. Here, a brief field study is described that tested PE pipes with the new liner against traditional PE pipes to specifically assess mineral scale buildup. The study was conducted in the Reiche Zeche study mine in Freiberg, Germany in six different locations with varying water qualities and flow conditions. INTRODUCTION Water and slurry conveyance are major operations on and around mine and mill sites, from mine dewatering, to tailings transport, to water treatment processes. Conveyance systems in such applications can include great lengths of pipe materials along with pumps and monitoring instruments, and thus represent significant capital investments. Due to the variability of the physical and chemical properties of water and slurries, pipe materials are subject to a wide range of conditions. These can cause pipe wear and eventually failure leading to serious economic, environmental and social, consequences. While pressure-induced pipe failures (e.g., ruptures or ""bursts”) can be immediate, most failure mechanisms involve gradual processes. Scaling and sedimentation can present major problems for pipe systems conveying highly mineralized waters. Sedimentation generally refers to the deposition of suspended solids, such as sand, clay, silt, or organic matter onto pipe surfaces. This phenomenon can occur due to a decrease in water velocity or particle collisions with the pipe wall. Scaling, on the other hand, commonly refers to the deposition of precipitated mineral salts (including oxides and hydroxides) onto pipe surfaces. Mine waters often have extremely high ion concentrations (i.e., high dissolved solids content) due to their interaction with enormous surface areas of minerals, which are exposed during mining and processing operations (Brown and Barley, 2002). As these waters are transported, slight changes in temperature, pressure or chemistry (e.g., pH or ORP) can cause instability with respect to ion solubility such that salt precipitation begins to occur. “Seed” crystals can rapidly grow and attach to pipes, either due to local surface phenomenon near the pipe wall (e.g., which can promote coagulation) or sedimentation of the precipitated solid. Whether due to suspended or precipitated solids, as the solids begin to stick to pipe walls, “aging” or hardening processes can commence; and the build-up of scale can become self-perpetuating as the scale itself provides an attractive “nucleus” for further attachment of particles or crystal growth (Muryanto et al., 2014). Over time, scale-buildup reduces the effective pipe diameter, which can ultimately result in decreased flow velocity, clogging and, in some instances, bursting (Dirany et al., 2016)."

Jan 1, 2017

By David P. Kimball, Dalva L. Moellenberg

On May 21, 1990, EPA released its Strawman II draft program for mining wastes. It proposes to expand RCRA regulation of mining operations to include materials other than wastes. Strawman I1 would establish strict standards for the states to follow, rather than technical guidance. It proposes to establish performance standards; design criteria; monitoring requirements; and corrective action, closure, post-closure, and financial assurance requirements. It suggests "pollution prevention" concepts for mining operations. This paper explores the Strawman II proposals, particularly the technical criteria, and addresses several of the important concerns raised by industry.

Jan 1, 1991

By R. L. Kloberdanz

Peruvian legislation requires the preparation of an Environmental Impact Study (EIS) for new and expanding mines/beneficiation facilities and the preparation and implementation of an Environmental Adjustment and Management Program (PAMA) to control and mitigate environmental impacts associated with existing mining/beneficiation activities. Shepherd Miller, Inc., developed guidance documents for preparing an EIS and PAMA for Peru's Ministry of Energy and Mines and presented workshops to Peru's mining industry on preparing an EIS and PAMA. This paper discusses the process and approach taken and the results.

Jan 1, 1998

By J. E. Kulas

Red Dog is a Mississippian to Permian aged sulfide deposit located in the western Brooks Range north of Kotzebue, Alaska. It belongs in the family of black Shale hosted sedimentary exhalite deposits but lacks classic sulfide sedimentary textures. Pervasive silicification, and a significant portion of the mineralization, is replacement in nature. An extensive feeder vein system cuts the footwall and the exhalite package. A Jurassic to cretaceous age compressional event has repeated the ore section through thrust faulting and folding. The orebody contains 77,000,000 metric tons averaging 17.1% Zn, 5.0% Pb and 82 g per metric ton of Ag. Weathering has locally altered the sulfides to sulfates and formed elemental sulfur.

Jan 1, 1992

By E. R. Palowitch

On February 5, 1973, Eastern Associated Coal Corp began shortwall mining in their Federal No. 1 Mine, thus marking the first attempt in the United States at modern shortwall mining, i.e., using a continuous miner to extract coal open-ended from pillars 100 to 200 feet wide, under the protection of a self¬-advancing roof support system (1)1/. Since then, four additional shortwall faces have been operated. While the number of face-years of shortwall experience in the United States is limited, this experience has been anything but uniform. Differences in operator motivation, coalbed parameters, geologic conditions, panel dimensions, and face equipment all have contributed to a wealth of knowledge which can provide guidance for the design of future shortwalls. The purpose of this paper is to review the history of shortwall mining in the United States and to assess its value to the U.S. coal industry in terms of the health and safety of the miner, the percentage of coal recovered, coal production, worker productivity, and relative cost performance.

Jan 1, 1976

By W. R. VanSlyke

Scrubbing is gaining increasing recognition as a valuable tool in the treatment of Mesabi Range intermediate iron ores. In general, the earliest washing plants included log-washers in their various flowsheets. While log-washers certainly did impart a degree of scrubbing to the crude ore, such treatment bears little resemblance to the type of scrubbing being practiced today. At the time that these early plants were erected, only the true wash-ores were being processd. ("Wash-ores" are defined as crude ores in which relatively coarse chunks of almost completely liberated iron are found in a matrix of loosely-consolidated fine sand.) To treat ores of this type, sizing at approximately 65 to 100 mesh was sufficient to produce a merchantable concentrate. As crudes were being treated in which there was little "locking" of iron and silica, log-washers tended to disappear and large screens and classifiers took their place in Mesabi range flowsheets. The "screening and classification" type of flowsheet 'had its greatest usage in the 1945-55 period, generally speaking. During this same period, many operators found it necessary to supplement the "wash-ore" type flowsheet with heavy-media treatment.

Jan 1, 1959

The initiation of a panel cave is an extremely important and infrequent event in the life of a large underground caving operation. A new cave was initiated at the Henderson Mine in 1991, 15 years after its first cave had been developed in 1976. The original cave was started after a half billion dollars had been invested in the development of the mine, mill and 23 km haulage system. Many things had changed since 1976, the most significant of these being much lower realizations for molybdenum. In 1976 the high demand for molybdenum and uncertainty of caving characteristics, formed the basis for a very conservative cave initiation sequence with miles of boundary weakening and inspection drifting. In 1991 the highly competitive molybdenum market in conjunction with 15 years of caving experience made for a very different mining climate.

Jan 1, 1994

By James P. Ludwig

While we are all aware of the need for reclamation of mine sites, few managers and engineers seem to be aware that good reclamation begins with the earliest plans for mining and processing of ores. Far too often the attitude that reclamation is an add-on to worry about at the end of the mining process dominates the thinking of mine engineers and management, A common result is that the reclamationist can be faced with mining and waste disposal designs that are nearly impossible to deal with effectively from an ecological perspective. Everyone of us has been victimized by the down time and maintainence cost that resulted from the purchase of an outwardly attractive, but poorly designed piece of equipment. When confronted by design defects in equipment, a distraught owner can always trade it in, call a consumer advocate, or follow up one of the "lemon laws" at either the federal or state level. A poorly designed mine for reclamation purposes usually cannot be treated either with ease or cost effectiveness. Good reclamation can be effectively prevented by the designs used when the mine was planned. The purpose of this paper is to share some of the experiences our firm has had with reclamation projects at mines in the Upper Midwest as these were influenced or controlled by mine design decisions. My aim is to sensitize mine planners and managers to planning processes they should consider, and hopefully use, early in the mining process to assure successful reclamation during and after mining. Many of the examples I will cite are from experience gained at the recently closed Jackson County Iron Company taconite operation at Black River Falls, Wisconsin. I am particularly grateful to Mr. Vern Metzger, mine manager at JCIC, for his unflagging support of good reclamation practices, employee training programs (which have included reclamation techniques), and his forebearance to put up with our group of ecologists. I realize that this was a time when there were significant internal and external pressures to cut all costs including reclamation efforts. The collaboration has been successful as you will soon see.

Jan 1, 1984

By W. Fletcher

Startup of a new plant is a very interesting time. It generally is also a very demanding and often frustrating period. Startup problems can become serious ii they impede the early achievement of full plant production. Raw materials are wasted, manpower is unproductive, field modifications can be extremely expensive and market commitments may not be met. This paper outlines a well proven and highly successful approach to eliminating many of the problems and frustrations often experienced in plant startup. The procedures and methods summarized in the following paragraphs have been developed over a period of 25 years during which some 90 plants were started up.

Jan 1, 1981

By John M. Gullbert

It is the task of this portion of today's session on the new meaning of regional tectonics in the search for ore districts to discuss known interactions of tectonics and ore deposition in the 'new global tectonics' context. I will speak particularly about known applications of the recent tectonic advances to ore finding. Stated yet another way, it's getting on in time toward the "put up or shut up" stage-¬and I would not be here if I thought that the new tectonics were not an effective present matrix for ore finding. Before delving into specific geologic relationships--and I propose to discuss mainly the evolution of an idea which may reveal the presence of a major copper deposit on mainland Mexico--I must note that there have been no published accounts that I know of which assert that a particular discovery has been made soley and specifically because of an interpretation based upon mechanisms directly linked to sea floor spreading or plate tectonics. It is nonetheless true" that several major exploration efforts are based upon such interpretations, and, as is normal when exploration ideas are involved, one does not wish to call attention to an advantageous position in a highly competitive business. Little might be expected to have been announced in so fast-moving and potentially lucrative an area. Another point which needs to be made is that people such as B. S. Butler (1933), Billingsley and Locke (1935 and 1941), Harrison Schmitt (1935), and more recently Mayo (1958) have been working for decades with the tectonic expressions of the emergent tectonics without recog¬nition of the driving forces or the unifying tectonic concepts

Jan 1, 1971

By Cal D. Iles

Decreasing ore grades and increasing labor and material costs have seriously eroded the economic vitality of many mining operations. Coupled with global economic stagnation and recession in the early 1980's, these conditions have forced reevaluation of operating strategies and methodologies with the objective of remaining competitive in a world marketplace. A concept offering large potential benefits is hardrock portable crushing and conveying. Implementation of this system at Duval Corporation's Sierrita open pit copper-molybdenum mine (Figure 1) has significantly reduced mining costs, becoming a major part of Sierrita's cost reduction strategy. Located 48 km south of Tucson, Arizona, the 209 000 t/d property has one portable 60x89 gyratory ore-crusher in operation with tentative plans for two additional units.

Jan 1, 1985

Mine design and selection of ore processing capacity depend upon a correct estimate of the grade-tonnage distribution. The estimate must reflect what can be recovered and processed. The McCoy/Cove operation in central Nevada, USA, is a gold and silver mine. Case studies of recoverable reserve estimation for gold and silver were made using multiple indicator kriging and the log-affine variance correction. From this model, the grade-tonnage distribution was constructed. Optimal pits were generated by utilizing the distribution, and the results were compared with the pit generated by ordinary kriging. Studies indicate that the proposed method for multi-metal recoverable reserve estimation is more accurate than ordinary kriging in terms of both tons and the grade. Using recoverable reserves for mine design will maximize global recovery of mineral resources.

Jan 1, 1997

By Angus Maxwell, Jacob Grasmick

As the tunneling industry continues to adopt Tunnel 4.0, digital twins of the tunnel construction site are becoming standard requirements for tunneling projects. However, the benefits of these remain unproven to many practitioners. The paper discusses the various implementations of digitalization and describes efforts to combine all data types to analyze the relationships between influences, predictions and performance in a single digital platform. This includes data pertaining to investigations, design, construction, monitoring and post-construction asset performance and management. Based on 16 years of global tunneling projects the paper aims to quantify the tangible and intangible benefits of such systems. Using a number of real examples, the paper describes where opportunities were taken and where they went unrealized. Challenges and considerations for both procuring and developing these digital twins are also discussed.

Jun 13, 2021

By Kimberlie Staheli

A new sanitary sewer was installed in Pleasant Hill, California using microtunnelling methods. The project consisted of 693 meters of 1372 mm and 1981 mm concrete pipe. A Herrenknecht AVN 1200 was used to install the nominal 1372 mm pipe in three drives. The machine was then fitted with an oversized shield used to install the large diameter pipeline. This articulated shield allowed the excavation of a 2362 mm diameter hole with a 1524 mm machine-- a technique new to North America. This paper reviews the design considerations for the articulated shield and reports on the project challenges and solutions to overcome these challenges.

Jan 1, 1995

By R. S. Hearon

The image of the open-pit miner in the eyes or the Environmentalist has never been very outstanding. The phosphate industry, whose history in Florida reaches back to the late 1800's, can-not be credited until recently with a large number or accomplishments in terms of protection or the environment to change this image. This lack of action was not deliberate or in opposition with the desires of the public. In the formative years, there was little or no public and the companies found it necessary to build towns to house their employees and their families, towns which remained in existence until the late 50's and early 60's or formed the core of present large communities. Neither these pioneers nor most subsequent resource developers considered themselves un-thinking spoilers, nor were they so regarded by their contemporaries. Instead, they acted in a manner consistent with their environmental circumstances and intellectual heritage. Early Americans did make mistakes in using the land but the mistakes became apparent only in the opinion of later generations. Over the past five to ten years, there has been a new self-awareness in the industry with regard to environmental responsibilities brought about, in part by a continuing onslaught of new regulations with jurisdiction over our activities. Part of the new regulations are aimed at industries as a whole while many, particularly state regulations, pertain specifically to the phosphate mining industry. Why all the new regulations? The reasons are encased in a complex web of activity but stem primarily from a new public awareness of its environment. More and more of our youth have become interested in the environmental science areas such as biology and ecology. The tremendous growth rate in both the population and industry has made personal issues out of subjects such as atmospheric inversions and water shortages which previously were abstract concepts. The State has grown from a population of 1,500,000 in 1930 to approximately 9,000,000 people today. This personal impact and general lack of knowledge on the part of the public concerning economics has resulted in big business no longer being held in awe, often in contempt and generally in suspicion where environmental concerns are encountered.

Jan 1, 1978

By D. Kumar, R. J. Sweigard, J. Silva

The Forestry Reclamation Approach (FRA) recommends that the upper 1.22 m (4 ft) of spoil material on reclaimed surfaces should be left as uncompacted as possible to facilitate efficient tree root growth. However, the main concerns about applying the FRA to steep slopes is that the upper 1.22 m (4 ft) of loose spoil material could cause instability. Successful application of the FRA on the flat and rolling surfaces precipitated this investigation. Details of a field investigation conducted at a steep-slope mine site are available in an earlier publication (Kumar and Sweigard, 2011). A total of 70 survey monuments were driven into the slope in a regular pattern to monitor any type of slope movement. Quarterly surveying of the monuments were done to quantify slope movement, either horizontally or vertically. The methodology developed in this research for field slope movement monitoring was validated using computer model results. Analytical models based on the limit equilibrium method (LEM) and numerical models based on the finite element method (FEM) were developed for slope stability analysis. The LEM analysis was done using the Geo-Slope/W program following the simplified Bishop method. However, numerical models were developed using the PLAXIS computer program following the Mohr’s Coulomb failure criterion and strength reduction technique. The slope stability analysis was performed for two different scenarios: first with the top 1.22 m (4 ft) of loose graded spoil material and second without top loose graded spoil material. Finally, the field investigation results were compared with stability analysis results. Both of these approaches showed that application of the FRA on steep slopes is not causing any significant instability problems, due to 1.22 m (4 ft) loose graded spoil that would not exist otherwise for overly steepened slopes.

Jan 1, 2013

To generate a most profitable ultimate pit limit is generally the first step in mine design. This paper presents a new graph theory oriented, optimum ultimate pit limit design algorithm which will maximize the total undiscounted net profit. This algorithm performs much better than the well known Lerchs-Grossmann algorithm, in terms of the reduction in computation time and computer memory requirements. This algorithm operates on many directed trees in a graph, where each vertex in a tree represents a block in the mine model. The formation of each directed tree is based more on the ore-waste support concept than the geometry constraints alone. The general procedures of the algorithm, programming considerations and two case study results are discussed in the paper.

Jan 1, 1990

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 S. Pollak, J. Rickard

The Long Baseline Neutrino Facility Far Site in Lead, South Dakota is currently under construction and involves drill and blast excavation of the largest and deepest caverns in North America. This paper will review how the geotechnical risks are being managed through careful consideration of excavation sequence, completion of exploratory pilot tunnels, implementation of a robust instrumentation and monitoring program, and validation against the design. Aside from having a cross section of 5,900 square feet and being situated at a depth of one mile, the caverns also employ a unique permanent rock bolt solution which underwent a significant pre-production pull testing program involving varying installation methods and being subject to blast vibrations. The behavior of the schistose rock mass and performance of the ground support are being continually monitored throughout the construction phase.

Jun 13, 2023