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By Galen G. Waddell

Several years of rock-burst research conducted by the Federal Bureau of Mines, in cooperation with the mining companies of the Coeur d?Alene Mining District, Idaho, in addition to progress made by others throughout the world, have led to a good understanding of the rock-burst problem. This paper describes conditions which have caused specific bursts, present capabilities of detecting stress buildup and bursts, control methods, and a suggested approach to analyzing any individual mine-burst problem.

Jan 1, 1970

By Richard Seal

Nabarlek is situated in the Arnhem Land Aboriginal Reserve about 270 km due east of Darwin in the Northern Territory of Australia. During the dry season (May to November) Nabarlek is accessible from Darwin over the Arnhem Highway-- a distance of 330 km. Throughout the wet season (December to April), except for a few days, access is provided by aircraft from Darwin to the Nabarlek airstrip. Because of the limited access during the wet season, reagents and supplies have to be stock- piled for six months on the site to maintain operations. With the mine and plant being remotely located on private Arnhem land with very limited access outside the site fence, operating personnel are flown to Darwin every six days for their days off.

Jan 1, 1980

By N. B. Aughenbaugh

Subsidence due to abandoned coal mines has received copious attention recently. This is a result of many factors such as the enactment of new mining laws and the effect subsidence has on land use over the mines. Prediction of subsidence features and the time aspects over supercritical extraction (i.e., longwall and high extraction ratio pillaring) is relatively accurate. However, predicting when subsidence will occur and the surface features' size and shape above subcritical extraction of room and pillar mining is not yet possible. This paper will discuss the factors that influence the time aspects of subsidence in room and pillar mining.

Jan 1, 1983

By Robert S. Lehto

Zinc concentrates received in La Oroya zinc refinery are marmatitic in nature, contain about 11% iron and traces of other metal values, Figure 1 shows the zinc circuit. The calcine from the roasted concentrates is leached in spent zinc electrolyte. Major part of the impurities is iron which has been oxidized to its trivalent form, This is the origin of the zinc leach residue for which the ZILERET process was developed and so named. The impure liquor from the leach is sent for purification and thence to electrolysis- zinc deposits on aluminum cathodes from which: it is stripped, melted and cast into slabs Typical assays of zinc calcine and leach residue are given in Table 1. Metal values contained in the leach residue, without counting any value of iron, amount to roughly $130 per short ton.

Jan 1, 1969

By Robert C. Maxton

The foundry industry is a basic source of structural component for all industry. Millions of tons of castings are produced annually in both ferrous and nonferrous alloys. These castings are subjected to a wide variety of heat treatments, finishing techniques, mechanical tests and machining operations. Through all of these steps the quality of the casting is of paramount importance to the end use of the product. The Quality Assurance Program at Minneapolis Electric Steel Castings Company is designed and established to provide a superior product for both original equipment manufacturers and the mining industry.

Jan 1, 1982

By William Gleason

"More than 6,300 people converged on the Colorado Convention Center for the 2017 SME Annual Conference and Expo and 119th National Western Mining Conference in Denver, CO on Feb. 19-22. Many of them crammed in to hear Douglas Silver deliver the keynote address to the conference.Silver is a portfolio manager for Orion Mine Finance, a private-equity fund focused on providing funding to advanced-stage base and precious metal projects and is one of the most respected voices in the field of mineral economics. Prior to joining Orion, he served as chief executive officer and chairman of International Royalty Corp., a global mineral royalty company, which he founded in 2003 and sold in 2011.Those who were hoping that Silver would deliver at least a bit of optimism during his 90-minute presentation got what they came for from the talk titled, “When are commodity prices going to rebound?”It marked the second time Silver has presented the keynote address to SME, the first was in 2008 and was delivered during the height of mining’s super cycle (ME, June 2008). In his 2017 address, Silver looked back on the previous 10 years and the massive contraction of the global economy that resulted from the great recession that began near the end of 2008.It has been a challenging time for the mining industry. About US$1.4 trillion was lost in the global mining stocks from 2011 to Jan. 6, 2016. Major mining companies exceeded $60 billion in write downs between 2012 and 2013 and investors lost confidence in the sector, putting the global mining industry into a bear market that has taken mining equities to historic lows.However, that was then and this is now.Using numerous examples, including rising commodity prices, a steady decline in the U.S. unemployment rate, increases in discretionary income and the Dow Jones Industrial Average, which topped the 20,000 mark for the first time ever in February, Silver theorized the current down cycle is near its end and the demand for metals and other commodities will see a sharp increase by 2025. He also noted that investors are beginning to rotate back into mining equities."

Apr 1, 2017

By J. Girard-Dwyer, J. Johnson, J. Whyatt

The choice of fragmentation method is one of the most fundamental aspects of mine design, and often has a major impact on the safety and economic viability of an operation. Almost exclusively, underground mining operations rely on either mechanical excavation or drill and blast techniques to extract rock. Each of these fragmentation methods has distinct advantages and disadvantages, and each is appropriate, and economic, for different mining conditions. However, the choice of fragmentation method can have a pronounced effect on the amount of damage created in the rock mass surrounding the opening. This paper reviews a number of case studies where both mechanical excavation and traditional drill and blast were used in underground mines. Ground support requirements in the mechanically excavated areas are compared to the support requirements in the blasted sections in order to demonstrate the potential safety and cost benefits of the various fragmentation methods.

Jan 1, 2003

By J. M. Wempen, M. K. McCarter

"Differential Interferometric Synthetic Aperture Radar (DInSAR) is a satellite-based remote sensing technique capable of measuring centimeter-level surface displacement with high spatial resolution over large areas. Regular monitoring of subsidence due to underground mine development is one potential application of DInSAR, and in this study, the application of DInSAR for subsidence monitoring is evaluated for two mining regions in the mountain west of the United States. In general, DInSAR has potential to identify the shape and extent of subsidence; in some cases, magnitudes and rates of subsidence can be defined. Importantly, the effectiveness of DInSAR for subsidence monitoring depends on the radar band (wavelength), the subsidence rate and the time between image acquisitions, and the topographic and vegetative surface characteristics. INTRODUCTION Differential Interferometric Synthetic Aperture Radar (DInSAR) is a satellite-based remote technique that can be used to measure small surface displacements. Under good conditions, centimeter-level displacements can be measured with subcentimeter accuracy (Buckley, 2000; Massonnet and Feigl, 1998). Additionally, DInSAR data have relatively high spatial and temporal resolutions. Pixels in Synthetic Aperture Radar (SAR) images can have a ground resolution as small as about 3 m, and images often include tens to hundreds of thousands of pixels and cover tens of kilometers. Regions are imaged regularly, and periods between images typically range from weeks to months. In DInSAR, phase measurements from two radar images acquired over the same region at different times are used to precisely measure relative distances (Rosen, 2014). Surface deformation, topography, and changes in the satellite position all contribute to differences in the length of the path that the radar wave travels in each image. SAR sensors use radar with relatively long wavelengths; L-band (24 cm wavelength), C-band (6 cm wavelength), and X-band (3 cm wavelength) radar are used most commonly. Because the wavelengths are long, small changes in the path length of the radar signal can be quantified by measuring the change in the phase of the radar signal between the images. In general, changes in the path length due to changes in the satellite position and topography are known or can be estimated, and centimeter-level changes in the path length due to deformation are measurable. This study evaluates the effectiveness of DInSAR for measuring subsidence in two mining regions in the mountain west of the United States. L-band data from the Advanced Land Observing Satellite (ALOS) and X-band data from the TerraSAR-X mission are evaluated. Imaging characteristics, including the radar band and the time between image acquisitions, are important for effective subsidence monitoring."

Jan 1, 2017

By S. K. Kawatra

Under normal conditions, a significant amount of pyrite is recovered in the froth during flotation of high-sulfur coal. In order to reduce this pyrite recovery, it is first necessary to determine the primary recovery mechanism, as different measures are required for reducing entrainment, locked-particle flotation, or true hydrophobic flotation. In this paper, evidence is presented which suggests that hydrophobic flotation is not the major mechanism for recovery of liberated pyrite, and that the bulk of the recovered pyrite is there either as a result of simple entrainment or by being physically locked with floatable coal particles.

Jan 1, 1991

By Peter Johnson, David Barber, Lachlan Henderson

"The traditional approach to rail tunnel fire safety design is to follow NFPA 130, which assumes a major tunnel fire could occur and requires bi-directional emergency ventilation. There is no regard to the impact of ventilation on fire growth and smoke production. In Europe and other parts of the world, the need for tunnel ventilation systems to provide smoke management in the event of fire is being questioned. The European Commission’s Safety in Railway Tunnels TSI is based on a philosophy that improved running capability (preventing fires and other events stopping the train in the tunnel) and elevated fire performance of materials means the chances of a major fire in a tunnel is highly unlikely, with only small fires expected, and no tunnel ventilation required. This approach is reinforced by the International Tunneling Association which has recently published an Engineering Methodology for Performance Based Fire Safety Design on Underground Rail Systems, which includes a methodology that does not require assessment of tenability in tunnels, but requires a scenario based risk assessment to be undertaken to determine overall fire safety measures. Recent research by the University of Edinburgh has shown that forced airflow from a mechanical ventilation system may promote fire growth and increase smoke volumes much more than with natural ventilation. Whilst the concept of no mechanical ventilation (i.e. natural ventilation) is a new concept for some, for many rail tunnels it is worthy of serious further consideration. RAIL TUNNEL SMOKE MANAGEMENT AND STANDARDS Smoke management using mechanical bi-directional ventilation systems has been a central part of the fire safety design solution under NFPA 130 for rail tunnels since 1982. The current version of the standard, NFPA 130: 2014, states that mechanical ventilation should be fitted to rail tunnels of length greater than 305 meters and an engineering analysis should be undertaken for tunnels of length 61 to 305 meters to determine whether mechanical ventilation should be fitted. However, this approach is not necessarily reflected elsewhere in the world. In Europe in particular, mechanical ventilation systems for smoke control within rail tunnels have taken a much less central role within the standards framework."

Jan 1, 2016

By Jerome F. Sheldon

The earliest recorded history in the use of belt conveyors in the United States is in O. Evans' "Miller's Guide" published in Philadelphia in 1795. Evans defines a conveyor as a "broad endless strap of thin pliant leather or canvas revolving over two pulleys in a case or trough." (Ref. 1) In this definition, pulleys are being used in a bulk material belt conveyor application. Pulleys used in belt drives can trace their origin back to 1200 A.D. In fact, Engineers had considerable experience designing them into drives transmitting greater horsepower than those used in the early belt conveyors. In belt conveyor application, a pulley's purpose is primarily three-fold, 1) support the belt in directional changes, as designed in the conveyor, 2) transmit driving power to the belt, and 3) guide or train the belt. There are various types of pulleys used in belt conveyor systems and these are thoroughly covered in "Belt Conveyors For Bulk Materials" prepared by CEMA, 1966. For our discussion, however, the most common used in belt conveyors are drive pulleys, snub pulleys, head pulleys, tail pulleys, takeup pulleys and bend pulleys. The drive pulley imparts the driving force to the belt and may be located at the head or discharge end of the conveyor, in return strand, or at the tailor loading end of the conveyor. A snub pulley is located near the drive pulley to provide more arc of contact between the belt and pulley for maximum

Jan 1, 1971

By K. W. Lentz

The Maybell Mill of, Trace Elements Corporation, Unit of Union Carbide Corporation is located approximately five miles northeast of Maybell, Colorado, and twenty-five miles northwest of Craig. It is located in the midst of the uranium ore deposits whose presence, made it possible. In November 1953 Russel Cutter, Chief Geologist for the original Trace Elements Corporation, picked up high readings on a scintillometer while flying over this area. Later, with George Morehouse, Chief Engineer for the original. Trace Elements Corporation, he started a search for surface indications. In this search, they found an out crop which can be regarded as the discovery lode on this property. The actual locating of claims and acquiring free lands and state lands was begun in March 1954. During 1955 enough drilling was done to indicate that a sufficient tonnage of ore existed to make possible a mill. These ore deposits are located in the Browns Park formation which is an unconsolidated sandstone with a few hard lime ribs running through it. The geologists tell us that this region was once a vast basin which became filled with wind blown sand and volcanic tuff, Later on, ground waters brought uranium into the basin which precipitated out in the sand. During the late summer and fall of 1955, a small pilot plant was operated under the supervision of John L. Chapman testing these Browns Park ores. During the operation of the pilot plant, three small open pits were developed and the ore from these pits shipped to Union Carbide Nuclear Company, Division of Union Carbide Corporation, at Rifle. To date all ore is being mined from open ptis. In the fall of 1956 the original Trace Elements group signed a contract with: the AEC for a mill at Maybell and on November 5, 1956, Union Carbide acquired the Trace Elements Corporation properties and contract. During the next two months, intensive research was carried out on the Browns Park ores by our research lab at Rifle. They also checked some of the metallurgical results which had been obtained through the operation of the pilot plant by the original Trace Elements group. During this period, a report on Trace Elements Corporation ores was also prepared by the Colorado School of Mines Research Foundation. This report contained data on representative samples of the ore tested for the original Trace Elements group. From this research and study a flow sheet was decided upon.

Jan 1, 1959

By F. J. Susko

The Bureau of Mines applied a flotation model to the hydrodynamics of the Bureau-developed rapid flotation system. Rapid flotation is a process which separates the bubble-particle attachment and froth-pulp separation stages of the flotation sequence into two discrete unit operations allowing the operations to be individually optimized. Both an air-injected hydrocyclone and an in-line mixer were used as the bubble-particle attachment unit and a shallow-depth froth separator was used to separate the ore-laden froth from the pulp. A 10-L/min batch system was tested on a coarse coal feed sample. The system was tested using two different bubble-particle attachment units at various aeration levels in order to test the flotation model. The results of the flotation model reflect general trends observed in the experimental data.

Jan 1, 1993

By John A. Dearinger, Fred D. Wright, Robert C. Howell

INTRODUCTION The rock mechanics study of the shortwall mining system at Beth-Elkhorn corporation's Hendrix No. 22 Mine is being conducted under contract with the U.S. Bureau of Mines. The objective of the study is to obtain data on surface subsidence over a portion of the mined area, strata subsidence in the mined area, and underground stress changes and displacements in and near natural support elements of the mining system. This study is currently in progress, and only a portion of the results are being presented at this time. The Hendrix No. 22 Mine is located in the moderately rough mountainous terrain of Letcher County in eastern Kentucky. The nearest mine workings to the shortwall area are approximately 1,900 feet distant. The depth of cover over the mined shortwall area varies from 770 feet at Panel 1 to 170 feet at Panel 5 (Figure 1). The strata in the shortwall area is summarized in the three core logs shown in Figure 2. Hole no. 2 is located in approximately the center of the mined shortwall area (Panel 3, Line C, Figure 1). The coal seam in the shortwall area is approximately 4 feet thick and horizontal, although one major ‘roll’ intersects all panels.

Jan 1, 1977

By Christopher R. Winter

Mining companies have sharpened their refocus on their tailings management strategies in recent years. Mining companies with tailings storage facilities that use the upstream construction method have been challenged to track the evolution of industry standards, assess risks, revise design, and communicate design revisions with regulators. While many aspects of best practices and industry standards have evolved in recent years as an attribute of continual improvement, the controlling standard in the design of many upstream dams is understanding the foundational strengths of hydraulically deposited tailings. Following best practices and industry standards, Hibbing Taconite Company managed by Cleveland-Cliffs, began the re-evaluation of foundation strengths underlying a system of upstream dams at the company’s iron ore mine tailings storage facility in northern Minnesota. Initial steps in the re-evaluation require reanalysis of design parameters and recommendations by the Engineer of Record to the Owner, which was followed by a series of meetings with the Technical Review Board to determine an initial path forward. Once a path forward and preliminary design parameters were determined, the Owner engaged with the State Dam Safety Engineer to discuss and seek approval of the plan. With continuous regulatory engagement throughout the process, further refinement of the design parameters for the hydraulically-placed tailings foundations underlying upstream dams began with field and lab geotechnical investigations. Following a review of risk assessments and trigger actions response plans, Hibbing Taconite revised its tailings storage facility operating plans and budget for the coming years. Based on the findings of the re-evaluation, reanalysis, and refinement of parameters, a paradigm shift was realized with the hydraulically placed tailings foundation strengths underlying the upstream system of dams. This paper explores the path that the Hibbing Taconite Company followed to understand the paradigm shift and construct downstream improvements. The plan involved tailings re-characterization, dam design revisions, operating plan reconciliation, budget revisions, wetland permitting, dam safety permit amendments, storm water prevention plans, borrow materials studies, new concrete decant structures and the pursuit to recognize and be consistent with industry standards.

Feb 1, 2024

By Mark R. Rybak, James Delmonte, Travis Hartman

The City of Phoenix, Arizona designed a 7.2 km (4.5 mi) long water transmission main from the South Mountain Reservoir to the Ahwatukee Foothills Reservoir to address the growing demand for drinking water in the southeast valley. The pipeline design called for a bored tunnel in a very environmentally sensitive area. The Reach3B contract included an 2.44 m (8 ft) diameter TBM excavated tunnel, 1,847 m(6,060 ft) in length. The geotechnical investigation revealed that the tunnel would likely pass through zones of loose to moderately cemented soils (caliche). The primary tunnel support would consist of rock bolts, circular steel ribs, hard wood lagging, and mine straps. A TBM that could handle the ground conditions and allow for efficient ground support installation was required. This paper describes the construction of a small diameter rock tunnel in challenging ground conditions.

Jan 1, 2003

Reaction kinetics for gold dissolution in acid thiourea solutions were investigated using formamidine disulfide as an oxidant. For the conditions studied it appears that a surface reaction limits the rate of gold dissolution. The rate was found to be first order with respect to thiourea concentration and half order with respect to the concentration of formamidine disulfide; the apparent activation energy for the reaction was 10.40 kcal/mol (43.40 kJ/mol); and the reaction rate was independent of pH for the pH range 1.0 to 3.0.

Jan 1, 1999

By L. S. Gertsch, M. Z. Abu Bakar

Linear cutting tests of a porous sandstone with a radial drag pick show that saturation of rock with water can increase the specific energy of fragmentation. This appears to be due, in this case, to a saturation-induced increase in the forces acting on the cutting tool without a concomitant increase of the fragmented volume. The mechanisms of this reaction are explored by examining various responses of the parameters controlled and induced during the linear cutting tests, such as cut spacing, cutter penetration, three-dimensional forces and muck production. A program of load-indentation testing is underway to evaluate the permeability threshold of this behavior. These findings are opposite from those made when the same rock is cut with a constant cross-section disc cutter reported elsewhere (Abu Bakar and Gertsch, 2011). Such results highlight the effects of different cutting tool designs, and indicate the need for a well-coordinated program of research to support effective excavator design and selection.

Jan 1, 2012

By W. A. Crosby

All mine operators using explosives want to maximize explosive performance while minimizing blasting costs. Use of bulk explosive products such as AN/FO, heavy AN/FO, slurries and emulsions has greatly improved blasting efficiency over the years. Many operators have improved energy output from these products by adding aluminum. A major problem facing them is the fluctuation in aluminum price. The question therefore becomes, when is it economically advantageous to use aluminum in bulk products? This paper answers this question by first reviewing the energy output from the main types of aluminized and non aluminized bulk mixed explosives and then by showing the relationship between the different products on a cost and energy basis. The paper finally presents examples of charts and tables which will aid mine operators to conveniently select the most economically correct bulk explosive, including the level of aluminum addition.

Jan 1, 1991

By George A. Roche

Since our firm was established by Mr. Price in 1937, we have followed an investment philosophy which is based on the belief that investment in growth stocks is the most assured way of achieving superior, long term investment accomplishment. There are many criteria that we use to select growth companies but the most important is a combination of superior management operating in an industry with above average growth potential. This growth stock approach is the cornerstone of our investment strategy for two of the three mutual funds sponsored by the Price organization and for our private clients. However, during the past 5 years we have seen inflation accelerate due to a variety of factors including the inability of our government to meet seemingly unlimited needs with limited revenue sources. While there might be temporary periods of price stability, we believe that inflation will still continue to be the investor's greatest problem in future years. Our conviction that inflation would increase combined with the acceleration of inflation in the late 1960s stimulated an intensive investment research effort, on our part, to identify those companies with strong natural resource bases -- who own or control large, secure, and low cost tangible assets. Over the longer term and in an environment of a depreciating dollar some of these firms should be able to develop and sell these assets at higher prices. While we still believe that investing in growth companies is a sound investment strategy to offset inflation, we also believe that certain natural resource companies will show well above average investment performance. In the newest Price mutual fund, The Rowe Price New Era Fund, we have, as a matter of policy, placed a large portion of the portfolio in natural resource companies.

Jan 1, 1972