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By J. Yianatos

The collection zone residence time distribution (RTD) of mechanical self-aerated flotation cells was characterized for liquid and solid per size class (-45 mm, +45-150 mm and +150 mm). It was found that a single large industrial cell with a volume of 130 to 250 m3, now used in plant operations, can be well represented by an LTST (large and small tank-in-series) model plus dead time. From a scale-up point of view, results showed a similar mixing behavior for industrial cells ranging from 130 to 250 m3. Also, single mechanical cells showed a similar mixing pattern (RTD) when compared to large pneumatic flotation columns. It was confirmed that for practical purposes, the mixing condition in a flotation bank of three or more cells in series can be well described by the classical N tanks-in-series model.

Jan 1, 2008

By Yi Luo

Bolting the mine roof is one of the noisiest underground mining operations. The main contribution to the noise is the drilling of the roof bolt holes, especially drilling in hard rock. Previous research shows that the specific energy consumed in drilling bolt holes is inversely proportional to the bite depth (i.e., penetration per drill revolution). Less specific energy at a reasonably high bite depth means less energy is wasted in the drilling process for producing heat, bit wear and noise. Therefore, proper control of the drilling operation to achieve a reasonably higher bite depth can reduce drilling noise from its sources as a proactive noise control approach. In order to explore the feasibility and develop the proactive technology for reducing drilling noise, drilling tests have been conducted in laboratory settings. The preliminary results show that significant reduction in noise dose can be achieved by drilling in medium hard rock with uniaxial compressive strength of about 276 bars (4,000 psi) and at a reasonably high bite depth of about 4.6 mm/rev (0.18 in./rev). This paper presents the findings from laboratory experimental studies.

By Georgene Renner, Chee Theng, William Gleason

"In February 2018, drawn in part by the states’ proud mining heritage, SME took its Annual Conference & Expo to Minneapolis, MN for the first time. More than 5,000 people and 554 exhibitors converged on the Minneapolis Convention Center for three days of networking, exhibiting and technical sessions.The state’s mining legacy, one that continues today, is fueled in large part by its vast iron ore resources in the northern part of the state. The historical significance of the mines in the Mesabi Range, otherwise known as the Iron Range north of Lake Superior, cannot be understated. “Mining is a way of life here,” said U.S. Congressman Rick Nolan of Minnesota’s 8th Congressional District. A native of the Iron Range, the three-term U.S. congressman was one of the featured speakers of the opening keynote session. “We like to think we contribute enormously to the well-being of this country and the world. We were the source of the iron ore and steel that helped win two world wars. And we like to think that we are part of the progress that has taken place in the United States ever since.” Nolan kicked off the keynote sessionthat focused on innovation and its part in the mining industry. The session included Rene Aquilar, vice president of corporate affairs and sustainability, Antofagasta Minerals Group; Bob Anderson, vice president for research and development, 3M; Rolf Weberg, executive director, Natural Resources Research Institute, University of Minnesota-Duluth and Christopher Beck, executive vice president and president, Nalco Water. The panel session looked at U.S. and global minerals production, and the importance of the United States to maintain a major role in the minerals industry, both as a producer and as a technology leader. The panel also touched on the global mining industry and the issues that impact mining around the world. Sustainability, the use of water in mining and earning a social license to operate were among the topics discussed by the panel.Speaking of the importance of mining, Nolan conceded that talking about the benefits of mining to the crowded auditorium at the SME conference might be akin to a preacher speaking to the choir, but, following the adage that all politics are local, he continued to illustrate his point by emphasizing the importance of mining to the Great Lakes.“A study by Homeland Security concluded that 13 percent of the nation’s GDP comes out of Lake Superior through the locks at Sault Ste. Marie and most of that is iron ore,” said Nolan. “That study found that, if those locks fail, it would create a national depression. It would put millions of people out of work. That ore and those minerals supply the steel mills, the auto industry, the heavy industrials. They are the heart of our economy. The study concluded that if the states that make up the Great Lakes were a nation, it would be the fourth largest economy in the world.”"

Jan 5, 2018

By Euclid P. Worden

INTRODUCTION Today, conventional raise boring is an accepted method of development in underground mines and on major construction projects. Over the years that this technique, and its associated machines and tools, have been under development, many articles have been written on the subject. To a great extent, these papers have reported operating results of one or more specific projects or have been generalized reviews of state-of-the-art machines and tools. This paper is intended as a review of the technique from an operational standpoint. Conventional raise boring, as opposed to the related variants box hole drilling and underground blast hole drilling, is a two step process consisting of the pilot hole drilling and reaming cycles. This author has covered the subject of pilot hole drilling in another article (1) . A good review of the current machines and equipment has been presented by Monroe (2) and an overall review of this entire technology was published by E&MJ (3) and Mining Journal, April, 1983 (4) . The subject of the reaming cycle is presented here together with some of the technical aspects of how the drilling tools are intended to be used. OPERATIONS Bit Change After the pilot bit has broken through at the end of the pilot hole cycle, a changeover takes place at both the machine and

Jan 1, 1985

By Franco Oboni, Iain G. Bruce

The design of tailings containment structures relies on well-understood engineering methods being applied consistently. Unfortunately, not all facilities are designed or managed to the same level of competency. To standardize procedures, the Mining Association of Canada (MAC, 1998) prepared a “Guide to Tailings Management.” It recommended review of designs and an assessment of the risks associated with tailings impoundments be implemented during all phases of amine life. This paper describes how the quantitative risk assessment (QRA) process can be used to define risks associated with the design, construction and operation of a tailings management facility. And it discusses how, once the risk tolerability curves (RTC) are defined for a project, they can assist the risk management (RM) process.

Jan 1, 2002

By Rodger C. Fry

Underground coal mining has been active within the East Mountain property since the mid 1950's. As a result, coal from two seams has been extracted within large areas allowing surface subsidence to occur. Monitoring of subsidence annually, began in 1981 using on the ground conventional monumentation, surveying and photogrammetric monitoring. The data collected has shown the time benefits of photogrammetry and the relationship between observed subsidence and the geometry of the mined out area below.

Jan 1, 1986

By William G. Fischer

This paper attempts to close the gap between extensive rock testing with field measurements and the mine operator's need for safe mine layouts and alternatives. It was found that many of the variables that influence mine geometry and worker safety are relatively unimportant while others are critical. The development of empirical relationships which tie the critical variables to the "safe useful life" of a trona mine layout and observations made in 140 production areas where the variables were researched over a fifteen year period are discussed. The concepts presented may have applicability in mine design for other bedded deposits.

Jan 1, 1984

By Dexter C. Hatch

At MacIntyre Development of the National Lead Company, Taha s, New York,, the flotation plant was set up to recover ilmenite from the finer size fraction of the ore that cannot be efficiently treated in the main gravity-magnetic separa¬tion process. It was later expanded to handle the reground middlings from the tables wetherill magnetic separators. The ilmenite-magnetite ore is ground to minus 20 mesh in five 6 x 12 ft. rod mills in closed circuit with DSM screens. The minus 20 mesh screen undersize is pumped to four parallel sections each consisting of two rougher wet-magnetic separators and one cleaner separator for magnatite removal. The screen undersize from the fifth section is distributed to all four sections. The magnetite removed in the roughers is pumped back to the cleaners and the cleaner magnetite is dewatered in rake classifiers and carried by belt to the winter plant or the stockpile area. The nonmagnetic sands from rougher and cleaner magnetic separator are sized for table feed in eight pocket hydraulic sizers. The slime overflows from the Crocketts, the sizers, and the magnetite rakes are collected and pumped to three-inch cyclones for thickening and desliming. The cyclone underflow is the principal flotation plant feed.

Jan 1, 1962

By Terry R. Guilinger

A minitest of the new potassium chloride-potassium carbonate two-stage in situ uranium leach process has been carried out at the Intercontinental Energy Corporation (IEC) Zamzow project site in South Texas. Substantial quantities of high concentration uranium were produced indicating the viability of the leach solution. The test results yield information regarding the reservoir dispersivity, the average cation-exchange capacity of the formation, and the distribution coefficients describing carion-exchange reactions. The test a1 so indicates permeability anisotropy and the existence of disturbed flow fields. The research was partially funded by the U.S. Bureau of Mines.

Jan 1, 1984

By Staff

Minerals contribute to U.S. gross domestic product (GDP) at several levels - from mining and processing to the manufacturing of finished products. In 2010, the estimated real GDP of the United States increased by 2.8 percent compared with 2009 and the estimated nominal GDP was about $14.6 trillion (Table 1).Trends in various sectors of the domestic economy are often rejected in mineral production and consumption rates. For instance, continued declines in the construction industry during 2010 were rejected in further reductions in the production and consumption of cement, construction sand and gravel, crushed stone and gypsum, which are used almost exclusively in construction. Performances in other sectors were mixed and less easily characterized. Recovery from the economic decline of 2008-2009 became apparent in 2010, as prices for many mineral commodities continued to rise with increasing demand for those materials or the products in which they are found.

Jan 1, 2011

By V. B. Achanti, A. W. Khair

Laboratory studies were carried out at West Virginia University to investigate the rock fragmentation mechanism by continuous miners using an automated rotary cutting simulator. The primary factors influencing the fragmentation process were found to be: bit spacing, bit geometry, depth of cut and cutting drum rotational speed. This paper presents the influence of these parameters in achieving optimum energy consumption and minimizing dust generation during rock fragmentation process. Tree bits were used simultaneously on Indiana limestone while the bit tip angle was varied from 60° to 900. Bit spacing was varied from 2.54 cm (1 in.) to 5.08 cm (2 in.) while the cutting process was assessed for varying cutting depths. Restorable dust generated during the course of the experiments was analyzed utilizing cascade impactors. Assessment of these parameters has led to a better understanding of the cutting mechanism by continuous miners in terms of energy consumption and dust generation.

Feb 24, 1997

By M. I. Brittan

Cyanide leaching of two West African gold ores was studied in multiple laboratories to provide process-engineering data for plant design purposes. Unusually slow leach extraction kinetics were observed using routine cyanide leach test procedures with pregnant solution monitoring. Carbon-in-leach testing, however, showed normal rapid kinetic behavior, with the same ultimate gold extractions being reached in much shorter elapsed times. Kinetic curves based on washed solids assays also exhibited more typical leaching characteristics. The results bore all the hallmarks of some equilibrium inhibition of the leaching. It was surmised that ore gangue components were responsible for weakly adsorbing gold-cyanide complex reaction product, thereby holding up soluble gold in the solid phase. The term ?preg-borrowing? was coined to describe the reversible phenomenon and distinguish it from irreversible preg-robbing. The two ores investigated may represent an extreme form of a more general effect that in most instances might pass unnoticed. The effect can lead to misinterpretation of kinetic leach curve data and underestimation of calculated ore head grades.

Jan 1, 2008

By SME SME

NORTH AMERICAN TUNNELING 2024 PROCEEDINGS

Jun 23, 2024

By Joseph Kuti

Longwall mining is the term used for the underground extraction of a wide and deep panel of coal. Such a panel may be blocked out by one or more entries on either side ("head" and "tail") of a longwall face. If all the entries are pre-driven, the panel extraction is termed longwall retreat mining. With one exception, all the longwall faces in the United States are of this type. (1) prior to the general decline in the rates of production with Continuous Miners, the development of the multiple entries generally kept ahead of the longwall extraction rate. This is no longer the case: longwall extraction rates far exceed the rate of development. In addition to this problem, in newly established mines, the development of a haulage and bleeder system based on multiple entries results in a lead-time of three years or more before longwall mining can be applied. This is one reason why earlier projections and much of the optimism attached to longwall mining as a principal "savior" in the energy crisis should be viewed with some caution.

Jan 1, 1978

On June 4, Kennecott Utah Copper (KUC)marked the centennial of the founding of the original company. Bill Champion is president and chief executive officer of KUC. He said, “What has happened during the past 100 years far surpassed even the most optimistic visions of men like Daniel C. Jackling and Robert Gemmell when they promoted the concept of mass production techniques for a low-grade deposit of copper ore. At that time, it was a totally new way of doing things and the mining leaders of that day scoffed at the idea. They said it would never work,” Champion said. The company will celebrate this once-in-a-lifetime occasion with a few special projects, mainly for the benefit of our employees, said Louie Cononelos, director of government and public affairs for KUC. The company has designed and minted a commemorative copper coin that reflects early steam shovel and locomotive operations on one side, and today’s modern electric shovels and huge haulage trucks on the other side. “The history of the company stems from the ores of the Bingham Canyon Mine. That coin has been encased as part of a10-panel brochure that captures the company’s 100 year history,” he said. KUC also developed special centennial banners and comparable framed posters that were displayed throughout its operations and at selected community locations that have enjoyed a long-time partnership and special relationship with the company. Some of the plants also designed their own centennial hardhat decals.

Jan 1, 2003

By Taghi Sherizadeh, Kutay E. Karadeniz, Dogukan Guner, Samuel Nowak

Seals and build-in-place (BIP) refuge alternatives (RAs) are two main underground structures to isolate an area from the active working zones with different purposes. While seals are used to prevent methane gas that seeps from coal seams and blast pressures from a possible detonation of the contained gas, RAs are used to provide a safe haven for miners who are unable to escape their working locations after an accident like an explosion or fire. The recommended BIP RA designs can be similar to seals constructed with steel-reinforced concrete. Both seal and BIP RA are constructed in different locations of the mines for a period of time, exposed to a certain convergence due to stress redistribution which can change their responses during an explosion. In this study, a steel-reinforced concrete wall to be used in such applications is simulated to examine the structural performance during an explosion for a coal mine model with different strata conditions using dynamic analysis by a 3D distinct element method (DEM) code. The main purpose of this study is to reveal any possible effects or trends on the wall deformation with changes in strata conditions by implementing different combinations of roof, seam, and floor material properties. The model is calibrated by the experiment conducted on a steel-reinforced concrete wall by the NIOSH researchers in the Lake Lynn Experimental Mine. The results show that strong adjacent rock and coal units are the least favorable condition for the survival of the wall subjected to a simulated explosion pressure. The results indicate that changes in the roof and seam conditions can have dramatic effects on the deformation characteristics of the wall when compared to the floor conditions. The results of this study might be enlightening for future BIP RA and seal applications.

Feb 8, 2023

By Robert F. Shurtz

This paper suggests that pre-occupation with the random process model notised by geostatisticians may result in neglect of more promising techniques, especially since the random process model does not appear to be essential to current geostatistical procedures. This point of view is emphasized pictorially. To emphasize the potential of new techniques a simple application of the conventional Brownian function is described. The probabilities estimated in this truly random way are different from those estimated by Kriging

Jan 1, 1980

By J. N. Van der Merwe

The paper provides an overview of subsidence research which was done by the Sasol Company in South Africa over a period of more than six years. The magnitudes of subsidence elements in South Africa are largely similar to those in the U.S.A. and Australia, as opposed to Europe. The research resulted in a subsidence prediction method with a new approach to the prediction of ground strain. The paper also describes the effects of subsidence on various commonly occurring surface structures such as roads, overland conveyor belts, pipe lines and power pylons. It is concluded that while most structures are not specifically designed to accommodate mining induced displacements, they can nontheless be undermined safely and economically with only minor precautions.

Jan 1, 1986

By Samer Sadek, Brian Hagan

We are thrilled to welcome you to the 2025 Rapid Excavation and Tunneling Conference (RETC), which will be held in Dallas, TX. This year’s conference will showcase the continued trend of strong industry interest, as there will be a record setting 115 papers being presented over the course of three days. The set of papers compiled in this book captures the latest and greatest information on a broad array of topics within our fascinating tunneling industry. We hope that the compilation of selected papers in this book will provide a comprehensive recap of the conference while also providing a source of future reference for contractors, engineers, and anyone in general who is a student of our beloved and unique industry. Since its inception in 1972, RETC has been the preeminent tunneling forum to promote ideas, tell stories, share lessons learned, and promote new technologies. RETC prides itself on its focus towards highlighting real-world experiences and practical ideas, with the intent to help the entire industry learn from one another and grow. The need for us all to stay sharp and remain on the cutting edge of technology has never been stronger – the technology and ideas that have been applied in aerospace are now attempting to mix with tunneling, and the advancement of AI continues to permeate all industries. However, no amount of technology or AI can fully replace the human element, and in our tunneling industry, the human element is key and is what sets us apart. In tunneling, every project is different, because the ground is always different. We can only take what the ground will give us, and we must rely on our past experiences to get through present day challenges. Most importantly, we must rely on each other. This is the heart of what RETC is all about. For those of you attending this conference, we encourage you to attend as many sessions as possible and engage with your colleagues to discuss during the breaks in between sessions. This sharing of ideas is what keeps us connected and helps to expand our industry. Please also try to engage with the scholarship students and the newcomers who will be in attendance, as it is the new ideas and fresh energy from the next generation that will continue to make our industry thrive into the future. The program chairs thank and greatly appreciate the efforts made by our session chairs, co-chairs, authors, the members of the RETC Executive Committee, and most importantly the SME staff towards making this RETC possible.

Oct 1, 2025

By A. Eccles

Phase designs are the foundation upon which all open pit mine sequence optimizations and budgets should be built. Unfortunately, at times, mine engineers skip the step of developing realistic pit phase designs - designs that include access ramps and mineable widths. Without mineable phase designs, their optimized schedules are based on theoretical pit shells or ?quick-and-dirty? plans with no ramps. The output from such optimizations is almost always overly optimistic. Without mineable designs, the production estimates are misleading, because they overestimate ore, and underestimate waste stripping requirements. Worse yet, when plans are not based on realistic phase designs, they can point to exactly the wrong decision in feasibility studies (i.e. ?go? when it should be ?no-go?). This paper discusses the importance and features of good pit phase design, and demonstrates the pitfalls of relying on optimized production sequences that are not based on properly designed pit phases.

Feb 27, 2013