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By J. F. Stenebråten, W. P. Johnson

Carbonaceous material (CM) from the Barrick Goldstrike Mines, NV, was characterized with respect to its gold sorption (preg-robbing) and gold recovery behavior. The breadth of graphite peaks measured by X-ray diffraction were used to calculate crystallite dimensions (002) of the CM. The (002) dimension was found to vary inversely with preg-robbing activity and directly with gold-recovery behavior, indicating that the degree of graphitization (maturation) experienced by the carbonaceous material is correlated with gold-loss during ore processing. The inverse correlation of preg-robbing activity was improved when percent preg-robbing was regressed against (002) crystallite size and carbon content. The (101) crystallite dimensions of all samples were calculated from laser Raman analysis, and were not found to correlate with preg-robbing behavior of the CM. BET surface area and micropore size distribution results were affected by grinding history, negating comparison of these characteristics between samples.

Jan 1, 2000

By Lawrence K. Nordell

Historical methods of designing steel cord belt splices are compared with modern finite element modeling (FEM) methods. Dependence of the belt strength rating on the splice dynamic fatigue strengths is reviewed. A number of splice schematics are examined, using simple spring theory and FEM methods. Steel cord wire rope design is discussed. The importance of the insulation gum rubber properties and their splice dimensional factors and tolerances are analyzed. Splice fatigue lie analysis procedure is reviewed. This may be used to predict splice life or time of failure, depending on how the conveyor belt is operated.

Jan 1, 1993

By W. Clark Ashby

Productivity is a fascinating concept. Like motherhood or apple pie, we know it as a good thing. Just what it means is not so clear. To a coal miner we assume it means tons of coal hauled from the mine. To the company president it means profit after capital, labor, and other costs have also been reckoned. To the government economist it means output in a balance of payments. What does it mean to the biologist, and can reclamation really be productive? In this paper we discuss productivity from a biological viewpoint, give some yield data for various types of reclamation plantings, and discuss how our demand for or acceptance of differing kinds of productivity is tied up in bigger questions of land use, environmental stability, and resource allocation.

Jan 1, 1981

By Drew Bazil, David Smith, Matteo Ferrucci, David Pittman

The Gateway program will provide additional rail capacity between New Jersey and Manhattan. This paper describes how a 70-foot-deep section of cut and cover tunnel was designed to directly support future high-rise towers. The tunnel will link previously completed tunnel sections under Hudson Yards to future tunnels under the Hudson River. The design aims to minimize constraints on future overbuild and future tunnels, while maximizing constructability within a small worksite. The tunnel will pass under the High Line elevated walkway, next to an active rail yard, and close to a subway tunnel. The design was developed by a tri-venture of WSP, STV and AECOM. WSP led the design of major underground works; STV designed utility relocations and the underpinning concept for the High Line; and AECOM designed temporary in-tunnel systems. Construction is expected to start in 2023.

Jun 13, 2023

By R. J. McGregor, Deepak Malhotra

Engineers frequently encounter situations where decisions that are counterintuitive to the logically trained engineering mind are made because of other influences, whether they be financial, social, cultural, or environmental. Such influences can overrule the "logical" decision-making process. The aim of this book is to explore some of the nontechnical issues, which most engineers don't learn about in school, that can have a major impact in the mining industry. This chapter gives a brief overview of this volume and introduces the topics that will be addressed.

Jan 1, 2001

By C. I. Wilmot

The paper presents an update of the Paradise Peak mill after the first year of operation. Process revisions, equipment modifications and additions, and personnel requirements are discussed with a comparison to original design. All areas of milling are discussed including crushing, grinding, leach/countercurrent decantation (CCD), precipitation, refinery, and heap leach.

Jan 1, 1987

By Stephen Slot Odgaard, Simon D. Taylor

Phase One of Copenhagen Metro opened on October 19th, 2002 and is already a great success. 11 stations are open and Phase Two with 6 additional stations will open during 2003. Phases One and Two include 21 km dual track, whereof 10 km is in tunnel. 17 stations (six deep, three shallow, and eight above ground) will service passengers with trains running at 90 seconds intervals. This paper will discuss the various aspects of the Metro, where construction methods include TBM bored, NATM, Cut & Cover, Secant Piles and Diaphragm Walls.

Jan 1, 2003

By Michael Schmalzel

Freeport-McMoRan Copper & Gold, Inc. (FMI) will soon begin copper production from the Dos Pobres and San Juan deposits near Safford, Arizona. Ore reserves total 615 M tons grading 0.36% copper, predominantly as chrysocolla. Copper extraction will be by leaching with sulfuric acid. Fluor Canada Ltd. provided EPCM services to design an ore handling and conventional SWEW facility capable of producing a nominal 240 million pounds per year of cathode copper. The ore handling facility will process 114,000 tons per day of ore through three-stage, open-circuit crushing followed by agglomeration and product placement on the permanent leach pad. Stacking of ore on the leach pad will utilize Terra Nova Technologies' "Super Portable" mobile stacking system. The stacking system fleet consists of 13 self- propelled, crawler-mounted mobile conveyor units, each with 72-inch-wide belting and a capacity of 6,800 tons per hour, including ten 250-foot-long portable conveyors, a horizontal feed conveyor, a 285-foot-long horizontal conveyor and a 220-foot-long radial stacker. PROJECT BACKGROUND Project History The Safford Leach Project is located in the Safford mining district in Graham County, Arizona, approximately eight miles northeast of the town of Safford and 170 miles east of Phoenix. The 3,360-acre property is located in the Gila River Valley, immediately south of the Gila Mountains, at elevations between approximately 3,000 and 5,400 feet above sea level. The Safford Leach Project is comprised of the Dos Pobres and San Juan deposits, two of five known copper ore deposits in the Safford mining district.

Jan 1, 2008

By Madan M. Singh

It is estimated that through 1975, there were 1.69x109 m2 (418 000 acres) of urban land threatened by potential subsidence due to mining with a value of over $12 billion (19;3 dollars; USBM, 1979). With increased coal production to meet the energy needs of the nation, both these figures may be expected to increase. Hence greater attention to controlling surface damage due to subsidence is merited. In fact, the Surface `lining Control and Reclamation Act of 1977 (SMCRA) (Public Law 95-87) mandates that underground coal mining operators "adopt measures consistent with known technology in order to prevent subsidence causing material damage to the extent technologically and economically feasible, maximize mine stability, and maintain the value and reasonably foreseeable use of such surface lands, ..." The term "subsidence," as used in this paper, implies the total phenomenon of surface effects associated with the mining of minerals, and not only vertical displacement of the surface as is sometimes inferred in the literature.

Jan 1, 1984

By Victor Despointes, Stephane Polycarpe, Kathryn Kelly, Chris Feeney, Brian Hann, Vojtech Ernst Gall

The Pawtucket Tunnel is a 2.2-mi, 30.2-ft diameter CSO storage tunnel in Rhode Island. The primary tunnel is built using a dual-mode open-EPB TBM capable of sealing the face within 120 seconds to manage poor ground and water ingress which is launched from within a SEM starter tunnel. The main tunnel connects to four adits along its alignment, three of which are SEM tunnels and one being a MTBM tunnel. This contribution describes the selection process, potential risks, and requirements for the TBM, as well as the design of the main tunnel, the adits, and the adit-bored tunnel connections.

Jun 13, 2023

By Michael Fahey, Ravi M. Damodaran, Brij M. Moudgil

The flotation behavior of Florida phosphates was studied using statistical design of experiments to evaluate conditioning parameters and their effect on flotation performance. The solids loading, conditioning time and agitation speed during conditioning were identified as the important variables affecting the reagent coating onto particles. Flotation of the conditioned slurry was carried out at fixed collector dosage and flotation conditions. Phosphate recovery upon flotation was statistically modelled as a function of the conditioning variables. The results indicated that the conditioning variables had an interactive effect on the phosphate flotation performance. Statistical optimization revealed two conditioning regimes in which optimum flotation recovery was obtained. It was determined that optimal recovery can be obtained at lower conditioning energies.

Jan 1, 1995

By Slobodan Vujic, Goran Cirovic, Dragan Radojevic

Mine production systems (MPS) are characterized, more or less, by the following properties: uncertainty, subjectivity, impreciseness, polysemy, instability, indefiniteness and lack of data. From modern study aspect these MPS mathematically belong to the class of fuzzy systems. With this in mind, the usage of fuzzy sets is recommended as a methodology that treats impreciseness, indefiniteness and complexity of mine production systems in a satisfactory manner. Fuzzy modelling, discussed in this pa- per, is applied as a mathematical implement. The objective of the paper was to show production optimization in practice on the ex- ample of bauxite open pits where fuzzy linear programming (FLP) was used following the criterion per income. The variables in criterion function are linguistic variables while both variables and variable restrictions are presented by triangular fuzzy numbers (TFN). The term "satisfactory income" presented through triangle fuzzy numbers was introduced instead of "maximizing the income". sensitivity of the obtained solutions has been analysed

Jan 1, 1996

By James K. Kindig

Hazen Research, Inc., has developed a new process for removing pyritic sulfur and ash from coal. Feed coal is contacted with iron carbonyl vapors, Fe(CO)5, at 190°C which puts a thin skin of magnetic material on the pyrite and ash, but does not affect the coal. Thus, low intensity magnetic separators yield a nonmagnetic coal, low in sulfur and ash, and a magnetic refuse, high in sulfur and ash. Results are given for clean coal produced by this method. A comparison is made between results of the magnetic process and the U. S. Bureau of Mines two-stage flotation process cleaning identical samples of Pittsburgh Coal. Capital and operating costs of the two cleaning methods are discussed.

Jan 1, 1976

By D. S. Choi, H. D. Dahl, D. L. McCain

The paper examines current room and pillar mining practice in the U.S.A. from the standpoint of rock mechanics. Consideration is given to the deformation characteristics of the roof formation and the coal seam as determined in the laboratory as well as in the field. The results can be utilized by the practicing mining engineer to improve current mine design practice.

Jan 1, 1982

Diesel engines are used in underground mining 1 throughout the world. Exhaust gases from those engines contain toxic components. To protect quality in underground mines, diesel emission control was introduced decades ago, many years before the first surface applications. Today, emission controls, such as catalytic converters, are standard on underground diesel engines in countries concerned with occupational safety and health. Nett Technologies manufactures a range of diesel emission-control devices for underground mining. Emission problems are not the same at each mining operation. And there is no universal control technology. The selection of exhaust aftertreatment technology depends on raw exhaust emissions, particular emission problems, fuel quality and economics. Some of the technologies that have been used in underground mining to control diesel emissions include catalytic converters, diesel filters, fume diluters and water scrubbers. Table 1 compares the effectiveness of these technologies to control the particular components or aspects of diesel emissions.

Jan 1, 1997

By Donald E. Warnken

The Study concerns the estimation of fair market value (FMV) of non-producing mineral rights. Two approaches to value are used and the values determined by each are compared. The Study area environment is unusual. The tectonics is visible on surface rocks throughout much of the study area. The effect on mineral values in the exposed areas has been compared to areas where the tectonics is not visible.

Jan 1, 2005

By N. Edmonson

During the last 30 years, a dramatic increase in the supply of byproduct sulfur substantially reduced the share of the market held by Frasch-mined (non-by-product) sulfur in North America. Even though Canadian sulfur production is not discretionary, the geographic remoteness from the large US markets and the high transportation costs associated with delivering sulfur to those markets has meant that Canadian producers act like discretionary producers in many important ways. They have effectively replaced the US Frasch producers as the cost-marginal sulfur source to large US markets. Implications of this change in market structure include more volatile sulfur prices and longer sulfur price recessions.

Jan 1, 1998

By M. C. Stuttle

MDL Rock Lasers has undertaken successful mapping trials of abandoned mine workings using its underground cavity scanning system. The work was being performed for Kalgoorlie Consolidated Gold Mines (KCGM), Australia's largest gold producer. MDL Rock Lasers supplies underground surveying systems to the mining and quarrying industry KCGM's Fimiston Super Pit, located in Kalgoorlie, Western Australia, is Australia's largest open-pit gold operation. Fimiston's final pit design is expected to be 3.7 km (2.3 miles) long, 1.5 km (0.9-miles ) wide and 540 m (1,770 ft) deep. During the early days of Australian mining, underground operations were labor intensive. Mining was selective and generally narrow stopes were mostly backfilled. Improved processing technology and mine mechanization during the 1970s and 1980s has permitted larger scale operations to adopt less selective underground-stope operations. The "super pit" concept was a logical step for mining companies working toward economies of scale. However, the industry recognized that there was no precedent for excavating a 500-m- (1,640-ft-) deep open pit through ground previously affected by old workings. To appreciate the geotechnical challenge facing KCGM, it is necessary to consider that under the pro¬posed area at the open pit, stoping reached a level of 1 km (0.6 miles) and was supported by more than 2,000 km (1,240 miles) of development headings. The company was fortunate because plans were available for the Golden Mile underground operations. The existing plans were interpreted by the mine's geotechnical team and computer models were constructed of the underground workings. These models can be imported into three-dimensional mine planning packages, such as the Vulcan's Unix-based software, Envisage, to assist analysis and design. This prior knowledge of the workings provided the focus for investigating and confirming ground conditions using probe drilling. After several iterations of drilling, followed by detailed analysis, several decisions were made relating to the nature of the ground and the mining approach to be taken. It was recognized that the stope models were not perfect due to hu¬man error, lack of original survey information and progressive deterioration in ground conditions. It also became apparent that the sole reliance on probe drilling was inefficient in terms of time and quality of information. This was particularly true in complex areas where stopes are in close proximity. A major concern was the presence of open stopes (voids). In many cases, stopes consist of combinations of filled and void sections. The condition of pillars within these underground workings is extremely important. In time, pillars collapse and voids will propagate in upward and lateral directions. So systems needed to be developed that allowed rapid and accurate verification of ground conditions. KCGM was introduced to MDL Rock Lasers while investigating technology for underground mining. The two companies decided to use the C-ALS, MDL Rock Laser's underground laser, cavity scanning system, to improve the management of mining through affected ground. This system was to be used in conjunction with probe drilling and void mapping activities. A field test in one area of the Fimiston Mine verified the capability of the C-ALS system to quickly and efficiently assist in this decision making process. The C-ALS scanner features lightweight, carbon fi¬ber alignment rods from Measurement Devices Ltd.'s (MDL) Boretrak MKII. This is a borehole deviation system that stops the two axis measurement head rotating and lowers the system down a borehole. The scanner is deployed by a 110-mm (4.3-in.) borehole, up, down or sideways. The operator can then carry out vertical and horizontal plan section scans at any user specified ARC (an angular increment of 2°) or the distance between two points on the ARC (CHORD) increments. Windows '95 software enables the operator to control the cavity scanner remotely, surveying the area in real time. The system makes data quick and convenient.

Jan 1, 1999

By William P. Blacutt

This paper examines Bolivia's General Environmental Bill recently passed by Congress: a multi-purpose law with two primary objectives: a) the protection and conservation of the environment, and b) the promotion of sustainable development. In this law, environmental benefits are emphasized by stating general principles, not by attempting to define the means. Regulations are left to the writing of subsequent complementary codes. This paper shows that much of the controversy surrounding the legislation disappears when it is seen as guide rather than an operational part of Bolivia's industrial policy. In essence, the law addresses recent environmental awareness in a region more anxious than ever to speed economic growth.

Jan 1, 1992

By Jin Zhao, Weijie Wei, Jinwang Zhang, Xiaohang Wan, Shengli Yang

Reasonable mining-retention ratio (ratio of room width to pillar width) is vital to recovery rate and stope stability in underground mining of solid potassium salt deposits. Based on the engineering background of a solid underground potassium salt mine in Khammouan Province, characteristics of the plastic zone of the pillar, and the variation of recovery rate and stope stability under different mining-retention ratio conditions are discussed. The results show that compared with current room width (8 m) and pillar width (10 m), the optimization method of improvement of stope stability. The research results are helpful to recover as much solid potash resources as possible under the premise of ensuring the stability of stope.

Jun 25, 2024