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By K. Burke, K. L. Myers, R. Espell

Barrick Goldstrike’s (Goldstrike) AA Heap Leach Pad is an HDPE lined facility used for gold recovery from low grade ores using conventional cyanide heap leach technology, operated from 1987 through 1999. Goldstrike prepared a unique reclamation plan for the AA Leach Pad Facility to provide for a cost-effective, environmentally sound facility closure and to fulfill the State of Nevada’s closure requirements. Traditional Nevada leach pad closure has involved rinsing to reduce cyanide concentration to an acceptable level, followed by reclamation. However, certain metals and compounds are not typically reduced by rinsing and some constituents may increase in concentration with rinsing. A closure scenario to effect limited infiltration through installation of a capillary cover for the leach pad was developed. The capillary cover was constructed by placing a fine-grained layer above the coarse-grained spent leach material to create a capillary break. In an arid climate such as Nevada, the fine-grained layer will rarely reach full saturation and the cover will be able to store water during precipitation and allow removal of water through evaporation and transpiration (ET) during the growing season. A 1.22 m (4 ft) cover thickness was selected as the optimum design cover thickness. The drainage network on the surface of the re-contoured AA Heap Leach Pad was specifically designed to enhance the revegetation, reclamation, and sediment yield control aspects of the AA Heap Leach Pad closure, while resulting in a natural looking surface, compatible with the surrounding topography. Adjacent natural topographic features were used to establish target design parameters for re-contouring and erosion control design.

Jan 1, 2001

By John H. Gasper

The success of steep slope (>20°) contour mining depends on many factors. Most important is the selection of the mining method that best suits the premining site conditions environmentally and economically. These conditions can be divided into three categories: • Geometric conditions - machine limitations, slope stability restrictions, erosion capacity; • Physical conditions - material properties, rock strengths, ability to dig, driving surfaces; and • Chemical conditions - acid-base relationships, blending or selective placement of overburden. This article incorporates these conditions by conceptually modeling compliance-oriented contour mining methods, particularly haulback methods, using the combined front-end loader (FEL)/ truck, tractor/scraper, and FEL-truck and scraper. Engineering analyses, including machine selection, sequencing, ease of varying production rates, slope requirements (for stability and running surfaces) and drainage requirements can be performed after the geometric constraints dictated by in situ conditions and regulatory requirements have been conceptualized. Once all generalized geometries have been established, reduction to idealized, three-dimensional views is achieved. These are then reduced to two-dimensional symbolic models, mainly plan views but also elevations and sections. Equipment activities and operations are then conveniently overlayed. Without this simple, two-dimensional reduction, technology transfer remains awkward and non-analytical.

Jan 1, 1991

By Jose A. Delgadillo

The hydrocyclone problem has been a challenging task for the last 30 years. In the 80’s and 90’s Computational Fluid Dynamics solution to this problem began to appear. These were unsuccessful due to over simplification. In the past 3 dimensional solution with ?-e model and Reynolds Stress Model have been published. In this paper RSM and ?-e models are compared with velocity profiles measured in 75 mm and 250 mm diameter hydrocyclones. It is shown that results are not satisfactory with RSM or ?-e and that a model called Large Eddy Simulation is needed to describe velocity profile evolution and size classification.

Jan 1, 2005

By Youngtak Ko, Wonnyon Kim

Korean contract Mn-nodule field in the NE equatorial Pacific is composed of seven sectors showing average water depths of 4,513 - 5,025 m. Of the various factors controlling the property of Mn-nodules, water depth has a potential linkage to chemical composition, shape and abundance of nodules. To clarify such a possibility, we review more than 20 years of research data in one of the northern sectors (hereafter KR1) where there is a marked contrast in water depth. High-resolution seabed mapping clearly separates a northern part from a deeper southern part, cutting across the middle of the KR1. In terms of nodule occurrence, manganese nodules in the deeper north are comparatively larger (2-4 cm) with rough surface (t-type) and discoidal shape (D-type), while those in the south are generally small (<2 cm) with smooth surface (s-type) and irregular shape (Itype). In addition, the nodules in the north have higher metal contents including Cu, Mn and Ni. Such connections of water depths to nodule occurrence and metal contents are commonly observed in the Korea licensed Pacific nodule fields. However, the relation between nodule abundance, size and water depth may be a different story. In KR1, nodule abundance and size are probably controlled by morphological features especially in the north. Seamounts in the north continuously provide rock fragments as new nuclei for the nodules. As a result, the nodules can not grow larger than 2 cm and show the shapes of newly formed nodules (i.e., smooth surface and irregular shapes). Such an interpretation is supported by anomalously high backscattered intensities in the side-scan sonar image map of the north, which possibly reflects a younger generation of magmatic activity.

Sep 1, 2014

By V. Arslan

The primary advantage of using oxalic acid is in the formation during leaching of soluble complexes that are both photo-chemically and microbiologically degradable. In this study, chemical leaching and bioleaching methods were used for quartz sand. Using the ANOVA-Yates test technique, the effects of solids rate, temperature and oxalic acid rate were investigated using chemical leaching experiments. Solids rate and temperature were effective parameters on the chemical leaching. After the tests, the removal of Fe2O3 increased to 97.02%. Finally, the iron content decreased from 0.315% Fe2O3 to 0.0094% Fe2O3 in the leached quartz sand. The effect of pulp density was investigated on the bioleaching experiments. The bioleaching of iron oxides by Aspergillus niger resulted in removal of 47.70% of the total iron in the quartz sand, and suggested that this strain has not a good ability to remove iron impurities from quartz sand in comparison with chemical leaching. The iron content decreased from 0.315% Fe2O3 to 0.164% Fe2O3 in the bioleached quartz sand.

Jan 1, 2009

By M. K. Eryadin, I. Yildirim, R. Asmatulu

Novel dewatering aids were tested on various coal samples from the U.S. and Canada in laboratory and pilot-scale filtration experiments. The reagents substantially improved the dewatering kinetics and reduced the cake moistures. The cake moistures were typically reduced from 20-30% by weight to 8-14% range in vacuum filtration. When the reagents were used in conjunction with a pressure filter, higher degrees of moisture reductions were achieved. In the present work, the novel dewatering aids were tested using different types of pilot-scale vacuum filters. The results were consistent with those obtained in laboratory experiments.

Jan 1, 2003

By L. P. James, W. W. Atkinson

Utah has produced about one billion troy oz. (31.7M tonnes) of silver, more than any U.S. state except Idaho. Several very high grade ore systems, now closed, occur within large polymetallic limestone-hosted districts related to plutonic complexes. These Utah mines fed several major lead smelters for nearly a century. Interaction of magmatic chloride-rich fluids with carbonate rocks localized significant bonanzas within these districts. A low sulfidation state was produced in the fluids by their passage through limestones. The Bingham porphyry mine has also yielded more byproduct silver than other porphyry copper-gold systems. Away from exposed intrusive rocks, some large silver-only systems occur in Mesozoic sandstone and in caldera-related veins in volcano sedimentary rocks. Thick permeable latest-Proterozoic basement meta quartzite sequences present beneath western Utah may have been important, as perhaps they were in the Coeur d’Alene district of Idaho, in providing chloride and silver-rich ore fluids. However, it is clear that specific Tertiary magmatic events played an essential role in the evolution of the Utah silver-rich metallogenic province. The largest silver districts in the state are genetically related to porphyritic plutonic rocks.

Jan 1, 2000

By Poltak Sinaga

PT Kaltim Prima Coal?s 13.1 km overland conveyor (OLC) was commissioned in 1991. It is of conventional 3 roller 350 trough belt type. Cost and performance optimization during initial design ended up with 5.4 mps belt speed, 1000 mm belt width to convey 1350tph, and 7 mtpa of coal. Despite high initial figure, the belt speed was lifted to 6.5 mps in 1996 to accommodate mine throughput increase. In 2002, new low loss ST2100 1100mm wide belt replaced the old ST2250 due for change-out. An upgrade project was initiated at the end of 2003 to further increase the belt speed to 8.5 mps, hence to increase the OLC capacity to 30 mtpa (million ton per annum). Performance data, experience of site personnel, site observation and tests, benchmarking, and information from equipment manufacturers were major inputs to the design review. The project fast track was another challenge in addition to executing modifications on a production lifeline. The project was completed within fifteen months and the OLC was successfully commissioned at 8.5 mps belt speed in February 2005. The OLC has been to date conveying 4 200 tph satisfactorily.

Jan 1, 2008

By L. Ozdemir, M. Cigla

This paper presents and discusses some of the computer models developed and currently used at the Earth Mechanics Institute (EMI) of the Colorado School of Mines (CSM). These include the performance models for full and partial face machines. Examples of input and output of these models will be illustrated for typical mining operations by using machines such as Tunnel Boring Machines (TBM), Continuous Miners (CM), Marietta borer miners and longwall drum shearers. The general approach to modeling and the available models are discussed and some examples of these models are presented. The comparison between the estimated and achieved performance, as well as the degree of improvement in the performance due to balancing and modification in cutterhead design are also discussed.

Jan 1, 2000

By Gary Almeraris, Vincent Jr Tirolo

Traditionally, “Means and Methods” were the sole responsibility of Contractors. However, because of a number of litigious projects in the 1970s, Owners and their Engineers began including Suggested Methods of Construction (SMC) in Contract Drawings. By the late 1990s these SMCs were becoming baseline “Means and Methods” with Contractor recommended changes often considered as Value Engineering proposals. By 2004, the word “Suggested” was sometimes changed to “Prescriptive.” Owners are also purchasing TBMs and other mining equipment for Contractors prior to bid. Is limiting the contracting community’s innovation in developing their own “Means and Methods” and selecting their own equipment in the best interests of the Owner? Does it reduce the Owner’s, Engineer’s or the Contractor’s risk? Are claims reduced and finally what is the impact on the bid? A questionnaire was sent to more than fifty senior engineering field and management personnel representing more than 30 heavy construction companies to ask their opinion on these questions.

Jan 1, 2005

By Thomas J. Crocker, Douglas B. Uthus

Tunnel Boring Machines (TBM) have gained worldwide acceptance in the construction field and are being employed in ever increasing numbers to drive underground transit lines, drainage systems, etc. However, TBM utilization in the mining industry, and more specifically coal mining, has been very limited. This paper reviews past and present applications of TBMs to coal mining and examines the needs of the industry in an attempt to offer some insight as to what a TBM system must provide if the excavation potential demonstrated in civil works projects is to be realized in coal operations. EUROPEAN EXPERIENCE Germany The Germans recognized long ago the potential of mechanized drivage for coal mine entry development. Early in the 1960&apos;s experimental runs were made with a full-face Wohlmyer roadheader at the Westerholt Mine and trials were conducted on a roller bit armed full-face Bade roadheader. But because of problems with penetrating the various carboniferous strata occurring in changing sequence and hardness, these first attempts were soon terminated. After viewing later successes in the construction industry with improved TBMs, new attempts were initiated by the German mining industry in 1971 to mechanize drivage of their development entries. Four TBMs of two different types were placed in operation.

Jan 1, 1976

By Marcus A. Wiley, Gregory Abramov

Borehole mining (BHM) is a remotely operated method of extracting rock material through boreholes by high-pressure water jets. Figure 1 illustrates a BHM tool and fluids circulation. The tool consists of at least two pipes, one for pumping down high-pressure water, the second for delivering slurry to the surface. This article reviews the BHM process. It discusses current and new applications for borehole mining and help the readers determine if BHM is applicable in their situations. Previous articles in ME about BHM explained either a particular project (ME, April 2001, pp. 33-36) or a newest patent in this area (ME, March 1991, pp. 313-318). However, neither one provided an overview on the modern BHM technology.

Jan 1, 2004

By Daniel M. Flanagan

"Editor’s note: Each year, Mining Engineering features an industrial minerals review. Several people put in a fair amount of time in developing the material for this issue, all the while doing their own jobs. Thank you to the industrial minerals annual review editor, to the Industrial Minerals & Aggregates Division technical committee chair and vice chairs, and to the authors of the individual commodity profiles. Jim Norman, member SME, of Tetra Tech, is the industrial minerals annual review editor.Joe Garska, member SME, of Imerys, is chair of the Industrial Minerals &Aggregates Division’s Technical Committee.The technical committee vice chairs include:• Hyunjung Kim, member SME, of Chonbuk National University, agricultural materials.• Xihui Lin, member SME, of Kemira, ceramics and refractory materials.• Nikhil Gupta, member SME, of Virginia Tech, chemical raw materials.• Adam Rodriquez, member SME, of Penn State, construction aggregates.• LeDeana Roberts, member SME, of Imerys, fillers and pigments.• Harsha Kolla, member SME, of ChemEOR, sorbents, filters and process aids.• Edgar Blanco, member SME, of FLSmidth, specialty minerals.Their help makes possible this July industrial minerals issue. On behalf of ME readers, the editors thank them.During the past 25 years, U.S. ball clay production (the quantity sold or used by domestic producers) increased from 788 kt (869,000 st) in 1990 to an alltime high of 1.31 Mt (1.44 million st) in 2003 (Fig. 1). Housing construction within the United States, a leading market for ball clay-based ceramics and sanitaryware, began to decline in 2005, which resulted in a considerable decrease in sales of ball clay that continued through the 2008-2009 economic recession. After bottoming out at 831 kt (916,000 st) in 2009, ball clay production steadily increased through 2015 (Fig. 1). Estimated sales in 2015 were 36 percent higher than those in 1990 and 18 percent lower than those in 2003.Four companies (H.C. Spinks Clay Co., Imerys S.A., Old Hickory Clay Co., and Unimin Corp.), mined ball clay in five states during 2015. An estimated 1.7 Mt (1.18 million st) of ball clay valued at an estimated $47.5 million was sold or used by U.S. producers, a 4-percent increase from 1.03 Mt (1.14 million st) valued at $45.2 million in 2014. Approximately 65 percent of total ball clay production was air-float, 25 percent was crude or shredded and 10 percent was water-slurried"

Jul 1, 2016

By J. D. Miller, C. L. Lin

In the processing industries, it is well known that particle shape is an important factor which determines the behavior of particulate systems. For example, system properties of technological significance including rheology, suspension stability, agglomeration, packing, permeability…etc, are affected by particle shape. In this regard, characterization and analysis of particle shape is essential for more detailed understanding and improved development of particulate processes. In general, it is clear that the behavior of these systems depends on the statistical characteristics of particle shape. Remarkably few techniques exist to predict the mechanical and hydrodynamic behavior of an irregularly shaped particle or a population of irregularly shaped particles for that matter. The lack of models and correlations can be attributed to the wide variety and complexity of particle shapes, the difficulty of defining shape descriptors suitable for modeling, the limitations of measuring shape, and the lack of classifying techniques to characterize particle shape. In this paper, we present information on how 3D particle shape can be measured, characterized, and analyzed using cone-beam X-ray microtomography (XMT).

Jan 1, 2005

By Jose A. Gomez, Javad Sattarvand

Failures of tailings dams have been happening lately. Due to the lack of laws on particular design criteria and stability requirements related monitoring during construction and maintenance, they are thought to be more fragile than hydraulic dams. Monitoring the dam is therefore necessary to understand its current condition and guarantee its safety. The physical condition of the dam could be evaluated with the early identification of seepage. Additionally, due to their adaptability and capacity for high-resolution data collecting, UAVs are an excellent choice for efficiently covering the tailings dam site. UAVs may capture high-quality photos when equipped with a high-resolution RGB camera, thermal sensors, or multispectral sensors. When these sensors are paired with image processing and machine learning algorithms, the result is a reliable estimate of the dam condition.

Jun 25, 2023

By E. D. Attanasi

Geologic resource assessments describe the location, general characteristics, and estimated volumes of resources, whether in-situ or technically recoverable. Such compilations are only an initial step in economic resource evaluation. Forecasts that assume that resources that exist in nature can be commercially produced as needed ignore economic constraints. This paper identifies, by example, the salient features of a geologic assessment that will assure its usefulness for economic analysis. These features are demonstrated with examples of coal resource assessments and coal bed gas assessments.

Jan 1, 2001

By R. Karl Zipf

Highwall mining is an important surface coal mining method, and it may account for approximately 4% of total U.S. coal production. Highwall stability is the major ground control related safety concern. Ground control plans for highwall mining should specify hole width, web pillar width, barrier pillar width and number of holes between barriers. This paper offers simple design charts for these parameters aimed at providing “ball park” checks. Web pillars containing pre-existing auger holes are analyzed and a design chart for estimating their minimum width is also presented. Finally, close proximity multiple seam highwall mining, which may have caused several serious highwall failures, is analyzed. Web and barrier pillar recommendations for this special situation are presented.

Jan 1, 2005

By B. J. Sauer

Variable frequency drives (VFD’s), or adjustable frequency controls (AFC’s) as they are more precisely identified, have been available to the mining industry for over 20 years. However, in recent years as the push to cut production costs has become ever so crucial, AFC usage has become more widespread. This paper seeks to provide professionals in mineral processing plant design and operation with an introduction to AFC’s, insight as to why AFC control for AC induction motors can be advantageous, and specification and design considerations.

Jan 1, 2002

By Steve Kral

Not too many years ago, mining was in one of its cyclic down-sides. This forced mining companies into some innovative thinking to bring down the costs of production. And they have. Mining equipment and processing plants have become more efficient, mostly due to technological advances. The mining industry is now in a boom period, one that some analysts believe can sustain itself. But even with higher commodity prices, sky-rocketing energy costs and the costs associated with environmental and reclamation regulations have not allowed all mines to reach their full profitability potential.

Jan 1, 2006

By J. Barrett

State-of-the-art wireless communication and location-tracking technologies will dramatically change the face of mine worker safety. The MineTracer System developed by a Liberty Lake Washington company is a broad capability wireless sensor network based on a new breed of technologies known as wireless mesh systems. In this paper, R&D Manager Jim Barrett summarizes the balance of engineering tradeoffs that result in a system that (1) performs well, (2) is survivable against many types of mine accidents, (3) operates for many hours post-accident on battery power, (4) meets stringent MSHA requirements for intrinsic safety, and (5) is economically affordable for the mines.

Jan 1, 2009