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U.S. Borax’s mine in California’s Mojave Desert is the source of nearly half the world’s supply of refined borates. These minerals are used in hundreds of products, including essential plant nutrients that increase crop yield and quality, and safe building products that protect homes from insects and the elements. Borax’s workforce is also safe. In fact, it is among the safest in the nation. In 2003, the company was recognized by the U.S. Mine, Safety and Health Administration (MSHA) for achieving the best safety record among large U.S. mining operations. It was also recognized by its parent company, Rio Tinto, for achieving the best record among its nearly 80 worldwide mining operations. Borax’s safety performance is five times better than the national average. And its workforce recently achieved more than two million hours without a lost-time injury.

Jan 1, 2004

By Jan L. Reichelderfer, Thomas L. Richardson

Completion of the H-3 Highway Tunnel Project was a critical element in opening this award winning project. The exploratory tunnel was completed as a maintenance tunnel and included difficult shafts extending into the main tunnel cross passages. The project also involved a major addition to the traffic operations center including a deep excavation in close proximity to the tunnel portal structures. The projects also included various completions and improvements to the main tunnels, such as paving, drainage, maintenance, and a variety of critical life-safety issues, such as radio systems, telephones, etc. The highway opened in December 1997.

Jan 1, 2001

By Tuncel M. Yegulalp, Anuta Belova

This paper expands on the ZECA (Zero Emission Coal Alliance) technology, which is aimed at making coal a sustainable source of clean energy in the near future. The technology proposed immediate capture of carbon dioxide and other pollutants upon generation, thus alleviating their negative effects in the Earth’s atmosphere. ZECA proposes using chemical energy of coal to produce hydrogen; the latter is then used to produce electricity via fuel cells or Hyrogen-Oxygen turbines. In this study, a chemical engineering package, AspenPlus 12.1, is used to simulate the reactor (reformer) in which hydrogen is produced from methane water and lime as part of the zero emission power plant. Thermodynamic conditions, pressure and temperature, are optimized with respect to molar hydrogen production. Under the proposed conditions, molar conversion efficiency, carbon to hydrogen, of 95% is achieved. Further studies are required to model the complete power plant and to optimize it for efficiency.

Jan 1, 2005

By D. H. Garcia

The mining industry responded to public concerns about use of cyanide by developing a voluntary certification to allow companies to demonstrate their commitment. The International Cyanide Code (Code) establishes standards for the manufacture, transportation and use of cyanide. Key concepts in closure planning to comply with the Code are to decommission all facilities related to cyanide operations and to provide a financial assurance mechanism for those activities. Code requirements may differ from state-specific regulations, but requirements are based on closure goals for protection of the human health and the environment. Only issues related to cyanide operations are required to be included in decommissioning demonstrations. For example, the disposal method of cyanide solution holding tanks and the cost must be included in the closure plan, but information regarding closure of roads is not required. Closure costs must be based on a third-party contractor as opposed to internal budgets. Compliance with the closure requirements of the Code allows companies to show their stockholders, lending institutions, and the public that their operations are environmentally responsible.

Jan 1, 2010

By Y. Wang

China is a big mining country with a long mining tradition and history. At present, there are nearly 200,000 different mines and 21 million workers. The total production value of mining makes up 6% of GNP. With the development of economy, the mining industry has played a more important role in our economic market, supplying more than 95% non-reusable energy, 85% of industrial and agricultural raw materials, over 75% of fertilizers and 30% industrial and agricultural water.

Jan 1, 2001

By Robert A. Jankowski, J. Harrison Daniel, Fred N. Kissell

Introduction Longwall coal mining in the US has steadily increased since its introduction in 1960. There are now 108 systems operating. (Sprouls, 1986). Advantages of longwall mining include higher productivity, improved safety, and greater coal recovery. Respirable dust, however, is one of the more serious obstacles to realizing the full potential of longwall mining. Early in 1980, the US Bureau of Mines (USBM) initiated extensive in-house and contract research to identify and evaluate effective methods of controlling respirable dust exposure of longwall face personnel (Niewiadomski, Jankowski, and Kissell, 1981). It was found that several control procedures must be combined to assure compliance, using control techniques appropriate to the dust source. These techniques can typically be grouped into the following categories: reduction of dust generation; dilution of dust; capture or knockdown of dust; and dust avoidance. Control techniques can be divided into basic and effective dust control techniques; additional necessary controls; and optional supplementary controls. This information should allow longwall mine operators to select control methods applicable to their particular operations and to develop a dust control plan that meets Federal dust standards. Basic and effective dust control techniques There are three basic dust control techniques (Taylor and Jankowski, 1982) that should be implemented on all longwall mining operations. • A passive barrier or external water spray system design that confines shearer generated dust near the face and away from the operators. • Large quantities of water through the sprays, particularly the drum sprays, to aid in dust knockdown and prevent dust becoming airborne. • A cutting sequence that allows the shearer operators to work primarily on the intake-air side of the lead cutting drum. Shearer clearer There are some poorly designed shearer-mounted spray systems with nozzles directed upwind at the cutting and loading zone of the intake-side drum. These actually carry dust away from the face and upstream of the drum. Where, it mixes with the clean intake air (Fig. la,) and is carried out into the walkway over the shearer operators. The Bureau developed a novel shearer spray system, called the shearer clearer. It takes advantage of the air-moving capabili-

Jan 10, 1986

By W. J. D. Stone

In 1960, Magnetics International Ltd. undertook the development of the Jones High Intensity Wet Magnetic Separator in the Americas. Magnetics International had a number of possible applications in its own projects plus the intention of developing the equipment for sale to others. It was soon recognized that no matter how innovative a piece of mineral separation equipment may be, it takes many years and much finance before it is finally accepted for large scale use. For this reason, many good ideas die in their infancy. One of the chief reasons for such a time lag between conception and large scale implementation is the usual lack of finance to construct and put into operation a large demonstration unit. Even with a large unit for demonstration, the first major user usually requires a guarantee that is not normal in accepted separation equipment. Such problems are also normally accompanied by major design changes from the first conception.

Jan 1, 1971

By J. Humphries

With today?s turbulent markets and unprecedented global opportunities, the need to optimize net present value and internal rates of return from capital investments has never been greater. To help address the need, this paper presents an overview of the key processes and strategies for achieving maximum return from capital projects. Best practices discussed address stage gate management for project evaluation, selection, and oversight, project execution efficiency, value improving practices, operational readiness, and operational excellence. The paper also includes a model of key metrics and benchmarking with tips for application. [ ]

Jan 1, 2011

By Daniel J. Dobbels, Eric R. Drooff, James R. Wheeler

Construction of Boston’s C11A1 Section of the Central Artery (I-93)/Tunnel(I-90) Project beneath the existing MBTA Red Line Subway at South Station required excavation to depths in excess of 33.5 m (110 ft) through permeable sand and gravel subject to almost 27.4 m (90 ft) of hydrostatic groundwater pressure. As tacked drift tunnel underpinning system was designed to provide positive support to the active station prior to mainline tunnel construction. As part of this system, a permeation grouting program was developed to facilitate tunnel excavation. This paper describes the design and implementation of the grouting program, in sit testing, and the overall performance of the grouted soil mass.

Jan 1, 1999

By S. Dessureault, Z. Gavelan

As globalization continues, sustainability and social responsibility has become essential in foreign mining investment. However this global trend and the increasing acceptability toward the globalization process, viability and sustainability are not always achieved. Viability and sustainability of mineral projects is dependant on the social and political environment of the region where the mining venture is located and is based on the interaction between the mining entrepreneurs, national-local government representatives, communities, grass-roots groups and independent civil organizations. These are the organizations, which play the acting roles on the viability of mining projects and are the main source of socio-political risks for the project. Throughout the decision-making process to invest in a mineral project, socio-political risks are quantified using a set of measurable variables. Nevertheless, these risk measures should be dependent on specific industries. Two mineral projects, even in the same mining district, may have significantly different political risk profiles based on their own socio-political variables. This paper describes a methodology that takes into account local social and political variables in defining a project-specific’s political risk profile. This contrasts with more typical political risk measures that focus on the country’s overall risk profile. Mining operations must operate on a local scale necessitating the development measure that considers more local variables.

Jan 1, 2004

By Sam Ash

The Murray Mine was one of the first mechanized cut-and-fill underground gold operations in northern Nevada. At the end of 2002, mine production began to decline. So the mine entered a phase of remnant mining and began preparations to close down. The remaining mining took place along the ore waste boundary in previously condemned areas and in challenging ground conditions. To remain economically viable, new techniques were implemented in operations, geology, engineering and rock mechanics. These improvements pushed the edge of known and accepted mining practices and have allowed the Murray Mine to remain in operation.

Jan 1, 2006

By J. D. Potts

Installation of a horizontal air blocking shelf around the inside perimeter of the surface mining drill deck shroud is proposed to improve dust capture. Without the use of this shelf, a strong coanda effect airflow pattern results in dust leakage to the environment, especially at the shroud-to-ground interface. Bailing air exits the drill hole and travels along the drill steel to the underside of the table, where it fans out across the bottom of the drill table and continues down the sides of the shroud. This dust-laden bailing air then strikes the ground and fans out under gaps between the shroud and the ground. The proposed shelf prevents dust-laden air from striking the ground by redirecting it toward the center of the enclosure, where it can be captured. Laboratory tests demonstrated that the shelf reduced dust levels outside of the shroud by 81% under operating conditions consisting of a 1.9:1 collector to bailing airflow ratio, and a 5.1-cm (2-in) gap between the shroud and ground. The shelf was 15.2-cm (6-in) wide and located at a height equal to 2/3 the distance measured from the bottom of the shroud to the bottom of the drill table. The air blocking shelf was also capable of overcoming the adverse impact of vertical leakage along the shroud seams as long as this leakage was confined to an area below the horizontal plane defined by the shelf location.

Jan 1, 2009

By B. Samoski

In late 1994, EPA and OSM acknowledged that efforts by any one agency or by the many different agencies to remedy the water quality impacts of decades of contamination from abandoned coal mine lands in Appalachia would not be successful if their disjointed efforts were not unified and if the local watershed organizations were not included. The result of the collaboration between EPA and OSM was the creation of a statement of mutual intent which was a pledge by government agencies, watershed organizations, and the industry to restore watersheds degraded by acid mine drainage from abandoned coal. The presenter will describe the evolution of this pledge from a paper promise to on-the-ground remediation projects.

Jan 1, 2002

By J. Chai

In order to find the behavior of dewatered unconsolidated strata during the process of injecting water through a borehole, a new type of fiber Bragg grating (FBG) sensing system was successfully used for the real-time strain monitoring of unconsolidated strata during a water injection process for a dewatered unconsolidated strata of a coal mine. The unconsolidated strata water injection test was implemented through a borehole at a depth of +115.83 to +135.15m. The employed FBG strain monitoring system and ground water level observation system were installed at the depth in the unconsolidated strata where the water injection was conducted through two different boreholes. The water injection pressures in the test were 0.1, 0.2, 0.3MPa respectively, and the total water injection volume was 4226.84m3. The relationships between the water injection pressures, water injection volume and the strain change of the unconsolidated strata, the stress and strain conditions of the unconsolidated strata before and after water injection, were analyzed. This paper presents the results of these tests, and shows that the dewatering compression of the unconsolidated strata is reduced with increasing water injection pressures and water injection volumes. Comparing the stress-strain conditions before and after water injection, it is found that the stress of the water injection strata is in tension, which confirms the theory that the settlement of the thick unconsolidated strata is directly caused by the reduction of ground water levels. The high sensitivity and stability of the FBG monitoring system used was able to realize the real-time strain monitoring of the water injection process within a deep unconsolidated strata. This FBG monitoring system and the test results presented are very important for understanding further treatment of settlement in unconsolidated strata.

Jan 1, 2012

By M. K. Mohanty

One of the main objectives of this study was to evaluate a fine-coal cleaning circuit using an enhanced gravity separator specifically for a high sulfur coal application. The evaluation not only included testing of individual unit operations used for fine-coal classification, cleaning and dewatering, but also included testing of the complete circuit simultaneously. At a scale of nearly 2 t/h, two alternative circuits were evaluated to clean a minus 0.6-mm coal stream utilizing a 150-mm-diameter classifying cyclone, a linear screen having a projected surface area of 0.5 m2, an enhanced gravity separator having a bowl diameter of 250 mm and a screen-bowl centrifuge having a bowl diameter of 500 mm. The cleaning and dewatering components of both circuits were the same; however, one circuit used a classifying cyclone whereas the other used a linear screen as the classification device. An industrial size coal spiral was used to clean the 2- x 0.6-mm coal size fraction for each circuit to estimate the performance of a complete fine-coal circuit cleaning a minus 2-mm particle size coal stream. The ?linear screen + enhanced gravity separator + screen-bowl circuit? provided superior sulfur and ash-cleaning performance to the alternative circuit that used a classifying cyclone in place of the linear screen. Based on these test data, it was estimated that the use of the recommended circuit to treat 50 t/h of minus 2-mm size coal having feed ash and sulfur contents of 33.9% and 3.28%, respectively, may produce nearly 28.3 t/h of clean coal with product ash and sulfur contents of 9.15% and 1.61%, respectively.

Jan 1, 2008

By R. H. Zeng

Many subsidence researchers in the U. S. have developed new empirical function methods to predict subsidence, or attempted to validate some empirical functions developed by foreign researchers for use in the U. S. An attempt is made in this paper to develop a new empirical function to predict a surface subsidence basin due to longwall mining. In the U. S., the emphasis of empirical methods for the subsidence prediction over longwall panels has been in large part on determining the profile functions for the major cross-sections of a subsidence basin. In this approach, the surface monuments are usually laid out along the major cross-sections and thus, the subsidence profiles developed are restricted for subsidence prediction along the major cross-sections. However in practice many monuments or surface structures for which subsidence prediction for damage evaluation is required, are not laid out along the major cross-section of the basin. In such cases, it is difficult to get either the empirical profile function for the cross-sections where these structures are located or to predict their subsidence based on the profile function developed for the major cross-sections. Therefore, there exists a strong need to develop a subsidence basin function with a reasonable degree of accuracy, which can be determined or confirmed by the data of scattered monuments on a surface basin. The same subsidence basin function can also be used for prediction of subsidence for any arbitrary points over a longwall panel. In 1982, He (1) proposed the clastic theory, for which he developed the basic differential equations describing the movement and deformation of overburden due to underground mining, and performed the selection of best solution for the equations. He found that the Weibull dietribution is the optimal solution. The Weibull distribution has three parameters that vary to fit the subsidence profile so well that the profile function derived from it provides a high degree of accuracy in subeidence prediction. However the results

Jan 1, 1986

Fully mechanized longwall mining with large mining heights (LMHs) in shallow-depth thick coal seams has been widely applied in Shenfu coalfield, China. Dynamic loading and rib spalling is serious when the LMH working face experiences periodic weighting in shallow coal seams. The advanced breaking position (fracturing ahead of the face) in the roof affects the strength of the mine pressure (weighting) when the roof is broken. Based on the theory of the “elastic foundation beam,” this paper presents a mechanical model for the advanced breaking of the roof, including a predictive formula. In an attempt to verify the formula, a field program consisting of multiple-point borehole extensometers installed in the roof in advance of the longwall face was performed in the No. 22201 working face of Zhangjiamao coal mine in the Shenfu mining area, China. The field measurement results show that the roof movement of the LMH working face is detected prior to roof pressure increase, and that the roof breaks approximately 5–8 m ahead of the face. This compares with a calculated value of 6.9 m, indicating that the formula developed in this research is reliable and should have application in predicting roof pressure associated with LMH working faces in shallow coal seams.

Jul 28, 2020

By Frank A. Jerabek

Problems of mine backfilling and fill material deposited underground, the characteristics and relationship between the deposited fill material and overlying ground, and the practical applications and limitations of hydraulic backfilling as ground support are discussed. A great variety of materials ranging from coal washery refuse to concentrator tailings is used as hydraulic fill. Some materials will solidify and cement; others will resemble quicksand, Hydraulic fill as ground support is more efficient in inclined mine openings than in horizontal mine openings, where it cannot be placed tightly to the back. This and other deficiencies of hydraulic backfilling led to the development of pneumatic stowing. Research work in hydraulic backfilling at the Pennsylvania State University is also discussed. This research work includes the investigation of segregation in the discharged fill slurry, the quantity of solids escaping in the drain liquid, the relationship of escaping solids to slurry concentration and discharge rate, and the compressibility of fine fill material.

Jan 1, 1965

By B. Das

Hematite floatability from two low grade banded iron ores of India, namely banded hematite quartzite (BHQ) and banded hematite jasper (BHJ) using fatty acids and amine as the collectors is investigated under identical physico-chemical conditions. The results indicated that hematite present in BHQ ore is easy to float using both the collectors, compared to BHJ ore. The difference of flotability between the two banded iron ores is that quartz grains are coarser and well liberated below 100 micron size in case of BHQ compared to BHJ ore. In case of BHJ ore, fine hematite and quartz grains are intimately inter-grown and are dispersed in thick jasper bands leading to liberation problems. Besides that, dusty jasper particles coat over hematite surface in case of BHJ ore during the process of grinding, which hinders specific adsorption of collector on hematite or quartz surfaces. This is substantiated by scanning electron microscopy (SEM). The flotation studies have indicated that it is possible to achieve ~64% Fe with ~67% recovery from a BHQ ore using both anionic and cationic collectors from a feed containing around 38% Fe. In contrast, the hematite recovery in BHJ ore was poor. Differences in the ore characteristics that affect the flotability of hematite present in both the ores are compared. Keywords: Banded hematite quartzite, banded hematite jasper, flotation, oleic acid, dodecylamine, QEMSCAN, Scanning electron microscope

Feb 27, 2013

By D. Bernabe

The mine scheduling process defines a mining sequence across the life of the mine and stipulates the amount of ore, waste, and specific blocks to be mined each year so that the highest economic return can be obtained under a number of constraints. There are a number of mine scheduling software packages available. Each claims to be the best scheduler by maximizing Net Present Value (NPV) or by minimizing overall mining costs. These mine scheduling programs follow different procedures and scheduling philosophies based on either mathematical or heuristic principles. There was no study in which the mine production scheduling procedures applied by these packages were discussed and compared. This paper evaluates four open pit mine scheduling programs recently developed and compares them in order to determine if significant differences exist among them. The same input data, which consist of a 3-D block model, an economic set of parameters, and the initial surface topography for a operating copper mine in Southern Peru, was used to test each technique. The following programs were investigated with respect to their ability to optimize the NPV for the case study. 1) M821V1 Scheduler by Mintec; 2) NPV Scheduler by Earthworks; 3) Milawa Scheduler by Whittle Programming; and, 4) Fundamental Tree Scheduling Method (FTSM) developed at the Colorado School of Mines. The results from this case study demonstrate that the scheduling software packages, Mintec, Earthworks, and Whittle obtained similar NPV’s, while FTSM scheduler gave a six percent higher NPV than the other schedulers.

Jan 1, 2002