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By Wayne Hilgedick

Peabody Coal Company is the nation's largest producer of coal and is headquartered in St. Louis, Missouri. In 1978 Peabody divisionalized its operations to establish more responsive and effective mine management. Peabody Coal Company's Arizona Division operates two large surface mines, the Black Mesa and Kayenta Mines. Both are located in northeastern Arizona, approximately 30 miles from Kayenta, Arizona, on the Navajo and Hopi Indian Reservations. The Black Mesa Mine produces 4 to 5 million tons of coal per year and the Kayenta Mine produces 7 to 8 million tons per year. Coal from the Black Mesa Mine is transported 274 miles by coal slurry pipeline to the Mohave Generating Plant located on the Nevada/Arizona border at Bullhead City, Arizona. This plant is jointly owned by Southern California Edison, the Los Angeles Department of Water and Power, Nevada Power Company and Salt River Project Agriculture Improvement and Power District.

Jan 1, 1983

In order to overcome some of the deficiencies associated with conventional fine coal cleaning methods, a novel process known as microbubble column flotation (MICROCEL?) was developed at Virginia Tech. This article provides an overview of recent commercialization efforts and in-plant testing of this technology. The results of the in-plant test work indicate that the MICROCEL technology offers several advantages for the upgrading of difficult to clean coals. The test data have also been used to develop guidelines for the design of coal flotation columns and to validate existing scale-up procedures.

Jan 1, 1991

By Mike Wongkaew, Brandon Kluzniak, Per Vilhelmsson

Rail access to Ontario International Airport (ONT) has long been a goal of San Bernardino County Transportation Authority (SBCTA) to increase public transit options to ONT and provide incoming ONT passengers improved access to San Bernardino County and the greater Southern California region. This paper describes the planning for the Design-Build-Operate-Maintain (DBOM) delivery of an emerging technology tunnel connection between the Rancho Cucamonga Metrolink station and ONT. The paper discusses key technical considerations, challenges, and opportunities; conceptual configuration development; and construction planning and establishment of the footprint for the underground connection.

Dec 1, 2022

By K. Boakye, T. Newman, P. Bláha, M. B. Toelle

"This paper presents a quarry optimization plan using a block model and an in-house development quarry scheduling and optimization software (QSO Expert) to help improve quarry operations at Crystal River. The Crystal River Quarry is an underwater quarrying operation that barges limestone via the Gulf of Mexico, as the main source of raw material to a cement plant in Theodore, Alabama. To improve the quarry operation, an evaluation was completed to optimize the quarry planning and extraction procedures of the quarry. In order to achieve this, additional exploration drilling campaign was implemented, a new block model was re-calculated and the latest version of QSO Expert software was used. The primary economic impact is a higher recovery of limestone reserves; sustainability of resources, corresponding longer quarry life. Secondarily as the limestone is mined underwater and stockpiled above water, drainage reduces moisture content achieving direct cost reduction on limestone shipping. In addition, a considerable reduction in operational cost was achieved due to a significant decrease in consumption of electrical energy, reduced dragline maintenance costs and reduced dragline movements within the operation. INTRODUCTION Holcim is a Swiss-based global building materials and aggregates company. Founded in 1912, the company expanded into France and then throughout Europe and Middle East during the 1920s. In 1922, Holderbank, as the company was then known, expanded beyond the Swiss borders into France. By the end of the decade Holderbank held stakes in Belgium, Germany, the Netherlands, and Egypt (Holcim History 1912-2012) Positions in Lebanon and South Africa soon followed.. Holder bank later expanded in North America in the 1950’s. In the late 1970s and early 1980s, Holderbank continued its expansion in Latin America, Asia and Spain for the first time. The company expanded into Eastern Europe and experienced a boom in Spanish construction preceding the 1992 Summer Olympics. By 1986, Holderbank was the world's largest cement manufacturer. In the 1990s, the company consolidated its European holdings as the American market drove growth. Expansion into Eastern Europe and Russia continued (Holcim History 1912-2012). In 2001, the company changed its name from ""Holderbank Financière Glaris"" to Holcim (short for Holderbank ciment) (Holcim History 1912-2012). Holcim expanded by purchasing Aggregate Industries entering into the United Kingdom for the first time. That year, the company also expanded into India by acquiring a stakes in The Associated Cement Companies (ACC) and Ambuja Cement Eastern. In 2008, Holcim became the largest shareholder of China's Huaxin Cement with a 40% stake. In 2009, they acquired Cemex Australia. In 2014, Holcim and Lafarge announced they had agreed to terms on a ""merger of equals"" valued at nearly $50 billion in 2015. The new company LafargeHolcim based in Switzerland has a manufacturing capacity of 427 metric million tons a year."

Jan 1, 2017

By W. J. González

With the increasing demand for minerals and the decline in the quality of ore reserves, technologies to maximize recovery are critical to a mine?s economic success. Many mining waters exhibit the potential to form hardness-based inorganic scales, which inhibit effective mineral recovery. Often, a continuously-fed chemical deposit control program is implemented by the mine site to inhibit these scales. The use of retractable scale coupons is the current industry standard for monitoring these programs; however, a key drawback to their use is the limited, and sometimes untimely amount of information they provide. A proprietary fouling analyzer has been developed that can be used to continuously monitor the formation of inorganic scales in mining process streams. Consequently, it can be used to continually, and more effectively, communicate the efficacy of an antiscalant program, thereby providing the ability to compare different scale control programs and to optimize their feedrates. Case studies presented validate the applicability of this technology to help optimize mineral recovery.

Feb 23, 2014

By Shani Engelbrecht, Belinda McFadzean, Avuyile Wali, Natalie Shackleton, Vratislav Malysiak

Frothers play a crucial role in sulphide and PGM ore flotation recovery, and AECI Mining Chemicals studies on PGM ores have shown significant flotation kinetic increases with the optimal frother-collector combinations. Using Senfroth 200 as the industry baseline, remarkable kinetic increases were observed with AECI Mining Chemicals developed frothers in the first concentrate. Even in the worst-case scenarios, 4E PGM recovery increased by 5% at a slightly higher concentrate grade. It is important not to limit frother dosage to a fixed value. Instead, enough frother should be added to maintain a stable bench float, measuring the dosages by frother volume before and after tests. Frothers can be specialized blends and their importance should not be underestimated. The results produced by formulating and innovating frothers to address specific industry challenges have been encouraging. Testing a frother on a plant scale does not have to be as daunting as with collectors, enabling the identification of the best frother-collector combinations at an industrial scale. AECI Mining Chemicals bench scale testwork has motivated plant-scale trials that have successfully transitioned to commercialization. This paper compares the results from metallurgical and froth stability tests and shows that occasionally frothers that have a less stable froth can have improved valuable mineral recoveries, while still exhibiting better drainage for reduced entrainment and mass pull. It was shown that caution should be used when relying only on simplified froth stability tests in the evaluation of new frothers.

Feb 1, 2025

By J. O. Marsden, J. H. Gourdie, J. R. Arnold, J. G. Mansanti

During the testing and design of the Gold Fields' Chimney Creek mine, it was found that a much higher carbon loading was possible with CIC (carbon-in-solution columns) than with CIP (carbon-in-pulp). In an effort to keep the carbon handling minimized, an emphasis was put on forcing gold to the CIC circuit rather than the CIP. After considerable study, it was found that a circuit with two thickeners and an interstage leach would force 90% of the gold to CIC. Computer modelling indicates that the benefits of the hybrid circuit include higher recovery, less carbon handling, fewer leach tanks, and lower reagent costs.

Jan 1, 1990

By Allen Latham

It started' in 1936 when some Dutch adventurers wanted to scale the highest mountain in the South Pacific. Quite by accident, they discovered the Ertsberg, a contact deposit of magnetite laced with chalcopyrite, in a high mountain valley where it had been gouged at by glaciers and finally left as a solitary pillar for its discovery by a geologist who lent purpose to the expedition, Dr. J.J. Dozy. By the-.time a report was published describing the deposit, war had hit the Netherlands. Perhaps again by accident, the report was uncovered in 1959 by the East Borneo Company. At this point, Freeport entered the scene through its vice president for exploration, Forbes Wilson. During the course of a meeting on laterite prospects, the Ertsberg was introduced and he put the wheels into motion for Freeport to join in its exploration. You might, at this point, ask yourself whether you or your company would have taken on a venture to look at a reportedly large high grade copper outcrop in New Guinea, an unexplored land known best for its inhospitable climate, terrain and head-hunters. I heard the chief executive of one large mining company comment sometime back that neither he nor his company would have gotten involved. I won't attempt to describe the trials of the initial exploration expedition that passed through dense-man grove swamps, tropical jungle and across jagged mountains a distance of some 200 miles to get to the Ertsberg in 1960. It should be chronicled by its participants - Forbes Wilson, Del Flint, and John Bowenkamp. Needless to say, the participants relish the experience but wouldn't be among those volunteering for a return engagement. As a result, the Ertsberg changed from a reported outcrop to a mineral deposit containing an estimated 13 million tons with systematic surface sampling indicating a copper grade of over four percent. Moreover, the deposit extended to an indeterminate depth with the possibility of doubling or tripling. reserves well within reason.

Jan 1, 1971

By S. K. Kawatra, J. A. Halt

"Low-grade iron ores are finely ground and processed to recover iron-bearing minerals. However, the iron-rich powder is too fine to be used directly in blast furnaces and most direct reduction furnaces, and must be agglomerated or pelletized into a usable product called “pellets.” Bentonite clay has traditionally been used as a binder to make iron ore concentrate pellets, but it is expensive and contaminates the pellets. Organic binders may be a viable alternative to bentonite clay. This manuscript reviews organic materials that have been used to make iron ore concentrate pellets. Included are discussions on the development of organic binders, common pros and cons to organic binder use, organic binder structure and its effects on agglomeration, and additives to organic binders.IntroductionIron ore agglomeration turns finely disseminated, low-grade iron ores into a usable product, called pellets. During pellet production, fine-grained, iron-rich minerals are liberated from low-grade ores, concentrated, and agglomerated into round balls that are thermally hardened or cold-bonded to form pellets. Pellets are then transported to blast furnaces or direct reduction operations where they are used to produce iron; iron is further refined and shaped into the wide variety of steel-based industrial and consumer products in use today.Over the years, pellet production has become increasingly more prevalent with the increased exploitation of low-grade iron ores and increased iron and steel consumption around the world. In 2010, world iron ore pellet production was 388 Mt. It could be argued that the current pellet production process has been enabled by the use of binders – practical experience has shown that it would be nearly impossible to agglomerate iron ore concentrates using rotary drums and discs without using a binder."

Jan 1, 2015

By S. S. Klima, H. Jiang, T. W. Beck, Y. Zheng

Researchers at NIOSH’s Pittsburgh Mining Research Division (PMRD) performed comparative testing of six different water sprays at pressures ranging from 689 kPa (100 psi) to 6,895 kPa (1,000 psi) in a 14.5-m3 (512-ft3) confined dust chamber. Testing was conducted to determine the effect of various pressures on each spray’s respirable coal dust knockdown ability. It is known that higher water pressures are typically preferred for lowering airborne dust concentrations, but it was important to determine at what pressure range the dust knockdown ability of each spray plateaus or reaches its minimum dust concentration. Results from this testing showed that several sprays saw up to 100% decrease in dust concentrations during the five-minute water spray testing period, with some occurring well below the maximum 6,895 kPa (1,000 psi) spray pressure.

Feb 1, 2023

By J. A. Organiscak

Two types of airflow splitting methods for improving longwall dust control were investigated by NIOSH's Pittsburgh Research Laboratory. These methods included a translucent mesh barrier and a staged spray barrier system to confine the shearer-generated dust to the coal extraction side of the long wall face while maintaining a cleaner split of airflow on the opposing worker walkway side of the longwall face. The translucent mesh barrier was shown to provide notable dust control effectiveness up to 60 m downstream of the shearer in both the laboratory experiments and a long wall field evaluation, provided the mesh barrier remains relatively parallel to the airflow. The staged spray barrier system showed marginal dust control effectiveness in the laboratory and subsequently was not field tested.

Jan 1, 1999

By Shankar Kumar, Arvind Kumar Mishra, Chitranjan Prasad Singh

Formulating a predictive model for blast-induced ground vibration (BIGV) has always been challenging due to the complex non-linear relationship between the BIGV and its influencing factors. Researchers have used empirical, artificial intelligence methods and numerical modelling methods to predict BIGV. In a dragline bench blasting, a massive quantity of explosives is used compared to other loading machinery, and the height of the bench depends on the size of the dragline. For effective utilization of explosives energy, decking is used to reduce the hazardous effects of blasting. In this paper, an attempt has been made for effective prediction of BIGV, and its mitigation on dragline bench blasting considering a deck length, stiffness ratio, hole spacing to burden ratio, hole depth to burden ratio, the distance of monitoring PPV from blasting site, Schmidt hammer rebound number of the bench to be blasted, and maximum charge per hole to total charge per blast. So artificial neural network (ANN) model and random forest (RF) model have been developed considering the parameters mentioned above. For the statistical performance of the predictive model, the coefficient of determination (R2) value is 0.8895, MSE is 22.84 for the ANN model, and the random forest (RF) model whose R2 is 0.8165 and MSE is 27.18. The sensitivity analysis results show that stiffness ratio, deck length, and Schmidt hammer rebound number are more influential parameters out of the selected parameters. The reduction of ground vibration with the introduction of decking led to a 3 to 15% reduction in ground vibration.

May 15, 2024

By B. A. Slaker, T. Miller

"An underground limestone mine in eastern Ohio was experiencing significant floor heave and roof falls, attributed to high horizontal stresses. Areas of the mine showing floor heave were monitored with roof-to-floor extensometers and photogrammetry surveys, to determine the rate and magnitude of heave. Extensometer data were recorded hourly at four locations across adjacent entries while photogrammetry surveys of the floor were performed at the same locations every two to five weeks. A final survey was performed using an I-Site 8200 laser scanner. Following instrumentation, floor heave up to 10.1 cm (4 in) was measured by the extensometers, photogrammetric reconstructions, and laser scanner over a 6-month period. The extensometers were biased by the location where they were placed, failing to consistently capture the location and extent of floor heave and cracking. The photogrammetry surveys were not precise enough to capture small magnitude movements. Mining in the area was halted and within several months the floor movement and incidence of roof falls was significantly lessened. INTRODUCTION Limestone formations in the United States can be subject to relatively high horizontal stresses due to the presence of tectonic loading of the strata. Horizontal stresses have a documented history of causing stability issues in underground limestone mines. Kuhnhein and Ramer (2004) discussed the influence of horizontal stress on complex ground control interactions associated with limestone pillar design and mine layouts. Esterhuizen et al. (2008) documented roof damage observations associated with high horizontal stresses such has roof guttering, beam instability, oval-shaped falls, and failure propagations. There have also been a number of documented case histories of horizontal stress causing unexpected roof and pillar failures at shallow depths (Stacey and Yathavan, 2003). To the knowledge of the authors, there has only been one well-documented case of floor failure causing stability issues in an underground limestone mine. Murphy et al. (2015) documented the role that a weak, moisture-sensitive floor had in the development of a massive roof collapse. For this paper, the study site neighbored, and was in the same general geology of, the site in Murphy et al. (2015). However, the weak, moisture-sensitive floor was not present for the current study. The current study site has experienced significant floor instabilities caused by high horizontal stresses. The instability area was monitored using two different methods to determine if the floor failure would eventually propagate into roof or pillar failure. The objective of this paper is to analyze displacement monitoring measurements from string potentiometers and remote sensing techniques in an area experiencing active movement. Based on the measurement trends and observed damage from inside of the mine, the presumed failure process will be discussed."

Jan 1, 2017

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 Haydn H. Murray

In 1967 a large kaolin deposit was discovered on the Jari River, a tributary of the Amazon, in the territory of Amapa in Brazil. The kaolin occurs in the Barreiras Series of Pliocene age and is part of the Belterra Clay. The kaolin was drilled and tested, and today a modern processing plant is producing over 150,000 tons per year of high quality paper coating clay. Some of the problems associated with the mine development, processing, personnel, and marketing of this remote kaolin deposit are discussed. The mineralogy and physical properties of the Jari kaolin deposit are also described.

Jan 1, 1981

By Duane L. Whiting

The National Environmental Policy Act of 1969 (NAPA) provides guidance for federal agencies in making informed decisions. The Act has been used to determine the potential environmental impacts from mining and other natural resource operations, primarily in the Western USA. To accomplish the purpose of the Act, a process for developing environmental documents was established. The documents (EA/EISs) evaluate environmental impacts and are produced by federal agencies through public participation and cooperating agency review. Effective interactions and up front coordination between agencies and industry is required. An abbreviated history of environmental protection in the USA leading to NEPA, the driving regulation, objectives, provisions and limitations of the Act, and select mining related NEPA projects III the Western U.S. are discussed in this paper.

Jan 1, 1998

By E. F. Divers

In response to a request from the Mine Safety and Health Administration, the Bureau of Mines has recently completed a respirable dust survey of 18 U.S. coal preparation plants. Of these, three were essentially free of dust problems. Respirable dust exposure of workers in the remaining plants depended on the time spent in the dusty areas. In five of the plants surveyed, Bureau tests showed that in some areas worker exposures could exceed Federal dust limits in less than 2 hours.

Jan 1, 1988

By P. Nelson, R. O’Connell, J. Rostami

Tunnel boring machine (TBM) system utilization is a critical factor for predicting machine performance. The process of estimating machine performance, including rate of penetration (ROP) and machine utilization (U) must incorporate an understanding of site geology, TBM specifications and site management. The study herein presents a preliminary analysis of the different activity time and downtime components from hard rock TBMs at two project sites to evaluate their impact on machine utilization. A comparison of crew experience, first between shifts and then between projects is included to analyze its effect on utilization and downtime. This work presents the sensitivity of the utilization factor to selected activities in the projects and the impact of geology and site set-up/logistics on machine performance.

Jun 13, 2021

By G. Ferrara

During several years of operation in Europe, South Africa and other countries, the Tri-Flo has demonstrated to represent a substantial improvement of the dense medium dynamic separation systems. The reasons are: (1) high sharpness separation due to the multistage system and the application of new concepts in designing the regeneration circuit and controlling the medium rheology; (2) the possibility of performing two cuts at different densities using a since separation device and a single regeneration circuit. The paper discusses in detail the above mentioned points, with particular reference to the multistage technology, based on the circuit analysis theory, and to the control of the medium rheology based on recent work in the modelling, and simulation of the rheological behavior of dense suspensions.

Jan 1, 1993

By R. Wisniewski

Every underground coal mine in the United States must deploy and operate a wireless communication and tracking system. This paper addresses the reliability and availability of an installed tracking system and the communications infrastructure that supports it. A particular interest is the requirements for the systems to operate continuously without failure after a mine disaster for 96 hours, and the requirements in the MINER Act for the tracking systems to be ?calculated to be serviceable? and the communications systems ?redundancy?. These requirements imply a certain reliability and availability. This paper describes a quantitative way to assess these systems requirements, using the tools that are available and commonly used by the Reliability, Maintainability, & Availability community.

Feb 23, 2014