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By M. Deul

For the first half of the 21st Century the USA will rely on the same mix of fuels as for the past 50 years: Petroleum will cost more and availability will decline as developing nations modernize. Increased use of natural gas for electric power generation will result in severe stress on gas supply. Coal will be the fuel of last resort. More than half the petroleum used is imported, about the same amount as used for transportation. Only coal can provide relief by fueling railroads through electrification while encouraging ‘piggy-back’ trailer haulage, co-generation for manufacturing and expanded passenger service.

Jan 1, 2002

By Charles H. Jacoby

The economic importance of salt domes has been recognized throughout the world primarily because of oil and gas accumulations on their flanks and, to a lesser degree, for the value of their salt and potash. Recently they have become of value as hosts for cavities used to store hydrocarbons. In the near future we believe that their main value will be as a source of geothermal energy. Although tremendous effort has been expended on the understanding of the geology and physical characteristics of the strata intruded by salt domes, relatively little energy has been exerted in the comprehension of the salt dome itself. Salt domes have long been recognized as a geological heat anomaly. With respect to other sedimentary rocks, salt is a good conductor of heat. Expressing values in 10-3 cgs units, sedimentary rocks vary from 1.0 to 8.0; metamorphic rocks from 5.2 to 8.4 and igneous rocks from 3.1 to 9.8. Rock salt in its pure form has a thermal conductivity of 17. (Gussow, 1970). Thus a salt dome (Fig. Ml) can be expected to act as a conduit bringing heat vertically from deep within the Earth's crust. This was, in part, substantiated when in 1958 a horizontal core hole was drilled from within the Avery Island Mine at the 500 foot level. The horizontal hole was started where the ambient temperature of the salt was 74° F. and drilled toward the center of the dome. At the end of this 2,000 foot hole the temperature was 90° F. thus depicting a horizontal temperature gradient of 7° F./1,000 feet. Because this core hole penetrated a shear zone connate water that appeared as a "cold spot" on the temperature gradient, the foregoing data can only be regarded as indicative.

Jan 1, 1974

A bearing isolator is a noncontact, nonwearing, permanent bearing protection device. It has a rotor and a stator, and the two are unitized, so that they do not separate from one another while in use. The rotor turns with a rotating shaft, while the stator is pressed into a bearing housing. The two components interact to keep contamination out of the bearing enclosure and the lubricant in. Bearing isolators do not require lubrication or any particular shaft finish or condition. The best bearing isolators are made of metal, usually bronze. They use a vapor-blocking feature that inhibits the free transfer of vapor contamination when the rotating equipment is cycled on and off.

Jan 1, 2004

By S. Behl

A major limitation in developing successful selective flocculation schemes is the difficulty encountered in adsorbing the polymeric flocculant only on the desired substrate. In this paper a correlation between selectivity of flocculant adsorption and separation efficiency is outlined and a potential technique to achieve selective adsorption of flocculants is discussed.

Jan 1, 1992

Reaction kinetics for gold dissolution in acid thiourea solutions were investigated using formamidine disulfide as an oxidant. For the conditions studied it appears that a surface reaction limits the rate of gold dissolution. The rate was found to be first order with respect to thiourea concentration and half order with respect to the concentration of formamidine disulfide; the apparent activation energy for the reaction was 10.40 kcal/mol (43.40 kJ/mol); and the reaction rate was independent of pH for the pH range 1.0 to 3.0.

Jan 1, 1999

By H. H. Murray

Significant changes in ownership and production of industrial clays have occurred since 2000. Clays covered in this presentation are kaolins, ball clays, smectites, (bentonite), and palygorskite (attapulgite)-sepiolite. IMERYS discontinued production of paper coating kaolins at their Cornwall operations and have expanded their kaolin production in Brazil. J. M. Huber sold their kaolin operation in Georgia to KaMin whose headquarters are in Ft. Worth, Texas. BASF purchased Engelhard?s kaolin and attapulgite operations in Georgia. ActiveMinerals purchased Southeastern Kaolin in South Carolina, Wilkinson County Kaolin in Gordon, Georgia, and Zemex Attapulgite in Quincy, Florida. Chemical Lime purchased Spinks Ball Clay Company in Paris, Tennessee. Most of the ball clays used in Italy and Eastern Europe comes from expanded operations in the Ukraine. Bentonite operations have expanded production in Wyoming and Montana because of strong demand for drilling mud, foundries, cat litter, and iron ore pelletizing. The production and exports of palygorskite in China continues to increase. Nanoclays utilizing sodium montmorillonite, palygorskite, and halloysite are actively being developed.

Jan 1, 2009

By Chee Theng

"It is not surprising that the most popular key takeaway from the Developing Diversity in Mining workshop (see box) held on the first day of the SME Arizona Conference in December was, “Have more parties!”The adage that mining professionals work hard and play hard was clearly demonstrated at the two-day conference in the JW Marriott Tucson Starr Pass Resort & Spa in Tucson, AZ. Nearly 550 participants, some of whom had left behind frigid temperatures and thick parkas in their hometowns, attended a full slate of technical sessions, shared industry experiences and knowledge, reconnected with buddies in the industry, and made strategic new contacts in the conference’s collegial environment, aided by the mild Arizona winter.To start off the technical sessions, John Mansanti, president and chief executive officer of Crystal Peak Minerals and 2017 SME president, entertained a packed lecture room with his keynote lecture on “Tariffs, Embargos, and Cartels ... Oh My! A Perspective on Potash.” Mansanti gave the audience the benefit of his more than 35 years of experience at companies including Barrick Gold, Newmont Mining Corp., Placer Dome, Freeport-McMoRan and Intrepid Potash, where he was senior vice president for operations, technology and strategy. At the luncheon, Justin Cross, general manager of Freeport-Mc- MoRan’s Bagdad operations, spoke on how the role of a leader in mining is transforming from one based on technical expertise to one based on the ability to collaborate, to lead and to adapt to changes in technologies and skill sets, in his talk on “Knowing When to Learn, When to Lead and When to Manage.”"

Feb 1, 2019

By N. Kuyucak

Uranium ores leached with sulphuric acid typically have poor dewatering properties. Applicability of controlled neutralization where gypsum precipitates as crystalline particles, improving dewatering properties of material was examined. Neutralized material was then dewatered using paste thickener to increase underflow density. The objectives are to maximize water recovery due to water scarcity and to produce suitable cemented paste fill material for optimizing underground ore recovery. Work was performed on acidic slurry samples collected after leaching but before the resin-in-pulp uranium recovery. Controlled neutralization greatly reduced volume of neutralization precipitates giving higher densities and improving the dewatering (filtration) properties. As a result it would be possible to increase the water recycled to the mill. Another benefit is that sulphate in the recycled water was reduced to saturation limit minimizing scaling of process equipment. Additional test work is needed; however, Unconfined Compressive Strength results imply that controlled neutralization increases the strength of paste fill and possibly offers opportunities towards a viable backfill option.

Jan 1, 2010

By Zhian Liang, Xiong Huang, Weixin Wu, Lifeng Cui, Zhuanhua Wei, Guoyao Li, Xiao Ni, Junrong Wang, Shuiping Zhong

ZJ 201 (modified starch) is a non-toxic, odorless, and biodegradable polymeric depressant, which selectively depressed galena in batch flotation tests while chalcopyrite was not significantly affected. In a plant trial, copper-lead separation was successful for the first time without using dichromate. Moreover, the plant process could be changed to sequential Cu-Pb flotation using ZJ 201 for higher grade lead concentrate. A copper concentrate was obtained with a Cu grade of 24.91% and a Pb grade of 5.11%, which recovered 76.6% of the copper from the original ore; a lead concentrate was also obtained with a Pb grade of 21.90% and a Cu grade of 5.31%, which recovered 52.6% of the lead. In addition to the effective copper-lead separation observed in the plant trial, another improvement observed is that gold was recovered mostly in copper concentrate, which could be sold for higher prices. Au grade reached 230.64 g/t, and its recovery reached 65.8% in the copper concentrate. Au grade in lead concentrate was only 18.90 g/t.

Aug 27, 2021

Well designed and maintained haul roads are the key to minimizing truck haulage on-road hazards and costs, as well as increasing productivity. However, practically designing and managing a haul road for optimal performance is often difficult to achieve. Poorly designed and built roads exhibit high rolling resistance - a 1% increase in road rolling resistance can typically reduce speed on ramp by as much as 10% - and on the flat by up to 26%. In the current economic climate, investment and operating decisions come under scrutiny. In the long run, this scrutiny returns improved efficiencies and leaner, healthier operations. The focus of this evolving evaluation process should and will certainly fall on haulage operations ? simply by virtue of their contribution to overall cost of operations ? often in excess of 50% of total costs for deep open-pit mines. Whilst the end result - improved efficiency and reduced cost per ton hauled ? is not in itself problematic, it is the route, or process followed to achieve these savings that needs to be carefully managed. We can be guided on this journey by our understanding of how a road design is developed, and, critically, the interplay between a good design and safe, cost efficient haulage. This paper briefly summarizes the evolution of mine haul road design, from the seminal USBM work of Kaufman and Ault in 1977, through to current geometric, structural, functional and maintenance management design components. These augmented design and management guidelines have been developed over the past decade, both in response to the requirements of mine operators for more safe and efficient haulage systems, and the truck manufacturers? requirements for a more predictable and controlled operating environment. These developments have been paralleled by the need to minimize haulage hazards, both from a health and safety perspective. Whilst improved mine haul road design does indeed reduce haulage accidents, recognition also needs to be given to human factors which are a significant contributor to haulage accidents. The human factor is the most problematic to address in a road design. It is often easier break the link between the interactive effects which may lead to accidents than trying to predict and reduce human error. These human factor interactive effects include the geometric, structural and functional design components and to prevent an accident or reduce the severity of its consequences, a road should be more accommodating to human error. The more that is known about human error, the better a road can be designed to accommodate those actions or non-standard practices that would, on a poorly designed road, invariably escalate an error into an accident.

Jan 1, 2010

By G. S. Dobby

The Cu-Au flotation cleaning circuit at Freeport Indonesia consists of three stages: two flotation column stages, in series, followed by one stage of mechanical cells. Concentrate from both column stages is combined as final concentrate. The mechanical cell stage has two parallel rows of seven Wemco 500's. The Wemco concentrate is recycled to feed of the second column stage and Wemco tails report to final tailings. This paper examines cleaner circuit performance, focusing on size-by-size performance of the individual stages and the individual mineral groups -copper sulfides, gold and in sol minerals. The recovery mechanisms of insol minerals are examined.

Jan 1, 1995

By Yi Yang, CHENGLONG XU, HAORAN LI, YALI FENG, JINRONG JU

This study presents a method for recovering valuable metals and synthesizing anhydrite from steel slag using sulfuric acid leaching and solvent extraction. The process achieved high leaching efficiencies for V, Ti, Fe, and Mg, and produced anhydrite with 93.09% purity. The leachate was further processed to separate and recover V, Ti, Fe, and Mg using selective stripping and precipitation methods, offering a sustainable approach to steel slag utilization.

Jan 22, 2022

By Harvey W. Parker

Our industry has developed to the skilled, experienced and productive industry that we now enjoy as a result of the visions of great engineers throughout history, but, in particular for their visions in the last 1 centuries. Unfortunately for our forefathers, the technology lagged so far behind that these exceptional visions could not be realized for decades, sometimes for a century. All that has changed in recent time and many bold and visionary projects can now be constructed and operated because of dramatic advances in technology. Before, say, 1950, tunnel technology developed very slowly. However, technology is now developing at such a fast rate that planners and decision makers are challenged to stay ahead. Moreover, new technology will develop during the lifetime of any project that can dramatically improve under-ground space projects. One of the best examples of this technological advancement is that of closed-face TBMs which now make tunneling feasible in previously impossible ground conditions. Since it usually takes a decade or more to plan, overcome environmental and political issues, construct, and put into service major projects, planners and designers are challenged by the changes in technology that occurs during the long time span of planning and construction. This is particularly true of large infrastructure projects such as transportation, water and wastewater systems and other major underground schemes. Also, since the serviceable life of many of these tunnels is often over one century, planners must consider not only lessons learned from the past but also what new concepts and innovations may develop over an extremely long time. These and other issues create a great challenge to planners and illustrate the great importance of careful but creative vision and flexibility during planning of long-term tunnel and underground space projects.

Jan 1, 2008

By Yuchen Wu, Jing Mei, GUOZHONG LIU, KE GAO, Songjie Tian, Jianwei Cheng, Yu Wang, Yuhang Wu, Hui Wang

The stability and integrity of protective coal pillars between the longwall working face and development roadways are greatly affected by the mining activities such as the development face advancing or retreat mining. Due to underground strata pressure, the coal pillar cracks could be further developed and then the air leakage passages (mainly cracks) could be produced greatly. The air circulation caused by the atmospheric pressure difference between the two sides of the coal pillar may also provide suitable conditions for the possible spontaneous combustion of the residual coal in the mine gob. In this paper, a typical the protective coal pillar in a Chinese coal mine is studied. The deformation and stress of coal pillars during the mining process of longwall working face are simulated by using FLAC3D. The displacement and strain of coal pillars are analyzed. Two indexes, the linear fracture rate (LFR) and area fracture rate (AFR), are introduced to characterize the development of internal cracks’ development within coal pillars. By using field measurement, the air leakage intensity distribution due to coal pillar cracks is obtained; the equation of air leakage resistance of coal pillar under the influence of mining is derived. Then, the possible location of large air leakage of coal pillar is determined, which can be used as guidelines to study the possibilities of coal spontaneous combustions happening in pillar or mine gob. The research results help to control such potential hazards in advance.

Jun 16, 2022

By J. J. Reilly

The Vesta Mines of the Jones & Laughlin Steel Corporation operate in the Pittsburgh Seam in Washington County, Pennsylvania. This seam is overlain with a drawslate, 12" to 16" in thickness, which slimes readily when wet. Because of the need for a uniformly good quality metallurgical coal, the amount of reject, together with the top and particle sizes of the raw coal feed, is a serious problem at the Vesta Preparation Plant. The Preparation Plant operates two, seven and one-quarter hour shifts per day and processes 2,100 tons per hour of raw coal feed. The third shift is, used for planned maintenance of equipment. Since the water clarification equipment is so vital in insuring a uniform product, there is no alternative but that it be in operation at all times. To insure this continuous operation,. well-planned maintenance is a necessity. For years, Plant Management has kept performance records of the various units to determine the renewal dates of vital component parts, the length of wear, the various materials used in the manufacture of the equipment, and the labor cost for renewal. These records have been of inestimable help in planning an effective maintenance program to insure continuous operation of the various units.

Jan 1, 1959

By S. J. Schatzel, J. D. Addis, V. Gangrade, L. L. Chasko, C. A. Hollerich

"A ventilation study using tracer gas was conducted at a western US coal mine. The objective of the study was to evaluate the movement of longwall face air exchanges between the face and worked-out area and to document the presence or absence of face airflow pathways between these locations. The mine operator uses a bleederless longwall ventilation system with a back return and a blowing mine ventilation system. The study was conducted on an active panel and included both underground and surface monitoring sites. The study used sulfur hexafluoride (SF6) released as a slug on the longwall face and in the front of the gob inby the face. The velocity of the tracer gas movement in the gob was 0.019 m/s (3.7 fpm). The rate of movement for the overall tracer gas slug averaged about 0.0091 m/s (1.8 fpm). A separate tracer gas test initiated with the release of SF6 into the legs of the first shield showed the existence of more than one pathway of face air in the general direction from the headgate towards the tailgate corner. Maintaining adequate ventilation air on longwall faces is important for worker safety and for the dilution of methane emitted from the face and caved gob. A more detailed characterization of longwall system air and gas movement allows a mine to better assess its ventilation design for controlling gas on the face and in the gob. INTRODUCTION During a series of stakeholder meetings, a near unanimous concern was expressed related to maintenance of effective ventilation airflow on longwall faces. There was a strong interest expressed regarding the impacts of face length and caving characteristics on the ability to maintain adequate face airflow levels. This study seeks to understand and improve a mine operator’s ability to monitor and control ventilation and methane concentrations across the longwall face by assessing airflow variations in terms of roof caving characteristics and face length. National Institute for Occupational Safety and Health (NIOSH) researchers seek to identify flow paths of ventilation airflow on longwall panels with variations in roof caving characteristics and longwall face lengths. The project research aims to develop an understanding of the role of gas dynamics in variable broken rock, interactions with ventilation airflow and methane concentrations across the longwall face area. The research also addresses continuous ventilation monitoring along the shield line to provide early detection of gas exchanges between face and gob, and thus improve a mine operator’s ability to monitor and control ventilation and methane concentrations around the face. In the context of this paper, the longwall gob refers to the pillared area behind the shields. This work reports on results from one project task to conduct field based research using a tracer gas to describe face air and gob area gas movement in a bleederless longwall ventilation system that incorporated a back return."

Jan 1, 2017

By G. Davis

Mineral properties and mineral firms often trade at a market value that is significantly greater than the value indicated by discounted cash flow (DCF) techniques. A possible explanation is that DCF analysis does not consider the value derived from managerial flexibility. Presumably, then, at least some of the difference between DCF value and market value is due to managerial flexibility. This paper surveys the recent attempts to empirically quantify the value of managerial flexibility using option pricing theory. The results indicate that managerial flexibility, at least as measured by the option pricing methodology, falls well short of explaining the gap between DCF value and market value.

Jan 1, 1995

By O. J. R. Baena, I. C. Sánchez, J. L. G. Guzmán

Frontino, a municipality in western Antioquia, Colombia, has more than 200 years of mining tradition. Currently, mining activities are carried out for lode gold using subway tunnels, where the grinding of the material is done in "cocos", whose energy depends on internal combustion engines and ACPM, environmentally polluting and inefficient methods. In accordance with the Sustainable Development Goals as an initiative developed by the UN, different mining methodologies that are aligned with these are constantly being analyzed. This study proposes to eliminate the use of hydrocarbons in artisanal mining, mainly promoting Sustainable Development Goals 7, 9, 11, 12, and 13. This will be achieved through an energy transition to renewable energy sources that take advantage of the topography and water resources of the area, providing advantages to the communities that live there, such as lighting, electricity for cooking, ventilation for mines, etc

Mar 2, 2022

By Chiranjibi Santi, Amit Kumar Gorai, VIVEK KUMAR HIMANSHU

Air overpressure (AOp) and peak particle velocity (PPV) are the most undesirable effects of blasting in mines. It is an urgent need to design a predictor model for AOp and PPV for universal applications to minimize environmental effects and damages that occur due to blasting. The present study attempts to design an artificial neural network (ANN) model for the prediction of AOp and PPV in different conditions. In this study, the blast design parameters (number of holes, depth of the blast hole, stemming length, spacing, burden, distance of vibration monitoring location from the blast site, charge weight per delay) of two active mines (coal and iron ore) are considered in four different conditions for training and testing of the model for the prediction of AOp and PPV. The model was trained and tested in four different combinations of data (trained using data of one mine and tested using data of another mine, trained and tested using data of coal mine, trained and tested using data of an iron ore mine, trained and tested using combined data of both the mines) for examining the applicability in different conditions. The results indicate that R2 values are ranged from 0.886 to 0.908 and 0.8728 to 0.8959, respectively, in the prediction of PPV and AOp. A comparative study of the performances of the developed model with the other empirical model is also demonstrated. For this, the site constants of different empirical models were estimated individually for both the mines. The study results indicated that the ANN model performs much better than all the empirical models. It can be inferred from the results that blast vibration cannot be accurately predicted only from charge per delay and distance from the blast hole. The ANN model was considered many other factors and thus can predict the vibration level more accurately.

Jul 30, 2021

By JÖRG DEHNERT, PETER WINDISCH, Bernd Schönherrt, JENS STOPP

The Quick-Erect Stopping System (QESS) offers a new way of reducing the radon exposures of miners in Germany, especially during remediation work in old mines. The QESS is a light-weight, modular, and reusable construction kit of interlocking telescopic aluminum tubes, radon-proof foil, and expanding foam. It is designed to seal off radon-rich parts of galleries within only a few minutes. Originally, the QESS was developed to protect miners against radon exposures. Then, the QESS found the attention of several mine rescue teams at a German mining conference. The Student Mine Rescue of the Technical University Bergakademie Freiberg and the Wismut Mine Rescue carried out firstmine rescue drills in Freiberg and Schlema. Additionally, a mine rescue drill was carried out by the Front Range Mine Rescue in the Edgar Experimental Mine of the Colorado School of Mines. These drills helped to improve the systemand highlighted its potential for mine rescue operations. Now, the QESS is wellsuited for small-scale mining. The QESS can be used to seal off galleries in only a few minutes to both protect miners fromradon exposures and to support mine rescue operations. Moreover, the QESS was also successfully used in ventilation experiments.

Jul 23, 2020