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By J. R. Allen

Environmental laws and regulations have proliferated over the last two decades. 1/ Within the last year, Congress has dramatically expanded the scope of the Superfund program 2/ and has enacted significant new amendments to the Clean Water Act.3/ In addition, EPA has shown no signs of slackening the pace at which it promulgates new regulations to implement statutory programs. The agency projects that over the next few years it will issue approximately 275 new regulations under the statutes it implements. 4/

Jan 1, 1988

By Jr. Neudecker

Rock melting technology can provide in-situ glass liners in nuclear waste package emplacement holes to reduce permeability and increase borehole stability. Reduction of permeability would reduce the time and probability of groundwater contacting the waste packages. In-creasing the stability of the storage boreholes would enhance the retrievability of the nuclear waste packages. The rock melting hole forming technology has already been tested in volcanic tuff similar to the geology at the proposed nuclear waste repository at Yucca Mountain, Nevada.

Jan 1, 1989

By B. Li

"The spontaneous combustion of coal storage pile(Gangue Hill) is one of the seriously threat encountered in coal mining and storage. The dynamic accumulation of internal heat in coal storage pile(Gangue Hill) provides continuous heat-source for coal spontaneous combustion. Combined with the features and characteristics of coal pile storage, a technology of heat pipe(HP) is applied to enhance heat transfer. In order to prevent spontaneous combustion of coal storage piles (hillock) due to regeneration, a method using heat pipes to destroy the heat preservation conditions of coal storage pile(Gangue Hill) is proposed, which reduces the risk of coal spontaneous combustion and prevents coal fire. A theoretical model of Coal-Thermosyphon has set up to analysis the radius of cooling effect area quantitatively. An experimental equipment of the heat transferring in a set of heat pipe, which used to study the influence on coal pile temperature distribution, has been designed. Results show, the heat pipe has a significant effect on inhibiting the coal spontaneous combustion process by destroy the heat preservation conditions of the coal. Under the experimental conditions, the most obvious coal temperature decline appears at radius 20.0mm around the pipe, dropped from 45.8? to 32.5?, a decline of 29%; the coal pile temperature at radius 420mm from 12.9? to 12.4?, a decline of 3.87%. And the research offers an effective and new approach in its application and promotion for preventing and controlling in coal spontaneous combustion.INTRODUCTION China is one of a few countries which utilize coal as the major source of energy in the world, and is the one whose characteristic of energy structure is rich coal, deficient oil and lean gas. Relatively speaking, China is abundance in mineral resources. The coal, which is the fundamental resource in the process of industrialization, is the main energy in china. Thus China cannot alter the situation of coal consumption dominated a leading role in its energy structure in near term.A massive of coal gangue would be produced every year in China with the mining activities. And it’s estimated that almost 360 million tons gangue were dumped in 2003, accounting for 10 percent of the whole coal production. Huge numbers of coal waste piles have more than 2,600 seats, which cover an area of over 12,000 hectares. Worse more, the coal gangue still has an annual growth rate of 100 million tons. Toxic smokes and greenhouse gases are discharged directly and prolongly into the atmosphere due to coal gangue spontaneous combustion. Even worse, waste dump explosion cause massive losses and are able to endanger the safety of workers. For example, one waste dump of the NO.4 Mine of Pingdingshan Coal Group Co., Ltd. occurred twice of explosions in 2005, and about 3.13 million tons of waste rocks were thrown within the range from 100 to 300 meters, eight people were killed and 122 rescuers and miners were burned, and economic losses were estimated more than 3,000 million."

Jan 1, 2015

By Ramarao Inguva

Feasibility studies being conducted to investigate the use of electromagnetic methods for insitu volumetric heating of oil shales will be discussed. A two dimensional numerical model which describes eletromagnetic heating of oil shales is outlines. The model includes equations for temperature, pressure, saturations, chemical reactions, mass conservation, and source terms. The gases are all assumed to form one bulk species and the oil is assumed to remain in liquid form. The chemical reactions include pryolysis of kerogen and char, release of bound water, coking, and decomposition if carbonates. Porosity and permeability are dynamic functions of the organic materials. Calibration of the model is accomplished by comparison of the model results with experimental data obtained by IITRI. Nonlinear relationships for viscosity, thermal properties, and source terms and used as inputs to the model. A finite difference approximation to the differential equations is derived and solved using Newton's iteration technique. For the cases studied the solutions are quite stable. Numerical resultes are included and a preliminary study of the optimization of the heating process is presented.

Jan 1, 1984

By V. Izaxon

Current practice in mining frozen, underground placers is to support the mine openings by leaving remnant pillars, which are kept frozen to maintain their stability. These pillars may be partially extracted depending on mining conditions, but this practice may be risky, and roof falls are common. Instead of allowing the mined-out areas to cave, the extracted entries could be filled with waste material, which would then be frozen, using cold ventilation air. A finite difference model for analyzing the effects of various parameters on the freezing of backfill in underground mines in the Arctic has been developed and tested. The model also accounts for properties unique to a frozen rock mass, including those that change with temperature. Examination of the characteristics of ice-cemented mining waste materials as backfill indicates that with proper engineering control, a backfill system can be designed for use in production mines. The system will allow increased extraction ratio while maintaining the stability of underground openings with minimum heat impact on the surroundings. These simulated results establish the relationships among the strength, the temperature, and the freezing characteristics of a given material. When coupled with site observations these relationships will facilitate the optimal design of ore pillar recovery methods.

Jan 1, 2004

By Sean E. Armstrong, Deepak Malhotra

The current trend in gold ore processing is the development of lower grade or highly refractory deposits. The perplexity of treating low grade oxidized ores has been adequately addressed by heap leach technology. However, refractory gold ores are very difficult to positively characterize the gold association within the mineral matrix. Gold accompanied with refractory sulfitlc or carbonaceous mineralization can often be sub­micron In size and occur interstitially. Mineralogical examination of these ores Is difficult, expensive, and occasionally Inconclusive. Hence, the metallurgist Is given little information for the selection of processing alternatives. The purpose of this paper Is to demonstrate the use of diagnostic leach procedures to assist the metallurgist' s decision-making process to solve some of these problems. By sequentially liberating and/or leaching gold associated with specific minerals, the amount of recoverable gold in each stage can be determined. Through careful interpretation of the results obtained by diagnostic leaching, the metallurgist can devise a flowsheet for treating the ore or solve a problem at an existing plant

Jan 1, 1992

By Silvano Perla

Peabody Western Coal Co. operates two mines in northern Arizona. The Black Mesa and Kayenta coal mines are unique for several reasons. They both have only two customers: Southern California Edison’s Mohave generating station near Laughlin, NV and the Navajo generating station near Page, AZ. Both mines are close together. Between the two, they ship nearly 11 Mt/a (12 million stpy) of coal. Material is shipped to the power stations in two ways. This first is a 440- km-long (273-mile-long) underground slurry pipeline, the longest in the world. The second is an 11 -km-long (17-mile- long) long conveyor to four storage silos. Product is then shipped by train from the storage silos to the plant sites. Another factor makes these mines unusual. They are both situated in the middle of the 68,795km2 (17 million- acre) Navajo Reservation, home to the Navajo Nation and Hopi Tribe members. Nearly 90% of the Black Mesa and Kayentamines’ 850 employees are tribe members. Peabody Western Coal is the United States’ largest private employer of Native Americans.

Jan 1, 1995

By Annan Cook

Cyprus Metals' Sierrita mine is located in the Pima Mining District, Pima County, Arizona (Fig. 1), which is one of the largest known porphyry copper districts. The ore body is part of a large mineralized system that includes Cyprus' adjoining Esperanza mine. The copper and molybdenum grades being mined at Sierrita make it one of the two lowest grade porphyry copper mines in the world Mineral production from the district was first recorded in 1876. Copper from replacement deposits in carbonate rocks and copper¬-lead-zinc from veins in volcanic rocks were mined from several deposits. However, it was not until 1957 that the district commenced to become a major copper producer with the beginning of production from the Pima mine, which was the first open pit operation. Since that time, seven other open pit mines have come into production. Because of the variable copper prices and high operating costs, not all of the mines are operating today. A map of certain outcrops, plutons, and open pits, as well as older underground mining operations, in the Pima district is shown in Fig. 2.

Jan 1, 1991

By T. C. Rao, Vanangamudi. M., J. P. Barnwal

Experiments were carried out on 76 mm laboratory heavy medium cyclone treating -2.0 t 0.5 mm coal and on two 600 mm industrial heavy medium cyclones treating coal in the size range -13.0 t 0.5 mm. The variables studied were spigot diameter and feed medium gravity. The generalised distribution curve for the separation of coal in these heavy medium cyclones has been defined by the equation [ ] The specific gravity of separation SG has been found to increase linearly with increase in feed medium, gravity (SGf). The relationship for SG of industrial cyclone is given as 50 SG = -6.801 t 6.463 SGf t 0.0327 Spig 50 -0.02625 SGf. Spig. Further, the probable error for the separation has been found to be linearly related to (SG50 - SGf ) according to the equation [ ] The model equations developed have been used to select appropriate levels of operating conditions to achieve an increase in the yield by about 2 to 4% without affecting the quality of the product.

Jan 1, 1990

By Thomas H. Koenning, James R. Boulton

The coal mined by Cyprus at the Shoshone mine near Hanna, WY is highly susceptible to spontaneous combustion. Spontaneous heatings have occurred in the gob of several of the longwall panels and, in some cases, following roof falls. Prevention and detection methods have evolved over the years as more has been learned about the occurrences. Seal design and construction have progressed to reduce air leakage into the gob. Pressure balancing has been successful as a supplement to good workmanship in reducing leakage. Early heating detection has improved as knowledge has been gained. Prior methods of detection relied upon thermocouples detecting a temperature change. Later a gas chromatograph was used to analyze gob gas samples. Initially the products of combustion (POC) were relied upon for detection. Most recently, lack of oxygen depletion in the gob has been used as an early warning of problems. Examples are presented to illustrate the evolution of spontaneous combustion control at the Cyprus Shoshone coal mine. Methods have been developed which minimize the oxygen concentration in the gob and reduce the potential for spontaneous combustion.

Jan 1, 1997

By G. Atesok, M. S. Celik, G. Onal, I. Yildirim

A new coarse cleaning device, the Stripa, has been developed for processing of coal in the size range of -100+10 mm. The Stripa is an auotogenous heavy medium separator originally developed for processing of iron ores. Although it has been employed in concentrating ores such as chromite, it has not been applied in coal cleaning. In this study, a pilot plant scale modified Stripa and its counterpart alternative, a diaphragm jig, are compared using subbituminous and lignitic coals. The separation performance of the Stripa and the diaphragm jig has been established in the light of washability properties of the coal samples. Comparison of the performance of the Stripa with that of the jig indicates that the Stripa can be used in coal preparation circuits as an alternative to jigs in the size range of -100+10 mm. Simplicity, low initial investment, and low operating and maintenance costs make the Stripa a plausible candidate for coarse coal cleaning. More importantly, Stripa due to its short residence time, has a superior capacity over jig.

Jan 1, 1995

By Prasad Kummarapurugu, Maija Teijonsalo, Sirkka-Liisa Jamsa-Jounela

There has been a significant progress in the use of mathematical modeling and simulation in the minerals industry in the last decade. Process models have moved from academic world to important industrial tools. This paper reviews the status of mineral processing simulators and recent progress in simulator development and applications is discussed. The simulation for process design and optimisation is now an established technique, as evidenced by its increasing use of practising engineers through commercially available simulator software. The paper presents a systematic approach to the process study procedure for the control system development, clarified by practical case examples calculated by SimCon - a novel steady-state simulator for mineral processes. Examples of the application of SimCon in drawing flowsheets, calculating mass balances and making simulations for grinding and flotation processes are presented. At the end of the paper, the state-of-the-art and the future of computer-aided pro- cess study at mineral processing plants is discussed. Keywords: Simulators, modelling, object oriented programming, computer aided control system design

Jan 1, 1996

By J. P. Barbosa, R. V. V. Araújo, R. B. E. Trindade

Bromide stabilizes the auric or aurous ion by forming a stable complex in acidic aqueous solution. The oxidizing agent normally used for the process is bromine, which is a corrosive liquid with high vapour pressure. This is, in fact, the main reason why it has not found acceptance yet as an industrial oxidant for gold. Ferric ion with hydrogen peroxide and/or sodium hypochlorite have already proved to be effective oxidants for the dissolution of gold from a rotating disc in a bromide-containing aqueous solution. In the present work, preliminary tests with four selected ore samples were tested to evaluate the dissolution of gold with the same system already tested with the rotating disc (Br-/Fe3+/H2o2/NaCIO). Compared to the conventional cyanidation, results were superior in one instance only. The major obstacle seems to be the maintenance of a suitable potential to allow the complex formation. However, the studied system may be interesting, is in some situations it may yield better results than conventional cyanidation; therefore, further investigation seems to be worth doing.

Jan 1, 1995

By Toshio Fujiwara, Sumikichi Ito, Masao Kitamura

The Tennohji-Benten Giant Trunk Sewer Project has been under construction since 1974 in the eastern part of Osaka, the second largest city in Japan. The entire project is divided into 7 blocks, some of which have already been completed. This 8.8-km sewer tunnel, being driven through a densely populated area, was planned to be constructed by the shield tunneling method. This paper described shield tunneling performances and ground behaviors during the construction of Blocks 2 and 3. An earth pressure shield (dia., 6,750 mm) was employed in Block 3 tunneling. The ground was generally soft and the cover over the tunnel varied from 13 m to only 4.5 m, so that a considerable amount of chemicals was injected to stabilize the ground. A hand-digging type shield (dia., 7,250 mm) was used in Block 2 tunneling under compressed air. For 85 m of the total length of 1.6 km, the soil at the face was extremely soft, and therefore, the ground freezing method was additionally employed.

Jan 1, 1981

By B. K. Mishra, S. P. Mehrotra, Anand Katti

Particle-size monitoring has become routine plant prac¬tice, and on-line measurement techniques have facilitated the proper control and monitoring of particle size. In this paper, the progress on an on-line size measurement technique using a y-ray source is discussed. The tray is emitted from a nucleonic density gauge (NDG) that serves as a slurry den¬sity-measurement device. This unit is calibrated and tested to predict the slurry density. Batch experiments were conducted to study the variation in slurry density of different types of ores, namely, quartz, bauxite and hematite. This data, in turn, is used to predict the size distribution of the solid particulate material making up the slurry. To calculate this size distribu¬tion from the slurry density, the theory of incremental sedi¬mentation is used. Experimental results show that the pre¬dicted size distribution compares well with the actual size distribution, as measured by the Andreasen pipette technique. Finally, a simplified scheme is proposed to monitor on-line size distribution using the nucleonic density gauge

Jan 1, 2000

By S. Mason

Many organizations are realizing that continual improvement in health and safety relies on addressing the potential for various forms of human error. Of these, rule violations are often the most frequent form associated with accidents. These occur when an individual (or individuals) deliberately contravenes established and known safety rules. They have been associated with up to 90% of the accidents and other incidents in some industries, and yet they rarely receive the systematic attention they deserve in the promotion of safety. This paper presents underlying motives that cause violations. These can vary significantly from mine to mine and from job to job. Managers need some measure of the attitudes of the violators to determine the underlying motives behind the violations if they are to determine effective strategies for promoting safe behavior. Questionnaires form the starting point to address attitudes and the motives behind rule violations. The choice of the most suitable questionnaire, how- ever, will vary from organization to organization. Guidelines on the choice of questionnaire are offered.

Jan 1, 2000

By R. Frenette, A. W. Mo, H. A. Hamza

Fine particles present major technical and economic problems to those who deal with solid/liquid separation processes. In the coal industry the problem is compounded by the large amounts of produced fines such as those present in Western Canadian coals. Flocculants in the form of high molecular weight water soluble polymers are commonly considered an effective solution for the enhancement of the separation process. These reagents are relatively expensive especially when considering a low-price commodity such as coal. Optimization of the use of these reagents is therefore an operational necessity. Six polymers were evaluated as to their effectiveness in flocculating a fine coal tailing. Results were compared with those for a reference flocculant, in-use at that time in the washery. It was shown that, in general, flocculants significantly improve the solid/liquid separation process. The ranking of the flocculants as to their effectiveness in settling and filtration indicated that the best flocculants for settling were not necessarily the most effective for filtration. Flocculants that showed the best filtration improvement were generally cationic and those best for settling were anionic.

Jan 1, 1988

By Jianliang Li, Xi Peng, Guorong Lu

This paper describes a wind tunnel modelling study on airflow and pollutant concentration in a large open pit mine located in southern China. A 1:1000 scale model of the surface mine was fabricated and placed in a wind tunnel. Airflow velocity in the test section of the wind tunnel can be continuously adjusted from 0.3 m/s to 6.0 m/s. In this study, both the present pit condition and the projected final pit condition were modelled. Airflow direction and velocity profiles were obtained. The impact of wind direction and velocity on airflow was also studied. The pollutant concentration distribution in the open pit was simulated using smoke, and a distribution profile was obtained. Respirable dust concentrations at the mine site were measured, then its concentrations at the projected final pit condition were estimated using the obtained pollutant concentration distribution profile. Under normal meteorological conditions, it is expected that the respirable dust concentration for the final pit should not exceed the government standard. Key Words: wind tunnel modelling, open pit, surface mining, scale model, mine ventilation, airflow profile, point source.

Jan 1, 1993

By Edward Donovan, Bryan Knott, R. E. Melley, O&apos

South Bulga Colliery, located near Singleton in the Hunter Valley region of Australia, began longwall production in late 1994. The mining conditions there are conducive to high productivity with good roof conditions and a shallow seam with production areas located close to the portal. When the longwall was commissioned, the low capacity and availability of the conveyor system greatly curtailed the mine's productivity. A number of changes were made to the conveyor system culminating in a drive change out to improve the system. Using South Bulga as a case study, this paper aims to demonstrate the absolute necessity of a reliable, high performance conveyor system for the viability of a mine, and some of the factors that are needed to ensure a conveyor system performs as intended. These factors include a thorough understanding of the individual components and how they influence and interact with each other; a system design that is tolerant of variations in component performance and the necessity of robust and reliable communications and PLC programming.

Jan 1, 1996

By Gordon M. Elliott

Health risk underlies all of today's environmental regulations. Mine Manager's are no strangers to risk, but risk in the context of mine management is not the same as risk in the context of environmental regulation. One of the risks facing the mine manager is whether the mining operations meet environmental compliance standards. These standards are defined in terms of the frequency of occurrence of adverse health effects in an exposed population (i.e., health risk). Demonstration of compliance necessarily involves mathematical modelling and selection of values for input variables. What is not immediately apparent is that the method of estimating the human health risk has a significant influence on remedy selection and the amount of money spent at suspected contaminated sites. Using a hypothetical, mining-related example, this paper illustrates the disassociation between the current deterministic approach to health risk assessment and cost-effective decision making. This paper also illustrates how the probabilistic approach to health risk assessment provides a more realistic characterization of health risk and enables mine managers to identify cost-effective remedial strategies for the site.

Jan 1, 1992