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By I. Longson

As a longwall coalface advances a caved goaf or waste region is left behind. Air flow takes place through this permeable goaf due to the pressure differentials existing across it and en route this leakage air picks up both heat and moisture. A marked deterioration in climatic conditions occurs in the face area at all points downstream of where this leakage air rejoins the main air-stream. This goaf heat source can make a very significant contribution, typically 30-40% to the rate of total heat pickup on an advancing UK longwall coalface with a VST of 40°C and hence on the climatic conditions that prevail at the return end and in the return gate of the face. The magnitude of the rate of heat collection from the goaf depends on a number of factors but it has been established that it is particularly influenced by the prevailing virgin rock temperature and the total flow rate of the leakage air. This paper proposes a model for the goaf based on a packed bed analogy and other assumptions required in order to evaluate the rate of heat pickup are identified. The outlet condition of the leakage air predicted by the model have been shown to correlate with underground measurements taken for a range of different production patterns with the face cutter at various locations on the face. The sensitivity of these predictions to variations in the input data has been tested and is commented on. At this stage of the development the capabilities and predictive limitations of the model are discussed. Further areas of investigation are suggested in order to improve the predictive ability and to extend the versatility of the model.

Jan 1, 1989

By Peter Zhang, Daniel Su, Bo Hyun Kim

Shale gas wells drilled in longwall chain pillars are influenced by longwall mining. Longwall mining on each side of the chain pillars can create overburden movements and induce deformations in gas well casings. If the deformations result in a casing breach, intrusive shale gas could leak into the longwall mine with serious safety consequences. This study concerns five shale gas wells in the chain pillars between two adjacent longwall panels in the Pittsburgh coal seam under a cover depth of 670 ft and a mining height of 7 ft. The gas wells were constructed with typical casing design, but a casing cementing alternative with uncemented production casings was practiced. Four production casings were uncemented, and one production casing was unintentionally cemented with good quality cement to a 535-ft depth and low-quality cement stringers from a 444- to 535-ft depth. The longwall faces passed by the shale gas wells as each adjacent longwall panel retreated. Production casings were surveyed by a multi-finger caliper after each panel was mined. No deformation was detected in the four uncemented production casings, but small deformations were detected in the partially cemented production casing. The maximum measured deformation in the cemented production casing was 0.05 in. after first panel mining and 0.06 in. after second panel mining. The casing deformations were also predicted by the FLAC3D model set up on site-specific overburden geology. The predicted deformations were in good agreement with the measurements in terms of deformation locations and magnitudes. All five shale gas wells resumed normal production after being temporarily plugged during the period of mine-by. This study provides a successful demonstration of the effectiveness of a casing cementing alternative for decoupling production and intermediate casing, and thus minimizing the influence of longwall mining in the shale gas wells drilled through longwall chain pillars.

Jul 1, 2023

By Gregory Witte

This paper will explore the technology behind and applications of smart motor control centers (MCCs) being used today in mineral processing facilities. The two technologies to be discussed are solid-state motor controllers that can be installed in MCCs and the complementary digital communication networks that can transmit operational parameters of the solid-state devices to the supervisory system. The toughness and reliability of solid-state technologies have led to a dramatic increase in their usage throughout the mining industry. Products such as solid-state motor protectors, controllers, and variable frequency drives have demonstrated greater flexibility and performance in a variety of applications than their electromechanical and mechanical counterparts. The three key trends apparent in the solid-state devices are: 1. A shift to smaller, smarter, more integrated devices, which allows a single solid-state device to serve the purpose of multiple electromechanical devices but in a much smaller form factor. 2. Distribution of control logic in motor control devices rather than conveyed through a hard wired connection to a central automation system. 3. Embedded network communication that allows supervisory systems to have an expanded view into critical loads and sensors. In applications, the use of smart actuators and sensors with integral local intelligence and communication allow a supervisory controller to send high level commands and let the smart device coordinate its own work The ability of smart field devices to return noncontrolled, nonpoled information opens a whole array of new capabilities for preventive maintenance and diagnostics and forms the basis for an effective motor management program. The smart motor control devices this paper will explore are the smart motor protectors (SMP), smart motor controllers (SMC), and variable frequency drives (VFD).

Jan 1, 2000

By R. E. Brewer

Phelps Dodge Mining Company (Phelps Dodge) is operating a pressure leach vessel (PLV) for copper concentrates at the Bagdad Mine facility in Arizona. This single PLV unit was engineered and constructed based on continuous laboratory testing, reaction chemistry and kinetics, and available pressure vessel technology. The challenge of designing for optimum process retention time, agitation, oxygen mass transfer, temperature and pressure will be reviewed in this paper. The PLV interior lining, agitation equipment and compartment configuration chosen for the PLV will also be reviewed.

Jan 1, 2004

By J. Steven Whisler

Corporate managers are facing increasingly demanding challenges as they seek to ensure compliance with environmental laws. Management also must deal with new liabilities created by environmental laws. These laws provide both private groups and governmental agencies with access to the courts to seek penalties, compliance orders, cleanups, or to forestall developments that could affect ecosystems. Environmental laws and liabilities are also affecting commercial transactions, including the availability of financing. Corporate managers must develop new and innovative methods to address these challenges in order to assure both sustainable industrial growth and stewardship of the environment.

Jan 1, 1991

By Anthony D. Hammond

INTRODUCTION A two-dimensional approach for modeling narrow-vein deposits using the TECHBASE® software was implemented at Sunshine Mining for its use in the evaluation of mineral properties. This 2-D approach prevents the overestimation of high-grade tons typically associated with the use of fixed 3-D blocks and reduces the size of the model in computer memory. The method consists of constructing a two-dimensional model oriented along the average plane of the mineralized structure. This approach works well for single, multiple and intersecting veins with the condition that each vein is roughly planar with variation in dip or strike less than 30" in order to maintain a reasonable resolution in the process of projecting data onto a plane (Figure 1). Also, a precise identification of the hanging-wall and foot-wall location is critical in ensuring an accurate representation of the vein. By using various modeling techniques, the two-dimensional model estimates metal content, thickness, tonnage, economic and dilution parameters which will be ultimately used in the identification of minable reserves. The following is a generic description of the steps involved in modeling a steeply dipping vein. DATA ENTRY A typical project database consists of drillhole coordinates, survey information, assay data and any other quantitative or qualitative data. This database can be created inside the software or imported from any spreadsheet. TECHBASE® utilizes the concept of "fields" and "records" (columns and rows) for storing data. The use of "calculated fields" enables the user to expand on the manipulation of the database with minimum memory requirements. Another important feature of TECHBASE® is the ability to replicate the structure and format of the "tables" for its use in another project and the capability of running a series of repetitive tasks by means of batch and "runlog" files.

Jan 1, 1998

By B. Govindarajan, T. C. Rao

A simulation of batch-flotation experiments was carried out using a simple empirical model to identify the process parameters that would give maximum yield at any given ash level. The relationship between the maximum yield values and the percentage ash-reduction ratio (ARR) has shown two regions where the collector and the frother dosages have individual influences on the flotation performance. Based on this observation, a simple "selection-criterion diagram" is proposed. This diagram can he used to select the process parameters to achieve maximum yield, for a given ash content of the concentrate and at any given flotation period.

Jan 1, 1997

By Andrew M. Garvie, William W. Plotnikoff, Eugenia Y. Kuo

Water infiltrating the surface of waste rock dumps transports pollutants into the environment. Lysimeters have been used to quantify the infiltration rate. To date their design has been guided by modeling under steady-state conditions. Recently a two-dimensional finite element code has been developed to model the response of lysimeters to time-dependent infiltration rates. It was used to investigate the response of lysimeters installed in a waste rock dump and subject to a monsoonal rainfall pattern. The results are presented and compared with field data.

Jan 1, 2000

By Y. Lin

The objectives of this investigation were to study the zeta potential characteristics of a Powder River Basin coal in water and to study the effects of zeta potential on the agglomeration of coal particles. The electrokinetic measurements show that the zeta potential of the coal is dependent on pH, temperature, coal concentration and contact time with water. The effects of various additives for changing the zeta potential of the coal were also evaluated. It was found that the strength of the coal agglomerates is increased when the zeta potential diminishes. Neutralizing the zeta potential enhances agglomeration. Therefore, it is important to control the zeta potential of coal to achieve optimum performance in coal-particle agglomeration.

Jan 1, 1997

By Vas Choudhry, Randhir Sehgal

Conventional clean coal technologies which consist of coarse coal cleaning by gravity methods and treatment of natural fines by flotation can only remove a portion of the pyritic sulfur and ash in the coal. Higher (+90%) pyritic sulfur rejection is attainable when coals are ground to ultrafine sizes to enhance liberation of the mineral matter and then cleaned. However, cleaning of coal at very fine sizes poses a number of unsolved problems, the chief one being the loss of cleaning efficiency. This, of course, means that liberation of pyrites does not always equal its rejection. In addition, the dewatering of fine- cleaned coal, and its handling, transportation, and acceptability to the utility industry a1 so pose considerable technical and economic problems, especially when compared to the FGD alternative. This paper addresses some of the critical issues involved in the cleaning of ultrafine coal s.

Jan 1, 1989

By Abdullah Arik

An ore reserve block model is the basis for various decisions in mine development and production. The block model is initially built using the information from the drillhole data only. Once the mine is put in operation, the information from the blasthole data becomes available. Since the spacing of the blastholes are much closer than the exploration drillholes, the blasthole data gathered from the mine over the years become quite extensive containing valuable information about the deposit. In practice, the information from the blastholes is the basis of determining the ore and waste boundaries between and within mining blocks. In an ore reserve model, the valuation of blocks on and close to the pit face can obviously be improved by using blasthole data from neat by drilled and mined-out blocks in addition to using the widely spaced drillhole data. The ideal basis on which to integrate blasthole and drillhole data is to use cokriging.

Jan 1, 1996

More than 100,000 people from 110 countries involved in the construction aggregates and ready mix concrete industries are expected to attend Conexpo-Conlagg '99 in Las Vegas, NV March 23-27. The exhibition, the largest of its kind in the Western Hemisphere, takes place every three years. It is held at the Las Vegas Convention Center, Las Vegas Hilton Center and Pavilion. The show serves as a venue for con- tractors and others involved in aggregates construction to view the latest in equipment, technology and services. More than 1,500 exhibitors will use more than 147,200 m2 (1.6 million sq ft) of indoor and outdoor exhibit space. Attendees include presidents and company owners, sales and marketing managers, general managers and project managers. An estimated 20% of the attendees will be from outside of the United States. New for the Conexpo-Conlagg '99 show is a 3,715- m2 (40,000-sq ft) Information Technology Pavilion. This event, organized by AIEIC Systems, will showcase computer technology for the architectural, engineering and construction industries. Shown in the pavilion will be the latest developments in cost management, estimating, bidding, project management and accounting. In addition, the Information Technology Pavilion will demonstrate the latest in computer-aided design software, systems and services. Conexpo-Codagg '99 will also emphasize live demonstrations of exhibitor's products. Individual exhibitors will demonstrate their machinery so attendees can see the latest technology in action. Because the Conexpo-Codagg exposition is so large, "shows within a show" have been created to help attendees locate the products and services best suited to their interests. Seven product concentration areas will be formed. Each area houses suppliers and manufacturers of similar products or services.

Jan 1, 1999

By Morgan M. Sears

In recent years, one large mine collapse and numerous smaller bump events have resulted in a renewed interest in coal bump research. With numerical modeling, the Energy Release Rate (ERR) calculation quantifies the ?release? of the gravitational potential energy of the rock mass into the environment as mining progresses. This release of energy can occur passively in the form of heat and sound or dynamically in the form of pillar bumps or rock bursts. From the initial application of a calculated energy release rate in the deep hard-rock mines of South Africa, the ERR was found to have a significant correlation with the risk or potential of damaging coal bumps or rock bursts. In this research, an ERR calculation is incorporated into the modern LaModel program to facilitate the analysis for potential coal bumps. Initially the ERR calculations in LaModel are verified using a case study of cut sequences originally modeled using the MULSIM/NL program. Then, the ERR calculations are applied to a bump-prone mine in Southern Appalachia were a number of different pillar recovery cut sequences were used in order to minimize the risk of bumps.

Jan 1, 2009

By Yelloji M. K. Rao, P. Somasundaran

Reagents of biological origin are becoming more and more important in the field of metallurgy, especially in the areas of mineral processing and hydrometallurgy. The advantage of lower operating cost over physical and chemical processes and the capacity to operate with low grade ores make the microbial processes further attractive. In this paper, the role of microbes directly as a reagent and microbially produced reagents or secreted metabolites in mineral processing and hydrometallurgy will be discussed. Adhesion of microbes to surfaces is known to alter the hydrophobicity of minerals. Applications include surface modification to impart hydrophobicity or hydrophilicity on sulfide or non-sulfide minerals and dissolution of precious metals. Microbes can also perform the role of flocculating agents. Biosorption of toxic and heavy metal ions by microbes are finding application in treating tailing ponds. Mechanisms associated with the use for microbially produced reagents are discussed along with some recent results.

Jan 1, 1994

By R. A. Hodge, J. W. Murray

By an order of the Executive Council of the Provincial Government dated January 18, 1979, a Royal Commission was established under the Public Inquiries Act to: 1) Examine the adequacy of existing Federal and Provincial requirements for the protection of the health and safety of workers associated with exploration, mining and milling of uranium in B.C. and for the protection of the environment and of the public. 2) Receive public input on these matters. 3) Make recommendations for setting and maintaining standards for worker and public safety and for the protection of the environment as a result of the exploration for the mining and milling of uranium ores. At that time,and at the present time in British Columbia, no uranium mines were, or are, in operation. Exploration at a number of sites was under way and one deposit, the Blizzard deposit, with estimated reserves of 1.92 million tonnes containing approximately 4.74 million kilograms of U308 was at an advanced stage of exploration. With our Terms of Reference, and because of the diverse geology of the western Cordillera which could potentially host a broad variety of uranium, deposit types, the Commission was faced with the task of considering environmental and health protection necessary for the potential development of [any] kind of uranium mineralogy situated in [any] of the environments found in British Columbia. Over the past 17 months since that time, much has transpired, culminating in the February 27, 1980 Provincial Government announcement of a seven year moratorium on exploration, mining and processing of uranium coupled with the termination of our Inquiry before completion of the hearings. The Government sebsequently modified its decision to terminate the Commission completely, deciding instead to stop the hearing but allow time for the Commission to gather in the work that had been initiated

Jan 1, 1980

By Peter Fordham

A Norbridge review of 25 top mining companies highlighted financial problems for many firms. To better understand these results, Norbridge benchmarked 17 mining companies to understand the problems that companies face, the methods being used to improve performance, and the results that have been achieved. The study indicates that many mining companies in three sectors-coal metals, and non- metallic minerals-have implemented new strategies to improve performance. Many of these strategies supplement traditional initiatives with two types of process improvement efforts, facility-specific and company-wide, to help generate performance gains. The study compares the results of these strategies in each sector. INTRODUCTION imes are tough in the mining industry. Norbridge reviewed financial results of 25 top mining companies for the past 2 years-seven coal companies, twelve metals companies, and six non-metallic minerals firms.*The study found that 40% lost money in 2002, and * Coal companies include Alliance Resource Partners, Arch Coal, Consol Energy, Massey Energy, North American Coal, Peabody Energy and Westmoreland. Metals producers include Barrick Gold, Cleveland-Cliffs, Coeur d'Alene, Falconbridge, Freeport McMoran, Grupo Mexico, Inco, Newmont Mining, Noranda, Phelps Dodge, Placer Dome, and Teck Corninco. Non-metallic firms include Florida Rock, IMC Global, Martin Marietta Materials, Oglebay Norton, PotashCorp and Vulcan Materials. Information is from public sources, e.g., annual reports, company Web sites.

Jan 1, 2004

Some basic terms used in cost management and accounting include: - Cost. A sacrifice made to acquire goods or services, measured by the price paid. Technically, the sacrifice is called a cost until the benefits from the goods or services have expired, at which time the sacrifice is called an expense. In this text, the terms "cost" and "expense" are used interchangeably. - Revenue. An increase in the value of the firm resulting from the sales of goods and services. - Income. The excess of revenues over costs for a specified period. The term is often used with modifiers to indicate specific quantities on an income statement (e.g., pretax income; net income). - Activity. A measure of production work. Traditionally, physical production volume (tons of ore or units of product) has been used as the measure of activity. Other measures include direct labor hours, equipment operating hours, and quantity of materials or supplies consumed. - Responsibility center. A segment of an organization that is responsible for a specified set of activities. In mining, individual operating divisions can be treated as responsibility centers, known as profit or cost centers. Departments within a division are generally treated as cost centers. - Cost center. A portion of an organization having responsibility for achieving specified levels of cost. - Profit center. A portion of an organization having responsibility for achieving specified levels of profit (revenues and costs).

Jan 1, 1999

By Dougal R. McCreath

The storage of energy in one form or another is a well established practice, demonstrated by the familiar sight of large oil storage steel tanks. Today, however, the problems of energy storage are taking on a new complexion. Increased emphasis on large and sometimes untried forms of energy storage is being generated by: (1) The uncertainties we face concerning future oil and gas supplies. (2) The growing need for the storage of peak-shaving energy on large utility systems. (3) The growing volume of highly toxic and energy generating wastes resulting from nuclear power plants. Concurrent with the growth of these pressures, legitimate environmental concerns now demand that the methods of storage which are utilized meet adequate criteria of safety and preservation of surface land, as well as fulfilling technical and economic functions. From these elements, increasing awareness has grown of the potential role that can be played by underground space in providing a storage medium for energy related materials. The vessels which must be built for underground energy storage will be built by the tunnel engineer, and the design requirements of such vessels will go far beyond the classical tunneling requirement to drive a stable, reasonably dry tunnel between two points. Depending on the nature of the material to be stored, the manner in which the storage is to be operated, and the specific risks to the environment which are involved, rock chambers must be designed as special purpose storage vessels. The tunnel engineer may be required to demonstrate that unusual pressure and temperature conditions can be sustained by the rock, or that containment of a toxic material can be assured. In certain cases there will be emphasis on

Jan 1, 1976

By R. E. Blair

The mining and minerals industry has been, and continues to be, at the cutting edge of high technology. Iron and steel built the Industrial Revolution/copper electrified the world/coal tars and petroleum and gas feedstocks developed the organic chemical industry. Industrial minerals now carry forward this tradition. Two, of hundreds of examples of hi-tech industrial minerals are quartz crystal and rare earths. Both demonstrate the international market aspects of mining, processing and finished product trade.

Jan 1, 1988

By W. A. Hustrulid

Introduction A problem that has faced mining engineers and mining geologists for many years is how to best explore a particular prospect so that the basic decision as to whether the material present is ore or only high-grade rock can be made with some confidence. It is obvious that one could not begin a large scale mining program on the basis of tests made on a few hand samples. On the other hand, one could not be 100 percent certain as to the average grade or tonnage before beginning development, as this would require the orebody to be mined out in the sampling process. The basic objectives of the exploration program can be stated as (1) to reduce mining risk; (2) to lessen the cost of development; and (3) to increase the profits of mining. The exploration program should be terminated when these objectives are no longer being met. The construction of tunnels is a specific mining operation. In the exploration program one should gather the data needed to determine (1) the type of excavation technique(s) to be used; and (2) the rate of advance that might be expected. As in the evaluation of an orebody, with the data collected it should be possible to estimate mining costs and project life. Unfortunately, at the present time, it is not possible to do this at least when dealing with medium to hard rock types. The reason for this, it is felt, is basically the inability to identify what specific rock mass properties are of use in tunnel design and to specify how these may be obtained in an exploration program. In short, the exploration program should be designed to give information regarding both the volume (length) and 'grade' (in

Jan 1, 1997