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By C. E. Capes

Reduction in the quality of resources and attendant increase in the quantities of fines to be processed present a major economic and environmental challenge for resource - based industries. It is becoming evident that agglomeration by immiscible liquid wetting will play a significant role in the treatment of these fines. Liquid phase agglomeration can be adapted to separate solids or liquids in highly divided form from liquid suspensions and emulsions. Diverse opportunities in coal fines recovery, novel fuels technologies and oily waste water treatment are cited here. The oil agglomeration of extreme fines from coal tailings, with consequent dramatic reduction in refuse for disposal, is now a commercial reality. It is suggested that this approach can serve as a prototype for the processing of extreme fines in an economical and environment ally sound manner.

Jan 1, 1989

By C. D. Harrison

The 1990 Clean Air Act Amendments specify national objectives for reducing sulfur dioxide emissions from coal-fired power plants System-wide reductions can be achieved by combining various emissions controls technologies and allowances, or compliance credits, that can be purchased, sold, or traded. As part of the Coal Quality Expert development project funded by U.S. Department of Energy and the Electric Power Research Institute (EPRI), Black & Veatch has developed an interactive computer tool, the Acid Rain Advisor (ARA). ARA allows the user to develop integrated system-wide compliance plans by comparing the costs and emissions reduction benefits for emissions allowances and various SO2 control technologies such as coal cleaning, fuel switching, and scrubber retrofits.

Jan 1, 1992

By J. A. Herbst, J. E. Bohrer, Y. C. Lo

A systematic approach has been developed to analyze a phosphate grinding circuit with a view toward determining promising alternatives for increasing mill capacity. This analysis was carried out and capacity increases were predicted in the context of detailed population balance models developed for the plant ball mills and classifier systems. Model development and verification was performed using data obtained in a series of batch tests and two plant test campaigns. The effects of feed rate, percent solids, ball size, and mill material filling, etc., on grinding were investigated in the laboratory and plant. Residence time distribution tests were also performed to determine the transport behavior in the mill. The population balance models were found to provide accurate predictions of full-scale grinding circuit performance. Based on the findings of this study, additional capacity in excess of 25% was predicted for these ball milling circuits by a proper combination of ball size change, mill dilution, and adopting screen classification in place of hydro-cyclones. These predictions have been confirmed by plant tests in which the recommended operating changes have been implemented. Understanding the effects of operating variables on breakage kinetics and the interplay between kinetics, transport, and classification has contributed significantly to increasing the mill capacity.

Jan 1, 1988

By J. A. Dlas Lima

Alunorte is a metallurgical-grade alumina refinery located in northern Brazil. This plant which was designed to produce 1.1 million mtpy of calcined alumina, started operation in July 1995. A process information system was installed before refinery start-up. It has been a main factor in process improvements, which resulted in an increase in production from 1.1 to 1.5 million mtpy. This system has been particularly useful for analyzing data and allowing retrieval of data by process engineers. This paper describes how a quality monitoring system to evaluate all aspects and stages of production, as well as alumina silo level and blending percentage, was developed. This system was designed to give support to ISO 9002 certification, which happened in December 1998. The quality monitoring system was developed using Microsoft Excel 7.0 and makes extensive use of VBA macro. The primary users of the system are shift foremen, managers and engineers, who use it to track the process and avoid variations in alumina quality.

Jan 1, 2000

By M. Argiantopoulou

In today?s mining environment, improving production, performance, productivity and profitability is crucial. Production, ancillary, plant and shipping equipment need to be monitored and controlled by online systems delivering production statistics and real-time information to everyone involved, including equipment operators. Traditional systems currently in use today, operate in an iterative mode constantly switching between scheduling and execution. However, the real world tends to change in ways that invalidate such advance schedules. Agent based computing has been hailed as the most significant breakthrough in software development and the new revolution in software. Agent systems are being used in an increasingly wide variety of applications, including complex mission critical systems such as Air Traffic Control. This paper presents the possible ways that multi-agent systems can be applied to mine production and rehabilitation scheduling problems with focus on real time fleet management, plant and equipment performance monitoring, downtime and delay reporting, stockpile management, personnel and equipment tracking and product distribution and transportation.

Jan 1, 2006

By George W. Luxbacher

The inclusion of a new term "planned subsidence" in the Surface Mining and Reclamation Act of 1977 has lead the U.S. coal mining industry into a new aspect of engineering: subsidence planning. Subsidence planning has necessitated the integration of geotechnical, civil, and mining engineering disciplines. Although much of the foundation and application work has been completed, subsidence planning is still a developing area. This paper discusses the application of subsidence planning in several brief case studies (a high voltage transmission tower, a sewage treatment plant, and a slurry impoundment), emphasizing the risk assessment aspects necessary to account for some of the uncertainties that may exist.

Jan 1, 1986

By Matthew Spedding

The complex nature of the carboniferous measures prevailing in the U.K. has dictated the types of mining required to exploit the coal seams. Most mines in Britain are referred to as deep mines in the sense that they operate at depths of 1800 - 3000 feet. The main system of coal transport to the surface is by vertical shafts which intersect the workable seams which at times number between 4 and 5. As mining has been practiced in most of the major coalfields in the U.K. for well over 100 years, with the initial extraction of the shallower and more profitable seams, the present management have been left a legacy of indiscriminate extraction which severely hampers their efforts to maximise the mine layouts. There is no single standard design of mining layout capable of meeting the wide variety of conditions which exist in the British coalfields. Mining layouts are subject to fixed and variable parameters. In discussing multi-seam working, the main parameter must be the effect of old workings above and below the seam to be extracted. There is a distinct lack of reliable information which would enable layouts to be designed to completely avoid or control these destructive forces. The guidelines are, therefore, mostly empirical.

Jan 1, 1977

By Felicia F. Peng

Two modes of collector addition techniques are applied in the column flotation for cleaning ultra fine coal. The collector can be: 1) added directly into the coal slurry through the feed system; and 2) gasified collector and transported in the gas phase through the bubbles. Operating parameters of the column flotation were investigated through three phases of work plans for Pittsburgh No.8 seam coal. In present study, the column flotation using two modes of collector addition techniques were tested and compared. Ninety percent or higher combustible recovery can be achieved by using both methods. However, utilizing the gasified collector addition technique in column flotation has more potential than direct liquid addition technique to obtain the higher recovery at same collector dosage.

Jan 1, 1993

By Ashis Bhattacherjee, Subrata Chatterjee, Michael T. Dewey, Christopher J. Bise

In order to continue the advancements made during the past two decades in the reduction of the severity of accidents and injuries in underground coal mining, closer attention will have to be paid to the increasing number of accidents resulting in disabling injuries and lost time. With the increased emphasis on safety training reflected in the Federal Mine Safety and Health Amendments Act of 1977 (Public Law 96-1641, and on MSHA's current focus on the application of Job Safety Analysis, it appears that the acquisition, evaluation, and application of accident and incident data will take on an even greater importance. To manage this large amount of information will require a significant commitment of time and attention on the part of mine training departments. A USBM-sponsored research project is currently being completed at Penn State which focuser on the development of a model training program for mining. The program is based on five distinct steps which represent the coupling of a needs assessment with the program implementation. The five steps are: 1) database analysis, 2) workplace observations, 3) identification of trainable problem areas, 4) a library of training resources, and 6) the implementation of the program. In each of these areas, the microcomputer has proven to be a valuable tool for collecting, analyzing, and presenting accident and incident information. This paper will detail the manner in which microcomputers have been fully integrated into the model training program. Examples of applications at existing mines will also be discussed.

Jan 1, 1992

By J. F. T. Agapito

Energy West Mining operates the Deer Creek and Cottonwood/Trail Mountain coal mines in the Wasatch Plateau about 40 km (25 miles) southwest of Price, UT. The Deer Creek Mine extracts the Upper Blind Canyon seam and the Cottonwood/Trail Mountain Mine extracts the Hiawatha seam 12 to 36 m (40 to 120 ft) below. Both seams average about 2.8 m (9 ft) in thickness. Cover depths exceed 550 m (1,800 ft) in a large portion of the unmined reserve. Stability problems at Deer Creek are mostly due to coal bursts caused by high stresses associated with deep cover and sandstone channels. Most of the bursts have occurred in gate pillars and, to a lesser extent, at the longwall face and during development. The introduction of a two-entry gateroad system with 9-m- (30-ft-) wide yield pillars has been a major factor in controlling and minimizing gate pillar [ ] bursts (Agapito et al., 1988). However, some bursting began to occur in the 9-m- (30-ft-) wide pillars as cover depths reached 550 to 610 m (1,800 to 2,000 ft). This was due to more rapid and higher abutment loading in areas with very strong roof and stiff floor.

Jan 1, 1997

By E. C. Grunsky

Spatial auto- and crosscorrelation assessment of variables can be carried out using quadratic function estimates. From the function estimates, multivariate relationships of the variables can be determined in the form of spatial factors. The calculation of the spatial factors requires computation of the corresponding amplitude vectors from the eigenvalue solution. This vector reflects the relative amplitudes by which the variables follow the spatial factors. Instability of some of the eigenvalue solutions requires that caution be used in interpreting the resulting factor pat- terns. A measure of the predictive power of the spatial factors can be determined from the auto- correlation coefficients and squared multiple correlation co-efficients which indicate which of the variables are significant in any given factor. The use of unconditional simulations provides a basis by which geological variables of varying spatial ranges can be modelled using the spatial factor technique. Simulations were generated for a variety of ranges and variables were created that form single or multiple combinations of the spatial patterns. The success of the spatial factor technique depends on the amount of associated noise, and the size of the neighbourhood relative to the spatial range of the variable. The predictive power of the components is dependent on these two factors. Problems with collinearity of variables can result in unrealistic eigenvalues and result in the failure of the method. Application of this method to spatial data in mineral exploration can assist in outlining spatially continuous zones of alteration associated with mineralization.

Jan 1, 1989

By F. C. Nicolli, J. P. Barbosa, P. S. M. Soares, A. V. Estevez

INTRODUCTION Spent household dry cell batteries are frequently disposed of with metropolitan wastestream (MSW) in landfills where they can leak due to handling or aging. Frequent rain and sun cycles, especially in tropical environments, coupled to the action of leachate, dissolve their metal constituents which will eventually reach rivers, lakes and underground water. It is well known that some of these metals are fundamental to sustain life and that is why living organisms concentrate them through their metabolism, but it has been also recognized that beyond specific limits they can definitely be deleterious to the environment. In other words, high concentration of heavy metals are proven to cause chronic or acute diseases and toxic reactions, by acting on mammals' kidneys, liver and nervous system. In addition, some metals frequently used in household batteries, as mercury and cadmium, are said to be carcinogenic (Landis et al. 1995, Silva et al. 1988). Occasionally, plants to treat MSW are coupled to compost production. Household batteries present in MSW can be dragged into these plants, contaminating their products and eventually reaching vegetables making them not proper to consume by people and animals. Alternatively, batteries are also conveyed to incinerators and burned, throwing into the atmosphere volatile species. These can either act as contaminants as toxic vapor species or be delivered by winds and scavenged by rains contaminating soils and water far away from their source. In conclusion, despite the treatment applied to MSW, one can say that battery residues are potentially environmentally hazardous. The careful assessment of the environmental impact caused by residues of household batteries it is not an easy task and it can be referred as a multivariable problem. First, many different household batteries are produced by industry and the potential environmental hazard associated to their disposal depends primarily on the type of battery and manufacturer's technology. These characteristics will dictate how resistant the battery case is to handling and the

Jan 1, 1998

By Stefan Gerl, Werner Stahl

Steam pressure filtration combines mechanical and thermal processes in one filtration device. Steam condensation at the cold layers of the filter cake, build a condensation front, which even removes the capillary water from the porous filter cake. Depending on the choice of parameters it is possible to achieve a very low residual moisture content. The influence of the parameters on the dewatering results was systematically examined on a bench-scale apparatus. This paper explains the physical fundamentals, the influence of the cake dewatering parameters, and one possible method of applying the process to a disk filter device as well.

Jan 1, 1995

By Patrick J. Ryan, Johann F. Kerl, Angelos N. Findikakis

Introduction Tailings disposal methods used by the mining industry include the use of on-land impoundments, surface and underground mine backfill and marine disposal. The latter method, where applicable and under certain circumstances, can be the most economical and best environmental option. The term marine disposal is used to describe deposition of tailings in the open ocean, coastal waters, fjords and inland lakes. A major element in planning and designing a marine outfall is the assessment of its potential environmental impacts. The nature of the disposed tailings, and the physical, chemical, and biological characteristics of the receiving water body must be carefully assessed prior to deciding whether marine disposal is an acceptable option for a particular project. During the last decade, the North American mining industry has demonstrated a commitment to studying potential adverse environmental impacts of marine tailings disposal and to continue monitoring of the receiving waters. Extensive monitoring programs have been undertaken by Canadian mines. Marine tailings disposal is not used in the United States today. One of the largest U.S. mines proposing to use this option is the Quartz Hill mine of U.S. Borax in Southeastern Alaska. To assure the regulatory agencies and the public of the viability and acceptability of this option, U.S. Borax undertook an extensive program of environmental studies aimed at assessing the impact of marine tailings disposal. This program was part of the feasibility and environmental permitting studies conducted by Bechtel Civil & Minerals, Inc, on behalf of U.S. Borax. Due to the unique nature of the proposed tailings disposal system, a Board of Consultants was established. The Board assisted in planning the modeling and field program and reviewed ongoing work. This paper outlines the basic elements of the marine tailings disposal study program which can be viewed as a prototype for similar studies elsewhere. Background The Quartz Hill molybdenum deposit is located on a knoll in an elevated valley in a mountainous region of southeast Alaska, about 45 miles east of Ketchikan (Figure 1).

Jan 1, 1986

By K. Soucek

Extraction of hard coal reserves, but also of mineral resources in general in the underground coal mines includes in itself many anthropogenic interventions in the earth crust. These interventions are closely associated with the solution of stability problems in the mine and with occupational safety. One of potential applications of such geo-technical interventions in rock mass is the chemical grouting technology. The chemical grouts are very suitable to affect the physical and chemical properties of rock mass. With the present development of chemical grouts, primarily based on polymers, there come into existence new composite materials during the grouting process (the so called geo-composites), which properties significantly differ from the original rock. An important factor, which affects a choice of chemical grouts and at the same time the effectiveness of grouting technology is the resulting properties of geo-composites. The properties of a coal geo-composite differ from the ones of the unmodified coal seam. On the basis of the laboratory geo-mechanical tests, the differences of properties of both material types were found. While the pure coal samples were destroyed very brittle and explosive, the geo-composite samples were making higher level of tenacity and load bearing ability after overstep of material strength. The presented paper discusses the different behaviour of these original and modified coal samples. The X-ray CT scans were used for observation and demonstration of failure evolution in these samples of pure coal and coal geo-composites after compressive loading.

Jan 1, 2006

By Dave Willis

In ME'S 1994 Powder River Basin (PRB) coal transportation article, the lead author described some destinations pursued by the railroads. As with many destinations, though, they turned out to be merely stops on the way to places that have yet to be reached. Along the way, the railroads discovered that making it better is a continuous process, not just something done in several phases. This was always known but not at the awareness level that exists in 1998 railroad environments. This update of the 1994 article includes railroad companies' plans for the future of rail transportation in the PRB.

Jan 1, 1998

By W. M. Hart, Q. H. Shen, J. S. Chen, S. S. Peng

The automatic data-acquisition systems that are now available can continuously monitor and record changes in leg pressure and changes in advancing ram stroke in every shield. These systems can record shearer position at any moment during a mining operation. The data obtained can be used to improve production and maintenance management and can be used to provide better roof control at the longwall face. Research now being conducted jointly by West Virginia University and Cyprus Amax Coal Co. is aimed at developing a longwall-management system (LMS) for mine operators. The LMS software package, which works in the Microsoft Windows NT environment, performs data interpretation and analysis, production management, maintenance management and ground-control management for longwall mining.

Jan 1, 1997

By Y. J. Wang

In the, mathematical analysis of electrical networks, the electrical devices are often modeled using idealized network elements such as current sources, voltage sources and resistors. An analogous approach is outlined for the modeling of mine ventilation networks, which can be considered nonlinear resistive networks. The proposed modeling technique uses the following five basic (nonreducible) elements: H, Q, D, R and N. These elements are characterized by their pressure gain or loss, their air quantity and their pressure-vs. -quantity relationships, each of which may be known or unknown. In addition to the definition of the basic elements, the necessary conditions for which there exists a unique solution are discussed This is performed using theoretical developments derived from electrical circuit theory and illustrated in example networks. The proposed procedures are useful in the solution and characterization of mine-ventilation networks.

Jan 1, 1997

By A. T. Iannacchione

Recent fatal injuries occurring during pillar retreat coal mining call for better identification of the hazards and recognition of risks. Ground control hazards associated with room-and-pillar retreat mining tend to intensify with depth, requiring extra precautions in the form of additional controls. In many locations these activities are further complicated by local complexities often associated with unique or novel circumstances, such as over-mining or under-mining. One technique recently studied by NIOSH, Major Hazard Risk Assessment (MHRA), may help mine operators to mitigate the risks associated with pillar recovery operations. The approach was trialed at two underground coal mines in southern West Virginia that are currently practicing pillar recovery. The first step in the MHRA process involved reviewing the segments or parts of the pillar extraction mining system and identifying associated hazards and threats to the operation. Some of the high risk hazards at these two sites included: ? Rock fall during pillar extraction covers equipment and injury occurs during recovery operations, ? Rock fall above the roof bolt horizon, potentially injuring ? workers and/or requiring recovery action, ? Rib fall under deep cover, potentially injuring workers, and; ? Strata instabilities associated with subsidence of the interburden due to simultaneously mining two seams in close vertical proximity to one another. The mines? risk assessment teams then considered each threat individually in order to systematically identify potential unwanted events. The top unwanted events were examined individually using structured risk analysis tools. The output from the process includes a list of priority existing controls for monitoring and auditing, and a second list of potential new controls. These controls consisted of: Examples of best practices, ? Enhanced communication, ? Implementing standard operating procedures (SOP), ? Protocols for emergency response actions, ? Effective layouts, ? Efficient monitoring, and; ? Successful audits. This paper documents the process as it unfolded at the two mines, and analyzes the strengths and weaknesses of the MHRA technique as it applies to pillar recovery operations. This work was part of a larger NIOSH research project. NIOSH was responsible for: 1) facilitating the risk assessment process known as Major Hazard Risk Assessment (MHRA), 2) documenting the risk assessment process, and 3) providing mine management with a written draft summary of the risk assessment process. The results of the risk assessment represent the thoughts and opinions of the individual risk assessment teams and should in no way be construed as an endorsement of the risk assessment output by NIOSH or the University of Pittsburgh.

Jan 1, 2009

By Jerry C. Tien

An overcast is a form of air bridge which permits one air current to pass another without mixing. It is an essential and indispensable ventilation device for underground air distribution in horizontal mineral deposits. Overcasts are also a major source of shock pressure loss under- ground. However, a well thought out overcast plan, and a well constructed overcast, will give minimum shock loss, which in turn can save money (Tien, 1986). So far, most research on shock losses has been concentrated on splits and junctions, and bends and turns, or on underground regulators. Practically nothing could be found in the literature regarding losses caused by overcasts (see reference on shock losses). In this investigation, shock losses are quantified for an overcast with different configurations, which will give useful clues toward an aerodynamically designed overcast.

Jan 1, 1987