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By Jan K. Wolski

This paper addresses jet fans used as booster fans within mine ventilation networks. The static pressure developed by the jet fan was determined using the momentum theory. The influence of various parameters on this pressure was analyzed. A method was proposed for determination of the jet fan characteristic curve . The distance between the jet fan and a point where the fully developed static pressure can be measured was determined. It was shown that a reduction cone can significantly improve the jet fan performance. Verification experiments conducted in the Waldo mine are described.

Jan 1, 1995

By W. E. Horst

In Part I of this paper we describe two techniques that were employed in the development of mathematical descriptions of the size reduction process which takes place in a ball mill. In Part II we show how the comminution model was imbedded in a process model to effect steady-state and dynamic simulation of a closed-circuit grinding operation. Increasing emphasis is being placed on development of approaches whereby the essential characteristics of a process can be succinctly represented in terms of a mathematical description of the relationships that exist among important process variables. This activity, commonly known as mathematical modeling, predates modern electronic computers: however, these computers with their tremendous computational capability have given new impetus to the whole field. Although the computer is quite helpful in the development of mathematical models, the real value to the engineer lies in the fact that computers represent such a powerful tool for simulating systems described by mathematical models. As a consequence, engineers may simulate and thereby study the behavior of complex. interacting, systems over a broad range of process variables and configurations once appropriate process models have been developed for the sequence of steps comprising the process.

Jan 1, 1970

In 1936 a young Dutch geologist discovered an exposed ore mountain in the remote, mountainous province of Irian Jaya, Indonesia. This was the beginning of one of the most overwhelming challenges ever faced in obtaining mineral resources from the earth. The challenge was to traverse mangrove swamps and reach deep into the almost impenetrable jungles of the Jayawijaya Mountains which have an elevation of 4900 meters (16,000 ft.). The target was an almost inaccessible mountain of copper ore.

Jan 1, 1988

By C. D. Buttgereit

A variety of mathematical techniques are available in the pertinent literature concerning the interpretation and reduction of aeromagnetic data. The quantitative methods applicable to this data en¬compass a wide spectrum including filtering, continuation, derivatives, reduction to the poles, spectral analysis, and "undraping" of flight line data. With the aid of the digital computer, the techniques listed, and others, can be computationally performed on a gridded data set. In addition, current sophisticated computer hardware permits the systems analyst greater latitude in the storage and retrieval of data and in the display of resultant naps on a digital x-y plotter than previously available. Although many interpretive techniques concerning magnetic data have been published and computer machinery has been on the market, little has been written incorporating both disciplines into a unified digital processing system. In the present paper, a general purpose system in given which in designed for routine use in the interpretation of aeromagnetic (and other potential field, etc.) maps.

Jan 1, 1970

By Patzen Wu

Taiwan is located in the orogenic belt of island arcs on the western rim of the Pacific Ocean. The structure of the Taiwan coal fields is much complicated as a result of active Cenozoic orogenic disturbance in Plio-Pleistocene time. The abundant faults and folds have created poor structural conditions of the coal seams and some peculiar safety problems in mining however, the domestic coal still played an important role in the economic development of Taiwan for the years before 1968. Because of increasing mining depth and a decreasing number of miners, the coal production dropped from nearly 5.1 million metric tons in 1968 to 2.45 million metric tons in 1981. There were 173 small active coal mines and about 22 thousand miners in 1981. The coal mining in Taiwan has a history of more than one century. Specific efforts have been undertaken in solving major coal mine safety problems such as gas outbursts, bad roofs and weak floors, difficulty in ventilation due to deep underground mining, spontaneous combustion etc. We have thus acquired much helpful experience which, we deem, is worth reporting at this meaningful meeting.

Jan 1, 1982

By W. E. Bardelmeier

The high speed conveyor type self unloading bulk carrier concept has been around for about 70 years. Although the design was developed, refined and steadily improved in the Great Lakes, to date limited numbers of such vessels have emerged in the bulk ocean trades, and these have tended to concentrate within specific mineral trades. For example, North American gypsum companies have embraced conveyor self unloaders to the point where such vessels almost exclusively carry the gypsum requirements of this part of the world. One major aluminum company has developed an impressive fleet capability in self unloaders. Application of other ships tends to be fragmented through several mineral trades. A few years ago a new phenomonen began to appear on the Great Lakes. Whereas it had historically been accepted in that region that self unloaders were effective vessels for the minor bulk trades including limestone, coal, salt, gravel and sand; they had seldom been employed heavily in the big volume iron ore trades. Suddenly, however, the new generation of 60,000 ton Lakers which emerged were all designed as high speed self unloaders. The new vessels intended to trade especially in ore, or alternatively especially in coal, have somewhat different internal features, but the important point is that all are self unloaders.

Jan 1, 1979

By R. A. Paul

WIDCO, operator of the Centralia Coal Hine, chose dredging, a method not commonly used for overburden removal, as the fastest, safest, and most economical method for mining through an alluvial filled valley. Now that the work has been completed, how did the cost and schedule compare with the original estimates? What would we do different next time in preparing for a dredging contractor? What are the potential pitfalls working with a dredging contractor? Would we do it again? When should dredging be considered as an overburden removal option?

Jan 1, 1989

By Ricardo Gomez, C. T. Ogryzlo, A. A. Dor

This paper reviews the historical background leading to the development of the project. It gives a description of the exploration program and resulting geological and ore reserve information together with plans for mining. A discussion is included of the three processes investigated for the project: 1. Rotary Hearth and Magnetic Concentration 2. Shaft Furnace and Electric Furnace 3. Rotary Kiln and Electric Furnace Results of pilot plant campaigns conducted at Fiskaa, Norway, and Riddle, Oregon, on the process chosen for the production of ferronickel are presented. The paper continues with a review of the considerations involved in selection of commercial plant equipment and concludes with comments on the current status of the project.

Jan 1, 1979

By V 9. 0 / 300 dpi

Papua New Guinea (PNG) stretches from the equator to Latitude 12° South and from Indonesia's Irian Jaya Province in the west to the Solomon Islands in the east (Figure 1). The population totals 3.5 million people who are mostly concentrated in highland valleys on the main island and around the coast. This paper outlines the history of mining, describes the natural, cultural and regulatory setting of mineral discoveries and highlights, by example, some of the more idiosyncratic environ-mental aspects of mining developments in PNG. It concludes with remarks on the progress made in the fifteen years since environmental matters entered the agenda for the establishment of a new mine in PNG.

Jan 1, 1988

By D. McBride

Representative samples are required from process streams in order to accurately measure chemical and physical characteristics. This information can then be used by process operators and metallurgists to evaluate the process and effect control actions for the operation. The capture and presentation of representative samples can be critical to measuring values, such as elemental analysis and particle size, with on-line or near-stream analyzers. A comprehensive multi-physics model has been developed and used to better understand the effects of slurry flow and particle segregation under certain operating parameters. An algebraic slip model coupled with a free surface algorithm is used to track motion and position of particles and phases within a specified geometry.

Jan 1, 2009

By M. Heger

February 2, 1999 marks a milestone in earth-moving technology at the San Miguel Lignite Mine. It was on that date that The North American Coal Corporation (NAC) took delivery of three Leica Dozer 2000 GPS grade control systems for use on its bulldozers. The primary reason for the purchase of these grade control systems was to prove that GPS technology could safely and economically be utilized on heavy equipment to assist operators in defining grades. If these properties were successfully demonstrated, the ultimate vision of the project was to expand the system to a point were GPS would become the primary means of providing grade control information to the mine’s heavy equipment operators. Twenty nine months and more than $500,000 later this vision was realized when the final bulldozer operating at the San Miguel Lignite Mine was equipped with Dozer 2000. Presently North American Coal has a total of nine Dozer 2000 GPS grade control systems at San Miguel providing cut and fill information to operators 24 hours a day. These grade control systems have allowed the San Miguel operation to increase safety, reduce costs, improve operator attitude, and better ensure environmental compliance. This article discusses both the nature of these benefits and some of the issues that had to be dealt with along the way.

Jan 1, 2002

By Chen Bingchen, Ma Shaojian

A new magnetic liner, with unique magnetic circuit and novel structure designs, was developed. It was characterized by light weight, low noise, as well as corrosive and abrasive resistance. The wear rate of the magnetic liner was one twentieth and one ninth those of the manganese-alloy steel and rubber ones respectively. The forming mechanism of the protective layer and that of influencing factors on magnetic liners were also investigated. The research results could not only instruct using magnetic liner, but also widen their application.

Jan 1, 1995

By B. T. Lusk, J. M. Hoffman, J. Silva Castro

Blast vibration induces sounds within neighboring residences. A housewide vibration and sound monitoring system was installed in a West Virginia home subjected to blasts from various distances and directions. Eighty-nine blast events were monitored and analyzed. Fifteen channels of data were collected, including data from three triaxial geophones, one airblast microphone, one uniaxial geophone mounted on the wall of the house (response channel) and four microphones that recorded CD-quality sound waves inside the house. Each of these channels was recorded on the same time scale. The response channel signal was easily separated into ground vibration and airblast-induced movement, due to differences in the time of arrival. This response channel was then compared to the sounds recorded to determine which component of blast vibration induced the maximum sound response. Blasts at distances less than 762 meters (2,500 feet) had maximum sound responses from both ground vibration and airblast, while for blasts beyond 762 meters (2,500 feet), the maximum sound response was caused by ground vibration without exception. When airblast was identified as the dominant sound generator, the peak amplitude of the sound was directly related to the amplitude of airblast. When ground vibration was identified as the dominant sound generator, the peak amplitude of sound was not related to the amplitude of ground vibration. Findings from frequency analysis showed that the frequency content of sounds inside the house was not related to the frequency content of airblast or ground vibration, regardless of source. This finding suggests that residents will have difficulty determining the source of blast-induced noise in their homes. The proposed airblast response factor (ABRF) can aid blasting operations to determine the dominant source of sounds inside a complainant’s house based on the time-of-arrival relationships. With this site-specific information, public relations responses can be developed accordingly.

Jan 1, 2010

By P. K. Songfack

The transport of slurry within the ball mill depends on the peripheral velocity and porosity of the ball charge. Residence time distribution and mill hold up are of-ten used as indicators of the mode of transport. In this work, the transport problem is tackled via direct simulation of the three dimensional motion of the ball charge. In doing so, the following quantities are calculated: (i) ball size distribution as a function of the distance from the feed end of the mill (ii) mean peripheral and longitudinal velocity and longitudinal velocity of balls of different sizes, and (iii) the spatial distribution of porosity within the ball charge. Hence, the problem of transport is handled as a motion of part of the slurry with the ball charge and part as hydrodynamic flow through the porous structure.

Jan 1, 1993

By J. C. Cawley

This National Institute for Occupational Safety and Health study was conducted to focus future research on the most significant electrical problems in the mining industry. Data from 1,926 mine electrical accidents (including 75 fatalities) that occurred between 1990 and 1999 were studied. Coal and metal-nonmetal operator- and contractor-reported data are presented. All data used in this analysis were MSHA closeout data, except 1999, which were preliminary data. Electricity was the 4th leading cause of death reported in mining despite being the 14th leading cause of injuries. Electrical shock, not electrical burns, caused 70 of the 75 electrical fatalities reported. About one-half of mine electrical accidents and fatalities occurred during electrical maintenance. Suggestions for mitigating electrical hazards are proposed.

Jan 1, 2002

By Brian H. Zelenko, Patricia M. Perry

INTRODUCTION The environmental requirements of the next section of Washington, D.C. METRO subway tunnels present unique challenges to the Contractor. The 14th Street Tunnels contract includes twin 975 m (3200 linear ft) soft ground tunnels. A stringent environmental soil and groundwater monitoring and free product recovery program was specified by the owner. A project-wide dewatering program hinges on satisfactory completion of the environmental requirements. Implementation of the Contractor's environmental program is discussed, including the pros and cons of the program, as they relate to progress of the project. Environmental issues on tunneling projects have become an important part of the urban tunnel construction process. Delays associated with environmental issues can have a major cost impact on tunneling projects. This paper will discuss the first of five Washington Metropolitan Area Transit Authority (WMATA) tunnel and station contracts awarded in 1994. These contracts are part of WMATA's Fast Track Plan to complete the original 166 km (103 mile) system by 2001. As such, stringent environmental requirements have been specified as a part of these contracts to limit delays associated with local regulators in order that the tunnels may be constructed on schedule.

Jan 1, 1995

By T. Wang

A new generated NaNO3 ? NaNO2 ? KNO3 ternary thermal energy storage system which has low melting point as 124°C and high specific heat capacity was studied for the short and long?term thermal stability by using the Thermogravimetric Analyzer (TGA). Based on the actual working condition of molten salt in solar two, the simulated cyclic thermal stability measurement was also conducted. The ternary system demonstrates excellent short ? term thermal stability and thermal reliability after cyclic heating and cooling processes. However, in the long ? term as well as the simulated cyclic stability measurement, large amount of weight loss was observed. Moreover, the stepwise long ? term isothermal study reveals that below 440°C the weight change is minimal and this temperature is viewed as the upper limit temperature of thermal stability for this ternary system. To determine the lost phases at high temperature above the upper thermal stability limit, techniques such as XRD and SEM are used to compare the condition of the salt mixture before and after the long ? term thermal stability study. On the basis of the comparison, it can be concluded that the major weight loss was due to the decomposition of sodium nitrite.

Jan 1, 2012

By S. Daniel Thompson

In underground coal mining, the specification and control of belt and bunker capacities are complicated by (1) stochastic and intermittent conveyor loading, (2) a limited ability to reduce surge at the mine face, and (3) occasional overlapping of loading from two or more mine faces on the conveyors. Recently, because of longwall mining and other factors, the capacity requirements of most mine conveying systems have risen substantially; as a result, efficient capacity design and control have become important mine planning issues. This paper reviews these design issues and their associated modeling procedures. Design considerations and modeling difficulties are also examined.

Jan 1, 1996

By P. Petropoulakis

Computer technology in the mining activities of our company has been applied in the last decade. In this presentation the experience gained by applying this computer technology in mining spescific applications are reported. Attention is given to the problems phased out and to the methodology used for software selection, centralized and decentralized development, data processing personnel and end users training and support. The paper concludes with a report of the first results obtained and a look at the future developments of the system.

Jan 1, 1989

By M. S. Bickers

Prior to 1970, the environmental liabilities associated with mine construction and management were few. Mostly, they were aimed at health and safety matters. At that time less than two dozen codes were incorporated into the engineering design and they were somewhat static and well known by the engineering designers and managers. These codes issued by governmental agencies and professional associations are listed in Table 1

Jan 1, 1988