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By Carlton H. Baab

In June, 1981 the Electric Power Research Institute (EPRI) issued a report titled "Control Systems in Coal Preparation Plants" to determine the status of instrumentation and automation systems in the coal preparation industry. EPRI concluded that the control systems presently being employed in the U.S. coal preparation plants "are relatively primitive compared with those in other mineral processing industries; and analytical instrumentation is virtually non-existent". Until recently, clean coal has had a low selling price and satisfying the purchasers' specifications required only minimum cleaning. However, it is becoming more apparent that the increases in coalfired utility power plants forced outage rates are relative to the deterioration in the quality of fired coal. Utility companies are becoming aware of the economic value of reducing the variability of ash, moisture and sulfur in steam coal purchase orders. New contracts are currently being negotiated between electric utilities and coal producers that include provisions for increased penalties if the product does not meet specifications. With tighter specifications on the quality of steam coal, interest is increasing in more sophisticated control systems. One type of device that is currently assisting the preparation plant operator optimize and control the coal cleaning process is nuclear based instrumentation. Nuclear instrumentation includes methods for measuring weight, level, and density as well as for performing elemental analysis on coal. This paper discusses the various types and applications of nuclear instrumentation currently in use in the coal preparation industry.

Jan 1, 1983

"When boring a tunnel, homogeneous hard rock is the exception rather than the rule. While contractors can set goals such as meters per month and performance incentives, it is also prudent to plan for difficult ground. A properly designed tunnel boring machine (TBM) can tackle fault zones, water inflows, squeezing ground, or whatever the risk may be. The alternative is not a good one: modifying the machine in the tunnel after bad ground is encountered. Not only does this result in increased downtime, but it also needlessly exposes the crew to the tunnel conditions. In the worst case scenario, the entire operation grinds to a halt.However, an accurate GBR cannot always be obtained, particularly for mountainous, high cover tunnels in remote locations. And even with a thorough GBR, unforeseen geological events can occur. What can be done in these situations? Difficult Ground Solutions (DGS) is ground investigation system with a suite of options that can be added to a shielded hard rock machine or dual-mode, Crossover machine to better enable advance when conditions are unknown or difficult conditions are anticipated.DGS consists of a set of integrated features tailored to a specific project’s geology. The main components of the system allow for ground investigation ahead of the TBM, increased monitoring and methods to keep a machine shield from becoming stuck.In fault zones and squeezing groundIf fault zones or squeezing ground are known or suspected, or if there is even a possibility of encountering them, this can greatly affect the TBM operation. Shielded machines protect the crew from the surrounding rock, and they can bore and line a tunnel efficiently, but in fault zones and converging material their shields can be their downfall. Avoiding a stuck machine is paramount to project success. DGS employs several features to avoid the problem of a machine becoming stuck. The first of these is multi-speed cutterhead drives. These drives effectively give the machine multiple modes of operation—high speed, low torque for hard rock, and low speed, high torque for difficult ground. Designing a machine with high-torque, continuous boring capabilities allows that machine’s cutterhead to restart with break-out torque in difficult ground. The net effect is that the machine can keep boring in the event of a face collapse and can bore through fault zones and running ground where the potential for cutterhead jamming exists. Going one step further, multi-speed gearboxes give the machine the ideal earth pressure balance- (EPB-) type torque if larger sections of soft ground are anticipated.Secondly, TBMs can get through squeezing ground and faults using Continuous Shield Advance. This design utilizes a stepped shield configuration — where each successive shield is slightly smaller in diameter — to avoid becoming stuck in converging ground. External shield lubrication is an added insurance against becoming stuck, using a series of radial ports that can pump Bentonite into the annular space to act as a lubricant in squeezing material.As a last effort, if a machine has already become stuck the TBM can utilize augmented, or “super” thrust. Additional thrust jacks can be added to supply an extra boost in a short stroke, generating enough force to break loose a trapped shield."

Jan 12, 2017

By Jerrold J. Marcus

United states reserves of oil and gas have been steadily declining while consumption of petroleum products has continued to increase. The nut result has been an ever increasing shortfall between supply and demand. This imbalance has been made up by imports of both oil and gas causing a strain on the United States Balance of Payments. To complicate the situation further, exporting nations have recently formed a cartel and dramatically increased the selling price of petroleum products. To meet U.S. energy demand, increased attention has been drawn to the production of synthetic oil and gas from coal. To date, considerable research has been conducted and is continuing on various processes for liquefaction and gasification of coal. Some of these processes are now in the pilot plant stage and at least one demonstration plant has been proposed. The coal conversion complexes envisioned will be very large, requiring substantial capital investments and abundant reserves of coal. Coal production to feed these proposed complexes has been estimated on the order of 75,000 tons per day. With the viability of these projects becoming economically attractive, the Office of Coal Research initiated a contract with Fluor Utah to determine and define the problems of surface mining coal at very high mining rates, under varied physical, geographic, and climatic conditions. The flow of recent events in the Middle East has created a greater sense of urgency for this study.

Jan 1, 1975

By Wallace W. Wilson

It scarcely 1s possible to read a new issue of any of the principal mining trade journals without noting some mention of a major new overseas mining venture with which one or more domestic companies are involved. These projects seem to follow a fairly consistant pattern; most are large open pit mines, with relatively low grade ore bodies but huge reserves; the total price tag will be in nine significant figures and around half or more of the total cost will be for infrastructure. West1 noted that nearly $7 billion is being invested annually for new mining projects and the expansion of existing mining ventures, in the free world. He anticipates that by the year 1975 such investments would reach the $10-11 billion annual figure, and that in the five year period 1972-76 total capital requirements can be expected to aggregate around $45 billion. The proportion of this total investment which will be financed in some manner is difficult to estimate because of the variety of available financing arrangements. West estimated that around 75% of the total capital would come from internally generated funds, with the balance from external sources. Conceivably a substantially higher percentage could be attributable to external financing, especially it the trend of recent mineral development in Canada and Australia is any criterion, and of course, including local sales of equity as a part of the package.

Jan 1, 1973

By Maria S. Adusumilli, A. Bhaskara Rao

ABSTRACT The presence of gold in lateritic crusts over mafic and ultramafic volcanogenic complexes in / and greenstohe belts, has called the attention in several parts of Brazil and also in Australia. Recent studies reveal the variety of structures and mineralogy of such crusts, and their importance in correlation with host(bed) rock types, as exploration guides, specially for greenstone belt metallogeny. The expected nature of growth of plates and/or nuggets in such crusts is under detailed study, and is considered as possibly due to dissolution and reprecipitation phenomenae of disseminated-fine-low grade ore in the host rock, in this investigation, laterite geochemistry, though incipiently discussed todate, is of fundamental importance and significance. Lateritic gold can be classified texturally as: dusty and diffused, fine, thin platy, taDular, and nuggets. Such gold is pure, and is often restricted to nodular (pisoliths, ooliths, concretions) forms or the matrix, that constitute the crusts or lateritised gravel beds which have an essentially goetnitic nature. Further this gold is recovered directly by mining the crusts or the adjoining placers with the metal derived from them. The thickness and extension of laterite crust zones is extremely variable depending oh the paleoclimatic conditions, and is conditioned to the favourable lithology and its structural expression. However, the "growth" of gold in these laterites will be conductive , without doubt, to several small scale mining activities, specially in the developing countries and regions limited to latitudes 309N and 309S.

Jan 1, 1987

By E Marambio, R Brändle, G Fischer, G von Rickenbach, M Fuentealba, L Burgos, R Luis Fonseca

In underground excavations, under high stress conditions, ground support systems must provide safe and effective response to dynamic events. These systems must be capable to resist dynamic impacts and yielding during the loading process. In this context dynamic testing of the reinforcement and retaining elements that compose the ground support system are required to study and improve the behaviour of these elements under dynamic load events. During the last years, Geobrugg has been working on the improvement of retaining products by testing them in a large-scale impact test facility located at Walenstadt, Switzerland. The test facility is composed of a double level platform with a square-shaped pyramidal trunk geometry, in the upper level housing a loading mass that drop from a height up to 5m. The loading mass is guided by one central steel pipe, and the impact occurs in the sample to be tested located at the lower level in a slab with an area of 3.6m × 3.6m where the ground support system is installed. During the last years, this innovative facility has been used to test several configurations of ground support systems. The results of these tests have enabled to improve the understating of the behaviour of ground support systems under dynamic loads. In this manuscript, the back analysis through numerical methods (central difference and Newmark’s method) of a ground support system tested with a double dynamic impact in 2019 is presented.

Apr 26, 2022

By E. (Walt) van Walsum

The MPTM was first applied in the U.S.A. in 1950 as described by Lewis, W.E., 1951. The method was then abandoned in the USA and rediscovered some 20 years later in France where it was greatly improved and widened in its scope of application. It was subsequently successfully introduced to Italy and Spain. The technique, at its present stage of development, provides solutions to tunneling in soil and in the softer rock types, which often were troublesome geological environments for tunneling. When used in conjunction with drilling-and-blasting, over break, excessive vibration, noise and fissuring of the rock can all be avoided. When used as an alternative to the New Austrian Tunneling Method (NATM), the MPTM provides safe, full face tunneling in stead of multiple headings, excavated sequentially; in addition, surface settlement can be virtually eliminated. When used as an alternative to a TBM, the method's flexibility and low capital cost make it attractive. This attractiveness is enhanced when ground conditions are erratic or when the length of tunnel to be excavated is limited. The method holds promise for tunnels of large cross section, to be excavated in soft ground or rock with unconfined compressive strengths of less than 80 MPa (11 600 psi). While in itself not new, recognition and development of the method's potential are. Further development work, aimed at increasing the range over which the MPTM can be applied, is in progress.

Jan 1, 1993

By John S. Anderson

The need for fuels and minerals in this country is estimated to double, triple, or even quadruple by the end of the present century. Even assuming more recycling of scrap metals and some priority allocation of energy, as has been done, for instance in war time, the projected increase in the nation's population and ever-increasing wants of that population will require vastly more minerals than are now being produced. Since mineral ores are being mined at lower grades, and since all minerals, including fuels, are having to be mined from deeper deposits, the amount of surface land to be disturbed will, inevitably, be increased. We cannot depend on foreign sources to supply all the extra requirements, since the non-U.S. population is increasing, in most cases, faster than our own. Furthermore, starting from a lower base, their mineral needs may accelerate more rapidly than ours. Restrictions on exports may be applied in foreign countries, if it appears that remaining reserves are not sufficient to fill the national needs. In vice; of the opposition which the mineral industry is receiving, as has been well described at these sessions and elsewhere, what can we, as mineral producers, anticipate as regards our ability to continue to operate, to sway nothing of expanding production? Although not minimizing the problems involved, it seems obvious that, except under emergency conditions, the country cannot tolerate a reduction in the available

Jan 1, 1971

By C. L. Sainsbury

For 10 years, the author has been engaged in a program of geologic mapping of the Seward Peninsula, Alaska, for the U.S. Geological Survey. Initially, two 1:63,360-scale quadrangles were napped by traditional methods of traverses by foot and by tracked vehicle, supplemented by reconnaissance from a light aircraft owned and piloted by the author. Five summers were required to map those two quadrangles, which lie north of the tree lice in typical Arctic climate. In 1967, the project was reoriented toward the reconnaissance capping of four 1:250,000-scale quadrangles, with helicopter support to be used for cart of each of four summers amounting to about 45 hours time per support year. The light aircraft was use-,' to support the field operations. Over the year,, the aircraft was used in progressively more geologic tasks, culminating in 1970 with a successful field test of rudimentary devices made to collect soil, rock, and sediment samples while the aircraft remained airborne. Additionally, an attempt was made j- 1970 to prepare reconnaissance geologic maps entirely by the use of the light aircraft combined with foot traverses [fr??], the landed aircraft. Several such maps, prepared at the rate of about one 1:63,360-scale quadrangle per day, were checked from a helicopter by an impartial observer end were found to be sufficiently accurate for reconnaissance mapping when reduced to 1:250.000 scale.

Jan 1, 1971

By George A. Takach

The U.S. Bureau of Mines is conducting research with the goal of automating underground coal mine roof bolters for greater mine safety. In the project described here, the Bureau has focused on automating the drilling portion of the drilling and bolting cycle. A drill monitoring system designed and developed by Parvus Corp. of Salt Lake City. UT, was placed on a Bureau model roof- bolting drill. The drilling parameters of torque, thrust, rotation rate, penetration rate, and position are monitored through sensors connected to an asynchronous, control-oriented local area network (LAN) that communicates with data-accumulating and data-processing nodes. By placing microprocessors at the two data nodes and at the valve control nodes, and combining these nodes with a personal computer (PC), the monitoring and control system can achieve parallel processing capabilities. Such capabilities are referred to as locally intelligent distributed processing. Only data that have changed significantly are reported through the LAN to a supervisory control and data acquisition (SCADA) system mounted on an IBM- compatible 80286 PC. The SCADA system displays the values of the drilling parameters and calculates the specific energy of drilling, which is then used as an indicator of the type of rock being drilled. Besides monitoring the drilling process, an operator at the computer can control the rotation and thrust of the drill from a remote location through the SCADA program and can set drilling parameters on the basis of observed values of the specific energy of drilling.

Jan 1, 1992

By Mike Horn, Keith Meade, Marvin L. Smallwood

Technological changes in programmable logic controllers (PLC)'s and the need to improve the architecture of Mine Wide Monitoring Systems (MWMS) has resulted in the design of a PLC based system at the Virginia Division of Island Creek Coal Company. The system which is presently in the installation phase, is a joint effort of Island Creek Coal Company, Westinghouse Electric Supply Company and Mining Controls Incorporated. The system uses an ethernet based network for graphic display of system data operating under the Genesis software package. Telemetry for the system utilizes the Seimens/Westinghouse L1 network operating over two twisted pairs. Remote telemetry uses fiber optic links and modems operating over standard telephone lines. 500 and 2000 series PLC's provide distributed data processing for the system with hierarchial processing operating under the Genesis software on the ethernet network for individual mine site monitoring along with the remotely located division office monitoring. System control and data acquisition is provided for underground MWMS operations and on the surface for a vast methane gathering system that is used for degasification of the mines and collection of pure methane for sale to the Columbia Gas Company as natural gas. The inability of industrial MWMS companies to keep up with the vast changes in technology, along with economic considerations associated with expanding the existing MWMS created the need for the development of the PLC based system to replace the older industrial monitoring systems.

Jan 1, 1993

By D. E. Munson, H. J. Sutherland

Empirical methods for describing the shape of the subsidence trough over coal mines in Europe are tested against field measurements of subsidence over longwall panels in the United States. The graphical methods developed by the National Coal Board in the United Kingdom do not correlate well with the U.S. measurements; however, the profile functions typically used on the Continent give quite acceptable fits to the data. In the case of two longwall panels mined at Old Ben No. 24 in Illinois, a trigonometric profile function appears the best choice; in the case of two longwall panels mined at York Canyon in New Mexico, an error integral function is somewhat superior. Analyses of subsidence development curves show that rate effects occur. A comparison of fitting parameters establish influence functions as an important methodology for future analysis. In conjunction with the evaluation of empirical methods, an analytic model based on material failure and bulking was developed. A key element of the model is the void-volume distribution function which establishes a mechanism for transfer of significant amounts of the mined volume to the surface. Preliminary calculations demonstrate the features of the model and illustrate close correlation to physical observations in the field. Moreover, centrifuge models simulating the subsidence process have been used successfully to demonstrate the dominant or key failure modes necessary to the analytic model. General features of the centrifuge simulations and model calculations correlate well.

Jan 1, 1982

By D. A. Karvonen

Although the economy in the Province of Saskatchewan has historically been agriculturally oriented, a major new source of wealth has been realized through natural resources such as petroleum and natural gas, coal and uranium and since the 1960's - potash. Potash or potassium chloride, in the form in which it is presently produced in Saskatchewan is used primarily as fertilizer, a source of potassium, one of three essential elements required for healthy plant growth with about 5 percent of production sold to the chemical industry for use in such products as soap and liquid detergent, glass and ceramics, textiles and some pharmaceuticals. Saskatchewan is estimated to have approximately 40 percent of known world potash reserves and its ten active mines account for some 25% of annual world production. The development of this resource was recognized to be important to the development of Saskathcewan. In an effort to guarantee a fair and lasting economic benefit to the Province of Saskatchewan the Potash Corporation of Saskatchewan (PCS) was created on February 4, 1975 through an Order-in-Council under the Crown Corporation's Act and later on April 1, 1976, the Potash Corporation Act provided for its continuation. PCS was given the mandate to acquire ownership of a significant portion of the potash mining capacity in Saskatchewan and to establish an organization capable of operating the facilities, marketing the product and conducting all of the other activities necessary for a successful corporation competing in the world potash industry.

Jan 1, 1983

By Siegmund Babendererde

1. Introduction In Sayreville, New Jersey, the Middlesex County Utilities Authority put the construction of a 1041 m long sewer outlet to tender in June 1989. It had an internal diameter of 3,36 m and was part of a sewage treatment works project for county Middlesex. The contract was awarded to the Lodigiani Company, USA, who employed Hochtief Incorporated as subcontractor to drive the sewer outfall. 2. Ground Conditions According to the preliminary geological site investigation, carried out by the consultants Metcalf & Eddy, the tunnel passed through marine deposits.

Jan 1, 1991

By Alfredo Romero Quispe, Carlos Hoffman Sampaio

This work presents a study of characterization of activated carbons for the adsorption of Au(CN)2- complex. A comparative study of six samples of activated carbons, three Brazilian and three produced out of Brazil was made in order to determine their qualification for a performance in adsorption circuits in the extractive metallurgy of gold. The adsorptive capacity and the kinetics of adsorption were compared to the physical and chemical properties of each one. The influence of poluant ions on the kinetics and loading capacity of aurocianyde anion was also determined.

Jan 1, 1995

Historian and storyteller, Duane Smith, will be the keynote speaker at the National Mining Hall of Fame's 10th anniversary induction banquet on Saturday, Sept. 6,1997 in the Museum Convention Center at Leadville, CO.Smith is a professor of history and southwest studies at Fort Lewis College in Durango, CO. He is also an award-winning author of 28 books about the West and mining. Hall of Fame Board Chairman Richard Moolick said the induction banquet event will mark the National Mining Hall of Fame and Museum's 10th anniversary in its Leadville facility, a century-old Victorian schoolhouse. Karl Elers, chairman of Battle Mountain Gold in Houston, TX, will be the master of ceremonies. He is a member of the National Mining Hall of Fame and Museum's board of directors. The six inductees into the National Mining Hall of Fame will be enshrined by Thomas Falkie, president of Berwind Natural Resources of Philadelphia, PA. He is also chairman of the Mining Hall's board of governors. The six inductees will join 132 mining greats who were previously honored. The black-tie (optional) banquet will be highlighted this year by guests who prefer to don 1890s dress for the occasion in the old silver-mining boomtown. A cocktail reception and open house will precede the banquet, with tours of the district and special events to follow on Sun- day, Sept. 7.

Jan 1, 1997

By Krishniah N. Murthy, James E. Monsees

BACKGROUND The development of public transportation in the Los Angeles Metropolitan area is, as in other cities, closely tied to the development of the area because of increases in population and commercial and industrial activity. Local transportation first appeared in the area in the 1870s when the population was fewer than 10,000 residents. Around 1910, after many consolidations of competitive interests, two large railway companies were formed: The Los Angeles Railway, which provided urban transportation in the Los Angeles City area, and the Pacific Electric Railway, which primarily provided suburban and interurban transportation. These two entities continued with their operations until after World War II, when the ownership passed on to the Los Angeles Transit Lines and the Metropolitan Coach Lines, respectively. By then the railroads needed new equipment, track rehabilitation, and, of course, more money-paying patrons. Lack of grade separation of railway facilities from other traffic increased commute times and encouraged travel by private automobiles. The romantic era of hopping on a Pacific Electric Company "Big Red Car" was coming to an end. As early as 1917, in fact, bus lines were substituted for unprofitable rail service. The Los Angeles Metropolitan Transit Authority (LMTA) was established in 1951 by the California Legislature to study and plan for improvements in the public transportation facilities in the Los Angeles area. In March of 1958 the Los Angeles Metropolitan Transit Authority took over the operation of the two lines.

Jan 1, 1989

By Sue W. Wells, James J. Moore, Stephen D. Lynch, R. Hunter White

This paper describes the products and services that Phelps Dodge Corporation desires from solvent extraction reagent suppliers and the partnering relationship that Phelps Dodge wishes to develop with these suppliers. Product topics include: 1) manufacturing concerns, 2) product and process quality control reporting and 3) reagent customizing to meet individual plant needs. Service subjects include distribution, delivery time, emergency re-supply, terms, and tailoring technical support. The partnering relationship discussion reviews mutual benefits, communications, reliability, cross-functional teams for problem solving and developing new opportunities, and long-term commitment.

Jan 1, 1994

By Neil Hepworth

Neves Corvo Mine employs four mining and four backfill methods, including paste fill. The paper shows how the strength requirement for backfill in primary stopes was calculated and the relationship between laboratory strength and in situ strength requirement. The liquefaction of paste in secondary stopes is discussed with methods to determine the liquefaction potential. It was found from laboratory tests and the preliminary results of the underground trial, that the liquefaction potential of the paste is low at 2% and is high at 0.5% cement. The results to date are inconclusive regarding 1% cement.

Jan 1, 2001

By D. M. Kjos

Large-diameter autogenous and semiautogenous grinding mills represent the primary thrust of the expanding grinding technology. In spite of initial difficulties, large autogenous and semiautogenous mills have reached an acceptable level of technology that provides the mineral engineer with a reliable, low cost means of ore comminution. A successful milling installation begins during the design stage of the grinding mill and the plant in which it is to be installed. This is particularly true in autogenous and semiautogenous mills. Critical mill and plant design factors should be considered while the mill and installation are still only "paper." Various current liner designs will be discussed ranging from lifter bar/plate to integral types. Modes of operation such as "high-low" will be considered. Liner maintenance procedures ranging from laydown area in plant design, proper mill shutdown methods, to installation and bolt tightening complete the equation to yield optimum performance possible for any particular grinding application. The objective of this paper is to discuss trends in wear materials, designs, and operating practices, and to provide some guidelines for good practice as we move through the 1980s. We will put together concepts that relate to the designs, materials, and applications so that higher performance can be obtained by the operator for his specific application. The concepts are shown as being in series became they are dependent on each other to achieve the desired performance: designs times materials times application results in higher performance (Arnson, Parks, and Kjos, 1983).

Jan 1, 1987