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By H. E. Bonner

The recovery of fine coal has historically had limited success due to the intimate clay association on the surfaces of the coal particles. This clay presence has detrimentally affected conventional beneficiation techniques resulting in a recovered product containing unacceptably high concentrations of ash and moisture. An ultrasonically activated tray that operates in a continuous fashion has been developed that separates the clay film from each particle's surfaces. This separation is of sufficient duration to allow conventional beneficiation techniques to be utilized more efficiently.

Jan 1, 1989

By LeRoy Kienitz

There may be someone here who is not required to run his equipment at its maximum capacity. There may be some fortunate enough to have more crushers than needed, wider conveyor belts than required, and other mill equipment equally oversize. If so, then this paper will have no interest for him; but if most of you are in the situation we in the aggregate producing industry are in, then you probably wish to crowd your mill equipment to its limit. When you do this you must watch for block-up and overloads of all sorts. You need more eyes than you have to guard the critical points. The human eyes that now do nothing much, but watch should be freed for more productive work.

Jan 1, 1961

By W. A. Lawruk, L. J. Wilson, D. E. Stief

The Tower mill is a vertical stirred mill using steel balls or pebble grinding media. This device is designed for fine grinding at significant power savings when compared to conventional tumbling mills. This paper describes the machine and its operation, application, and performance for wet grinding.

Jan 1, 1988

By V. W. Skema, M. W. Smith

Pennsylvania has 4,000 km (2,500 miles) of streams that do not meet water-quality standards due to acid mine drainage (AMD), making AMD the greatest cause of water pollution in the state. The problem is mainly caused by abandoned coal mines. To abate AMD, Pennsylvania is using a watershed-based approach that includes remining as a key component of a comprehensive restoration strategy. The Tangascootack Creek Water-shed was targeted for AMD restoration through remining. Geologic mapping and overburden data were analyzed using Earth Vision software to identify areas of coal reserves that could be remined to improve water quality. Incentives are offered to encourage mining in these designated areas.

Jan 1, 2002

By Alban J. Lynch, Khairun Azizi

Education and research have always followed production in the mineral industry. Almost all of the leading mineral education and research units in the world today are in developed countries which had strong mining industries created during the 19th and 20th centuries to meet the demands for minerals due to the Indus- trial Revolution. It is in those countries where the main advances in mining and metallurgical technologies have occurred. But it is in the developing countries, often with traditions which have not favoured engineering initiatives, that the mineral industry is growing. Legislative changes and high exploration expenditures in many of those countries are of such a nature that many mineral discoveries will be made and mines and plants built in them during the next decades. Developments must be accompanied by increased activities in education, research and technology transfer in mining and processing, particularly those which are computer based. Malaysia is a developing country with the objective of achieving developed status by 2020. It has a short history of tertiary education and industrial research and a growing mineral industry. It is now building the education and research programs which will give strong support to its mineral industry. The progress which is being made in the computer based components of these pro- grams, and the factors which influence them, are discussed.

Jan 1, 1996

By W. P. Stroud, R. S. Dennen

A ground penetrating synthetic pulse radar system has been used by the US Bureau of Mines to probe into a coal pillar to locate hidden structures or anomalies. Direct matrix inversion was used to obtain a velocity image of the interior of the pillar. The reconstructed image showed the existence and location of a relatively low velocity material within the pillar. Core samples were taken from the pillar in a region surrounding the low velocity material. Analysis of the cores showed the presence of a clay vein coinciding with the low velocity material imaged in the tomogram.

Jan 1, 1992

By Terry L. Logan, Arfon H. Jones, James C. Seccombe

Deeply buried coal seams [greater than 3000 ft (914 m)] are difficult and sometimes hazardous to test and complete due to coal sloughing, formation pressure anomalies and coal fine generation. Data collected while stimulating two deep coalbed methane wells located at the Gas Research Institute/Resource Enter¬prises, Inc. "Deep Coal Sean Project" test site in the Piceance Basin, Colorado, is presented in this paper. A single thick coal seam was completed openhole in each well. Core data, reservoir data, in-situ stress measurements, and pre-stimulation calibration test data were collected at the site to use in the design of the fracture stimulation treatments for both wells. A nitrogen foam fracture fluid treatment was selected for the first well and a linear gelled water for the second well. Treatment pressures were monitored with a downhole quartz pressure transducer. Atypically high treating pressures were observed, possibly indicating coal fines plugging at the fracture tip or increase in fluid viscosity caused by interaction of the generated coal fines with the fracturefl uid. In addition, a comprehensive fracture diagnostic effort was employed during the fracturing of the second well; namely, triaxial borehole seismic, seismic televiewer, hydraulic impedance monitoring, gamma ray log (in conjunction with radioactive additives in the sand), and temperature log. The results indicate a vertical fracture was created parallel to the face cleat as expected.

Jan 1, 1986

By Kal V. S. Sastry

Mathematical and expert system models are being used extensively for mineral process engineering; nevertheless, standardized methodologies for their computer implementation do not exist. In meeting this need, this paper introduces the concept of a process software model, or more specifically an object-oriented software model, and presents a detailed methodology for its development involving software model specification and development. These software models provide a formal basis for the subsequent design and construction of software objects corresponding to the real world process objects.

Jan 1, 1995

By S. Ouyang

The four most important parameters controlling the flow of as in coal are the gas content, permeability, diffusion coefficient and clear characteristics. Estimates of these and, more importantly, a good knowledge about the variations in their values over time are important for proper simulation of long-term gas production. This paper describes experimental techniques for the estimation of diffusion-coefficient and permeability values, along with their time dependency under simulated in situ conditions. It is shown that the permeability and diffusion-coefficient values are not constant, as they are usually assumed to be. There is a significant variation in their values, probably as a result of changes in the microstructures of coal associated with release and flow of gas. Finally, a technique to estimate clear parameter is presented.

Jan 1, 1997

By Charles U. Keranen

The Tilden Mine is an iron ore mining, processing and pelletizing facility located on the Marquette Iron Range in Michigan's Upper Peninsula. It has a designed capacity to produce 8 million long tons of pellets annually from 21 million long tons of crude. It is a partnership owned by The Cleveland-Cliffs Iron Company, Algoma Steel Corporation, LTV Steel Corporation, the Steel Company of Canada, Wheeling Pitts- burgh Steel Corporation and the Sharon Steel Corporation. Cleveland- Cliffs manages and operates the Tilden. The crude ore averages 35% iron and is primarily non-magnetic iron oxide and silica. The major ore mineral is martite. Hematite, earthy hematite, goethite and magnetite are also present. The principal gangue mineral is chert. The ore grains are mostly in the 10 to 25 micron size range which necessitates very fine grinding for liberation. The concentrating process is the most complex one used in the iron ore industry. The unique technology for Tilden was developed in the mid and late 60's. The design and construction occurred in the early 70's and operation of the first phase which was of 4 MLTPY capacity began in October. 1974. Expansion of the facility to the current 8 MLTPY capacity was completed in 1979. Chemicals are the key to the beneficiation process at the Tilden Mine. The flowsheet utilizes selective flocculation - desliming, cationic silica flotation and concentrate dewatering by thickening and filtering. Nine different process chemcals are used. The control of the reagent feed systems is highly auto- mated. The entire concentrator is operated from a central control room. The concentrator flow diagram is presented in figure 1. The plant consists of 12 primary autogenous grinding lines, a common crushing circuit to handle an intermediate product within the primary grinding section, 24 pebble mill lines with cyclones and deslime thickeners, 12 flotation lines, 4 concentrate thickeners and slurry tanks, 8 lines of filters with six machines per line, and 2 tailings thickeners. A pumping system was installed in 1980 to permit the direct return of tailings thickener overflow water back to the reuse water pumphouse.

Jan 1, 1986

By I. Stavrakas

This work studies the variations of the electric current caused by the application of an electric field on marble samples when they are subjected to continuously increasing mechanical stress at a constant rate up to fracture. The external electric field is applied in a direction perpendicular to the applied mechanical stress. An increase of the level of the electric current was observed when micro-damages started to occur in the samples. The increase of the electric current was approximately 14%. Consequently, the current started to decay abruptly and the sample failed. This electric current recording is compared with the corresponding electric recording without applying the external electric field (Pressure Stimulated Current technique). Both recordings show similar qualitative characteristics. The most obvious of these characteristics are that the electric current starts to develop when microcrack structures start to form due to the externally applied stress. Both recordings show a maximum in the vicinity of fracture.

Jan 1, 2008

By A. R. Bath

During the late 1970s, pilot mining tests carried out on manganese nodules in the Pacific Ocean and metalliferous mud in the Red Sea demonstrated the technical feasibility of deep sea mining operations. However, the production of manganese nodules on a commercial scale is subject to numerous technical problems. As a result, a German-French joint development project has been underway since 1985. This venture focused on three key points: nodule pick-up device, locomotion of self-propelled collectors and hydraulic lifting of nodules. This paper presents the scope of this research and development program, its main results to date and future prospects.

Jan 1, 1992

By K. Mulukhov

Introduction The depth of open-pit mines continues to increase. The typical designed depth for large quarries is now in the 300 to 600 m (1,000 to 2,000 ft) range, with some quarries even reaching depths of 700 to 800 m (2,300 to 2,600 ft). The cost of handling material from such deep mines can be 60% to 70% of the total cost. The capacity of using a cyclic means of transport, such as trucks or skip hoists, continues to drop as the depth of the mine increases. In addition to the problem of maintaining relatively low slope angles for haul roads, increases in environment pollution and increased fuel consumption make the use of trucks ineffective below 100 to 150 m (300 to 500 ft). In handling large quantities of bulky materials, i.e., more than 15 to 20 Mt/a (16 to 22 million stpy), under fixed terminal points, belt conveyors are preferable in almost in all cases. An exception is when the lump size of the load is too high for the conveyor to handle. Belt conveyors in mines can handle loads having a maximum lump size of no more than 250 to 300 mm (10 to 12 in.). The use of a movable crusher prior to the belt conveyor in an open-pit mine would make the process very expensive. Such an operation could not compete with truck haulage on a cost basis. Belt-car conveyor The main factor that restricts the lump size for conventional belt conveyors is collision impacts between the load-carrying belt and idlers. These impacts are completely eliminated in the belt-car conveyor, which was previously described by Mulukhov (1977). The unique feature of the conveyor is that the load-carrying belt is supported by moving cars. Each car consists of a troughed cross strap that supports the belt with the load and two rollers, on which the cars move along upper and lower rails. Cars are connected by two endless chains revolving over sprockets. The system uses conventional drive pulleys, tail pulleys and return idlers. There are no fasteners between the carrying belt and the car cross straps. The conveyor belt simply drives the cars along by the force of friction between the belt and the straps. A belt-car conveyor was first installed in 1970 at the Karatau mining operation in Kazakhstan. The system was an elevating conveyor with an inclination of 20° and was located on the final part of the truck haul road. The conveyor transferred blasting phosphate ore from the quarry to the crushing plant. A bunker was mounted between the trucks and the conveyor. The maximum lump size was typically 1,200 mm (48 in.). However, there were some lumps as large as 1,500mm (60 in.), which was greater than even the belt width (Fig. 1). Because the prototype belt-car conveyor was intended only for industrial trails, it had a relatively short length of about 50 m (160 ft). Nevertheless, the conveyor yielded a substantial profit over the cost of truck haulage. Naturally, the first question one might ask is why such a system is not now widely used. The reason was the further development of a huge transporting complex for the whole quarry at the base of the belt-car conveyor. After successful industrial trials from 1971 through 1973, which demonstrated the systems engineering feasibility, the State Planning Committee of the USSR included the development of the belt-car conveyor in its plan for the development of the national economy. However, mistakes were made. First, a single organization was not in charge of the development. Second, a plant that was not specialized in belt conveyors was put in charge of the design and manufacturing of the conveyor system. In addition, the crusher was installed before the stacker, which negated the major advantages of the belt-car conveyor. For loading the conveyor, a special blade feeder with pendulum suspension was developed, but it was found unreliable. The main conclusion was that, in-

Jan 1, 2003

By N. R. Billette

In 1982 and 1983, a study was undertaken to analyse the applicability of Elbrond?s analytical model to suit the needs of Lake Asbestos of Quebec in their computerized open pit planning and scheduling strategy. The immediate goal was the assessment of the optimal allocation of trucks and the determination of the extra cost of in-pit blending. Data from 45 tonne trucks was used to estimate the mine capacity based on a fixed assignment policy. The tonnage yielded by the analytical model was compared with the results of a simulation program. Another point that the study high- lighted was the definition of efficiency parameters for the haulage system: shovels-trucks-crusher. The efficiency, both of the utilization of financial resources and of the operations, for the overall system reaches optimal values in very precise conditions for the number of pieces of equipment in operation. Such a parameter is proposed as a standard for the definition of an optimal number of trucks and shovels in operation. Deviations from this optimum do occur in a well-planned system for qualitative goals. These can then be quantified in terms of costs to the mining company.

Jan 1, 1986

By Jerome F. Machamer

Ninety percent of manganese is used as an alloying element in steel. Smaller amounts are used in dry-cell batteries, in aluminum and bronze alloys, and many other uses. The element has several oxidation states, and oxidation-reduction reactions control its chemical behavior. Manganese, in primary minerals such as rhodochrosite, rhodonite, and braunite, is in a divalent oxidation state, and manganese in secondary minerals, such as pyrolusite and cryptomelane, is in a quadrivalent state. Virtually all manganese ore production comes from three types of sedimentary manganese deposits. First, lenticular beds of manganese carbonate or carbonate-silicate rock in Early Precambrian volcano-sedimentary complexes in South America and Africa have been major sources of manganese ore. Second, laterally extensive beds of mangano-silicate and manganiferous carbonate minerals in certain banded iron formations are major sources of commercial ore and constitute the largest resource of manganese. Finally, manganese accumulations deposited in marginal to epicontinental basins are the largest source of current manganese ore production. Residual deposits resulting from the destructive weathering of rocks with a low manganese content have been, but are no longer, important sources of manganese ore. Most deposits have been altered to some extent by super- gene oxidative processes, and are economic because of that alteration. Outcrops of manganese ores are invariably oxidized and can be very deceiving as to the character of the underlying material. Nearshore facies of epicontinental basins, and nearshore age-equivalents of metalliferous black shales are among the targets for new manganese exploration. Very high-grade manganese occurs in sedimentary deposits altered by metamorphic and metasomatic processes.

Jan 1, 2001

By P. Tsang, S. S. Peng

The stability of longwall chain pillars depends not only on the mechanical properties of the coal and surrounding rocks but also on geological and mining conditions. To evaluate the effects of each variable, orthogonal experimental design was employed in a significance analysis. The study concluded that the stability of longwall chain pillars is mainly controlled by the ratio of pillar stress to pillar strength, the ratio of the Young's moduli of roof to coal and floor to coal, entry width, pillar width and the internal friction angle of coal. Additionally, horizontal stress, panel width and mining height also play a significant role.

Jan 1, 1996

By D. C. Panigrahi

The paper presents the development of a thermodynamic based network analysis model. It uses transient heat flow algorithm for computing the heat flow from strata and predicts the environmental condition in different branches of the network. Along with the environmental condition, the mass flow distribution in network is computed by using nodal pressure method based on linear theory approach. The algorithm has been coded using object oriented programming approach and it has been validated in actual field condition. The correlation is satisfactory.

Jan 1, 1997

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 J. S. Stachulak

Installation of a computerized mine monitoring and control system in two planned construction phases began in 1983. Phase one consisted of providing a central monitoring station located on surface for monitoring underground CO detection in Frood Mine's heated area. The implementation of this project annualized labour savings of $200,000. The cost of installation of an early fire warning system was $100,000. There are several CO sensor monitoring carbon monoxide trends through mine heated areas. To obtain an early warning, it is not good enough to know that a fire has started, but it is also necessary to know where the fire is located.

Jan 1, 1989

By P. Somasundaran, Bruno Lartiges

Two different groups of mechanisms have been considered in the past to explain the effects of chemical additives on grinding. While one group of explanations is based upon alterations of surface and mechanical properties of the individual particles, the other group depends mainly on the arrangement of particles and their flow in suspensions. In this paper some of the past work on grinding aids is reviewed and attrition grinding of a commercially important ceramic material, zirconia (stabilized with yttria) with polyaaylic acid as grinding aid, is studied in order to determine the effect of the aid on the ground product itself. It was observed that even though polyaaylic acid did cause a drastic decrease in the viscosity of the pulp, it did not have any major effect on the grinding of zirconia at least up to 2000 ppm and only minor detrimental effect above it. Importantly, complexation by the polymer was found to cause extraction of yttrium into solution with possibly significant changes in the surface chemical composition of the product.

Jan 1, 1992