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By D. D. Lauriski

The Mining Division of Utah Power and Light Company is located in the coal fields of southeastern Utah -main office in Huntington, Utah. The Division will produce 6.5 million tons of low sulfur steam coal in 1988, making UP&L the largest underground mining operation west of the Mississippi. Coal is mined from three underground mines utilizing continuous miner and longwall mining methods. All coal produced by the Mining Division is utilized at UP&L's two largest steam-electric power plants, the Hunter and Huntington plants with a combined capability of 1,995,000 Kw. At UP&L we believe that to achieve success a company must have clearly defined goals which are understood, communicated and shared at each level of operation. We have also found from experience that a safe operation is generally an efficient and productive operation. As a Division, we have established a goal to achieve the safest, most efficient operation in the country. This is an ambitious goal. To achieve such a goal requires real commitment and a safety/training program capable of achieving needed results. The following is an overview of the program we have established at UP&L which has enabled us to reduce our accident frequency rate from over 40 in 1980 to 8.00 at present, as illustrated in Figure 1.

Jan 1, 1989

By Chris C. Sundberg, Ronald E. Heuer, Stanley L. Paul, Peter M. Douglass

Use of prestressed concrete cylinder pipe (PCCP) for pressure tunnel liners is gaining popularity with contractors, engineers, and owners. This paper presents loading considerations and a beam-spring computer model approach to tunnel liner analysis, together with ultimate strength (US) and service load (SL) procedures for liner design. The US procedure is best suited to check for adequate liner strength under extreme loading conditions. The SL procedure, based on conventional pipeline design practice, is considered more appropriate when addressing crack control and serviceability under normal working load conditions. Other design and construction considerations are discussed and a design example is presented.

Jan 1, 1987

By S. Mathur

Oxide particles are commonly used as fillers in plastics, paper, rubber, etc. (particulate composites). The successful fabrication of such composites is dependent upon the adhesive strength of the filler particles to the matrix. The compatibility of the matrix and the filler particles is generally enhanced by the adsorption of surface modifiers such as surfactants and polymers at the particle-matrix interface. To develop a scientific basis for the selection of the appropriate modifiers it is necessary to understand their adsorption mechanisms. specifically, the adsorption of polymeric additives is attributed to a combination of chemical and electrostatic interactions, hydrogen bonding and van der Waals forces. Hydrogen bonding has been suggested to be the primary adsorption mechanism for nonionic polymers. However, a literature survey of the Poly(ethylene oxide) (PEO)-oxide system suggested that PEO, a nonionic polymer, was substrate specific. A systematic study was undertaken to investigate the adsorption mechanisms of PEO on oxide particles. It was determined that strong Bronsted acid sites on the surface interact with the ether oxygen, a Lewis base, of PEO to induce adsorption. In this work, characterization of PEO binding sites on oxides is reported and the mechanisms of PEO adsorption are discussed.

Jan 1, 1999

By William A. Ribich, Hans A. Hug

INTRODUCTION Providing sufficient thrust, particularly in the proper manner, is one of the major problems of conventional hardrock drilling and tunneling machines. For instance, with tunnel boring machines, massive jacks, mechanisms, and structures are required to generate and transmit the forces to the cutting head. One pays for this massiveness both in terms of material (dollars per pound) and in the attendant difficulties of transporting and maneuvering such machinery. The effect of an efficient thrust generation method on system size is evident when one considers conventional shaft drilling equipment. Raise borers are small enough to be used underground, while conventional big hole drilling equipment requires large amounts of space, personnel, and support. Proper application of the force is another problem, even with smaller holes such as blastholes. While one can load most tricone blasthole bits to their limit with such drill rigs as the Bucyrus Erie 61R or the Gardner Denver 120D, transmitting very large forces through the relatively flexible mast and drill pipe leads to large vibrations, fatiguing of the mast structure, and impact loads on the bit. In the following, a new method of generating the required rock fragmentation force is presented. Furthermore, the force is generated and applied in such a fashion that not only can the equipment size and weight be reduced, but also the cutter and equipment life can be increased.

Jan 1, 1974

By J. K. Phiri

Copper mining is the main activity in Zambia and is confined to the large scale operations, mainly on the Copperbelt. The Copperbelt covers an area of size l00km by 50 km with a total of 10 underground and 5 open-pit mines operated by Zambia Consolidated Copper Mines (ZCCM) Limited. Most of the operations in these mines involves drilling and blasting. The loading of broken materials is by both manual and mechanical operations. Among the many risk factors associated with mining on the Copperbelt, is the occurrence of Pneumoconiosis which in the recent past has become quite prevalent and thus an important occupational health hazard for the industry. This study was carried out with the aim of establishing trends of pneumoconiosis incidence through the annual data collected by Pneumoconiosis Medical and Research Bureau of the Ministry of Health in Zambia, so that a basis could be formed for future research work. The study covers over 1,000 certified cases of Pneumoconiosis between 1960 and 1990

Jan 1, 1993

By W. Robert Power

Stone is considered by many to be the premium material for beauty and durability in all kinds of construction. Its use dates to the dawn of civilization and only buildings made of stone have survived from ancient times. The use of stone relative to other materials declined from the beginning of the present century reaching a low point in the third quarter, but there has been a resurgence in the use of stone in construction during the past decade, due probably, to new techniques for producing stone, a greater recognition of its beauty and durability, and greater affluence among consumers. The aesthetic appeal of stone is attested to by the many attempts to simulate it in synthetic materials. Today, natural stone is considered by many to be the ultimate in aesthetic appeal, durability, and ease of maintenance. Consumption of dimension stone has increased dramatically during the past decade. The US Bureau of Mines reported that the total value of US consumption in 1978 was $1 13 million and that total imports were valued at $65 million in 1979 (Anon., 1980). In 1989 consumption of domestic dimension stone was valued at $208.3 million and imports at $525 million. This dramatic increase occurred after demand had decreased at an average rate of 2.5% in the two decades prior to 1978 (Anon., 1980). More than half of the imports come from Italy, but production of dimension stone has increased worldwide spectacularly. Meaningful statistics on dimension stone are hard to acquire. The finished piece of stone is a highly value-added product, but stone may be sold as rough blocks, sawed slabs, or finished product. The same piece of stone may therefore be sold and reported three or more times. Furthermore, although the quantity of stone is most commonly reported in tons, stone cladding is more often sold by the surface area and at the same price for different thicknesses. By any measure, however, the production and consumption of dimension stone has increased dramatically during the past decade. A significant indication of the resurgence of stone was the introduction of two new trade publications during the 1980s. Stone World (Tradelink Publishing Co., Inc., Oradell, NJ), introduced in 1984 is published monthly and Dimensional Stone (Dimensional Stone Institute, Inc., Woodland Hills, CA), introduced in 1985 is published monthly. Both magazines provide useful information on new technology, market trends, producing areas and companies, and other information not previously available.

Jan 1, 1994

By W. Ter-Minassian

Besides the question of the stability of the roof and walls, one of the main problems encountered with tunnelling and shaft-sinking through the soft ground of alluvial origin forming the sub-grade of most large towns is settlement. Public transport and road tunnels in town centres are particularly affected, as they cannot generally be designed at any great depth for several reasons, such as the fact that ventilation shafts and access to the surface by means of stairs, escalators, lifts, ramps and so on must be fitted into the limited space available and are therefore costly, and because of the difficulties of driving below the water table. It is for this reason, coupled with the need for wide radius curves, that tunnels now so often pass close under buildings and monuments which must not be exposed to any risk of damage from subsidence during excavation. Grouting is the usual method used for consolidating soils, improving their strength and making them less compressible, but it is itself liable to cause heaving and cracks in the buildings above and has many other attendant dangers, including continually revised estimates which are the reason for the often inordinately high costs met with in urban tunnelling to-day. The mechanics of the problem have been studied and it has been found that a fraction of the total settlement is

Jan 1, 1997

By K. C. Jordi

Many systems which are modelled mathematically result in a model where the relationships between some or all of the parameters are found to be non-linear. These systems are usually complicated further by a desire to make the system achieve multiple and often conflicting objectives or goals simultaneously. Rozwadowski (1970) developed a model to describe the total discounted net profit of a mine as a function of the amount of ore developed and of the grade of the amount of ore mined. Dynamic programming was used to determine the policy which gave the maximum net present value. In this paper it is shown that the relationships between the variables can be approximated by piecewise linear functions. This is amenable to solution by an algorithm based on the simplex algorithm of linear programming. The goals of maximizing the net present value, the total net profit and the total gold output are incorporated simultaneously into a goal programming formulation of the system. The resulting model is characterized by a large number of disconnected constraints. These are decomposed into several smaller problems and the problem solved. The solution is examined to discover the sensitivity of the system to changes in certain parameters. In particular the interaction between the three goals is analysed to determine whether there is conflict between any of the goals and, if so, what the trade-offs between the conflicting goals are.

Jan 1, 1979

By R. J. Rice, K. F. Denning

Effect of iron on the removal of arsenic, mercury and selenium from gold mining effluents. Arsenic, mercury and selenium are common trace elements in gold tailing effluents that require removal before the water is either recycled or returned to a receiving body. One of the better methods of removal of these elements is the use of iron salts whereby, the metal is trapped on the freshly precipitated hydrolyzed iron oxides either by adsorption or enmeshment of the fine particulate and hence, removed from solution. The metal removal is effected by iron to metal ratio, pH, temperature etc. Pilot plant tests have shown that mercury can be reduced to < 5 ppb Hg, while full scale tests on arsenic and selenium have achieved levels of < 50 ppb As and < 10 ppb Se in well controlled systems.

Jan 1, 1993

By B. Jensen, B. K. Abraham, G. J. Tuck, A. D. S. Gillies

A dust concentration meter has been developed with Australian coal industry support for the measurement of total airborne dust concentrations capable of causing explosions in underground coal mines. The instrument, The University of Queensland Dust Meter (UQDM), measures the effective dielectric constant of a mixture of coal dust and air that is drawn between the plates of a capacitor, the capacitance of which is measured by a ratio-transformer bridge and synchronous detector system. This technique measures small changes in capacitance to approximately 1 part in 106. The unique design of the capacitor sensor permits a precise volume of coal dust and air mixture to be sampled. This arrangement overcomes difficulties inherent in optical dust measurement. The meter is portable, battery powered, incorporates data logging and has intrinsic safety approval. The operation of the meter is discussed. The system is designed to monitor dust concentrations along a coal mining face and provide concentration profiles leading to the development of suppression strategies. If data from underground tests are available, the meter&apos;s potential to contribute to establishing safe working conditions underground will be discussed. Other areas of potential application of the measurement technique are also examined.

Jan 1, 1993

By Ali Soltani, Scott Santti

The Gold Quarry Mine is a large scale open pit mine located 11.3 km (7 miles) north of Carlin, Nevada. The operation consists of an open pit mine, two milling facilities, a leach crushing plant, and three dump leach pads. Gold Quarry is operated by Newmont Gold Company, which is 90.1% owned by Newmont Mining Corporation, a Denver based company. The property is the largest of the three gold producing properties operated by Newmont Gold Company on the famous Carlin Trend. This paper will give a general overview of the Gold Quarry mining facilities and detail mine operating practices. Specifics on cost saving ideas being implemented and those under investigation will be discussed.

Jan 1, 1989

By W. F. Kane

Underground geologic mapping is an extremely important aspect of any on- going ground control plan. However, the actual use of data derived from such a program is difficult and often leads to subjective analysis. In this regard, computer software has been developed that utilizes a statistical determination of unstable ground conditions based on geomechanical and operational data and collected by mine personnel on a mine-wide, or regional basis. Categorical variables, such as faulting or joint frequency, are selected from local experience to form the framework of a representative data base. Statistical comparisons between the selected variables and a particular ground control problem are conducted and correlations subsequently made. The probability of encountering unstable conditions in virgin areas is assessed as information from these regions is gathered. This data can be derived from surface mapping, cores, and/or geophysical logs. As mining progresses, new data is merged with the existing data base to form a more comprehensive and extensive unit. The advantages of this approach and the acquisition and maintainence of a large data base include the more accurate representation of existing mining conditions, increased confidence in analyzing future problem areas, and elimination of the difficulties which arise when using ground control theories derived for other, often very different, locales.

Jan 1, 1986

By William J. Taylor

Strictly defined, a stull is an inclined or horizontal timber support; a vertically placed timber is defined as a prop. Common usage allows the catchall term "stull" to refer to all such uniaxial mine support, regardless of orientation. Typically a stull is a round wooden column that is wedged in place to provide short-term auxiliary support between sill and back, or between hanging wall and footwall. Stulls may be used exclusively or in con- junction with other support systems such as roof bolts, shotcrete, or cribbing. Stulls are used both as local temporary support in stoping operations and for uniform systematic support installations. Where stoping areas are to be abandoned soon after excavation, stulls may be used to provide temporary support during mining operations. Where controlled caving and subsidence is required, stull supports are designed to fail in a systematic, predictable manner. Wood type is selected on the basis of availability, price, and load carrying characteristics. Coniferous woods are typically used, especially to carry heavy ground loads. Brittle woods are generally avoided because of their tendency to fail suddenly. Gradual yielding failure is preferable to sudden, unexpected failure of the support. Some usage of wood from deciduous trees such as cottonwood and other poplars has been reported in Grants, NM. These stulls reportedly mushroomed as the ground load increased but continued to maintain their structural integrity. Stulls fabricated from structural steel are used in special applications. Adjustable lengths are commercially available in mechanical, hydraulic, and pneumatic designs. The high cost of mechanical stulls limits their use to mining systems where recovery and reuse is possible. End blocking, also called headboards or footboards, uses wood blocks that are placed between the stull end and the ground they are supporting. The blocks are typically 50.8 to 101.6 mm (2 to 4 in.) thick, 203.2 to 304.8 mm (8 to 12 in.) wide, and 381 to 609.6 mm (15 to 24 in.) long. End blocking serves to distribute the support over wider back area. Compression of the end blocking gives visual indication of wall movement prior to failure of the stull. A common application of the stull is in flat-bedded uranium mining during pillar extraction. Many western US uranium mines use a pillar pattern development to delineate the irregular ore pods. After development of an appropriate sized pillar, the ore pillars are then sequentially mined out, leaving the undercut hanging wall or back to cave. Where thickness of the ore is less than 4.3 m (14 ft), stulls are generally used to provide ground control as the pillar is removed in slices. Experience dictates the density of stull placement. In general, the number and size of stulls should be sufficient to resist ground closure and to provide support for drilling and loading operations adjacent to the pillar. Stulls next to the mining face are often lagged 0.9 to 1.2 m (3 or 4 ft) up from the floor (or sill) to confine the blasted ore to a passage next to the pillar. Mucking is simplified by this confinement. Experience dictates whether back control along a mining face requires removal of stulls to allow con- trolled subsidence of the back or hanging wall. Without caving or closure, abutment pressure can create poor ground conditions near the pillar.

Jan 1, 1982

By Victor F. Hollister

This report summarizes data available on the Fort Knox gold deposit to the end of 1989. It is presented courtesy of Fairbanks Gold, operator of the Fort Knox mine. The ore body and the data base are being expanded in 1990, but this summary is pertinent for inclusion in a case history volume that, in part, stresses porphyry-type deposits. Fort Knox is a pluton-hosted gold deposit 22.5 km (14 miles) northeast of Fairbanks, AK. It is easily accessible from Fairbanks, and ultimately it will be the largest open pit gold mine in Alaska. The Fort Knox pluton has an interesting historical record, and it has been discovered at least twice. Fig. 1 shows the geology and location of major plutons in the Fairbanks mining district.

Jan 1, 1991

By Patzen Wu

The Hai-Shan No. 1 Coal Mine, located in northern Taiwan, is one of the typical coal mines on the island which, limited by natural condition, are mostly small in scale. With the advancing longwall method, the mine is now winning a seam, 80 cm thick, at a 32° dip, with a working depth of 824 m below surface. The annual output is about 50,000 mt of clean coal. At the working gallery, the virgin rock temperature may go up to 46°C, difficult to be brought dam to n acceptable level: because .of the tropical climate with high intake temperature and high humidity. Besides, at this depth, the intake air that goes down the long inclined shaft generates considerable heat due to autocompression. The mine is ventilated by a set of axial-flow fan with 38 m3/S of intake air at 2.2 KPA WG. With this volume of air, the temperature at the working-face is usually above 30°C WB. Appreciable lowering of the temperature is not expected even with an increased volume of ventilated air. For this reason, decision has. been made to try the installation of a pilot underground refrigeration unit near. the lowest gate road to cool the intake. air. from 32°C WB to 28°C WB which seems acceptable to on-the-spot workers exerting heavy physical labor. The experimental unit is designed for carrying away a total heat load of 90 Kw. The capacity of the unit is 200 Kw. The unit consists of a compressor, an evaporator, a condensor and a motor. The heat rejection is done in a cooling tower. Chilled water is circulated from the evaporator to the cooler by insulated pipes. The cooler consists of 90 Kw-coils with two fans and forces air by flexible ducting onto the working face. This paper examines mainly the effect of this additional reduction of working temperature, on working efficiency of the workers. Another aspect of this experiment is to evaluate the overall economy of underground refrigeration in small-sized coal mines under tropical condition. The success of such an experiment may lead to wider application of refrigeration to render many of the deeper mines economically workable.

Jan 1, 1980

By L. Henry Smith, David C. Arthur

The Williams Mine is Canada&apos;s largest gold producer, with annual production of 14,000 Kg (450,000 ounces) from 2,300,000 tonnes of ore. Highly mechanized and automated underground mining practices are employed in order to achieve and maintain high levels of productivity and minimize costs. The Mine Ventilation System is modified to include a new Vent Raise and Variable Pitch Vane-Axial Fan. This addition allows several fan installations underground to be decommissioned. A substantial net savings in installed horse power is achieved. Heating costs associated with underground ventilation air are a significant portion of mine operating costs. Air heating costs are substantially reduced by recovering heat from upcast exhaust air, mine water and compressor cooling circuits. This waste heat is used to supplement propane fired air heating systems for underground ventilation air. An additional benefit is the availability of a heat sink for summer cooling of the compressors. System design, energy savings data and payback calculations are presented.

Jan 1, 1997

By R. S. Mateer

Linear programming on desktop computers is commonly used to optimize coal blending proportions. The objective function is usually the cost of the blend. The constraints consist of materials and heat balances as expressed as linear functions of the blend. This is illustrated in Example 1. Inclusion of a sulfur compliance constraint is more complex because the maximum permitted sulfur percentage is not a pre-specified constant. Rather, it is a function of the calorific power of the blend itself. The current limit of 1.2 pounds of sulfur dioxide per million Btu may be expressed as: Sulfur Max % = 0.6 • H/10,000 with H in Btu/lb.

Jan 1, 1994

By J. A. King, D. R. Weir, P. C. Robinson

Preconcentration of Porgera ore results in high recoveries of gold into gravity and flotation concentrates. The bulk of the gold is contained in auriferous pyrite flotation concentrate and is not readily recoverable by direct cyanidation. Oxidation in autoclaves at high pressure and temperature produces a residue that contains the gold in recoverable form. Pilot plant treatment of the autoclave residue is described, through washing and jarosite decomposition stages, to cyanide leaching and recovery of gold and silver by carbon-in-pulp techniques. The concern associated with disposal of plant effluents are also addressed.

Jan 1, 1987

By M. K. Pathak, A. K. Mukhopadhyay, D. C. Panigrahi

Changes in machinery operating and design parameters often result in unexpected vibrations or changes in the vibration patterns. Vibration in a system is an undesirable element that can cause machinery distress. Potential damage can be prevented by identifying the vibration level that is due to the changed operational parameters. This is necessary for the safe and reliable operation of plant equipment. This paper presents a documented study on vibration events that resulted from alterations in operating and design parameters in a mine ventilation fan and analyzes the causes by defining the sequence of events that led to its performance deficiency. This paper is based on experimental effort to study the vibration behavior of a ventilation fan under varying operating conditions.

Jan 1, 1999

By Agne Rustan

INTRODUCTION This work is a continuation of the preparatory study by Rustan and Stöckel 1979 (3) and (4) of the possibilities to introduce automatic mine ventilation in Swedish mines and construction works. The preparatory study has been financed by the Swedish Board of Technical Development. In the study it was recommended that an automatic step by step control of the fans near the working place due to diesel exhaust emission would be the best solution. A more advanced alternative would be to regulate the fresh air continuously in proportion to the contamination. The latter alternative has been studied by Boliden Mineral Co in the Udden mine. In this study it was found that the air supply could be regulated continuously but it was very important where the sensors feeling the contamination were placed. An intense study of the environment underground is now being planned by our division together with specialists from the National Board of Health and Safety, The Swedish Work Environment Fund, LKAB and the local Governmental Inspection of the Workers Safety. Different gases, radon, dust, airspeed, moisture temperature and pressure is planned to be measured continuously and correlation between the parameters is going to be established to decide the best measurement parameters for regulating the system. The best situation of sensors is also going to be studied. Despite this work hasn&apos;t been done yet this paper covers some of the problems which could be encounted with continuous regulation. In this report the environment has been studied during the test with step by step regulation of fans by radio. Diesel vehicles are the largest polluters under ground in Swedish mines and we have therefore suggested that the large diesel vehicles should regulate the fans. The goal of this study has therefore been to find how active diesel vehicles should be able to start and stop gallery fans at both intake and return air. In this paper different methods for activating fans are discussed. Then the best methods are chosen and tested in the mine. In this study we have found that changes of temperature is a cheap and effective method to start and stop cross cut fans in sublevel caving and radio signals seem to be an attractive system for start and stop of gallery fans. This work has been done in close collaboration between LKAB in Kiruna and the University of Luleå - Division of Electronics and Division of Mining and Rock Excavation. A reference group for the project has been established with ventilation experts from the mines, representatives for the local mine worker&apos;s unions and authorities from the local Governmental Inspection of the Workers Safety. VENTILATION SYSTEM STUDIED In the project the ventilation system at LKAB in Kiruna has been studied. The mining method used is sublevel caving with 9-13 m slice height. The air is heated winter time over ground by hot water heat exchanger. The main fans are pushing air down to a main distribution level along the 4000 m long and about 100 m wide orebody. From the distribution level, air is taken through shafts down to the sublevels, where it is pushed through the levels by local gallery fans on both intake and return side, see fig 1. The air ( ~ 8 m3/s) is moving freely through the gallery head. The cross cuts are ventilated with smaller fans, diameter 500 mm, and flexible duct, see fig 2. The aim of this study has been to study how to start and stop gallery- and cross fans and examine the environment when the fans are stopped . In Sweden there are no regulations telling that a minimum of air amount must be supplied. Instead the hygienic limits must be fullfilled.

Jan 1, 1981