Search Documents

By C. Caceres

Fibre reinforced shotcrete in combination with other types of support systems is becoming the leading support method for underground excavations, especially those present in low quality rock masses. Sudden or rapid ground support failure can expose workers to safety hazards, damage to equipment and others resulting in production interruptions that will impact the cost of operation. Knowing the peak and post-peak strength characteristics of the support system over time are of major importance. Round Determinate Panel Testing of fiber reinforce shotcrete is the primary test used by the mining industry to determine strength characteristics; however, the tests are costly and significant manpower is required in a mine environment to build, store, handle and test the panels. For these reasons numerical modeling can result in an effective method to produce realistic results. This paper examines the strength characteristics Round Determinate Panel tests and its ultimate application in underground excavations, using Itasca?s three dimensional particle flow code (PFC3D).

Jan 1, 2010

By F. Calizaya

This study summarizes the ventilation requirements for the highly mechanized PT. Freeport Indonesia's underground mine operation in Irian Jaya, Indonesia. The deep ore zone (DOZ) is a coppergold deposit that is being developed underneath the current intermediate ore zone (IOZ) mine. One of the company's current plans is to prepare this mine for a steady ore flow of 25 kt/d (27,500 stpd) by 2003. This study includes the estimation of airflow requirements for various mining activities, the design of major intakes and returns, the determination of airway resistances and specifications of fan duties. It also includes the results of air pressure/quantity measurements in existing airways and the standards stated by the current Indonesian mining law.

Jan 1, 2000

By John P. Cummings

Glass is the most unique substance which man has made. It is understood that Phoenician sailors playing on the beach in Mesopotanmia around 12000 BC, produced glass by the fusion of sand and soda in their campfire. Glass is unique for many reasons. However, let us consider the following. It is made of materials which are opaque and yet glass can be translucent, transparent, or opaque. It can be as soft as cotton or stronger than steel. It transmits light readily and yet is totally impervious to gases and liquids. It is chemically an inert, creates very little pollution in its manufacture. It is made of the most abundant raw materials on earth. It is readily recyclable and has little pollution in its disposal. Glass containers are made principally from sand (that is, silica), soda, which is sodium carbonate, and lime, which is calcium carbonate, plus decolorizers or colorants and cullet. The proportion of cullet, broken glass, in most glass tanks today is roughly 10 to 20% of the glass product. In most cases, the cullet used in the plant is glass from off-ware, or broken ware, which is a waste product within the plant. Cullet has the following advantages. It contains all of the raw materials normally used in a batch. It tends to melt at a lower temperature than batch, thus saving some fuel, and, finally, by forming a crust above the normal melting system, there is a tendency to cut down air pollution.

Jan 1, 1975

By Jr. Garnar

Heavy mineral mining has been a relatively small but important Florida industry for over sixty years. Geology of the Florida heavy mineral deposits is similar. Each formed along active coastlines after which the titanium minerals were upgraded in TiO2 by post depositional oxidation and leaching of the iron. There are four heavy mineral plants currently Operating in Florida. Ore is mined by dredges and the heavy minerals concentrated by gravity separation. The heavy mineral concentrates are further processed with high tension and electromagnetic separators to Produce titanium mineral concentrates for TiO2 pigment manufacturing plants. Zircon sand is produced as a co-product at all of the Florida plants. Staurolite is produced by Du Pont and Titanium Enterprises. Du Pont also markets a kyanite-sillimanite product. (Monazite is produced by Humphreys and Titanium Enterprises). Reclamation of mined-out land is an important part of heavy mineral mining. At the Du Pont plants soil is removed ahead of the dredge and placed over the quartz sand tailings. Grass is planted after fertilizing. A year later the land is fertilized again and pine trees planted. Most of the heavy mineral deposits now being mined will be nearly exhausted by the end of the century. New deposits to be mined in the 21st century will probably be smaller and lower grade than those now being mined. Advances in mineral processing technology will have to be made to allow these lower grade deposits to be mined economically.

Jan 1, 1978

By D. Lelinski

Air-sparged hydrocyclone (ASH) flotation is one of the new promising technologies. Numerous applications have been successfully tested since its conception; nevertheless, research and development efforts have continued to provide for further improvements with respect to operating conditions and design considerations. Results from experimental studies on bubbles generation in the ASH system are presented in this paper. Bubble size distributions generated during ASH operation have been determined using a high-speed photographic technique. The influence of many factors including surfactant concentration, water flowrate, and porous tube pore size has been studied. Test results indicate that these process variables have a profound effect on the bubble size distribution. With an increase in surfactant concentration or water flowrate (shear field) the bubble size distributions become narrower and shift toward smaller average bubble diameters. However, the influence of pore size is more complicated. Depending on the experimental conditions the average bubble size was found to range from about 100 to 300 microns in diameter.

Jan 1, 1995

By Nobuharu Isago, Atsushi Kusaka, Kosuke Kawata, Dohta Awaji

"The immediate ring closure method, in which the entire periphery of the excavation area is closed immediately with an initial support within a short distance from the excavation face, has been increasingly used in Japan, especially, as one of the most effective countermeasures against difficult ground conditions in conventional tunneling. For reasonable design of this method, the performance requirements for the initial support should be clearly stated. The analysis of construction data of 30 road tunnels and the three-dimensional numerical modeling based on real data suggest that the immediate ring closure stabilizes the tunnel structure and the ground around it because of the inner pressure effect of the initial support, especially, for low ground competence factor and small internal friction angle. Finally, the bending compressive strength and the cross-sectional geometry of the initial support have to be considered in the tunnel design while considering the earth pressure and ground properties. INTRODUCTION Conventional tunneling methods often deal with difficult ground conditions such as soft ground or squeezing ground conditions. The immediate ring closure method, in which the entire periphery of the excavation area is immediately supported within a short distance from the excavation face (Figure 1), has been increasingly used in Japan as one of the most effective countermeasures against difficult ground conditions in conventional tunneling (e.g. Takahashi et al., 2011; Nakaoka et al., 2013). The immediate ring closure method was empirically identified as effective for reducing ground surface subsidence and tunnel deformation. However, the working effects of the method have not been clarified sufficiently. To improve the design of this method, the working effects of this method and the performance requirements for the initial support need to be clarified. The relation between the effect of immediate ring closure and earth cover has been clarified (Mashimo et al., 2008; Awaji et al., 2013),"

Jan 1, 2016

By S. Amirshenava, S. Nadimi

"Premature and unplanned mine closure can result in significant adverse impacts on the environment and community and need to be managed appropriately. Risk management techniques can reduce the negative impacts and risks of early mine closure. Risk Assessment 3D Model, is an efficient tool to quantify risk. The aim of this paper is to identify the mine closure risks in Choghart iron ore mine, and calculate the overall mine closure risk level. The result shows that 51.4% of assessed risks have low risk level and the overall risk level of early mine closure is low. Keywords: mine closure, risk assessment 3D model, Choghart iron ore mine INTRODUCTION The modern mining life-cycle can be divided into three main stages; exploration, mining (opening and production) and post mining (mine closure, and reclamation). Mine closure is the critical component of the modern mining life-cycle and it refers to the period of time when the operational stage of a mine has permanently ceases (Heikkinen et al, 2008). Planned closure occurs due to the depletion of ore reserves, but sometimes it is premature. Laurance (2006) shows that only 25% of mine closure in the past 30 years was due to resource depletion and in 75% of the cases the mines were closed for the other reasons. Ghanbari et al (2010) demonstrated that 48.6 % of copper mine closure in the past 100 years was due to resource depletion and 51.4 % of copper mines have been closed due to other reasons. The main reasons of premature mine closure are as follow (Laurance, 2006; Ghanbari et al, 2010; Maiti, 2013): • Economic, (low commodity prices or high costs) • Geological, (over-estimation of grade and tonnage) • Geotechnical (adverse geotechnical conditions) • Technical (equipment failure) • Regulatory, due to safety or environmental breaches • Social or community pressures • Closure of downstream industry or markets • Flooding or inrush Minaei Mobtaker and Osanloo (2013) developed a mine closure prediction model based on the data collected from closed iron ore mines in the past 100 years. They showed that economic factors, exhaustion of ore reserve and geological conditions are the main reasons of iron ore mine closure. They treated mine closure as a decision making problem in order to predict the causes of mine closure, including the uncertainties of some mine plan parameter such as iron ore price, production and consumption."

Jan 1, 2016

By William A. Wallace

Common mineral resources (sand, gravel, crushed stone, etc.), which are so necessary for the construction of metropolitan areas, are rapidly being depleted or otherwise rendered unavailable in the very areas that need them most. However, the problem of planning for these resources involves a number of independent and dependent variables that must first be defined and related. Finally, a dollar value must be assigned where possible. Complex interrelationships between the variables and their dependence on outside factors has made mathematical "solution" of the problem of planning for non-renewable mineral resources difficult at the present time. Therefore, the use of computer simulation is suggested as a means by which this complex problem can be investigated. The purpose of this paper is to report on a continuing research program whose objectives are: (1) to delineate the factors involved in planning for the utilization of common mineral resources in urban-suburban environs; (2) to construct a planning model for these materials amenable to computer analysis, (3) evaluate the model by using test cases, and (4) perform a sensitivity analysis to determine the initial parameters in future planning for these materials.

Jan 1, 1968

By Joseph W. Mullan

The today status of air pollution control legislation and regulations can best be described as an exaggerated state of environmental limbo. The '70's began but one and one-half months ago yet it already has been very appropriately named "the decade of the environment." This certainly will be the decade for new legislation - new regulations and hopefully "Clean Air." Already Washington is faced with legislators playing "pollution politics" to the crowds. Students have redirected their efforts from Vietnam to the cleansing of the environment and everyone including the man on the street has become an environ¬mental expert. This is the decade we all face, but where are we today? Pollution is not a new problem. It has been with us for centuries and while much is left to be done, much has already been accomplished. I will try to make some comparisons of what I believe to be the good and bad points in the national air pollution control picture and hopefully will generate within each of you sufficient concern as to which comparisons are sound.

Jan 1, 1970

By Errol L. Montgomery

The region of metalic ore deposits in northern Chile, southern Peru, western Bolivia, and northwestern Argentina occurs in arid zones at altitudes as high as 4,600 meters. Because surface water supplies are meager, new mines require unexploited sources of water. Prolific groundwater aquifers occur in salar basins in this region of the Andean Highlands. Exploration water wells have been constructed and aquifer characteristics have been tested in eight salar basins. Results indicate groundwater quality is good. Aquifer transmissivity and storage computed from results of pumping tests indicate maximum production water well capacities in excess of 170 liters per second.

Jan 1, 1982

By Ulrich O. Lange

Coal is America's most abundant energy resource. Therefore, it IS logical to assume that coal must be produced in much greater quantifies in order to make the United States self-sufficient, as far as energy is concerned by 1985. However, there are a number of obstacles which have to be overcome in order to achieve such a great task. According to one of the most outspoken American Mining men, there are three major obstacles. Those are: (1 ) Mining technology (2) Public image of the coal mining industry (3) Governmental policy toward the mining industry The following will be dealing with Shortwall Mining, which is a very specific part of mining technology and which might influence the image of the coal mining industry as well as the governmental guidelines, at least to make it easier to live with those guidelines. During recent years the operation of coal mines has been more expensive than ever. Since 1970, the cost of producing coal increased by 30% and the productivity dropped by just about the same amount. Those are alarming signs.

Jan 1, 1975

By Todd Kilduff, James Grillo, Shrey Arora

In efforts to improve ingress/egress from the existing subway platforms in PATH’s Exchange Place Station, a new 18-foot horseshoe cross-passage tunnel was constructed by Walsh Construction who retained Kilduff Underground Engineering for design of the initial support system and to install and maintain geotechnical instrumentation. The project presented some unique challenges as a result of the proximity to pedestrians on the platform. PATH service remained uninterrupted, limiting the Contractor to mechanical means of excavation to advance the heading. The logistics proved very challenging for the approximate 100-foot-long tunnel excavated in soft Manhattan Schist. This paper will present the design and construction challenges for the project.

Dec 1, 2022

By J. C. Irvine

A recent development in underground drilling has been the introduction of the down-the-hole drill, an old and very familiar tool to the surface operator. The idea of moving such a rig underground is not new. Tests were conducted at INCO in Canada and Mt. Isa, Australia in the early 1960's, and St. Joe used one for underground exploration in their Missouri lead mines in the mid-1960's. However, the trend to full scale production programs did not start until the mid-1970's. The first successful North American test was at INGO in early 1973. This led to a large-scale pillar recovery and open stoping program which en¬compassed 25 drilling units by mid-1976. Meramec Mining Company tested a unit using air boosted up to 200 psi (140, 000 kg(m2) in the summer of 1973 which by 1976 led to an open stope and pillar drilling program using 12 units. By mid-1976, production units using boosted air were also in use at Pilot Knob in Missouri and at St. Joe in Balmat, New York. Experimental and utility units were in use in several other mines and down-the-hole drills were being seriously considered for at least one major new underground mine.

Jan 1, 1976

By M. H. Pettibone

During the past decade, the size of grin- ding mills has steadily increased. Mills 11 m in diameter with 9 mW motors have been installed with even larger units on the drawing board. The rising costs of energy and labor have spurred interest in improving efficiency while reducing capital investment and operating labor. Autogenous and semiautogenous grinding have experienced renewed interest as efforts to reduce operating and capital costs have increased.

Jan 1, 1981

By W. A. Van Dyk

Hydrophobic particles with diameters between 1 and 3 mm are poorly recovered by conventional flotation techniques. A novel reverse flotation technique is described whereby coarse particles with surfaces rendered highly hydrophobic, repel the bubble films in a froth and thus drop through the froth under gravity, to be recovered as a sink product. Conversely, gangue or hydrophilic particles are supported by the bubble films in the froth and are therefore recovered as a floating product. Tracer tests were conducted in the cell in order to study the dynamic behaviour of solid particles in the froth. The effects of hydrophobicity, density, particle size and particle shape were investigated experimentally. The higher the hydrophobicity of the particles, the lower the recovery of particles as a floating product, while the recovery of particles as a sink product increases with an increase in particle density. Furthermore, a decrease in particle size results in an increase recovery of hydrophobic particles as a floating product. When treating particles of the same mass-to-surface-area ratio in the froth, flat particles would be recovered as a floating product in preference to cubic, disc-shaped, cylindrical and spherical particles, in that order.

Jan 1, 1995

By Gerald C. Smith

Carlin Gold Mining Company is a wholly owned subsidiary of Newmont Mining Corporation and is located 76 kilometers north west of Elko, Nevada. Multiple bench open pit mining methods are being used to mine 24.5 Mt of ore and waste per year. Mining started in 1964 and up through 1983 Carlin has mined 138 Mt of ore and waste and has milled 13.8 Mt of ore. Selective mining of carbonaceous and oxide ores together with a good grade control program have been key factors in the success of the operation. This paper will present the raining methods and the mining equipment being utilized to make Carlin Gold Mining Company a very profitable operation while mining and milling low-grade gold ore.

Jan 1, 1985

By Charles O. Frush

This paper presents a summary of the current employment practices with respect to recent graduates in Mining Engineering, as observed at the Colorado school of Mines. Because our experience is limited to our own group of students it prob¬ably does not correspond exactly to that experienced at other mining schools, but because the Colorado School of Mines graduates approximately 15 per cent of the men in this field our experience is probably representative. We have chosen to limit the information presented here to that pertaining to the period since July 1, 1960. This corresponds to the experience with the class of 1961 and to the experience of the class of 1962 up to the end of the first semester of the senior year. There were 36 mining engineering degrees given in 1961 In a class numbering 43 senior. We expect to give 30 first degrees in 1962 in a class numbering 44 seniors.

Jan 1, 1962

By Francis X. Murray

Synthetic fuels will be the first major development effort to feel the effects of a new set of opposition forces. These confrontations will not be of the same variety as those which occured in the 1970s. Instead the synfuels industry, particularly in the West, will find itself confronting a new coalition of local political, community, and state spokesmen. They will oppose synfuels because the projects will represent a threat to existing lifestyles, political structures, taxes, social life, water rights, economics, and other politically sensitive considerations. In short, they mean change -- usually dynamic, full of unknowns and always threatening. The battles themselves may be fought technically over environmental issues, law and regulations; often these will be the instruments of the opposition. The real underlying problems will likely lie much deeper. In many cases environmental groups will be enlisted as the standard bearers; however, this approach may simply reflect the fact that environmental objections are convenient or at times the only tools at hand.

Jan 1, 1981

By Dominique Francois-Bongarcon

The rational and optimal determination of the design of a mining exploitation is a very intricate and difficult problem : the parameters are numerous, some technical, some economic or technico-economic which cannot be fully controlled; beside, deposits are estimated from very limited information and the choice criteria are not always quantitative, the economic context has to be anticipated by several years, and even the technological limits can change tomorrow. So, although very clever and performing numerical algorithms have been developed in recent years for open-pit design, we consider that this problem has not really been solved satisfactorily until now. The reasons are that people have concentrated their efforts on informatical algorithmical problems, and have assumed that the technical and economical data are well defined at the time of the study, which is generally not true. In particular, the mere fact of assigning dollar- values to blocks in order to maximize the total cash-flow is generally unrealistic because of the uncertainty of the data used. Consequently, the significance of the unique pit obtained as a result of these algorithms is questionable.

Jan 1, 1981

By Paul C. Lingo

The title of my talk today might lead you to two logical conclusions: The industry is faced with a problem that requires a solution and after discussing the problem I will offer a solution. The first conclusion is painfully accurate. One need only look at the accident statistics to be aware of the problem. During the eight-year period 1954 through 1962, the United States Bureau of Mines reports that falls of rock and coal accounted for 1,435 of the 2,516 fatal injuries that occurred in underground bituminous coal mines. Some improvement was made during 1962. For the first time since records have been kept, falls of rock and coal accounted for less than 50 per cent of the underground fatal injuries. The 105 deaths recorded in 1962 indicate that a great amount of work remains to be done in this area. As to the second conclusion, let me assure you at the outset that I have no panacean solution; however, I do propose to discuss some aspects of the problem and some possible methods of solution. What methods of solution are now, or have been employed in attempting to solve the problem? More specifically, what methods have you and your associates used? Has it been an orderly well thought out approach to the entire problem, or has it been a somewhat piecemeal approach which tackled the immediate problem and left the total problem for another day? Perhaps a new approach may be in order.

Jan 1, 1964