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By Michael Mann

Two house trailers and a modem modular house, all pillar-supported with cantilevered perimeters, were monitored for structural response to vibrations from surface coal mine blasts. Due to the large blast site distances, peak particle velocities measured in the ground beside the houses did not exceed 0.32 ips, and airblasts did not exceed 106 dB. However, the structures responded significantly to the ground vibrations, with maximum high-comer amplification factors as high as 8.5 in the horizontal directions. Vertical structural responses were as high as 10 times the vertical peak particle velocities in the ground, but appeared to be driven more by horizontal ground motions. No measurable airblast responses were observed. The natural frequencies of the structures ranged from 5 to 10 Hz.

Jan 1, 2000

By C. Ringas

Pipelines are used extensively in industry to convey various products. Internal corrosion of pipelines can lead to perforation and leakage of the product. A growing problem, not often accurately recognized, is internal corrosion of pipelines caused by bacteria. Microbiologically-induced corrosion (MIC) refers to corrosion caused by a variety of micro-organisms. This form of corrosion is not widely recognized in many industries, although it is widespread and causes many corrosion problems in pipelines, both internal and external. Sulphate-reducing bacteria (SRB) are responsible for the bulk of the corrosion problems caused by MIC. Corrosion caused by SRB is found extensively in water pipelines conveying raw, potable and waste water, as well as in pipelines conveying slurries. This problem also occurs in pipelines conveying crude oil. This paper describes internal corrosion problems of slurry pipelines caused by bacteria and outlines mitigation methods to improve slurry pipeline integrity, thereby extending the life of such pipeline

Jan 1, 2007

By Donald A. Bruce

The paper reviews aspects of the construction and performance of prestressed ground anchors installed in soils and weak rocks. Attention is focused on good practice for drilling, tendon fabrication and handling, grouting, stressing and testing. Regional variations - not always logically justified - are described. The performance of anchors in a variety of geological conditions is illustrated with reference to recent full scale test programs. 1. Introduction In the United States there has been steady growth in the use of prestressed anchors in materials other than competent or hard rock, in the years since their introduction in the late 1960's. This expansion has to a large extent been driven by specialty geotechnical contractors who both imported foreign developments and conducted their own basic researches, in locally prevailing conditions. With such data and experience, these engineers have had the confidence to promote "alternative solutions" for difficult earth support problems to receptive designers and owners. In turn, being engaged in the details of design and performance monitoring has given these parties the close exposure necessary for the real transfer and understanding of the technological concepts, and this knowledge has generated positive feedback for the contractors.

Jan 1, 1991

By Richard Klimpel

"Over the last 15 years, there has been a number of plant scale sulfide mineral flotation tests organized by this author specifically aimed at understanding how flotation rate varies with reagent type and dosage. With regard to the Interaction of collector dosage, particle size, and frother type, the eight specific trends listed in the paper (Illustrated with data from two specific case studies) are qualitatively the same for almost all plants studied in some depth. The Interaction of flotation rate K and equilibrium (Infinite time) recovery R in the plant has been denoted as the R/K trade-off. The effect of collector dosage on the rate of flotation of specific particle size intervals is particularly interesting and once understood, is quite useful In understanding how industrial flotation plants respond to changing reagent type and dosage. The location and magnitude of the R/K trade-off can be different for various ores and various plant configurations, but the RIK trade-off is almost always present. The purpose of this paper is to clearly describe and illustrate the nature of this very Important flotation system Interaction so that operating engineers have a starting reference point for beginning successful plant Improvement studiesIntroductionIt is well recognized by industrial froth flotation plant operators that improving existing sulfide circuit performance is often difficult due to the self-compensating systems nature of the froth flotation system, e.g. Klimpel (1988, 1989, 1995). Extensive plant testing with existing and new reagents by this author throughout the world has clearly shown that one of the more important self-compensating mechanisms is the Interaction between collector dosage, frother type, and particle size. The term self-compensation in flotation simply means that as the plant operator consistently changes one parameter in the same direction, the nature of the froth flotation system Is such that the circuit will eventually begin to resist this controlled parameter change by automatic (uncontrolled) changes In other parameters and the overall circuit performance will go through a maximum or minimum (hence causing the operator to stop the parameter change)."

Jan 1, 1997

By W. David Tyler

Any mining or engineering-construction excavation that extends below the water table must be dewatered. In many situations, the ground is of low permeability or the workings extend only a short distance below the water table. So water removal can be handled easily and economically by using mobile centrifugal pumps. However, there is an increasing number of mines that have a continuous high flow of water into the workings. Controlling this flow can significantly increase the cost of ore production. Successful implementation of any major dewatering scheme will ultimately rely on a clear understanding of the local geology. This understanding is necessary before an interpretation of ground water conditions can be made. It will dictate which dewatering methods are feasible. Once the geology and the ground water system are known, the scope and timing of the dewatering measures can be varied with the mine plan. Ground water modeling can assist in optimizing the dewatering system, though the precise objective of each model should be clearly defined. Production wells must be sited and drilled so that individual well efficiencies are high. Any lost efficiencies will translate into higher operating costs. Each well must be designed for maximum long-term control of the water table, and pumps sized to operate under continually changing heads. Finally, the investment in each production well must be protected during the mining process.

Jan 1, 1991

By C. Vipulanandan

It is critical to monitor the ground conditions during excavation and drilling of boreholes during construction to identify possible changes in the soil and rock formations. Drilled shafts are increasingly used as foundations to support structures, bridges and other facilities in geomaterials such as soft-rocks and hard clays. Locating the bottom of the borehole during construction with the required design strength is critical. Hence developing a simple device that could be easily adapted/used with the drilling tool was of interest in this study. Determining the shear strength of the geomaterial in the borehole and at various elevations including the bottom of the borehole can lead to better quality control of construction by identifying the various layers based on strength. In this study, a down-hole penetrometer (DHP-CIGMAT) was designed, built, calibrated and tested in the field to determine its effectiveness in measuring the strength of soil/soft rock in the boreholes. Based on limited field tests, linear correlations between geomaterial strengths and DHP-CIGMAT deflection have been developed. The DHP-CIGMAT can be used to identify soils and soft rocks.

By Adrian Moore, Alan Richards, Andrew Brodbeck

Structural blast vibration limits should be based on the strength of the structure, the stress induced by blasting, and a responsible factor of safety. In this paper a methodology that uses direct strain measurements to determine the stress induced by blasting is described. The methodology has been used to measure strain resulting from blasting, and establish appropriate blast vibration limits on a brick sewer tunnel, an underground mine heading, brick veneer houses, a water pipeline, and transmission tower foundations. An outline is given of the use of the methodology to establish limits for the main entry heading of an underground coal mine, and transmission tower footings. The methodology that is described has reduced uncertainty factors, and permitted the specification of higher blast vibration limits than had been previously used.

By Roberto Folchi, Hans Wallin

Having so many norms and technical content of legislation to deal with is a problem that an explo-sives engineer has to face, especially when working at an international level. Each country has its own norms and legislation, sometimes even each other region or state, as if the physics of explo-sions, rock, concrete, and masonry characteristics would change across the borders. Both norms and laws are frequently out of date, being mainly developed at the beginning of the previous century and adjusted, piece by piece, to a technical and political context that is constantly changing, with adjustment being frequently adopted in a hurry, due to a problem arising such as that of internation-al terrorism. Sometime also, norms are not harmonized with those they intend to amend, so required explanations and new adjustments lead to a vicious circle that increases confusion, complexity and depresses the explosive industry.

Jan 1, 2015

By Charles Knilans, Tassos Grammatikopoulos, Nicole Hoffmann

"Twin Metals Minnesota LLC, (TMM) has recently completed a prefeasibility study evaluating the development and operation of an underground copper (Cu), nickel (Ni), platinum (Pt), palladium (Pd), and gold (Au) mining project on the Maturi deposit in northeastern Minnesota.The Maturi deposit is a magmatic Cu-Ni-sulphide deposit occurring along the basal contact of the South Kawishiwi intrusion, comprised of heterogeneous troctolites to gabbros forming a tabular body designated the BMZ (basal mineralized zone). These rocks provide the major gangue mineralogy (plagioclase, olivine, and clinopyroxene) with local, minor rock-forming orthopyroxene, biotite, magnetite, and ilmenite. Altered silicates exist within local fracture and/or alteration zones, which are commonly associated with minor faults in the regional area. The Maturi deposit is comprised of four main mineralized zones within the BMZ, referred to as Stage 1, Stage 2 (S2), Stage 3 (S3), and Upper Heterogeneous. Chalcopyrite, cubanite, pentlandite, and pyrrhotite are mainly hosted within the S2 and S3 units, with talnakhite frequently occurring within the S3 unit.A cross-discipline approach combining geology, geochemistry, metallurgy, QEMSCAN™ mineralogy, and mine planning has been implemented to develop a preliminary geometallurgical model and life of mine metallurgical performance forecast. This paper provides an overview of the methods that were used to develop the model and forecast, and discusses the advantages of such a model in project development and evaluation.INTRODUCTIONThe TMM Project proposes mining a copper-nickel-palladium-platinum-gold-silver (Cu-Ni-PGM) magmatic sulphide deposit situated in the Duluth Complex of northeastern Minnesota, USA. The prefeasibility study proposes a 45,000 million tonnes per day mine and concentrator facility to produce two saleable concentrates. The mine will access two separate deposits, Maturi and Maturi Southwest. Saleable concentrates are the final products of the sequential flotation plant where a high grade Cu concentrate is produced followed by a Ni concentrate."

Jan 1, 2015

THE 125th meeting of the Institute was held in New York, Feb. 20-23, 1922, inclusive, and was the most successful annual meeting of the Institute ever held; there was a larger registration, there were more sessions of importance, and a greater number of sessions, than in any previous year. The total registration was 1331, comprising 351 New York members, 393 visiting members and 587 guests. At the annual business meeting of the Institute, held on Tuesday, Feb. 21, with President Ludlow presiding, there was a much larger attendance than usual. The report of the tellers was read and the following officers were declared elected: Arthur S. Dwight, Director and President-District 0 J. V. W. Reynders, Director and Vice-president-District 0 A. R. Ledoux, Director and Vice-president-District 0 Charles F. Rand. Director-District 0 George D. Barron, Director-District 0 William H. Bassett, Director-District 1 Thomas B. Stearns, Director-District 8 William Kelly, Director-District 5

Jan 3, 1922

By D. A. Norrgran, J. A. Wernham, D. E. Walsh

A qualitative test program was sponsored jointly by the University of Alaska and Eriez Magnetics, in order to study placer gold nugget recovery using an eddy-current separator. Various gold nuggets from Alaska, ranging from 6.4 mm to 63.5 mm in size, were tested. All testing was performed using an Eriez Laboratory ESC, Model REA, fitted with 2000 gauss, surface field strength magnetic rotor. The belt speed was set to 91 meters per minute and the rotor speed was set to 2500 rpm in the forward direction. The splitter was adjusted to just reject the largest pieces of rock that measured an average 76 mm x102 mm x 127 mm. Based on the results of this limited test work, it can be recommended to placer gold mine operators, that Eriez Magnetics ECS technology is a viable and practical concentration technology for coarse gold recovery. Silver and platinum were also tested.

Jan 1, 2003

By B. Caro Vargas

The Toulon South Tunnel in France is the second part of a project started 20 years ago. After the problems and delays suffered during the construction of the North Tunnel, due to a complex geologic context of highly fractured and soft rocks under a highly urbanized environment, a very dense automatic monitoring system was implemented to control the settlements of surface (more than 1000 points), the structures adjacent to the tunnel alignment and the underground galleries being constructed. The latest automatic instrumentation systems were installed, using for example AMTS capabilities in terms of ?automatic prismless settlement monitoring?. All the data (geotechnical, structural and geological) was gathered in a global automatic data acquisition system and continuously available on a web based interface. Three different threshold levels (notification, anomaly, alert) were set up, each one with a differential and an absolute value for settlements. Depending on the actual geological site conditions and the actual monitored settlements, different supporting systems and excavation techniques were used. Furthermore, the monitoring data was also used to predict and anticipate the future settlement, by comparing it continuously with the theoretical Peck settlement curves. This method allowed a better risk management by limiting the settlement on existing structures and helped to secure the Works progress schedule, for a project that lasts from July 2007 to March 2011. The implementation of this observational method application is presented in this paper.

Jan 1, 2012

By P. Ventura

Reliability of the liquefaction analysis is based on data plotted as by piezocone, as by deep vibrocompactation monitored tests. The negative porewater pressure, re lated to hydrostatic value, recorded by piezocone, is a good marker of the absen ce of the liquefaction. Systematic measures of the ground settlements, inside the vibroinfixed steel pipe, allow to locate the liquefable strata with loose density. Experimental study of the combined soil improvement by stone columns is carry out in particular in sea bed. The interaxis of the columns for the best efficiency is valued as of the vibrocompactation, as of the drainage effects, especially during earthquake.

Jan 1, 1989

The process of pile driving disturbs the soil around the pile. The nature and magnitude of disturbance depends upon 1) the pile size, and 2) the nature of soil. Therefore, the prediction of a single pile behavior based on soil properties of undisturbed soil samples may not match its performance. Under lateral loads, the pile may loose contact with the soil near the ground surface especially in clays. The soil pile interactions are influenced the most by pile behavior in this zone. This situation further affects the tally of prediction and performance. Piles are used in groups. The zones of overlapping stress from one pile to the other both around the pile and below their tip particularly in soft soils, contribute to group effects. Empirical solutions have been developed for prediction of the pile group behavior. The group action is more involved under vibrations. Several cases of single piles and pile groups under static and dynamic loads from published records have been analysed. It has been shown that single pile test is the best source of information on the soil-pile-soil interaction effects.

Jan 1, 1989

By G. M. Kintz

"Methods and costs of rock-dusting bituminous coal mines have been discussed in various publications by the United States Bureau of Mines and others.3 This paper discusses the present methods and cost of dusting at the Swastika mine of the St. Louis, Rocky Mountain and Pacific Co., Raton, N. M.In the Swastika mine the recommendations of the United States Bureau of Mines with regard to rock-dusting are followed at least as well as in any mine in the States of Wyoming, Colorado, and New Mexico. This mine is located at Swastika, N. M., approximately 4 miles west of the town of Raton and is in the Raton coal seam. The mine is rated as gassy and produces approximately 1,000 tons of coal per day.A mining system known as the ""room-and-pillar with cut-offs"" is used which results in recovery of nearly 100 per cent of the coal. The mine employs approximately 250 men.Ventilation is maintained by a Sirocco fan so arranged that the air current may be reversed and exhausting approximately 130,000 cubic feet of air per minute at 3 inches water gauge. This fan is supplemented by two auxiliary fans for emergency use. Three main entries penetrate the hill in a straight line for approximately 8,000 feet. The haulage is through the center entry, which is also used as the intake in conjunction with a two-compartment concrete-lined shaft located at the end of the entries. The main return for 3,000 feet inby the fan is 12 feet wide and 7 feet high. For this distance the ribs have been reinforced by a wall made of coke-breeze blocks plastered over with cement. Solid concrete blocks are used for the top row of blocks of the wall. Steel 10-inch I-beams spaced 40 inches apart center to center are supported on these solid blocks and thus support the roof. The next 1,000 feet inby has the same area, but the cement blocks extend to the roof, as no crosspieces are needed. The airways are kept clean and well rock-dusted.A rather unique system is used to handle gas feeders along the intake and haulage entries. There these feeders occur in the roof or where gas is apt to collect in high points along the haulage, tin funnels as large as 3 feet in diameter are placed near the roof. From these a 2-inch or other suitable-sized pipe is run into the return through the wall of the nearest break-through. A valve on this pipe line controls the amount of air pulled. These devices keep the high places clear of any gas, even when strong feeders are encountered.Fifteen-ton electric trolley locomotives are used on the main haulage and approximately 30 roller-bearing oars, each having a capacity of approximately 3,000 pounds of coal, compose a trip. All loaded tripe carry steel drags on the last car, and automatic derails are located at advantageous points throughout the mine.All loaded trips are thoroughly sprinkled on the sectional partings and at the main parting. The track is sprinkled every idle day, or if needed, every day; from a large tank mounted on a truck hauled by a motor. Neither nozzle nor spray is used, as these were unsatisfactory. The water leaves the tank. through a 11/2-inch valve and is permitted to flow on the road through a horizontal 11/2-inch T. Water is obtained from filling stations located throughout the mine. It is stated by the officials that the use of this method of sprinkling permits the entire haulage roadbed to be wetted down in two hours."

Mar 1, 1930

By P Steinier

Most operations, when considering their comminution circuit, are primarily concerned with achieving the desired particle size distribution to obtain adequate liberation for the separation process, at minimum cost. Invariably, the effect the grinding media has on the subsequent separation process (ie flotation, leaching) is not taken into account when selecting the media. This choice is driven by cost rather than metallurgical outcomes. Maximising valuable mineral recovery, with optimum selectivity against gangue minerals, is about good particle preparation. And, particle preparation is strongly related to achieving adequate mineral liberation with the correct pulp chemical conditions. However, the pulp chemistry of a system is largely ignored and relies heavily on pH control and the addition of appropriate reagents (collectors, frothers, activators, depressants). The changes effected by the addition of the various reagents are obtained through conditioning the ground pulp prior to or during the concentration stage, subsequent to grinding. Frequently, reagents are added during grinding with good effect, but the impact of the grinding media on down stream processing is usually overlooked. A number of case studies examining the effect of grinding media on pulp chemistry and subsequent flotation performance were completed on several different sulfide mineral systems (for example, lead/zinc, copper, refractory gold). The evidence suggests that a change in grinding media type from forged to high chrome (ie conditioning the pulp during grinding) resulted in a shift in pulp Eh to less reducing conditions, an increase in the dissolved oxygen content of the pulp and a reduction in the iron species present. The changes have a positive impact on flotation behaviour. The results of the case studies are discussed.

Jan 1, 2004

Elongates are commonly used as stope support in South African gold and platinum mines. To evaluate the effect of the inherent strength, stiffness and yield variability associated with elongates, a statistical method is presented which addresses and quantifies the support performance at various levels of certainty. The analysis, which is based on a normal distribution, makes use of force-deformation curves determined from multiple laboratory compression tests on the same support type. The applicability of the method is illustrated making use of actual performance capabilities of various types of elongates. In order to ensure a high probability that support units installed underground exceed the standard support performance curve established by means of laboratory tests, the statistical mean of a suite of tests based on the same support type is downgraded. The ?correction factor? is a function of the mean and standard deviation of the test data, as well as the sample size of units deemed to control the local rock mass stability. It is shown that downgraded performance curves based on a high probability (90 to 95percent) of support units exceeding this performance level are suitable to ensure that the design of support systems will in variably meet the design criteria. In the highly discontinuous hangingwall rock mass typically associated with intermediate- and deep-level mining operations, the interaction between adjacent support units is comparatively limited (at the support spacings commonly used). Therefore, the appropriate sample size (n) of the support units controlling the local rock mass stability should be n= 1. In shallow mining conditions, sample sizes of up to n=5 may be warranted, depending on the spacing of joints and other discontinuities in the hangingwall.

Jan 1, 2001

By Edward H. Jr. Boyle, Paul R. Thomas

Introduction It is estimated that nearly 40% of all the gold ever mined in free world countries has been produced by South African operations. There is concern that this immense productive capacity will soon decline. Such a decline could reduce world gold supply and lessen the ability of market economy countries (MEC) to exert the major influence upon the world gold market. This paper addresses three general issues concerning South African gold production: • How much gold remains to be recovered from the demonstrated resources of the 44 evaluated South African mines; • How long can production at current levels continue; and • What will be its cost. Table 1 provides production data on the world's 10 largest producers for the years 1971, 1981, and 1983. As shown, South African gold production declined significantly from 1971 through 1981. As of 1981, annual South African gold production had dropped by more than 311 t (10 million oz) in 10 years. Despite this, its mines still produced 656 t (21 million oz) that year, about half the world total. From 1981 through 1983, this trend was reversed. Annual South African gold production increased by more than 21.8 t (700,000 oz). The trend reversal was also evident in the US, Canada, and Australia. This illustrates the general, inverse relationship between gold price and gold production. In South Africa especially, as gold prices increased substantially during the 1970s, the average grade of ore mined (pay limit) was lowered as new, lower grade areas and materials were exploited. Gold production declined in volume. But gold revenues increased, and the lives of the operations were extended. The 1981-83 period was one of declining (US dollar-based, average annual) gold prices that resulted in increasing South African production as average ore grades were raised. South Africa currently accounts for 50% of world production (Fig. 1). Figure 2 illustrates South Africa's contribution to total MEC production in 1971 and 1983. Although South Africa's relative share of production has declined, it still represents the single most important source of new gold supply. In 1983, it supplied more than 65% of total MEC production. South Africa currently produces more than twice as much gold as the Soviet Union (ranked second in world production), and 11 times more gold than the US (ranked fourth in world production). Barring major discoveries, South African gold production is expected to peak in 1987 and begin to decline again throughout the 1990s. The rate of decline is ex-

Jan 11, 1984

By T. Gammatikopoulos, C. Gibson, M. Aghamirian

Lithium is an alkali metal found in brine deposits in the United States, Chile and Argentina, as well as in hard rock deposits in Australia and North America. In hard rock deposits, spodumene (LiAl(Si2O6)) is the major economic lithium bearing mineral. Spodumene is typically upgraded through a combination of dense media separation, flotation and magnetic separation. One of the major spodumene concentrate quality specifications is the iron oxide content because it will help determine if the concentrate is considered ceramic grade for use in ceramics and glass or chemical grade for use in lithium ion batteries. The rejection of iron bearing silicate minerals from artificial ore composites (high amphibole and low amphibole, high quartz/feldspar) from a hard-rock spodumene deposit was investigated using magnetic separation and flotation. The efficacy of Wet High Intensity Magnetic Separation (WHIMS) in iron rejection was found to be dependent on the mineralogy of the iron-bearing silicate minerals including modal distribution, liberation and association. When magnetic separation was conducted prior to flotation, the Fe2O3 grade in the final flotation spodumene concentrate was reduced from ~3% to ~1% Fe2O3 , and improved lithium recovery in flotation was observed. It was determined that it was most effective to conduct WHIMS on the flotation feed after scrubbing and de-sliming because this reduced the required magnetic field to recover iron-bearing minerals, likely because slime coating was greatly reduced. Flotation collector screening of four different collectors with varying rosin acid content demonstrated a potential increase in selective flotation of spodumene over some iron silicate minerals with decreasing rosin acid content in the fatty acid collector. However, due to marginal difference in flotation results with the various collectors tested, further testing is required to confirm the observations made and establish a hypothesis regarding the effect of rosin acid content.

Jan 1, 2017

By L. A. Readdy

Pilot Hole "X" was drilled to test the formations through which the ventilation shaft for the proposed U.S.B.M. demonstration oil shale mine will be drilled. The history of the drilling of Pilot Hole "XI' is presented. This historical summary provides the details of method used during the drilling of this hole. Problems encountered during drilling are discussed. The quantities of drilling mud and other materials used to drill the hole are documented.

Jan 1, 1977