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By H. F. Haller, H. C. Pattison

The research program described in this paper is sponsored by the Advanced Research Projects Agency of the Department of Defense and monitored by the Bureau of Mines, United States Department of the Interior. PROGRAM DEVELOPMENT While Holmes & Narver is better known in other fields, the company has been active in many phases of underground excavation for over twenty years. In the 1950's, H&N participated in design and construction of nearly twenty miles of waste disposal tunnels in Southern California. As Architect-Engineer for the Atomic Energy Commission, we had design and management responsibility for many miles of tunnels and for thousands of feet of exploration and big hole drilling, from coast to coast in the States, and for gas well completions and exploration drilling for the Navy and the National Science Foundation from Pt. Barrow to Byrd Station in Antarctica. In my ten years with the company, we contributed to the development of big hole drilling techniques at a number of sites and analyzed the capability of boring machines for many of the tunnel projects. In a 1965 engineering study of a hundred miles of vehicular tunnels in rock under New York City, we investigated

Jan 1, 1997

By R. Karl Zipf, Z. T. Bieniawski

"Researchers at The Pennsylvania State University are engaged in a project to understand the mechanics of respirable size fragment formation in coal. The project is based on the premise that a thorough understanding of the fundamental mechanics of fine fragment formation may lead to techniques for reduction and better control of coal dust problems in mines. Presently, it is believed that the mode of fracture propagation which can range from pure tensile to pure shear or any mixed mode in between and the loading or displacement rate can influence the amount of respirable size fragments that are generated on new fracture surfaces during the fracture propagation process The essence of any coal cutting process is one of mixed mode fracture propagation. To study the crack propagation process, a unique mixed mode testing rig was designed and fabricated. This rig is capable of applying loads to a prenotched test specimen that range from pure Mode I (tensile mode) to nearly pure Mode II (shear mode) or many mixed mode loading combinations. It is also possible to apply different loading or displacement rates to the test specimen. With this rig, it is possible to create new fracture surfaces via the different fracture modes and under various loading conditions.These new fracture surfaces are examined with a scanning electron microscope (SEM) to characterize the amount of structural damage and respirable size fragment formation that occurs during the fracture process. Initial observations suggest that the amount of fine fragment formation and the new fracture surface appearance is related to the fracture initiation conditions, particularly the fracture mode and the loading rate. Mode II loading and higher loading rates seem to generate more structural damage and respirable size fragment formation that Mode 1 loading at slower rates.With the mixed mode test rig, the mechanics of fracture initiation for a single crack can be controlled to better understand its influence on respirable size fragment formation. Such understanding may lead to methods which characterize the tendency of specific coal seams to produce undesirable fine fragments during the fracture process, or it may lead to rational recommendations and design guidelines or coal mining machines which inherently produce less dust.IntroductionAs part of a larger effort to reduce the incidence of coal workers pneumoconiosis (black lung) in coal miners, researchers at The Pennsylvania State University are engaged in a project to understand the fundamental mechanics of fine fragment formation in coal. This project is part of a com¬prehensive research effort within the Generic Mineral Technology Center for Respirable Dust which is jointly administered by The Pennsylvania State University and West Virginia University.The principal source of the coal dust in underground mining is the cutting operation. The U.S. Bureau of Mines (USBM) and various European research organizations have conducted investigations into the mechanics of coal cutting for many years. These studies of airborne respirable dust (ARD) formation have concentrated on empirical studies of the various cutting parameters and their effect on ARD for¬mation. The parameters study include depth of cut, cutting speed and bit spacing.(1,2) Other studies investigated the effect of symmetric and asymmetric bit wear and various bit geometries and designs (3-5) Roepke(6) summarized the principals of proper coal cutting to minimize dust formation by recommending to ""cut at maximum depth (maximum advance rate) at all times, at minimum RPM, with the fewest possible bits, having the lowest possible included tip angle."" Most coal in the U.S. is mined with the continuous mining machine which inherently cannot meet these design recommendations.(3)It is recognized that respirable size dust particles are formed and/or liberated by a fracture process. One extremely interesting and useful study performed very early in the USBM dust re"

Mar 1, 1989

By E. K. Stanek, P. Kantabutra, R. A. Wolf

This paper summarizes the cause and effect of induced voltages in multiple conductor cables supplying alternating current power to equipment in under- ground coal mines. The investigation of this phenomenon revealed that the electrical energy produced by the resultant electric arcing between the frames of mobile electric face equipment was of a sufficient magnitude to ignite explosive methane-air mixtures. The results of laboratory tests and field tests made between equipment frames during actual operation in numerous coal mines are discussed. Several methods of eliminating or suppressing the induced voltages to nonincendive levels are also described. It is the purpose of this paper to convey to the mining industry a knowledge of this problem and to recommend methods of eliminating or reducing these induced voltages or arcing currents to safe levels.

Jan 1, 1975

By Fleming GJ

The Miwah prospect lies on the dilational 070¦ trending Miwah Lineament near its intersection with northerly oriented fractures within Pliocene volcanic rocks exposed between a NW trending segment of the dextral transcurrent Sumatra Fault, and the more northerly trending Samalanga-Sipopok Fault to the east. These faults reflect the continued interaction between stresses from the India-Australia plate located to the southwest, and spreading within the Andaman Sea to the north of Sumatra. A system of deep seated faults is believed to have facilitated emplacement of post-Miocene magmas and Quaternary volcanic centres at shallow crustal levels throughout northern Sumatra.

Jan 1, 1995

By R. W. Stahl

Coal mining has been revolutionized by the continuous miner. This machine has replaced, or has combined into 1, 3 former operations: Cutting, blasting, and loading. During the 25-year period before this machine was introduced, advances had been made in transportation, but the actual "coal getting" remained virtually the same. As frequently occurs, the multiple-purpose continuous miner introduced a new hazard--more rapid liberation of methane. The coal output formerly obtained from 10 to 20 working places might now be obtained from 1. It is true that circulation of air was generally increased; but the bulk of this machine virtually precludes continuous flow of air across the face, where gas may accumulate. Apprehension about this possible hazard led the Bureau of Mines to test face atmospheres during operation; and Report of Investigations 5288, Methane Buildup During Cutting and Continuous Mining Operations (published in 1956), presents proof that real danger may be present in many otherwise well ventilated mines.

Jan 1, 1958

By W P. Breytenbach

"The phased application of statistical process control (SPC) infers that processes are classifiable as pre-SPC (or phase zero), phase I and phase II processes, with different objectives being pursued in the different phases. Phase zero processes, defined as processes affected by assignable causes of variation, are characterised as follows: out-of-control with unknown autocorrelation structure having an unknown statistical distribution not performing consistently on target with minimum variability potentially incapable of conforming to the product specifications. The objectives of phase I SPC is to obtain estimates of the mean (µ), variance (s2), probability density function (f(X)) and the autocorrelation structure, as well as transforming the process into a phase II process (defined as a process conforming to specifications and performing on target with minimum variability). As in any other type of research or pragmatic improvement intervention, sampling is required is to achieve these objectives. The challenge of deciding a phase I sampling plan is multifarious since it has to cope with the aforementioned effects of assignable causes and provide for rigour estimates of the unknown parameters. Furthermore, deciding sampling plans in phase I invariably presents a classical catch-22 situation: appropriate sampling is required to determine the autocorrelation structure of a variable, but knowledge of the autocorrelation structure is required to formulate an appropriate sampling plan. This paper suggests, for random variables, guidelines to formulate sampling plans, and presents a methodology to estimate the inherent process parameters of process variables and an approach to identify assignable causes in phase I. CITATION:Breytenbach, W P, 2014. Rational sampling and standard deviations for random variables in phase i application of statistical process control, in Proceedings Sampling 2014, pp 141–154 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 29, 2014

By Gary A. Campbell, William A. Vogely

INTRODUCTION The theory of mineral demand often is slighted in the study of mineral economics. The supply side of the mineral industries usually commands a great deal more attention and effort by mineral economists than the demand side does because the study of mineral supply includes topics such as exploration, resource availability, and exhaustion theory that are generally considered unique to the mineral industries. Mineral demand, on the other hand, is thought of as being more general in nature and therefore of less concern to mineral industries specialists since it is similar to the demand for other inputs of production. This similarity with other inputs of production, however, does not negate the importance of a thorough understanding of mineral demand. It is the interaction of supply and demand that determines market behavior and not supply alone. Mineral demand is a key component among the factors that influence mineral production; there- fore, a good understanding of mineral demand can give one better insights into the industry behavior and trends than one would otherwise have. A strong working knowledge of the demand side of the mineral industries is a powerful tool for analyzing and predicting mineral market behavior. The material presented in this chapter does not depend on any special background in economics and should be accessible to all interested readers. The chapter is organized so as to permit an orderly progression of the basic topics of the theory of mineral demand while allowing digressions on related issues of special interest. The first section of the chapter is on the determinates of mineral demand. The discussion be- gins with the introduction of consumer demand and some of the necessary terminology of economics and proceeds to the particular case of the derived demand for an input of production such as minerals and the characteristics of such demand. The second section of the chapter is on the response of mineral demand to changes in economic variables like price and aggregate income. This second section of the chapter be- gins with a general presentation of elasticity of demand and continues with the particular case of the price responsiveness of mineral demand and its nature in the short and long-runs. A brief look at the response of mineral demand to price changes for other products is also included. The chapter concludes with a discussion on the effect of aggregate income changes on mineral demand and its nature in the short and long-runs.

Jan 1, 1985

By Timothy D. Stark

Jet grouting has increasingly become a ground improvement technology used to address seepage concerns and provide strength improvement to soils underlying dams. The technique of jet grouting uses high pressure/volume jet fluids to erode existing soil, evacuate some or most of the soil, and mix the remaining cuttings with cement slurry to form soilcrete. While considered a useful technology, this paper discusses some of the problems that can develop while jet grouting in or below a dam with an operational reservoir and seepage condition. Jet grouting experience at Tuttle Creek Dam indicates concerns with respect to ground fracture; spoil return, column diameter consistency, and homogeneity of resulting soilcrete. Recommendations are presented to increase monitoring of downhole parameters during jet grouting to better understand the downhole pressures and soil response during jet grouting.

Jan 1, 2012

The Empire IV expansion is on schedule for completion in January 1980; Hibbing Taconite's 2.7 million ltpy* expansion should be finished late in 1979; and Reserve Mining's tailing disposal project is on target for April 1980. Erie Mining Co., the first to bring 170-ton haulage trucks to the Mesabi Range, reports excellent operating results, and Inland Steel expects to produce 80% of its pellets in 1979 using coal rather than oil. One Michigan mine has so many inspectors that it has hired a school bus to transport them around the operation; and a contractor reports that mine construction projects of the future may require the training of 15,000 workers. All of this was covered at the 52nd Annual Minnesota Section AIME Meeting and the 40th University of Minnesota Mining Symposium, a joint event held each January in Duluth.

Jan 3, 1979

By Yanhui Sun, Yanan Zeng, Kaike Cai

"Hot ductility of Nb-V-containing steel has been studied by theoretical calculation and thermal simulation experiment. Meanwhile, microsegregation and precipitates were analyzed. The results showed that segregation degree of elements S, P, 0 is greater in mushy zone, while, the hot ductility was deteriorated by inclusions of Fe(S,O), (Fe,Mn,Si,Al)(S,O) in the interdendritic region. At the temperature 1100°C, a few NbN particles, 60-70nm, have little effect on mechanical property. In the temperature range 1000°C to 975°C, R.A declined rapidly from 82.36% to 69.61% with the diameters decreasing from 20 to 10nm and quantity of particles increased 23 to 45inds/µm2, respectively. In the temperature range from 900°C to 850°C, R.A reduced unobviously from 34.27 % to 30.01 % with ferric films thickening gradually. The critical stress, 52.38MPa, was equal to tensile strength at 975°C. Intergranular fracture was easy to occur with higher critical stress below 975° C.IntroductionProductivity and product quality of slab are seriously affected by cracks during continuous casting and the influencing factors of cracks are various[l]. From microcosmic angle, resisting deformation ability of initial solidification shell decreases obviously with solute elements segregation which can urge the low melting point ofliquid film to form at grain boundaries[2, 3]. Meanwhile, with temperature decreasing, particles would precipitate as the practical solubility product is greater than equilibrium solubility product. The carbonitrides would lead to stress concentration at austenite grain boundaries. Therefore, the transverse cracks of microalloyed steel would form during the straightening operation in the continuous casting process. The hot ductility of steels in the temperature of mushy zone was characterized by microalloy elements segregation, zero strength temperature (ZST) and zero ductility temperature (ZDT). The nature, shape, and size of precipitates have been investigated by TEM (JEM2100). Hot tensile test with low strain rate was simulated by Gleeble-1500. The objective of present study is to provide reference for zero defect of microalloyed steel during continuous casting process."

Jan 1, 2013

MAXIMINE is a compiled, comprehensive, spreadsheet-based, macro- driven software package, written to aid in the rapid and early assessment and design of virtually any small, medium, and large mining or quarrying project. The system has been des

Jan 1, 1998

By Sudhir C. Dhara

An attempt has been made on the concentration of Platinum Group Metals (PGM) from the converter matte material by microbial .leaching. Biological oxidation of base metal sulfides such as iron, copper, nickel and free sulfur present in the matte material using Thiobacillus ferrooxidans is an alternative method to concentrate the PGM-and gold. The method which produces a platinum group metals concentrate is comparable to chemical processes and electrochemical process.

Jan 1, 1995

By L. W. T. Weitzel

"This paper reviews the Falconbridge- SMRQ’s Raglan project in northern Quebec and the process that was used in developing its current long-term mine plan. Challenges were many and not only limited to the longevity of the project, numerous ore deposits (both underground and open pit), and a 40 km property strike length. As a result of its remote northern location, other factors such as progressive reclamation, leachable mine waste, water treatment, and waste management were also part of the plan. A combination of modern planning tools were used to formulate the plan including DataMine, Mine 2-4D, AutoMod Simulation, and an Excel-based financial spreadsheet to bring the total plan together. The focus of the paper is to show the complexity of modern mine planning and associated economic modelling of mine processes. IntroductionThe Raglan project is located 1660 km directly north of Quebec at the northern tip of the Quebec Peninsula in Nunavik. The main property is 40 km in length stretching from the Donaldson airport area at the eastern edge of the property to East Lake at the western edge. The Deception Bay port is 90 km north of the main complex/mill situated at Katinniq which lies approximately in the middle of the property (Fig. 1). The mine processes 1 000 000 tpy of ore from both open pit and underground sources. The mill is forecasted this year to produce more than 150 000 t of concentrate grading more than 18% nickel. All personnel and critical cargo are transported to the site via a company-leased 737 jet from Rouyn-Noranda where the main administration office is located. The majority of cargo is shipped to the site via Deception Bay from Quebec and on the return trip, nickel concentrate is shipped back. From Quebec, the nickel concentrate is sent by rail to the Falconbridge smelter in Sudbury and on the reverse rail haul, nickel matte from the smelter is sent to Norway via Quebec."

Jan 1, 2003

By N. Mohan, A. K. Biswas, V. Y. Sampat Kumar

At low sodium-oleate concentration, calcite flotation is substantially improved by the use of CO2 instead of air. Electrophoretic mobility measurements indicate that carbonation results in the accumulation o f positive charge on the calcite particles. This heightens adsorption of oleate anion, an effect confirmed by tracer-technique measurements. Fundamental insight is obtained as to how CO2 serves better as an activator than some mineral and organic acids, how oxalic acid acts as a depressor, and why the influence of Ca++ ions, liberated during carbonation, on flotation behavior of calcite is insignificant and sometimes adverse.

Jan 1, 1972

By Howard Steven Strouth

The Blind River mining camp in Canada is all set to stage a major revolution. Enthusiasts on the scene say it will bring large-scale mining to North American uranium operation. If orebodies already discovered live up to their promise, it will be anything but the usual business of a few men handpicking orebearing rock out of small mines. Because of the geological structure of the region referred to generally as the Algoma district the ore may prove an extremely lucrative enterprise for years to come. The present center of activity is in Ontario about 75 miles east of Sault Ste. Marie, and just north of Lake Huron. It stacks up as one of the large uranium discoveries in the Western Hemisphere. For a change modern mining machinery working against large ore faces of predictable grade will enable mine operators to send a product to mills of several thousand tons daily capacity. Ore shapes-up as worth more than $20 per ton. Already, many millions of tons of ore have been outlined and apparently reserves are sufficient to keep the proposed large mills going for decades. And the end is not yet in sight. This region in the Sudbury subdivision has been known for decades as having occasionally rich but sporadic occurrences of nickel, gold, pyrite, and other minerals. Because of the unpredictable mineralization for more than 80 miles along the contact line of a huge reversed "S" there was no record of successfully organized mining in the district-until the present one.

Jan 5, 1955

By John L. Edwards, Anthony T. Iannacchione

There has been a persistent need to forecast roof falls so that miner’s exposure to hazardous underground environments can be minimized. Several monitoring techniques have been developed and are used today with varying levels of acceptance in the mining industry. This paper examines the potential for monitoring microseismic emissions activity as a means of forecasting roof falls. The use of this activity to forecast roof falls has drawn only limited attention, resulting in a lack of published field performance data. This deficiency is being partially addressed by analyzing data obtained during longwall mining at Moonee Colliery in 1998. The Moonee data base contains a wealth of information concerning roof fall forecast parameters and the seismic alarm criteria used to develop these forecasts. Four seismic alarm criteria were developed and used by Moonee with varying degrees of success. Roof falls were forecasted 73% of the time with average forecast times of 54 minutes. Ninety percent of the predicted roof falls had a warning time, i.e., the time between warning and roof fall event, of greater than 1 minute. The fraction of forecasted roof falls decayed logarithmically as a function of warning time, until only 20% of events were predicted more than 100 minutes prior to roof falls. False alarms occurred in 50% of the warnings. Many of the false alarms were quickly followed by a cessation in mining which could have temporarily halted the on-going failure process. If mining had continued immediately after the false alarms, a roof fall may have occurred soon after. The microseismic activity collected from Moonee Colliery demonstrates that techniques to forecast roof rock instabilities in underground mines are possible.

By B. Trenary, D. D. McNaughton, C. D. Baer

High capacity off-highway haulage trucks equipped with electric wheel drives have been available for commercial applications since 1963 and, although still interesting to study, cannot be considered as a "new" type of equipment any longer. However, the electric wheel drive components which played a key role in the development of these trucks has indirectly led to another new trucking development-the gas turbine engine for off -highway vehicles. Although most of the production models of the electric-wheel haulage trucks are equipped with 700 hp engines (the largest production engine commonly available), the electric drive components of the motorized wheel were designed to transmit more than 700 hp. To utilize this added potential, 1000-hp class diesel engines are in the process of being developed, but progress has been much slower than expected. The delay has caused some engineering thoughts to concentrate on the adaptation of the 1000-hp gas turbine engines, originally designed for aircraft applications, for use in haulage trucks. The question in most minds centered around the ability of such an engine to withstand the tough usage expected of it in an open pit.

Jan 5, 1967

By D. Turnbull, R. E. Cech

THE supercooling behavior of pure liquid metal droplets has been described.' The solidification behavior of small droplets of Cu-Ni alloys as a function of composition is described herein. The Cu-Ni system is of interest for such an investigation because the components are miscible in all proportions in both the liquid and solid state and the phase diagram of the system, Fig. 1, is a type often encountered in metal systems. It was noted by Van Riemsdyk2 and others that the nature of the "blick" of gold droplets during assaying is not perceptibly affected by the content of the platinum group metals that are soluble in both liquid and solid gold. With the exception of these very qualitative observations there appear to have been no prior investigations of the supercooling of alloy droplets. A series of nine alloys varying in composition by 10 pct (nominal weight) steps was made using certified OFHC copper, 99.996 pct purity, obtained from the American Brass Co., and electrolytic nickel pellets, 99.92 pct purity, obtained from the International Nickel Co. The alloys were melted and cast in vacuo in a high frequency induction furnace. Segregation was minimized by chill casting into 1-in. diam steel molds. Each alloy rod was homogenized at a temperature 50°C lower than the solidus for 100 hr in dry hydrogen. Samples for solidification experiments and chemical analysis were machined from the same portion of each rod and at a depth of in. from the rod surface. A Car-boloy tool was used in taking turnings to minimize contamination of sample by the cutting tool. As a check, a number of samples for microscopic observation were chipped from the ingot with a fragment of pyrex glass. The resultant data in all cases agreed, within experimental error, with the data obtained from machined turnings. A number of small particles, 30 to 50 micron diam, of a Cu-Ni alloy were placed in a quartz vial 1/32 in. diam x % in. long. This was inserted into a platinum ribbon heater and mounted in a high temperature microscope stage. The general procedure followed in inserting samples into the stage and measuring the temperature of melting and solidification was the same as described in an earlier paper.' A chromel-alumel thermocouple was used to study alloys of 88.93 pct Cu, 80.62 pct Cu, and 72.27 pct Cu. A platinum-10 pct rhodium thermocouple was used for the remainder of the alloys. Procedure The assembled high temperature microscope stage was first evacuated and the sample given a 2 min in situ treatment at 900 °C in dry hydrogen to remove surface oxides which might otherwise catalyze crystal nucleation. After this treatment the atmosphere was changed to purified helium and melting and solidification were observed microscopically. It was not possible to determine the solidus with certainty. However, the liquidus temperature was measured very accurately since the surface of the particle changed in appearance from coarse and uneven to smooth, mirror-like within a few degrees. The visually determined liquidus temperature was checked by finding the highest temperature to which the particle could be heated such that it did not supercool upon lowering the temperature. This temperature which checked within experimental error with that found by observing surface change was assumed to be characteristic of the thermody-namic liquidus. In order to minimize the effect of selective evaporation of copper from the alloy, samples were changed frequently and the droplets were heated no more than 50 °C in excess of the liquidus temperature T,. When the latter conditions were fulfilled, T, values were reproducible. After melting, the temperature was decreased slowly until the particles solidified. The sudden release of heat of fusion on solidification caused the

Jan 1, 1952

By J, T C. McCuaig, J Hodgkison, T Fouet

Olympic Dam is the eighth largest Cu deposit and the largest U deposit in the world, with approximately 35 million tonnes of contained Cu and 1.2 million tonnes of U. The most recent resource estimate was for 2.95 billion tonnes of mineralised material with average grades of 1.2 per cent Cu, 0.4 kg/t U, 0.5 g/t Au, 2.6 g/t Ag as contained mineral resources. Olympic Dam is expected to produce >200 000 tonnes of Cu and 4200 tonnes of U3O8 from 9.8 million tonnes of ore in 2004, making it the 12th largest Cu producer in the world. One of the impediments to achieving targeted rates of production has been oversize material (>0.9 m) reporting to stope draw points. A major contributor to oversize material may be overbreak along pre-existing structural weaknesses from stope walls and backs during the production life of a stope. Underbreaking to structures can also have a detrimental effect on the performance of a stope. In an effort to understand the influence of structural geology on stope performance, WMC Resources and SRK Consulting partnered during 2003 to refine the current system of structural mapping, and to use historical data to produce a structural interpretation covering a large part of the mining area. The interpretation has been wireframed in DATAMINETM into a three-dimensional structural framework model. To date, there are more than 600 structures of >50 m strike length incorporated into the structural framework model, which covers a study area 1500 m + 600 m + 350 m. A back-analysis exercise to assess the influence of interpreted structures on overbreak and underbreak was completed for laser-surveyed stopes.

Jan 1, 2004

By O. Chemezov, Yu Zaikov, A. Apisarov, A. Isakov

"Silicon deposits containing 99,9 wt.% of main component were obtained by SiO2 electrolysis from chloride-fluoride melts. The operating temperature was varied from 973 up to 1073 K. The conditions for obtaining crystalline fibrous micro- or nanodeposits were determined. The deposits were investigated by ESM methodIntroductionThere are large reserves of natural quartz of high purity in Russia. Processing of this raw material by electrolysis in molten salts produces silicon containing 99.9 weight percent of basic substance.[1]This method is less energy-consuming in comparison to existing methods for producing high purity silicon from gas phase.Another advantage of the electrolytic method for producing silicon from its oxide in molten salts is the possibility of production of high-purity silicon under air atmosphere. It dramatically reduces costs of the electrolytic cell construction, and the operating costs at electrolysis.On our opinion, the main advantage of the electrolytic production from SiO2 in molten salts is a unique opportunity to obtain micro-and nanostructures of silicon deposits. In particular, it is possible to obtain fibrous structures of silicon. The electrolytic method allows smoothly adjusting the thickness and length of silicon micro- and nano-wires by varying the cathode current density and temperature of the process."

Jan 1, 2012