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Provide a rapid, reliable means of warning underground miners of a fire or other emergency. Approach An ultalow-frequency electromagnetic signaling system was designed, breadboarded, and tested at various under around mines. How It Works Current fire warning systems for underground mines, such as stench, audible alarms, and messengers, arc slow, unreliable, and seldom achieve total mine coverage. An ultralow-frequency electromagnetic fire warning alarm system with true through-the-earth signaling capabilities was developed to solve these problems. The system was originally designed for high-back room-and-pillar mines where stench systems are unusable due to the low velocity of mine air flow. However, the system has an application to all underground mines.

Jan 1, 1988

At the LKAB, Iron Ore Mine, Kiruna, Sweden a preliminary investigation into the reliability characteristics of a fleet of load-haul-dump machines has shown that the hydraulic system is one of the most critical parts. Therefore, hydraulic system was selected for study and analysis through condition monitoring devices so that failure can be controlled or at least the failure consequences can be minimized.The hydraulic system has two different problems; one is that the contamination level is too high and the other is high temperature during operation. At high temperature, seals and tubes are a problem, because they stiffen due to carbonization, which leads to increasing leakage. The pumps and restrictions were responsible for the main temperature increase.

Jan 1, 1991

The control of industrial grinding circuits in Australian concentrators has been practised for many years in one form or another. Some have established simple feedback loops in areas such as fine ore bin feeders (tonnage control), mill pump sump levels (flow control) and water additions (density control). There are also some sophisticated systems which infer circuit product size using complex measurements of mass flaws and water additions in the circuit and attempts are made to control those flaws to produce a constant circuit product size. The inferred size method in Australian concentrators has become firmly entrenched in the last ten years and control techniques involving the use of direct size measurements with reliable on-stream sizers have been Ignored.

Jan 1, 1983

Based upon specialised experience of rope mechanics spanning over 20 years, this paper reviews the processes of degradation and fatigue that are relevant to hoisting ropes in mines. The review is brought up to date with an account of the most recent work in this field, which identifies a torsional fatigue process and quantifies the impact of degradation upon the residual service life. A proper understanding of these processes is important in determining how different parameters of hoist design and operation interact to determine rope life. This knowledge is also important in informing decisions relating to rope discard based upon observed condition, as well is identifying the critical features that must be quantified reliably during inspection.

Jan 1, 2005

By Tomoya Kawasaki, Tatsuya Motomura, Yutaka Yasuda

Saganoseki Smelter, one of the largest copper producers in Japan, currently operates a single flash smelting furnace to produce 450,000 tons of new copper annually. The smelter used to employ two flash furnaces, and integrated the two into one in 1996. Since then, various improvements to its facilities and technologies have been made to increase productivity. To upgrade the operation efficiency, "stability" was considered a key issue, and the measures were taken to increase the operation and facility reliability. Currently, the furnace is running at a feed rate of 215 DMT/h, while the furnace utilization has been maintained at 97%. This paper outlines recent improvements that have made to increase furnace productivity and efficiency.

Jan 1, 2014

By John Bullock

Limestone and dolomite quarries were mapped to determine specific failure mechanisms for the various geologic and structural conditions. Algorithms for analyzing these mechanisms were incorporated into a software package together with ranges of physical properties such as joint shear strength, angle of internal friction, and cohesion for specified lithologic units. Reliability options using Monte Carlo sampling and sensitivity studies are included to evaluate alternative highwall designs. The package is designed to facilitate progressive stability evaluation of quarry highwalls as mining continues. This package includes an optimum design protocol that can be followed to avoid the potential of massive failure. The program was developed in conjunction with the quarry industry and is demonstrated using case studies.

Jan 1, 1993

By Baafi EY, Chatterjee PK

The quality of mine planning decisions ultimately depends on reliable estimates of the characteristics of the orebody. The quant- ifiable factors such as grades or thickness can be estimated from field data gathered from outcrops or exploratory drillholes. Since outcrop data is necessarily limited to the periphery of a deposit, extensive drilling generally is required. This paper outlines a method for selecting the number and location of additional exploratory boreholes using an iterative procedure based on a mathematical optimization concept called fixed point theory. The method is illustrated through its application to an exploratory drilling program for a coal mine where optimized locations gave a lower estimate of regional and block variances than a manual Choice.

Jan 1, 1986

An integrated mining equipment development organisation is typified by Deutsche Montsn Technologic of Essen, Germany. working on improvements in reliability, production and control in coal mines. Examples of recent mining advances are in mechanised roadheading, in different approaches to cutting technology, and in low height roof bolting.On the longwall face the mechanics of cutting are related to supplied energy as well as to dust make. In conveying both armoured face conveyors and conveyor belts are monitored. Roof support is not neglected and the continuous pumping of stowage slurries provides further options for longwall support. Surveying developments, particularly the gyro-theodolite, directional drilling. and shaft vehicle monitoring provide further examples of advances in control in coal mining activities.

Jan 1, 1991

By Bjørn Nilsen, Brian J. Ballou

The Tellnes open pit mine in Southwestern Norway has been operating since 1960. The maximum height of pit walls is currently about 150 meters with the current mine plan extending this distance to 400 meters with slope stability being a major controlling factor. As a result of unfavorable combinations of directions of major joints and faults, local stability problems have occurred several places in the pits walls. Stability problems have affected the reliability of main transport roads on several occasions. Most of such incidents have occurred during heavy rainstorms and during periods of repeated freezing/thawing. This paper reviews some of the stability problems and the measures taken to deal with such stability problems.

Jan 1, 2006

By M. Verri

The paper describes the design options available for the simultaneous production of liquid sulphur dioxide, via cryogenic condensation, and sulphuric acid in a sulphur-burning sulphuric acid plant. The impact of the operating conditions of the cryogenic condensation on plant capital and operating costs are discussed, with the main focus on the optimization of the most important economic and operative drivers of the non-ferrous mining industry, such as energy efficiency, reliability, and availability. A case history relevant to an integrated sulphurburning plant producing liquid sulphur dioxide and sulphuric acid, recently started up in the Democratic Republic of Congo, is described. Keywords sulphur burning, sulphuric acid, liquid SO2, cryogenic SO2 condensation, liquid sulphur dioxide, sulphur dioxide.

Aug 1, 2013

By Claudio Bisso, Javier Vargas, Charles Lozano

"This paper summarizes the activities performed to predict SAG milling throughput at Minera Esperanza. Having highly reliable geometallurgical models aided by the new computer tools and specific metallurgical testing to rely on has become a major issue in recent times due to their impact on the business. Minera Esperanza’s SAG throughput model was constructed by characterizing the ore feed and operational parameters of the plant. Producing a robust model required satisfying number of requirements for the parameters used for both the ore and the plant as follow: 1) geologic and geometallurgical characterization parameters; and 2) parameters of a plant running at the rated production under optimum operating conditions. Obtaining these parameters required increasing the quantity of samples and metallurgical testing through drilling campaigns, mapping the drill holes and putting samples through various comminution tests while sampling all operational flows at the plant to obtain the metallurgical information for the operational parameters. The information was entered on the JKSimMet software to enable a throughput model to be developed to output SAG mill throughput predictions that are very close to actual throughput figures, i.e., accurate within a range of 2% on a monthly basis."

Jan 1, 2014

By K. Prashant Sarswat

Isotopes are critical to a variety of applications including physical science analyses, biology, medicine, pharmaceuticals, and national security. In most cases isotopes must be relatively pure or highly enriched before they become useful. Current isotope separation technologies are relatively inefficient, capital and labor intensive, and often produced by a limited number of suppliers. In the category of isotopes, lithium is among other important candidates. Lithium is found naturally in two isotopes, 6Li which accounts for 7.5% of all lithium, and 7Li which makes up the balance of 92.5%. Each of these isotopes is important to the nuclear industry. 7Li is often used in the form of lithium hydroxide which is used to control pH in pressurized water reactors. The current supply of 7Li is based mostly outside of the United States, and its long-term supply is uncertain. Apart from supply issues, the use of mercury for 7Li separation is also a concern in commercial processing using the most common and efficient approach [1–3]. Hence, a reliable, environmentally friendly, and efficient technique is needed to produce 7Li. In this line of investigations, the authors used a two-compartment system and significant separation was achieved. In this piece of research, some preliminary results are presented including cell design and actual isotope ratio after enrichment. Applying an electro-potential across two electrodes can be used to drive electromigration of Li isotopes. The electromigration is in addition to normal diffusion. Note that 6Li diffuses faster and hence there will be a lowering of the 6Li concentration near the positively charged electrode and an enhancement in 6Li near the negative electrode during the separation process. Similarly, 7Li will be more prevalent near the positive electrode and less prevalent near the negative electrode during the initial separation stage [1].

By Carel Robinson

MECHANIZATION of coal mine, is radically changing the requirements for under-ground transportation. It has increased materially the need for reliability and belt conveyors are the most dependable means of moving coal away from the place where it is mined. Their record of freedom from delays is almost 100 per cent. Why then are- not belt conveyors in more general use. Part of the answer lies in the pour records made at some of the earlier installations, and in the fact that belts have so long been identified as a type of equipment suitable, in the main, only to thin seams. Another reason is lack of knowledge of the full potentialities of belt transportation.

Jan 1, 1941

By J. B. Ligon

Blast induced stress waves, propagating along the surface of a drift of an underground hardrock mine, were recorded and analyzed. Resistance strain gages, accelerometers and a velocity pickup were used in making the measurements. Although a full face blast was recorded, the stress waves were initiated by single borehole blasts for the majority of the project. A special instrument trailer was designed, constructed and utilized during the project. A reliable strain wave transducer was developed for measuring the stress waves propagating on the drift surface. A correlation study between strain and acceleration signals for P-waves was made which agreed well with theory. The use of stemming was found to reduce strain and acceleration magnitudes as predicted.

Jan 1, 2011

By C. Melvin Lepper

Microseismic energy is generated when stresses accumulated in rock formations are released in the form of fracturing. The acoustic emissions resulting from these rock fractures and movements are detectable as velocity signals in the earth near the energy source. A Bureau of Mines microseismic system that is capable of detecting the acoustic emissions from pit slope movements is described. The digital circuitry incorporated in the system allows a microprocessor program to immediately calculate and present the location coordinates for the seismic energy source in the mine pit wall. This monitoring system is compact, portable, reliable, and relatively inexpensive and rapidly provides accurate information to the mine operators about the stability of a pit slope.

Jan 1, 1982

By R. R. Boucher, O. J. C. Runnalls

A pronounced thermal effect has been observed on heating or cooling a1wninum-rich Al-U and Al-Pu alloys. From microscopic and X-ray diffractionstudies, the effectl has been attributed to trnsfor)nations in the inlemetallic phases UAl, and PuAl , involuing rearrangement or cluslering of vacancies The transformation obsrved in Al-20 wi oct U alloys occurred near the a Al-UAl4 eutectic tem-perature of 646°C making it difjicult to detect from heating curves. When cooling, howeoer, thermal mad X-ray analyses indicnted that the high-temperati~re phase labeled p UAL, precipitated initially during euitectic solidification. As solidification continued and after an induction period o-f 5 lo 20 tnin the nu-cleatiorz and growth of the low- twmperature phase, a UAl4 produced an euolution of energy which raised the observed alloy temperature by 1° to 2°C. in Al-Pu alloys the transformation occurred at 645°C, 5 deg below the eutectic solidification temperccture. The eslimated latent heat of transformation was 25 +5 cnl per g PuAl,. The high-tetnpevcl-ture forms of UAl, and PuAl, were easily 9-etccined by chill casting Al-U and Al-Pu alloys and on reheating the alloys the trcltzsforrnation to the a phase was sluggish even above 600°C. Separated single cryslals o-f UAl4, joy example, showed no evidence Of transformalion after heating for 16 hr at 620°C. The transformation rates increased yapidly enough with increasing temperature, however, that a a spontaneous liberation of energy lens observed on occasion when bealing cast Al-20 wt pet U to neal- the RECENT phase studies on A1-Pu alloys have indicated that earlier reported equilibrium diagrams should be modified to take account of several poly- morphic transformations in the intermetallic compound PuAl,.' During the course of the latter work an unexpected heat evolution was observed while cooling a solid alloy consisting of a mixture of a aluminum and PuA1,. The evolution occurred at 645°C, y below the a A1-Pu A1, eutectic solidification temperature. Subsequent thermal-analysis experiments with A1-U alloys showed that heat was evolved there also at a temperature nearly coincident with the a A1-UA1, eutectic solidification temperature of 646°. A search of the literature revealed that similar thermal effects had been observed before for both A1-U and A1-Pu but had never been fully explained.2,3 The purpose of the present paper is to describe thermal-analysis and X-ray diffraction experiments which have led to the conclusion that the thermal effects are due to transformations which involve the rearrangement of vacancies in the intermetallic compounds UA1, and PuA1,. EXPERIMENTAL PROCEDURE The A1-U alloys were prepared by heating super-pure aluminum (99.99 pct +) obtained from the Aluminum Co. of Canada in a graphite crucible surrounded by an induction coil. At 1000°C high-purity uranium metal produced by the Eldorado Mining and Refining Co., Ltd. was dropped into the liquid aluminum and was dissolved completely within 15 min. The impurities in the uranium were A1—4 ppm, Ca-4, C-70, Cr-3, Cu-6, Fe-30, Mg-2, Mn-10, Ni-25, Si-25, and Zn-2. The A1-Pu alloys were prepared by reacting plutonium dioxide with liquid aluminum under cryolite (3 NaF . AlF,) for 10 min at 1100°C in graphite crucibles exposed to the air. The plutonium was 99.8 pct pure, containing trace impurities of Ca, Cu, Fe, Pb, Si, and Zn. The liquid alloys were usually poured into water-cooled molds to provide castings of uniform composition from which samples could be cut for heat treatment and thermal-analysis experiments.

Jan 1, 1965

By C. W. Volek, J. E. Chappelear

The injection of a hot liquid into initially cool porous media, saturated with the same liquid and surrounded by two impermeable but heat conducting media (cap and base rock), has been studied both experimentally and theoretically. The temperature dependence of the viscosity was included in the theoretical model, but it was assumed that the specilic heats and densities of the various materials were independent of the temperature. Solutions to the theoretical model were approximated by numerical methods. Both theoretical and experimental results indicate that center-line temperatures are significantly higher than boundary temperatures. Comparison of experimental and theoretical results with a cold/hot viscosity ratio 01 19:1 were in reasonable agreement. Theoretical calculations show that the effect of the temperature dependence of viscosity was very significant at ratios of 100:l to 1000:1, which are typical of those that occur when injecting hot water to flood heavy oil reservoirs. INTRODUCTION We consider the problem of prediction of fluid flow and temperature distribution in an initially cold-fluid-filled reservoir on the injection of the same hot liquid by the use of mathematical and physical models. The results reported are for a two-dimensional rectangular section of the reservoir, as shown in Fig. 1. The injection and withdrawal faces are assumed to be equipotentials for fluid flow. The ultimate purpose of such models would be to predict hot-water injection performance. However, we note that in the work presented here, one of the most significant aspects of the problem — the instabilities resulting from two-phase, water and oil flow — is not included. We will not give a historical review, but refer instead to the paper of Spillette and Nielsen,1 which contains a rather complete bibliography and critical discussion. The physical problem is exactly the same as Spillette and Nielsen, except for certain simplifications in our assumptions. The mathematical details are somewhat different, and we will present the details of our method here. The mass flow equation, which is elliptic in character, is handled by successive overrelaxation. The heat flow equation, which is parabolic in character, is handled by a straightforward explicit approximation. Some difficulty arose in the over-all heat balance due to small errors in the solution of the mass flow equation, and we feel that a different formulation of the heat flow equation would be desirable for future work. In addition to the mathematical solutions for the temperature distributions in a porous medium due to the injection of hot liquids, experimental data are presented to check the validity of these solutions. A schematic diagram of the model is shown in Fig. 2. Certain qualitative physical conclusions were obtained from our numerical and experimental results. These are: 1. Assuming high (infinite) conductivity normal to the bedding plane in the reservoir is a poor approximation, and may lead to overestimates of the total heat losses (to cap and base rock) of as much as 50 percent. 2. More heat is retained in the reservoir (per unit of heat injected) for higher viscosity changes. 3. Any particular temperature isotherm moves more rapidly along the center line for higher viscosity changes. Consequently, the approximation of temperature independent viscosity is not suitable for obtaining quantitatively correct results. MATHEMATICAL MODEL Our mathematical model is that of a reservoir of thickness 2h. The problem is idealized from that of a linear hot-water drive, and we imagine that the input face is sufficiently far away from the injection wells that the stream lines enter it normally. Similarly the production wells are far enough from the outflow face that the flow lines leave it normally. The reservoir and surrounding cap and base rock

Jan 1, 1970

By C. Zangerl, H. Lechner

"Large scale rock slides in deeply incised Alpine valleys are common hazards that can endanger human life, settlement areas and critical infrastructure such as highways, railways and reservoirs (Bonzanigo et al., 2007). In order to perform reliable forecasts of the behaviour of rock slides influenced by large dam reservoirs the geometry, the kinematics, the deformation behaviour and the hydrogeological situation need to be understood profoundly. Based on generic rock slide models the influence of the rock slide geometry on the stability as well as the impact of the buoyancy forces and water load of the reservoir at the toe of the slope are the main focus of this study. Various assumptions of hydraulic conductivity, groundwater conditions of the rock slide and impoundment depth of the reservoir are analysed using limit equilibrium approaches.Generally, deep seated rock slides are characterised by deformation along one or multiple shear zones where most of the measured total slope displacement localizes. Many large rock slides, especially those observed in foliated, mica-rich crystalline rock masses (e.g. paragneisses, mica schists, phyllites), do not fail suddenly or reach high velocities. Instead, many of them move slowly and reach velocities of centimetres per year or even less. Some show episodic accelerations, sometimes reaching alarming levels, but then subside to non-critical levels again. However, there is a potential that deep-seated rock slides fail rapidly, develop into far-reaching run-out rock flows, and cause catastrophic events. Whereas the role of triggers in promoting phases of acceleration is often understood, the same cannot be said regarding the kinematics and dynamic processes by which the rock slide mass decelerates, re-stabilises or accelerates to a catastrophic degree once the trigger impetus has been removed. Thus key questions of the presented work concern the geotechnical, geometrical and hydrogeological conditions under which a slowly moving rock slide is triggered to accelerate to irreversible, maybe dangerous velocities. The development of the sliding zone is generally influenced by pre-existing discontinuities such as brittle fault zones, shear and tensile fractures, foliation and bedding planes. These geological structures determine the geometry of the sliding zone which can either be rotational or translational. During the gravitationally induced failure process the geometry of the rock slide undergoes a change.Several observed post-failure geometries in metamorphic rocks show a concave topography in the middle to upper part of the rock slide and a typical convex or bulge-like topography at the toe of the slope (Zangerl et al., 2012). Whereas the sliding zone of the upper part of such a rock slide mass is rather steep and planar, the inclination of the sliding zone at the toe can be close to zero and act against the driving forces (Alonso et al., 2010). A shear zone that meets alluvial deposits at the foot of the slope encounters a stabilizing impact on the mechanical behaviour. This buttressing effect of alluvial sediments has a remarkable influence on the slope stability."

Jan 1, 2015

By S. A. Shoop, J. J. K. Daemen

Site-specific blast vibration prediction can be more accurate than using a universal prediction equation. Vibrations from 37 blasts were monitored using three seismographs. Data analysis showed that square root, cube root, and site-specific scaling predicted ground motion with equal reliability. Imprecise prediction is caused by geologic and blast variability, particularly, inaccurate delay times. Vibrations at some mines were consistently lower or higher than vibrations predicted from US Bureau of Mines (USBM) equations. Vibration restrictions based on USBM studies could then be too conservative or too lenient. Predominant vibration frequencies were generally less than 50 Hz, but several blasts had significant energy up to 125 Hz. In some cases, energy was concentrated at frequencies corresponding to delay intervals.

Jan 3, 1985

By R. Mehta, M. Misra, X. Su

"The conventional methods to assess Acid Mine Drainage (AMD) potential of the waste rocks and tailings are based on wet chemistry and leachability tests. These methods are time consuming and expensive. There is a growing interest to develop alternate techniques to establish the reactivity of acid mine tailings and stability of treated waste forms. The Electrochemical Impedance Spectroscopy (EIS) is a reliable non-invasive technique which can be used for quick estimation of reactivity of the potential acid generating tailings. In this paper the utilization of the EIS technique for the estimation of reactivity of tailings is discussed. EIS can also be used to predict the long term stability of different stabilized waste forms.IntroductionMetal contaminated mine drainage is one of the most persistent environmental problems facing the mining and mineral processing industries today. Of all the mine drainage pollutants, acid mine drainage has become a substantial concern because of the potential long-term environmental implications and the accompanying liabilities. The main source of acid mine drainage is the tailings containing sulfide-ores which are generated during the ore processing. When these sulfide minerals, particularly pyrite and pyrrhotite, are exposed to oxygen and water they begin to oxidize. The initial chemical reactions produce acid and the acid dissolves heavy metals present in the tailings. Rainfall and snow-melt flush the toxic solutions from the waste sites into the downstream environment [1-2]. In addition to mining tailings, several Department of Energy (DOE) sites contain wastes which are contaminated with radionuclides and heavy metals."

Jan 1, 1999