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By William H. Pomroy, Kenneth E. Hjelmstad

An underground mine fire can seriously threaten the lives of all personnel in the mine. This fact makes fire emergency planning a high priority in the mining industry. A fire emergency plan includes a means of warning miners of the existence of a fire, and the need to evacuate or retreat to a place of refuge. The warning alarm must be fast and must reach all miners, regardless of their location or work activity. Means of fire warning are varied, and include such methods as stench, flashing lights, telephones, and word-of-mouth (messengers). Unfortunately, none of these methods are entirely satisfactory. Stench can be slow and seldom achieves total mine coverage, especially in high-back room-and-pillar mines with low ventilation velocity. Telephones are effective only where personnel are close enough to hear the phone ring. A novel fire warning alarm system has been developed by the U.S. Bureau of Mines which enables instantaneous warning of all underground personnel. The warning alarm is sent by an electromagnetic signal which penetrates through mine rock from a transmitter to small person-wearable receivers. Each miner's cap lamp battery could be equipped with a small receiver and when a fire or other emergency occurs the miner could be alerted to the danger by a blinking of the cap lamp. Testing of prototype equipment has demonstrated that the transmitted signal is capable of penetrating through over a mile of mine rock and activating the receiver. This paper describes the theoretical basis for through-the-rock ultra-low frequency electromagnetic transmission, design of the prototype transmitter and receiver, test results, and status of commercial development of systems utilizing this technology.

Jan 1, 1994

By Hugh K. Taylor

"With some justification, people have long complained about the indefinition of ore reserves. Perhaps they were led to expect too much; from former and easier definition practices in the once common underground mines with exposed and available assets, where the obsolete term 'ore in sight' was at least partly literal. But such mines have become rarer, and their underground development less affordable. For most projects, valuations and its definitions have thus been advanced from actual to prospective mines, leaving a very wide gulf between 'what is there' and 'what may happen to it'. This brings the double challenges of reduced geological and technical assurance and the protraction of economic uncertainties.This paper avoids the popular field of regional resources, being confined to what may possibly be mined within single or closely grouped deposits. For these, many estimates of tonnage and grade must be made, defined and declared long before assessment of feasibility; and the uncertainties of the latter make it an unsound base for defining the earlier quantities. Despite the best of intentions, implied or inferred promises may proveimpossible to honour.A simpler framework of definitions is suggested, to some extent reverting to an earlier dependence on supporting work rather than on opinions of economic assurance or future events that are more properly the functions of production and cash flow schedules."

Jan 1, 1994

By Lloyd Buckingham

"The operating cost of a gold mine employing granular activated carbon to recover gold can be greatly affected by the condition of in-circuit carbon and its attrition losses. To accurately identify and quantify carbon losses requires careful study. Carbon attrition in the mill can be attributed mainly to physical or mechanical breakage due to the transfer of carbon in the circuit and to carbon oxidation and thermal fracture occurring in the carbon reactivation kiln. Of the equipment involved in carbon transfer, the water powered eductors are the major cause of abrasion and should be replaced with pumps or alternate methods that can serve the purpose. This paper also reviews the impact of carbon stripping and washing on overall operations.IntroductionHolt-McDermott Mine operates a 1360 tonnes per day Carbon-in-Leach (CIL) mill to recover gold. The relatively high carbon consumption and high remaining gold values on carbon after stripping were viewed as a challenging project for research. Extensive metallurgical testwork was initiated to reduce these values. Figure 1 below indicates the carbon flowchart prior to any significant changes in the carbon handling procedures.Carbon consumption after commissioning which was as high as 10""/o of carbon eluted, has been brought down to less than 5%. Changes that brought about this 50% reduction in carbon consumption are:1 ) Improvements in kiln operation2) Elimination or replacement of eductors3) Reduction in tonnes of carbon eluted"

Jan 1, 1994

By R. Spring

"Soft-sensors are a computer software alternative to inadequate hardware instrumentation. Filters are averaging methods that reduce the noise in any sensor's signal. This paper introduces these topics and places them in a mineral processing context using then-product formula.Soft SensorsAs their name implies, ""soft-sensors"" are computer programs that estimate values for process variables (Tham, 1991). This approach is useful when the appropriate hardware sensor does not exist, is deficient, supplies only infrequent values, etc. For example, in mineral concentrators the traditional magnetic flowmeter/ nuclear density gauge instrumentation for measuring slurry flows costs $5,000 or more per flow and requires frequent maintenance. However, metal assays are commonly available from online X-ray fluorescence analyzers and application of the n-product formula (Taggart, 1945) to these assays conveniently provides software estimates of the flowrates (albeit only when the circuit is in steady-state).Soft-sensors are used by inferential controllers that base their control actions on the process values ""inferred"" by the soft-sensor. Such was the case at Brenda Mines where the rod mill feed tonnage controller used an inferred value of the cyclone overflow particle size (Bradburn, 1976). It was also the case at Brunswick Mining where reagent controllers adjusted reagent addition rates throughout the plant according to the various ore flowrates inferred by an expert system (Spring, 1991). A unique feature of the expert system soft-sensor was its dynamic flow models which compensated for residence times, material transport lags, etc. Thus the soft-sensor values were valid under both steady-state and nonsteady- state conditions."

Jan 1, 1992

By J. Elbrond

"This paper describes qualitatively the progressive are losses and rock dilution in a mining project from the geological modelling to and including the concentration. A simple theoretical model of the net present value of a deposit, assuming a log-normal grade frequency function, is used to find the pair of decisions on rate of production and cut-off grade, which maximizes the net present value. Various degrees of ore losses and rock dilution are then applied on this optimum, and the resulting decreasing net present values are calculated, as well as the increasing cost of metal and the increasing metal losses as a function of are losses and rock dilution.IntroductionDue to a variety of uncertainties, to inevitable lack of precision in deposit estimation and in mine planning, and due to production constraints, ore losses and rock dilution occur throughout the many phases of a mining project. The phases range from the geological definition of the orebody, over the cut-off grade optimization and decision, over the design of the mining method and the actual mining to the ore dressing, where the final loss of valuable ore into the tailings occurs. Quantification of ore losses and rock dilution are mostly difficult if not simply impossible to obtain. At the end-phase an estimate of the total dilution may be obtained with some degree of precision by observations of the amounts and analysis of concentrate and tailings. It is much more difficult to estimate the total ore losses because the uncertainty of the geological modelling in the initial phase and in the mining phase is very difficult to quantify, despite the use of geostatistics for grade estimation.Many attempts at quantification of ore losses and rock dilution have been made and some examples are shown in Table I. Although they differ widely from each other, it is obvious from these figures that ore losses and rock dilution are significant and have considerable effects on the economical results of a mining operation. Life length, net present value, cost of producing metal and the loss of metal are all affected."

Jan 1, 1994

By Janne Karonen, Stephen Hughes, Mikael Jåfs, Jan Stål, Hannu Johto

End-of-life electrical and electronic scrap material attracts attention as a good opportunity for new value creation through efficient metal and energy recovery of such materials. On the other hand, the treatment of such wastes becomes important to avoid problems for society and environment. Treatment of such secondary raw materials faces multiple challenges due to their increasing complexity and evolving nature. Processing of these complex scrap materials together with recovery of a wide range of valuable metals with a combination of pyrometallurgy and hydrometallurgy using Outotec technology is discussed in this paper. One key consideration is environmental performance which needs attention when processing such complex secondary E-waste materials. Outotec has successful experience with commercial projects in the countries at the forefront of environmental and operational standards. INTRODUCTION Increasing attention has been drawn to the responsible processing of end of life Waste Electrical and Electronic Equipment (WEEE) as part of metals recycling, especially copper. It has been estimated that the amount of WEEE globally in 2016 was around the level of 46 Mtpa (Balde et al., 2017), representing a major disposal challenge but at the same time huge opportunity for resource recovery. The potential for increasing the recovery is high, because the official recycling rate of WEEE is in 2016 only 20% (Balde et al., 2017) and at the same time the estimated increase of the WEEE amount is between 3 and 5% per annum in the EU (Eurostat, 2019).

Jan 1, 2019

By Nicolas Gatelier, Sophie Laurent, Thierry You

Hard-rock caverns for hydrocarbon storage are a very particular type of underground facility controlled not only by local administrative and regulatory constraints that can be very specific, but also by the possible risks of geotechnical or geomechanical failure. Each such facility throughout the world is a prototype that needs to be adapted to very different site conditions. The straight forward application of design methodologies from relatively similar fields (mines, tunnels) can be very useful, but risks holding back the scientific and technical improvements needed by an engineering industry in full development. Here we look at various case histories and at problems that have been raised where recent attempts at standardization would appear to have been ill adapted, and where storage designers, through experience and judgment, may still provide innovative engineering solutions.

Jan 1, 2015

The Curtin University Gold Technology Group has been involved in surveying, modelling and optimisation of batch centrifugal concentrator type gravity circuits and CIP/CIL circuits for nearly two decades. The most commonly asked question regarding gravity recovery is, “What is the benefit of a gravity circuit”, which can be hard, if not impossible, to quantify. With the help of the AMIRA P420 Project’s Integrated Liberation Leach Model (ILLM) it is now possible to evaluate the effect of gravity recovery on total gold recovery when changes are made to the grind size, gravity and/or leach/adsorption circuits. This paper demonstrates how the ILLM can be used to determine the net benefit of introducing or modifying a gravity circuit and assess the effect of operating conditions (grind size, coarse gold size distribution, leach residence time, carbon activity, etc.) on plant performance.

Jan 1, 2017

By J. Pontt

Gearless mill drives (GMD) offer high performance for torque and speed control for grinding mills and have been applied successfully in modern concentrators for wet grinding with mill diameters from 34 to 40-feet. It is considered a mature technology. However, recently, some large GMD?s have presented unexpected failures in stator and rotor subsystems. The phenomena involved in such failures has shown a complex nature and surprised users and manufacturers. The manifestation of such failures has been observed as mechanical damages to certain components of ring motors. This paper presents a discussion on the electromagnetic forces that can generate stresses in the electrical ring motor that can produce failures and outages. Guidelines for further research and contributions to improved reliability of GMD?s are proposed.

Jan 1, 2012

By Victor Rudenno

"Previous methods have employed statistical analysis to model future mineral resources. The method presented in this paper uses Zipj's Law to determine the size and grade of tin deposits still to be discovered. The law is applied independently to both known deposit tonnage and grades. A probability distribution for both 'tonnage and grade is computed/or those deposits still to be located and then, by applying a correlation between tonnage and grade, a distribution of the probability of metal content discovery is obtained.By considering an economic cut-off in metal contained in a deposit, the probability of economic success for the next tin discovery is computed, both for a world discovery and for the special case of Tasmania, Australia. The results indicate a probability of 11-37% on a world-wide basis and 18% chance of economic success in Tasmania.IntroductionIn the past , most attempts to determine the probability of success in finding an economic mineral deposit have relied on the accumulation of statistical data. These data are then used to predict a suitable frequency distribution to assess the probability of finding a deposit of a given size and grade (Singer,1975).The method not only relies on one having sufficient data, but also on the assumption that the data are not biased and that the distribution (usually log-normal) is a correct one. The method presented in this paper, to analyze tin deposits, uses Zipf's Law, which has been recently applied to oil, uranium, lead-zinc and gold deposits by Folinsbee (1977) and to Western Australian gold deposits by Rowlands and Sampey (1977). Tapp and Koniuszko (1978) have applied Zipf's Law to mineral distribution patterns in the Northern Australian orogenic provinces, which has enabled them to make predictions with a relatively small data source."

Jan 1, 1981

By Jeff Smith

Agenda About NORTHPARKES The NEED The INITIATIVE The SEARCH The PRODUCTS The SOLUTION The RESULTS The Northparkes copper-gold mine in Central Western NSW commenced operations in 1994. Copper concentrate is produced and shipped to smelters in Japan, China & India under long term contracts with spot sales to other Asian countries.

May 1, 2006

"The successful commissioning and ramp up of the Albion Process™ at the GPM Gold Project relied on the successful scaling up of the process from batch and continuous pilot plant campaigns (Voigt et al., 2015). Critical information about reaction kinetics and residence time, grind size and pulp density were determined at the laboratory scale and successfully applied to the commercial scale. A limitation of small scale testwork, is that some parameters cannot be measured reliably and scaling up is a function of the physical size of the equipment which isn’t possible to test with laboratory scale equipment. Oxygen mass transfer rate is one such parameter since this is a complex interaction of many factors including slurry temperature, solution and slurry chemistry, slurry viscosity, agitator type, dimensions and power, oxygen bubble residence time, oxygen purity, tank geometry and oxygen injection technique. Oxygen generation represents an important operating cost for the Albion Process™. Pivotal to the Albion Process™ operating economically at atmospheric pressure is the capability to efficiently transfer oxygen while utilising as much oxygen injected to the process as possible. To respond to this Glencore Technology developed the HyperSpargeTM supersonic gas injector. This paper compares the HyperSparge™ against other sparging techniques to quantify the benefits of oxygen injection via a supersonic gas jet on scale up of the oxygen mass transfer system. The paper then examines plant survey data from the GPM Gold Project to demonstrate the very high oxygen utilisation that can be achieved with a correctly designed oxygen mass transfer system.INTRODUCTION One of the main challenges in chemical reactor design is the scale-up of processes from the laboratory to industrial scale. Processes which cannot be faithfully simulated with an experiment at the laboratory scale face challenges due to the physical dimensions and complexity of full scale operation. One example of this is the design of oxygen mass transfer systems in atmospheric oxidative leaching circuits such as the Albion Process™. A number of constraints associated with the use of laboratory scale equipment to design full scale circuits are involved in gas mass transfer processes in agitated slurries such as the Albion Process. Chiefly, typical laboratory and pilot size equipment lacks the required volume to provide useful design data without relying on empirical correlations: the specific agitator power input is artificially high, the bubble residence time in the vessel is artificially low, the oxygen partial pressure at the base of the vessel is artificially low and the oxygen delivery method may differ significantly to the industrial process. Further, the dynamic nature of the process introduces additional impacts on gas mass transfer, including the presence of solids, recycle streams and minor elements, plus the variances within the reality of a process plant such as disruptions or variance of feed quality."

Jan 1, 2017

By G. Chahal, L. C. So, S. Faucher, S. Mostaghel, S. -Y. Oh, S. K. Lee

Slag dumping and water granulation are the most commonly used slag treatment methods in the metallurgical industries. In both processes, water is present (by desire for cooling and dispersion or as a result of rain accumulation) and thus equipment and operations are designed to minimize and mitigate the risk of steam explosions resulting from the inappropriate contact of slag with water. Slag handling practices have, therefore, never been inherently safe; even good design, operation, and maintenance are not sufficient to prevent explosions or other related injuries from occurring. For slag handling to become inherently safe, our industry must eliminate the potential contact of water with molten slag. This is today feasible with the advent of dry granulation technologies, a review of which is presented, and it thus falls to us, in the metallurgical sector, to lead the way in their final stages of development and adoption. Furthermore, while slag dumping and water granulation offer some metallurgists the means of valorizing their slag as a by-product, for most, this is not the case. The energy in slag is lost through dumping and water granulation processes, and where slag is sold as a by-product, it is for its chemical content only. Here, dry granulation processes also offer advantages including the production of by-products which hold value in both their chemical content and physical properties and heat recovery. Dry granulation, therefore, augments the methods by which slag may be valorized over traditional processing methods.

Jan 1, 2015

By L. Tang

A seismic monitoring system was installed in 2005 at Dongguashan Copper Mine, the deepest metal mine in China. Based on the seismic events monitored in situ, the possibility of rockburst prediction and prevention is investigated in this paper. The characteristics of space-timeintensity of mining-induced seismicity and the seismic response to mining are studied in detail using the seismic data in Dongguashan Mine. A conceptual model and a criterion of assessment of hazard seismic nucleation are proposed for Dongguashan Mine. In this model, the mine seismic stiffness method is adopted for rockburst prediction within the framework of the unstable failure theory. To analyze rock failure cases in Donggauashan Mine, the rate of the ratio of stiffness of rock in nucleation area to its surrounding area is proposed as a criterion for rockburst prediction.

May 1, 2009

By D. W. Li

Due to the ultrasonic testing and mechanical wind speed sensor have high requirement for the environmental of the coal mine, the charge induction wind speed detection method based on wavelet analysis is proposed. The same wavelet disturbance detection method is used at a fixed distance to obtain an induction signal to obtain a pass time, and then calculate the magnitude and speed of the wind. Simulation and verification experiments show that the method has application across a wide range of test speeds (up to 60 m/s). The metal probe causes little pipeline flow field interference. The method is particularly well-suited to dusty environment, and does not cause dust deposition through long-term operation. It can be widely used in coal mines for point wind speed continuous online testing.

Aug 1, 2013

By D. R. Schmitt, N. Ong, R. S. Kofman

Shales and mudstones comprise about 75% of all the sedimentary rocks. In, particular, organic rich shales are considered as a petroleum source rock and more recently with the advent of hydraulic fracturing technology to be a reservoir in their own right. In this sense, the aforesaid motivates our work with laboratory measurements of elastic properties of these geologic materials, which are known to be anisotropic. As such, assuming Vertical Transverse Isotropy (VTI) symmetry, the dynamic and static moduli of a series of cores from various geological formations in Alberta, Canada are simultaneously investigated as a function of confining pressure using the ultrasonic pulse transmission method and strain gages. Dynamic moduli were obtained from ultrasonic P- and S-wave velocities measured on a prism cut with faces perpendicular, parallel and oblique to the assumed vertical axis of symmetry. Static moduli were calculated from strain-stress curves obtained along the directions perpendicular and parallel to the assumed axis of symmetry as well. Velocity measurements show that samples are highly anisotropic, but that the pressure-dependent behaviour of the wave speeds differs. VP(90°) and VSH(90°) both with layer parallel propagation and polarizations change little with pressure while VP(0°) and VS(0°) (both with layer perpendicular propagation) display significant nonlinear responses particularly at pressures < 25 MPa. These characters transfer to the derived full set of elastic constants. In order to effect a proper comparison of the dynamic and static moduli, we convert the dynamic elastic constanst to linear compressibilities pependicular (Kdyn1) and parallel (Kdyn3) which are directly comparable to the static tangent compressibiities obtained by differentiation of the observed strains. Both sets highlight the anisotorpic nature of the material but most interestingly Kdyn1 _ Ksta1 but Kdyn3 > Ksta3 by nearly 40% for one of the samples. The other samples measured respond similarly suggesting that conceptually the structure of such materials could be considered to be constructed of alternating stiff or compliant layers. This finding has implications in the response of the formation to stress particularly during hydraulic fracturing and the interpreation of acoustic logs in providing appropriate measures of elastic properties for engineering purposes.

Jan 1, 2015

By B. E. Jones

"The area of uranium deposition is situated within the Churchill Province on the western edge of the Wollaston Iithostructural domain where it underlies the eastern edge of the Helikian Athabasca Formation. The Collins Bay deposit is 6 miles north-northeast of the Rabbit Lake mine. Two principal zones of uranium mineralization are described.The ""A"" zone is a partly eroded, high-grade pod of metal oxide and arsenides sheathed by clay-like minerals. It trends north-northeast and lies under 25 to 40feet of water. Uranium mineralization is localized at or adjacent to the unconformity between the Athabasca Formation and the basement rocks. The basement comprises a granitoid Archean terrain overlain by paragneisses of the Aphebian Wollaston Group. ""A "" zone ore contains phyllosilicates, quartz, pitchblende, rammelsbergite, pararammelsbergite, carbonaceous material, galena, gersdorffite, niccolite, carbonate and a trace of sphalerite.The ""B "" zone lies 6,000 ft south of the ""A "", and subcrops under till cover. It is a partly eroded zone composed of metal oxide and arsenides which occur within variably altered Athabasca Formation. Minerals recognized are phyllosilicates, pitchblende, niccotite, gersdorffite, millerite, carbonaceous material, pyrrhotite, skutterudite and a trace of galena. The Athabasca Formation varies from 90 to 160ft thick. Granitoid gneisses of probable Archean age and paragneisses of the Wollaston Group underlie the deposit. An easterly dipping thrust fault transects its length.The deposit is typical of the ""unconformity-type"" uraniumnickel deposits of the Athabasca Basin. Observed features fit well with the ""diagenetic-hydrothermal"" model for such deposits, as envisioned by Hoeve and Sibbald (/978)."

Jan 1, 1980

By J. T. Birkholzer, M. Rutenberg, K. -H. Lux, R. Wolters, J. Rutqvist, L. Blanco Martin

In this paper, we present numerical results corresponding to the Thermal Simulation for Drift Emplacement (TSDE) test, conducted in the Asse salt mine (Germany) between 1990 and 1999 to simulate reference repository conditions for spent nuclear fuel in rock salt. This test is of significant relevance for nuclear waste disposal in salt because extensive research and measurement programs were set up for the experiment. In our numerical study, we use two sequential simulators, TOUGH-FLAC and FLAC-TOUGH, and we investigate two-way coupled processes, focusing on thermo-mechanical analyses due to the main effect of heating. The two simulators used have recently been updated and are able to deal with large strains and creep processes. Moreover, specific constitutive relationships and coupling functions for rock salt and crushed salt under repository conditions are available. Within the framework of a benchmark exercise between Lawrence Berkeley National Laboratory and Clausthal University of Technology, the same scenario has been modeled in three dimensions using the two simulators mentioned. The main objective of the current, first stage of the benchmark is to evaluate the capabilities of these two simulators to predict relevant processes under repository conditions for high-level nuclear waste in saliniferous media. The comparison of the numerical predictions between them is very satisfactory, leading to a successful code-to-code verification. The comparison between measurements and numerical results shows that the most important processes are captured by the codes and constitutive models used. However, some differences exist between measurements and numerical results. These differences will be addressed in the next stage of the benchmark exercise, in which a parameter fitting effort will be undertaken. Overall, from the results obtained it can be concluded that TOUGH-FLAC and FLAC-TOUGH have the necessary capabilities to reproduce relevant processes under repository conditions for high-level nuclear waste in saliniferous formations.

Jan 1, 2015

By M. O. Pekguleryuz, D. S. Aydin

The high temperature oxidation and ignition resistance of Mg-(0-6) wt% Nd alloys have been investigated via isothermal and continuous heating experiments conducted in air atmosphere. Alloy composition is observed to be effective in low levels (~ 0.5 %) in the ignition temperature (Ti) of the alloys; the Ti of pure Mg increased from 630 °C to 770 °C with 0.5 wt% Nd addition. However, no noteworthy improvement was achieved with further additions up to 6 wt% Nd. The initial microstructure was observed to determine the oxide structure on the surface due to the differing oxidation behavior of the phases (a-Mg + Mg12Nd intermetallics). It has been found that the formation of a Nd-depleted region at the subsurface due to extensive Nd oxidation at the oxide/intermetallic interface lowers the protective ability of the oxide scale.

Jan 1, 2015

By A Smirnov

The problem of thin and very thin coal seam extraction is examined in a long perspective of Ukraine?s fuel and energy industry development. The technical and economic benefits of the coal seam selective mining technique are described, including beneficial environmental impact.

Aug 1, 2013