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By John R. McWilliams

This is one of a series of reports being published by the Bureau of Mines on mining methods and costs at various mines throughout the United States. Including the Holden mine in this series is particularly appropriate at this time. The mine was operated on a low-cost, large-scale production basis to compensate for low-grade ore. Even with the best conditions and the most efficient methods, the margin of profit was small. Under the present situation of rising costs and lowering metal prices, the profit margin vanished. On June 28, 1957, the mine operations ceased; therefore, this report can review the entire life span of the mine.

Jan 1, 1958

By K. Schwerdtfeger

Data are presented on the effect of iron oxide on the electrical conductivity of CaO-SiO2-FeO-Fe2O3melts, and on limiting current and impedance in direct current or alternating current charge transfer at iron electrodes. The strong influence of iron oxide content can be utilized for in situ determination of total iron oxide content and Fe3+/Fe2+ratio. The possible probe designs are presented and the principles and procedures of the measurements are explained. Keywords: in situ probe for iron oxide determination in steelmaking slags, electrical conductivity of CaO-SiO2-FeO-Fe2O3slags, direct current over voltage and alternating current impedance at iron/slag electrodes.

Jan 1, 2004

By K. Najim, D. Hodouin

"The raw ores which are processed in mineral processing plants exhibit very strong variations of their physical and chemical properties. As a consequence, the performances of the comminution and separation processes vary greatly from time to time. Model-based control strategies improve the performance of the plant; however, they require some form of adaptation to cope with the variations of the are properties.This paper deals with the use of adaptive techniques for the control of mineral processes. It begins with a survey on adaptive control algorithms including parameters estimation aspects. Then several examples dealing with crushing, rod, ball, autogenous and semi-autogenous grinding, flotation , drying and calcination processes are reviewed.IntroductionThe operation of the various processes of mineral processing plants (crushing, grinding, flotation, dewatering, etc.) is generally controlled using empirically tuned regulators of constant structure, such as PID controllers. To improve the operation performance, mineral processors try to implement specifically designed controllers, i.e. controllers based on plant dynamic models. Most of the time, these techniques improve the control of the mineral processing installations. However, modelling is a complex procedure because of the problems of measurement and data management, specific to this industry, and because of the variations of the model parameters. In this context model-based control strategies do not always bring the expected improvements or are sometimes discarded and replaced by more conventional techniques .The sources of variation of the dynamic behaviour of mineral processing systems can be classified into three categories: (I) the inherent changes of the raw ore properties (composition, grindability, mineralogical texture, etc.); (2) the process tuning modifications (grinding media loads, number of hydrocyclones, slurry level in flotation cells, agitation speeds, etc.); (3) the feedrate variation of the ore, water, chemical reagents, etc. All these factors change the fundamental properties of the process dynamics such as the grinding or flotation rates and the residence time in the equipment. The simplified linear models which are used to describe the process dynamics are not able to track the complex behaviour of the mineral processing systems when the amplitude of the sources of variation are too large. The mismatch between the model and the plant behaviour is then frequently a cause of model-based controller failures."

Jan 1, 1992

By J. A. López-Molina, S. García, V. Castellanos-Pedroza

"Groundwater inflow into underground constructions may cause hazardous working conditions and environmental problems. It is essential to localize and characterize potential flow paths and to estimate the amount of water leakages, so that appropriate sealing works can be performed. Estimating the amount of water ingress is a multi-phase process starting from qualitative and quantitative examination of rock mass. Due to association of uncertainty, vagueness and incompleteness with the monitored data set, particularly resulted from the in situ tests, accounting relevant approaches such Fuzzy Logic and Recurrent Neural Networks, are proposed in this research for learning acquisition, extraction of rules and prediction of behaviors. The computational set of artificial tools permits using the complex information entities or information granules (rock types, geologic structures, hydro-fracture potential) for data abstraction and derivation of knowledge from records (numerical or linguistic format). This is more a theoretical perspective than a set of methods or principles. As a theoretical perspective, this proposal encourages an approach to data that recognizes and exploits the information present in indexes at various levels of resolution or scales. In this sense, it encompasses the methods which provide flexibility and adaptability in the resolution at which knowledge or information is extracted and represented. The product of merging these tools is a 3D artificial-mapping of rock classification (Qi-system), geological conditions and Lugeon units that permits, as far as possible, to understand more and better the flow behavior."

Jan 1, 2015

By R R. Large

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The formation of orogenic gold deposits is commonly a two-stage process. The first stage involves preconcentration of gold in a suitable source rock, such as carbonaceous black shales, felsic volcaniclastics or komatiitic volcanics. The second stage involves the release of gold (commonly with arsenic and/or tellurium) from the source rocks during metamorphism or magmatic intrusive events, accompanied by the replacement of source rock pyrite by pyrrhotite. Recent research suggests that synsedimentary gold trapped in the structure of diagenetic arsenian pyrite in reduced carbonaceous facies of continental margin sedimentary basins is an ideal source of gold for many orogenic and Carlin-style gold deposits. The conversion of diagenetic arsenian pyrite to pyrrhotite during basin closure and greenschist facies metamorphism is the key process releasing gold and arsenic to the metamorphic fluid, with metal deposition in structural trap sites to form the deposits.CITATION:Large, R R, 2015. Orogenic gold deposits – a two-stage process of gold enrichment, in Proceedings PACRIM 2015 Congress, pp 335–340 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

The safety analysis of shaft-sinking operations included a review of accident reports from coal and metal-nonmetallic mine shaft-sinking projects in the United States, a review of foreign and domestic shaft laws, and discussions with shaft contractors and Federal mine inspectors. Accident data were studied to identify the most common and the most severe types of shaft accidents and to determine their immediate and contributing causes. Additional factors such as worker training and experience, equipment and sinking procedures, regulations and enforcement practices were also investigated to determine their impact on shaft safety. The results of the study are summarized in recommendations for improved training of shaft miners and clarification of Federal shaft-sinking regulations. A guide to assist mine inspectors in examining shaft-sinking projects is also included.

Jan 1, 1977

By Jacques Moraille

The public is asking for more aesthetic designs if they can be proven cost-effective at providing an appealing element to new dams. Lake Lenexa was designed and built around the idea of providing for basic dam functions such as flood control, enhanced water quality, recreation but also to provide an inviting community focal point for the residents to visit and enjoy; truly interact with the dam. The architecturally unique dam and ?one of a kind? spillway were designed to symbolize the water cycle as water moves from nature into the urban environment and the back to nature. A pedestrian bridge that spans the spillway offers visitors a good view of cascading pools and a fountain. The original Lake Lenexa dam layout incorporated relatively high, cast-in-place concrete retaining walls to form the spillway structure. The Black & Veatch project team performed a Value Engineering (VE) study to determine cost-effective means for implementing architectural features within the spillway, which resulted in innovative uses of construction materials not typically used in dam and reservoir construction. The VE study concluded that mechanically stabilized earth (MSE) retaining walls that are normally used for transportation projects would be a cost-effective alternative to the originally planned cast-in-place wall systems for the main spillway and stilling basins. The Black & Veatch study added value by mixing cement-kiln dust (CKD) with on-site clay soils to produce a stabilized material for use under the spillway. The CKD stabilized material properties include low compressibility, high strength and low permeability, which reduced seepage and uplift pressures under the spillway slabs. The cost savings provided by the VE alternatives reduced total costs and enabled architectural elements. The award winning dam design also used drilled caissons, expanded polystyrene (EPS) block forms, customized steel forms and external concrete vibrators to build the pedestrian bridge and upper spillway structures.

Jan 1, 2009

By Scott Ellenbecker

The formation in Newmont Mining?s Phoenix Mine near Battle Mountain, NV contains high levels of abrasive quartzite as well as gold, copper and silver. Newmont started mining operations at Phoenix (formerly Battle Mountain Gold) three years ago and the planners knew they were working with a challenging geological formation. But as it turned out, it was more challenging than anticipated. Mine manager Mark Evatz said, ?Anything that touches Phoenix rock wears fast. The rock fights back here.? To contend with the hard conditions, Newmont uses Atlas Copco?s Pit Viper 271 (PV-271) blasthole drill. Because of the hardness of the rock, drilling at Phoenix requires hammer drilling and the mine uses Atlas Copco TD65 hammers with 171 mm (6.75 in.) bits. The mine?s PV-271?s are outfitted with a single 41 m3/min (1450 cfm), 2.4 MPa (350 psi), oil-flooded air compressor. Phoenix has six Atlas Copco PV-271 drill rigs plus an Atlas Copco DML and a DM45 midrange blasthole rig. The mine?s goal is to keep 3.6 Mt (4 million st) of muck in inventory to stay ahead of the shovels and support needed operational flexibility (ore control related). Drilling efficiency has been a continuous point of improvement since operations began at the mine. The single-pass depth capability of 16.5 m (55 ft) on the PV-271 helped with that. Originally, the plans called for 6-m (20-ft) bench heights, supported by 7-m (23-ft) drill depths, and time spent moving from hole to hole was eating up productivity. Drilling on that plan resulted in drilling an average of 14 m/h (47 ft/hour). When depths were changed to 13-m (44-ft) drill depth, supporting blasting of 12-m (40-ft) benches, they were able to use the single pass capacity of the PV-271. Performance increased to more than 18 m/h (60-ft/hour) an hour. Although the drill depth change largely supported the improvement, other aspects of continuous improvement associated with improved knowledge of the Pit Viper drills helped as well.

Jan 1, 2009

By Roussos Dimitrakopoulos

Conventional approaches to estimating reserves and optimizing mine planning and production forecasting result in single, often biased forecasts. This is largely due to the non-linear propagation of errors in understanding orebody attributes from a limited finite number of drilling data, throughout the chain of mine planning and mining. A new mine planning paradign is considered herein to include two interacting and potentially fusing elements: stochastic simulation and stochastic optimization. These two elements provide an expanded mathematical framework that allows the modelling of orebody uncertainty and its direct integration to mine design, production planning and valuation of mining projects and operations. This stochastic framework has shown to increase the value of production schedules in the order of 25%. In addition, case studies show that stochastic optimal pit limits are about 15% larger in terms of total tonnage, compared to the conventional (deterministic) optimal pit limits. This difference extends life of mine and adds approximately 10% of net present value (NPV) to the NPV reported above from stochastic production scheduling within the conventionally optimal pit limits. Furthermore, results suggest a potential new contribution to the sustainable utilization of natural resources.

Oct 1, 2009

By Linneas Laage, Thomas Weber, William Pomroy

"Underground mine fires can significantly influence mine ventilation airstreams, in some cases throttling or even reversing airflows. As a result, the performance of a metal and nonmetal mine stench fire warning system, which depends on the ventilation to carry the vital warning signal, under fire conditions is different from performance under nonfire conditions. The safety of underground miners can be jeopardized if the warning signal is delayed. This Bureau of Mines report describes research to investigate fire and stench warning system interactions. A computer model is presented that permits quantitative analysis of stench warning signal delays as a function of fire location and intensity. The results of a case study involving computer simulations of stench distribution in a hypothetical mine network subject to various fire exposures are also discussed. This case study illustrates a technique for identifying the areas within a mine that are subject to unacceptable warning signal delays, thereby enabling preemptive action by mine personnel, such as redeployment of stench injectors. INTRODUCTIONFires are an ever-present threat to the safety of underground miners. Since the smoke and toxic gas produced by a mine fire can be spread rapidly by the mine's ventilation system, mine evacuation must be accomplished as quickly as possible in the event of fire. In metal and nonmetal mines, the most common means of passing the fire warning signal to each miner is the stench system. The typical stench system utilizes ethyl mercaptan, a highly odoriferous organic compound, injected on the surface into the compressed and/or ventilation airstreams. Upon smelling the stench, workers evacuate the mine according to an emergency preplan.Although the stench system has been used successfully for over 60 yr, it has several serious shortcomings, owing to certain chemical properties of ethyl mercaptan and to certain performance characteristics and limitations of present injection systems.Recent Bureau research succeeded in upgrading the overall safety and effectiveness of the stench system through the use of a superior stench odorant and the development of improved stench injection equipment (1).4 This research has also investigated a specialized computer simulation model capable of calculating the precise concentration of stench in any mine ventilation network branch at any time after stench release (2). An adaptation of the computer model now enables the analysis of stench system and ventilation system interactions under the influence of a mine fire."

Jan 1, 1987

By D. F. Machuca-Mory

A change of support model consists of a procedure to change a stationary histogram at a small data scale to represent a larger scale; typically a distribution of sample drill-hole data is changed to represent a chosen selective mining unit (SMU) scale. Most grade variables average arithmetically. Thus, the mean stays the same for different scales, and the variance changes according to well-established theory using average variogram values. The longstanding challenge has been to predict how the shape of the histogram changes. The discrete gaussian model is widely used because it appears reasonable and introduces few artifacts; there are no artificial minimum/maximum values and the target mean and variance are reproduced exactly. The resulting distribution shape, however, is strongly dependent on a multivariate gaussian distribution. The authors generalize the approach by taking advantage of a property of the isofactorial model, which allows one to specify where the random function falls on the spectrum between a low-entropy mosaic model and a maximum-entropy diffusion model. A measure of dissemination (MD) is computed using a ratio of the madogram and the variogram. The change of support algorithm is developed that uses a variable measure of dissemination (VMD) that is easily calculated and fit to data from the deposit. The resulting VMD change of support model is very flexible to represent different mineralization styles encountered in practice; global predictions of recoverable reserves are more accurate and decision-making is improved. A number of real examples are shown to demonstrate the approach.

Jan 1, 2008

By H Aral

A rotating magnetic field can be produced in a magnetic separator by using a magnet rotor fitted with alternate north-south magnetic poles, similar to the rotors currently used in modern eddy current separators. Rotation of the magnetic field causes ferromagnetic particles to rotate during magnetic separation. The particle rotation can then be used simply to remove entrapment during a conventional attraction magnetic separation (RMF lift separation), or it can be used to roll particles away from non-rotating particles, and to move them out of the separator under their own rotation (RMF rotation separation). RMF (rotating magnetic field) separation is a separation for ferromagnetic particles. These particles have a very ordered magnetism that is locked into directions of easy magnetisation in the crystal. As a result, if the external field rotates, the particles attempt to rotate with it. RMF separation uses this fact to rotate the ferromagnetic particles in a rotating field. In contrast, paramagnetic particles have a magnetism that can point in any direction with almost equal ease, and these will not rotate in a rotating field. By making use of this difference in magnetic properties, RMF rotation separation can separate ferromagnetic particles from paramagnetic, even when the particles have similar susceptibilities. Some particles such as both chrome spinel and ilmenite can contain ferromagnetic regions within a paramagnetic matrix. These ferromagnetic regions can vary from very small regions dispersed throughout the crystal, through thin lamellae, to larger more bulky regions. Although most natural ilmenite is ferromagnetic and generally has a higher magnetic susceptibility than paramagnetic chrome spinel, the susceptibility ranges for the two minerals overlap considerably (Allen, 2000a) due to the presence of these ferromagnetic elements, frequently making the conventional magnetic separation of these two minerals impractical. It is known that roasting a mixture of ilmenite and chrome spinel particles increases the magnetic susceptibility of the ilmenite while leaving the spinel susceptibility substantially unchanged. This makes the use of conventional (susceptibility attraction) magnetic separation more practical for the separation of these two minerals. However, very little is known about the effects of roasting on the response of ilmenite and spinel particles to a rotating magnetic field. For example, although the optimal ilmenite roasting conditions for conventional magnetic separation are quite well established such conditions may or may not be optimal for RMF rotation separation. Low intensity conventional magnetic separation on the basis of magnetic susceptibility can be made more accurate if it is carried out in a rotating field, because the rapid spinning of the separating particles prevents the formation of magnetic flocs, and reduces entrapment and entrainment. Medium intensity RMF rotation-only separation (no attraction component) has the ability to separate rotating (ferromagnetic) from non-rotating (paramagnetic) particles, irrespective of their relative magnetic susceptibilities. RMF rotation separation is of particular interest in this case because ilmenite particles generally rotate much better than the mainly paramagnetic chrome spinel particles, and roasting could enhance this difference further. Further information on the use of RMF to separate minerals can be found in Allen (2000a; b and c). The aim of this series of tests on a number of Australian ilmenites was to compare some different oxidising and reducing roast methods and to establish whether the use of RMF rotation separation improves the chrome spinel rejection.

Jan 1, 2001

By Youze Xu

The leaching and reduction of Cr(VI) in soils contaminated by chromium-containing slag were investigated with column experiments. The results showed that Cr(VI) concentration in leachate decreased from 988 mg L-1 to 407 mg L-1 after 7 days when water was used as leaching agent. However, Cr(VI) in leachate in culture medium treatment was not detected at above periods. In comparison, Cr(VI) concentration in leachate from autoclaved soil remained 398 mg L-1 at the end of experiment. The results indicated that the indigenous microorganism was capable of reducing Cr(VI). The amount of Cr(VI) reduction was 335 mg at the whole experiment period and the reduction rate was 67.09 mg d-1. Carbon supply showed minor effect on Cr(VI) reduction. However the reduction capability of Cr(VI) could be improved by combination of the carbon and the nitrogen. The optimal quantity was 5 g L-1 of yeast extract and 4 g L-1 of glucose.

Jan 1, 2009

Recycling and Recovering Fine Particles from Auto Shredding Residue (ASR/SR) to Conserve Raw Materials and Protect Environment

Sep 13, 2010

PolyMet Mining is developing the NorthMet property near Duluth, Minnesota. Laboratory investigations had led to the development of the PLATSOL process to dissolve in one step the base metals (copper and nickel) as well as the gold and PGM’s. To complete the pre-feasibility study, a fully integrated ten-day pilot plant trial was undertaken, comprising of: high temperature (>220ºC) pressure oxidation in the presence of 5-10 g/L chloride (the PLATSOL process), followed by solid/liquid separation, gold plus PGM’s recovery from solution, conventional Cu SX/EW and recycling of the copper raffinate to the autoclave. The concentrate tested was a NorthMet bulk flotation concentrate assaying 14.7% Cu, 3.05% Ni, 0.14% Co, 26.7% S, 1.4 g/t Au, 2.2 g/t Pt and 9.9 g/t Pd. Laboratory results were fully confirmed and with minor adjustments of the laboratory PLATSOL® conditions, the following leach extractions were obtained during the pilot plant trial: Cu 99.6%, Ni 98.9%, Co 96%, Pd 94.6%, Pt 96% and Au 89.4%.

Jan 1, 2001

By J. West

For many years line-of-sight (LOS) issues for underground mobile equipment is a growing focus of research. This research is a result of the numerous fatalities and injuries which occur in the mining industry and which are related to poor operator LOS. Three assessment methods are currently used to assess operator LOS of underground mobile equipment. The light filament (LF) method is a hands-on assessment method that is performed in the field. This method is not evaluated in this paper. The laser scan (LS) method of assessing equipment is a quick and reliable method that comes from the need to evaluate vehicles already located in the field. The computer simulation (CS) method can assess LOS issues using a computer aided drawing (CAD) model, which is useful for assessing current or prototype models. The purpose of the current research is to compare and validate different operator LOS assessment methods. Comparison of the results of the LS and CS visibility plots yielded similar quantifiable results. A visual comparison of the results further illustrate that the LS and CS methods are acceptable assessment tools for mobile equipment operator LOS evaluation. The visibility assessment methods are now being prepared as guidelines for the mining industry to assess current and potential designs.

Jan 1, 2007

By Charles H. Minott, Michael J. Markow, Robert D. Wyatt, Fred Moavenzadeh

The substantial investment in tunnels anticipated in the next twenty years has focused new attention on the economics of tunnel construction itself and on some costly problems associated with underground work: the uncertain geologic conditions, the performance and adaptability of men and equipment, and the need for quicker, more efficient excavation methods. There also exists a need to develop better ways of estimating tunnel construction. Inaccuracies in current bid estimates stem from a number of causes, among them (1) the effects of geologic conditions, which are not adequately known prior to construction, (2) the dependence of actual cost on the construction method used and on the interactions among the operations occurring underground, and (3) the reliability of tunneling equipment. Inability to estimate final costs for conventional tunneling more accurately has in turn caused difficulty in gauging the costs and benefits attributable to new tunneling technologies either under development or for which R&D programs are planned. ATTRIBUTES OF THE TUNNEL COST MODEL This paper presents a computer based Tunnel Cost Model (TCM) which quantitatively assesses the uncertainties inherent in underground work, and is detailed enough to aid in preparing estimates or bids. The model employs appropriate techniques of subjective (or "degree of belief") probability and computer simulation of tunnel construction operations to estimate distributions of total tunnel

Jan 1, 1974

Paiam is a new township in the high mountains of Papua New Guinea built in association with the Porgera Joint Venture mine, one of the world's largest and most remote open cut gold mines. The Paiam town project is an interesting and genuine attempt at building sustainability into a community associated with a mine. A result of a tri-party agreement between a resource developer, government and land owners, this town is a good example of appropriate utilisation of benefits, obtained from resource development, directed at achieving a sustainable environment at local and regional levels.   Mining brought technology and income to the region, although as most mine staff fly directly in and out, local landowners considered there was a limited flow of benefits within the nearby townships. An agreement with government and mine was reached that more mine personnel and their families be housed locally. In 1998, we, a firm of Landscape Architects and Heritage Consultants based in Cairns, Queensland, were engaged to assist develop the fledgling town of Paiam into a livable and sustainable town and to produce material that would convey that information to stakeholders.   The design focused on establishing a sustainable town, with livability, urban form, aesthetics and opportunities for economic, social and cultural development. Aiming to be a livable town for locals and mine staff it included a market place designed as a focus for town life, essential for social cohesion and economic opportunities.   Located at 2200 m on steep rainforest clad topography, the town development has been laid out using an appropriate urban form based on organic village layouts. Clusters of houses allow for a common public area so children's play is monitored assisting with a sense of community similar to a traditional defensible village. Aesthetical consideration helps in developing community pride whilst maximising potential for development of a tourist industry.   Opportunities for ongoing economic development were incorporated in the design and construction process. These included developing skills and trades to service the region and to provide skills, development, income opportunities and infrastructure to last beyond mine closure. Administration procedures were set in place to form the basis of good governance.   The shift from traditional subsistence lifestyle to a sustainable community with traditional attributes was the project's goal and is being achieved.

Jun 1, 2010

By Frank D. Adams

The Island of Ceylon, which is one of the most beautiful possessions of the British Empire, has been an abode of man from the very earliest times. The Veddhas, a wild tribe of some 4500 people still living in the fastnesses of the jungle in east central portion of the island, are believed to represent a remnant of the oldest inhabitants of which we have any actual knowledge, but in the caves in which they live there are found the stone axes and other implements of Palaeolithic people who represent the first race of men who inhabited our globe, and of whom they may be, for all that is known, the direct descendants. About the fifth century before Christ there came the Aryan invaders, apparently from the north of India, who drove the Veddhas into the remote fastnesses of the jungle and developed the remarkable Singhalese civilization whose high character is demonstrated by the remarkable and very extensive system of irrigation works which they built up, and through which they made the island wonderfully productive. Great cities arose, some of which are believed to have had a population of over a million souls and whose temples and public buildings show that the people were accomplished architects and sculptors.

Jan 1, 1926

By R. V. Ramani

One area of study in the Coal Mine Injury Analysis project was to illustrate and enhance the ability of mine safety management personnel to apply analytical techniques to injury experience data and to justify requests for funds for safety enhancement actions on a cost/benefit and other quantitative basis. Four volumes of this final project report detail (1) the objective and scope of the mine safety management research, (2) the results of literature review, and case studies, and (3) models developed for mine safety management. The four volumes are titled as Volume III: Mine Safety Management, Volume IV: Analytical Techniques for Mine Safety Management; Volume V: Mine Safety Management Case Studies and Volume IX: Training Cost Model. In this volume, the following material is presented: (i) review of related literature, (ii) mathematical models to perform quantitative analyses of accident/ injury experience data using the tools and techniques of risk analysis, time series analysis, and the Markov process, and (iii) descriptions of the HDBSEL and ACIM programs which are used to perform accident/injury experience analyses and cost analyses, respectively.

Jan 1, 1993