Search Documents

By D C. Curry, M F. Young

Many flotation operations need to improve liberation to increase recovery, yet often plant operators are concerned that finer grinding will produce æslimesÆ with low flotation recovery. Yet simple circuits can be designed to give good liberation and excellent fines recovery. The economics of fine grinding has changed fundamentally with new stirred milling processes like the IsaMill. This has also transformed flotation design due to the clean surfaces produced in the inert grinding environment and the narrow size distribution produced by the IsaMill. Past poor experiences with æovergrindingÆ in flotation circuits was often due to the wide size distribution and the degradation of mineral surfaces produced by conventional devices using steel media, like ball mills and tower mills. The correct practice is to design both grinding and flotation together to suit the liberation characteristics of the ore. This may result in several stages of grinding and flotation, recovering mineral as soon as it is liberated, then applying further grinding energy only to those particles that still need liberation. Flotation then occurs in relatively narrow size bands and with minerals with similar liberation characteristics. Though the circuit may look more complex on paper, in reality it is far simpler to operate since each section performs predicably. Circuit design also needs to address materials handling. Finer particles affect froth handling and dewatering, but can still be easily handled by standard products with careful attention to design of launders, pumps and pumpboxes, and de-aeration before thickening and filtering. Excellent examples of designing circuits to include ultrafine grinding include Mt Isa and McArthur River (MRM). In the last decade these operations have produced over ten million tonnes of concentrate with an average grain size below 10 ¦m and above 80 per cent recovery. At Mt Isa, zinc recovery was increased by ten per cent by applying fine grinding to existing poorly liberated streams. In fact, grinding finer in the IsaMill actually improved the recovery of fine particles by ten per cent, and maximum particle flotation recovery occurs for 10 ¦m particles. A more recent example is the flotation of Platinum Group Metals (PGMs). The use of conventional ball or tower milling to improve liberation is severely limited by the impact of commonly associated chromite on classification, and degradation of flotation performance by the steel grinding environment. The ability of open circuit IsaMills to deliver a narrowly sized ultrafine product with clean mineral surfaces is transforming the design of platinum flotation circuits. The science and practice of fine-grained flotation is now thoroughly proven. The availability of the 2.6 MW IsaMill has made ultra fine grinding a practical tool for flotation plant design. It is expected to become a standard choice for future applications of both fine-grained ores and for minerals with difficult flotation characteristics.

Jan 1, 2005

"How Wall Street Darling Molycorp Undermined the U.S. Economy, Degraded our National Security and Distorted the Global Economic Balance and How These Falsehoods Continue to be Promoted Even Today INTRODUCTION & SUMMARY In 2007 the Molycorp Mountain Pass rare earth mine was resurrected from its desert-grave in California by its then-owner Chevron Mining. Responding to elevated rare earth prices Chevron began processing on-site rare earth concentrates left over from past mining operations that were terminated in 1998i. Chinese demand had sparked what was being described as a commodities super-cycleii. Commodity prices were on the move. Wall Street smelled opportunity. In 2008 Goldman Sachs, Pegasus Partners, Resource Capital Funds, Traxys North America LLC and Carint Group LLC acquired the mining assets from Chevron. In an environment of ever-declining ethical standards and regulatory consequences the private capital group and their investment bankers would bring Molycorp to market. Molycorp, with its high powered investment banking team of Morgan Stanley and J.P. Morganiii, easily dominated the contest. Molycorp promoted itself, largely based on its past operating history and proven reserves, as the best company to challenge China’s monopoly control over the production of rare earths: a group of elements critical to most advanced technologies and U.S. defense systemsiv. Most of Wall Street’s hottest investment sectors were dependent on these materials: alternative energy, green technologies, computing, personal communications, advanced electronics and defense systems. By late 2010 there were dozens of prospective rare earth start-up ‘mining companies’ seeking capital. Eventually the number of prospective rare earth mining companies seeking capital exceeded 400, despite the reality that supply requirements of this market were disproportionally small when compared to other natural resource sectorsv. In the world of finance ‘smart money’ picks the winners. Consequently just twovi projects attracted nearly all of the capital (Molycorp and Lynas). Wall street picked Molycorpvii. This paper will primarily focus on Molycorp. By early 2010 the words “Molycorp” and “Rare Earths” electrified many people in the mining industry, most non-Chinese manufacturing technology companies, U.S. & allied defense contractors, technocrats in the U.S. national security community and eager investors across most of the world’s stock markets. It was the hottest story of the yearviii. The financial, technology and defense press coverage verged on euphoric: heaping fuel on fuel until the highly combustible Molycorp-pyre cast a long shadow over all of its rivalsix. When the IPO match was lit the spectacular flaming pyre sucked all of the oxygen out of the rare earth spacex. Molycorp was ranked the most lucrative IPO of 2010, resulting in record breaking profits to its private investors and massive returns for its early stock holding investors."

Jan 1, 2017

By William H. Pomroy

This report describes research leading to the design, prototype fabrication, and successful in-mine proof-of-concept testing of two improved stench fire warning systems for underground noncoal mines. The stench system, widely used in underground noncoal mines to warn of fire or other emergency suffers several serious shortcomings, including the toxicity of the odorant leading to debility in miners; reactivity of the odorant with iron oxide, resulting in unreliable warning because the odor may fade when transported long distances in steel pipe; lack of control over the rate at which agent is released into the air-stream, resulting in some work areas receiving unbearably high stench concentrations and other areas being missed altogether; lack of visual indication of system status, valve positions, or proper system operation; and excessively long stench transit times. In 1979, the Bureau of Mines, U.S. Department of the Interior, began research to upgrade the stench warning system. Two systems were subsequently developed which offer significant advantages over current systems.

Jan 1, 1984

By Geoffrey Birch

A skilled and efficient workforce is a pre-requisite for the success of modern construction companies. The drive for improved performance, innovation and best value must be matched by the enhanced skills of the construction personnel. Training has been accepted as one of the essential cost effective elements to achieve these goals. The foundation industry demands particular specialist skills and requires focused training for its dedicated operatives. The introduction and development of specific training qualifications for the foundation sector is providing significant benefits.

Jan 1, 2000

By D. E. Pollock, J. A. Organiscak

Water sprays and water powered scrubbers have both been utilized in the mining and milling industry to suppress airborne dust. Unconfined water sprays operated at lower water pressures of ?689 kPa (?100 psig) can be very effective at wetting the mine product at the dust source and significantly reducing the amount of respirable dust that becomes airborne. However, unconfined waters sprays can be somewhat ineffective in actually removing airborne dust from the air. On the other hand, water powered scrubbers operating at higher water pressures of ?1,724 kPa (?250 psig) in physical enclosures or ducts have previously been demonstrated to be very effective in removing airborne dust from the air. These higher operating water pressures are uncommon in many mines and mills, so their use is limited. The National Institute for Occupational Safety and Health (NIOSH) recently investigated the performance of a lower-pressure, water powered inline series spray scrubber for removing localized airborne dust emitted at the source. Results showed noticeable improvements in airborne dust capture efficiency through the operation o f multiple inline series hollow cone spray nozzles within a round duct or pipe at the same water pressure as a single spray. Operating hollow cone spray(s) at higher water pressures noticeably improved airflow through the scrubber and yielded some additional scrubber efficiency improvements. Thus, in-line spray scrubber efficiency trade-offs were observed to be made by altering spray power components of water pressure and/or quantity (number of sprays). Results show that, on average, up to 0.23 and 0.32 m3/s (484 and 679 cu ft per min) of airflow at 0.81 and 0.69 dust capture efficiencies can be achieved with three 81° and 33°hollow cone inline series sprays, respectively, operating at 1,655 kPa (240 psig).

By Felipe De Lucio Pezet

"El presente trabajo desarrolla la teoría de los pernos sobre la roca como método de sostenimiento y control de los mismos dentro de la mina subterránena. La aplicación de este método desplaza a las técnicas convencionales como el enmaderado y la manpostería, las cuales fueron usadas principalmente en el siglo XIX. Asimismo, el método de empernar la roca introdujo un nuevo conocimiento ya que se basa en la resistencia a la tracción y en el principio de refuerzo de la roca in situ. De otro lado, los pernos de roca originales fueron perfeccionados y variaron sus elementos para usos específicos, así como se implantaron los pernos cementados con mortero de cementoPortland y con resinas orgánicas sintéticas."

Nov 20, 1967

By César Jaime Fernández

El presente texto describe los aspectos económicos, financieros y sociales de la actividad minera, cuyo objetivo es producir metales para su utilización en la supervivencia y desarrollo de la humanidad. En cuanto al primer aspecto, es generadora de ingresos suficientes para cubrir los costos y permitir que un excedente satisfaga a los factores humanos. Respecto al aspecto financiero comprende el costo de inversión y capital de trabajo. Finalmente, en el aspecto social se busca el incremento de la cultura y nivel de vida de los trabajadores y las comunidades afectadas.

Sep 1, 1977

By Mario Samamé Boggio

El presente texto señala la historia de la minería peruana a través de la época colonial y republicana. Esta última se divide en cinco períodos de los cuales solo se estudiarán dos en el trabajo. La primera etapa comprende de 1821- 1833 y desarrolla acciones para superar la crisis de la guerra, el salitre de Tarapacá, riqueza guanera y los ferrocarriles. La segunda etapa comprende de 1884- 1900 y señala la etapa de Grace, los ferrocarriles y la minería de plata.

Nov 1, 1983

The first part describes a model (the C model) based on the motion of the grinding charge. The charge is treated as a continuum, which allows analytical solutions to the equations that are developed. The C model is equally applicable to ball-, semi-autogenous and autogenous mills and contains a description of the power draw of both the cylindrical section and the cone-ends. Differences between the power draw of grate- and overflow-discharge mills are described from consideration of the different shapes and compositions of their charges. A large database of industrial mill data is used to demonstrate the accuracy of the model. Part 2 describes a simpler, empirical model (the E model) whose performance is based on that of the C model. The same database was used to assess the predictive capabilities of the E model. The model was shown to be only slightly less accurate than the C model despite its much simpler structure

Jun 18, 1905

By Alan Bateman

Introduction A few years ago the name Katanga recalled, to those interested in copper, a far-off country in central Africa where deposits of huge size were beginning to pour a stream of copper into the world's markets. But no one heard of the adjacent part of northern Rhodesia as a potential copper region. It was then a bush-covered wilderness, with a few lonely, widely-spaced villages, and here and there a copper prospect that created but little outside attention. There was also one struggling mine whose development created pessimism. The low-grade carbonate outcrops of Rhodesia did not compare favourably with the rich carbonate ores of Katanga. And, since Katanga was mining only oxidized ores, it was then thought that this adjacent region likewise would contain only oxidized ores. The one mine that had been started, Bwana M'Kubwa, was working on low-grade carbonate ore at a loss. The outlook was not promising. But, a little over three years ago, the aspect changed. The vision of one far-sighted engineer embraced the possibility that here copper sulphides might underlie those low-grade carbonate croppings. His courageous associates furnished the capital; drilling commenced, and the great Roan Antelope mine rapidly emerged. In quick succession, the N'Kana, Mufulira, N'Changa, N'Changa Extension, and Chambishi mines were heard from. Prospecting and development are now proceeding apace, towns are being hewn out of the virgin bush, plants are being reared, and ramifying branch railways are being pushed out from the single line of steel that now connects Rhodesia with the coasts to the south. A great new copper-mining centre is in the making, about which the world will hear much in the future. As with most new mining camps, rumors abound regarding its ore possibilities; some are correct, some are erroneous, and reliable information unfortunately is all too scanty.

Jan 1, 1930

By H von Blottnitz, J L. Broadhurst

Eco-efficiency has been proposed by the World Business Council on Sustainable Development as an environmental performance indicator framework that contributes to sustainability by assisting corporate decision makers improve the environmental performance of their operations and processes, while also extracting additional economic value. Given that the recent engagement of the minerals industry with sustainability has highlighted the need for requisite tools and methodologies, it is therefore of interest to assess whether eco-efficiency indicators can drive sustainability performance improvement during process design within the minerals industry. Previous work indicates that the choice of sustainability performance indicators to be used for decision making needs to be governed by the decision context; ie the performance indicators need to be fit-for-purpose. Here, the strengths and weaknesses of eco-efficiency indicators are analysed using case studies. First, a more rigorous definition of eco-efficiency indicators for the minerals industry is proposed based on indicators currently offered in the literature. Two case studies are then selected to reflect typical decision situations encountered within minerals process design. For each case study, eco-efficiency indicators are computed and are compared to more traditional graphical representations of the economic and environmental performance of process design alternatives considered. The sensitivity of these indicators to various process design parameters is also investigated. Results confirm that the meaningful application of eco-efficiency indicators is strongly dependent on the decision context in which the process data is generated. Results also show that eco-efficiency indicators can be related to technical process design parameters to allow for richer communication of performance information for various decision trade-offs; however, in some cases, graphical approaches that provide more insights into the environmental-financial trade-offs should be preferred. The research thus contributes to guiding the selection of the appropriate tools for more environmentally sustainable design of minerals beneficiation processes.

Jan 1, 2009

By Michael P. Hardy

The report described improvements and applications of the Hybrid Computer facility. Improvements implemented under U.S.B.M. Contract H0252035 included expansion of the capability to model nonlinear seam behavior, installation of a color video output display monitor, and further development of software capabilities. To demonstrate the capability of the system, firstly, the influence of nonlinear seam behavior response to the occurrence of coal mine bumps was fully investigated and secondly, the effect of improper mining sequence on bump occurrence was demonstrated. In addition, the system was applied to the analysis of a series of practical coal mine problems. Mines in three coal seams were analysed to investigate the parameters which contribute to the occurrence of coal mine bumps.

Jan 1, 1977

By J. L. Jambor, R. W. Boyle

"The Magnet Cove barite-sulphide deposit is a raking pipe-like body that replaced and partly filled a large brecciated zone at the junction of two faults at the contact between sedimentary rocks of the Horton and Windsor Groups of Mississippian age. The principal minerals in the deposit are siderite, barite, hematite, pyrite, marcasite, galena, sphalerite, chalcopyrite, tennantite, proustite, pearceite, acanthite and stromeyerite. The mineral assemblage and textural relationships indicate that the minerals were deposited from low-temperature solutions. The source of the elements in the deposit is believed to be the enclosing sedimentary rocks, with connate or ground waters as the transporting medium, and solubility products as the governing factor controlling the abundance and order of deposition of the minerals."

Jan 1, 1966

By Charles M. Wilk

"Mass stabilization involves mixing binding agents into marginal or contaminated soil to improve the subject material’s physical and/or chemical properties. This paper concentrates on the principles of soil mixing and benefits and application to new and existing rail right-of-way. Successfully applied in Scandinavia and other European countries, the soil mixing is now being applied in right of way in the northern latitudes of the U.S. and Canada. These regions have significant areas of “peaty” soils that can complicate construction and maintenance of rail and structure foundations. Mass stabilization can be used to improve the bearing strength of these soft soils for subsequent construction of railroads, pipelines, roads, and buildings. In civil engineering, the technology is often used to improve the construction properties such as bearing strength, of a marginal soil. In environmental engineering, stabilization is remediation treatment technology that protects human health and the environment by immobilizing hazardous constituents within the treated material. . The treatment is conducted while the subject material remains in-place (insitu). Mass Stabilization is often used to accomplish both civil and environmental purposes on the same project effectively addressing marginal soil while eliminating the expense of soil removal and replacement.This paper presents the principles of mass stabilization technology, implementation in the field and recent completed railway projects.The example rail projects will present the various benefits that soil mixing provides to railway construction and maintenance. Bench-scale studies and full scale implementation as well as soil construction properties before and after mass stabilization will be discussed. The paper and presentation will include information on the advantages of mixing methods and binding agent delivery systems.INTRODUCTIONNew or existing railroad right-of-ways may cross ground with low bearing capacity. Right of way subgrade undergo deflection (strain) as loads (stress) are applied (1). The amount of strain or deflection of the subgrade caused by loading of a train is proportional to the stiffness of the subgrade materials. Some soils, such as tamped ballast, are very stiff and resist loads well. Other soils such as soft clay, peat, or loose sand have low stiffness and undergo substantial movement under loads. It is very desirable to have the stiffest possible material in a track subgrade. Stiff subgrade material limits deflection under load, reducing track roughness and occurrence of track defects. Mass stabilization is a geotechnical method that can be used to improve the bearing capacity or stiffness of soil in these right-of-way. Mass stabilization involves mixing binding agents into soil subject to treatment while the soil remains in-place or insitu. Variations in the design or areas subject to treatment can be used to address transmission of vibration to adjacent structures."

Jan 1, 2017

By Rene Grabowski

Optimization of workflows and intelligent stock management; Slab stacking improvement by automated transport orders; and System automatically registers any slab movements even in manual operation. Case story: Steel producer ArcelorMittal Eisenhüttenstadt GmbH in Germany uses Primetals Technologie’s new stock yard logistics system in its finishing department. An exact image of its slab storage at any times is given by the warehouse logistics system to the company. It not only enhances the composition of the stacks of slabs, but also automates recording of manual restacking operations. Therefore the solution improves workflows and simplifies stock control. Cycle times have also been reduced due to the fact that the slabs can be charged to reheating furnaces ahead of the rolling mill due to less restacking operations within the slab storage. The expandable, modular system is based on the Siemens Simatic IT and Primetals Technologies’ IT4METALS Logistics product platform. It provides a large number of organizational and commercial features in the form of sophisticated graphics and tabular evaluations. For example, it can show how many crane movements have been made per shift for any category of slab, so that the time and cost for each operation can be calculated accurately.

Aug 16, 2017

By Derek Apela, Coralee Heske, Bunyamin Kahraman, Muhammad Adi

Effective blast fragmentation is essential in underground mining, as it directly influences downstream processing efficiency and operational expenses. This study investigates the application of Non-Newtonian Fluids (NNF) as stemming materials, presenting a novel method to enhance energy confinement, minimize environmental impact, and optimize blast performance. NNFs exhibit shear-thickening behaviour, enabling them to transition between fluid-like and solid-like states under stress, which renders them suitable for regulating explosive gas ejection during blasting. Field trials were performed by Vale Base Metals in Thompson, Manitoba, in their underground nickel mine to evaluate conventional slag stemming against NNF-based stemming in production-scale blasts. Emulsion explosives were employed, and blast performance was assessed through velocity of detonation (VOD) measurements, vibration monitoring, and AI-assisted fragmentation analysis using WipFrag. Preliminary results indicate that NNF stemming improves fragmentation, resulting in a reduction of D50 by as much as 38%, enhances energy confinement, and may decrease the incidence of hole plugging and re-drilling in subsequent blasts. This study presents an alternative to conventional stemming methods, highlighting potential advantages for enhanced safety, efficiency, and sustainability in blasting operations. Additional research and field trials are necessary to improve implementation protocols and facilitate the widespread adoption of this unique method in the mining sector.

May 4, 2025

By Glen C. Reed

"The Avon mica district of Latah County, Idaho, is situated on a heavily forested spur of the Thatuna Range at an average altitude of 4,000 feet. The nearest rail connection is at Avon, a small farming settlement 7 miles to the south. The main supply point is Moscow, Idaho, which is 35 miles by graveled and graded county roads from Avon.Discovery of mica-bearing pegmatites in 1885 was followed in 1888 by exploitation of several outcrop deposits. Although factual data are unavailable, past production appears to have been well in excess of $100,000. Recent production (September 191 to April 1945) amounted to 65,824.78 pounds of trimmed sheet mica and 33,294.17 pounds of punch mica having a total gross value of $434,298.The several properties of the district are variously owned by estates, individuals, and the State. When active, all wore under lease or sublease to individual operators.The deposits are in an area of pre-Cambrian schists adjacent to a small granitic outlier of the Idaho batholith. The pegmatites are nearly concordant in dip and strike to the foliation of the enclosing schists. The more persistent bodies are usually tabular, lenticular, or pegmatite. Individual dikes range in length from 10 feet or less to 300 feet.The recoverable crude mica content of the pegmatites ranges downward from a maximum of 115 pounds per ton of pegmatite mined. Material discarded in rifting and trimming operations further reduces recovery to a maximum of 5 pounds per ton -of pegmatite mined. The average recoverable sheet content of the 'recently operated .deposit is estimated at 2 pounds per ton of pegmatite -mined. Available data indicate that about 21 percent of the district's recent production of trimmed sheet mica has been ""Group A"" material suitable for exacting condenser requirements. A few of the dikes contain local concentrations of beryl.Reserves of the three known major deposits of the district are estimated at about 600 to 1,000 tons of combined ""indicated"" and ""inferred"" crude block mica. One of these deposits is inferred to contain between 150 and 450 tons of beryl.It is believed that those mica reserves are minable only under a cost-market price ratio similar to that established during 1943 and 1944. A small part of the reserves can be ""high-graded"" under the present price structure. Profitable recovery of the beryl would require a market price four to five times that paid in 1944.Preliminary examination of the Avon mica district was made by the Bureau of Mines in the summer and fall of 1942. A study of the Muscovite mine and a brief reconnaissance of the surrounding district led the Bureau to recommend that the district be explored by angle-dozer trenching."

Jul 1, 1946

By Yutaro Fukase

Various types of service robots have recently been developed for guarding facilities, caring for the elderly, carrying objects, and cleaning buildings. As barrier-free facilities improve and their use expands, these robots have more space within which to move inside buildings. Yet robots that move autonomously rely on position-detection systems. Though improving rapidly, these systems are far from perfect in determining positions in certain situations, especially when robots navigate large areas or cross various locations. Our group is working to solve this problem by developing a position-detection system using random-dot patterns on a floor. First, we construct a floor with a random-dot pattern and register the positions of all of the dots into a database. As the robot moves across the floor, a camera on the robot captures an image of the floor beneath it and crops the dot pattern in the image. The cropped dot pattern is matched to the dot patterns in the database to determine the position of the robot and the direction in which the robot is facing or moving. In this paper we propose a self-localization system and matching algorithms derived from a space technology and present the results of several experiments.

Aug 1, 2013

By Chris Harnan, Christophe Justino

The European Federation of Foundation Contractors (EFFC) and the Deep Foundations Institute (DFI) jointly published Edition 1 of the ‘EFFC/DFI Guide to Support Fluids for Deep Foundations’ in April 2019. This Guide was prepared by a Task Group comprising experts on deep foundations from contractors, materials suppliers, consultants and academics. The Guide builds on work carried out by the Tremie Concrete Guide Task Group and presented in Edition 2 of the Tremie Guide. The Paper discusses and describes the content of the Support Fluids Guide which presents the state of the art on support fluid management, as well as the R&D work currently being carried out and funded by EFFC and DFI sponsors through an ongoing Field Research Study (FRS) as well as a review of academic research linked to the EFFC/DFI joint effort aimed at improving knowledge and guidance on support fluids. The FRS and academic research will help to improve the understanding of relevant support fluid properties including stability of excavations, interface layer formation, effect of filter cake and the development of new sampling and testing methodology. The Paper also presents the initial findings from the FRS program as well as a discussion on the challenging aspects of support fluid management with emphasis on design, performance, testing, and the environment.

May 1, 2022

By F. W. Brackebusch

A unique machine has been designed for mining narrow veins. The machine, called the NONN, walks on the walls of the stope and carries a boom-mounted hydraulic impact breaker. The concept of walking on the walls allows an existing muck handling system such as LHDs to operate beneath the NOMN. The NOMM has four sets of legs which can be manipulated independently or concurrently to cause the carrier to walk in any direction and to turn sharp corners. The mining rate using the breasting method is targeted to be 25 t/hr.

Jan 1, 1990