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By S. L. Gay

The conventional mass-balance equations used as constraints can lead to flow estimate values of zero even though the flow estimates should be some positive number. This is because many of the constraint equations are satisfied if the flow rates are zero. The way to overcome the problem is to use a slightly different form of the equations. For example, rather than use the conservation of flow of solids as a constraint it is better to use the constraint that the percentage of solids going into a unit equals the percentage of solids coming out of the unit. Examples are given using mineral processing data sets from Mount Isa, Queensland, and Red Dog, Alaska

Jun 21, 1905

By G B. Arehart, S J. Mathews, J L. Mauk

The banded nature of the quartz veins which form the Empire lode at the Golden Cross mine, is perhaps their most striking feature. Petrographic studies show that significant differences occur between the bands in terms of textures, quartz grain size, calcite, adularia and kaolinite content, and the form, concentration and mineralogy of sulfide phases.   The d18Oquartz values of individual bands within the vein material range from 7.3-10.9ë. Calculations show that the d18Oquartz values can be adequately explained by temporal variations in the system temperature, boiling and/or variations in the systems fluid/rock ratios.

Jan 1, 1995

The Bureau of Mines has reviewed those portions of the "Tariff Schedules of the United States Annotated 1963" that are of interest to the minerals industry. This study shows to what extent rates of duty were altered (increased or decreased), and provides a bridge where possible from the old Schedule A classification sys tem to the new TSUS system of statistical reporting of import data. In general the new tariff has corrected previous classification defects and inconsistencies, but the rates of duties have not been materially changed.

Jan 1, 1965

By Dana T. Updyke

An evaluation was made of one of several improved underground communication systems sponsored by the U.S. Bureau of Mines. The system evaluated was installed in a typical metal/non-metal room and pillar mine and utilized UHF repeaters connected to a unique distributed antenna and passive reflector system which provided mine-wide communications. A microprocessor controlled data collection system was assembled and installed for the evaluation. Data consisting principally or times and durations of messages and identities of the originating transceivers was collected between February and August of 1982 (6 mos.). Analysis of the data shows that the principal benefits are reduction in time required for unscheduled maintenance and repair, enhancement of safety, and better coordination of production activities. A cost benefit analysis shows a net benefit over cost, although it is also concluded that the capacity of the system is greater than can be justified by current activity in the mine.

Jan 1, 1983

By F. J. Perzak

The Bureau of Mines conducted a flammability study of plastic ventilation ducts. Six rigid 16-in-diam fiberglass-reinforced plastic ducts from five manufacturers were examined using laboratory-scale, large-scale, and full-scale fire tests. The laboratory-scale tests included the American Society for Testing and Materials E162 radiant panel test, the E2863 oxygen index test, and the standardized small-scale flammability test (S3FT) developed by the Mine Safety and Health Administration (MSHA), U.S. Department of Labor, and replicated by the Bureau of Mines. Ten-foot lengths of the same ducts were also subjected to a large-scale vertical fire test, and 20-to 30-ft lengths were tested in a full-scale in-mine fire test at the Bureau's Lake Lynn Laboratory mine. The data from the laboratory-scale radiant panel test and oxygen index test indicated that the ducts were fire-resistant, However, five of the six ducts failed the S3FT and vertical fire tests, and four of the ducts failed the full-scale in-mine tests with flame propagation rates that ranged from 3 to 10 ft/min. The results indicate the need for improved fire-resistant plastic ducts. The good agreement between the S3FT re-sults and the vertical and full-scale tests show that the S3FT provides a good indication of the flammability of fiberglass-reinforced plastic ducting under realistic fire conditions.

Jan 1, 1987

By Michael J. Beus

This Bureau of Mines report describes the development of load cells for measuring compressive loads in timber and lock-bolt support systems commonly used in. coal; metal, and nonmetal mines Design and evaluation is covered in detail to insure a reliable, accurate, and practical instrumentation scheme. The load cells are relatively inexpensive and adaptable to various size support systems. User-oriented procedures are emphasized, and design equations were reduced to a series of nomographs. Laboratory evaluation, destructive testing, environmental testing, and tests to determine the effect of extraneous loads were conducted. Field performance was evaluated in conjunction with ongoing Bureau projects at a metal mine in North Idaho and a coal mine in Utah. Load cells utilizing a titanium alloy as the cell body and weldable strain gages as the strain-sensing components satisfied the basic design and performance criteria, and with minor design modifications, the load cells can be adapted to many mining applications.

Jan 1, 1974

The Hyde-Macraes Shear Zone (HMSZ) is low angle, duplex thrust system that has developed in a graphitic pelite schist within the Otago schist belt, New Zealand . At Round Hill lateral ramps have developed parallel to the movement direction between+ the footwall and hangingwall shears. These structures exhibit normal oblique-slip displacement which has been an important mechanism for creating space in an otherwise compressional system. Gold-bearing quartz veins were emplaced along the boundary shears and lateral ramps during thrusting. Gold within the lateral ramps is coarse (up to 300 microns) however hanging wall cataclasite development in the boundary shears after the gold was deposited has reduced the grainzise of most of the gold to less than one micron. This bimodal gold distribution has metallurgical implications with respect to the maximisation of gold recovery at Macraes.

Jan 1, 1993

By Harold L. Rhodes

The Bureau of Mines has developed a method for determining the H2S content in natural gas samples. A gas chromatograph with a flame photometric detector was used to analyze samples with H2S concentrations ranging from 5,000 ppm to a minimum detectable limit of 0.01 ppm. A mass spectrometer was used to analyze samples containing H2S in amounts greater than 5,000 ppm. Methods are presented for preparing containers for H2S samples and for preparing standards using partial pressure and weighed standard methods, Sample collection techniques are discussed, as are analytical results which illustrate the loss of H2S while in the sample container and provide a basis for evaluating containers used for sampling and standard preparation.

Jan 1, 1979

By S. Watkins, D. Apel, B. Gray, R. Moss

Currently, there are several techniques and technologies available which are used by mining industry in its attempts to remotely monitor the ground movements both at surface and underground mines. The currently available remote distance meters and distance change monitors mainly use phase change and time-of-flight techniques. The described monitor uses triangulation technique to track position of an optical spot projection and then image processing to measure mine wall movements. The system can be easily automated and poses no obstruction to mine traffic. The position of an off-normal laser spot will shift as the target wall moves. The described ground movement monitoring system has potential for superior accuracy and target monitoring can be made through air (gaseous) or other transparent media. The theoretical accuracy and range of this system depends solely on the resolution and focal length of the camera being used. The remote capabilities of the system make it uniquely suited to applications where monitoring is required in high-traffic, inaccessible, or unstable and dangerous areas of a mine.

Jan 1, 2007

By T. Grammatikopoulos, A. McKen, O. Christiansen

Vanadium mineralization occurs in oxide-rich horizons within layered metagabbro zones of the Sinarsuk deposit, West Greenland. The main oxide minerals are vanadiferous magnetite and ilmenite, comprising 30% to 90% of the rock volume and the ratio of magnetite to ilmenite ranges from 3:2 to 4:1. Ore microscopy shows that magnetite and ilmenite vary between 0.2 mm and 4.5 mm in grain size, but locally they are coarser grained. Grains are subhedral to euhedral and annealed suggesting that they will liberate very well upon grinding. Electron microprobe analyses indicate that magnetite grains are homogeneous and have a vanadium content, in different mineralized samples, ranging from 1.93 wt% to 2.68 wt% equivalent V2O5. Ilmenite hosts abundant and variably sized hematite lamellae, and it has vanadium contents ranging from 0.32 wt% to 0.59 wt% equivalent V2O5. Preliminary beneficiation of two composite bulk samples shows the samples can be beneficiated fairly easily using low-intensity magnetic separation at a coarse grind (106 microns to 600 microns) to yield a vanadiferous magnetite concentrate. The presence of hematite lamellae in ilmenite prevents recovery of a satisfactory ilmenite concentrate. The most likely beneficiation flowsheet would encompass a primary mill (SAG or rod mill), which would grind to about 600 microns, followed by a rougher magnetic separation stage. The rougher magnetic concentrate would be reground in a ball mill until suitable liberation is achieved. The reground material would then be cleaned in further LIMS stages. However, further laboratory testing is required to establish the final beneficiation program. This work demonstrates the value of mineralogical investigation in guiding and explaining the results of beneficiation processes.

Jan 1, 2002

By D. K. Steele

An 18-in-diam column water elutriator was designed, tested, and operated by the Bureau of Mines for recovering nonferrous mixed metals from automobile shredder rejects. The waver elutriator separated metals from nonmetals contained in shredded nonmagnetic rejects. The unit was constructed and integrated into a local automobile shredding operation. Nonmagnetic rejects from the automobile shredder were fed onto the surface of a column of rising water. Dense materials fell through the rising water and were collected as a sink product at the bottom of the column; medium-density materials were removed as an intermediate product in a water flow through a discharge port located between the overflow and sink; and light materials were immediately carried out in the overflowing water at the top of the column as a float product. Nearly 99 pct of the mixed metals were recovered from the nonmagnetic rejects as a 70-pct-metal concentrate. Other operating conditions yielded a 93.7-pct-pure-metal product resulting in a 93.1-pct metal recovery. Float rejects are combustibles, light plastics, foam rubber, and minimal amounts of coated and uncoated copper wire. The middling discharge contained mainly medium-density rubber, plastics, glass, rock, coated and uncoated copper wire, and frequently some thin-sheet stainless steel and wrought aluminum. Maximum metal recovery in the operating program was achieved using a water velocity of 52 fpm (650 gpm). Maximum purity was obtained with a velocity of 88 fpm (1,100 gpm). .Water was recycled through a 12,000-gal baffled clarifying tank. Entrainment water losses with the float and middling rejects averaged 50 gpt of reject feed. Records maintained by the shredder operator show a 34-pct increase in nonmagnetic metals recovery during a 1-yr operation of the water elutriator as compared to recoveries from a previously used air classification system.

Jan 1, 1983

By K. C. Tran

This paper reviews the advancement of measurement technologies for the control of raw materials processes in the basic industries. The combination of digital technology and on line spectroscopy enables the development of intelligent instruments for composition and particle size analyses in real- time high- frequency control conditions. In many industries, the applications result in productivity improvement and energy savings. Plant specific examples include operating experience and benefits realized in sorting, blending and beneficiation processes. Instruments of the future not only measure specific parameters of the process and monitor its own health combined with self-corrective mechanics but also acts with intelligence to effect the quality of the process or regulate the primary apparatus.

Jan 1, 2001

By Bradley Stoughton

(Cleveland Meeting, October, 1912.) [SECRETARY'S NOTE.-To avoid repetition of foot-notes, references to authorities are made in this paper by means of figures, referring to a numbered list in the appendix.-J. S.] INTRODUCTION. THIS paper gives the results : first, of a research into the somewhat extensive literature of titanium; and second, of a series of original tests upon the effect of titanium on iron castings. New investigations have also been made upon the effect of titanium on steel, but I hope to treat this subject in an independent paper at some later date, and, therefore, will not discuss the experiments in detail here. The combined results of this study, which extended over a period of more than two years, can be briefly summarized as follows: 1. Steel or cast-iron, in which the titanium is properly proportioned, and which has been properly treated, is improved in strength, toughness, and durability against wear, such as, for example, the wear of railroad-rails, of steel and chilled-iron .rolls, car-wheels, etc. 2. These improvements seem to be caused, not so much by the direct effect of titanium on the metal, as by its cleansing influence in removing harmful impurities, such as oxygen and oxides, nitrogen, occluded slags, and perhaps also sulphur. It appears also to reduce segregation, which would contribute to the same end. 3. In order that its effects may be fully realized, the treatment of steel or iron with titanium must be correctly performed. There are a few simple, but essential, details to be observed; if they are neglected, the best results cannot be expected. To illustrate by an example : A series of tests on cast iron

Nov 1, 1912

By D. R. Hack

Increased consumption of concrete in the Pacific Northwest has pushed aggregate resource development pressure from urban areas west of the Cascade Range to rural areas east of the Cascades. Some recent development has focused on barge and rail accessible off-reservation Indian allotments that are exempt from state and county regulations. These lands have their own unique set of challenges, especially when Federal and Tribal governments have conflicting goals and attitudes pertaining to resource development. This paper discusses issues of leasing, reclamation, Federal vs. Tribal authority, cultural resources, and the history of allotment.

Jan 1, 2002

By R. H. Colquhoun, A. W. Bolland, H. J. H. Pieterse

"American Barrick Resources Corporation acquired the goldstrike property in north eastern Nevada in early 1987. Since that time, the company has undertaken an extensive development program. This paper will overview the milling, autoclaving, and heap leaching facilities which are part of the $400-million Betze development plan. Gold production at the Mine has increased from 40,000 ounces per annum in 1987 to more than 500,000 ounces in 1991. And in 1992 Goldstrike will be the single largest North American gold mine when it produces 1,000,000 ounces.1. SUMMARYAmerican Barrick Resources Corporation acquired the Goldstrike property in northeastern Nevada in early 1987. Since that time, the company has undertaken an extensive development program. This paper will overview the milling, autoclaving, and heap leaching facilities which are part of the four year, $440- million Betze Development Plan. Gold production at the Goldstrike Mine has increased from 40,000 ounces per annum in 1987 to more than 500,000 ounces in 1991. In 1992, Goldstrike will be one of the largest North American gold mines, when it produces appro approximately 1,000,000 ounces.2. INTRODUCTIONAmerican Barrick Resources Corporation is in the process of developing the Betze gold deposit, located on Barrick's Goldstrike property in the Carlin area of Nevada, U.S.A.The Goldstrike Mine has 17.9 million ounces of proven and probable reserves and an additional 460,000 ounces of possible reserves. Additionally, the Purple Vein deposit, one mile north of the Mine, is expected to add at least 4 million ounces of reserves by year end 1991.The Goldstrike ore body contains both oxide and sulphide ore. The largest part of the reserves are contained in the high grade, deep sulphide ore. Mining of the sulphide ore contained in the Betze deposit involves the removal of large quantities of overlying oxide ore. Oxide ore is treated through one of the following processes:-"

Jan 1, 1992

By P. Ashayer, J. Curran

Introduction Rockfalls occur when rocks or boulders detach from mountains or hills and tumble down. They can pose significant hazards to infrastructure such as highways, buildings, and mine open pits, and they sometimes result in personal injury or death. Prediction of rockfalls is a difficult task. Slopes that are at risk of rockfall have highly variable geometries. The location, mass, and shape of the rocks that might dislodge and fall are uncertain. Moreover, the materials that make up a slope can vary considerably from one section to another. Furthermore, the relevant material properties are usually not well known. Performing probabilistic simulations of rockfalls, combined with proper statistical analyses, has proven to be an effective and acceptable method for dealing with these difficulties [1, 2, 3]. The movements of a falling rock can be classified as freefall, bouncing, sliding, toppling, or rolling. The falling trajectory is controlled mainly by the geometry of the slope, the block shape, and the energy dissipated at each contact of the block with the slope. A rockfall model is evaluated based on its ability to efficiently predict the velocity, frequency, height of bounce, and run-out distance of falling rocks. With this information, the engineer can design remedial measures such as restraining nets and ditches. Most of the existing rockfall simulators are based on particle models that consider the falling rock as an infinitesimal particle with a mass, called the lumped mass or stereomechanical models [1, 2, 3, 4]. Other models involve hybrid methods relying on simplified assumptions. The most common hybrid methods are based on contact searching for the movement of a dimensionless object and incorporate some aspects of rigid body impact for bouncing [5, 6, 7]. There are also some rigid body models in the literature that employ simplified versions of rigid body models [8, 9]. This study applies a more sophisticated rigid body theory based on rigid body impact mechanics (RBIM), which was developed by Stronge [10, 11, 12]. The new theory captures all modes of rigid body movement. Due to the importance of the rock geometry, single impacts of ellipsoidal and prismatic rocks with rectangular cross sections are investigated. The effect of rock slenderness on rebound velocities and energies is also investigated for ellipsoidal rocks. The correspondence between the model parameters and the data from the rockfall literature data will be discussed.

Jan 1, 2007

By Paul Lynch

"Since being reported to the 2012 UMI in Shanghai, the Cook Islands has been steadily developing for the commencement of it Seabed Minerals sector in its large Exclusive Economic Zone which contain a vast and unique Manganese Nodule resource, estimated at 10 billion tonnes1. At the 2013 UMI in Brazil, it was reported that the Seabed Minerals Act had commenced and all the necessary complex Technical aspects of this developmental work was being undertaken. At the 2014 UMI in Portugal, full details of the final developments leading to the opening of the Tender of Exploration Blocks in the Cook Islands EEZ will be presented in a brief but comprehensive method, using Poster displays, Powerpoint and active Website interaction. This will show the drafted Regulations, prepared on best international standards, to address both Licencing and Environmental requirements, to give clarity and security to the Resources Owner, industry and stakeholders. This work in being coordinated by the Cook Islands Seabed Minerals Authority, with the valuable collaboration of many international, regional and national stakeholders, including the Cook Islands NGOs, Marine Resources, Marine Park and National Environment Service."

Sep 1, 2014

By D. F. Malan, M. Grave, J. A. L. Napier

Previous fundamental research projects have indicated the value of continuous closure measurements in deep tabular excavations for improved support design, hazard assessment and for quantifying the effect of seismicity on stope closure. This paper describes further measurements in a VCR stope to validate some of the earlier findings. Calculation of the closure ratio showed that it is a good measure to identify different ground conditions and possible hazards. This work was supported by numerical modelling results, which showed that the closure ratio is very useful in discriminating the response of different geotechnical environments. Des projets précédents de recherche fondamentale ont démontré la valeur de mesures continues de fermeture dans le cas de profondes excavations tabulaires pour une conception améliorée du soutien, de l’évaluation du danger et pour quantifier l’effet de la séismicité sur l'affaissement du toit d’un chantier d’abattage. Le présent document décrit d’autres mesures dans un chantier d’abattage VCR afin de valider certaines des conclusions précédemment formulées. Le calcul du degré d'affaissement montre qu’il y va de soi d’identifier différentes conditions de sol ainsi que les dangers possibles. Les présents travaux ont été confirmés par des résultats de modélisation numérique, lesquels ont démontré que le taux d'affaissement est très utile quant à discerner la réponse dans des environnements géotechniques différents. Vorherige Forschungsprojekte haben den Wert von kontinuierlichen Setzungsmessungen im tiefen Sudafrikanischen Strebabbau angedeutet, vor allem fur Ausbaudesign und Risikobewertung, als auch fur die quantitative Bestimmungen der seismizitatsabhangigen Setzung. Dieses Referat beschreibt weitere Messungen in einer VCR Grube um fruhere Bestimmungen zu bewerten. Dass errechnete Konvergenzverhaltniss erweiste sich als eine gute Massnahme zur bestimmung von geotechnischen Zonen und moglichen Risiken. Numerische Analyse unterstutzte die vorliegende Arbeit und deutete darauf, dass das Konvergenzverhaltniss sehr brauchbar ist um Verhaltensunterschiede der geotechnischen Zonen zu erproben

Jan 1, 2003

Newcrest Mining is one of the leading independent gold producers in Australia thanks in large part to its Cadia Valley operations. It is the largest gold and copper producer in New South Wales and one of the largest in Australia. This year Newcrest will expand its operations with a A$545-million expansion in the area. The Cadia Valley is approximately 250 km (155 miles) west of Sydney. The province presently includes the Cadia Hill opencut mine and the Ridgeway underground mine. With a significant mineralized system to the east of Cadia Hill and a mineral resource below Ridgeway, Cadia Valley has the potential to underpin Newcrest?s production for up to 30 years. In 2007, total gold production for the company in-creased to more than 50 t (1.6 million oz) and cash flow increased by 47 percent, according to the company?s annual report. The history of mining in the area dates back to 1851, but Newcrest?s history is young. In 1990, Newcrest commenced activities in the Cadia Valley. In 1992, Cadia Hill was discovered, with the discovery of Cadia East (1995) and Ridgeway (1996) following close behind. In 1998, the Cadia Hill openpit mine was commissioned. In 2002, the Ridgeway underground mine was commissioned and in 2007 the company?s board of directors approved an A$545 million development of the Ridgeway Deeps. The Ridgeway underground mine is located adjacent to Cadia Hill. The Ridgeway orebody has no surface expression but lies approximately 500 m (1,640 ft) below the surface and resembles an inverted teardrop. It measures approximately 450 m (1,476 ft) by 250 m (820 ft) and extends in excess of 850 m (2,788 ft) in depth. Ridgeway is a sublevel caving operation. Crushed ore from underground is delivered by conveyor to a surface stockpile, adjacent to the Ridgeway concentrator. Using similar processes to the adjacent Cadia Hill concentrator, gold and copper are recovered in a conventional flotation circuit to produce a copper concentrate containing elevated gold levels. Ridgeway concentrate is combined with the Cadia Hill concentrate before it is pumped to the filtration plant in

Jan 1, 2008

By K. Awuah-Offei

Long-term production scheduling optimization has been a challenging issue for the mining industry because of the size and complexity of the problem. The current planning algorithms have limitations in terms of addressing the stochastic variables underlying the mine planning problem. In this paper, an intelligent agent-based mine planning framework based on reinforcement learning is introduced. The long-term mine planning is modelled as a dynamic decision network. The intelligent agent interacts with the block model by means of a stochastic simulation and employs a Q-learning algorithm to learn the sequence of pushbacks that maximizes the net present value of the mining operation. The intelligent open pit simulator (IOPS) was implemented with an object-oriented design in Java®. A comparative application case study was carried out to verify and validate the models. The proposed method was used in planning an iron ore deposit and the results were compared to the Milawa scheduler used in Whittle® software. The outcome of the study demonstrates that the intelligent agent framework provides a powerful basis for addressing real-size open pit mine planning problems.

Jan 1, 2008