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By Thomas J. Peters

In 1985, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied a 17,320-acre portion of the 52,143-acre Little High Rock Canyon Wilderness Study Area (CA-020-913/NV-020-008) in order to evaluate its identified mineral resources. The study area is located in Humboldt and Washoe Counties, NV, about 42 miles north from Gerlach. Three areas of epithermal alteration, similar to alteration associated with disseminated gold deposits, were found in the study area. One of the areas occurs along a northeast-trending structural lineament. Southwest of the study area two gold prospects undergoing active exploration, as well JS a gold deposit being prepared for production, occur along the same lineament. The Bureau of Mines examination, however, did not find evidence for gold resources in the study area.

Jan 1, 1987

By J. Yue

"Mount Milligan mine is located in northern British Columbia. The concentrator employs conventional SABC grinding circuit with bulk sulphide flotation processes. Commissioning started in September of 2013 and nameplate production of 60,000 TPD was reached in the fourth quarter of 2015. As is typical with many mill ramp ups, bottlenecks developed as throughput increased. Since then, plant modifications and new control philosophies in the comminution and flotation circuits have been implemented and evaluated. The mine-to-mill collaboration played a key role in reaching target throughput rates by improving blast fragmentation and implementing temporary pre-crushing. Results of the projects as well as ongoing challenges/bottlenecks and solutions will be discussed.IntroductionMount Milligan Mine is a copper-gold producer located approximately 253 km northwest of Prince George in British Columbia. Production commenced in September 2013 and reached nameplate capacity of 60,000 TPD in December 2015. Average head grades for the mine life average 0.18% Cu and 0.39 g/t Au.Circuit DesignOriginal process design began with run-of-mine ore from the pit crushed through a 60-110 gyratory crusher, conveyed to a live ore stockpile and fed to the mill via four variable apron feeders. The concentrator circuit employs SAG mill - Ball mill - Pebble Crusher (SABC) grinding configuration to grind the ore down to a target P80 of ~200µm. It is then fed to two parallel trains of flotation tanks, each consisting of five 200 m3 tank cells with the first two being roughers and last three being scavengers. Concentrate streams from roughers and scavengers are separately reground with a closed circuit Tower mill and two open circuit ISA mills operating in parallel, respectively.Three stages of cleaners upgrade roughers/scavenger products to 25% Cu followed by a cleaner scavenger stage. The final concentrate is then thickened and filtered to approximately 9% moisture and shipped off site (Figure 1)."

Jan 1, 2017

By N F. Fraser

Seafield ResourcesÆ offshore placer gold project covers c.10 000 km2 of the Westland continental shelf between Karamea and Jacksons Head, from the low-water mark out to the 120 m isobath (Figure 1). De Beers Marine (DBM), the marine diamond subsidiary of the De Beers Group, will carry out the project with geological input from Placer Solutions (PSL). DBM bring a wealth of expertise and advanced technology to the project, developed during their 20 years of exploration and mining of diamond placers on the Atlantic shelf of southern Africa, where they have also maintained a strong environmental record.   Glaciers and high-energy rivers emanating from the Southern Alps have transported substantial quantities of gold bearing sediment onto the Westland continental shelf during Pleistocene glacial periods, when fluvial gradients are steeper, sea level is c.120 m lower and most of the shelf is exposed. These deposits have been extensively reworked by the advancing shoreline and marine processes during interglacial marine transgressions, and most are now buried beneath a variable thickness of post-glacial marine sand, silt and mud. DBM will use side-scan sonar, swath bathymetry, Chirp sub-bottom profiling and a magnetometer to map the sea floor and sediments beneath it, guided by PSLÆs predictive geological model for gold distribution on the shelf. Cactus grab and vibro-core samples will be used to ground-truth the geophysics and provide stratigraphic, sedimentological and gold distribution data for incorporation into the geological model. Areas of interest identified by the geophysical and sampling data will be investigated in more detail, with closer-spaced geophysics and Mega-drill sampling to a maximum sediment depth of 20 m beneath the sea floor. These samples will be raised to the ship with air-lift suction technology, processed onboard for mineralogical and grade information, then returned to the sea floor. Environmental baseline data will be gathered from Van Veen grab samples of seabed sediment taken throughout the area during the prospecting programme.

Jan 1, 2005

By R. P. Harvey, J. E. Walstrom, A. A. Brown

In view of the large number of wells directionally drilled from offshore platforms and urban drillsites, greater interest is being focused on the directional survey and on the uncertainty inherent in calculating the position of the bottom of the hole, or other benchmarks in the wellbore. Of the two methods presented here for evaluating this uncertainty, the first is analytical and uses the principles of probability and statistics. The second method uses Monte Carlo simulation to generate a pattern of the scatter of possible bottom-hole locations. Both methods are based on a model for which the usual assumption is made that the curvilinear axis of the wellbore is adequately represented by a large number, M, of linear segments joined end to end from the top to the bottom of the hole and closely following the course of the hole. The errors due to this approximation are assumed to be negligible and are not studied here. One form of the model is to consider that for a given hole there exists a perfect set of data describing it, of the above form. Each linear segment has an angle of inclination with the vertical 7, in radians, an azimuthal angle from true north xi in radians, and a length Si, in feet. The subscript variable, i, extends from 1 to M. Each of the M linear segments representing the axis of the wellbore has three components in the X, Y, and Z directions. These components are calculated from the equations: The bottom-hole coordinates as determined from the reference set of data for the wellbore are given by the following for i = 1 to M: X=SX, Y = Sy, Z=SZ; . (2) A directional survey instrument, lowered into the wellbore to the M segments, or stations, measures the values of the 7; and the 3,. In general, because of errors from various sources, the resulting angular measurements will not be precisely equal to the 7" and xi. Random variables l, and Ai are therefore considered with associated probability density functions fi(li) and gi(Ai), respectively, which represent the distributions of potential survey measurements for this hole. Since it is assumed that the values Si are accurately measured they are treated deterministically. The random variables corresponding to the surveyed bottom-hole coordinates are given, for i = 1 to M, by:

Jan 1, 1970

By Juliana Mesquita de Andrade

Em sistemas cerâmicos policristalinos as homojunções e heterojunções podem apresentar comportamento elétrico desde completamente ôhmico até com elevada característica retificadora, que no limite é a base do comportamento varistor, o qual é o dispositivo de proteção de sistemas e equipamentos eletro-eletrônicos contra sobretensões mais utilizado. Os óxidos de zinco (ZnO) e de estanho (SnO2) são, individualmente, base dos varistores com melhores comportamentos elétricos. Este trabalho, com base nas caracterizações estruturais por técnicas de microscopia eletrônica de varredura e análises termodilatométricas, e na caracterização elétrica e dielétrica, avalia as propriedades varistoras de cerâmicas à base do sistema misto ZnO-SnO2. Verifica-se a formação de um sistema polifásico apresentando homojunções e heterojunções com diferentes características morfológicas e graus de densificação, exibindo ainda comportamento eletrotérmico com predomínio de características varistoras em função da dopagem da matriz mista ZnO-SnO2. Os resultados obtidos evidenciam a tendência da formação de espinélio (Zn2SnO4) em presença de grãos de SnO2 e do estabelecimento de comportamento varistor (coeficiente de não-linearidade > 10), que pode ser aperfeiçoado por dopagem adicional e por tratamentos térmicos, principalmente quanto à redução da corrente de fuga e da ampliação e estabilização da região não-linear da curva tensão x corrente elétrica.

Aug 7, 2018

By W. B. Collingwood, D. Misra, T. Ghosh, S. Bandopadhyay

Understanding the variability of sulfur and calorific value in coal seams is critical to planning mining operations and marketing the mined coal. In this study, statistical and geostatistical techniques were used to explore the underlying spatial trends present in a large coal deposit. Eight prediction models for the sulfur content of the coal seam were developed. Six of the models were created using geostatistical techniques, while the remaining two models were created using other techniques. The performance of each model was examined by conducting cross validation exercises. The results of the study showed that very pronounced trends and anisotropies were present in the sample data, which had to be accounted for in the modeling. The study found that a cokriging model using sulfur and ash is the best prediction model for predicting sulfur content in this coal reserve.

Jan 1, 2014

By B. J. Elliot

The Outokumpu Oy flash smelting furnace was designed for a capacity of 69,5 mtph of concentrate. The history of developments on the flash furnace, from the original operating capacity of 55 mtph to a proven capacity of 115 mtph of concentrate, is summarised. The new feature of operation at BCL Limited is ?the use of screened lump coal reduction in the settler region of the furnace. This paper considers the effects of settler bath reduction on the furnace smelting capacity, the condition of the furnace ?lining and bath, and ,the slag losses generated from the flash furnace and ultimately to discard. By using the settler bath reduction technique the capacity of the furnace for smelting new concentrate has been increased by 15% and hearth accretion has been eliminated by direct reduction with coal, which has also allowed the generation of a substantial protective lining on the furnace walls and roofs. As a result of improved slag losses from lump coal charging the metal recoveries on the flash furnace have increased from 70% to 87% for nickel, 68% to 82% for copper, and 28% to 45% for cobalt.

Jan 1, 1983

By J L. Lett, I Brunton, T Thornhill

Block cave fragmentation has been documented in the literature to have a significant impact on mine design, performance and downstream material handling and comminution processes. Due to this impact, emphasis is placed on the premining prediction and subsequent quantification of primary and secondary fragmentation distribution. This paper discusses the fragmentation prediction and assessment methodology employed at the Ridgeway Deeps (RWD) and Cadia East PC1 (CEPC1) cave operations.Prediction of drawpoint fragmentation was based on an iterative process, which relied on an improved quantitative and qualitative understanding of the rock mass as the mining project developed. In particular, the collection of scanline mapping data provided detailed information in relation to discontinuity trace length, persistence, termination characteristics and large-scale planarity. This allowed an improved estimation of select modelling input parameters, in particular ‘block forming’ discontinuity orientation and strength characteristics.With the start of production, drawpoint fragmentation assessment was undertaken using digital image processing (DIP) techniques for drawpoint extracted tonnes up to 61 000 t. This technique provided a consistent methodology to estimate changes in fragmentation as the block cave matured. It can generally be concluded that the measured mean fragmentation distribution became finer as drawpoint tonnage increased. The incremental change in fragmentation distribution (per 10 000 t) was not uniform, with step changes evident. In addition, for a given geotechnical domain and drawpoint tonnage, the measured fragmentation distribution range was found to vary significantly. A possible explanation for these observations may relate to the disturbed flow behaviour noted from marker experiments at RWD and CEPC1. These experiments indicate that material reporting at the drawpoints (for any given tonnage extracted) may be sourced from highly variable heights within the cave, with finer material preferentially reporting.A comparison between predicted and measured drawpoint fragmentation distribution indicated two general findingsa close match between predicted and measured distributions for material greater than 1.0 m3an under prediction of finer material passing 0.5 m3 relative to measured.The findings would indicate that the fragmentation modelling frameworks utilised at both RWD and CEPC1 were deficient at predicting the percentage of finer material for both primary and secondary fragmentation.The wide range in fragmentation distributions observed in the measured results, and the discrepancy between modelled and measured fines should be considered in the design of mine (material flow, extraction level geometry and draw rate), material handling (crushing and material movement), and downstream milling (comminution and metal recovery) processes for future block cave mines at the Cadia Valley Operations (CVO). With respect to fragmentation distribution range, a sensitivity analysis should be undertaken for these design considerations, with a range in predicted fragmentation distributions investigated (for example, lower quartile, mean and upper quartile). For future mines with similar geotechnical and mining conditions, the calibration of fines should be considered in any fragmentation distribution prediction to match those measured previously.CITATION:Brunton, I, Lett, J L and Thornhill, T, 2016. Fragmentation prediction and assessment at the Ridgeway Deeps and Cadia East cave operations, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 151–160 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By H. S. Price

This report discusses the development of a mathematical model that describes the flow of methane only and methane and water in a coal bed during mining operations. Because of the complex geometry, boundary conditions and fluid properties, the model is based on a numerical solution to the equations describing flow. The goals for the development of this model and requirements to which it complies are for the most part expressly stated in Request for Proposal No. 50110752. In addition to the capabilities specified under the scope of work the model can handle an anisotropic porous medium and a source term has been added which will simulate, somewhat, the effects of desorption. This term will be pressure dependent. The effect of time on such a term is only taken care of in the change of pressure with time. This source term will have the dimensions of Mcf/day/Mcf pore volume. It will be a part of the input data to be supplied by the user and will be entered as a table of rates versus pressure. These models consider the fracture system as the main porosity. All computed results pertain to the fractures. The source term mentioned above represents the flow from the matrix porosity into the fracture. Such flow should be small compared with the flow between fractures since these models handle only one porosity structure system.

Jan 1, 2012

By Tainan Ferreira Muniz

Visando atender à demanda de materiais de engenharia que apresentem elevada resistência ao desgaste sem prejudicar sua ductilidade, o presente artigo objetivou avaliar a influência dos tempos de cementação em meio sólido nas propriedades mecânicas de um aço baixo carbono submetido ao tratamento. Adotou-se diferentes tempos de estágio, a saber 6h, 11h e 24h, fixando-se a temperatura a 900ºC. Além disso, a fim de verificar a validade dos experimentos e compará-los às previsões teóricas, estimou-se, pela Lei de Fick, a profundidade da camada cementada. Métodos mais práticos, como a elaboração de perfis de dureza e a análise de microestruturas, reafirmaram as previsões e indicaram que a profundidade da camada cementada aumenta com o tempo de exposição das amostras à atmosfera adequada.

Oct 30, 2017

By J. C. Loretto

"OPENING REMARKS Yesterday and today we have heard some very interesting papers on operating matters and some of you are probably wondering what we are now doing talking about Communications in Plant Design. Let me tell you! Before the techniques we have heard being discussed can be used, there has to be a properly operating plant. It is certainly a fact that many mineral processing plants achieve only limited success and a number of them can even be said to be failures. Some of you sitting here are probably living with operating problems that are clue to errors in the design.If the histories of these problem plants are examined, it will be found that in many cases, the necessary skills were available during the period of the plant design. There was extensive operating know¬ledge together with a full range of project expertise. Why then the failures? In a substantial number of cases it can be traced to the old, old problem of communications. As plants get bigger, money costs more and smooth startups become more important, it becomes less and less economic to fix up any design errors during plant operations.During our careers in mineral processing, nearly all of us will be involved in at least one plant design and I feel that it is as well if we understand some of these communication difficulties that can lead to a problem plant. There is little point in us being experts in mineral processing if the knowledge we have acquired doesn't somehow get incorporated into the plant.I would, therefore, like to present this short paper that mentions a few of the significant communication problems that can occur during the design of mining and mineral processing plants, together with some thoughts on answers to these problems."

Jan 1, 1973

By Michael J. Lawrence

"The VALMIN Code was developed and formally adopted by The Australasian Institute of Mining and Metallurgy (AusIMM) in 1995 and a revision was issued in 1998. The VALMIN Code applies to all relevant reports under the Australian Corporations Law, including submissions to the Australian Stock Exchange (ASX) and the Australian Securities and Investments Commission (ASIC).The VALMIN Code and Guidelines sets standards for the preparation and commissioning of independent assessment and/or valuation reports on mineral and petroleum assets or mineral and petroleum securities.It is mandatory for AusllvI:M's members to follow this Code in these relevant circumstances and failure to do so will result in serious sanction of the member by the Ausllvllvfs Ethics Committee. Public support for the use of this Code has been given by regulators (ASX/ASIC) and market participants ( eg major accountancy firms). It is also endorsed as a guide to general best practice in project assessment and valuation.This paper will discuss how the VALMIN Code has worked in practice over the past few years. It will also examine areas where the Code could be improved and how it could form the basis of a new Canadian Code for mineral property valuation."

Jan 1, 2003

By P. Lafleur

All indications point to a growing market for thermal coal in Japan as part of the country's current energy policy formulation process. The Ministry of International Trade and Industry forecasts imports of 16 million tons a year in 1985 and 40 million tons in 1990-a twenty-fold and forty-fold increase over the present level. This potential reflects Japan's over-all serious and increasing concern for security of energy supplies and its resultant need to seek alternative sources. Nuclear power will be the main alternative source, but, because it is expected that its development will be slow, imported thermal coal will assume greater importance. Canada, with large resources of all types of coal, could fill a portion of this market. Thermal coal could come from specific thermal coal developments or from metallurgical coal mines, which usually produce a certain amount of coal not amenable to coking, but suitable for power purposes. However, penetration of this Japanese market by Canadian thermal coal will depend on the resolution of a number of problems. On the demand side, siting, environmental aspects, the need for a coal unloading and trans-shipment centre, and the added cost of installing coal-fired stations could be major constraints. Although Canada has ample high-quality resources, any new development tied to the Japanese market will require improvement in prices to cover the high costs associated with transportation, the construction of new mines and the provision of new infrastructure.

Jan 1, 1979

By Brosnan J. G

Simcoa Operations is the only silicon smelter in the region and since the plant was commissioned in late-1989, has progressed from supplying silicon metal to the secondary aluminium market to the current position of supplying in excess of 90 per cent of its production to the high quality chemical and primary aluminium markets. This position has been achieved through the unique advantage which Simcoa has developed within the industry, namely raw materials, people and Simcoa's ability to adopt and use modern technology. A quality culture was instilled into the workforce prior to commissioning which ultimately led to AS3902 qualification in 1992. Simcoa has continued its quality drive through the formation of 'Simcoa's Quality Leadership Process' which is planned to make Simcoa the best silicon producer in the world.

Jan 1, 1995

By George Filz, Peter R. Cali

"Unnecessarily restrictive specifications could be limiting the cost effectiveness of deep mixing (DM) applications and therefore limiting use of DM on projects where there are other options. Excessively restrictive standards demanded for strength and permeability certainly increase contractors’ bid prices, and costing the owners and, in the case of Government projects, the taxpayers more than necessary. Yet, lax or ineffective specifications often exist for some vital components of the quality assurance and quality control. In this paper, specifications for key elements of DM design and construction are examined. Recommendations are made to improve and streamline DM specifications to better serve the common objective of constructing a safe and cost effective ground improvement project.INTRODUCTIONSpecifications should, at their best, convey the project design requirements and provide clear direction to the contractor regarding requirements for submittals, materials, execution, measurement, schedule, and other aspects as necessary. The specifications should not be overly conservative, restrictive or ambiguous, and they absolutely should not be deficient in measurement of quality. Guide specifications or recycled sections from previous projects often form the template for new project specifications. But standards that appear in guide specifications or from former successful construction should be critically scrutinized by the designer for relevance before using the copy/paste functions of the specifications writer’s keyboard. Because work does not always go as smoothly as planned, specifications for remediation of non-compliant construction should be clearly stated and enforced. Often, non-compliancy is reviewed after-the-fact and deemed to have met the design intent, indicating that either the specifications were too restrictive or the enforcement too weak.The Federal Highway Administration Design Manual: Deep Mixing for Embankment and Foundation Support, October 2013, was written by a panel of DM expert design practitioners and contractors. Guide specifications are included as Appendix C of the FHWA manual. Those guide specifications have been updated in the deep mixing section of the www.GeoTechTools.org website, and the updated specifications represent the most complete and authoritative compilation published to date. Although the specifications for DM at www.GeoTechTools.org are current and complete, and they portray the state-ofthe- practice, they too must be modified to fit specific DM applications, project needs, and site conditions. The keys to a good set of specifications are to prescribe construction only to the level that is required to meet the design intent, to require appropriate quality control and quality assurance (QC/ QA) activities, and to clearly address remedial measures required for non-compliant work."

Jan 1, 2015

By Larry Joe Linley

The Department of the Interior, Bureau of Mines is reviewing explosion protection methods for use in gassy coal mines. This performance criteria guideline is an evaluation of three explosion protection methods of machines electrically powered with voltages up to 15 000 volts AC. A sufficient amount of basic research has been accomplished to verify that the explosion-proof and pressurized enclosure methods can provide adequate explosion protection with the present state of the art up to 15 000 volts AC. The routine application of the potted enclosure as a stand alone protection method requires further investigation or development in order to clarify performance criteria and verification-certification requirements. An extensive literature search, a series of high voltage tests, and a design evaluation of the three explosion protection methods performed at White Sands Test Facility indicates that the explosion-proof, pressurized, and potted enclosures can all be used to enclose up to 15 000 volts AC, if the performance criteria and verification-certification requirements recommended in this guideline are implemented.

Jan 1, 1982

These proceedings consist of an introduction, nine descriptive papers, and a summary. The first paper is an overview of the respirable dust research program, the second paper describes the Mining Enforcement and Safety Administration's proposed changes in the respirable dust enforcement program, and the third paper describes respirable dust measurement. The remaining papers, by Bureau and contractor personnel, describes methods of reducing the amount of respirable dust to which coal miners are exposed. Of the six methods of reducing exposure to respirable dust described, two are methods of preventing or reducing the amount of respirable dust raised during mining operations, two are methods of collecting or removing dust after it has been released into the mine atmosphere, 2nd two describe methods that are combinations of prevention and collecting .

Jan 1, 1977

By R Stefansen

Stockyard operations are governed by the interaction between the different disciplines required to successfully schedule and control the supply chain of raw material through the stockyard in combination with the effectivity of the operation of the stockyard equipment. The system demonstrates a proven technology for implementing a centralised operation of full unmanned stockyard equipment, using a high precision absolute positioning system based on a Real-Time Kinematic (RTK) Global Navigation Satellite System (GNSS) receivers in combination with 3D rangefinders. The system implementation maps the surface profile of the stockyard inventory and allows in combination with proprietary algorithms for full operation of the stockyard machines without on-board operators. The operational impact of delayering the process by moving to a centralised operation is examined, together with the combined effect on the overall safety in the stockyard as a result of a change in reliance on operator skill dependencies. Average performance gains range from 10–20 per cent. The performance of the automation system is related to a consistency and reliability of uniform operation, which has an impact on the life expectancy and the effectiveness of the equipment. The effects of having instantaneous and correct information about the stockyard inventory volume measurement are investigated in relation towards spot price trading in current fast reacting markets.CITATION:Stefansen, R, 2017. Advanced automation for centralised stockyard operations, in Proceedings Iron Ore 2017, pp 105–110 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Brian E. McGee

The Federal Coal Management Program represents the culmination of several years of effort by the Department of the Interior (001) to reformulate the manner in which coal owned by the United States is leased and developed. These efforts began in 1970 with a study by the Bureau of Land Management (BLM), which indicated that unless drastic changes were made in. the federal coal leasing procedures, federal coal lands would be leased almost for the asking while production of coal from those lands had been decreasing. Consequently, informal action was taken in 1971, which resulted in no further leasing being authorized until February, 1973. At that time, a formal moratorium on most coal leasing was established, with exceptions granted only for leases needed to satisfy short-term needs such as maintaining existing mines or supplying reserves for new contracts in the immediate future. This leasing policy embodied a long term objective of developing an entirely new planning system for federal coal leasing, as well as to schedule the preparation of a programmatic impact statement for this new system. As a result of the 1973 moratorium and the ensuing application of short-term criteria, only 10 federal coal leases (covering approximately 30,177 acres) were issued from February, 1973, through January l, 1976.

Jan 1, 1982

By J. Rothschild

I would like to thank the Society of Mining Engineers for inviting me as well as the other distinguished panelists to spend a morning reviewing and discussing the handling and shipping of industrial minerals. I also would like to thank my management, Cometals. Inc. for permitting me to take time out from the daily hectic pace of marketing and trading to share with you some of our experiences and expertise. Cometals, Inc. is a wholly-owned subsidiary of Commercial Metals of Dallas. The transportation and handling costs of industrial minerals frequently are a major component of the value of the goods marketed and, therefore, it is only natural that close attention should be paid to them. Many of the industrial minerals require special handling to assure that the material reaches the consumer without being contaminated or getting wet. I invite you to accompany me through the various steps involved in "delivering the goods" to the consumer.

Jan 1, 1989