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By D Pateman, F de Fredrick

The Bentley underground mine, which is located 60km north of Leonora, Western Australia, is owned and operated by Round Oak Minerals Pty Limited. A high-grade Zn-Cu Volcanogenic Massive Sulphide (VMS) orebody, Bentley was discovered in 2008 with production commencing in 2012. Long-hole open stoping is employed to mine the steeply dipping ore body, and in recent years the Avoca method has been adopted. This requires all development in a particular area of the mine to be completed prior to stoping commencing in a bottom up sequence. Voids are commonly backfilled with loose Run-of-Mine (ROM) waste loose rockfill (LRF); or alternatively cemented rockfill (CRF) can be used. Stopes in the 3860 AOS and 3900 AOS panels were located below previously extracted Avoca zones, with LRF situated immediately above them. These high-grade stopes were originally designed with rib and sill pillars to maintain control of the existing backfill during extraction. Due to changing factors over time, including mining economics, alternative options to achieve full extraction of the stopes were reviewed, including: • Mining small successive full height stopes which would involve drawing a blanket of LRF down with the extracted ore (stoping under waste); • Stabilisation of the existing LRF above the stopes and implementing a primary/secondary stoping sequence, with the primary stopes backfilled using a cement fill. An assessment of these options was undertaken which determined that the second full extraction method was the most beneficial to the operation, and could be achieved using a cement grout (Minova’s FB200 grout) to stabilise the LRF in conjunction with implementing a sequence where the primary stopes would be backfilled with cemented aggregate fill (CAF). Footwall drives were developed adjacent to the rockfilled stopes, allowing for the installation of horizontal grouting conduits, as well as providing access to the top of the planned 3860 and 3900 level stopes for the placement of CAF. An interval at the base of the previously rockfilled stopes was grouted at multiple horizons to achieve the required thickness, with a comprehensive quality assurance/quality control (QA/QC) process undertaken. Primary stopes were CAF backfilled via an arrangement of downhole winzes, linking the top of primary stopes to cross-cuts developed off the associated footwall drives. CAF was delivered underground through an open reticulation network that was extended to the specific levels. Overall the successful implementation of the revised mining method effectively increased ore recovery while maintaining control of overbreak and dilution, providing significant financial upside. This was achieved while maintaining effective controls in light of the changes to the risk profile. Stabilisation of the existing rockfill has allowed the extraction of stopes to full height, including the originally designed sill pillars, representing an average 23% increase in ore tonnes on the initial design, with dilution from the stope crowns averaging less than 1%. The use of CAF in association with primary/secondary stoping, eliminating the need for rib pillars, has yielded an average 47% increase in ore tonnes compared to the base case mine design.

Mar 15, 2021

By Robert A. Jankowski, Charles A. Babbitt, Natesa I. Jayaraman

Today, approximately 31% of underground coal mining operations have designated occupations or areas with more stringent (below 2.0 mg/m3) respirable dust standards in place. Many U.S. coal mines have been able to maintain compliance with very low dust levels, and the Bureau of Mines, in an effort to identify those factors contributing to low dust levels, completed a survey of twelve continuous miner sections which were able to maintain their dust levels at or below 0.5 mg/m3. The quantity and quality of face ventilation appeared to be the most important factor in controlling dust exposure. The results directed Bureau research towards identifying improved face ventilation techniques for reducing quartz dust levels on continuous mining operations. This research has involved the evaluation of a half-curtain face ventilation technique which reduces the cross-sectional area of the entry, thus increasing the air velocity over the operator. The Bureau has also conducted extensive laboratory studies to compare tubing versus brattice, including an evaluation of both systems in a crosscut turn. In an effort to improve ventilation and reduce dust exposures of roof bolter operators working downwind of the continuous mining machine, the Bureau has evaluated two novel face ventilation systems. The first system consists of a fan discharge tubing technique which routes dusty air away from the return entry being bolted. In a technique similar to the fan/tubing concept, exhaust air from the upwind continuous miner face can be scrubbed using a dust collector to capture a portion of the dusty air, clean it, and supply it to the bolter operators as a split of clean intake air. A better understanding of face ventilation techniques should lead to solutions to the problem of more stringent dust standards due to quartz.

Jan 1, 1989

By D. M. Wade, F. F. Redfield

PRODUCTION at Aguilar started in 1936 and by 1942 the mine had reached a peak of 25,000 tons a month. Present production is only about 60 per cent of this capacity because of difficulties in railroad transportation and the rationing of fuel oil brought about by the war. In the early years, cut-and-fill stopes were tried, but square sets were found to be the most practical method in the southern section of the mine, where blocky, treacherous ground and greater mining widths are prevalent. Square sets and opencut mining were the rule until 1942, when it became increasingly difficult to get mine timber. The ore beds in the northern section of the mine were found amenable to cut-and-fill stoping as the rock was firmer and the veins narrower. At present 69 per cent of the ore comes from cut-and-fill stopes, 27 per cent from opencut, and only 4 per cent from square-set stopes. Massive galena and sphalerite with comparatively little quartzitic gangue constitutes the higher-grade ore. The gangue minerals that can be detected by eye in low-grade ore are rhodonite, wollastonite, and pyrrhotite. Wall rocks range from shale to quartzite, with occasionally a little limestone.

Jan 1, 1947

By T. Celik, B. Genc, C. Musingwini

"Mine planning software continues to be an important factor when it comes to the development of the South African mining industry. To contribute to this development, a new methodology to define and measure mine planning software utilization in the South African coal mining sector within an evolving data-set framework was developed. An initial data-set showing the mine planning software providers, their corresponding software solutions, as well as the software capabilities and information on the number of licences was collected and compiled in 2012 in an online database for software utilized in the South African mining industry. Details of the database development and implementation were published in the Journal of the Southern African Institute of Mining and Metallurgy in 2013. In 2014 the data-set was updated with additional and new information.In this paper, using the 2012 and 2014 time-stamps, a methodology for estimating the software utilization is developed. In this methodology, three variables: commodity, functionality, and time factor are used to define and measure the software utilization in order to ultimately inform decision making strategies for software utilization. Utilization in the coal sector was measured according to six different functionalities, namely Geological Data Management, Geological Modelling and Resource Estimation, Design and Layout, Scheduling, Financial Valuation and Optimization. The methodology is useful for stakeholders reviewing existing software combinations or intending to purchase new software in the near future and wanting to estimate the comparative attractiveness of a certain software package. These stakeholders include mining companies, consulting companies, educational institutions, and software providers. The work presented in this paper is part of a PhD research study in the School of Mining Engineering at the University of the Witwatersrand."

Jan 1, 2016

By T J. Sheer

Water vapour refrigeration (systems using water as the refrigerant) could potentially be used to provide chilled water at underground locations in mines, as an alternative to conventional refrigerators using refrigerants such as R-134a. The use of water as both the primary and secondary refrigerants is attractive in concept since direct-contact heat exchangers could be used, yielding higher coefficients of performance. The disadvantage of water is the very high specific volume of the vapour at low pressures, which leads to great challenges in compressor design, as has been reported previously in the context of slurry-ice plants for mine applications (Ophir and Koren, 1999). Steam ejectors have long been known as alternative compression devices for refrigerators, but no work has been done previously on the possibility of using ejectors powered by high-pressure water, which is readily available in mines from long pipe columns in vertical shafts. This paper presents the results of a laboratory investigation into the use of high-pressure water as the motive fluid in an ejector refrigerator. No previously reported liquid ejector system has achieved subcooling of the process fluid, ie a reduction in fluid temperature within the evaporator to a level below that of the motive fluid. In contrast, the present work demonstrated that subcooling could occur at motive water pressures above 5 MPa. Mine cooling applications were considered and it was concluded that while this concept would not be feasible as a mine-wide cooling source, there could be specialised applications where it would be beneficial. One application would be to cool backfill and thereby reduce the heat load at the working face. In this case the best performance would be achieved by using the ejector in combination with an energy recovery system such as a Pelton turbine or a three-chamber pipe feeder.

Jan 1, 2005

By I. M. Masters

Iron removal and control in processes employing pressure leaching technologies developed at Dynatec Corporation are reviewed. Discussions are focused on recent developments in the processing of nickel-copper matte and copper concentrates, and on the Ambatovy laterite project in Madagascar. Iron control and its implications on flowsheet design in the pressure acid leaching (PAL) treatment of laterite ores and in the oxidative pressure leaching of mixed nickel-cobalt sulphide intermediates are also discussed.

Jan 1, 2006

By P. Yu, L. X. Liu

"A mechanistic model for tumbling mills was developed during PhD studies at the JKMRC. The concept was presented at the IMPC of 2014, followed by progress in a sub-process of the model presented at the IMPC of 2016. Additionally, a number of papers on the sub-models and breakage function have been published. This paper provides a consolidated summary of the outcomes and status of the model. The overall model structure is presented along with the sub-models such as appearance functions, breakage rate functions, energy distribution, transport, and multicomponent grinding interaction model. The strengths and capabilities of the model structure as achieved to date are presented. The gaps in knowledge and sub-processes are also presented, providing a guide to the areas that require further research and development. It is proposed that the approach developed in this paper provides a structure that can accommodate future mechanistic, dynamic mill model evolution that can incorporate the latest research outcomes and provide a platform to test modelling improvements. This can assist in substantially improving the predictive mill modelling capability in the industry, the importance of which should not be underestimated for this workhorse of mineral processing.INTRODUCTION Grinding is almost the largest single energy-consuming process in the mineral processing industry, which was estimated that about 0.2% of global, and 1.3% of Australia’s electricity is consumed by comminution of gold and copper ores (Ballantyne and Powell, 2014). Although there are some relatively new grinding mills, such as stirred mills, vibrating mills and HPGRs (High-Pressure Grinding Rolls), etc., tumbling mills, as the traditional grinding facilities, are more extensively used."

Jan 1, 2018

By S. Kamalpour

It has been observed that the productivity of ferromanganese furnaces, and the stability of metal and slag compositions, vary considerably according to the type of coke used as reductant. However, the desired properties of coke for optimum furnace performance are not well understood. In this investigation, the behaviour of four cokes, which exhibited a wide range of performance in ferromanganese production, was investigated by means of laboratory simulations of reducing conditions in the furnace. The Stationary Charge in Controlled Environment (SCICE) technique was used to simulate the conditions in the furnace shaft. Batches of raw materials, mixed in the same proportions as used in practice, were heated at fixed rates to 900, 1100 and 1300°C then cooled. The mass loss was used as a measure of the degree of reduction. Conditions in the lower part of the furnace were simulated by means of melt-reduction experiments in which lumps of coke were drilled out to form crucibles in which enriched ferromanganese slags were reduced at 1500 and 1550°C then cooled. An examination of the raw materials and the cooled, reacted charges using a variety of analytical and characterization techniques enabled the sequence of reaction and changes in morphology of the raw materials to be followed. This enabled an understanding of the behaviour of the cokes during reduction to be developed, which was then used to explain the observed performance of the cokes in practice. By relating the observed behaviour of the cokes in the laboratory tests to measurable properties of the unreacted cokes and to their observed performance in practice, it was shown that to achieve high productivity and good furnace performance, cokes should be selected to have moderately high reactivity towards CO2 (Boudouard reactivity) relative to conventional iron blast furnace cokes.

Jan 1, 2004

CONTENTSIntroductionNorthern ExplorationDrive ConceptionGeneralDriving CrewDrive Cross Section and Track DetailsVentilation by Electrically Driven FanTemperatures and HumidityFan PerformanceRock Drill Carriage and Rock DrillsStandard Drilling RoundElectric Firing from Power MainsExplosives and DetonatorsCharging and FiringMechanical Loading and Electric HaulageOperating CycleStatisticalEquipmentAcknowledgementINTRODUCTION.The driving project described in :this paper is one of greater magnitude than usual for the Broken Hill field, and in the execution of the work a departure was made from long-established local practice by the introduction of mechanisation. The primary object of the drive is to provide sites for gaining information regarding the behaviour of the ore-bodies well beyond the limits of the present exposures.Due to thermal conditions, the major portion of the work was done on a six-hour shift basis, in contrast to the normal one of seven hours, with a five-day week.

Jan 1, 1946

Experience, it is said, is the best teacher. Some experiences, however, should be shared so that no one else will ever have to live through them again. The fire at the Sunshine Mine is one such experience. ?Hard-rock mines don?t burn.? The Sunshine Mine near Kellogg, ID, was the nation?s premier silver producer for many years. In 1972, the mine was nearly 6,000 feet deep, contained hundreds of miles of worked-out areas, and employed nearly 500 people. Because of its depth and the type of host rock for the silver (unburnable quartzite), the general thinking of the day was that fires in mines such as the Sunshine were impossible, because ?hard-rock mines don?t burn.? What wasn?t really considered was that timber supports, foam insulation, and mining equipment do burn and that the carbon monoxide gas produced by burning is far more deadly than fire itself. Thus, no one was prepared when, on May 2, 1972, a fire of un-known origin broke out below the 3100 level of the mine. Before long, 173 miners on the day shift were trapped by thick, black smoke. By the time the fire was out, 91 miners had died, and the Sunshine Mine Fire became known as one of the worst mine disasters of the 20th century. It became the catalyst for passage of the Metal/Nonmetal Health and Safety Act of 1977, which applied the same federal safety standards to hard-rock mines as those regulating coal. Mandated safety training, mine inspections, and equipment standards were brought into force.

Aug 1, 2002

By L W. Morley

The Division is concerned with physical methods as applied to geo-logical research and mapping. An at-tempt is made to describe long-term goals, illustrated by examples of projects in the fields of aeromagnetic interpretation, palaeomagnetic re-search, Pleistocene and groundwater geophysics, seismic surveying, electromagnetic research and instrument development. Cooperative projects in surveys and research, with universities, private companies and provincial organizations, are frequently undertaken. An outstanding example of this is the recently approved Federal-Provincial Aeromagnetic Survey Plan, the purpose of which is discussed both from an economic and a scientific point of view. HISTORY OF THE DIVISION M AGNETIC, electrical, seismic and gravity methods, as a means of extending the geologist's sphere of observation beyond the head of his hammer, came into wide-spread use for the first time after World ?war I. Interest in these methods was aroused amongst geologists of the Geological Survey and, in 1928, a group of these geologists and university

Jan 1, 1963

By William Brinkman, Mark Jolly, Nasim Soleimanian, Karl Dearn, Oliver Brinkman

"Glass manufacturing is a heat intensive process. There is a direct correlation between the batch distribution techniques and the furnace energy consumption, productivity, and quality of the glass manufactured. All four major segments (float, container, fibre, and specialty glasses) would benefit from using an optimised batch distribution technique where possible. Oscillating batch chargers (OBC) have been in use since the early 70s, despite their superior batch shape, coverage, and in turn positive effects on the energy consumption and productivity of the furnace they are almost exclusively used in container glass manufacturing. The OBC’s main difference compared with other charging methods is its ability to directly influence the batch initial velocity. This paper reports on results achieved in CFD models (GFM) used to study effect of the machine on the overall energy consumption in the doghouse and the melt space.IntroductionGlass manufacturing can be divided to four major segments float glass, container glass, fiberglass, and specialty glasses. The financial cost of manufacture, its impact on the environment, lack of standardisation and mounting pressure imposed by the authorities for reduction in emissions means that the industry and its suppliers are utilising CFD modelling in order to tackle these challenges. The need for high temperature to create and maintain the viscous flow, homogenisation of the glass melt, and maintenance of the process to allow continuous output of glass of the right quality are the contributors to the energy intensive activities that are involved in continuous glass manufacturing. This in turn has resulted in design of large container glass furnaces which have high energy consumption, low specific performance, and high CO2 emissions where the most efficient furnaces in the container glass sector have a specific primary energy consumption of 3.8 GJ /tonne of glass at a level of 50% cullet in the batch making even very small improvements in efficiency by operation optimisation a value adding activity [1-14].The theoretical calculated energy required to melt glass is 2 to 3 times less than the energy actually used to melt glass as a result of glass melt passing a zone 5 to 8 times before leaving the tank.[8]. This causes contamination as the result of mixing between the completely molten glass free from bubbles returning to the batch area where there is freshly molten non-homogeneous glass, still containing very large numbers of bubbles and un-molten batch. At high temperature some components are dissolved rather than melted. Given that an un-molten batch is a good thermal insulator, it can be transported a long way into the furnace, increasing the need for homogenization which also increases the glass residence time of glass melt. This is why large unbroken strings of batch should be avoided, as should an overall blanket without gaps."

Jan 1, 2014

By Frederick J. Pope

The protaxis of the North American continent consists, as is well known, of a large V-shaped area of Archæan rocks, which lie for the most part in the Dominion of Canada, and occupy an area of not less than 2,031,000 square miles. The western limit of this area extends from 'Lake Superior in a northwesterly direction to the Arctic Ocean, the southern is found along the Lower St. Lawrence as far as Labrador. A minor area, spoken of as the Adirondack region of northern New York, has a somewhat broken connection with the main body in a narrow band of igneous rock, which crosses the Upper St. Lawrence where it leaves Lake Ontario. The ancient crystallines are also presumably beneath all the later sediments, hut the above brief description outlines their principal exposures. This great rock-complex consists, for the most part, of a series of gneisses, which present great variations in both structure and composition. In certain sections areas of gneisses of the general composition of granite, and remarkably uniform in character, prevail. They consist largely, if not exclusively, of crystalline rocks in which a banding or foliation has been induced by pressure. These rocks constitute the basal member of the Laurentian system, and by later writers have been referred to as the Ottawa gneiss. In other and quite extended areas, gneisses, regarded by many as composed of altered sediments, are associated with crystalline limestones, quartzites, and much injected igneous matter. To this series the term Grenville has been applied. Both of these series of gneisses are penetrated by various igneous masses, of which the most important are great intrusioiis of several members of the gabbro family, such as anortho-sites, norites, pyroxenites, and gabbros proper; the whole form-

Jan 1, 1900

By Edward M. Kawenski

Float dust deposits in return airways in bituminous coal and lignite mines present a special explosion hazard. Research is in progress at the Bureau of Mines experimental coal mine to evaluate the degree of the hazard and to develop measures for preventing dissemination of dust into the ventilating air current. To determine the extent of this hazard prevailing in operating coal mines, 711 dust samples were collected in 50 mines located in the major coal fields of the United States. The mean quantity of coal and the incombustible content of the dust in the samples were determined. The term "float dust" is used to designate particles smaller than 74 microns in diameter (particles passing a No. 200 sieve) which have settled from the air current. Dust usually found in roadways and in working places is coarser than float dust, and is termed "coarse dust" (particles passing a No. 20 sieve). Variations in amount and incombustible content of coarse dust in a midwestern mine were studied previously.5

Jan 1, 1963

By Matti Kongas, Kari Saloheimo, Antti Remes

"The paper studies the control performance of the flotation process as a function of the measurement accuracy and sampling frequency of an on-stream XRF analyzer, using a simple dynamic model. An additional aim is to assess how the economical result of a mineral flotation process depends on the quality of process control based on the on-line elemental assays.An on-stream XRF analyzer measures the concentrations of slurry lines in a continuous cycle from several process points. The control performance depends on the analytical accuracy and sampling frequency of the concentration measurement. With a long cycle time, the state of the process changes before a new measurement becomes available. With short measurement times the statistical variance of the counted X-ray pulses increases, increasing the random error in the analysis. In addition, the measurement accuracy depends on the concentration of the component to be measured from the slurry.To quantify the effect of analysis error and frequency to process control, a simple dynamic process model is created in the Matlab environment. Data from a copper flotation circuit is used as a test case. The process model comprises a first order reaction equation and the grade-recovery -relationship estimated from process data. The control was modeled using the control strategies implemented into a rule based advanced control system.The economical performance of the control was studied by calculating the overall net smelter return at various analyzer parameter combinations. The economical performance of the process declines strongly when the sampling cycle is increased. In studied case the sample measurement time did not have a significant effect on the results. The economical performance of the simulated process corresponds to an almost uncontrolled process when sampling cycles longer than 40 min are applied."

Jan 1, 2003

By Theodore H. Eyde

In the southwest porphyry copper province, the virgin prospect with good copper mineralization cropping out has disappeared. Future discoveries will require an increasingly sophisticated arsenal of exploration techniques and concepts. One of the latter, stratigraphic analysis, is a technique which is often overlooked. A surprising number of exploration geologists still think of porphyry copper deposits as occurring wholly within intrusive bodies such as quartz monzonite or granodiorite. Disseminated copper mineralization, though genetically related to intrusive rocks, can occur within both the intrusive and the intruded rocks. At present, as much as 30% of the total copper produced from disseminated copper deposits in the Southwest originate from the intruded rocks rather than the intrusive.

Jan 4, 1972

By M. G. Zabetakis

This publication describes an investigation conducted by the Federal Bureau of Mines regarding the cause of an explosion of a dephlegmator or fractionating column at the Cities Service Oil Company Refinery, Ponca City, Okla., January 22, 1959. The column was that used with the refinery's No.1 Dubbs Coker. The explosion caused the death of an employee of the refinery and resulted in extensive damage to the refinery and to nearby property. The Bureau's study of the explosion began January 26.

Jan 1, 1960

By AIME AIME

THE week, of April 5 will long be remembered by those that attended the Birmingham meetings of the Open-Hearth and Blast Furnace committees of the A.I.M.E. Iron and Steel Division. Birmingham iron and steel own received the 450 delegates with open arms; described and discussed their southern metallurgical practices and problems and compared experiences with their northern brother metallurgists in two days of technical sessions on Wednes-

Jan 1, 1937

By Shaoxian Song, Shouci Lu, Jingyon Gou, Pan Yiuwen

The calculated potential energies of interaction between hydrophobic particle of three minerals (rhodochrosite, quartz and talc) and air bubble show that the energy of hydrophobic interaction is the dominant factor for their attachment. An attachment rate equation, integrating particle -bubble collision and adhesion by introducing a "capture efficiency", has been put forward. It was found that the hydrophobic particle-bubble aggregates can not be disconnected in the bulk zone of flotation cell, whereas in the impeller zone the breakup may occur, particularly for the coarser particles captured by bubble. Finally, the flotation rate constant was estimated theoretically and verified by experiments.

Jan 1, 1995

By W. Dziurzynski

The present article sets forward the results of field tests that made it possible to validate the mathematical model used in the VENTGRAPH ventilation engineer programmes. The case considered relates to the introduction of a new heading to the ventilation network of the mine. The utilisation of computer programmes in practice is justified by the necessity of ensuring expected performance and secure conditions in the network of mine headings, where - for example - plans are being made to utilise the transport dip-heading, taking into consideration fire and methane hazards. In the article we have presented the methodology of preparation of a database for computer programmes of the VENTGRAPH system, obtained on the basis of ventilation measurements. The next step consists in the execution of a design of the modified network and prediction, this on the basis of heading geometries, of parameters characterising the flow of air for the designed headings. Due to the fact that the heading was in the final stage of driving, following its introduction to normal operation and the stabilisation of flow values it was possible to retake ventilation measurements, which validated the results obtained through computer simulations. In order to execute measurements of the volume flow in the dip-heading, we employed a new wireless multipoint measurement system to determine the velocity field of air in the mine heading; the results are characterised by a high accuracy of measurement. As a part of fire prevention and incident management planning, a series of underground fire case studies for the a validated network flow model has been made. Results of simulations show the capabilities of the FIRE module of the mentioned software, including assessment of stability of flow directions and hints on counter and preventive measures for particular locations of fire.

Jan 1, 2009