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Anglo Platinum commenced commercial underground borehole radar (BHR) surveys during 2006 following a series of trial surveys using both the ?slimline? Geomole and Aardwolf systems. Current borehole radar systems comprise radio frequency transmitter ? receiver antennae operating at 30 -100MHz that measure the time taken for a transmitted pulse to traverse a rock volume and be received (Fig 1). The time taken can be converted to distance if the transmission speed of the pulse through the rock volume is known. The transmitted pulse may be reflected off a suitably orientated geological reflector (in reflection mode) or may be recorded in receivers located in other boreholes (cross-hole tomographic mode). In the Bushveld Complex lithologies, these radar systems have ranges of 30-50 metres in reflection mode depending on the electrical properties of local stratigraphic units. Both the Merensky Reef (MR) and the underlying UG2 have been shown to act as reflectors, which offer the opportunity of using BHR as an imaging or mapping tool. Reflection of the radar signal occurs wherever a strong contrast in dielectric constants occurs such as between norite and harzburgite or where chromitite stringers are present. [ ] Fig 1 Main elements of a borehole radar system Much experience has been gained in the practical application of BHR surveys in platinum mining. The value of a BHR survey is that it provides a continuous line of information to ?connect the dots? rather than a few discrete pierce points. BHR surveys can be used to mitigate risk in three crucial areas: ? Mine planning at the strategic as well as tactical level ? geotechnical evaluation of proposed shaft sites, detailed profiling or mapping of reef and disruptions of the reef such as faults, rolls and potholes; ? Mineral resource classification ? identification of structural discontinuities in orebodies affecting resource classification e.g. potholes and reef facies; ? Safety ? identifying areas with poor ground conditions that are often associated with faults, dykes and potholes.

Jan 1, 2007

By Patrick J. Cain

The fatigue-failure characteristics under high-frequency (10 KHz) cyclic loading were determined for a marble, granite, and quartzite. The rock speci-mens were cyclicly loaded (using a high-power piezoelectric sonic transducer) at a constant strain amplitude generated by forming a longitudinal standing stress (strain) wave in the cylindrical test specimen. The number of load cycles required to fail each rock type at a given strain amplitude was deter-mined. The fatigue fractures were tensile in nature and the fracture load amplitudes were as low as 30 pct of the static tensile strength. Also the internal heating of the rock caused by the material damping (internal friction) was measured. The damping and internal heat generation in the specimens was analyzed to show that nearly all of the power input can be accounted for as a change in enthalpy in the specimen. Using these results the thermal strain in the rock was calculated to evaluate its contribution to fatigue failure. The thermal strain was found to range up to 30 pct of the dynamic strain amplitude depending on the load amplitude and the number of load cycles. The specific energy required for failure was determined and possible applications of the high-frequency fatigue fragmentation process are discussed.

Jan 1, 1975

Interest in industrial minerals in recent years has increased to such an extent that it has taken them into the mainstream of the Australian mineral industry. Notwithstanding that time series data on the values of production, exports, and imports show that industrial minerals are overshadowed by metals and energy minerals, their contribution to the national economy is important and more significant than would seem to be indicated by the statistics. Whereas the ex mine value of metals generally includes some processing (at least to a concentrate stage), most industrial minerals are valued at little more than their extraction cost, in addition to which such costs are generally low because most industrial minerals are exploited in low-cost surface operations. Consequently, values of mine production of metals and industrial minerals are not strictly comparable in that values of mine production of metals tend to be overstated Short term growth of the industrial minerals sector is assured because of several new projects already commissioned but not yet reflected in the statistics. Longer term growth is also assured, based on various other major projects that are likely to come on stream in the early to mid 1990s.

Jan 1, 1989

By E. L. Rawlins

Systematic leakage surveys of natural-gas transmission lines not only aid in the conservation of gas, but can be made to show direct financial returns of large magnitude. 1. Such surveys reveal the actual leakage from the lines, and indicate repairs to be made in order, to eliminate unnecessary waste. 2. Tests on lines, after repairs are made, show the actual saving that has been accomplished. 3. Tests on newly constructed lines reveal the presence of leakage that should be eliminated before the lines are put into service.

Jan 1, 1926

By Steinar L. Ellefmo, Fredrik Søreide

"The Norwegian University of Science and Technology (NTNU) and Nordic Ocean Resources AS, with support from Statoil ASA have carried out a project reviewing the knowledge about seabed mineral resources in Norway to identify and prioritize needs for further research and development.A special focus area in the project has been to increase the knowledge of possible massive sulfide mineralizations along the Mid-Atlantic Ridge. This Ridge is a subsea mountain range which separates the Eurasian and the North American continental plates. In this area, seafloor massive sulphides (SMS) are formed from the volcanic and hydrothermal activities along the Ridge. A large part of the North-Atlantic Mid-Atlantic Ridge between Jan Mayen and Spitsbergen is located on the Norwegian shelf.Analysis and interpretations of multibeam data have been carried out by NTNU in cooperation with the Russian Institute for Geology and Mineral Resources of the Oceans in order to disclose relevant areas for the formation of SMS deposits. This analysis has identified several promising areas."

Sep 1, 2014

By J. Hansen

"ABSTRACTThe paper addresses the application of automated monitoring, control, and navigation to improve dragline performance. SummaryImproving dragline performance in the Canadian coal mines is critical to the continued success of the industry. Draglines represent a large capital investment and coal prices are low by historic standards. This paper argues that the introduction of monitoring, control, and navigation on draglines offers an opportunity to significantly reduce a dragline’s operating cost per cubic metre moved. To place the importance of this in perspective, a North Dakota mine calculates that every 1% increase in dragline productivity means a savings to the mine of US$340,000 per year. MonitorsAutomated dragline monitoring is a well established technology with commercial products available since the early 1980s. The three main reasons for placing monitors on draglines are (Walker, 1993):1. productivity increases: reduce variations between different operators’ performance across different shifts;2. quality increases: increase the percentage of ore and waste loads that go to the correct destination; and3. special projects (engineering projects): justify installing static field exciters and regulator upgrades; implement power management; aid operator training; study high performance buckets, rigging changes, and various excavation sequences.Mines as diverse as Kennecott’s Cordero- Rojo Complex in the United States and Natal Coal Corp.’s Optimum Mine in South Africa report dragline productivity increases of 10% to 20% in the region attributed to the implementation of dragline monitoring."

Jan 1, 2000

By D Mnller, J L. Mauk

The Oblaga Cu-Au skarn deposit and porphyry prospect is located in the south-eastern edge of the Gobi Desert in western Inner Mongolia. The deposit occurs within metamorphosed middle Paleozoic volcanic, plutonic and sedimentary rocks.   Ivanhoe geologists recognise eight main rock types in the area. Calcareous sediments include conglomerate, interlayered siltstone-sandstone, and limestone. Covering the calcareous sediments is a slab of thrusted biotite granite, and above it is rhyodacitic lithic tuff which, in places, is overlain by alluvial sediments. Various plutonic rocks and related intrusion breccias have intruded these units. Monzodiorite, quartz-monzonite and monzonite tend to form thin, high-angle intrusions and the youngest andesitic intrusions are generally wider and subhorizontal.   The Oblaga Cu-Au skarn, which occurs in the calcareous sediments, shows typical prograde and retrograde mineralogy. Petrographic studies show that prograde skarn minerals have been overprinted by retrograde skarn minerals, and original host rock minerals have been texturally obliterated and completely replaced. The mineralogy of the Oblaga skarn deposit is very similar to other Cu-Au skarn deposits worldwide.   Sericitic and minor chloritic alteration occurs throughout the study area and may relate to porphyry-style mineralisation. Generally, this alteration is not intense and most rocks have retained their original texture. Geochemical analyses suggest that K-metasomatism is not widespread at Oblaga. XRD analyses suggest an upward and outward transition from sericitic to chloritic alteration.   Comparisons between Oblaga and other porphyry Cu-Au deposits worldwide show that Oblaga has very similar characteristics to deposits that have undergone sericitic alteration. However, Oblaga is special because it also has relatively intense chloritic alteration, which is uncommon in other porphyry Cu deposits described in the literature.

Jan 1, 2005

By Roy C. Bartholomae

This Bureau of Mines report presents the results of a laboratory investigation of coal cutting mechanics and noise. These experiments were performed using linear cutting apparatus that operates over a broad cutting speed range. The influence of several coal cutting parameters on the noise, force, productivity, and specific energy associated with linear cuts was ascertained. Some basic theoretical aspects of coal cutting mechanics and noise generation are discussed, and the results of the laboratory experiments are used to formulate analytical models of the coal cutting forces and noise. The analytical model for coal cutting noise is then generalized to account for the more important effects of rotary cutting. Based on the generalized model, an estimate of the sound pressure level at an operator's position is made for a typical continuous mining machine. It is concluded that by employing linear rather than rotary cuts, using deeper depths of cut, slower cutting speeds, and more efficient cutting tools, it is possible to reduce the level of coal cutting noise, as well as provide benefits to other important areas of health and safety in underground mining.

Jan 1, 1983

By A Rozendaal

Namakwa Sands, a heavy minerals beneficiation business situated along the west coast of South Africa, is a major producer of titanium slag, pig iron, ceramics quality zircon and rutile concentrate to the international export market. The bulk of the economic mineralisation, which includes zircon, rutile, ilmenite and leucoxene is hosted by a late Cainozoic aeolian succession overlying remnant palaeo-strandline sediments. Relatively younger duricrust layers that cement a significant part of the generally unconsolidated ore compounds the challenging processing character of the primary mineralogy. The complex nature and hardness of the duricrust ore influence their mineability negatively, and can potentially destabilise downstream ore preparation processes. Effectively, up to ten per cent of the entire mineral resource is sterilised as the present infrastructure is not geared to treat the hard-mineralised ore. The metallurgical performance of the primary processing stage, which entails wet density separation, is strongly a function of the quality of the heavy mineral assemblage, liberation state of the economic minerals and slimes content. Elevated concentrations of garnet, a gangue contaminant exhibiting similar physical characteristics as the economic minerals, subtract substantially from the recovery performance of the secondary concentration process, which comprises mainly wet magnetic separation. By contrast, the intrinsic mineral purity of the economic fraction governs its successful recovery to saleable products as stringent product quality specifications apply. Improved mine planning through geometallurgical enhancement of the existing mineral resource model is envisaged to benefit the entire Namakwa SandsÆ mineral beneficiation chain, ultimately aiming to optimise mineral resource utilisation.

Jan 1, 2008

By T Hughes

Upward pressure on all mining operations is coming from the triple bottom line. To some extent this is being offset by the rise in mineral prices, but this may or may not continue. The other serious issue facing all companies is the replacement of economic reserves as exploration levels over the past decade continued to decline in line with falling mineral prices. In order to underpin the sustainability of the mining industry it is necessary to continue to reduce cost, reduce the mine environmental footprint, whilst increasing community benefit. At the same time it is imperative that we increase the economic reserves. The highest risk is in adding new mineral discoveries as the strike rate for economic discovery decreases. Gekko Systems Pty Ltd recognises that the most simple and risk averse route to increasing economic reserves is to reduce cut-off grade in the mine, thereby bringing formerly uneconomic reserves into the economic category. We have been developing a new process flow sheet which embodies the triple bottom line and the issue of economic replacement of reserves. This paper describes this flow sheet and presents four examples where this concept is/can be applied to bring about triple bottom line benefits. Sustainability can only be assured if we are the ones in control of our environment, costs and reserves.

Jan 1, 2007

By Bengt Fellenius

The conventional wave equation analysis without control of the representativeness of the parameters to the actual conditions does not provide accurate results. However, the representatives can be vastly improved by means of using the results of monitoring the dynamic response in a pile during driving. Dynamic monitoring displays the interaction of independent strain and acceleration measurements having directly propor­tional response to impacts, but inversely proportional response to re­flections from the soil. Examples are given and the CAPWAP method used to calculate from the measurements the dynamic pile and soil para­meters and mobilized soil resistance is outlined. The dynamic monitoring technique and analysis has been accepted internationally and been incor­porated into Building Codes. The prediction is offered that in five year's time, no major piling project will be undertaken without dynamic monitoring and analysis.

Jan 1, 1984

By N Strong

Cracow is a high-grade; low-tonnage underground gold mine located approximately 500 km north-west of Brisbane in Central Queensland. It is a steeply dipping, narrow vein, epithermal gold and silver deposit that is accessed via a decline from surface. Cracow is owned by joint venture between Newcrest Mining (70 per cent) and Sedimentary Holdings (30 per cent). The orebodies are 5 m wide on average and the ore is extracted via sublevel open bench stoping. Stopes are extracted to a strike of approximately 25 m before being backfilled with waste. Prior to the introduction of electronics, the mine would remove a small amount of the previous backfill out to create a void, and then begin blasting two to three rings at a time, with the ore being extracted between each blast. This method caused the ore to be blasted onto the waste backfill resulting in dilution of the high-grade ore. It also meant that the extraction of each stope took a number of weeks and numerous blasting events. In the fourth quarter of 2005, the mine struck a geotechnically sensitive stope, where all 20 rings had to be extracted in a single shot or risk possible geotechnical problems that could sterilise the ore. Due to the limitations of NONEL« delay detonators the mine could not fire all the rings in a single shot and needed to use an electronic detonator system to extract the stope. Some unexpected benefits to the mine were increased fragmentation, reduced vibrations, reduced dilution, improved efficiency and improved hanging wall and footwall conditions. After the success of this first electronic shot, the mine has since moved to firing all their stopes with electronic detonators. With electronics the mine has been able to fire much larger blasts, and has in fact moved to firing their blasts in the opposite direction, firing towards the draw point instead of into the waste backfill, thus reducing ore dilution.

Jan 1, 2007

By Edgardo Orderique

Southern Perú Copper Corporation ha desarrollado un programa de reevaluación de las reservas para optimizar cada etapa del proceso y así llegar a las reservas mencionadas. En este sentido, el presente texto desarrolla el esquema de optimización de una secuencia anual de minado. El proyecto comprende la realización de de perforaciones en zonas llamadas geometalúrgicas, con el fin de realizar pruebas metalúrgicas y definir el comportamiento del mineral en la concentradora y lixiviación. También se incorpora el concepto de índice de solubilidad, parámetro que sirve para diferenciar adecuadamente un mineral económico para flotación del de lixiviación y finalmente, se optimiza la secuencia anual de minado y disposición de material en botadero. En consecuencia, es importante determinar el uso de software y hardware adecuado para planeamiento de minado, ya que depende de la magnitud de la mina como en el caso deCuajone.

Sep 13, 2001

Analysis of rock discontinuities, collected using a scanline method, has been undertaken at the Iron Duke open cut mine, on the southern margin of the Middleback Range in the Gawler Craton, South Australia. The iron mineralisation, which is a product of supergene enrichment of carbonate sediments, is located on the W (western) limb of a gently N plunging D2 macrosyncline. Mesofolds plunge shallowly to the NE or steeply to SE, suggesting two shortening events, of which the second produced significant macrofolds. Discontinuities include:faults and shears which display variable orientations, mainly striking WNW dipping steeply N; mesofractures or joints maintaining a well constrained orientation, dipping steeply S, subvertical striking E-W; and bedding surfaces which are folded about a gently N plunging axis. Through this example of the regional control exerted on local discontinuities, it is clear that discontinuities are not randomly distributed as often assumed in purely statistical approaches. Commonly for rocks of any age there is a distinct discontinuity pattern, reflecting the geological deformation history. If the controls exerted on local rock discontinuities can be determined and assigned a number related to their significance, the way forward is available to develop a site specifc knowledge base that can make realistic predictions for any position in a given rock mass. Such a procedure would involve assessment of the regional geology, linked to scanned discontinuities either via manual or automatic means. Recent advances in automatic scanning rock faces (eg by the I-SiTE Laser Radar) to determine discontinuities distributions, enable the rapid calculation of rock characteristics. This is a significant advance in rock engineering, providing a method of safe and quick collection of data. However it creates problems in the presence of an increase in the geotechnical data available, which should be assessed in the context of the regional geology. Although techniques are underway to analyse post-blast discontinuities, the next signifant potential advance in this area could be the integration of a knowledge based system to assess discontinuities ahead of mining, incorporating regional assessment and human intuition.

Jan 1, 2000

By F. G. Scott

This document is a proposed program plan for mining environmental research to be conducted by the U.S. Bureau of Mines in support of industrial oil shale mining and processing. This program plan is one of three research alternatives being considered by the Bureau, each based on a different level of anticipated funding. This report documents the mid funding level program plan.

Jan 1, 1980

By Hans Hamrin

Three drill-blast cycles of 3.1 m advance achieved in one working shift of 7.5 hours at the Holsfjorden Tunnel project in Norway. The tunnel, 5235 m long, with a cross section of 8.6 m2, was completed several months ahead of schedule. This remarkable performance was achieved by a crew of 16 men, using machines specially designed for small tunnel excavation. The integration of drilling and charging into one unit, mucking and transport in another, reduced non-productive time considerably. The average cycle time of 140 min made it possible to complete three rounds in one 7.5 hours shift.

Jan 1, 1987

By C. Hosten, K. V. S. Sastry, D. J. Kawulok-Englund

Introduction Since the last decade the iron ore processing industry has undergone drastic changes from supplying screened and natural ores to manufacturing tailored concentrates and pellets. Increased need for the beneficiation of lower grade iron ore deposits and the increased demand for higher grade concentrates necessitate finer grinding of iron ores before concentration. The normal filtration stations used in the past are experiencing difficulties in dewatering the finely ground concentrates to moisture levels acceptable for balling. In addition to finer grinding, applications of complex beneficiation techniques has decreased the filterability of the concentrates and create problems in filtration of iron ore concentrates. An overview of the filtration literature indicates there are few research reports on the dewatering of iron ore concentrate slurries. There exists a need to understand the principles and mechanisms involved in the filtration of iron ore concentrate slurries with a goal of developing more efficient filtration techniques. This paper presents the results from the first phase of our research program that included the development of a reproducible benchscale filtration technique and the investigation of the filtration behavior of eight iron ore concentrates.

Jan 10, 1983

By A. R. T. Denues

The Explosives Division of the Bureau of Mines, United States Department of the Interior, is investigating cushioned blasting at the Explosives Testing Station, Bruceton, Pa. The general interests of this investigation are practical and relate particularly to safety. The immediate concern is an application of cushioned blasting in coal mining In cushioned blasting, various means are employed to reduce the intensity of the application of energy in an explosive action in a borehole. The primary object is to increase the efficiency of the use of explosives.

Jan 1, 1940

By A. R. T. Denues

The Explosives Division of the Bureau of Mines, United States Department of the Interior, is investigating cushioned blasting at the Explosives Testing Station, Bruceton, Pa. The general interests of this investigation are practical and relate particularly to safety. The immediate concern is an application of cushioned blasting in coal mining. In cushioned blasting, various means are employed to reduce the intensity of the application of energy in an explosive action in a borehole. The primary object is to increase the efficiency of the use of explosives.

Jan 1, 1940

By Yoginder P. Chugh

The characteristics of weak floor strata associated with actively mined coal seams in Illinois are very important from ground stability point of view and, in many cases, are the governing factors in determining the size of pillars and mine openings. Laboratory and field getotechnical characterization studies of weak floor strata were conducted at six mines during the period 1985-1988. Correlation analysis among engineering index properties, and laboratory, and field determined strength-deformation properties were conducted to identify simple tests which can be used to estimate ultimate bearing capacity and deformation properties of immediate floor strata. It was concluded that the ultimate bearing capacity (UBC) and strength- deformation properties of the weak floor strata can be estimated from simple tests such as, natural moisture content, atterberg limits, and axial swelling strain. Indirect tensile strength was found to be a better estimator of UBC than unconfined compressive strength.

Jan 1, 1989