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By R L. Brathwaite

As part of an investigation of the deep structure of the Waihi Basin, an extensive set of resistivity measurements was recently collected by DSIR Geology & Geophysics. The objective of this work is to map deep resistivity changes throughout the Waihi area in order to contribute to a better understanding of the regional geophysical structure. This research is also aimed at improving techniques for locating 'deposits of epithermal mineral resources, and helping to establish their origin and genetic relationship to fossil geothermal systems.   The results indicate that the basin south of Waihi is underlain by an extensive layer of low resistivity, modelled as a 5ohm-m layer several hundred metres thick. Lake sediments (mudstones), as exposed in the south western part of the basin, near Waitawheta, are the most likely source of this low resistivity layer, although hydrothermally altered clays and/or elevated temperatures are other possible causes. Strong northeast trending anisotropy is also observed, implying structural links from Waitawheta through to Golden Valley. The observed resistivity pattern is consistent with a æburied calderaÆ or æfaulted depressionÆ structural model for the basin, as inferred from gravity and magnetic data.

Jan 1, 1991

By Wilson A. F

The use of stable isotopic measurements as a technique for elucidating the origin and history of the water in hydrothermal fluids is relatively new. Recept studies have emphasized the importance of meteoric water in the formation of many hydrothermal ore deposits including many epithermal gold-base metal deposits which occur in faulted volcanic terrane. Other vein-type gold ores are believed to have formed from fluids of magmatic or metamorphic origin and exhibit characteristic d18O values. Preliminary oxygen and carbon isotopic data for some important gold deposits of eastern Australia have emphasized the diverse origins of their ore fluids.The Mount Morgan gold-copper orebody is shown to be of the volcanogenic massive sulphide type with ore fluids predominantly of sea water origin. The Charters Towers fissure veins formed during hydrothermal activity associated with intrusion of Lolworth Igneous Complex equivalents. Oxygen isotopic studies of the quartz reefs at Stawell and Gympie have been inconclusive. The ore fluids have a d18O value of about 7 per mil and may be of magmatic or metamorphic derivation.

Jan 1, 1981

By Robert S. Hendricks

LOCATION AND HISTORY The Lakeshore Copper property is located on the Papago Indian Reservation approximately 30 miles South of Casa Grande, Arizona. This major porphyry type deposit was discovered by El Paso Natural Gas Company in 1966. Following an extensive diamond drilling program, El Paso invited several mining companies, including Hecla, to examine the property with a view towards participation. Hecla's examination, and the attendant feasibility studies, led to agreements, which were finalized in September 1969, whereby Hecla would acquire a 50% interest in the property, and would act as operator. The Lakeshore deposit covers an area approximately 3,000 feet in width by 6,000 feet in length. It consists of an upper zone of disseminated copper oxides, averaging approximately 100' in thickness overlying a zone of disseminated copper sulfides up to 1,000 feet thick. Near the base of the disseminated ore is a blanket like zone of high grade copper sulfides, referred to as the tactite ore body. The mine is being developed to produce approximately 6,500 tons per day of oxide ore and 9,000 tons per day of sulfide ore. This represents a total daily production rate of 15,500 tons per day, which will be achieved by underground mining methods using rubbertired dieselpowered mining equipment. DEVELOPMENT LAYOUT The mine is being developed by two parallel 15° decline tunnels. The declines were collared 5,000 feet southeast of the ore body, and are being driven in a northwestery direction, to pass beneath the tactite ore zone. The declines will constitute the primary means of access to the underground workings. One decline (north

Jan 1, 1997

By S. Culp, P. Metcalfe

Web technologies and the Internet have revolutionized the computer industry. The Web browser technologies have also moved to portable devices such as Personal Digital Assistants (PDAs) and mobile phones. This paper looks at how to implement a Web Server solution and addresses some of the inherent advantages in the technology. It will also look at some examples of how plant productivity can be managed with a Web Server approach.

Jan 1, 2002

By M Carr, K Williams, W Chen, J Plinke

The depletion of iron ore deposits at the face of the mine site dictates the necessity for the exploitation of formerly less attractive orebodies to meet the demand of the modern world. These orebodies will typically be found close to or even beneath the water table where an increasing clay and moisture content will result. Problematic iron ores, colloquially termed as ‘wet and sticky’ material (WSM), can have a significant impact in the material handling stream due to the expensive downtime of processing equipment, which is attributed to the inter-particle and boundary cohesion and adhesion forces of the bulk material.In order to gain a better understanding of the causes of poor handleability, experimental test methods to determine wall adhesion, and inter-particle adhesion within bulk materials were developed. Based on the combination of wall adhesion and inter-particle adhesion measurements, with traditional methods of assessing bulk material handleability, a new method to assess the potential of bulk materials to cause handling problems is proposed. This method reduces the multitude of factors leading to problematic behaviour to a handleability index (HI) [0,1], which is easily assessed and understood. The method is suitable for adhesive materials and applicable for a wide range of material flow, from gravity reclaim stockpiles to transfer chutes and carry back on conveyor belts.Additionally, this research presents an assessment of the HI derived by experimental testing of three iron ore samples. A clear understanding of the problematic behaviour of the iron ore samples is achieved with the use of dust extinction moisture (DEM) tests, which indicates the regions where problematic behaviour may be experienced on-site.CITATION:Carr, M, Plinke, J, Williams, K, Roberts, A and Chen, W, 2017. Determination of the handleability index of adhesive bulk materials, in Proceedings Iron Ore 2017, pp 503–510 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By OWEN H. PERRY

One of man's primary tools is the ordinary screen. Whether of mesh or punched plate, it is fundamental in principle, primitive in its origin, and common in its application through all the world; and yet the screen goes only a part of the way toward the completion of its job of separating materials according to size. It will give a practical and continuous separation according to "size," as generally understood (accurate according to the breadth), but the accurate and continuous separation as to thickness is not a practical function of the screen. Still, all through history, the thickness of particles of material must have been important to many people; therefore, one would expect that some standard method of sizing for thickness would long since have been evolved and that equipment applying that method would be readily available to any in¬dustry. This, however, seems not to be so.

Jan 1, 1949

In a previous paper of this series (1) ,t it was shown that during the creep of single crystals of lead, deformation proceeded to some extent by means of slip on the octahedral plane. This was demonstrated by the formation of slip lines on the surface of the specimens. At first, a few broad bands appeared after a small amount of extension had taken place; then, as extension proceeded, more and finer lines made their appearance until the whole of the specimen surface was covered.The present paper deals with the process of deformation of the creep specimens as revealed by X-ray examination..By the use of this method, the changes taking place in the crystal structure can be observed.EXPERIMENTAL METHODThe method of preparation of the specimens, their size and the purity of the lead employed have been reported elsewhere (1). At frequent intervals, the specimens were dismantled from the test rack and X-ray back reflection photographs were taken. The specimens were so marked and set up on the X-ray machine that the same spot on the specimen surface was always examined.Copper radiation was employed, the tube voltage and current being 45 kV. and 25 m.a. respectively and the exposure time 2 hrs. The slit diameter was 1 mm.

Jan 1, 1941

The Winton Basin is one of three Southland sub-basins. The oldest known sediments are Early Oligocene terrestrial shales, sands and lignites deposited in half grabens formed as a result of oblique extension. A marine transgression in the Oligocene deposited mid-outer shelf to upper bathyal mudstones. Shallowing of the basin and tectonic quiessence lead to limestone deposition in the Early Miocene. Regional tilting led to uplift in the north and east and deposition of terrestrial lignites and gravels across the basin and the basement high to the south.

Jan 1, 1992

A model was developed to facilitate secondary tailgate support selection based on analysis of over 100 case studies, compiled from two different surveys of operating longwall coal mines in the United States. The ALPS (Analysis of Longwall Pillar Stability) program was used to determine adequacy of pillar design for the successful longwall case histories. A relationship was developed between the secondary support density necessary to maintain a stable tailgate entry during mining and the CMRR (Coal Mine Roof Rating). This relationship defines the lower bound of secondary support density currently used in longwall mines. The model used only successful tailgate case history data, with adequate ALPS SF according to the CMRR for each case. This model facilitates mine design by predicting secondary support density required for a tailgate entry depending on the ALPS SF and CMRR, which can result in significant economic benefits.

Jan 1, 1996

By A. Duerksen

"Surface coal mining in West Virginia has supplied energy to the eastern coast of the United States for over a century. Over the years, the coal mining industry has been forced to adapt as societal demands regarding health, safety, and environmental impacts have changed. More recent pressure has called for another iteration of change: long-term post-mining sustainability. The research discussed in this paper investigates one potential solution - or component of a solution - to improve the sustainability of surface coal mining in West Virginia: post-mining wind power. The paper begins with an introduction to the Appalachian region of the U.S. and the role that mining has played in its history, followed by a discussion of the need for sustainable mining and how post-mining wind power may help fulfill it. Data processing methodology of field data from monitoring locations is then explained. The results are then used to estimate the electrical output of a wind turbine. This data is then utilized in a case study discussion of one of the monitored sites. The paper concludes with an analysis of the broader implications of the research and a discussion of future work."

Jan 1, 2011

By G. K. Rogers

The portal, which is the near-horizontal, surface point of entry to an underground excavation, can often be an exceedingly difficult area in terms of ground control. Surface and subsurface failures at portals, as discerned during a study involving over 300 case histories, are unfortunately, common. To aid in the engineering evaluation of portals, the Geomechanics Classification System was appended with discontinuity orientation assessment values and support/excavation guidelines. Also, a design model utilizing RMR predicted rock loads in conjunction with half-dome theory is proposed for the most common type of portal failure. Other pertinent comments and recommendations relating to portal stability are included.

Jan 1, 1989

By R. E. Kennedy

"INTRODUCTION In a previous publication4 results were given of numerous experiments made on the in-flammability of gas mixtures consisting of methane, hydro a. carbon monoxide, nitrogen, and carbon dioxide. Data were obtained and tables prepared giving the inflammable limits of each of these combustibles when mixed with various proportions of carbon dioxide and nitrogen. By the use of these data and the application of Le Chatelier's law, it was found possible to calculate the limits of inflammability of any gas mixture containing any or all of the above gases.Various mixtures of the five gases given above were prepared and their limits determined experimentally and then calculated. Good agreement was found between the determined and calculated results when complex gases encountered in mine safety work were tested. Of special significance was the accurate calculation of the limits of inflammability of gases from mine fires, gases from mine explosions, detonation products of explosives, blast—furnace gases, automobile exhaust gas, and other gases of a similar character.Using the method given in the above report, Yeaw5 investigated a number of industrial gases including oven, coal, producer, blue, carbureted blue, and dry quencher gases, and found the determined and calculated results to agree remarkably well, thus giving further proof of the value of such a means of determining dangerous conditions when combustible gases are encountered in practice.GASES FROM A POTASH MINEGases were recently encountered in a potash nine in New Mexico, containing the com-bustibles, methane, hydrogen, and ethane. In one special case a mild explosion occurred when these gases were mixed with the right proportions of air and ignited it therefore became necessary to know the inflammability of these mixtures in order that the proper precautions could be taken to prevent explosions."

May 1, 1932

By P J. Mienie

The Palaeo-Proterozoic Transvaal Supergroup in the Northern Cape Province of South Africa is host to the largest known resources of high-grade hematite ore on the Southern African continent. These ores are currently being exploited at Sishen and Beeshoek. Hematite occurances on the Sishen South exploration project (some 65 km south of Sishen mine), are at present the focus of an intensive investigation. At both the Sishen and Sishen South deposits, mineralisation is found within lithologies belonging to the Transvaal and Oliphantshoek Supergroups. The Transvaal Supergroup comprises a basal, carbonate platform sequence (the Campbell Rand Subgroup) overlain by thick units of banded iron-formation belonging to the Asbestos Hills Subgroup. The Asbestos Hills Subgroup is unconformably overlain by sedimentary rocks of the Gamagara Subgroup. The latter Subgroup has been correlated with the lowermost unit of the Oliphantshoek Supergroup. The Sishen and Sishen South deposits are located close to the western margin of the Kaapvaal craton and have been subjected to intensive, structural deformation. Both localities have undergone folding, faulting and thrusting. Early regional tectonism (2400 - 1700 Ma) played a critical role in the genesis and preservation of the ores from younger erosive events. At both deposits, four similar iron ore occurrences have been recognised. The ores have developed in specific depositional environments and hence display unique physical, chemical and metallurgical properties:The bulk of the high-grade hematite comprises laminated and massive ores, which are found in the upper parts of the Asbestos Hills Subgroup. The laminated and massive ores are best developed in basinal and pseudo-graben structures. Collapse breccia ores of medium- and lower-grade are preserved within deep palaeosinkholes. The sinkholes have developed within the dolomites of the Campbellrand Subgroup. Lower-grade conglomeratic and gritty ores constitute the remainder of the deposits. These ores are found in the overlying clastic succession of conglomerates, shales and quartzites belonging to the Gamagara Subgroup. Although, there are many stratigraphic and lithological similarities between the Sishen and Sishen South deposits, there are also important differences, which will impact on the profitable exploitation of the ores. The most striking contrast between the deposits is their size and geometry. Sishen mine is a single pit operation with an opencast mineable reserve of 895 Mt. The Sishen orebody is thicker, more continous and significantly larger than the Sishen South deposit. The Sishen South deposit has a potential opencast reserve of 228 Mt. It comprises a number of small and narrow, isolated orebodies, spread over an area of ¦64 km2 . There is a significant difference in grade between the deposits. On average the orebodies of the Sishen South deposit have a higher iron content (+0.25 per cent Fe), less potassium (- 0.090 per cent K2O) and less phosphorus (-0.019 per cent P). The Sishen South deposit has less interbedded shale in the laminated and massive ores. The footwall of these high-grade ores is a light-density, intrusive sill, compared to banded iron-formation at Sishen. With a proposed heavy-medium separation plant at Sishen South, the impact of dilution on product grades is expected to be less than that currently experienced at Sishen.

Jan 1, 2002

By Osama Safaqah

The new Cooper River Bridge will replace two existing bridges along U.S. Highway 17. The cable-stayed bridge will be one of the largest in the U.S and will connect the City of Charleston and the town of Mount Pleasant, South Carolina. The 1,546-foot long main span over Cooper River is supported by two diamond-shaped towers and will allow for 1000-foot wide navigation channel. The Charleston high-level approach is approximately 4351-foot long and will provide 250-foot wide navigation channel over Town Creek, while the Mount Pleasant high-level approach is 2090-foot long. Due to the high seismicity in the region, potential vessel impact, and hurricanes, large lateral loads are expected. Among various types of foundations, 10-foot diameter drilled shafts were selected for their high capacity against lateral loading. The shafts are founded on a stiff to very stiff lightly cemented calcareous sandy clay or sandy silt layer, called Cooper Marl, which underlies coastal sediments of interbedded clays and sands. The main towers will be supported on a group of 11 shafts and protected from ship collision by a rock island. The High Level Approach piers will be supported on a pair of 2 shafts. The shaft tip elevation is up to 230 feet below water line. An elaborate geotechnical investigation has been conducted on the site including a load test program on full-scale shafts under axial and lateral loads. The results of the tests were used to calibrate the lateral and axial soil resistance. The objective of this paper is to present the different aspects of the bridge foundation design.

Jan 1, 2005

By John E. Rourke, O&apos

This paper describes some of the results of a project for the design and demonstration of subsidence monitoring systems for underground coal mines. The project was designed to test monitoring systems described in an earlier feasibility report (O'Rourke and others, 1979). General objectives of the project were to develop reliable cost- effective monitoring systems for use above caving- type mining operations, over supported mines, and in urban undermined areas. Topics selected for discussion in this paper include a description of the instrumentation systems, the site conditions, problems of installation, resulting recommendations and an over- view of subsidence performance data obtained. There were some particularly difficult problems of installation to overcome at this site. Some of these could be experienced at any surface or under- ground project, others are probably more directly related to Western coal fields. Almost any subsidence monitoring program may face the following difficulties:

Jan 1, 1982

By J. E. Friant

The Mini-DiscTM cutter drill bit is a radical design departure from the traditional tri-cone rockdrill bit. Miniature disc type cutting tools as small as 3.25 inches (82.5 mm) diameter are fitted to a bit body to cut individual concentric kerfs. The action is the same as that commonly used on large tunnel boring machines but miniaturized. The high performance rate and efficiency of a disc cutter are the result of producing a large proportion rock chips rather than sand or powder. The Mini-DiscTM drill bit, referred to as the “Disc Bit” has other unique features as well. It can be re-greased between runs. It can be rebuilt in the field in about 15 minutes, cutters can be replaced and the Disc-Bit appears to require less down hole hydraulic power than conventional bits. Thoroughly tested in the laboratory, the bit has recently been undergoing field trials in well drilling, blast hole drilling and shaft drilling. As any engineer knows, the laboratory can not shake out all the problems but it eliminates the more glaring weaknesses. Performance results have been exhilarating, and a few mechanical problems were discovered and largely overcome. This paper is a progress report.

Jan 1, 1999

By Walter R. Curtner

Many, if not most, of today's pollution liability claims are related to events ("occurrences") that happened in the past. This fact creates an opportunity to obtain a large amount of insurance coverage at essentially no cost. Furthermore, in many cases, this insurance coverage is readily available. Scenario #1 For some 15 years, an underground gas tank has had a slow leak. The leak has now been discovered because the gas has contaminated nearby wells. As a result, an expensive $1 million cleanup is required. In addition, a liability suit has been filed for damages due to the contamination of nearby wells. Consequently, legal expenses are being incurred. Are all of these actual and potential costs insured? Obviously, if you have a pollution liability policy in place, the above costs will probably be insured. I say probably because business liability policies are not uniform. But, what if you don't have a pollution liability policy and what if your current general liability policy excludes all pollution liability (as most of them do today)? Under these circumstances, it first appears there is no insurance for this $1 million cleanup and liability suit. But this is probably not the case. You may well have insurance coverage, and you may well have much more insurance coverage than you ever expected. And, the insurance that I'm referring to is already in place. You simply need to find it and learn how to use this insurance - I'm referring to your old policies. In many cases, old liability insurance policies provide coverage for claims made today, because these policies were written on an "occurrence" basis of coverage. In fact, most still are written this way. This means that the insurance policy covers bodily injury or property damage liabilities (as defined in the policy) arising out of' "occurrences" or accidents that happen during the policy period regardless of' when the claim for damages is made. Therefore, for insurance purposes, the key question is: when did the "occurrence" take place? If someone falls and breaks a leg, that is clearly an "occurrence." The broken leg occurrence is, therefore, insured by the liability policy that was in existence at the time of the fall - regardless of when the claim or suit is filed, if ever. However, the answer to this question is seldom an easy one when you are looking at a pollution claim. In our scenario, the tank had a slow leak over 15 years, but property damage was not discovered until now. The question of when the "occurrence" (as defined in the insurance policy) took place has been litigated and continues to be litigated in many courts across the country. But, most often the answer has been that, for insurance purposes, the "occurrence" is the entire period that the tank was leaking (15 years), even though the contamination to the water was not discovered until 1987. This means that the person or company that is insured can potentially use all of its general liability policies (if they are "occurrence" policies, and most were), which were purchased during the 15 years from 1972 until 1987. And, these policies will potentially insure all of the claims and related exposures that arise out of this leaky underground gas tank. Scenario #2 In our first scenario, the claims and expenses were insured by past general liability policies because the claims arose out of events in the past, which, in turn, caused damage. Let's look at another example. In this scenario, Company XYZ has received a request to help clean up a landfill site because 10 years ago, XYZ dumped some toxic substances at the site, which was totally legal at the time. XYZ has not dumped anything at the site since this time. Nevertheless, XYZ is now being required to contribute $2 million to the cleanup of this site. In this scenario, if you had purchased "occurrence" general liability policies 10 years ago, these 1977 policies would (potentially) apply to the current $2 million cleanup claim. And, the reason is that the "occurrence" leading to the 1987 claim took place in 1977.

Jan 10, 1987

By J. de Villiers

Through the application of the Rietveld method, X-ray diffraction analysis has developed into a fully quantitative method for phase analysis. The Rietveld method itself has progressed from an unstable method that required constant operator intervention to a stable and robust method suited even for routine analysis. The method, however, requires a good initial calibration and periodic checks on its precision and accuracy. Several examples from minerals processing, pyrometallurgy, and materials science show the strengths and applicability of the method. The limitations and sources of error are also discussed.

Jan 1, 2007

By Bibhu Mohanty, Sheng Huang

Accurate measure of fragment size distribution is a key objective in all blasting and crushing operations. Several generic distribution functions have been devised to describe the degree of fragmentation for the representative range of fragments from selected measurements. The application of four distribution functions, i.e. Rosin-Rammler, Swebrec, Grady and Gilvarry, in describing fragment size distribution of impact-induced fragmentation of a limestone rock has been investigated. A modified Hopkinson Pressure Bar experimental set-up is used to control both impact velocity and energy input into the target rock. The feed size in the sample holder is varied from 6.35mm to 15.88mm in three ranges and the impact velocity up to 14m/s. The size distribution in the product is determined by sieve analysis for a range of impacts. The experimental results are fitted to the four distribution functions to examine their relative accuracy and reliability.

Jan 1, 2016

By Gunnar Nord

Introduction ??Atlas Copco has customers both amongst Miners and Contractors ??We believe that the contractor's approach to tunnelling is worthstudying ??For a tunnel contractor the incentive is speed as ?30 % of the costs are material related ?70 % of the cost are time related ?A tunnel contractor favours utilizing of the face ?A miner favours utilizing of the gear ??Statement; In mining, a long term average advance rate of more than 10 m / day can be achieved with the excavation techniques availabletoday

May 1, 2009