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By Roy McKinstry, Mark Rantapaa, Thomas Bolles

"More efficient drilling and blasting techniques have shown measurable improvements in throughput at the Barrick Goldstrike wet grinding mill.A decrease in throughput at the autoclave, due to increasingly hard ore, was identified in early 2002. A team of individuals from the Open Pit and Process areas participated closely on the Drill-to-Mill (D2M) Continuous Improvement initiative to ensure that it would address the needs of both groups, with the target of improving throughput in future years, despite the projected harder ores. Plant studies were conducted to determine if adjustments to drilling and blasting could positively influence throughput. At the Goldstrike mill the greatest opportunity from the D2M initiative is realized on the hardest ore. Grinding throughput for softer ore, <15 kWh/st, can meet or exceed the downstream pressure oxidation requirements. Grinding throughput for harder ore, >15 kWh/st, is limited by the SAG milling capacity. Better fragmentation in the D2M ore, as demonstrated by image analysis, increased throughput 5% to 10% (25 to 50 stph) compared to the standard mining methods.Better fragmentation and a subsequent increase in mill throughput were achieved through the use of:1) Electronic caps for more precision and flexibility, as well as for allowing extremely fast shots.2) Explosives with a higher velocity of detonation (VOD), to provide for improved shock energy.3) Improved distribution of the explosives by decreasing pattern spacing.INTRODUCTIONThe Barrick Goldstrike Open-Pit group, along with the Process division, began experimenting with novel blasting technology and techniques to improve mill throughput in the spring of 2001. A series of tests were developed to determine if fragmentation and ultimately mill throughput could be influenced by optimizing the drilling and blasting program in known"

Jan 1, 2004

Early in 1940 the development and sampling programmes in hand on the North and British Sections of North Broken Hill Limited were such as to necessitate the drilling of a large number of drill holes ranging up to about thirty feet in length. On the British Section, one purpose was to test the existence, width, and value of narrow lodes believed, for geological reasons, to occur in the walls of the existing workings. Another object was to definitely disprove the existence of payable shoots of ore in certain largerhodonite and quartz-garnet (&quot;garnet sandstone&quot;) pillars which had been formerly left as unpayable.On the North Section, the main purpose of the short holes was to delineate the ore-body boundaries by drilling laterally from drives in ore, and thus enable level layout to be planned in advance of sill stoping. It was also desired to test the walls of stopes in those portions of the mine where the economic limit of mining is not rendered obvious by a clear-cut wall, but should be determined by assay. In these latter cases it was hoped to eliminate &quot;prospecting by stoping,&quot; a procedure by which any doubts as to the existence of further good ore behind the low-grade walls were settled by continuing to stope laterally until all chance of such an occurrence was removed.LONG HOLE ROCK DRILLINGFollowing an investigation of recorded instances of similar practice elsewhere it was decided to use the rock drill for a series of trial sample holes. A 3-in. drifter was used. This was selected from those in use underground, and was given a special overhaul; had a new machine been purchased, a 4-in. type would probably have been obtained as being more suited to the work. The rods were H in. hollow round steel with a type &quot;1&quot; Jackrod thread. Couplings were of chrome steel, and were H in. in diameter, and 2 in. long. Jackbits (type &quot;1&quot; thread) in sizes from 2 in. to 4 in., with 1-in. gauge changes, gave a range of nine bit sizes. They were resharpened by hot milling, and were not milled to a definite gauge size.After sharpening, bits were sent underground without sorting into sizes, the drillers selecting the next bit with callipers. In view of the small scale of operations, it was not considered worth while to adopt special measures, such as the cold grinding of bits, which might have given a better product. Later, however, new bits were used exclusively, the idea being to accumulate enough blunt Jackbits to warrant a thorough treatment of the sharpening...

Jan 1, 1941

By Timothy J. Rohrbacher

This report presents results from an ongoing U.S. Bureau of Mines study defining domestic coal reserves. Examinations of five 7 ½ -minute central Appalachian quadrangles have been completed to date. Only 26.4%, 5.0%, 6.5%, 8.2%, and 4.2% at the coal resources remaining in the Matewan, Boltsfork, and Hoskinston, KY; Vansant, VA; and Beckley, WV quadrangles, respectively, constitute economically recoverable reserves. An evaluation of the coal mining industry&apos;s impact on the economy of Pike County, KY, wherein the Matewan quadrangle is located, was also completed in order to provide a basic understanding of the influence of coal mining on the local economy. Results show that coal mining is the only major income producing industry in Pike County, accounting for about 46% of the county&apos;s income, and 21% of the total available employment, in the base year 1990. If similar results are found in subsequent investigations, a strong argument can be made that traditional coal producing regions may soon be experiencing resource depletion problems far greater and much sooner than previously thought. This will affect not only the coal industry but, given the obvious dependence of Pike County&apos;s economy on its coal mining industry, the entire social and economic infrastructure of large areas.

Jan 1, 1994

By D. Newman

Multiple seam mining is prevalent in Southern Appalachia because economically mineable coal seams are numerous and frequently occur in close vertical proximity. West Virginia, Kentucky, and Virginia have 117, 55, and 40 mineable coal seams respectively. It is extremely rare to have an underground mine that has not been undermined, overmined, or has mining adjacent to it. In many cases the multiple seam mining is concurrent with extraction sequenced in superjacent seams. Because underground mining is focused on recovering the most valuable reserves, mining is rarely practiced from the top seam down, which is the practice most conducive to stability. The combination of room-and-pillar mining methods that include development only, small block, partial retreat, full retreat, and longwall mining produce a wide range of mining geometries and complexity in underlying and overlying seams. In the future, the number of multiple seam operations will increase as reserves are depleted and future mines are, by default, located closer to abandoned mine workings. The improved coal market has transformed many formerally uneconomically mineable seams into attractive reserves. The approaches and methodologies used for multiple seam stability analysis are dictated by the site conditions, including overburden/interburden thickness and lithology, mining geometry, and the mining methods in both the active and abandoned mines. Multiple seam stability analysis using analytical and numerical methods is illustrated by two case histories that reflect close proximity room-and-pillar mining and mining in bump prone situations.

Jan 1, 2007

By Daniel P. Lathrop, Leslie C. Taylor, William L. Fourney

Except when the target is on the surface, e.g. a tank track, the most important loading mechanism from a buried charge on a target above it is the impact of soil propelled at the target by the expanding gas from the explosion. Detonation of a shallow buried explosive generally yields an unstable interface between the rising soil and the air which appears to be the result of Richtmyer-Meshkov instability. Irregular “fingers” of saturated sand extend into the air above a more generalized dome of soil. These fingers move at a much higher velocity than the material between them at smaller stand off distances. As a result, the local load on the target at positions on the target at the same distance from the charge may vary by 50% or more from shot to shot or even within a single shot. This variation requires a large design safety factor to assure the integrity of design of mine-resistant vehicles.

Jan 1, 2009

By Mohammad Eslami

The Tabriz-Urmiyeh Highway shortens the distance of north-western cities of Iran by about 130 km, resulting in improved access and efficient transit between Iran and Europe through Turkey. The highway crosses the Urmiyeh Lake, an inland lake surrounded by mountains. Due to the circulation of salt-water in the lake and the necessity to continue shipping between adjacent ports, a waterway should be kept open. Consequently, a bridge was built to provide access of marine traffic. A causeway bridge had a length of 1,260 m, comprising of 19 spans. In construction of the bridge, more than 400 piles having a total length of 32 km have been driven. For design of piles different methods have been used such as static analysis, dynamic testing, and correlations to in situ tests, such as cone penetration test (CPT). This paper presents construction of bridge substructure, full-scale piling tests, and methods of analysis used in the evaluation of the deep foundation capacity. The presentation includes an assessment of four current direct CPT and one CPTu methods to calculate the bearing capacity of the piles. It was found that the CPTu and dynamic testing are two suitable tools for rapid and optimum pile design and verification.

Jan 1, 2010

By K. A. Lapakko, D. A. Antonson

Fourteen samples of pyrite-bearing Archean greenstone rock (d < 6.35 mm, 0.04% < St < 1.22%) were characterized (particle size, chemistry, mineralogy) and subjected to laboratory dissolution testing. The only sulfide and carbonate minerals identified were pyrite and siderite, respectively. Quartz, chlorite and sericite typically comprised 90 to 98 percent of the mineral content. For the first 60 weeks, seven samples with sulfur contents less than or equal to 0.16% produced drainage pH values exceeding 6.0. Over this period, six of the seven samples with sulfur contents greater than or equal to 0.20% produced drainage pH below 6.0, with minimum values ranging from 3.2 to 4.7. The seventh sample (0.72% S) had a siderite content of 18%. Small amounts of magnesium and, to a lesser degree, calcium carbonates present in the siderite apparently dissolved to neutralize acid and maintain drainage pH above 6.0. Sulfate release rates generally increased as sulfur content increased, and the rates of pyrite oxidation estimated for individual samples were roughly half to five times that reported in the literature for the abiotic oxidation of pyrite by oxygen. Observed neutralization potentials ranged from 0.2 to 2.0 g CaCO3/g rock.

Jan 1, 2002

By Upendra L. Karna

The pile capacity gain with time evaluated and implemented for the construction of the Route 21 Viaduct in Newark, NJ, U.S.A is discussed in this paper. The project consisted of the replacement of more than 3.2 km of viaduct and ramps. The project site consists of thick residual materials deposited by the Wisconsin Glacier over sedimentary rocks. The upper portion is glacial-lacustrine deposit underlain by marginal morainic till and stratified drift. Subsurface investigations identified significant variations in layer thickness and grain size consistency. The site was characterized into 4 Soil types, based on subsurface soil behavior. Closed end 600 mm and 450 mm diameter driven pipe piles were used for the foundation. Loading tests conducted during an advanced construction contract, established that a significant soil set-up could be expected. For the first construction contract, a pilot loading test program consisting of 112 dynamic loading tests and 77 re-strikes (at 2 to 4 weeks) using the PDA (Pile Driving Analyzer) with CAPWAP (Case Pile Wave Analyses Program) was conducted to establish the soil set-up behavior. Nine (9) quick static loading tests were conducted to substantiate the long-term pile capacity. Based on the loading test results, average set-up factors were established and utilized for developing production pile driving criteria. Bearing resistance with depth was analyzed and reviewed. The set-up factors varied significantly, ranging from 1.05 to 1.89, and averaged about 1.30. Conclusions are derived. Set-up factors behavior for each soil type plotted by linear regression are presented and discussed. An appropriate set-up with time relationship for a glacial soil is suggested.

Jan 1, 2006

By Juliana Colacioppo

La voladura es un procedimiento que está diseñado para obtener pilas a través de una fragmentación adecuada para el carguío y transporte, aumentando así la productividad de las palas y camiones y asegurando la estabilidad de los taludes y condiciones del piso de los bancos en la mina. Asimismo, el diseño de la voladura debe optimizar las operaciones posteriores tales como chancado, zarandas, clasificación, molienda, flotación y lixiviación. En ese sentido, el presente texto describe la metodología de optimización de procesos de la miina Antamina hasta la oncentradora a través de la recolección de datos de campo, caracterización, modelación matemática y simulación de las operaciones, donde además se utilizan sistemas de rastreamento de minerales y de análisis continuo de imágenes.

Sep 9, 2007

By Larry Rayburn

In the spring of 1999, construction commenced on the new Steelers Football Stadium in downtown Pittsburgh, Pennsylvania. Richard Goettle, Inc. (RGI) was the successful bidder to install the specified augercast piles for the foundation package. Description - Pittsburgh Steelers Stadium The new stadium will house the Pittsburgh Steelers Professional Football Team. It is widely believed that if a team is provided with a modern playing facility, that a winning season will ensue (Not always the case). The new stadium location is on the north side of Pittsburgh on the Ohio River, and just downstream of the confluence of the Monongahela and Allegheny Rivers. The site is west of existing Three Rivers Stadium. The Three Rivers Stadium was built during the late sixties and housed both the Pirates Baseball and Steelers Football Teams. The Public Auditorium Authority elected to replace this outdated stadium with two new stadiums, one for each professional team. The landmark stadium was imploded in February of 2001.

Jan 1, 2001

The Illawarra District, from 50 to 100 miles south of Sydney, is one of the State&apos;s important coalfields. It extends from Clifton on the north, to the Shoalhaven river on the south, and from the coast westward beyond the coastal scarp.For descriptive purposes, this area falls naturally into two zones:(a) the coastal belt backed-by the eastern edge of the plateau;(b) the plateau, westerly from the coastal scarp.(a) The Coastal Belt.A triangular shaped area extending from Clifton to the Shoalhaven river, composed for the most part of soft coal measures strata of Permian age, which, on weathering, undermines the massive overlying Mesozoic sandstones and causes the gradual recession of thecliffs.South of Wollongong, upper marine sediments and contemporaneous igneous rocks make their appearance beneath the coal measure beds and occupy the greater portion of the coastal belt.(b) Plateau Area.Extending westerly from the coastal escarpment is a plateau known as the Robertson Tableland, composed of Triassic sandstone and shales dipping gently in a northerly direction, and capped in places by Wianamatta. shales and r.rertiary basalts. This tableland is approximately 2400 feet above sea level in the vicinity of Robertson, and gradually falls to about 750 feet at Waterfall.The plateau area for the most part is highly dissected, rough, steep gorges alternate with sharp ridges.A large part of the northern watershed of the Robertson tableland is a reserve for Sydney water supply, and large dams have been constructed at Cataract, Avon, Burke, and Cordeaux.

Jan 1, 1938

By Krogerus. H., P. Jokinen, T. Lintumaa

Keywords: Pyrometallurgy, furnace, coke, smelting charge, optimization, ferrochrome The main consumer of ferrochrome is stainless steel production. Stainless steel must maintain a reasonable price against other competitive materials. Therefore, the ferrochrome price must be low enough and profitable for the producers of stainless steel. The investment and operational costs of ferrochrome production are greatly dependent on the availability of the process and the production rate. Thus the furnace size and production rate in submerged electric arc furnaces will be greatly increased in the near future. The ferrochrome production per furnace, e.g. at Outokumpu?s Tornio Works, increased from 30 000 t/a to 165 000 t/a in about 35 years. The same trend will continue globally but now much more quickly. The Outokumpu ferrochrome process at Tornio Works uses sintered chromite pellets and upgraded lumpy ore as a chromite source. Metallurgical coke is used as a reductant. Reliable smelting in a large furnace demands the correct charge composition and well-known characteristics of the charge components. The quality and electrical conductivity of cokes (normally used) has the most important role for the electrical conductivity of the smelting charge. The results of the measured electrical conductivity of different cokes and the smelting charge with many controlling factors are presented here. These measurements were performed over the years for our own purposes at the laboratory of Outokumpu Research Oy (ORC), in Pori, Finland.

Jan 1, 2006

By J. W. Thompson

LIMESTONE DEPOSITS. Limestone deposits that have not been demonstrated to be of such quality as to give them any substantial value over other limestone deposits of the same region, are not regarded as minerals. Gray Trust Co., In re, 47 Land Decisions 18, p. 20. OIL AS A MINERAL. Oil is a mineral substance and its removal will greatly impair the value of the land from which it is removed. Texas & Pacific Coal & Oil Co. v. Howard. Southwestern 735, p. 737. Tex. Clv. App. 212 OIL AND GAS AS MINERALS OWNERSHIP. Oil and gas are minerals and so long as they remain in place they belong to the owner of the land under which they are found and such owner has the right to explore for the oil and gas on or under his land and when found to remove and possess the same. Kimbley v. Luckey, Okla. - 179 Pacific 928, p. 831. OWNERSHIP OF MINERALS LACHES NO BAR. The owner of minerals in land can not be barred by laches for failing to assert his ownership where his title had not been ques- tioned and his right invaded. No lapse of time bars one's right to property and it is only in case his right has been invaded that it can be barred by laches.

Jan 1, 1920

By D. Grobbelaar, A. Cichowicz, D. J. Birch

The Q-coda method for estimating the quality factor Q(f)= Qo(f)n was used to characterize seismic wave attenuation in a region of the Kaapvaal Craton that includes the mining areas of the Bushveld Complex and Witwatersrand Basin. Seismic waveform data, collected by locally distant stations of the South African National Seismograph Network (SANSN), consisted of mining-related events with magnitudes ranging from ML 1.8 to ML 4. Q was calculated for nine different source-receiver pairs spanning the study region. A weighted average Q based on the number of available data gave an estimated attenuation relation for the study region of Q(f) = 327 f 0.81.

Jan 1, 2015

By K. Rambha Devi

The paper is an attempt to co-relate the findings of pile capacity using a number of formula suggested by various authors with the actual field load test results. Five locations consisting of wholly sandy or clayey soils were selected for this purpose. The clayey soils are on a hilly area having clays of medium to stiff consistency upto a depth of 20 m The sandy soils are near the bank of a river having angle of internal friction &apos;Ø&apos; value ranging from 30 to 35 Degree. The details of the soil properties are given in Table-1 Bored cast-in-situ piles of 30 cm diameter and a length varies from 6.5 m to 13 m were designed and cast for load test to be carried out. The load applied was twice the design load. The load vs settlement curves were obtained. The theoritical values obtained by formula suggested by various authors were superimposed on the curves. From the careful study of these curves it is seen that De Ruiter and Berigen values are close to the actual results for clayey soil. For sandy soil it is found that both the BIS method and Meyerhof method found to give conservative resuslts. A multiplication factor is suggested to theoritical values for obtaining satisfactory results.

Jan 1, 1996

By Dave Rose, Jacques McMullen

"The Detour Lake mine is located 200 km northeast of Timmins, Ontario, Canada.The mill processes a free milling gold ore using both a gravity circuit and leaching with a state-of-the-art carbon-in-pulp circuit. The grinding circuit is a conventional SABC circuit with a tonnage of 55,000 tpd at 95 microns with the addition of pre-crushing upstream of the SAG mill.The Detour Lake mine has one of the largest gyratory crusher in the world (60"" x 113"") and over the years, many improvements have been made to this crusher with the result of improving plant throughput. This paper will present how choke feeding the gyratory crusher has been found to be one of the main influences on crusher product particle size and plant throughput. It will explain how the effect of choke feeding the gyratory was measured and from that, the various changes made to improve choke feeding of the gyratory crusher.IntroductionOre is hauled from the open pit mine and dumped directly into a single 60"" x 113"" primary gyratory crusher. The live capacity of both the feed and discharge hoppers of the gyratory crusher are designed for two (2) truck loads each, assuming a nominal payload of 300 tonnes per truck. The surge bin under the primary crusher feeds an apron feeder that controls the ore feed rate at approximately 4,200 tph onto a 227 metres long x 1.52 metres wide belt conveyor with a nominal capacity of 4,200 tph.The primary crusher is operated at an open side setting of 172 millimetres to produce a F80 feed to the secondary crushing circuit of 135 millimetres."

Jan 1, 2017

By B Murphy

Traditionally comminution optimisation has been focused on energy minimisation, whereas flotation optimisation has been focused on recovery improvement. One of the largest, if not the largest, operating cost over the life of a flotation circuit is electrical energy. With increasing pressure on operators to lower production costs and the cost of energy increasing, reducing the energy consumption of the flotation circuit can be beneficial to site economics. This paper reviews the use of energy by mechanically agitated flotation machines and discusses the measurement and benchmarking of energy consumption in modern flotation concentrators. Opportunities for improving flotation energy efficiency are also identified.CITATION:Murphy, B, 2013. Flotation energy consumption and opportunities for improvement, in Proceedings MetPlant 2013 , pp 399-412 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By D Smith, A Ramdhani, J Francke

Ground penetrating radar (GPR), a well-established geophysical technique generally used for shallow civil engineering applications, has, in the last decade, found increasing acceptance as a complementary tool in mineral resource evaluations. As new sites are trialled with the method, a greater understanding is being garnered regarding the most suitable environments for long-range radar. Although successful projects have been conducted worldwide for mineral sands, iron ore and alluvial projects – tropical weathering environments have produced some of the most impressive results. Specifically, tropical nickel laterites have shown to be, with some notable exceptions, ideal GPR environments.Such high-resolution remote sensing has particular relevance to bulk commodities or those which possess significant rheological variation within geological units, and has led to some innovative downstream uses within exploration, project development and the larger mining industry. In this paper, we examine the application of long-range GPR in Indonesian nickel laterite deposits in general, to highlight some of these novel applications with particular reference to resource modelling, mine geology and operational economic implications.CITATION:Francke, J, Smith, D and Ramdhani, A, 2014. Ground penetrating radar to enhance the exploration-to-mining value chain, in Proceedings Ninth International Mining Geology Conference 2014 , pp 175–182 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By Jeffrey A. Aldinger

This U.S. Bureau of Mines report presents an analysis of surface coal mining accidents involving mobile equipment for the years 1989 through 1991. Mobile equipment is defined as haulage trucks, front-end loaders, bulldozers, scrapers, and road graders. These five pieces of mining equipment accounted for 20 pct of all surface coal mine accidents and 41 pct of the fatalities. The general discussion of these accidents covers the accident causes, the primary activity of the accident victims, and other contributing factors. A more detailed analysis of accidents associated with each piece of mobile equipment is also provided. This report will provide mine managers and mine safety personnel with a better understanding of the hazards associated with mobile mining equipment. It identifies where improvements in mobile equipment safety can be made and those areas requiring additional safety emphasis, such as safety training, work procedure changes, or engineering changes to the equipment or work environment. The analysis was performed by a team of researchers using accident data and narratives provided by the Mine Safety and Health Administration.

Jan 1, 1995

By Wilbert J. Huff

For the past 9 years , the technical studies conducted by the Explosives Division of this Bureau have been summarized in a series of reports issued annually . The following account presents investigations undertaken from July 1 , 1943 , to June 30 , 1944. The work is detailed under a number of main headings corresponding to the organizational structure of the Division , the various activities being under the immediate direction of unit chiefs , who report directly to the author . Specific credit , however , is due to the individual unit leader and his assistants .

Jan 1, 1945