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By Larry Mirabelli, David Lilly

In 1777, the French naturalist, Georges Louis Leclerc, Compte de Buffon developed a statistical technique to estimate the width between two parallel lines by randomly throwing a needle at the two lines and counting the number of times the needle intersected one of the two lines. By knowing the length of the needle, the distance between the parallel lines could be estimated. This analysis was named the “Buffon’s Needle Problem”.

Jan 1, 2008

By M. Santillan

Minerales Monclova S.A. de C.V. (MIMOSA) has applied different methane gas drainage technologies, according to the top industry requirements in order to keep the methane gas at the lowest possible concentration in our operations, both in the development sections and longwall sections. Our staff has used the horizontal rotary technique. In 2004 MIMOSA bought a re-built drill machine and signed a contract with Resource Enterprises Inc. (REI), which included a training program in Horizontal Directional Drilling using the reflex system. The training system was developed for a period of three months in Mine VII, with very good performance by the MIMOSA staff. After the training the equipment was moved to Esmeralda Mine, where we had already drilled holes at the development section, 2,500 ft. It was the longest distance that could be reached with our original equipment, obviously; the directional drilling program is another challenge for us and our staff, but we are very confident that our result will be better every time. We will be evaluating each borehole and expect to improve our results in each progressive borehole, until we can drill up to the capacity of the equipment. We are in the process of buying another drill with an electronic monitoring device (DD DMecca) in the following months.

Jan 1, 2009

By R. B. Crookston

Oil shales differ from coals in that they contain less carbonaceous material, convertible to volatile hydrocarbons, and more inorganic rock. In all pre-commercial oil shale development, involving extensive full scale mining operations, there have been no explosions. However, large scale mine tests with oil shale dusts by the Bureau of fines showed that propagating explosions could be induced under certain circumstances. Laboratory tests were conducted on a broad spectrum of oil shale dusts to define chemical properties and to seek correlations with subsequently determined fire and explosivity properties. These latter properties, indicative of safety hazards, increased as the Fischer assay oil yield of the dusts increased and as particle size decreased. Laboratory data were used to relate fire and explosivity properties of oil shales to those of coals and other carbonaceous materials and to assist in the identification and evaluation of potential hazardous situations which may be encountered in oil shale mining and processing.

Jan 1, 1978

By Xing Zhao, Michael A. Sutton, Vikrant Tiwari, Damien Bretall, Xiaomin Deng, William L. Fourney, Uli Leiste

The dynamic response of a thin aluminum plate subjected to both shallow and deeper buried blast loading was studied. Using a combination of high speed stereo-vision and three dimensional digital image correlation (3D-DIC), sequential stereo images acquired every 38.25µs during blast loading were analyzed to determine full-field deformations and plate motions (displacements, velocities and accelerations, effective surface strain and effective surface strain rate). Measurements indicate that the initial sheet deformation was highly localized for both shallow and deeper blast events, with extremely high velocity and acceleration values recorded during the earliest stages of impact loading. Full field strain and strain rate data indicate that well defined strain and strain rate “maxima” are created in the plate, with the potential of affecting the dynamic plate behavior as well as it local failure.

Jan 1, 2010

By Frank M. Vodoklys

This is the final report on Contract H0220049 covering the period from 27 April 1972 to 30 April 1974. The objective of the contract was to develop and evaluate materials and methods to achieve post explosion identification of explosives reliably and economically through the use of phosphor coded grains incorporated into the explosive during its manufacture. A coding system of two spotting phosphors and seven coding phosphors was successfully developed during the execution of the contract. The ability of the coded grains to survive detonation in many different types of explosives was demonstrated and the complete code was extracted from a single 100 micron post-explosion fragment. A method was established for testing grain strength to correlate with field test results and an optical system was designed for extracting the code from the grains. Also in fulfillment of the contract requirements a laboratory method for manufacturing the coded grains was established and ten one-pound samples, each with a different code, were fabricated. Finally, a method was developed for applying a coating of polyethylene to the grains to prevent sensitization of the tagged explosives and the ten one-pound samples were coated and delivered to the Bureau of Mines.

Jan 1, 1974

By Frank G. Miller

Controlling natural-water drives to effect efficient and economic production of petroleum, through wells, from reservoir sands and rocks is a problem of major importance in the oil-producing industry. Water-drive fields are characterized by large quantities of mobile water under high pressure immediately below the oil in the flanks or extraneous parts of reservoir formations, Hence, the water, which is in fluid connection with the oil and a source of a large proportion of the energy available for moving it, advances up-structure to replace it. This phenomenon of water moving crestward into the oil-bearing parts of the reservoir and replacing oil is termed edgewater encroachment. The mechanism by which oil is flushed out and continually replaced by water as the hydocarbon content of the field is depleted must be understood if natural-water drives arc to be used successfully to, induce efficient recovery of oil from its reservoir rocks. Until recently, the function of water in the production of oil has been somewhat obscure and was not given the consideration it deserved in early petroleum production-research programs because of the greater importance associated with and the effort devoted to investigations concerning the relations of natural gas to production of oil. Thus, with virtually no fundamental information at hand, it is not surprising that at first edgewater was considered a necessary evil, and the manner in which it was dealt with depended largely on the experience of the operators. During the intervening years, however, practical information on encroachment of edgewater in oil sands has been widely disseminated as a result of studies of oil-field depletion, and many theories pertaining to petroleum-reservoir energy and performance have been advanced; these theories necessarily included consideration of edgewater as an integral -art of the reservoir fluids and a source of energy for propelling hydrocarbon fluids through the reservoir and to the surface of the ground.

Jan 1, 1941

Rockbursts continue to be a scourge in the mining industry, being responsible for accidents and damage to mining excavations. Although the problem has been present for more than a century, and although much research has been carried out, a solution is still elusive. Determination of, firstly, the demand on the support system imposed in the rockburst and, secondly, the capacity of the support system, cannot be carried out with any confidence, and therefore rockburst support cannot be designed using a conventional design approach. In contrast with the conventional approach, observations of rockburst damage in a mine have revealed a possible alternative approach to rockburst support ? sacrificial support. It was observed, in rockburst events, that a support system consisting of concrete panels restrained by grouted cables was destroyed, and the concrete panels were ejected. However, the rock behind the panels remained apparently undamaged and in place. This behaviour reignited the concept of sacrificial support, conceived more than 20 years ago, and which is described in this paper. The remedial solution implemented on the mine, involving cables wrapped over the panels and retained by grouting into boreholes, has been subjected to rockburst loading and has confirmed the validity of the sacrificial support concept. The concept of sacrificial support may be controversial, but is deliberately presented here with the aim of generating discussions and contributions, and with the ultimate aim of improving safety and reducing rockburst damage in mines. Keywords rockburst, seismicity, seismic waves, rock support, support design.

Jul 1, 2013

By Paul Staples, Paul Messenger, Greg Lane

"Every project is different. While “conventional” SAG and ball mill circuits will suit many projects, for others there are alternatives, which may produce improved outcomes. This paper examines particular examples of recent front end designs which either went against conventional thinking or which employed “out of the box” thinking to realize the desired results.One such example is the design strategy employed for a small capacity gold plant in Victoria, Australia. The selection of HPGR technology for small capacity projects is not generally favoured, given the relatively high cost of small HPGR machines. However, the unusual size distribution of the gold and its liberation characteristics were expected to lead to improved gold recovery offsetting the higher capital cost.Another example is the first large scale application of milling in acid for copper recovery, at a project in south east Asia. The stainless steel, single stage SAG mill using ceramic grinding media was more expensive than a mill constructed of conventional materials. However, the steps of scrubbing, slurrying, grinding and leaching could all be achieved in a single unit operation and the need for thickening and repulping with acid after milling was eliminated.Rod mills were selected for both primary and secondary milling duties for another south east Asian project despite their somewhat outdated reputation. A review of previous industry experience confirmed that rod mills could outperform conventional rod/ball or SAG/ball circuits in cases where the size distribution of the ground product is critical to downstream recovery.These examples are discussed with particular focus on the key drivers in each case."

Jan 1, 2008

By Joshua A. Bennett

"Lawsuits where owners allege their property has been damaged by nearby blasting routinely costblasting companies, explosives engineers, and others in the field both time and money. When ownersfeel the vibration of a blast, they immediately begin to look for damage and usually find cracking thatwas, in fact, present prior to the blasting occurring. When those owners begin to talk to their neighbors and legal counsel, blasting entities suddenly have multiple lawsuits being filed as a result of the same blast."

Jan 1, 2016

By Jack Kadlecik

This final technical report describes the concept feasibility study, testing, design and development effort which went into. The quick opening enclosure access cover and flame path tolerance checking system. A detailed definition of the explosion-proof multiple start threads is shown for two (2) sized electrical enclosures.

Jan 1, 1972

By Jerry C. Tien

In 2009 China mined 2.695 billion metric tones (Gt) of raw coal. It is estimated that only 3-5% or roughly 135 million metric tones (Mt) of these were mined from 300 some surface operations. Except for a dozen or so large modern operations, most of China's surface coal operations are small by western standards, with annual production ranging from a few thousand tones to 300,000 metric tones (mt). Depending on the size of operations, equipment used range from small trucks and shovels to large bucket wheel excavators and draglines in sizable pits. This article provides a brief overview of China's surface mineable coal reserves, mining methods commonly used and increasing environmental concerns; introductions of several large surface operations are also provided.

Jan 1, 2012

By Patrice Favreau, R. F. Ph. D. Professor Emeritus Favreau

After Nobel invented dynamite, blasts were carried out by trial and error, without the use of equations based on the fundamental principles of Chemistry and Physics, although everyone accepted that shock waves were involved; but no equations were available to calculate their intensity. Around 1950 however, M.A. Cook proposed a procedure to calculate the thermochemistry of an explosive, and thus evaluate theenergy released during the explosion of a fully confined explosive. Some blasters then began to use theEnergy Factor; the latter, however, does not subdivide the energy into its three kinds of activities necessaryfor a successful blast, as demonstrated in 1968 by reference 2, namely i) the shock wave which weakensthe rock; ii) the stress field SS which fully fragments the rock; and iii) the release of the stress SS whichcauses the fully fragmented rock to burst out with the velocity necessary to move the rock into the muckpile. The article explains that the way to achieve a successful blast is by insuring that the explosive energy divides properly into the weakening action of the shock wave which is necessary to prevent large collar blocks and toe, and into adequate stress field intensity SS which is necessary to obtain good fragmentation size distribution at the crusher, as well as adequate burst out rock movement to achieve easy mucking.

By Tatiane Suelen Santos Silveira, Dagoberto Santos Brandão, Dalila Chaves Sicupira, Graziele Gianini Braga Maria, Marcos Vinícius Fonseca Ferreira, Daniela Barçante Perasoli

O aço inoxidável duplex combina as propriedades mecânicas da ferrita e a resistência à corrosão da austenita, sendo muito utilizado em aplicações industriais que requerem um bom desempenho. Quando submetido a deformações intensas, a austenita transforma-se parcialmente em martensita, aumentando a resistência do aço. Quando o aço é recozido, essa transformação é revertida e a martensita se transforma em austenita, ocasionando um refino de grão do material. Fases secundárias formadas durante o recozimento podem prejudicar suas propriedades mecânicas e corrosivas. Nesse sentido, o objetivo desse trabalho foi avaliar o efeito da temperatura de recozimento na resistência à corrosão do aço inoxidável duplex UNS S32304 laminado a frio. O aço foi submetido à laminação a frio, com deformação de 60%, e posteriormente recozido nas temperaturas de 600°C, 700°C, 800°C e 900°C por um tempo de 0,5 h. A resistência à corrosão foi estudada através da técnica de polarização potenciodinâmica. A laminação a frio promoveu a formação de martensita induzida por deformação (SIM) e a reversão parcial começou a ser observada após recozimento a 600ºC. A ocorrência de SIM promoveu significativa diminuição do potencial de pite e o aumento da temperatura de recozimento aumentou a resistência à corrosão localizada.

Mar 1, 2019

By Patricio Santis, Jacopo Seccatore

Artisanal and Small-scale Mining (ASM) is a prominent activity in the extractive industry: considering only gold, it produces about 20% of world market supply. Despite this fact, ASM is generally associated with negative aspects of its environmental impact, and operational research is generally neglected. This paper emphasizes the peculiarity of the drilling and blasting systems of small underground mines in selected South American Countries. Such Countries, while having large mineral deposits and well recognized large-scale mining activities, at the same time still present on their territory ASM activities that are archaic, highly inefficient and dangerous for the safety of its operators. This paper documents drilling and blasting activities from gold mining in Ecuador and Chile. First, are described the outdated and often non-rational techniques employed by miners, to provide a general framework of the current methods. Then, it is shown what can be improved and how the current methods can be modified. Finally, are shown some field applications and the comparisons of the results obtained. One case shows how blast pull efficiency can be increased of from 82% to 98% by changing non-rational applications of explosive products. Another case shows how, by rationalizing blast designs, drilling and blasting costs can be reduced by 9% per month, the advance by blasting increased by 29% and the blasting efficiency increased from 70% to 90%. Finally, it is concluded that examples of application show how operational improvements are easily applicable on the field, relying only on tools and resources of artisanal mining, but combining solid engineering bases with confidence-gain and respect for the experience of the miners.

Sandsloot open pit is situated on the northern limb of the Bushveld Complex, 250 km north east of Johannesburg, South Africa. Sandsloot is currently the largest open pit platinum mine in the world and is one of six potential open pits in the area. The geotechnical strength properties of the Platreef have posed significant mining and processing challenges to the PPRust operation since inception in 1992. In order to optimize the whole business as opposed to isolated cost centres a mine to mill initiative was embarked upon in 1997. Initial work focused on ore characterization and an entire suite of data was collected for each rock type. This included mineralogy, geochemistry, geotechnical, blast ability indices, as well as metallurgical strength data. The second phase involved the clear definition of customer requirements, namely the optimum performance criteria for the plant and mining departments. This involved extensive field trials and data capture to measure the interaction and influence of the mine to mill value chain. Once the design targets were defined, a 3D geotechnical model was constructed to ensure that the targets were consistently achieved. The model is very similar to an ore reserve model; however, it is populated with geotechnical, metallurgical and blast index data. Through software queries the appropriate blast powder factor for each mining block can be obtained, thereby ensuring the correct fragmentation is blasted for the plant and mining operation. The initiative has delivered significant results showing improvements across the mine to mill value chain. These include increased loading rates, reduced electricity and crushing consumables, as well as higher plant throughput. Additionally, the initiative has benefited both brownfield and greenfield projects on the PPRust operation

Jan 1, 2006

By Dale S. Preece, Stephen H. Chung

Electronic detonators and the attendant precise detonation timing that they facilitate are having a measurable effect on rock blasting in terms of improved fragmentation and vibration control. These improvements are increasingly well documented which is driving the expanding use of electronic detonators. In spite of the growing body of positive evidence concerning the benefits of precise delay timing, very little work has been done to document the impact of electronic detonators on the movement of rock. In this study 3-D computer programs, used to predict blasting induced rock heave, including the effects of detonation timing, are used to simulate the effect of precise timing on rock movement. Implementation includes quick, precise timing between blastholes going down a row and then much longer delays between rows of blastholes. For example an effective blast design might call for precise 3 ms delays between blastholes along a row and then 60 or 72 ms between rows. Several options are studied in this paper using computer simulations to draw some conclusions about the underlying physics affecting the process and how precise timing might have a positive impact on blasting induced rock motion.

Jan 1, 2005

By Leroy O. Gieseke, John B. Begley

If the particles produced and transported in your plant are as chunky as rough crushed coal or as fine as cement, there are probably several conveying and elevating systems suitable for your operation. The problem is deciding which is most suitable in terms of space, energy cost, allowable product degradation, productivity, and angle of movement. Each conveying and elevating method should be fit to the products it can handle successfully, to desirable economics, and to suitability for the overall operating scheme. Matching along these lines will result in selection guides that should be useful for many years, although design evolution is expected for the materials handling equipment involved. There are several common bulk material handling devices for moving solids: belt conveyors, screw conveyors, bucket elevators, chain conveyors, and en-masse conveyors/ elevators. En-masse conveyor/elevator equipment is commonly compared and contrasted with the other devices. These comparisons often involve en-masse versus all others. En-masse has developed into a versatile technique because the machines can move materials horizontally, vertically, or in closed circuit. Such machines unload, elevate, store, reclaim, and distribute materials-all without ancillary equipment except for chutes and gates. Bulk material can be carried, as with a belt conveyor or bucket elevator; pushed, as with a flight or screw conveyor; bumped, as with a vibrating conveyor; blown, as with a pneumatic conveyor; fluidized, as with a dense phase pneumatic conveyor; or by applying internal forces to it to induce "en-masse" flow. Conveying en-masse is analogous to the flow of a fluid in an open channel, and elevating en-masse is analogous to the flow of fluid in a pipe. In the case of a fluid, flow is caused by a differential in pressure. With en-masse movement, flow results from resistance to shear induced by the movement of chain and flights.

Jan 12, 1980

By S A. Myers, T Klein

The Yanacocha mining district is located in the northern Andes of Peru. The project is within the Cajamarca province, 20 km north of the town of Cajamarca and 600 km north of Lima, the capital of Peru (Figure 1). The district encompasses an area of 120 km 2 and is centred on the 78030'west longitude and 7000' south latitude. The project lies at an elevation of 3400 to 4200 masl.

Jan 1, 1999

By A. Davis, C. Webb, J. Sorensen

The abandoned Belle Eldridge Mine near Deadwood, South Dakota, is on land controlled by the U.S. Bureau of Land Management (BLM). The mine produced lead and zinc during the first half of the 1900s. Because of acidic drainage and elevated levels of metals in tailings and waste rock, the site was evaluated in 1998 and 1999. After evaluation, the mine was remediated during 1999-2001 by the BLM. Since remediation, values of pH in water samples have been nearly neutral and specific conductance values have been much lower than before remediation. The Grizzly Gulch forest fire of July, 2002, consumed much of the Belle Eldridge site and resulted in greater than normal erosion and sediment flushing during the months following the wildfire. Had the site not been remediated and the tailings emplaced within a capped repository, generation of acidity and off-site migration of heavy metals within sediments could have been severe at downstream locations.

Jan 1, 2007

By W. P. Yant

This report describes result of a study of the carbon monoxide and particulate matter in the air of the Holland, Tunnel and metropolitan New York made by the Bureau of Mines (which had participated in the development

Jan 1, 1941