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By Hani Henein

Recent innovations in atomization of molten metals have occurred in the area of single fluid atomization. Impulse Atomization (IA), one of the single fluid techniques, provides unique capabilities to study different regimes of atomization in a controlled environment. By changing processing variables, a mono-dispersed distribution of droplets above one millimeter in diameter can be produced. This is accomplished through proper characterization of the forces influencing the process and in particular the flow of melt through the orifice. This paper will discuss the approach and illustrate results with molten aluminum and cobalt.

Jan 1, 2006

By Wilfried Ufer

[1. Einführung in die Problematik 1.1 Die Bedeutung des Schildausbaus Seit fast 30 Jahren ist die Konkurrenzsituation auf dem Primärenergiemarkt der Bundesrepublik Deutschland durch einen von Erdöl and Erdgas geführten and insbesondere gegen die Steinkohle gerichteten Verdrängungswettbewerb gekennzeichnet, der den Steinkohlenbergbau zu tiefgreifenden RationalisierungsmaBnahmen zwang. In diesem Zusammenhang kam es Anfang der 70er Jahre zur Einrührung des Schildausbaus, der eine erhebliche Produktivitätssteigerung in den Strebbetrieben zur Folge hatte and damit die Uberlebenschance des Steinkohlenbergbaus in der Bundesrepublik Deutschland enorm verbesserte. Der Grund hierfdr lag darin, daB der Schildausbau im Vergleich zu dem vor ihm eingesetzten Rahmen- and Einzelstempelausbau eine wesentlich hdöhere Ausbauleistung erbrachte, weil er sich weit weniger empfindlich gegen Hangendausbruche and aus dem Alten Mann hereinbdschende Bruchberge erwies. So erklärt sich auch die stürmische Entwicklung and die schnelle Verbreitung des Schildausbaus. Bereits 1975 stammte rd. 50 % der Fdrderung aus Schildstreben, 1990 waren es fiber 75 % and heute sind es fiber 90 %. 1.2 Die Staubentstehung beim Schildausbau Die Erfolge des Schildausbaus sind unbestritten. Jedoch nahmen :nit seiner Einführung die Probleme der Staubentstehung and Staubbekämpfung im Vergleich zum Ein zelstempel- and Rahmenausbau erheblich zu. MaBgebend dafür sind hauptsächlich folgende Gründe: - Abbau von dozen nit gebrächen, weichen Hangendschichten, die erst durch Schildausbau abbaubar wurden, - Zerkleinerung des auf den breiten Kappen aufliegenden Bergematerials infolge der höheren Ausbaustiltzkrafte des Schildausbaus, Zermahlen der sick in die Spaltabdichtungen hineinarbeitenden Bergestückchen, - Erhöhung der Wettergeschwindigkeit infolge der durch die Baufarm des Schildausbaus bedingter. Verkleinerung des Strebquerschnitts verbunden mit der Aufwirbelung and Aussichtung von Staub, - Aufwirbelung von bereits abgelagertem Staub im Bruchraum beim Hereinbrechen der Dachschichten. Die genannten Gründe treten zumeist nicht in jedem Abbaubetrieb gleichzeitig auf. Sie rind vielmehr u.a. abhängig vom Ausbautyp, von den Gebirgsverhältnissen and von der Abbaugeschwindigkeit. Trotzdem ergeben sich beim Vorrücken des Ausbaus in der Regel hohe Staubkonzentrationen, die deswegen besonders kritisch sind, weil es sich um quarzhaltigen Feinstaub handelt, der besonders gesundheitsschädlich ist. Die Hauptzutrittsstelien]

Jan 1, 1984

By J B. Gemmell, D R. Cooke

Recent mapping at the Kelian epithermal gold deposit in East Kalimantan, Indonesia has delineated intrusive and extrusive-phreatomagmatic breccias, their magmatic roots, and late-stage endogenous domes of a maar-diatreme complex. The Kelian epithermal system is characterised by a wide variety of mineralised and unmineralised breccias, which include tectonic, hydrothermal, phreatic and phreatomagmatic varieties. Phreatomagmatic breccias and associated igneous rocks post-date early stage alteration and mineralisation, and pre-date main stage precious and base-metal mineralisation. This study emphasises the spatial, temporal and genetic links that have been drawn between diatremes and both epithermal and porphyry systems in volcano-plutonic arcs.

Jan 1, 1999

By R. J. Jewell

The storage capacity of any given tailings storage facility (TSF) is a function of the volume available for the tailings, for which the geometry of the final upper surface of the tailings is most important. One of the advantages that can be obtained from thickening tailings prior to discharge is that the tailings can be stacked at a steeper beach angle than is obtainable with conventional low-density slurries. However, there is at present no universally accepted method available for the accurate prediction of tailings beach slopes. This paper examines the current situation with the objective of putting the quest for a method for the accurate prediction of beach slopes into perspective. The paper references published reviews of the best-known beach slope prediction methods. However, there do not appear to be any independently verified projects or published references to projects on which a Class A prediction has been validated for any of these approaches, and in those instances where projects have been implemented correlation of actual with predicted slopes has been poor - often due to differences between the properties of the tailings assumed in the design and those actually achieved in the field. The author also concludes that flume-scale testing cannot be taken as a reliable indicator of full-scale performance, and suggests that the outcome of any current predictive method should be used by experienced practitioners as only one of a range of indicators in order to suggest a range of slope angles likely to result for any given operation. Practice has shown that it is possible to manipulate beach slopes by changes to the disposal technique, such as limiting the rate of discharge per discharge point and by increasing or decreasing yield stress, but the impact of these changes cannot readily be predicted. There are also newly emerging technologies, such as the injection of a polymer into the tailings at discharge, that will enhance the dewatering of tailings and hence expedite the consolidation of the tailings, that could well facilitate the development of steeper beach slopes. The overall conclusion is that with the current state of knowledge, the accurate prediction of beach slopes is not possible. Furthermore, in view of the inherent variability of the tailings parameters from any operation, it may well be of more value to concentrate on developing an understanding of the means by which the tailings parameters may be manipulated by the operators to achieve a given beach slope than to concentrate wholly on developing a generic beach slope prediction model.

Jan 1, 2012

By E. Sun

Tailings disposal is a significant consideration for the mining industry, with the majority of the ore processed in most mining operations ending up as tailings. Several tailings dam failure accidents have occurred during the past few years and mine tailings dam failures are occurring at relatively high rates. Tailings dam failure is disastrous with the serious damage and the loss of lives. To increase the tailings dam safety, a tailings dam monitoring and pre-alarm system (TDMPAS) based on the internet of things and cloud computing platform has been accomplished with the abilities of real-time monitoring of the saturated line, impounded water level, rain fall and the dam deformations etc. The TDMPAS has been applied in several mines in China and helped the mine engineers monitor the tailings dam safety and get warning information automatically and remotely in any kind of weather conditions. This work has been demonstrated the tailings dam monitoring and pre-alarm system (TDMPAS) is meaningful to monitor the tailings dam physical safety condition. The TDMPAS could be applied to monitor all the national tailings dams online in the future.

Jan 1, 2012

By Z. Saw, C. Poveda, N. L. Mai

Optimising the throughput of a mining network comprising all equipment from shovels to semi-autogenous grinding (SAG) mills is a complicated task, yet the potential benefits can be significant. Key modelling challenges stem from the sheer number of possible routes which material can travel, different equipment operating under different constraints, and the rate of SAG mills being calculated through a nonlinear function of the blended materials’ rock attributes. Nevertheless, this is an ideal onapplication area of mathematical programming, a branch of operations research. This paper describes an application of mixed integer linear programming (MILP) to optimise the mining equipment network of one of the world’s largest copper mines.The model takes as input a year-long monthly mine schedule of shovels in different pits, pushbacks, sequences and faces which produce material to be moved through a network of crushers, conveyors, silos, distributors, stockpiles and SAG mills, ultimately outputting a daily operational plan for all equipment that maximises the throughput of the network. All operational constraints and business rules are considered, including three quality attributes of copper ore. Comparing model results with actual data shows an improvement of 4.47% in network throughput tonnage. Additionally, although the model is solved using a free, open-source solver, optimal solutions are still achieved within a practical timeframe.

Sep 1, 2021

By R. F. Balazik

By March 2001, shrinking global markets, reduced consumer spending and declines in domestic manufacturing and industrial output ended the longest economic expansion in US history and pushed the nation’s economy into its first recession in a decade. Aggravated by the terrorist attacks of Sept. 11, the recession led to large reductions in the domestic production of processed mineral materials. Some of the most significant production declines in the US metals industry were registered by aluminum, copper and steel producers. They faced strong foreign competition, higher energy costs and lower prices for their products. However, homebuilding and other domestic construction sectors — major users of nonmetallic mineral products such as cement, brick, glass and stone — remained strong enough to help raise the output of industrial mineral materials slightly above previous year levels. A strong US dollar continued to weaken the competitive stance of US metal and nonmetallic mineral materials companies alike against foreign producers in markets at home and abroad.

Jan 1, 2002

By P. D?Elia

Following a study by NIOSH on the availability of teams in the U.S. as well as existing training sites and their capabilities, the Penn State University, leaders of the Pittsburgh Section of SME, providers of mine rescue equipment, and industry sponsors united to establish and make fully functional a student mine rescue team at Penn State University. With the growth of MERD and mine rescue competitive events at Missouri S&T, the Mine Training and Technology Center in PA, and at Colorado School of Mines Edgar Mine, a critical mass of effective training venues were made available to help student teams progress and develop mine rescue skills. The challenges to be met in creating and developing a student mine rescue team will be discussed. The rewards from this type of effort will be the quick capability of graduates from mining engineering programs to be involved in not only mining operations, but industry mine rescue teams and other leadership roles as well.

Jan 1, 2012

By M. Rice, M. Stanley, J. Marlow

Arizona construction aggregate industry remains in the crosshairs of public debate, caught between the need for aggregate-based building materials and alternative, high-value land-uses. To better manage lands and improve land-use decisions, the Arizona State Land Department has need for a system to assess potential aggregate resources on State Trust lands, and assign dollar values accordingly. Thereafter aggregate values can be compared to residential, commercial, agricultural, recreational, and habitat values -- in a determination of highest and best land-use.

Jan 1, 2002

By Gloria Fernández

La contaminación por drenaje ácido de mina se considera como la responsabilidad ambiental y económica más grande que actualmente enfrenta la industria minera. En ese sentido, se delimita las áreas afectadas mediante la perforación de pozos de monitoreo a través de un estudio geofísico previo. Por ello, el presente trabajo señala los métodos geofísicos como herramientas que pueden ayudar a delimitar y mapear las zonas afectadas por la contaminación proveniente de drenaje y filtraciones que va desde canchas de relave, pilas de lixiviación a minas abandonadas, etc.

Aug 25, 2002

By George D. Dub

The Bureau of Mines, in connection with the investigations of war minerals it conducted, examined the graphite deposits of this country, studied the methods of mining and preparation used, and sought to devise more efficient methods for the preparation of domestic graphite, and to standardize the quality of the product. The graphite investigations covered three general phases, as follows: 1. An examination of the deposits in Alabama and other States, and a survey of the methods of mining and preparation used. In this connection methods of sampling and analysis were noted and experiments made to determine a standard method of sampling and a, rapid but accurate method of analysis. 2. Experimental work on the concentration and refining of domestic crucible graphite to improve the quality of the product and to lessen waste. 3. Experimental work in crucible manufacture to determine the properties of domestic flake and the maximum proportions that might be used without impairing the quality of the crucibles. This work was accompanied by photomicrographic study of crucible structure.

Jan 1, 1920

By M A. Lund, C D. McCullough

In Australia and worldwide, open cut mining has become increasingly common over the last few decades through changes in excavation technology and ore economics. However, such operations frequently leave a legacy of open mine pits once mining ceases. Pit lakes will then form in mine pits that extend below the water table when dewatering operations cease. Pit lake waters are typically contaminated with metals, metalloids, saline or acidic/alkaline and rarely approach natural water body chemistry. Physically, pit lakes have unique bathymetries, are often strongly wind sheltered and have very small catchments. Nevertheless, pit lake waters often constitute a vast resource but of limited beneficial use (due to water quality issues); with a potential to contaminate regional surface and ground water resources. Water in pit lakes has the potential to be useful for a range of purposes in the Australian context of characteristic hot, dry climate and relatively few natural water bodies. Consequently, pit lakes can be seen to represent either a significant liability or a water resource to mining companies and regional communities. However, the lack of knowledge on pit lakes continues to hinder their proper management. This paper summarises the limited information currently available on water quality associated with Australian pit lakes. Information on pit lake occurrence, distribution and water quantity and quality is not nationally collated and requires immediate and ongoing attention from both mining companies and regulating authorities. Lack of a readily available database for pit lake occurrence, distribution and water quality fails to realise the potential for these water resources by both mining companies and Australian communities. Lack of access to pit lake quantity and water quality data may also lead to failure to manage this significant source of mining environmental risk.

Jan 1, 2009

By Joseph J. Feiler

Fires in underground coal mines are persistent problems anywhere in the world that coal is mined. Coal fires pose safety and health hazards in the form of mine subsidence, loss of energy reserves, destruction of property and surface improvements, and air pollution. In 1995, the US Bureau of Mines (US-BM), in cooperation with the Colorado Division of Minerals and Geology (CDMG),entered into a contract with Goodson & Associates Inc. (GAI) to design and field test the effectiveness of a new foamed grout technology called ThermoCell. GAI is a Lakewood, CO geotechnical and mining reclamation engineering firm. The company developed ThermoCell to control and extinguish underground coal fires. The viability of the special grout and the technology of application were established during a full-scale field demonstration at the abandoned IHI Coal Mine fire, near Rifle, CO. Following acquisition of additional funding by CDMG in 1999, Goodson returned to the site in April to continue the grouting to fully extinguish the IHI fire.

Jan 1, 2000

By D. H. Platt

Gypsum and gypsite, used in the manufacture of plaster and plaster products, have been mined from deposits near Acme, Hardeman County, Tex., for more than 30 years. The Certain-toed Products Corp., 120 East Lancaster St., Ardmore, Pa., operates the Acme, Tex., mine. Underground hauling was done with storage-battery and Diesel-electric-powered shuttle cars. Many mining companies and individuals have manifested interest in all types of equipment powered by Diesel or Diesel-electric units, as attested by the recent increase in use of Diesel-powered equipment in underground metal and nonmetal mines. The purpose of this paper is to describe the manner in which a storage battery-powered Joy Model 60D2 shuttle car was converted to Diesel-electric power. The conversion was made, at the instance of the operating company, by Stewart & Stevens on Services, 4801 Lemon Ave., Dallas, Tex. This is believed to be the only such converted shuttle car in use.

Jan 1, 1950

By A. T. Sweet, G. Douglas Gardner

"INTRODUCTION In the ammonium sulfate process for the production of alumina from clay,,3/ the clay is baked with amonium sulfate at about 400ºC. to form anhydrous ammonium alum and free ammonia or ammonium carbonate. The alum is leached from the baked product with water and circulating liquors and is purified by recrystallization. Aluminum hydroxide is precipitated by treating thus alum the alum the ammonia or ammonium carbonate from the baking step. Ammonium sulfate is recovered from the filtrate for reuse, and the aluminum hydroxide precipitate is calcined to produce high-purity alumina. In this process, as in other acid processes for the production of alumina, 4/ a large part of the iron in the clay is extracted. The iron tends to build up in the leach liquors and contaminate the crystals, so that its elimination is one of the most important problems in the process. A number of large clay deposits occur in the Western States. Those that have boon explored most extensively 5/contain an average of 24 to 30 percent available A12O3 and 2 to 8 percent available Fe2O3. 6/ The available Fe2O3 content of various other clays ranges from less than I percent to more than 20 percent. The available Al2O3 or Fe2O3 is usually 90 to 98 percent of the total but may be much less. In generals the iron content bears no fixed relation to the alumina content and may vary widely within a given deposit."

Jan 1, 1948

By Dean Bray

During the past three years, a new rear-dumping dragline bucket technology has been patented, developed and tested at North Dakota coal mines. Field testing has shown that this new concept in dragline bucket technology can improve strip-mining efficiencies by reducing cycletimes and increasing dumping radius. This article details the process, participants and the results for the development of a rear-dumping dragline bucket. Participants in the process In November 1995, the board of directors of Dakota Coal authorized the execution of a field test and option agreement and a license agreement with the partnership of D.F. Schmidt, electrical/maintenance supervisor, and Bill Lengenfelder, president of Modern Industrial. The board also authorized entering into a dragline bucket field-testing agreement with the Falkirk Mining Co.

Jan 1, 1999

By Gang Chen

Conventional methods designate a factor of safety, a deterministic number, to indicate the stability of a mine excavation. However, this deterministic description of excavation stability is frequently insufficient or inaccurate and, sometimes, misleading. Employing the probabilistic analysis to determine the likelihood of mine excavation failures will lead to a better understanding of ground control problems and result in more rigorous designs of the excavations. Based on the theory of probability, two approaches are taken in this study for the probabilistic analysis of excavation stability. The first one utilizes direct integrations for the estimation of failure probabilities of mine excavations. Due to the complexity of the integration, this approach can only be applied to solve relatively simple problems. In order to overcome the limitation of the direct integration method, the second approach employs the first-order second-moment approximation of the failure probabilities for more complex ground control problems. The probabilistic analysis offers a deeper insight into the uncertainty associated with the stability of mine excavations. The study indicates that the distributions of parameter values play a significant role in the mine excavation stability, which can not be disclosed by the conventional methods of stability analysis. Greater dispersiveness of the parameter values will lead to a different probability of failure, although the factor of safety estimated by conventional methods stays the same if the mean values of the parameters are constant. By taking consideration of the probabilistic distributions of the parameters, the probability model can provide more reliable designs of mine excavations.

Jan 1, 1996

By H. O. Hofman

WHEN dry chlorine gas is made to act in the cold upon finely¬divided gold,' it converts the latter with evolution of heat into auro-auric chloride, Au2CI4, a hard, dark-red, hygroscopic salt. Moisture splits this salt into aurous and aerie chloride, Au2C14 = AuCI + AuCI3; treatment with water converts it into auric chloride and gold, 3 Au2CI4 = 4 AuC13 + Au,. Aurous chloride, when stirred with water, undergoes a similar decomposition, 3 AuCI = AuCI3 + Au,. These decompositions of auro-auric chloride and of aurous chloride furnish the explanation for the practice of moistening an ore before it is treated by the Plattner chlorination-process; practical experience having shown that gaseous chlorine gave an unsatisfactory extraction with dry ore. According to Rose,' fine gold is acted upon more slowly by chlorine than gold containing some base metal, e.g., copper. He also states that small quantities of silver increase the rate of solution, but adds that the coating of silver chloride formed checks, and finally stops, further action, if the percentage of silver be increased beyond a certain undetermined amount. Bromine' acts upon finely-divided gold in a manner similar to chlorine; the auro-auric bromide, Au2Br4, however, is not hygroscopic. Upon treatment with water it is decomposed as is the corresponding chlorine salt. It is generally believed that bromine does not act as energetically upon gold as does chlorine. This seems to be borne out by the results in the leach-

Mar 1, 1905

By Edwards A. B

The following note on the mineral association in the ores of the Tennant Creek Goldfield, Northern Territory, is largely based on Mineragraphic Reports Nos. 49, 89, 117 and 193 of the Council for Scientific and Industrial Research. These reports are the results of the examinations of auriferous specimens from a number of mines of the goldfield and are now supplemented by the examination of further specimens from Mt. Samuel forwarded by Mr. V. G. Martin.The Tennant Creek Goldfield lies in the central portion of the Northern Territory, about Lat. 190 35', Long. 1340 15', on the Overland Telegraph Line and about 369 miles north of Alice Springs. It comprise an area extending about 50 miles east and west, by 30 miles north and south.The geology of the goldfield has been described by Woolnough. (2)The rocks of the area are of pre-Cambrian age, and consist of talcose, chloritic, micaceous and siliceous schists of sedimentary origin, interbedded with flows or dykes of schistose quartz porphyry, and of granites which were intruded subsequent to the regional metarporphism of the area. The rocks are moderately folded, but the beclding tends to be obscured by a pronounced east-west cleavage. The most continuous orebodies run east and west, parallel with this cleavage.Numerous lenses of hematite occur in the schists, with their long axes, parallel to the cleavage, and the gold values of the field are frequently associated with such hematite bodies. The dimensions of these hematite bodies are variable but rarely exceed a length of 300 ft., with an average thickness between 10 and 30 ft.; the original vertical dimensions are thought to be comparable with their length. The lenses tend to occur in groups when they are arranged en echelon both horizontally and in depth; and erosion has exposed individual lenses to different degrees, ranging from incipient exposure to complete removal. The existence of unexposed hematite lenses at depth has been proved by geophysical surveys, coupled with drilling tests. (3)A few of the bodies are pipe-like. Many are surrounded by a casing of brecciated rock, composed of fragments of hematite and shattered country rock, and presumably caused by subsequent earth movements which crushed the country rock against the resistant hematite bodies. In the early days of the field most of the important gold occurences were found within these crushed zones, or, to a less extent, within the hematite bodies themselves.These occurrences appeared to be associated only with those hematite lenses which were intersected by quartz veins or other lines of weakness, of later origin than the crushing. This led Woolnough to think that the introduction of the gold and attendant bismuth was subsequent to the...

Jan 1, 1942

By Moinpour M

The kinetics of reduction of copper (cuprous) sulphide with CO-CO2-He gas mixtures, using an excess of CaO(s) as a sulphur-scavenging substance were investigated in the temperature range 855° - 950°C by a thermogravimetric method. Several gas compositions were employed at each temperature. Potential carbon deposition was overcome by preheating the reducing gas mixture. The phase-composition and the morphology of partially reactedsamples were analysed by a SEMlEDAX unit. The reduction rates showed strong dependence on the bulk gas compositions (CO, CO2) and, in most cases, the rate declined with rising temperature. The rate-controlling step appears to be the diffusion of CO2 gaseous species through the micropores of the CaS(s) - product layer which builds up around the CaOcore.

Jan 1, 1989