Search Documents

By Michael J. Pazuchanics

This report documents the current status of the U.S. Bureau of Mines ongoing investigation of the use of adaptive signal discrimination (ASD) systems to distinguish between cutting coal and cutting rock. Cutting-tool forces and vibrations were measured in the laboratory using both conical bits and roller cutters in a linear-cutting apparatus for several material samples and two cutting directions. A number of ASD systems consisting of one or more signal classifiers were trained and tested to study how data window size, type of signal feature, and combining (polling) of classifier results influence system performance. The results show that ASD system recognition rates can be improved by increasing data window size, removing air-cutting portions from the signal data, overlapping data windows, and combining (fusing) information at various levels of ASD system operation.

Jan 1, 2010

By Steve Kral

President Bush’s National Energy Program and his Clear Skies Initiative both emphasize the use of coal to help meet the nation’s growing energy needs. And why not? Coal is currently responsible for more than 50 percent of the nation’s electricity generation. That fact, though, seems to be lost on policy makers, the environmental community and the public. Critics of coal advocate the increased use of renewable energy sources and the increased use of natural gas. Renewables, though, are only capable of generating a tiny fraction of the power required. Natural gas is expensive. And natural gas production cannot keep up with demand, especially given the nation’s increasing energy needs.

Jan 1, 2003

By Steve Kral

When the price of gold cracked the US$9.60/g(US$300/oz) mark last year, the gold-mining industry began to crank up again. This followed several years of gold prices that had languished in the mid-200s. Existing mines increased production and mines that had lain dormant for many years were getting second looks. The United States still produces a large amount of gold. But not much of the new production is coming from that country. Instead, strict environmental regulations still have companies wary of trying to invest the millions needed to start a new mine or expand existing ones. And after years of studies and negotiations between legislators, environmental interests and the mining industry, the United States still has not crafted a new mining law.

Jan 1, 2003

By Steve Kral

Worker safety is an issue that transcends industries, whether it be mining, construction, manufacturing or even general office work. In the mining industry, safety and training are particularly important because mining is a dangerous occupation. Throughout the years, federal and state safety regulations have been written and revised to keep up with the changing technologies. And mine operators have installed their own safety and training programs. They have come to realize that a safe and healthy workforce has positive effects on productivity and profitability —not to mention avoiding the high costs of injury-related absenteeism.

Jan 1, 2003

By Martín E. Mendoza

En 2010 se identificó un peligro potencial en la pared Norte del Tajo Chaquicocha, donde existía fallas pre-existentes, catch bench reducidos (subestándar) y bloques colgados que presuponían condiciones de mala voladura de control. Por ello, se planteó la modificación del diseño Final del Tajo Chaquicocha, ya que la continuidad de estos malos resultados arriesgaba el minado de los Bancos inferiores. En ese sentido, el objetivo del presente texto estriba en lograr voladuras masivas, sin afectar la estabilidad de las paredes del Tajo Chaquicocha, así como tener beneficios económicos en la reducción de tiempo de minado por cada banco, y en la productividad (Dig Rate) de los equipos de carguío.

Sep 12, 2011

By K. Bartholomew

The Functional Performance Equation for ball milling circuits provides plant staff with a new means to improve circuit performance. However, successful execution of a plant processing performance improvement project, with verifiable improvements, requires a significant number of accompanying steps beyond using this equation. In order to identify and articulate all these steps, a study was undertaken with the metallurgical staff from two milling operations and process application specialists from a grinding media manufacturing company. “Task analysis” of improving plant grinding performance was carried out. This analysis identified the required steps, and ultimately yielded a “Plant Grinding Circuit Processing Performance Management/ Improvement System.

Jan 1, 2015

By Paul J. Sylvester, Yeonuk Choi, Mike Nelson, Louis J. Cabri, Mike Tubrett

"The development and characterization of sulphide standards containing as many as seven precious metals has increased the efficiency and comprehensiveness of micro-analyses for deportment studies using laser ablation microprobe inductively coupled plasma mass spectrometry (LAM-ICPMS). Because trace precious metals occurring in solid solution or as sub-micron inclusions in sulphides, arsenides, and sulpharsenides are often heterogeneously distributed, a significantly large number of analyses are required. Using well-prepared samples it is possible for up to 120 analyses per day, far more than by other comparable methods. Examples will be discussed from projects focused on the deportment of Au and the platinum group elements (PGE).INTRODUCTIONBecause gold and the platinum-group elements (PGE) occur as both discrete minerals and in trace quantities in a variety of minerals (mostly sulphide, arsenide, and sulpharsenide minerals), specialized trace analytical methods were developed and applied to determine the deportment of precious metals in ore deposits, requiring sensitivities ranging originally from about hundreds to presently tens of ppb for individual precious metal or less.In mineralogical studies, micro-analytical techniques such as the electron microprobe were first applied to obtain analyses for major elements in about 1959-60, but as the instrumentation improved early attempts for PGE in potential carrier minerals indicated that reasonable levels of detection (LOD) were of the order of 300-400 ppm, depending on analytical conditions, X-ray spectral lines, and mineral matrix (e.g., Cabri and Laflamme, 1976). Eventually, the lowest detection levels by electron probe micro-analyses (EPMA) obtained for some PGE were of the order of 10s of ppm using high accelerating voltage and current for extended measuring time on peak and background (Gervilla, Cabri, Kojonen, Oberthür, Weiser, Johanson, Sie, Campbell, Teesdale and Laflamme, 2004)."

Jan 1, 2010

By L. C. IlsLey

Explosives have been fired electrically for several decades. Mountains have been tunneled, deep shafts sunk, extensive coal and metal mine workings excavated and, in times of war, railroads, buildings, bridges, and fortifications have been destroyed by means of electrically fired explosives. Modern engineering depends so much on explosives that their safe and efficient handling and especially their detonation are of prime importance to all those connected with the use of explosive agents. Electric shot-firing is only one method of igniting explosives, but it is rapidly spreading and because of certain inherent safety features should be encouraged. Data collected by the Bureau of Mines indicate that in the United States a large percentage of the blasting in quarries, shafts, and tunnels, and from 15 to 25 per cent of the blasts in mining operations, are set off electrically. The Bureau of Mines is interested in electric shot-firing because of its use in mining, and especially because electric methods, when properly applied, are undoubtedly safer than other methods commonly used.

Jan 1, 1926

By X Hu, C-C Yang, J Pan

In this work, preheating and roasting tests of pellets made from blends of Western Australia ultra-fine (WAU) magnetite concentrate and Chinese domestic magnetite concentrate or Brazilian hematite concentrate were carried out. The results showed that pellets made from 100 per cent WAU magnetite concentrate possesses inferior preheating and roasting performance when preheating at 1050°C for 20 minutes and roasting at 1300°C for 40 minutes, the compressive strength of preheated and fired pellets is 502 N/pellet and 2313 N/pellet, respectively. When 40 per cent Chinese domestic magnetite concentrate or 20 per cent Brazilian hematite concentrate was blended with 60 per cent or 80 per cent WAU magnetite concentrate, the appropriate preheating temperature of the pellets are reduced from 1050°C to 950°C and 975°C, and also the firing temperature of two types pellets are decreased from 1300°C to 1250°C and 1280°C respectively. Moreover, the compressive strength of fired pellets is obviously improved up to 2746 N/pellet and 2630 N/pellet respectively. Microstructure analysis of the fired pellets made from 100 per cent WAU shows its poor growth of Fe2O3 grains, low interlinkage degree of hematite grains, small size of crystallised grains and high porosity of pellet; however, the fired pellets that blended with domestic magnetite concentrate or with Brazilian hematite concentrate have fully growth of Fe2O3 grains, closer interlinkage of hematite grains, lower porosity and stronger consolidation. The preheating and roasting performance of WAU magnetite concentrate pellets can be improved by optimising ore matching.CITATION:Pan, J, Hu, X, Zhu, D-Q and Yang, C-C, 2017. Pelletising performance of Western Australian ultra-fine magnetite concentrate and strengthening technique by optimising ore matching, in Proceedings Iron Ore 2017, pp 97–104 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By N. A. White

Whereas the ultimate world supply of energy minerals-defined as fossil fuels and fissile materials - is controlled by geological factors, the actual supply at any particular time is controlled by economic feasibility, technological innovations and /or political decisions. This paper identifies and discusses the principal uncertainties surrounding the international availability of energy minerals from now until the end of the century. A brief comparison is also made between energy and non-energy minerals. Genuine shortage s of energy minerals are now of a very long-term nature, whereas artificial ones may occur at any time and have a serious effect on the world economy due to the dependence of most OECD countries on imports of energy mineral . This paper argues that events over the last decade, such as the demand for a New International Economic Order, the OPEC increase in crude oil prices and the growing international lobby on environmental issues especially relating to nuclear safety - will progressively lead to a major, long-lasting transformation of the energy scene world wide. This transformation will encompass demand, in terms of conservation and efficiency, the supply mix of the various energy minerals , the supply system and the structure of the different energy industries . It is already affecting the role of governments and reaching into the question of national sovereignty both of developed countries, such as the U.K., Norway and Australia, and the developing countries, thereby making energy minerals a key area of international relations.

Jan 1, 1978

Comparison of Industrial Cyanide Destruction Processes

Sep 13, 2010

By Stephen L. Chryssoulis, Stamen Dimov

"Preg-robbing has been known for many years, where increased losses are suffered because dissolved gold is removed from solution by adsorption onto carbonaceous matter. In direct cyanidation circuits it is reasonable to conclude that the preg-robbed gold is either in a gold cyanide [Au(CN) - 2, AuCN] or metallic [Au°] form. However, in circuits with a pre-oxidation step possibilities increase and multiply even further because of water recycle streams containing apparent and not-so-apparent gold ligands. It is in these circuits where speciation of sorbed gold, i.e. the identification of the gold compound, is useful. The importance arises from the fact that proper identification of the sorbed gold species can be used to determine how, when, where and why gold was removed from solution, thereby identifying the exact cause of the problem and providing clues as to how it may be rectified.INTRODUCTIONTo the best of our knowledge, this is the first attempt ever to speciate gold preg-robbed by carbonaceous matter using a surface sensitive microbeam technique. This approach enables the direct determination of gold species sorbed on carbonaceous particulates, opening an entirely new field in the understanding of the chemistry of gold sorption on carbon. The reasoning behind this effort was to add to the current knowledge of the detrimental effect chloride ions have on gold recovery by the pressure oxidation and in particular why in the ensuing CIL step, gold is not being desorbed from the surface of the carbonaceous particles (Table 1)."

Jan 1, 2004

By S Vianna, K Caldwell, R Silva, T Olson, D Bell

Studies to enhance the FLSmidth forced air machine through changes in the design, showed important improvements through changes in the number of Rotor blades, stator designs, rotor air distribution and other designs features. The main outcomes from this study highlighted that increasing the number of rotor blades increased the selectivity while decreasing power requirements while stators with slots have better results in terms of recovery, flotation efficiency and selectivity than without slots.Also the rotor air distribution makes a difference in the design when comparing different distribution criteria whilst keeping all features of shape and number of blades etc constant. At the most efficient rotor air distribution design, copper recovery reached one of the highest values while keeping good selectivity. The possible explanation for that is the increase in the pump capacity indicated by the increase in the specific power.It was seen as significant that reduction in specific power for some designs tested compared with the then current standard design had an average of 30% less power consumption.As a result, FLSmidth was able to identify new designs that decreased power and improved recovery, as well as, identifying some designs that specifically improved fine and/or coarse particle recovery.CITATION:Silva, R, Caldwell, K, Bell, D, Olson, T and Vianna, S, 2013. FLSmidth flotation developments - Dorr Oliver machines, in Proceedings MetPlant 2013 , pp 413-430 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By E. M. Tignor

As a part of the program of promoting the conservation and efficient utilization of petroleum, studies are being made by engineers of the Bureau of Mines on secondary oil-recovery projects throughout the United States. In furthering that aim, engineering data concerning the reservoirs, methods of stimulating the production of oil, and other pertinent facts are collected, studied, and subsequently published so that others may profit by the experience gained. This report presents the results of a study made by engineers of the Franklin, Pa., office of the Bureau of Mines of secondary oil-recovery operations in the Boggs field, Spencer district, Roane County, W. Va., whore natural gas is injected into the reservoir to stimulate the production of oil from a so-called stripper field. The Boggs field, like most others in the Appalachian region, is one in which the major part of the natural energy that caused oil to flow through the reservoir to the producing wells during the primary stage of oil production has been dissipated. For all practical purposes, most of the oil produced in the Appalachian region at the present time can be considered to be from stripper fields. Consequently, secondary recovery methods are being used extensively in the oil-producing areas of New York, Pennsylvania, West Virginia, Ohio, and Kentucky for recovering some of the oil that was not produced by primary production methods.

Jan 1, 1949

By H. A. Watson

This circular, which is a revision and combination of two previous publications,3 4/ presents information on the different types of equipment that may be used to analyze mine atmospheres, with particular reference to the application and limitations of each type. Such information is frequently requested by mining companies, State mining departments, and other agencies concerned with safety in mining who wish advice regarding methods of analysis of mine atmospheres and the equipment necessary for establishing laboratories for that purpose. Since the Haldane-type apparatus is particularly applicable to the accurate determination of carbon dioxide, oxygen, and combustible gases such as methane in mine atmospheres, that apparatus and the method of operation are described in detail. The circular presents results of a critical study of the accuracy attainable with the Haldane-type apparatus in the determination of methane in concentrations of the order of 0.25 percent, by volume. Analytical procedures involved in the other methods discussed are presented in publications referenced in this circular. Information is given also on the various accessory equipment needed in a laboratory for the analysis of mine atmospheres, and suggestions on laboratory design are included. INTRODUCTION 'The analysis of mine atmospheres plays an important part in promoting safety and maintaining safe conditions in mining operations, particularly in coal mining, where the flammable gas methane presents a continuous hazard in Nome mines and may be encountered unexpectedly in others.5/ Methane has been encountered also, often unexpectedly and with disastrous results, in noncoal mines and in tunnels under

Jan 1, 1956

Flotation of Smithsonite by Using Siloxane Cationic Surfactants as Collectors

Sep 13, 2010

By Theophile S. Yameogo

Les ressources naturelles ont en général été le moteur du développement économique et social des nations. Les pays aujourd?hui développés sont pour la plupart d?anciens eldorado, charbonniers ou pétroliers. D?autres le sont toujours. L?Afrique fait cependant figure d?exception : même en étant comblé de ressources naturelles exceptionnelles, les pays de ce continent croulent sous le poids de la pauvreté et de ses acabits que sont les maladies, la famine, la guerre et l?insurrection sociale. On reconnaît néanmoins qu?il y a des cas particuliers comme le Botswana, la Namibie, l?Afrique du Sud. Face à cette situation, beaucoup de scénarii ont été proposés sans pour autant porté les fruits espérés. Le rapport Brundtland suggère que le développement durable est la clé du succès car elle veille à la prospérité économique, à l?équité dans la société et à la pérennité dans l?environnement. Pour l?Afrique, beaucoup de facteurs doivent être considérés et les solutions se doivent d?être pratiques et éthiques. Le futur ingénieur des mines qui a écrit ce rapport, apporte sa vision de la situation non sans avoir auparavant analysé les faits. Cette démarche, qui se veut avant tout éthique, inclut les aspects sociaux, économiques et politiques. Introduction In the 40s, 50s and the 60s, many economists, among which Harold Hotelling from South Carolina University, thought that developing countries could reach socio-economical success by extracting their natural resources such as oil and minerals. The current economical disaster seems to have contradicted that belief and critics like Davis Graham (Colorado School of Mines) and Michael Ross (University of California at Los Angeles) even suggested that extractive activities stop in Africa. But the experts of the World Bank (Mining Department) and some mining and oil companies are committed to reverse the tendency by implementing a new approach. Considering the principles of sustainable development defined in the Brundtland report (1987), we decided to analyze the possibility of giving the extractive industry a catalytic role in creating a socially, economically and environmentally development in Africa. In other words, can we continue to mine and extract oil in Africa for its blossoming future under the ruling of the sustainable development? In the following, we start by explaining the African socio-economic and political context. After a brief definition of the sustainable development, we explain why, for Africa, some believe in the extractive industry and some don?t. In the end, we draw out conciliatory arguments.

Apr 1, 2005

By W. Lee Daniels

Significant deposits (> 4,000 ha) of heavy mineral sands were discovered in the USA Coastal Plain of Virginia and North Carolina in 1989. The majority of these lands support highly productive row crop agriculture, and the development of restoration protocols that would return these lands to agricultural use was deemed to be critical to the long term sustainability of mining operations. Virginia Tech worked closely with all stakeholders to develop appropriate restoration protocols and to coordinate their implementation. Full-scale mining operations at the Old Hickory Project in Virginia were initiated in 1997 by Iluka Resources Inc., and restoration protocols have continued to evolve in response to a variety of economic, technical, and social issues. Approximately 750 ha of land are in various phases of backfilling and final reclamation. Return of these lands to agricultural row-crop production has been complicated by lateral variability in mine soil physical conditions, excessive compaction, and limited topsoil return. However, within the past two years, a series of tailings deposition and soil reconstruction practices have been developed and implemented that significantly improve post-mining soil productivity. Deep ripping and appropriate use of organic soil amendments have been particularly effective at restoring post-mining soil productivity.

Jan 1, 2005

By D. Bessinger, J. Nell

The electrical conductivity of rutile was optimised as a function of time, temperature and gas composition. These optimised conditions were used to treat rutile/zircon feed prep concentrate samples from a South African heavy minerals producer, prior to electrostatic separation. Enhanced separation between rutile and zircon was obtained when compared to untreated samples. Samples treated in a hydrogen atmosphere and cooled in nitrogen showed the best separation when passed through a high tension electrostatic separator using conditions of high sample temperature and high relative humidity.

Jan 1, 2005

By Jun Lu

There are many factors affecting the strength of pillar, including width-to-height (W/H) ratio, mechanical properties of coal and surrounding rocks, property of partings in the coal, and the interface property between coal seam and the roof/floor. In this paper, the effect of varying pillar?s width-to-height ratio (W/H=3, 5, 7, and 10) and coal/rock interface cohesion (Cj =50 psi, 150 psi, and 300 psi) on pillar strength has been studied. The confinement effect of W/H ratio and interface shear strength is investigated by studying their effects on the average minimum principal stress developed in the pillar. The deformation behavior of the coal pillar is investigated. It is found that the pillar?s transition from strain softening to strain hardening behavior depends on its W/H ratio and the interface shear strength.

Jan 1, 2008