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By Frank L. Hess

In 1876 cassiterite was identified in the placer gold from the northern Black Hills, and such a mixture could have come only from Nigger Hill or one of the streams draining the hill, because in no other part of the northern hills have cassiterite and gold been found together. Nigger Hill is in western Lawrence County, South Dakota, and on it is the little camp of Tinton. The Wyoming line runs along the west side of the hill and crosses the ridge which is the hill's continuation about miles north-northwest of Tinton.

Jan 1, 1938

By J. A. Capp

For certain classes of electric railways a steel conductor is preferable to the oldcr atld more commonly used overhead trolley-wire. The third-rail presents a rather better appearance, because of the absence of an overhead structure; it is easily installed, cheaply maintai~ied, presents s large area for conducting and collecting the current, and is therefore particularly suitable for high speed and heavy service. With costs calculated on the basis of equal coilductirity in rail aud trollej-wire, the third-rail constrrictiol~ is cl~caper than thc overhead trolley. But the average interurban road will lise a trolley-wire of considerably less conductivity than would be obtained with the smallest size steel rail (about 60 lb. per pard) that mould ordinarily be used, and here the first clost of trolley construction would generally be less thau that of the third-rail. While no third-rail installation has jet bee11 in operation long enough to give figurcs of value, it ~vould appear that the cost of maintenance of the thirdrail construction should be less than that of the overhead trolley. This consideration, together with that of sightliness and adaptability (particularly in the case of terminals, yards and very heavy or high-speed service), will frequently off'set the higher cost of the third-rail construction and make it the preferable means of' conducting the current from thc generator to the car-motor. For the first third-rail installations, old track rails were used when obtainable, and these old rails were supple~rlented with new rails of standard T-section and composition. With the coming of the very heavy, high-speed service during the past few years, the resistance of these old and new standard T-rails was found to be so high that they mould not carry the high currents necessary without too great a drop in the line-potential. The rails would, therefore, have to be suppleme~~ted with addi-

Jan 1, 1904

By Neillm Alastair S.

"This paper looks at what has happened in the past decade in the rare earth industry, particularly for those companies outside China trying to develop alternative projects to the Chinese dominated supply chain. The rare earth industry has gone through a metamorphosis over the past decade. The industry was basically unknown outside China until overnight it became the next hot topic on the financial streets of Canada and Australia. Suddenly various junior miners shifted from uranium and other out-of-favor commodities to rare earths as funds were easy to access from an investment community that did not understand the complexities of the space. The initial funding was done on traditional junior mining metrics of grade and deposit size. This has morphed over time to:1) Lights versus heavies2) Making a concentrate3) The importance of separation4) Off-take agreementsAt the peak of the market frenzy certain flagship operations were built using the “Not Made in China” moniker. Unfortunately certain errors were made during implementation, which are finally coming to the surface and making the rest of the pack wondering what will happen next. A review and update of some of the mistakes made and lessons learned will be discussed.BACKGROUNDAbout ten years ago awareness started to form around the rare earth industry and various groups recognized that because of the closure of Molycorp, Mountain Pass, and the dominance of China, there was a risk of uncertainty of reliable supply. This was not news for those active in the industry like Rhodia (now Solvay), the Japanese, South Koreans and other key consumers but to others it was like a light went on and rare earths became the new “.com” trend for investment banks, investors and some mining companies looking for the next hot topic.In the late 1990’s Molycorp accounted for around 20-25% of the world’s supply of rare earths, mostly lights (La, Ce, Pr and Nd), with small amounts of heavies from other sources. Then environmental issues forced the closure of the operation at Mountain Pass. Within six months China had increased production to plug the gap in supply. Around that time China was developing a strategy to leverage their position in rare earths and implemented a series of regulations to increase the value added component of rare earths inside China."

Jan 1, 2016

By H. Dale Nichols

[The growing importance of the Sundence (Jurassic) formation an a source of oil, in the Rocky Mountain area has prompted the making of a series of porosity determinations of core samples collected. from the reservoir sands of the Lance Creek oil field, Niobrara. County, Wyo. These analyses are preliminary to a stud of fluid and energy relations in the Basal Sundance reservoir of that field, and the determinations of porosity will be used in subsequent studies requiring, calculations of the volumetric capacity of the reservoir and estimation of the reserves of oil and gas. However, the porosity characteristics an of the Sundance sands in the Lance Creek field are factory that affect the solution of many current practical problems of development and operation. Primarily for that reason but also because it is recognized that porosity values of different oil-production sands are of widespread interest throughout the industry, the results of the initial work have been presented in tabular and graphic form with no attempt to evaluate their significance as they relate to the production history of the field.]

Jan 1, 1938

By R. Lowery

TODAY, man uses, at will, the land, the water, and the air to transport himself and his goods everywhere across the face of the world. He no longer thinks with wonder of the magic of conquering these elements - he takes his mastery of them for granted. He is, however, constantly striving to squeeze more and more efficiency from each mode of transport. Man's first method of transporting himself and his goods was, obviously, himself; then he acquired his first beast of burden - woman. Most other two-legged female animals carried their young around clinging to their fur. Human mothers were, generally speaking, furless and their offspring less 'Prehensile, and so slings and other trappings were invented to carry young children. Man's inventive genius soon adopted these devices for carrying other burdens, and for countless centuries woman carried all in order that man could walk unencumbered except by his weapons. Later other ?beasts of burden were trained and used, including dogs, horses, oxen, camels, etc. Man also discovered quite early that he could drag along the ground more than he could carry on his back.

Jan 1, 1956

By D. Limpitlaw

Industrial mining in Zambia started in the 1930s when the world class copper deposits near the border with Katanga were developed. The discovery of these deposits began at the turn of the century when the first claims in the Copperbelt were pegged at Chambishi, north of what became the town of Kitwe1. World War I and the difficulties of raising sufficient capital for such large scale undertakings delayed the exploitation of these deposits. Following this hesitant start, a large copper mining complex was built, resulting in the development of five major towns, all highly dependent on the mining and beneficiation of copper and cobalt. Copper became so important to the country that, on independence, the only non-mining town to make it onto a list of the top six was the capital, Lusaka. From commissioning of the mines to the end of the colonial period in 1964, copper production increased to just over 640 000 t annually2 (see Figure 1). After the establishment of the new Zambian state, production continued to increase, supported by a benign legislative environment and strong international copper prices. The government of Kenneth Kaunda was intent on improving the conditions of the rural poor and reducing unemployment in urban areas. To this end, the government embarked on an ambitious project of refocusing Zambia's economy away from the colonial role of commodity supply to one of decentralized mass employment. The Copperbelt industrial complex was key to the success of this approach, and in 1969 the Zambian State acquired a 51 per cent stake in Zambia's two main copper producing companies: Roan Selection Trust and Rhodesian Anglo American Corporation. The former became Roan Consolidated Mines Ltd (RCM) and the latter became Nchanga Consolidated Copper Mines Ltd (NCCM). In the year they were nationalized, the mines produced at least 720 000 t of copper? and employed approximately 48,000 workers (see Figure 2)2-4. The subsequent economic policies of the Zambian Government depended heavily on the state's ability to monopolize the proceeds of copper mining.

Jan 1, 2011

By Paul Worsey, Gillian Worsey

The explosives industry is about to reach a critical turning point in human resources. The average age of employees of the largest US explosives company is over 50 and an estimated 5,000 engineers are due to retire from the mining industry over the next decade, with less than 200 mining graduates per year nationally. Not just in the USA, this is a worldwide problem. In Canada the Mining Industry Human Resources Council (MIHRC), reported that older mining engineers are retiring early – at the age of 59.5 on average. It predicts that mining companies will need to hire 370 mining engineers by 2016 and 665 by 2021. The Minerals Council of Australia has predicted the need for an additional 86,000 mining professionals and skilled mine workers by 2020, and the Indian mining industry is also facing a shortage of between 2,500 to 3,000 engineers per year.

Jan 1, 2014

By W. J. Wiehagen

The Work Crew Performance Model (WCPM) seeks to define performance variability within similar tasks of an underground work crew and relate observed variability to a cost consequence. Performance variability is described using work site observations to determine the adherence to job elements con¬tained within a standard operating procedure. Key components of the WCPM include (1) job definition through task analyses and the ranking of job elements by perceived cost consequence, (2) observational techniques for establishing performance baselines by measuring adherence to safe and proficient job procedures, and (3) cost linkages between adherence to task procedures and measures of consequence for noncompliance. Data presented within this report were obtained through the study of shuttle car operation in an underground mine in Appalachia. Observed adherence to safe and proficient job procedures by opera¬tors matched well with the consensus profiles (measured through a nominal group technique) with min¬ing personnel. It was also found that experienced operators consistently outperformed less experienced, incidental operators. These findings imply potential use of the WCPM as a practical procedure for thinking systematically about the choices available to reduce performance variability. Field application of the model can offer useful data to evaluate training and financially support performance improvement strategies that can be tested for their ability to reduce human error.

Jan 1, 1994

By R. J. Fantel

The Bureau of Mines investigated the resources, costs, capacities, market relationships, and short- and long-run supply of phosphate rock and phosphoric acid. The 206 mines and deposits evaluated in 30 market economy countries contain an estimated 35.1 billion mt of recoverable phosphate rock (demonstrated resource level). U.S. resources are sufficient to satisfy the domestic and export markets for phosphate products well beyond the year 2000. Because of resource depletion at current producers, however, new properties (with higher cost levels) need to be developed if U.S. production levels are to be maintained. Existing worldwide capacity can satisfy expected demand through the early 1990's. Expansion at existing mines or low demand growth could mean that no new property development will be needed before the late 1990's. Worldwide, almost $8 billion could be required for development of new phosphate rock properties between now and the year 2000, given 3-pct annual growth in demand. Most properties that could develop in the 1990's would require price increases of 20 to 50 pct to break even. To earn a 15-pct rate of return on investment, prices must rise to nearly double the present level of $24 to $29 per metric ton.

Jan 1, 1988

By L. G. Austin

My first contact with industrial milling was during the time I worked in the electricity generating industry in the United Kingdom. In visits to power stations to investigate either deposits in the boiler furnaces or polluting deposits settling around the stacks. I had to check the performance of the vertical coal pulverizers, since poor pulverization aggravated both problems. Naturally, then, when I came to the USA in 1957 to take a PhD in fuel technology at Penn State, I was put to work to review the science of coal pulverization. After this reviewing, I was completely confused. On one hand, there was a well-developed understanding of stress-strain equations, and a rapidly developing knowledge of how stressed, brittle solids fractured, based on the Grifith crack theory. On the other hand, reading in the grinding literature gave me: -Kick's Law, which was clearly not correct in the light of modem fracture theory; -Rittinger's Law, which was also clearly not correct; -Bond's Third Law of Comminution, which was claimed to have something to do with the Grifith crack theory, but where the connection between the two was made by intuitive pseudo-scientific reasoning I could not accept; -the choice of mill motor power for the most common type of coal mill, the Raymond pulverizer, was calculated from the fan power required to move air through the mill. Although I could accept the empirical connection between the two, it made no sense from the point of view of fracture energy. Even today, most books or review chapters on size reduction start from these laws. Incorrect statements abound in the literature, such as "the Hardgrove Index is based on Rittinger's Law," which it is not, "The Bond theory states that work input is proportional to new crack tip length produced in particle breakage," which is not true, etc. My own test work showed that these "laws" did not fit the data for grinding of coal. At about this time, Epstein (1948) and Broadbent and Callcott (1956), following the original work by R.L. Brown (1941) at the British Coal Utilization Research Association, proposed describing breakage as a series of fracture stages. I took their concepts and developed the basic differential equation for a batch grinding process continuous in time, analogous to a batch chemical reactor. Robin Gardner then joined the project and did his PhD on treating batch grinding in the same way as a batch chemical reactor. He found that the basic equation had already been partially derived by Sedlatschek and Bass (1953) in Ger- many. We confirmed experimentally the validity of the equations for describing batch grinding (1962) and formulated the equation describing steady-state continuous grinding in a fully-mixed mill. At about the time this work was published, Gaudin and Meloy (1962) and Filippov (1961) independently published essentially the same equations, but without experimental proof of the validity of the concepts. I will give a brief overview of what these beginnings had led to in the design of mills for size and power, and show some of the results of this more detailed understanding of grinding processes. Concepts of Fracture Mills such as tumbling ball, rod, pebble and autogenous mills and vertical mills such as the Raymond, and E-type, apply compressive stress to lumps or particles relatively slowly. Compressive stress applied to a particle of an elastic brittle solid imparts overall strain energy to the solid and produces local regions of tensile stress, [(Fig. 1)] (Berenbaum and Brodie, 1959).

Jan 1, 1985

By Theodore Nagel

Fuel-oil, natural gas and coke oven gas, producing the higher temperatures of open-hearth current practice, have been gradually displacing producer gas the lowest cost fuel for open hearth operations. The lower temperatures of combustion products from producer gas is caused by nitrogen dilution. Practical Application of Combustion Thermochemistry One pound of carbon burned to CO produces 3,960 B.T.U. and one pound of carbon burned to C02 produces 14,140 B.T.U. The second unit of oxygen uniting-with gasified car-bon (-CO) produces (14,140 - 3,960) 10,180 B.T.U. which is;(10,180 - 3,960) 6,220 B.T.U. more heat than produced by the first, unit of oxygen forming CO by uniting with solid carbon. A review of the relative combustion heating values of commercial gaseous fuels reveals CO requires a minimum of air for combustion, and because of minimum nitrogen dilution and the high thermal release from CO higher temperature combustion products are produced from CO than from natural gas or from coke-oven gas under similar combustion conditions. Inert nitrogen diluent lowers the calorific value of fuel gas and its diluting effect is cumulative in lowering the temperature of the products of total, combustion. It is not only logical but, practical in partial combustion, converting bituminous coal to gas, to generate the gas, with reduced nitrogen dilution.

Jan 1, 1936

By Constantine C. Popoff

This report reviews and analyzes, by a simple analytical and logical reasoning, the conventional methods of reserve computations of mineral deposits described in various domestic and foreign publications. It brings together, formulates, and evaluates the principles underlying interpretation of exploration data; and ties such principles to the proposed classification of methods. The material is discussed in sufficient detail to allow general application.

Jan 1, 1966

By Juan Francisco Mori, Miguel Ángel Aucapoma, Pablo Zevallos

En este artículo se describe el prototipo de un equipamiento instrumentado digital cuya función es monitorear la condición de los techos de los socavones para evitar que se produzcan accidentes por desprendimientos generados por el debilitamiento de las estructuras que sostienen los techos, debido al corrimiento de las estructuras del macizo rocoso. Básicamente el sistema informa mediante la activación de alarmas pre-configuradas al interior de mina, con el propósito de prevenir y evacuar al personal.

Apr 30, 2020

By M. R. Geer

The widespread adoption during the past decade of the dense-medium process for cleaning coal increases the need for technologic studies of the process. Such studies provide information that will insure maximum usefulness of this process in its present form and may well lead to substantial improvements in design and opera¬tion. The Bureau of Mines has published the results of cleaning trials on a wide variety of coals in two dense-medium pilot plants5/ and reported the recovery of coal from waste by dense-medium treatment.6./ The present report deals with the viscosity of magnetite dense medium, an important subject about which virtually nothing has been published. Specifically, the report concerns methods for measuring viscosity, the influence of various medium contaminants on viscosity, the effect of viscosity on cleaning results, and the influence of viscosity on consumption of medium. Cleaning trials on four coals of varied density composition in a pilot plant, using mediums of different viscosities, showed a steady reduction in cleaning efficiency with increasing viscosity in every instance. However, the behavior of each coal in a viscous medium was distinctly individual. With one, an increase of only 1 centipoise in viscosity caused a reduction in recovery efficiency of 7.7 percent, whereas the same increase in viscosity with another reduced recovery efficiency only 2.7 percent.

Jan 1, 1957

Operator efficiency and control capability along with cost effectiveness have been the quest of mining, industrial, and mobile hydraulic engineers for years. The majority of the functions in present day fluid power systems are controlled by on/off control valves. They are inexpensive and provide easy installation and operation, but they lack the quality of fine control of load flow or what is sometimes known as "feathering the load". An alternate approach to obtaining this capability is the use of electro-hydraulic servo-valves, but their implementation into a system is complex, and they are expensive. As a result, electrohydraulic systems are still used primarily in the aerospace industry. Of late, a compromise seems to have evolved between the on/ off control systems and the servo-technology is the so-called proportional flow control valves. A proportional flow control valve meters fluid to the load in proportion to the input command from the operator. In principle, it is similar to a conventional flow control valve and is tailored to meet the control requirements from the load point of view. The hydraulic system using this valve usually works in an open-loop mode with the operator closing the loop. Incorporating load-sensing mechanisms and adoption of electrical/electronic signalling into the valve make it the "ideal valve" which designers have been looking for from a techno-economic point of view.

Jan 1, 1983

By Bernard Lewis

During the past 10 years the technical investigations conducted by the Explosives Division of the Mine and Explosives Bureau of the Bureau of Mines have been described in a series of summarizing reports prepared by Wilbur I. Huff, consulting explosives chemist of the Bureau. These reports covered the…

Dec 1, 1947

"Human accidents are caused by production accidents, generally ones (such as derailment of cars, falling rock, etc.) that have occurred numerous times before an employee was actually involved. Prevention of human accidents is, one of the essentials in cutting operation costs, and advocates of safety are studying economics to assist them in their work of preventing accidents.Workman's compensation insurance or compensation for human accidents is a true operating cost, and is the only purely tangible measure available which gives a measurement of the cost of accidents even though, as will be pointed out later, it represents but a portion of the total cost of human accidents.In using premiums paid for compensation insurance as a measure of the cost of accidents, it must be kept in mind that most insurance laws, as pointed out in a former paper (Serial 2590 of the Bureau of Mines) provide a waiting period before compensation for the lost-time wages starts, with the compensation limited to definite percentages of the wages. The waiting period and limited compensation combined tend to limit the amount paid to an injured workman who, if he receives 1/3 of the lost-time wage, will probably have been reimbursed as high as the average injured workman.The total or complete economic cost of human accidents, must include, in addition to compensation paid for lost time, and the portion of the lost-time wage suffered by the workman for which he is not compensated, the additional cost to the company through-(a) temporary decreased production by the breaking down of the morale, etc., (b) the breaking in of a new employee which is admittedly expensive,(c) the increased liability of human and production accidents caused to or by the new employee.Another charge against accidents, which is not included in the compensation payment, is the economic loss through the killing of as workman who has no dependents. Few of the States' laws require any compensation except burial expenses to be paid for fatalities to persons having no dependents. It is estimated by the United States Bureau of Labor Statistics that the economic loss through a fatality is 6000 shifts. If each fatality was compensated for this amount of time and at half-time wages, using an average wage of $5.00 per shift, the compensation for fatality based on the economic loss would be $15,000. but the average actual compensation paid for each fatality is about $3,000."

Jul 1, 1924

By Karsten Hagenah, Tor Jensen, Jens Laugesen, Øyvind Fjukmoen, Lucy Brooks

This paper discusses operational environmental threshold levels for exploitation of mineral resources in the deep sea. Such criteria are needed to be able to monitor and control deep sea mining with respect to the stringent environmental requirements that are needed. It is recommended to use existing environmental threshold levels for comparable underwater activities. Fields of application are mainly but not exclusively seabed mining operation activities under the governance of the International Seabed Authority (ISA). The threshold levels and limits mentioned in this paper are proposed recommendations based on other activities than seabed mining but are a proven and accepted approach in other maritime industry activities. An example of such other activities with proven and accepted environmental threshold levels are Oil & Gas exploitation activities in the sea. Background The first exploitation of mineral resources in international waters is coming closer. Presently regulations for exploitation for mineral resources in the Area are being developed by the International Seabed Authority (ISA). The ISA regulations will contain the framework related to environmental monitoring of exploitation. However, the regulations will not contain operational environmental threshold levels for the Contractor.

Jan 1, 2018

By Daniele Perondi

Diferentes resíduos são gerados pelas indústrias siderúrgicas, dentre eles o resíduo dos trituradores de sucatas (RTS). O RTS gerado pelas siderúrgicas brasileiras se difere dos demais países devido aos materiais que são alimentados no triturador. Assim, o objetivo deste trabalho foi avaliar as características do RTS gerado por uma siderúrgica brasileira. As seguintes técnicas foram utilizadas: identificação e quantificação dos principais constituintes, análise termogravimétrica, imediata, elementar, poder calorífico superior e teor de cloro e metais. Os principais polímeros presentes no RTS foram o poliestireno e o polietileno. A partir dos resultados de análise imediata, elementar e de poder calorífico superior do RTS, verificou-se uma elevada quantidade de matéria volátil (76,22% ± 6,90). Os altos teores de carbono (72,92%) e hidrogênio (9,86%), foram atribuídos à elevada quantidade de polímeros e borrachas presentes no resíduo. O teor de enxofre (0,21%) pode ser atribuído a presença de borracha no resíduo, enquanto o teor de cloro (1,33% ± 0,13) pode ser atribuído a presença do PVC no resíduo. O poder calorífico superior do RTS foi de 30,01 ± 1,22 MJ/kg, de forma que uma avaliação termoquímica mostra-se como uma técnica atrativa para a sua destinação final.

Oct 30, 2017

By Paul Madsen, Bade Sozer, Thomas Hennings, Eileen Test

The Rondout Bypass Tunnel in New York has two access shafts. The upper sections of the shafts are lined with steel pipe to resist a substantial net internal water head . Initial design included a ¾-inch-thick cement mortar lining (CML) for all three components. Because of concerns with CML application on large-diameter pipes, the protective lining was redesigned for shotcrete application. This paper discusses the details of that design, mock-ups, and shotcrete application.

Jun 13, 2023