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By A. M. Evans

"INTRODUCTION Exploration of the Iron Mountain and Bader iron-ore deposits in Llano County and the Gamble deposit in Mason County, Texas, was begun by the Bureau of Mines in January and completed in May 1944. The deposits had been examined by A. B. Needham, district engineer of the Bureau, in November 1942. Detailed geophysical studies by the gravity method as well as with a dip needle were made by the Bureau of Economic Geology 3/ of the University of Texas and the Federal Geological Survey. 4/ACKNOWLEDGMENTSIn the program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy., It is the policy of the Bureau to publish the facts developed by each exploration project as soon as practicable after its completion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests."

Apr 1, 1947

By Dilip Khatri

Helical pile anchors have gained acceptance over the past sixty years. Most recently they have been commonplace in the 20th century for the power utility industry in anchoring transmission towers, equipment platforms, street lighting, telephone poles, and radio tower applications. They have a strong proven industrial track record in these industries. As the cost of conventional deep pile foundations rises, the practical benefits of helical pile anchors becomes evident as a practical alternative. Noted for their uplift capacity, helical piles demonstrate equally strong compressive capacity as a structural foundation element. This paper summarizes the history, practical benefits, and technical requirements for helical piles. Significant structural testing has been completed at various universities. The practical benefits of these tests are discussed. One case example of proven performance is presented to demonstrate the advantages and disadvantages of helical pile anchors as suitable foundation elements.

Jan 1, 2003

By Harry E. Krumlauf

The year 1957 was one of declining metal price and production. Many lead-zinc-copper mines were forced to close, and the remaining mines limited production to stay more in line with demand. High cost of labor, supplies, and equipment and high taxes aggravated the situation. Some operators postponed or abandoned expansion programs because of uncertain economic conditions. Output was curtailed by elimination of over- time employment and reduction of the working force. The number of employes laid off was small- reduction in the labor force was accomplished by not replacing those who left a company's employ.

Jan 2, 1958

By E. P. Barret

Differences in the reducibility of iron oxide materials have been recognized for a long time. Limonites are deoxidized more readily than hematites, and unaltered magnetites are the most difficult to deoxidize. Sinters are found between hematites and magnetites and vary considerably in reducibility, depending on the sintering practice followed and on the degree of fusion of the product. The increased activity in the beneficiation of taconite recently has made available a new blast-furnace raw material, namely, iron oxide pellets made from magnetic taconite concentrate. Many of the data in this paper apply to these pellets, or glomerules, as they were called when this method of agglomerating iron ores was first considered. To clarify the terms applied to iron oxide materials in this paper, the following definitions are given. Agglomeration is the general term applied to all methods of compacting or consolidating fine iron oxide materials. Sinter is the product from a Dwight-Lloyd or Greenawalt sintering machine. Pellets are formed by balling fine, moist oxide in a rotating drum at room temperature, followed by heating in a shaft furnace to a temperature below that of incipient fusion to develop a permanent bond. Nodules are formed by heating the iron oxide material to incipient fusion in a rotary kiln. Briquets are formed in a mold under pressure, with or without the addition of a binder, and burned to develop a permanent bond.

Jan 1, 1949

Outotec?s direct leaching process is an atmospheric leaching process for sulphidic zinc concentrates. The direct leaching process, based on special leaching reactors developed by Outokumpu, is the most economical way to produce electrolytic zinc. The production scale applications of the process realized so far are in use at Boliden?s Kokkola and Odda zinc plants. A new full-scale application of Outotec?s direct leaching process will be started in 2008 in China. The process is integrated to the existing production plant, replacing part of the old production facilities by modern technology. Besides high zinc extraction the plant expansion and modernization offers also indium recovery, iron precipitation and solution purification processes. The process equipment includes tailor-made reactors designed on the basis of the work and experience of Outotec research center. Keywords: zinc, concentrate, atmospheric leaching, technology, indium, iron precipitation, solution purification, Outotec

Jan 1, 2008

By P. Trueman

A project is underway to convert a validated methodology to a system that will permit the near real time interpretation of loading data from longwall powered supports, allowing rapid adaptation of mining strategies, maintenance scheduling and set pressures for optimal roof control. Such a system has the potential to significantly reduce roof control problems and is a pre-requisite to successfully fully automating a longwall face. The development depended upon a robust methodology for interpreting the pressure sensor data coming from the face in the context of support strata interaction using a novel characteristic load cycle analysis concept. New software was developed capable of handling the large quantity of data emanating from a modern longwall with the current level of signal corruption and loss, accurately delineating load cycles and extracting the critical load cycle features essential for interpreting how the support and strata are interacting. Existing software being used to access the pressure data were found either to be incapable of delineating load cycles at all or, where they could, the accuracy was low, making it impractical to use them in combination with the new advances in load cycle analysis. The software is currently being extended from ?off line? to ?on line? in order to provide a real time response to changing strata conditions.

Jan 1, 2006

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

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

Jan 1, 2002

By George Otis Smith

WHAT American can enter this Western empire without his imagination being stirred by the stories of its past-yes, and even more by visions of its future! Whether we travel by rail or by auto, our pathway has its traditions of exploration and its records of early settlement. The mountain passes and the routes used by today&apos;s commerce are lasting memorials of the pathfinders whose unconquerable purpose was to search out a way-Lewis and Clark, Bonneville, Pike, Long, FrBmont, their names still live in your rivers and lakes and peaks. It was the glory of these adventurers that they spied out the land so that others might follow that long pro- cession of pioneers who occupied the new country- fur traders, gold miners, cattlemen, and homesteaders. Each of these pioneers attacked the problem of transportation in his own way, and each sought by his own method to win the resources whose richness had been reported by the pen of the Government explorer or by the swift rumor of the unnamed and unfamed adventurer. Trails were worn deep by these home or fortune seekers as they passed through the mountain barriers in successive waves-and these were waves that did not ebb, for this was an army of occupation. Along these main pathways of the West, as one historian has pointed out, the figure of chief interest was the sad- faced woman sitting on the front of the covered wagon.

Jan 1, 1926

By T. N. Singh

An evaluation was made on the cavability of the roof formation of Dishergarh seam including caving sequence, caving span, and load on powered support.

Jan 1, 1994

By K. Chief

American Indian lands contain a vast amount of renewable and non-renewable resources that have consequently been mined (Smith and Frehner). Therefore, it is understandable that tribes are concerned about environmental impacts from mining and their ability to minimize and mitigate these impacts. This has created a need to better understand mining and its environmental impacts. The University of Arizona Superfund Research Program Mining educational modules developed educational modules for tribal colleges focusing on environmental impacts of mining, remediation of mining wastes, and sociocultural impacts of mining. Educational modules are independently packaged units of study designed to enhance the learning process and can be modified and adapted to different learning scenarios and objectives. In addition to providing specialized knowledge, the modules feature hands-on activities, incorporation of technology, student involvement, discussion, and exchange of ideas. Modules will aim incorporate traditional ecological knowledge and approaches that promote effective science learning for native students. Modules are designed to augment existing associates of science programs (e.g. biology, chemistry) currently offered at tribal colleges and can be modified for use in K-12 education and for non-tribal audiences.

Feb 23, 2014

By W P. Darcey

Jabiru Metals completed a feasibility study on the Jaguar Base Metal Project in July 2005. The study was based on conventional truck haulage via a decline. Conveyor haulage was considered but not in sufficient detail to provide a meaningful comparison. The current study investigates the cost and productivity of alternative ore transport systems for the Jaguar project. The options considered are conventional underground truck, conveyor, road train, rigid frame truck, monorail haulage and shaft hoisting. Shaft hoisting was not considered in detail due to the high capital outlay for such a relatively short mine life of less than six years. This study goes beyond the common approach of evaluating haulage systems in isolation; it includes development costs, timing of ore production and costs associated with mine services as well as administration and milling costs. The results of this study indicate that the best haulage option for the Jaguar project is conventional truck using the Hitachi AH400 trucks. The net present value (NPV) for this option is A$8.13 million higher than the next best option namely the Kiruna E635 electric truck. The conveyor option has the lowest operating cost per tonne of ore but the longer development time negatively impacts on its NPV. The monorail option is considered impractical due to the number and length of trains required to achieve production targets.

Mar 21, 2011

By Desiree Willis

Disc cutters have determined excavation rates of rock tunneling projects for more than 50 years. First developed in 1956 by James S. Robbins, disc cutters (then 279 mm or 11 in. in diameter) were used to bore limestone of 190 MPa (27,500 psi) unconfined compressive strength (UCS) and were loaded with 7.12 t (15,700 lbs) each. Modern cutters have reached up to 508 mm (20 in.) in diameter and are typically loaded with up to 31.7 t (70,000 lb) to economically bore through the hardest of rock up to plus 400 MPa (60,000 psi) UCS. New developments, such as larger cutter diameters, are geared to increasing the bearing capacity and wear life of the cutting structure. This, in turn, increases cutter life, cutter load and cutter penetration. Disc cutters have also been re-designed on a small scale for use in hard-rock utility installations. Additional variables also affect the three factors, including cutter spacing on the cutterhead, cutterhead diameter and cutter materials.

Jan 1, 2007

By P. R. Khangaonkar

The industry of tin ore mining, beneficiation and smelting gives rise to a number of waste products like the beneficiation plant wastes (called amang), tin smelting slags, refinery dross etc. Some of the wastes deserve treatment to obtain economically useful products or to recover the metal values. The paper describes studies conducted on two materials, viz., struverite-middling (struverite-magnetic tin), which is an intermediate product of beneficiation circuits of tin tailings, and tin-smelting slags. The struverite middling was studied for treatment by chlorination using carbon tetrachloride, so as to yield vapour products separable by convenient condensation. The treatment was also found to lead to a tin-rich product amenable for treatment by known hydrometallurgical routes. The tin smelting slag was studied by alkali-leaching so as to avoid any dissolution of iron and it was possible to obtain an iron-free product solution suitable for high purity tin recovery.

Jan 1, 1996

By Mariana Gaudencio Barbosa Lima

O presente trabalho se baseia no estudo da recuperação de marcações adulteradas, em placas metálicas ferrosas, pela técnica de correntes parasitas (CP) /magnetografia (M) /visualização magneto-óptica (VMO) em comparação com o método destrutivo de restauração por ataque químico, utilizado pelos peritos criminais. Para tal, foram analisadas três amostras extraídas da sessão dianteira da estrutura do chassi de um veículo, as quais foram identificadas com caracteres impressos por indentações. Após a remoção das marcações por desgaste, as amostras foram analisadas pela inspeção CP/M/VMO e por ataque químico. Segundo os resultados obtidos, foi possível recuperar todas as identificações por ambos os métodos, além de compara-los segundo suas performances. Por conseguinte, a técnica não destrutiva demonstrou satisfatório desempenho na recuperação de marcações adulteradas.

Oct 30, 2017

By William H. Pomroy

This report describes Bureau of Mines research that led to the design, prototype fabrication, and successful proof-of-concept testing of an improved stench fire-warning system for underground noncoal mines. Stench systems are the most widely used means of warning driers in underground noncoal mines of fires or other emergencies. A stench system alerts miners that an emergency condition exists by injecting an odorant into the mine air. Although stench warning systems have been used successfully for over 60 yr, present systems suffer several serious shortcomings, including odorant toxicity, unreliability of warnings, widely varying stench concentrations, and others. In 1980, the Bureau began a research program to upgrade the stench warning system. The resultant system overcomes the deficiencies of existing systems by substituting tetrahydrothiophene for the commonly used ethyl mercaptan stench odorant, and through the use of a specially designed stench injector. The improved injector reliably meters stench fluid into either ventilation-air or compressed-air streams at a precisely controlled rate. Prototype hardware has been fabricated and proof-of-concept tested under bath laboratory and in-mine conditions.

Jan 1, 1985

By M. Pourkani, M. Karga, Samid Banis, Andre Laplante, G. Langari-Zadeh

"The Sarcheshmeh mine processes 40,000 t/d of ore grading 0.9% Cu and 0.035% Mo. Grinding is effected in single stage ball mills using 80 mm forged steel balls, with an average consumption of 850 g/t. One of its 5 m diameter, 8 m length ball mills was emptied to measure the ball size distribution. The broken balls were first separated from the total charge, and the remaining balls classified into five size intervals of +7O mm, -70 +60 mm, -60+50 mm, -50+40 mm, -40 mm.The charge was composed of 280,534 balls (excluding broken balls) with a total mass of 305,180 kg. It was found that 4.0 % of the balls were broken; the size distribution of the charge was also markedly different from the desired one, in particular for the small-sized balls. For instance, 9% of the balls were expected to measure 2.54 to 3.18 cm in diameter, but none was found. On the other hand, the amount of top size balls was 30% higher than expected. The radial hardness of balls, which was determined by cutting the balls in halves, showed that the hardness sharply drops when the balls become smaller than 65 mm. The unexpected ball size distribution was attributed to the rapid change in the balls radial hardness. Based on the measured ball size distribution, a new ball make-up charge which uses 80% of 80 mm and 20% of 60 mm balls instead of 100% of 80 mm was proposed and implemented. The effect of the new ball make-up procedure in terms of ball consumption and grinding efficiency is being investigated."

Jan 1, 1999

By J. D. Doherty

A. R. POWELL*—Mr. Doherty has outlined in a most thorough manner valid arguments for the development of an industry in this country making syn. thetic liquid fuels from coal. No thoughtful person will dispute the statement that it is essential to carry on fundamental and applied research and acquire engineering "know-how" by the erection and operation of two or three large plants in the near future. Considerations of national security indicate that this should be done, irrespective of any temporary present surplus of natural petroleum. It is the belief of the discusser and of many others interested in coal technology that our energy picture of the future will include an increasing utilization of coal directly, without any conversion to liquid fuel, as a source of energy. A fact that is sometimes forgotten is that petroleum fuels have often been cheaper than coal in many locations and over long periods of time, and this price factor has been of great importance in expanding the use of petroleum fuels at the expense of coal. Synthetic liquid fuel made from coal must necessarily be several times as costly as the coal from which it is made, and this fact alone will have a profound effect on the future energy pattern of our country. This complete change in the economic relationship between solid and liquid fuels will lead to the substitution of coal itself for many uses now supplied by the relatively cheap petroleum fuels. From the standpoint of conservation of our natural resources, the substitution of coal itself for liquid fuels wherever possible when the age of synthetic liquid fuel arrives is also logical. At least 50 pct of the energy of coal is lost during conversion to liquid fuel. Nor is this com-pensated for by a higher utilization effi-ciency of the liquid fuel in most cases. For example, modern steam-boiler plants can operate at equal fuel efficiencies with either coal or fuel oil.

Jan 1, 1950

By D. Auerswald, M. Kotze, V. Yahorava, T. Udayar

Uranium can be recovered from lower grade uranium ores (<800 mg/kg U3O8), leach residues, and waste dumps cost-effectively via resin-in-pulp (RIP). Using this technology, no solid/liquid separation or washing of the leach residues are required. Furthermore, the uranium recovery can be higher than with conventional methods. RIP technologies have, however, been perceived negatively due to concerns around potential resin fouling and losses. This paper highlights the advancements made in RIP and discusses a number of potential applications where the technology could deliver economic and consequential environmental benefits by reducing the uranium levels in the waste.

Jan 1, 2014

By H. Sis, D. Dahlin, S. Chander, C. Summers

Bench-scale selective-flocculation tests were conducted on samples of Florida and Western phosphate process tailings. Physical, mineralogical, and surface characteristics were determined for both types of samples. The flocculation tests investigated dispersant and flocculant types and doses, pH, and slurry percent solids, while other parameters were held constant. Where selectivity was achieved, phosphate minerals remained dispersed, whereas silicate minerals flocculated and settled. In single-stage tests, flocculants having low to medium anionic character effectively upgraded products at moderately elevated pH. Multiple-stage tests, and tests in which flocculants of lower molecular weight were used as site-blockers, gave improved results.

Jan 1, 2002

By Mateus Alves Segundo Paulino

No estudo de escórias de fornos elétricos a arco (FEA), o sistema CaO-SiO2-MgOFeO se destaca em importância quando os temas são a proteção aos refratários básicos e a produção de ‘escória espumante’. A importância da obtenção da escória espumante no FEA reside no fato reconhecido de que ela traz diversas vantagens para a produção de aço, tais como: economia considerável de energia elétrica, proteção de painéis, redução de ruído, redução no consumo de eletrodos, etc. Levando-se em conta que diversos fatores ligados à composição química são de grande importância na produção e estabilidade de bolhas de CO, neste trabalho diferentes diagramas de fase são produzidos como ferramentas para a previsão da composição das escórias mais favoráveis para a formação da espuma. São consideradas na investigação algumas características relevantes encontradas no FEA tais como: basicidade da escória, temperatura de 1.600°C e teores de FeO e MgO variáveis (que refletem os diversos níveis de oxidação do banho).

Jul 30, 2018