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By Jesse J. Brown

Over 60 simple; were prepared and forwarded to Dr, S. Z. Toma, TPO, PMSRC as a result of this project. Included among these samples were various low temperature forms of silica. Samples of quartz, cristobalite, and tridymite with iron, manganese, and titanium impurities present were prepared. In addition, a long series of samples both wet ground and dry ground for times from 1/2 to 8 hours were prepared. Numerous miscellaneous samples were submitted which included kaolinite, calcite, muscovite, illite, montmorillonite, Ba3(P04)2, and YPO4 among others, in response to special requests from the TPO. The silica rich portion of selected binary (CA 203-Si02, In 203-Si02, Li20-Si02) Na20-Si02, PbO-Si02, SnO2-Si02, Sn02-Si02 BaGa204-SiO2 and SrGa204-Si02) and ternary systems (Na20-Ga203-Si02 and Li20-Ga203-Si02) was investigated to determine the effects of solid solubility on the stabilization of the high temperature forms of tridymite. In addition to the determination of the extent of these crystalline solubilities, observations were made. on the mechanism of the transformation of silicic acid to tridymite and the rate of the reaction in the presence of foreign ions,

Jan 1, 1973

By G. R. Moulder

A device was developed that measures dynamic stress (ultrasonic energy) transfer through installed rock bolts, a measure that is directly proportional to the degree of grout bonding of the bolt to the mine roof structure and thus the ability of the bolt to bear static stress. The rock bolt bond tester (RBBT) is a hand-held portable device that shows three ranges of bolt bond condition; i.e., one-third (Bad bond), two-thirds (marginal), or fully bonded. These are shown respectively by a red, yellow, or green light that displays for 4 s. RBBT performance was verified with 2 1/2-to 8-ft bolts installed in various types 0f mine roof structures (sands tone, shale, and boney coal-mud), and 15 now being tested by the Bureau of Mines in mines across the United States. The unit is about the size of a five-battery flashlight and contains the transducer electronics, and battery pack. The RBBT is designed for extreme ease of operation, requiring only manual contact with the bolt and signal read-out. The batteries are rechargeable and the package is designed for durability in a mine environment.

Jan 1, 1983

By H. L. Riley

Cleaning and handling of fine coal are generally conceded to be more difficult problems than preparation of the coarser sizes. Increased mechanization in the coal-mining industry has, in general, resulted in an increased percentage of the fine sizes in the total coal mined. If the coal fines are cleaned by wet methods, the minus-1/16-inch square-mesh particles cause most of the sludge and slurry problems encountered in preparing wet coal. Equipment that separates coal from refuse on the basis of specific gravity is not efficient on sizes that, because of their fineness, do not follow the same laws of hindered settling as the larger particles. Probably the best solution of fine-coal cleaning problems is to use other methods, such as flotation, that utilize other physical characteristics than those determining hindered-settling ratios. Regarding the type of flotation known as the Elmore vacuum-flotation process there has been a scarcity of data and information available in this country. An investigation has therefore been made to obtain additional date and information on this process under laboratory conditions. During this investigation an effort has been made to evaluate the relative efficiencies of vacuum and mechanical laboratory froth flotation cells. The investigation included float-and-sink, screen-sizing, and flotation tests on 2 different samples of 14-mesh to 0 raw coal and an a sample of slurry from the settling-tank overflow of a typical washer. One raw-coal sample was obtained from the American bed and represented a type of coal that is relatively easy to clean. The other raw-coal sample was from the Mary lee bed and represented a type considered difficult to clean.

Jan 1, 1954

By L. W. Berger, and R. I. Jaffee, D. N. Williams

The effects of hydrogen on the properties of binary Ti-A1 alloys containing 2.5, 5, and 7 pct aluminum and ternary alloys of the same compositions with added interstitial elements oxygen, nihrogen, and carbon were stzdied. Aluminum increases the apparent hydrogen solubility of the a-phase, resulting in a marked increase in resistance to impact embrittlement. In the Ti-5Al and Ti-7Al alloys, for example, the addition of 180 and 305 ppm hydrogen, respectively, did not cause embrittlement, while unalloyed titanium was embrittled by as little as 75 ppm. The role of aluminum in increasing hydrogen solubility of the a-phase probably accounts for the excellent hydrogen tolerance of a-ß alloys containing considerable amounts of aluminum. There is some evidence that aluminum retards the rate of hydride precipitation. If so, these alloys may be susceptible to slow-strain embrittlement. UNALLOYED a-titanium is extremely sensitive to small amounts of added hydrogen in that there is a marked decrease in notch properties. For example, as little as 100 ppm hydrogen is sufficient to lower the room-temperature notch-impact strength from over 100 to less than 20 in.-lb.' This loss of impact Strength has been associated with the Presence of hydride phase in the microstructure. Hydrogen in the amounts encountered in commercial practice

Jan 1, 1959

The Federal Coal Mine Health and Safety Act of 1969 limits to 2 milligrams per cubic meter (for dust containing a maximum of 5% quartz) the average respirable dust concentration to which individual miners may be exposed. Section 205 of the Act directs that an appropriate exposure formula for dusts with quartz content in excess of 5% be established. This formula, entered in F. R. Document 70-12351 filed September 16, 1970, is 10 milligrams per cubic meter divided by % quartz. Thus, the total respirable dust exposure permitted limits the quartz to a maximum of 100 micrograms. For example, if % quartz is 5%, 10 mg/5 = 2 milligrams, and (.05) (2 mg) = 100 micrograms. Similarly, if % quartz is 10%, 10/10 = 1, and (.10) (1 mg) = 100 micrograms, etc. If the % quartz is less than 5%, the 2 mg/M3 limit prevails.

Jan 1, 1974

By Travis Q. Lyday

During 1983, Ecuador's gross domestic product (GDP) decreased by a reported 3.3% in real terms, the second consecutive decline in the economy after more than a decade of growth generated mainly by petroleum export revenues. The slowdown was due, in part, to the effects of the world recession, lower foreign demand for oil, depressed world oil prices, and reduced demand and prices for Ecuador's traditional agricultural exports. Inflation accelerated to an estimated 55% annual rate. The sucre was devalued in March, for the second time in less than a 12-month period, by 27% after remaining unchanged during the previous decade. In addition, continuous adjustments were made every weekday, effectively devaluing the sucre another 30% by yearend. Ecuador's production of crude petroleum increased almost 12% in 1983 compared with that of 1982. Average daily production was 237,100 barrels per day (bbl/d), up from 211,300 bbl/d in 1982.

Jan 1, 1985

By Patrick P. A. Wolfs

In the summer of 2000, the ECR®/EFT® was first introduced in the Netherlands. After the first project a field test was performed together with other geophysical methods to prove the liability of these systems and their application in areas with soft soil and high groundwater levels. The objective of this test, which was carried out with three leakage detection systems, was to locate the holes. After this test several projects have been carried out. In this article the Dutch projects "Ringvaart Aqueduct" and "Bottleneck Limburg N296/N297" are mentioned.

Jan 1, 2006

By J. M. Boutwell

I. Introduction. THE object of this paper is to present a concise statement on the genesis of the copper- and lead-deposits of the Bingham Mining District, Utah. It is essentially a condensation of a chapter in a detailed report on this district, together with so much on geologic features, and on the character and occurrence of the ores as bears on the problems of ore-deposition. The studies upon which the paper is based were undertaken in 1900 under the direction of S. F. Emmons, Geologist-in-Charge of the Section of Metalliferous Deposits, U. S. Geological Survey; and a little additional data was secured in subsequent years. The evidence then obtained as to the genesis of the replacement copper-ores has led, to conclusions which differ somewhat from explanations hitherto current. Accordingly, it seems desirable briefly to present the facts together with the resulting conclusions in a separate paper.

Nov 1, 1905

By F. Dehghani, B. Rezaie, T. Ghosh, A. Sachan

Comminution is an integral part of the mineral extraction process. However, the influence of the comminution method (ball and rod mills) on silica and magnetite particle shapes has not been substantially investigated. Shape parameters for fractions of -250+212, -150+125, and -106+75 μm sizes were examined utilizing a scanning electron microscope and a Clemex vision PE image analysis system. The silica particles displayed higher elongation and flatness parameter values for rod mill products, but roundness and relative width parameter values of rod mill products are less than that of the ball mill products. Magnetite particle elongation and flatness parameter values of ball mill products in fraction sizes of -250+212 and -106+75 μm are larger than rod mill products, but roundness and relative width parameter values of ball mill products are smaller than rod-mill products, but for the -150+125 μm size range the result is converse. Furthermore, particle elongation and flatness increased with decreasing particle sizes of silica, whereas, roundness and relative width decreased for both Ball and Rod Mills. In case of magnetite, ball mill products displayed an increase of flatness and particle elongations with decreasing particle sizes but flatness increased and roundness and relative width decreased. Similarly for rod mills, magnetite fractions of -150+125 μm were found to have the largest values of elongation and flatness. INTRODUCTION Comminution alters the size and shape, causes lattice distortion, changes chemical composition, surface area, surface-free energy, and polymorphic transformation of all materials. The quantity and quality of such changes depend on specifications of the material feedstock, the type of mill being utilized, the specific energy input, ambient temperature, and environmental pressure [1]. The shape difference between the milled products depends on different grinding mechanisms and the respective breakage principles that these mechanisms depend on [2, 3]. With decreasing particle sizes, the nature of the particle surface become crucial [1]. The influence of the breakage technique has been found to be non-trivial and heavily dependent on the type of grinding mill used for particle size reduction [4]. Shape is an important industrial parameter for predicting particle behavior in downstream processes. The shape parameter affects the way particles burn, compact, are recovered, flow in fluids, sinter, float, agglomerate, fluidize, interact with pulmonary tissue, cut, abrade, react with chemicals, form structural materials, and retain and permit fluids to flow [5, 6]. The distribution of particle sizes and shapes are important for mining, civil and chemical, pharmaceutical, and various other industries with interest in the population modeling of atmospheric dusts, smoke, and grit [1, 3, 6]. The shape parameter not only affects the chemical, physical, surface properties of particles but is also important for downstream processes [5, 6]. Image analysis has been found to provide detailed information about size and shape of the particles and can be used for the control of product quality [4].

Jan 1, 2019

By Jimmy Thompson

The Santa Clara Valley Transportation Authority is designing the Silicon Valley Rapid Transit Project in San Jose, California. The project includes 6.9 km (4.3 miles) of twin-bored tunnels to be constructed through downtown San Jose using two earth pressure balance machines (EPBMs). This paper begins with a project description and update of the project status followed by a description of the relationship between anticipated ground conditions and EPBM requirements. Topics addressed include soil conditioning, abrasion resistance, annulus grouting, face pressure estimation, additional pressure control devices and control measures to limit over-excavation and settlement.

Jan 1, 2008

By William R. Vogel

The Bureau of Mines Information and Analysis organization collects worldwide data on virtually every commercially important nonfuel mineral commodity. These data form the base for tracking and assessing the health of the minerals sector of the U.S. economy. This data collection activity was instituted by the 47th Congress in an appropriations act of August 7, 1882 (22 Stat. 3291, to place the collection of mineral statistics on an annual basis. The most recent authority for the Bureau of Mines Information and Analysis activity is the National Materials and Minerals Policy, Research and Development Act of 1980 (Public Law 96-479, 96th Congress), which strengthens protection for proprietary data provided to the U.S. Department of the Interior by persons or firms engaged in any phase of mineral or mineral- material production or consumption.

Jan 1, 1989

By R. Du Plessis, J. D. Miller, D. G. Kotlyar

The low potential hydrophobic state of pyrite in amyl xanthate flotation with nitrogen is of particular interest with regard to the N2TEC flotation technology currently being used for the recovery of auriferous pyrite at Newmont’s Lone Tree Plant in Nevada. The N2TEC system had been found to operate satisfactorily, but cyanide in the flotation mill water appeared to be responsible for a loss in pyrite recovery. This supposition was confirmed with laboratory experiments and a program was initiated to study flotation chemistry variables by electrochemically controlled contact angle measurements. Experimental results show that activation of pyrite in such cyanide solutions can be achieved more effectively with lead than with copper. Subsequently, based on these fundamental studies, significant improvement at the Lone Tree Plant was achieved by lead activation, in which case the recovery increased to expected levels. The effect of activator is particularly significant not only with respect to pyrite depression by residual cyanide, but also with respect to collector (PAX) consumption and the initial state of the pyrite surface. Each of these issues is being studied in detail and research progress is discussed herein.

Jan 1, 2002

By F. D. Stevenson

Thermodynamic properties of metal halides and, in particular, vapor pressures have become of great importance in recent years owing to increased application of chemical processing to extraction of metals from their ores. Vapor pressure data serve not only as a valuable source of latent heat of vaporization and fusion values but also differences in metal-halide vapor pressures often provide the basis for their separation by conventional mass transfer operations. This literature search was made to provide a ready reference to experimental vapor-pressure data of metal halides and oxyhalides. Results are reported in two main sections: (1) A tabulation of vapor- pressure references for each of the metal halides (listed by metal) for which actual experimental data are reported (table 1), and (2) a bibliography of the citations. Metal halides and oxyhalides are listed by chemical formula and chemical name, based on the stock4 system. To facilitate location of the references, a listing of the journal titles and their abbreviations follows the bibliography.

Jan 1, 1963

By Paul S. Goodman

Volume I This report presents the first national survey of miners' attitudes and opinions about their-work. The goal is to present attitudinal data that bears on coal production. Interviews were conducted in 26 mines with 2,000 miners. High levels of cooperation were exhibited by management, union and the employees. Data are presented about miners' attitudes about general aspects of their work such as pay, supervision, their jobs, etc. Another section of this report reviews opinions about specific aspects of work performance. Recommendations are presented.

Jan 1, 1985

By B. W. Gandrud

This report presents the data of one of a series of investigations of the washability of Alabama coals as indicated by float-and-sink tests made by the Bureau of Mines at the Southern Experiment Station in cooperation with the University of Alabama and Alabama coal producers The Klondyke mine, operated by the Blocton Mining Co., is about 1 mile east of West Blocton, Bibb County, Ala., near the southwestern extremity of the Cahaba coal field. The Bureau of Mines already has published three reports that deal with the washability of Cahaba coals - one a washability study of the Clark bed at Marvel4/, one on the tabling of fine coal from the Thompson and Woodstock bed , and the third a washablility study of the Henry Ellen bed at Acmar6/.

Jan 1, 1939

By P Wood

Loy Yang Power (LYP) owns and operates a 2160 MW brown coal fired, base load power station in the Latrobe Valley, Victoria, Australia (Loy Yang A). It also owns and operates a brown coal mine that supplies fuel to its own power station and a nearby 1000 MW power station owned by International Power (LoyYang B). The mine supplies 32 Mt of coal per annum from an open pit, which is currently about 4 km long by 2 km wide and 180 m deep. LYP has 500 employees and a substantial amount of work is also carried out by contractors and consultants. GHD Pty Ltd(GHD) has been contracted to provide mine planning and earth sciences expertise. GHD is an international professional services company that operates globally in many market sectors including mining, industry and the environment. The company has major offices in Melbourne and also within the Latrobe Valley. This paper sets out the experiences that GHD and LYP have gained in establishing a unique alliance arrangement for GHD to provide a range of mine planning, earth science, dam surveillance and environmental services to LYP. The underlying philosophy of the alliance is to closely align the objectives of the two companies such that GHDÆs recompense for service delivery is proportional to the benefit achieved by LYPÆs business. Quality of service, whole of life costs and risk management are important aspects and are reflected in key performance indicators against which GHDÆs performance is measured. Currently GHD provide 20 000 hours of labour to LYP per annum, which are delivered by up to 120 staff who possess the required diversity of skills. The paper explains how the contract was initially let as a conventional service agreement and explains why the contract was transformed into an alliance. It then illustrates the operation of the alliance with reference to the 2006 work program. The paper concludes with thoughts on how the arrangement can be further developed for the future to the benefit of both parties.

Jan 1, 2006

By F. Schreiter

The Ore Mountains in Germany have a history of more than 850 years of underground mining activity. This has created a situation where thousands of old mine shafts and adits are due for rehabilitation. While no long-term stable rehabilitation was executed in previous centuries, those abandoned mine sites which date back to the uranium mining boom from 1945 to 1962 were rehabilitated immediately after mine closure according to state-of-the art technology. Over the years, however, it has become obvious that most of these sites are not long-term stable and thus it has become necessary to rehabilitate them a second time. Technical University Bergakademie Freiberg is carrying out a research project on the optimization of this process. 70 mine site rehabilitation projects, the technology and the materials used have been assessed. A technical guideline for future rehabilitation projects, based on the outcomes of this assessment, is under development with the goal to make it easier, faster and more economical to select and apply suitable designs and construction materials for dams, plugs and other rehabilitation structures in former uranium mines.

Feb 27, 2013

By S. Erçayhan, B. Derin, O. Yücel

In the present study, the production of low carbon ferrochromium (LC-FeCr) from chromite concentrates containing 55.09% Cr2O3 and 13.06% Fe via metallothermic process was investigated. For this aim, in the experiments, the aluminothermic reduction method was applied in an open crucible. 10% CrO3 + 10% NaClO3, 15% CrO3 + 5% NaClO3 and 20% CrO3 by weight of concentrate were added to the charge, respectively and the charge was reduced with aluminium. The experiments were done with the additions of 90, 100, 110, 120 and 130% of stoichiometric requirement of aluminium. The highest Cr content in alloys was found as 71.7% at 120% of stoichiometric Al whereas the highest Cr recovery in alloys was found as 71.8% at 130% of stoichiometric Al when the both charge contained 15% CrO3 + 5% NaClO3 by weight of chromite concentrate.

Jan 1, 2004

By J. R. Goode

"The Las Cristinas deposit in Venezuela contains reserves of 12.8 million ounces of gold at a grade of 1.20 g/t (Crystallex, 2004). The deposit comprises fully oxidized saprolite (SAPO) overlying a layer of sulphide-enriched saprolite (SAPS) which lies above carbonateleached bedrock (CLB) and carbonate stable or un-leached bedrock (CSB). Gold occurs at about the same concentration in all lithological groups. The bedrock units contain minor amounts of copper (about 0.1%) as chalcopyrite, while SAPO contains virtually no copper which has been leached and deposited in the SAPS zone.A previous owner began investigation of the Las Cristinas deposit in 1991. Over the next seven years, the company drilled 1,174 holes with a total length of 159 km, conducted extensive metallurgical testwork, including pilot plant operations, and completed feasibility studies. Construction was started in 1997 and again in 1999, however, on each occasion was suspended.Crystallex has been producing gold inVenezuela since the early 1990s. In 1997, Crystallex acquired Inversora Mael which had held two of the claims to the Las Cristinas concessions since 1986. In September 2002, Crystallex entered into a definitive agreement with the Corporación Venezolana de Guayana (CVG) to develop the Las Cristinas deposit.An extensive program of studies and testwork was started in late 2002 to determine an optimum development plan for Las Cristinas. Mine Development Associates, SNC–Lavalin Engineers and Constructors, SGS Lakefield Research Limited, J.R. Goode and Associates, and A. Laplante at McGill University acted as the main contractors.Because of the potential value of by-product copper, earlier flowsheets used carbon-inleach for SAPO, but processed all other ore types by flotation to produce a gold-copper concentrate with cyanide leaching of cleaner tailings to maximize gold recovery. Cyanide recovery was necessitated by the high copper content of the leach feed. Initial studies of available data by Crystallex revealed that direct leaching of all ore types would provide about 11% more gold recovery than the previously selected flotation route with reduced capital and operating costs.Bench and pilot-scale studies have confirmed that a SAG-ball mill-gravity-CIL route is very effective for all ore types and will give about 89% gold recovery. This paper describes the testwork conducted in 2003, discusses a 20,000 t/d plant design, and presents economic data."

Jan 1, 2005

Recovery of Pentlandite and Chalcopyrite from Tailings by Bi-Cyclone Powerful Flotation Column

Sep 13, 2010