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By Klaus Rieker

Over the last 30 years Wayss & Freytag Ingenieurbau AG has gained a lot of experience in mechanized tunnelling on various major projects. During this period most important developments concerning the machine technology for EPB- and Slurry-Shields have taken place. Since the first application of a hydro shield for the Wilhelmsburg Collector project in Hamburg in the early seventies, several stages of development have led to the current state-of-the-art in mechanized tunnelling. The continuous improvement of TBM techniques allows the execution of high quality tunnelling, particularly with regard to maximum safety and efficiency. The practical experience of the construction companies is of essential importance in order to continue further development and improvement.

Jan 1, 2005

By J. B. Zadra

Tungsten, a comparatively new metal, is one of the important strategic war materials. In peacetime, tungsten is widely used as a filament in elec¬tric lamps and electronic tubes and is a vital constituent of some of the most important industrial alloys. High-speed tool steel containing tungsten and stellite alloys containing cobalt, chromium, and tungsten are extremely hard and resistant to corrosion. These alloys and the tungsten carbides are unequaled as cutting tools and in other wear-resistant applications. They play a prominent role in the present era of mass production. Alloys containing tungsten resist oxidation at high temperatures and have been key alloys in the development of modern aircraft. The adaptability of tungsten to new uses is expanding, particularly in the high-temperature range. Domestic production of tungsten has come from a large number of deposits in 17 of the 49 States; but, of the total domestic output from 1900 to 1956, more than 80 percent was produced from mines in North Carolina, California, Colorado, and Nevada. The average tenor of the mined ore was less than 1 percent tungsten trioxide (W03).

Jan 1, 1959

By Robert Keyes, Charle Knowles, Glenn Kendall, Gary Fletcher

"The metal mining industry in Canada has been dramatically affected by the changes that have occurred in the world mineral market place. World economic restructuring in the post ""oil shock"" period of the mid-1970s, greatly increased competition from suppliers in the developing countries, and commodity price and currency pressures have all combined to severely test Canadian competitiveness. In the new mining world, the rate of growth of demand for metals has declined due to product downsizing, materials substitution, and a relatively slower growth of over-all world economic activity.The interplay of market and political factors is complex. Canadian metal mining companies must compete in world markets against low-cost producers in developing nations whose priorities often appear to be centred on maximizing foreign exchange earnings to foster development goals and debt repayment. Many of these countries have high levels of government intervention in their mining industries. The result is a greatly in-creased number of suppliers all vying for a share of a world demand growing at a relatively slower rate than in the past. To be able to compete under these circumstances, Canadian companies have had to undertake 'survival mode' measures and look to new ways of doing things. In order to identify the effects that the recent market and economic trends have had on the Canadian metal mining industry, a study was undertaken by Canada Employment and Immigration to assess these changes and their implications for the metal mining workforce.The Canadian Occupational Projection System (COPS)—Sector Study Group with the cooperation of the Mining Association of Canada, undertook a human resource survey to gather current employment and occupation information. This formed an important part of the Canadian Occupational Projection System Metal Mining Sector Study. This article addresses the with survey results, a C.E.I.C. worker mobility study, and trends and issues that are changing the mix of jobs and the way they are being done.Figure 1 shows metal mining employment for the period from 1974 to 1984. It provides a clear picture of the employment swings that the industry has experienced especially during the recession period of 1981 to 1983. From 1981 to 1983, employment dropped by 14 000, from 68 000 to 54 764, and then dropped to its lowest point in 1984 of 52 783. We feel that employment in the medium term will be flat with growth in gold mines being largely offset by continued workforce rationalizing in other sectors.Perhaps the key point is that equivalent levels of output have been achieved in the recent period (1981-1984) with a workforce that is 25% smaller than it was in 1974. This also raises the questions which the COPS/MAC survey and COPS mobility study sought to clarify, namely, what jobs have been cut and where have these people gone? Equally important are the questions of occupational skill level changes, and what types of jobs are declining and which ones are becoming increasingly important, as economic and technological changes have altered the mining work place."

Jan 1, 1987

By Charles B. Carpenter

For many years, studies of ground movement and subsidence accompanying subsurface mining operations have been part of the research program of the Bureau of Mines. Periodic observations by engineers of the Mining Division of the Bureau of man-built structures beneath which mining operations are conducted offer indisputable evidence of subsidence in the form of creeks in masonry structures and fractures and depressions in tie surface of the earth. As the removal of subsurface rock and earth material by mining, especially by the room-and-pillar method, is equivalent to withdrawing some of the foundation of a building, subsidence of the formations above, the mining levels in certain air-as is easily understood as a gravitational adjustment of the overlying earth formations.

Jan 1, 1940

By V. Barranco, K. Yliniemi, A. Hubin, B. P. Wilson, D. Janas, M. Lundström, P. Hannula

Typical copper electrorefining electrolyte contains tens of grams of copper, some nickel and a wide variety of impurities. Some of these impurities comprise trace amounts of dissolved precious metals like Ag, Pd and Pt that currently are not fully exploited. This study presents an electrochemical method to recover precious metals via a combined electrodeposition-redox replacement (EDRR) process, where energy is used only to deposit copper during the ED-step, while the RR-step relies on the spontaneous replacement of copper by the precious metals (i.e. cementation). In order to conduct the recovery successfully, process parameters such as deposition potential (EDE), deposition time (tDE), redox replacement time (tRR) and the number of cycles (n) was adjusted. Investigations performed in synthetic electrolyte (40 g/L Cu, Ag = 10 ppm) proved the possibility to recover a high purity silver. Short deposition times (tDE) were found to result in small Cu particles that provided a suitably high surface area for silver cementation. In addition, experiments performed in real industrial electrolytes containing 44 g/L Cu and 54 ppb Ag (Boliden Harjavalta, Pori), demonstrated that EDRR could attain Ag recoveries of between 46–67% in an energy efficient, additive-free manner. INTRODUCTION The raw materials used in the state-of-art primary and secondary copper smelters contain mainly base metals, but also notable amounts of Ag, Pt and other precious metals. These valuable metals distribute mostly into the copper matte during the pyrometallurgical treatment (Tirronen et al., 2017) and end up into the cast anodes. During the electrorefining stage, metals more noble than copper such as gold and platinum, are not dissolved but enrich into the anode slimes. In contrast, silver may dissolve slightly and thus, minor chloride addition is used to retain silver in the slime as sparingly soluble AgCl. Moreover, other metals less noble than copper may also dissolve, such as nickel. Therefore the electrolytes used in electrorefining typically contain substantial amounts of copper, nickel and even arsenic as well as minor metals such as antimony and bismuth. In the Boliden electrorefinery these were reported to be in the magnitude of 51.2– 60.4 g/L of Cu, 10.9–15.8 g/L Ni, 7.2–15.9 As, 0.2–0.4 Sb and 0.1–0.4 Bi with an associated sulfuric acid concentration of 139–155 g/L (Lehtiniemi et al., 2018). Copper is the most noble of the dominating base metals in the electrolyte and is thus deposited on the cathode as 99.99% purity LME-A grade. Anode slimes are collected and subjected to precious metals treatment e.g. via pressure leaching—selenium recovery— Doré smelting—Ag refining—Au/Pt/Pd leaching and reduction process (Ludvigsson & Larsson, 2003). The Pori refinery, operating in Finland since 1941, not only produces 133 000 t Cu cathode and 2300 t nickel sulphate annually but also 66 t silver, 4.6 t gold and palladium and platinum (in year 2017).

Jan 1, 2019

By R S. Hamilton, S R. Grobler, M E. Greenway

The progressive development of underground mines frequently requires increased ventilation flow rates through mine shafts that were originally designed for lower rates. Where these shafts are equipped with conveyances running on rope guides, the higher air flow rates adversely affect the lateral motion of conveyances and could cause conveyances to collide with the shaft walls or with one another. Hence the safety impact of higher flow rates requires proper assessment. This can be undertaken by use of computer simulation models to predict the dynamic motion of the conveyances during hoisting. It can also be undertaken entirely by field testing, or using a combination of simulation and field testing. This paper discusses these techniques and makes cautionary remarks about setting an absolute generic maximum flow velocity for all shafts. Approaches to assess existing shafts for increased ventilation flow rates are also discussed.CITATION:Greenway, M E, Grobler, S R and Hamilton, R S, 2017. Safety impact of increased shaft ventilation on rope guided conveyances, in Proceedings Australian Mine Vent Conference 2017, pp 261–270 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By Charles B. Carpenter

For many years, studies of ground movement and subsidence accompanying subsurface mining operations have been part of the research program of the Bureau of Mines. Periodic observations by engineers of the Mining Division of the Bureau of man-built structures beneath which mining operations are conducted offer indisputable evidence of subsidence in the form of creeks in masonry structures and fractures and depressions in the surface of the earth. As the removal of subsurface rock and earth material by mining, especially by the room-and-pillar method, is equivalent to withdrawing some of the foundation of a building, subsidence of the formations above, the mining levels in certain areas is easily understood as a gravitational adjustment of the overlying earth formations.

Jan 1, 1940

By D. F. Strong, P. P. O'Neill

"The Isle aux Morts Prospect is the first polymetallic, sulphide mineralization reported from the Port aux Basques Complex of southwest Newfoundland. Zn-Pb-Cu-Ba-Ag mineralization hosted by quartz-muscovite semipelite, occurs at the contact between a quartz of eldspathic unit and pelitic unit with intercalated amphibolite are minerals comprise sphalerite-galenachalcopyrite, in order of decreasing abundance. The principal gangue minerals are quartz, muscovite, feldspar and barite. Three morphologic types of mineralization are present: massive with more than 50% sulphide, flanked on one or both sides by disseminated and/or banded types. The massive type of mineralization exhibits a :durchbewegung"" fabric of rounded silicate fragments in a sulphide matrix, characteristic of intensely deformed and metamorphosed sulphide bodies. Sulphide minerals have been mobilized and recrystallized and share the same metamorphic and deformational history as the host rocks. Quartz muscovite schist which hosts disseminated mineralization, displays a K2O enrichment and Na2O depletion, that is typical of alteration associated with sulphide bodies in volcano sedimentary sequences. Isotopic ratios of sulphur are comparable to those of volcanogenic massive sulphide deposits.Despite penetrative deformation and metamorphic recrystallization, features of the local geology and the mineralization suggest that the Isle aux Morts Prospect is volcanogenic in origin. IntroductionFollowing the release of a government lake sediment survey (Butler and Davenport, 1980), which indicated anomalous concentrations of metals in southwest Newfoundland, geologists with Utah Mines Ltd. discovered the Isle aux Morts Prospect, a Zn-Pb-Cu-Ba-Ag showing, located approximately 15 km northeast of Port aux Basques (Figs. I and 2). The mineralization occurs in quartz-muscovite schist and is the first significant basemetal discovery in the Port aux Basques Complex."

Jan 1, 1988

By Stephen P. Signer

To improve the understanding of the support interaction mechanics between grouted bolts and coal mine roofs and to help lay the foundations for improved design and evaluation techniques, the 0.8. Bureau of Mines has conducted laboratory, field, and analytical studies of the load transfer mechanics of grouted roof bolts. Mechanisms by which load is transferred from a bolt through the grout to the rock mass are analyzed. Strain gauges were installed on over 70 bolts and tested to observe the rate of load transfer when a force was applied at the bolt head. Laboratory and field tests were conducted to determine bolt-grout- rock interaction behavior in both the elastic and postyield phases. Long-term laboratory tests were run to determine the time-dependent properties of both polyester resin- and-gypsum-grouted bolts. Numerical studies using finite- element techniques were compared to the experimental results. Elastic tests showed that 90 pct of the applied load was transferred within 24 in of bolt length. Long-term tests indicated that creep is more significant in gypsum-grouted bolts than in resin- grouted bolts. Plastic studies showed that yielding of steel will translate down the length of the bolt from 6 to 20 in.

Jan 1, 1988

By Luís Carlos da Silva

Atualmente, uma das principais preocupações da humanidade está relacionada à questões ambientais, que motivam pesquisas para o desenvolvimento de materiais com recursos renováveis e amigáveis com o meio ambiente. No entanto, este estudo pretende comparar, à resistência dos compósitos reforçados com fibras naturais, portanto, favoráveis ao meio ambiente e compósitos reforçados com fibras de vidro, que por sua vez têm impactos ambientais desde a fabricação até à disposição. Treze compósitos foram confeccionados para essa pesquisa, contendo 0% de fibra, 30% de fibras de curauá e 30% de fibras de vidro em matriz epóxi e testados em uma máquina de tração. Os resultados mostraram valores mais altos para as amostras reforçadas com fibras de vidro, no entanto, para relacionar a tensão do compósito com à sua densidade de fibra, verificou-se que os compósitos reforçados com fibras naturais apresentaram resultados melhores do que os produzidos com fibras de vidro. Concluindo, pelo ponto de vista da propriedade mecânica, as fibras de vidro podem ser substituídas pelas fibras de curauá.

Oct 30, 2017

By L. M. Lowe, D. G. Feasby, J. R. Goode

"Rare earth resources usually contain minor amounts of radioactive elements. The most widely recognised sources of radioactivity are associated with thorium and uranium. However, also present in the resources are isotopes of rare earth elements (REE) that are themselves radioactive, including lanthanum (La-138), lutetium (Lu-176) and samarium (Sm-147). These radioisotopes, as well as remnants of the natural thorium (Th-232) and uranium (U-238, U-235) decay series, can contribute to significant levels of radioactivity in mixed REE concentrates and in separated products. Levels such as these can present challenges for transport, transboundary movement, product storage, workers’ health and safety, as well as waste management issues at the facilities that separate out the individual REE’s. These are discussed in this paper. A particularly challenging radioactive isotope is Ac-227 (a decay product in the U-235 decay series). Actinium behaves chemically similar to lanthanides and hence normally concentrates with REE multi-element composites. Reliable analysis of Ac-227 is not widely available and the methodology required to deal with this challenge is briefly described. A principle reason for minimization of radioactive content throughout REE processing is restrictive specifications by concentrate purchasers in order to reduce waste management challenges. Approaches to the minimization of radioisotope content in REE concentrates and separated products are outlined in this paper."

Jan 1, 2014

On Monday, June 27, 1921, at 6 p. m., twenty-four members of the Institute from. Colorado and New Mexico, left Denver on the Union Pacific for Rock Springs, Wyoming, arriving there at 9:42 a. m., June 28th. The party was met at the depot by the Rock Springs committee and a large number of the local Institute members. The day was spent in visiting the Central Power Plant of, the Union Pacific Coal Company and adjacent mine, the new 'E Plane, the Reliance, Dines, Winton and Sweetwater coal properties in the district. At noon a very elaborate lunch was served in the First Aid Building at the Reliance mine, which was most heartily enjoyed by all. In the evening the members and friends visited the new Rialto theater and saw the pictorial exposition of the' "Sky Pilot". The evening terminated with a dance in the ballroom of the Masonic Temple from 9:30 until midnight, concluding one of the most enjoyable days which the Institute has ever spent in Rock Springs. At 12:3o a. m. the original party, augmented by six members from Rock Springs, were again enroute to Salt Lake City, arriving there at 8:30 in the morning of Wednesday, June 29th. The Hotel Utah had been selected by the local, committee as the headquarters for the convention, and the majority of the -members at once proceeded to that place where the books were opened and the paying of dues and registration of the members were carried on until 11:45 a.m. At noon a majority of the members were entertained at the L. D. S. Tabernacle with an organ recital, which was up to its usual standard of excellence.

Jan 1, 1921

By P. Mbele

Iron ore concentrate is not easily transported to, or processed in, ironmaking plants, therefore it is necessary to agglomerate. This paper will determine the possibility of agglomerating Sishen concentrate into suitable ironmaking feedstock. Pelletizing is one of the conventional and preferred agglomeration processes for iron ore concentrate investigated at Kumba Value-In-Use Laboratories. Sishen concentrate was mixed with binder, and then pelletized using a laboratory pelletizing disc; afterwards the green pellets were indurated at high temperatures to give strength high enough to survive handling and lessen disintegration in the shaft during ironmaking. Sishen pellets have satisfactory physical and metallurgical properties which make them suitable feedstock for the direct reduction processes. These were tested under Midrex shaft operational conditions and performed well, with a metallization of 94.47% being attained.

Jan 1, 2012

Prier to the date of this contract, Ocean Energy had developed and demonstrated a high efficiency fluorescent caplamp which operated from a standard 4 volt miner's caplamp battery. This unit produced about five times the light output of the standard incandescent miner's caplamp. The Company believed that the major market for this unique caplamp was in the industrial and municipal applications. Because of the additional safety requirements for coal mining use, and in conjunction with the much smaller market in the mining industry, the additional expense and difficulty of modifying this caplamp to comply with the Federal and State coal mine regulations were not considered at that time. Recognizing the potential of this lamp for improving illumination conditions for underground coal mining, the US Bureau of Mines contracted with Ocean Energy to make the required modifications to this lamp to bring it into compliance with the Federal and State of Pennsylvania regulations, and thereby, make this lamp available to the anthracite and bituminous coal mining industry. At the outset of the contract, the injection molds for the caplamp housing were being completed, and only prototype, hand fabricated, units were available for tests. The Bureau evaluated these prototype units and formulated a performance specification for the miner's version. Light level and distribution, weight, size, angle of tilt, and operating duration were all specified. In addition, it was required that the caplamp be com¬patible with existin charging equipment at the mines and that the final design be in full compliance with MESA Schedule 6D and he ultimately approved by MESA, Approval and Testing, as well as by the Pennsylvania Bureau of Deep Mine Safety. The scope of this contract covered the modifications required to achieve these objectives. It was agreed by the Bureau that all rights to the lamp, including design, material combinations, circuitry, etc. would remain with Ocean Energy. The charger/adapter system and components, which were developed under contract funds, are disclosed hero and become public knowledge and property. Patent applications have been filed by Ocean Energy to protect the mechanical and electrical design aspects of the lamp. It should be noted that this report contains details, designs and data which may be covered by one or more Ocean Energy patent applications, and disclosure herein is made only to provide better understanding of the contract results.

Jan 1, 1975

By D. Su

This paper presents the details and results of a preliminary investigation into the response of borehole pressure cells (BPCs) in soft coal. Two parallel approaches, laboratory calibration and nonlinear finite element simulation, were adopted for deter- mining the BPC K-factor, which was defined as the ratio of cell pressure change to the corresponding change in external pressure. Results from both the laboratory calibration and the nonlinear finite element simulation revealed a nonlinear response of cell internal fluid pressure to external loading. The K-fact& also is shown to increase with increasing setting pressure and decreasing medium modulus. -Depending on the setting pressure, the K-factor for coal having a Young's modulus of 1.6 x lo5 psi ranges from nearly 1.2 at 2,000 psi of external pressure to 1.485 at 8,400 psi of external pressure. The improved under- standing of BPC behavior leads to the more accurate calculation of BPC K-factor in coal which significantly improves the correlation between pillar pressures measured in underground coal mines and those predicted by nonlinear finite element simulations of these pillars.

Jan 1, 1990

This field guide is designed for use in planning pollution control and reclamation activities on small sand and gravel operations. Its purpose is to assist operators in selecting environmentally desirable pollution control and reclamation procedures based upon their particular mining situation. The guide includes information on interpreting physical and cultural factors that must be considered in planning and implementing a mining and reclamation program, achieving environmental protection objectives, and improving community/industry cooperation. Included as appendices are a summary of state laws and a list of additional readings on the subject.

Jan 1, 1981

By C. F. Weinaug, R. W. Farley, J. F. Wolfe

A rapid, accurate method for predicting the dew points of gas condensate systems and their subsequent normal and retrograde phase behavior with pressure decline has been developed. The method predicts dewpoint pressure, volume percent liquid, condensate content of produced gas, and the liquid and gas compositions at pressures below the dewpoint pressure. Use of a modified form of the BWR equation of state, which was established by regression calculations on experimental data from several gas condensates, provides depletion behavior predictions that are significantly improved over predictions using K-values based on convergence pressures and Standing's correlation for density. INTRODUCTION Prediction of complex hydrocarbon-mixture thermodynamics is fundamental to reservoir and gas process engineering. In particular, accurate descriptions of phase behavior are needed to plan production operations for gas-condensate reservoirs. Although analysis of reservoir behavior during producing and cycling operations can be made for simple reservoir models, extensions of these studies to more complex reservoir systems are still difficult, both with regard to numerical techniques and the phase behavior of the fluids. This report presents a mathematical method for handling the complex phase relationships encountered in retrograde condensates; it represents an advance in reservoir behavior technology in that it will aid the development of closed-form mathematical representations of total production systems. A typical phase diagram for a complex hydrocarbon mixture is shown in Fig. 1. When the reservoir temperature T, is higher than the critical temperature Tc, and lower than the critical-condensation temperature Tct' the mixture is a gas condensate. Decreasing the pressure on a condensate while maintaining nearly constant temperature will result in two phases forming at the dew point. Further decrease in pressure will cause additional liquids to be formed. This phenomenon is called retrograde condensation. As pressure continues to decrease, normal phase behavior regions are encountered (liquid vaporizes as the pressure decreases) until the low-pressure dew point is encountered. When a gas-condensate reservoir is produced, gas is withdrawn and the volume of fluids in the reservoir remains nearly constant as the pressure declines. Heavier components tend to accumulate in the liquid phase as a result of retrograde condensation, while lighter components tend to concentrate in the vapor phase. Thus, as the gas is produced the composition of the gas and the condensate

Jan 1, 1970

By D. Kwietnewski

The 4th bore of the Caldecott Tunnel is a 50-ft horseshoe shaped highway tunnel located in the hills east of Oakland, California. Tunnel excavation was mostly completed using one of the world?s largest commercially available roadheaders, a Wirth T3.20. The geologic profile included seven different geologic units, which displayed a range of different behavior with regard to excavation and initial support. Following a brief introduction to the excavation and support methods, this paper will discuss roadheader performance in the various geologic units encountered during excavation. Comments will also be made concerning the relationship between the roadheader method of excavation and observed ground convergence during excavation.

Feb 27, 2013

By G. J. Hearn

between particles in the classifying region is then

Apr 1, 1995

By Mehmet Guney

Acceptable working environments in production areas and service openings of Mindola Mine on the Zambian Copperbelt are currently maintained with an air volume of 1000 cu m/s and 5500 kW of installed refrigeration plant. It is planned to open up additional deeper areas of the mine for future production. Temperature problems, due to the increased heat generation from various underground sources are recognized as potential hinderances to efficient production. Findings of research work indicate that the present total heat output of 58,000 kW will inevitably increase by the second five-year period of the deepening program to 52,900 kW and by the fifth five-year period to 63,200 k\V. Estimated WB and DB temperatures, representing the total heat generation in stope faces and development headings during these same periods are predicted to increase to 53.8/40.2 °C and 35.5/42.1 °C respectively. It is assessed that the nominal refrigeration capacity needs to be progressively increased to 9,000 k\V This paper deals with the thermal problems in Mindola Mine, current heat output calculations, future prediction of temperature and heat load in various working areas of the mine with the application of computer programs and interpretation of data in order to find the effective solution for long-term planning of ventilation and air-conditioning.

Jan 1, 1982