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By Steven W. Hunt

Appropriate seals, portal ground improvement, and compatible shaft construction techniques are vital elements for launching and receiving tunnels effectively in urban areas where adjacent property requires protection from excess ground movements. This paper focuses on seals and ground improvement along with shaft wall types, required to launch or receive tunnel boring machines within wet, permeable ground at the portal zone. The paper also discusses probing to verify suitability before the tunnel eye is cut. Methods addressed include: rubber gasket seals; soft eyes; double walls; top hats for reception; and, portal zone ground improvement (permeation grouting, jet grouting, un-reinforced slurry diaphragm wall panels, ground freezing, deep soil mixing, dewatering, and over-excavation and backfilling). This paper focuses on challenges with launch and reception of pressurized-face TBMs with precast concrete segment linings. Challenges related to pipe jacking are discussed in a separate paper titled ?Mitigating Microtunnel Launch and Reception Challenges? (Hunt and Finney 2008).

Jan 1, 2008

By J. R. Thoenen

In the summer of 1937 the authors began a series of time studies of the various processes employed in the production of crushed stone. These studies, made at quarries scattered over the eastern and southeastern parts of the United States, have not been completed, but to make results available to thee industry as early as possible it was decided to publish summaries of the studies made to January 1, 1939, as a series of progress reports. The first of these reports dealt with power-shovel loading and was issued as Report of Investigations 3461 in September 1939. The present circular discusses analyses of the time Studies of the haulage systems at the same quarries. OBJECT OF STUDY The pressure of business problems frequently requires the entire attention of quarry management and in consequence internal plant economies often are neglected, Also, operating officials absorbed in their local problems are prone to overlook possible economies that would attract attention immediately were they critically examining another plant. The authors felt that similar studies of many plants by impartial engineers -would disclose possibilities for cost reduction or greater efficiency in internal plant processes.

Jan 1, 1939

By Ren G. Dong, Jay Kim, Daniel E. Welcome, Won Joon Song, Charles Hayden

Prolonged, extensive exposure to hand-transmitted vibration could cause a series of vibration-induced disorders in the vascular, sensorineural, and musculoskeletal structures of the human hand-arm system, which have been collectively called hand-arm vibration syndrome (HAVS).1 To assess the risk of HAVS the international standard ISO 5349-1 (2001)1 recommends using the root-mean-square (rms) acceleration of the measured vibration with a frequency weighting. While a few epidemiological studies have reported results consistent with the predictions made according to the recommendation, many other studies have reported results with large discrepancies.2 This may be partially attributed to the time-averaging effect involved in calculation of the frequency components, especially for impact type tools. Because the spectral characteristics of impact tools change dramatically with time, a time-frequency (T-F) analysis can provide better characterizations of such highly transient vibrations. The analytic wavelet transform (AWT) is an ideal T-F analysis tool because it possesses the advantages of both the Fourier transform and the wavelet transform.3 The objective of this study was to explore the application of the AWT method for characterizing the impact tool vibrations and assessing their exposure risk. Methods Five tools (two chipping hammers, two riveting hammers, and one concrete cutting saw) were used in this study. The saw vibration was measured when it was used to cut a section of road pavement during a repair. The vibrations on the other tools were measured by the procedure specified in ISO 8662-2 (1992).4 A sampling rate of 16,386 Hz was used in the measurement. The AWT and Fourier analysis were applied to these signals and to identify their characteristics. Results Figure 1 compares the T-F characteristics of the accelerations measured from the relatively steady concrete saw and a riveting hammer. The frequency weighting specified in ISO 5349-11 was applied in the calculations. The comparison clearly shows that the two tools have completely different T-F characteristics.

Jan 6, 2006

By S. Pinard, J. MacLellan, G. Ehlert

"The Kidd Creek concentrator is looking actively for alternative technology as means of reducing operating costs in their concentrate handling section. The use of pressure and vacuum filters to eliminate the multiple hearth dryers would have the most beneficial effect. The dryers which constitute the greater portion of concentrate drying costs consume about 35,000 m3 per day of natural gas.After the evaluation of various filters by Kidd's technology group, it was clear that, because of the low final moisture requirements of 5.5 to 6% H20, few filters were able to achieve this target economically. Lately attention has focused on the Andritz hyperbaric filter. Testwork has shown that target moistures can be achieved with an appreciable reduction in operating cost.1.0 INTRODUCTIONThe Kidd Creek Concentrator is located 28 kilometers east of Timmins, Ontario. The ore is hauled by the Kidd Creek Railroad to the concentrator where it is milled to produce separate copper and zinc concentrates.Projected concentrator feed for 1991 is 3,750,000 tonnes of ore grading 3.3 % Cu and 4.7 % Zn. The concentrate production is expected to be 458,080 dry tonnes of copper concentrate at a grade of 25.7 % Cu and 265,020 dry tonnes of zinc concentrate at a grade of 54 % Zn.Currently, there is active investigation toward cost reduction through implementation of new technologies. One area which has been extensively evaluated is the concentrate dewatering and drying section. In that section, the multiple hearth concentrate dryers represent the largest source of operating costs, mainly through maintenance and energy costs (electricity and natural gas). The replacement of these dryers with filtration technology that could produce the required concentrate dryness would represent substantial savings.In September of 1990 filtration testwork carried out by Andritz Ruthner showed that Kidd Creek copper and zinc concentrates could be filtered to below 6 and 8 % moisture respectively. In late May 1991 the laboratory testwork was duplicated on siteand one month later a 5 m2 pilot filter was tested on site. Based on the pilot test results, an economic evaluation was performed. It indicated that a reasonable payback could be realized if hyperbaric filters were to replace the existing concentrate drying section."

Jan 1, 1992

By J. D. Lowell, L. Quevedo

I will talk today about a porphyry copper exploration program now underway in the Amazon jungle in the southeastern part of Ecuador near the border with Peru. The project is unusual for two reasons: first the deposits are of Jurassic age, 153 m.y.o., which is unusually old for porphyry copper deposits and they may be the most significant pre-Tertiary age porphyry deposits known. Second, the district was found only six years ago which makes this the most recent discovery of a totally new porphyry copper district. The new porphyry district, known as the Zamora River Copper Belt, or the Corriente Copper Belt, is a north trending area 50 km long by 10-15 km wide, which is nearly aligned with the axis of the Jurassic age Zamora batholith and with the course of the Zamora river. Gencor in 1994 initiated a regional grassroots gold exploration program based on reconnaissance geologic mapping and geochem sampling which did not find a gold mine, but which identified the San Carlos porphyry copper system in April, 1995. In a later reorganization between Gencore and Billiton the Ecuador project was transferred to Billiton and between the Gencore work and Billiton’s a total of 10 porphyry copper systems were found over the next four years. In the period of 1997 - 1999 Billiton drilled a total of 11,000 meters of wide spaced core holes in the San Carlos, Panantza and Kutukus prospects. In October 1999 Billiton concluded a farm-out, joint venture agreement with Corriente Resources and Lowell Mineral Exploration for additional exploration of the Zamora property. This is funded by Corriente and managed by Lowell Mineral Exploration and a total of 28,000 m of core drilling was completed through August 2001. An immediate result of the Corriente Lowell project was the discovery of potentially commercial ore reserves in two new deposits at Mirador and Warintza. Additional closer spaced drilling was done in the Panantza deposit and additional drilling is planned at San Carlos, in targets related to Warintza, and elsewhere.

Jan 1, 2002

By N. L. Wimmler

"INTRODUCTION The Southern Cross district in Deer Lodge County, Mont., has been chiefly a gold producer. Most of the production has come from gold-bearing hematite-limonite ores. Some of these ores were mined and shipped to smelters for use as flux in smelting copper ores. A magnetite deposit in the Pomeroy property, containing no gold or other economic nonferrous minerals, was mined from 1921 to 1923, the ore being shipped to smelters for flux.The iron-bearing deposits in the Southern Cross area were examined by Bureau of Nines engineers/ on June 28, 1943, and October 14, 1943. As a result, a Bureau exploration project was recommended; it was conducted during 1944. A magnetometer survey was first made of the magnetite-bearing area at and in the vicinity of the Pomeroy property. Exploration by diamond core drilling was then conducted within this area, and in the Southern Cross and Hold Fast properties. The cyanide tailings dump at the Hold Fast mill was sampled by auger drilling.This report presents the data obtained by the Bureau of Mines exploration."

Dec 1, 1946

By Wilhelm Knickmeyer, Johannes Henneke

PREFACE For about 1 year Bergbau-Forschung GmbH, central research institute of the German Coal Mining Industry, undertakes full size tests for waterjet assisted tunnel¬boring in German coal mines (Fig. 1). These tests are performed with a tunnelborer of 2.6 m diam in an upper [ ]

Jan 1, 1979

By Vahid Tajdar

The behavior similarity between pile and cone penetration test, has guided the researchers to use the CPT results in prediction of piles bearing capacity. In this article, artificial neural networks have been used to study about relation between cone tip and sleeve friction strength obtained from cone penetration test and ultimate pile bearing capacity, obtained from static pile load test. Artificial neural networks "ANNS" is a form of artificial intelligence. ANN tries to dramatize the human nerves & brain system biology structure in self-structure. In this article, the results of relevant studies about the prediction of ultimate pile bearing capacity in especial area of soils are presented by use of back - propagation neural networks. The results of static pile load test up to failure on 63 piles with closed end and CPT test results in the place of construction these piles use in order to confirm and creation ANN model. Comparing predicted ultimate pile bearing capacity by utilizing ANN with the numbers which are predicted by 5 common traditional methods shows that using of artificial neural networks is a suitable method for predicted ultimate pile bearing capacity in identified area of texture of soil moreover it has a better operation in comparison with common traditional methods.

Jan 1, 2006

Experimental petrology may be used to accurately constrain PTX conditions in order to calibrate and understand geologic processes. This method may be used to answer postulated questions, by recreating known geologic conditions and observing changes in the experimental charges. The purpose of this project was to determine the eutectic composition and temperature in the ternary system PbS-FeS-ZnS ¦ (Ag2S), at ambient and elevated pressures and elucidate if the sulfides of the Broken Hill orebody may have been partially molten during highgrade (granulite facies) metamorphism. The study determined the eutectic temperature and composition in the system PbS-FeS-ZnS to be 800¦2¦C and 62.5% PbS, 30.5%FeS, 7% ZnS respectively, at one atmosphere, and the eutectic temperature at 27 kbars was found to be 960¦C¦10¦C, with a eutectic composition enriched in ZnS relative to the one atmosphere eutectic. the addition of lwt.% Ag2S to the system depresses the eutectic temperature to 772¦2¦C at 1 atmosphere and below 810¦5¦C at 5 kbars. The conditions of peak metamotphism for the cental and southern areas of the Broken Hill Block, New South Wales, Australia , lie above the solidus of the PbS-FeS-ZnS-Ag2S system, strongly suggesting that partial melting occurred in the orebody.

Jan 1, 1998

By Dave Ragland

The SDSU tunnel and underground station are the first of these type facilities to be constructed by the Metropolitan Transit Development Board. Because there is no previous experience, and because tunneling activities are associated with some risk, he MTDB has undertaken a very proactive and wide reaching program to identify and control risks during construction. Finally, because the tunneling activity and underground station is on the San Diego State University, MTDB is working closely with their staff to identify construction impacts and mitigation’s, and thus ensure a quality project for both agencies.

Jan 1, 2001

By M. Wright, A. H. Mwale

Opportunities to promote enhanced eco-efficiency (i.e. the simultaneous improvement in economic and environmental performance) for the minerals industry exist across the whole value chain. However, given the current operational models of major companies within the industry, and their focus on refining of primary ore bodies, it is important to understand where such opportunities might lie within minerals beneficiation, as it is here that major environmental pressures are felt. This paper examines the combination of unit technologies in a minerals beneficiation train, and explores the inter-relationship between energy input and water consumption for a given mineralogy and product recovery, as these are two critical environmental issues which affect the overall viability of many minerals plants. In particular, we review constitutive relationships for each of the sub-processes of comminution, flotation, and tailings dewatering, and suggest how these might be integrated into a unified hybrid model, with particle size distribution as the key design variable. Such a model can then be used to explore the trade-offs between different performance objectives (be these technical, economic or environmental) as part of a multiple-objectives optimisation exercise. In this way, it may become practical to envision situations in which concentrate grade and recovery are sacrificed, marginally, in order to reduce energy demand in comminution, and improve overall water recovery. In addition, this work provides a useful baseline against which to analyse the potential for dry processing. This becomes more relevant as the industry commits to advancing the sustainable development agenda in the face of the increasing life -cycle costs and impacts of minerals processing operations, coupled to declining ore body grades, and the desire to maximise recovery of minor and trace elements. Some specific observations for copper are offered, supported by operational data from Zambian copper mines.

Jan 1, 2003

By Frank Parrish

History and performance data of 17 water-injection projects in Cooke and Grayson Counties in north Texas are presented for the purpose of studying and comparing operating practices and oil-recovery techniques. Water is injected into Strawn and Canyon sands of Pennsylvanian age. The principal formation flooded is the Strawn, which ranges in depth from 725 to 6,900 ft in the projects covered. Estimated ultimate recoveries range as follows: Primary, 22 to 494 bbl per acre ft; and secondary; 63 to 296 bbl per acre ft. These figures represent the following percentages of original oil in place: Primary, 10 to 46 pct; and secondary, 8 to 23 pct. Shallower projects; 725 to 1,500 ft in depth, had higher average primary and secondary recoveries than did deeper projects. Crude-oil gravity, which ranges from 20° to 45° API, was not relatable to yield of secondary recovery oil. Analysis of the data indicates that five-spot injection patterns will yield the highest percentage of oil remaining at start of flooding; that is, 28.8 pct for five-spot injection patterns, compared with 20.8 pct for line-drive patterns and 11.6 pct for random patterns. Waterflooding in this area appears to be very successful. Secondary recoveries of most projects are expected to nearly equal primary recoveries.

Jan 1, 1963

By E. P. Carman

1. CARMAN, EVERETT P., OPPERMAN, MARTHA, NISHIYANA, SALLY, AND RACOOSIN, LEE. Bibliography of Bureau of Mines Investigations of Coal and Its Products, 1945 to 1950. B. 528, 1954, 60 pp. 40 cents. 2. ROSE, HAROLD J. Industry-Sponsored Coal Research in the United States. Chap. in Proceedings: Fifth International Conference of Directors of Mine Safety Research. B. 489, 1950, pp. 9-12. $1.25. Minerals Yearbook 3. STRINER, HERBERT E., CARMAN, E. P., AND GOODING, RICHARD M. Review of the Mineral-Fuel Industries in 1952. Minerals Yearbook 1952, Fuels, vol. 2 (pub. 1954), pp. 1-28.

Jan 1, 1958

By Pierre L. Labelle

Non electric Dual Delay initiators have revolutionized many aspects of underground mining. The units are used in all types of underground blasting operations. Some operations, due to the complexity and variety of their blasts, have extremely large inventories of conventional non electric products. The Dual Delay system has drastically reduced these inventories and has added an important element of versatility to blast designs.

Jan 1, 1994

By Manqiu Xu, Peter Wells, Gord Bacon

"A methodology is proposed for milling flowsheet design using flotation rate, selectivity and residence time distribution data. The flotation rate data and the difference in flotation rates between the main minerals to be separated are determined from laboratory batch tests. The residence time distribution (RTD) data is calculated using the tanks-in-series model assuming each flotation cell is a perfect reactor. The rate, selectivity and RTD data can be used to calculate the optimum flotation cell number in a bank for rougher/scavenger in a commercial plant.This methodology is demonstrated in a case study of a nickel sulfide ore. It is shown that miniplant rougher/scavenger data can be closely predicted from a batch test using the proposed methodology.INTRODUCTIONIt has been the trend in the past several decades that large flotation cells are increasingly used. This is largely driven by the economics as ore grades are getting lower and the rate of ore processing must be increased in order to keep mining operations economically viable. The development and evaluation of 250 to 500 m3 WEMCO SmartCell and Outokumpu TankCell flotation machines are well in progress. There are many advantages in using large cells: fewer cells, less floor space, lower power cost (although this is now being questioned for fine particle flotation), simpler circuit, simpler control, and lower auxiliary equipment cost (Arbiter, 1999). As flotation cells are getting larger, the importance of cell hydrodynamics, namely, air/slurry dispersion, power intensity, froth transfer, residence time distribution (RTD) and short-circuiting are being fully recognized (Jonaitis, 1999; Weber, et al., 1999; Gomez and Finch, 2002). It is not the intention of this paper to discuss flotation cell scale-up. The intention is to answer what is the optimum number and size of cells in a flotation bank for a given throughput. Figure 1 illustrates this problem facing design engineers. The same mean residence time required for a given throughput can be achieved in a single large cell, or many smaller cells in a row. A few cells of large size may be more cost-effective but they may not be as effective as more cells of smaller size in achieving the optimum metallurgy."

Jan 1, 2005

By K. Fleck

Energy West Mining Company (EWMC) has implemented a geologic program for improving stability and support requirements along deep two-entry longwall gateroads at its Deer Creek Mine operations located near Huntington, Utah. Together with geotechnical monitoring and concurrent review of mine seismicity in cooperation with MTI staff, it has become possible to improve longwall layout designs for two seam extraction of the Hiawatha and Blind Canyon seams. The geologic program consists of surface and in-mine exploration drilling, surface and in-mine geologic mapping, rock mechanics testing and detailed measurements of changes in depositional and structural conditions during development of every longwall gateroad. The geotechnical program consists of underground measurements at seven locations in two neighboring mining districts located in the Hiawatha and Blind Canyon coal seams under moderate to deep cover. Within the last five years, additional measurements, including data on seismicity and face conditions, have been incorporated into the data collection program for verifying the insitu coal strength and load transfer mechanisms for improving two-seam designs and support systems. Geologic mapping results are also used to predict local stability of headgate and tailgate entries, combining mine roof mapping, stratigraphic profiles of the coal and roof, and depth-of-cover information and dual-seam mine overlays, for use by operations personnel in planning roof and rib support for the retreating longwall sections.

Jan 1, 2012

By H. L. Burmeister

This is one of a series of publications by the Bureau of Mines dealing with mining methods and costs at representative operations in the United States. The report describes all phases of the mining methods for the open-pit operation and milling practices employed at the Vermont Asbestos Mines in Lamoille and Orleans counties, Vermont. A brief history of discovery and development of these asbestos deposits is given, and the ore deposits are described. Methods employed in exploration, sampling, and estimation of tonnage and grade are outlined. A breakdown of available cost figures is summarized in the last section. All asbestos ore produced in this area has been won by the use of surface-mining methods. Two quarries, the Lowell and the "C" Area, are in operation. The quarries combined are producing and the mill is processing approximately 3,500 tons of ore per 3-shift day The average 40,000 tons of crysotile asbestos fiber produced at this plant annually accounted for 96 to 98 percent of the total fiber produced in the United States in 1958. The mine is located (fig. 1) approximately 4 miles north of Eden Mills village on the southeastern flank of Belvidere Mountain (fig. 2).

Jan 1, 1962

By Eugene Stephenson

CRITICAL analyses of the work expended in producing oil by the utilization of gas energy have appeared in the publications of Shaw,1 Pierce and Lewis,2 and Herold,3 authors who have ably discussed the factors which must be taken into consideration in comparing energy consumed per barrel in various wells which are flowed by means of gas-lift. However, two distinct phases of oil production are concerned with the ratio of gas energy consumed to oil produced. One of these phases is the gas-lift, which utilizes the differential gas pressures for the purpose of flowing oil, whether these pressures be natural reservoir pressures or be induced by artificial compression of gas or air. The other phase has to do with prorating oil production in pools which are operated either as units, or are subject to such restrictions as those imposed at Oklahoma City by the Corporation Commission, or, by similar controlling groups in other fields. An abundance of literature is available relative to the problems of flowing wells by gas-lift, but the first suggestion that the energy of the gas within the oil and gas pool might serve as a basis for proration, appeared in the timely article by McWilliams.4 Much of the. dissatisfaction with proration in certain fields is because some operators feel that besides the hazard to the wells which accompanies the test, the method of allocating production on the basis of the "potential" gage is inequitable and gives some operators a distinct advantage over others.5 The most severe penalty may be exacted from the most progressive operators or those who attempt to produce their oil with a minimum quantity of reservoir gas. If :no difficulties ever

Jan 1, 1931

By David Allen Jones

A depleted county gravel pit was rehabilitated by contracting an artist to convert it into sculpture, rather than using traditional reclamation methods. The sculptor's ideas were generally implemented as designed, but problems arose because of a faulty survey and severe weather. Public reaction was critical. A design symposium was presented by retaining six artists to prepare designs for varied sites. A public forum was offered and video-documented for broadcast. A new art-reclamation project grew out of this project.

Jan 1, 1981

By Ronald T. Mayerle

A mineral survey of portions of two contiguous WSAs (Wilderness Study Areas) along the South Fork Owyhee River in southwestern Idaho and north-central Nevada was done by the U.S. Bureau of dines in 1984. The portions of the WSAs, known as study areas, have a combined area of 47,610 acres. The Idaho study area consists of 42,430 acres of the 42,510-acre South Fork Owyhee River WSA (ID-16-53). The Nevada study area consists of 5,180 acres of the 7,840-acre South Fork Owyhee River WSA (NV-010-103A). The Idaho study area is within the Boise District of the Bureau of Land Management, and the Nevada study area is within the Elko District. In the Nevada study area, no claims or hard rock mineral occurrences are known.

Jan 1, 1986