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By Mohammad R. Jafari

The Camp Dresser & McKee (CDM)/Hatch Mott MacDonald (HMM) joint venture has been engaged by the New York City Economic Development Corporation (NYCEDC) to provide engineering ser-vices in connection with the replacement of two existing siphons which cross New York Harbor between Staten Island and Brooklyn. The project involves the construction of a 72-inch diameter pipeline within a 12-foot diameter tunnel beneath the New York Harbor. The tunnel will be constructed using either slurry or an earth pressure balanced (EPB) tunnel boring machine (TBM). This paper presents the results of an extensive geotechnical field and laboratory testing program including advanced frozen soil tests (uniaxial compressive strength tests, triaxial tests, and uniaxial creep tests), in-situ vane shear and pressure meter testing, and a marine geophysical survey (seismic reflection technique) to ascertain the complex subsurface conditions along the tunnel alignment and shaft locations. The paper will also discuss the design and construction aspects and the challenges associated with each component of this project.

Jan 1, 2008

By B. S. Fee, R. R. Klimpel

"Froth flotation is the most widely used and economic means of concentrating metal sulfide ores such as those containing copper, lead, zinc, nickel, molybdenum, and pyrite. Also recoverable are other metal species that are often associated with sulfide ores such as cobalt, platinum, gold, silver, etc. Most of the initial developments made with the process of froth flotation in the early 20th century were based on the processing of metal sulfide ores. It is the relative technical and economic ease of floating metal sulfide minerals with small amounts of appropriate frothers and sulfur containing (thio) collectors that has been a major economic driving force behind the rapid expansion in the supply of metals such as copper, lead, zinc, and nickel that has occurred in the world's economy in the last 50 years. This author estimates that 1.6 billion tons of sulfide ores are processed each year (1980) in the free world based on the froth flotation process.While there has been a tendency for the quality of metal sulfide ores in any one geographic location to deteriorate over time due to mining intensity, the overall global supply of sulfide minerals is still very large. Thus, the physical supply side of sulfide ore concentrates has not been under strong technology improvement pressure with increasing metal demands. Part of this is due to the ability of capital to consistently move to new geographic locations having suitable grade sulfide ores. In these moves, the actual froth flotation technology used (including collector chemicals) has had to change little. As an illustration of this trend, of the approximately 80,000 metric tons of thio collectors used commercially (1980) in the free world, almost 98% were known and manufactured in some form 25 years ago (1). This is clearly not typical of reagent development in other process related industries. In addition, the industrial scale practice of froth flotation applied to sulfide ores has proceeded since the 1920 s with often little direct (predictive) scientific explanation due to the extreme complexity of the flotation process. Empirical testing has been a mainstay of industrial flotation reagent development and use. Even today there is often strong disagreement between researchers as to the mechanisms of chemical flotation practices that have been performed successfully at an industrial scale for many years."

Jan 1, 1987

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 Stacy Loizeaux

The Beirut Hilton Hotel, which was built in 1975, but never occupied, was imploded on Sunday, July 14, 2002 by Controlled Demolition, Inc. (CDI) of Phoenix, Maryland and their client, Optimal Engineering Consulting & Contracting, SARL, (OECC) of Antelias, Lebanon to make room for a new hotel. Twenty-seven years ago, just days before the grand opening, the Hilton Hotel became the site of fighting in Lebanon’s Civil War. Christian and Muslim militiamen fought room to room for control of the building and other nearby hotels. The Hilton, two other major hotels and other high-rise buildings were ravaged by the fighting. The building was one of the three major hotels badly damaged, but not rebuilt, in Lebanon. Located in the City Center, the Hilton stood out in a major redevelopment area which, in recent years, had erased the scars of the 15 year long Civil Wa r.

Jan 1, 2003

By Rudolf E. Greuer

This report contains the practical application of a computer program for the simulation of ventilation systems under the influence of mine fires and other emergencies on five hardrock mines. The introduction describes the need for such a program, its basic features, and the range of its applicability which is mainly a function of the available ventilation data. The second chapter discusses program modifications, whose necessity or desirability was, during the application, discovered. The following five chapters, which comprise the major portion of the report, give the detailed description of the program application on the five mines. For every one of the selected mines, the ventilation system, the source of the used ventilation data and their preparation for computer simulations are outlined. Based on data for the airflow distribution solely, fumes concentrations in the mines are calculated for several assumed fire locations. Based on data for airflow and pressure distributions, ventilation disturbances caused by fires as well as the resulting fumes concentrations and temperatures are determined. The consequences for escape routes and the possible means to keep them free of fumes are discussed. To investigate the capabilities of the program, other contaminant sources and other potentially dangerous ventilation factors, like fan failures and changed surface temperatures, are simulated also. The results of the calculations have been entered into ventilation plans which makes them easier to scrutinize. All significant computer printouts have been attached.

Jan 1, 1981

The Small Pebble Process for Reducing Ball and Power Consumption in Secondary Grinding Ball mills are used widely for secondary grinding. A mixture of ball sizes can be used to optimise grinding efficiency, but the use of balls smaller than about 30 mm in diameter is not normally viable, particularly when alloy steel is required. Preliminary testing of the grinding efficiency of various combinations of 40 mm steel balls and crushed stone in the size range 7 to 25 mm was carried out in a 300 mm diameter mill, which has accurate power measurement.The primary interest was to assess the potential benefit of adding small pebbles (from a primary circuit crusher or mill) to a secondary ball mill, to reduce ball consumption and to improve grinding efficiency. The optimum proportion of pebbles was found to be about 25 per cent by volume. This mixture produced about the same amount of fines as balls alone, but with lower power consumption, due to the lower density of the pebbles. The net result was a 12 per cent saving in power and a 25 per cent saving in ball consumption. The production of fines was partly due to pebble wear. The use of portions of 15 mm balls, (ceramic and steel), was also tested for comparison. A few batch pilot-scale tests were conducted in a 1.2 m diameter, 0.31 m long mill to test the viability of the pebbles at a larger scale. The pilot-scale tests confirmed the reduction in power and that the rate of production of fines was the same as that obtained with balls. The same residence time was used and this implies that pebbles can be added to an existing full-scale ball mill, with no loss in capacity. Samples of secondary mill feed and pebbles were obtained from a copper mine and the steady-state consumption of pebbles was determined by locked-cycle laboratory-scale tests. These tests demonstrated that mill power could be reduced by up 13 per cent and that the consumption of 40 mm balls could be reduced by up to 38 per cent, while maintaining the same throughput and product size. The rate of pebble addition was about 4 per cent of the primary circuit feed rate. Application has been made for patent protection.

Sep 13, 2010

Fine Coal Evaluation by Gravity Methods

Sep 13, 2010

By William G. Pariseau

The research reported here concerns a four year study of the rock mechanics aspects of two underground hardrock mine study stopes. The first study was conducted at Anaconda Minerals Company's Carr Fork Mine near Tooele, Utah. The second study was conducted at the Homestake Mining Company's Homestake Mine In Lead, South Dakota. Both case studies were cooperative efforts of mining company personnel, the Spokane Research Center of the Bureau of Mines and the Department of Mining Engineering, University of Utah. Large diameter (6 1/2 In.) blastholes were an integral part of the stoplng method at each mine. A true vertical crater retreat (VCR) method was used at the Homestake Mine, while a vertical bench mining method (VBM) was used at the Carr Fork Mine. VCR and VBM methods were developed In the 1970's; they offer significant productivity gain and are now used throughout the world. The new technology, however, brings with It a requirement for more sophisticated engineering design and control. Since there are no personnel in a VCR or VBM stope, all ground control Including dimensioning of stopes and pillars and the layout of cable bolt assays or other artificial support must be done in advance of production blasting. Accordingly, the objective of the research study was the establishment of a procedure for optimizing stops and pillar sizes. The approach taken was In each case a combination of mine measurements of the study stope response to mining, laboratory testing for rock properties and In situ stress measurements of the premining stress field, and theoretical calculations of the study stope response to mining. All calculations were done with the UTAH-II finite element computer program. Simulation of the blasting sequence gave a correlation of 0.88 between measured and calculated extensometer readings (Incremental relative displacements) at the Carr Fork Mine where other 30 Instrumentation boreholes were used to monitor the test stope response. A correlation of 0.84 was obtained at the Homestake Mine where 19 instrumented boreholes were used for monitoring purposes. These high correlations validated the computer mode and calibrated It for rock mass properties. The calibrated model was then used In parametric studies of alternative design layouts.

Jan 1, 1985

By Leslie F. Sawatsky

Each potential oil sands developer deals with the question of optional sources of raw water to supply large water demands that range from 50 to 80 million cubic metres per year for each of six existing and planned developments. The Athabasca River currently supplies nearly all of the water to the existing mines via conventional bank intakes, which has resulted in some concern over the effects of reduced river flows. This paper describes the various water supply options, and the likely scenario for future oil sands water supply projects. Various water supply options have been suggested including Athabasca River water via infiltration galleries, groundwater, combined Athabasca River water and alluvial groundwater using wells (i.e. bank filtration systems), diversion of tributary rivers, utilization of large lakes in the region and pumping from other large rivers in the region. Investigations show that the size of river catchment needed to support raw water usage by a typical oil sands mines exceeds 5,000 km2 eliminating all tributary rivers that are located in the oil sands region except those rivers with large drainage areas like Firebag and MacKay Rivers. Lakes cannot be used as a source of supply due to large water deficits for smaller lakes and the large cost of sourcing water from a lake as large as Lake Athabasca. A groundwater source alone would not likely meet the large water demands. River intakes on the Athabasca River will likely continue to be the most practical water supply option for oil sands mines north of Fort McMurray, although various types of Athabasca River intakes are possible. Existing intake systems include screened riverbank intakes, forebay intakes, and river bottom intakes. Infiltration galleries are not feasible for most sites, though some bank-filtration-type systems using high capacity wells may be an option if there is sufficient thickness of high-permeability alluvium at a suitable location in the Athabasca River valley.

May 1, 2004

By M. Tangstad, H. Brun, P. Calvert, A. G. Lindseth

In 1999, Eramet bought the ferromanganese plants in Porsgrunn and Sauda (Norway) and Marietta (USA). With an ownership in the Comilog mine, the plants will operate with a high amount of Comilog ore. The properties of Comilog ore are reviewed and compared to a number of industrial operations. Important ore properties are chemical and mineralogical analyses, CO reactivity and mechanical strength. The advantage of Comilog ore is its contribution to lower energy and coke consumption. However, special precautions must be taken regarding the amount of fines and water introduced in the furnace, as Comilog ore is more porous compared to other Mn ores.

Jan 1, 2004

By Charles F. Jackson

Gold mining is a subject that not only appeals to the popular imagination but has vital importance to the world's economic structure. However, a discussion of the use of gold as a medium of exchange, and a basis for credit between nations and for monetary systems is not within the scope of this paper. The importance of gold in carrying on the commerce of the world, the present supply and rate of production, the probable trend of future production, the probable future requirements, and related subjects have recently received much attention from bankers and economists, and many articles on these subjects have been published. During slack periods of base-metal production due to falling prices, accompanied by scaling down of base-metal mining operations and often by the closing down of at least some mines, there usually result revival of interest in gold mining, search for previously undiscovered deposits, and reopening of some old gold mines.

Jan 1, 1932

By D Hill

In the Ngakuru area zeolite deposits occur in late Quaternary lacustrine vitric tuffs of the Ngakuru Formation and two of the deposits are being mined. The Ngakuru Formation overlies the Ohakuri Ignimbrite dated at c. 240 ka, and is overlain by younger alluvial sands and gravels. Individual zeolite deposits contain 50 - 80 per cent zeolite over a thickness of up to 45 m in thinly stratified vitric tuffs and are localised along NE-trending normal faults. Glass shards in the tuffs are replaced by the silica-rich zeolites mordenite and clinoptilolite. Amorphous silica (opal A), opal-CT, Kfeldspar and smectite are also present. The zeolites and other minerals are very fine grained (<10 8m), with open meshes of crystals that result in high porosities (52 - 70 per cent) in mordenite-rich tuffs. Zeolitic tuff samples typically have cation exchange capacities of 80 to 110 meq/100 g and internal surface areas of 25 - 58 m2/g, which combine to give high liquid and odour absorption capacities. The first zeolite deposit (Mangatete) was found in 1992, and this and the Twist Road deposit are worked by quarry benching into the side of hills. The zeolitic tuffs are dried and crushed to produce a variety of products including adsorbents for soaking up oil/chemical spills and animal wastes, animal feed supplements, water treatment, and sports turf and slow release fertiliser. The Ngakuru zeolite deposits formed at shallow depth (<100 m) along fault zones from reaction of glass-rich tuff beds with groundwater-diluted geothermal water during the late Quaternary, and are as young as 8500 yr BP from 14C dating of plant material in sinter associated with the Mangatete deposit.

Jan 1, 2005

New developments in the pipe conveyor and belt are advanced to address the growth in the capacity, length and complexity of pipe conveyor systems. Improved belt construction can offer better stability during horizontal curves and resistance to twist. Low rolling resistance rubber compound can significantly lower the power consumption and belt tension, producing capital and operation cost savings. Dynamic analysis, when used to analyze the conveyor?s starting and stopping behavior, can improve the design and reliability of long overland pipe conveyor systems. For these three aspects, technical backgrounds and field installations as examples are discussed in this paper.

Jan 1, 2012

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 J. T. McLendon

As part of its research project in developing improved refractory materials for metallurgical applications, the Federal Bureau of Mines obtained hot modulus of rupture data at 1,500°,1,550°, and 1,600° C on samples of 13 refractory periclase materials produced from seawater, lake brines, and natural magnesite. The periclase samples also were characterized to establish chemical and mineralogical composition and microstructure. The results indicated that a high MgO content does not necessarily assure good hot strength and that an optimum and varying CaO-Si02 ratio exists for each individual periclase sample.

Jan 1, 1979

Research on the Thermodynamics of Siderite Roast Decomposition and the Experiment of Magnetic Roasting-Separation

Sep 13, 2010

By F. D. DeVaney

Metallurgists and coal-washing engineers have used heavy liquids for years in studying the characteristics of ores and coal. By such means true separations can be made between the various specific-gravity increments in the materials examined. To use of heavy liquids has permitted determination of the possible grades of tailings and concentrates by specific-gravity methods on any particular size, and therefore the size to which the ore must be crushed to free the valuable material. The simplicity of float-and-sink separation and the high degree of efficiency attained in the laboratory are factors that commend the method for commercial concentrations.

Jan 1, 1940

By R. V. Ramani

This report is volume 2 of an eleven-volume final report for a Grant completed by The Pennsylvania State University for the Bureau of Mines to develop a dynamic general purpose computer simulation model for underground coal mining. The simulator developed under the Grant has a wide range of possible applications in the design and evaluation of underground coal mining systems from the standpoints of health and safety, productivity, and mine environment. The Master Design Simulator consists of nine free-standing function-oriented subsystem models linked together into an integrated, comprehensive model of an entire mining system. The subsystems comprising the Master Design Simulator include geology and reserves, methane generation, roof support, subsidence, production, rail haulage, cost, water generation, and ventilation. This volume of the final report describes the Geology and Reserves subsystem of the Master Design Simulator. The two functions of this subsystem are: 1) the design of a geological data library to provide input to the other subsystems of the simulator; and 2) the calculation of coal reserves and associated values and grades under various user-specified conditions. The subsystem uses a weighted moving average method to interpolate between the borehole values, and provides output in report format, graphical plots and/or storage on magnetic tape or other storage devices for later retrieval. The application of the subsystem as an independent model with test results and comparisons with other methods of computing reserves is also presented. The appendix comprises a users manual for the model, and includes a program listing.

Jan 1, 1974

By M. S. Fleming

The objective was to evaluate central lubrication systems for potential use on underground mining equipment. Previous use on continuous mining equipment resulted in poor system performance because of improper selection of lubricants, component failures, and an inconsistent delivery of lubricant to the bearings. The principles and operational characteristics of systems are reviewed and evaluated, and it was concluded that systems are available which can provide reliable central lubrication if properly applied, installed, and maintained. The procedures for applying a system to a continuous miner are discussed. Investigation revealed the lack of significant information on lubrication-related equipment failures and injuries related to maintenance and repair operations, the lack of significant failure rate data for central lubrication system components, and the lack of performance standards for central lubrication systems and components. To continue the development of systems for underground mining equipment it is recommended that a data bank on failures and reliability for equipment with and without central lubrication systems be created, and standardized specifications and performance criteria be developed for central lubrication systems and components which will be used on underground mining equipment.

Jan 1, 1979

By B. M. Larsen, J. W. Campbell

Several articles have recently been published discussing the conditions necessary for accurate measurements of temperatures in the open-hearth steel furnace. In the course of a study of refractories service conditions in steel furnaces, the present writers have taken temperatures in several open-hearth shops in the Pittsburgh district. The conclusions, as to conditions necessary for accurate measurements of temperature, are somewhat at variance with those of other investigators. The subject is closely connected both with the close control of steel-making and the prevention of overheating of the silica refractories used in roofs and walls. It is becoming more and more important to obtain furnace temperatures of fairly definitely known accuracy. At present, the most useful instrument for such measurements is the disappearing-filament type of optical pyrometer. This method of measurement has formed the basis of most other discussions on the subject and was also used by the writers. Previous Investigations In 1916, Burgess' made perhaps the first systematic series of measurements in steel furnaces. The emissivity figures of 0.40 for liquid steel and of 0.53 to 0.65 for liquid slags had been determined by the Bureau of Standards and were used by Burgess in this work. These correction factors are still being used and are regarded as fairly accurate, so that the tapping and teeming temperatures on metal streams given by Burgess should be very nearly correct. Most of his temperatures of furnace roofs and slag surfaces were taken while flames were present in the furnaces and include a few roof temperatures above 1700' C. (3100' F.).

Jan 1, 1927