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By K Niyomjinda, B Etschmann

Chatree Gold Mine is currently the only modern day gold mine operating in Thailand, and is situated approximately equidistant from Chiang Mai in the north and Bangkok in the south. Environmental guidelines set by the Thai authorities require Chatree Gold Mine to achieve a Total Cyanide level of 20 ppm or less in the process plant discharge slurry stream prior to release into the tailings storage facility. This paper describes both the initial difficulties faced in achieving compliance on this limit utilising the conventional INCO SO2/Air cyanide destruction system and the subsequent process improvements initiated to both the leaching process and the standard INCO process to achieve the current compliance levels of approximately 99/100 shifts. Improvements were focussed on the dual aspects of reducing the formation of WAD cyanide and ferrocyanide species in the leaching circuit coupled with process changes to improve removal of the ferrocyanide species from solution during the cyanide reduction stage.

Jan 1, 2004

By John J. Murray, Michael T. McRae, Michael A. Krulc, Kathy L. Schuler

The San Vicente Pipeline Tunnel Project involves the construction of an 8.5-foot-diameter water pipeline in an 11 mile tunnel in San Diego, California. The tunnel is located in extremely variable geologic conditions of strong granitic and volcanic rocks, weak sedimentary rocks, abrasive conglomerates, and mixed face conditions. One reach of the tunnel is a 5,200-foot mixed face reach that includes Friars Formation Conglomerate overlying granitic rock. Due to the variable ground conditions in this reach, the use of a TBM was deemed too risky and the contract documents required drill-and-blast and hand mining methods. Although it was not required, the contractor elected to construct this reach using NATM methods. This paper describes the geology of the 5,200-foot mixed-face reach, the design evaluation, and the construction challenges faced on this project.

Jan 1, 2007

By Rudolph P. Frizzi

"Abstract Pile design for building structures in the United States is typically performed by: 1) investigating and assigning engineering parameters to the respective ground bearing materials, 2) calculating ultimate pile to ground (geotechnical) capacity which is then reduced by a Safety Factor deemed appropriate by a registered Design Professional thereby arriving at an allowable pile geotechnical pile capacity, and 3) determining the required pile structural section using allowable pile section material properties. It is advantageous to use a Working Stress Design Method (WSDM) approach as one system of loads (service loads) are used in both the geotechnical and structural evaluation. There are a variety of methods used to determine the ultimate and allowable geotechnical capacity, and Building Codes often require a registered Design Professional to determine the appropriate method(s) and capacities. The International Building Code is the Code typically referenced in building design and construction in the United States. Structural design usually follows Building Code requirements and Allowable Stress Design (ASD) procedures. As design of the overlying structure typically follows a Strength Design Method (SDM) approach using factored loads, in some cases piling is first designed for pile-to-soil interaction using service loads, followed by evaluating the pile geometry for factored loads. Construction is the finalization and implementation of the designed piling. As such, project-specific technical specifications are typically developed by a registered Design Professional such that a project Owner can bid, buy, and instruct a Contractor as to the desired piling work and acceptance criteria. There are several Industry groups, including DFI, PDCA, ADSC, and ACI that provide guidance documents which the registered Design Professional can refer to in developing the piling technical specifications. It is the author’s opinion that the registered Design Professional is best suited to observe and verify the piling installation; many Building Departments require verification and documentation by a registered Professional as a condition of final acceptance.INTRODUCTIONPile design for building structures consists of: investigation, design, specification, and verification. In major metropolitan areas within the United States, Building Codes typically identify minimum requirements for each of the above steps. The International Building Code (ICC, 2012) is the Code typically referenced in building design and construction in the United States. Recognizing the ground conditions as well as piling construction means and methods can vary on a site-by-site basis, latitude is given to the registered Design Professional and Contractor to optimize the piling system for the respective project conditions. Field testing and quality control / assurance measures are typically implemented to verify the design intent is attained for the production pile elements."

Jan 1, 2014

By Richard E. Gray

Subsidence due to coal mining is poorly understood by non-specialists. This has led to numerous misconceptions and myths based on limited observations and lack of knowledge. The three most common are: 1. Mine maps are inaccurate. 2. Deep mines are not a problem. 3. If no subsidence has occurred for many years after mining, there is no risk of future subsidence. Maps are important during mining and most are carefully prepared. Future use to evaluate conditions at mine level often includes drilling to confirm what the map shows. Usually, little or no effort is made to tie the surface survey of the property to the mine survey, to conduct a well designed drilling program to confirm the mine map, or to drill test borings vertically. When a mine entry is encountered rather than a coal pillar, or vice versa, and conditions at mine level appear different than anticipated, the first reaction is the mine map is inaccurate. The idea of a safe depth from subsidence is often based on the false premise that mining results in sufficient breakup of the overlying rock strata that bulking compensates for the coal extracted. The safe depth idea first appeared in the literature about 1880 and remained prevalent well into this century. Sadly, it is still encountered. The modern understanding of fragmentation of the immediate mine roof with the overlying beds sagging down on the broken roof rock was first described in 1900. With full extraction mining, either longwall or retreat room and pillar, surface subsidence occurs regardless of the depth of the mine. Subsidence over longwall mines at depths of 2000 feet can be 90 percent of the mined seam thickness. Numerous studies of undermined sites conclude that mining occurred many years ago and since no subsidence has occurred, there is no risk of future movement. This is true if sufficient coal pillars have been left to support the overlying strata. However, every year subsidence occurs over mines that have been closed for 100 years or more. In a study of subsidence incidents over the Pittsburgh Coal, the senior authors found that 50 percent of the incidents occurred above mines that had been closed for at least 50 years and 10 percent over mines closed for at least 80 years.

Jan 1, 1996

By Allan Sylvester

This paper will discuss the design, construction, and performance of the support of excavation on the San Diego State University LRT Station. The vertical elements of the system include drilled secant piles and drilled soldier piles. We will discuss the geo-technical characteristics, design and construction considerations, loading criteria, construction techniques, schedule constraints, and performance of the pile and support of excavation systems. In consideration of the conference theme, there will be a discussion of the successful accomplishment of meeting the interim milestone dates of the Contract. The project team cooperatively worked to design and install approximately 1,100 drilled secant and soldier piles as well as excavate and install the balance of the support of excavation elements in such a manner as to minimize the disruption to campus students and operations.

Jan 1, 2002

Few, if any, reliable thermodynamic data are available for the activity of tin oxide in slags. In this work, the activity of the oxide in silica saturated iron silicate slags has been measured at 1573 K using the equilibrium Sn (alloy) + Y2O2-SnO (slag).Slag and a Ag-Sn alloy were sealed in a zirconium oxide crucible to prevent the escape of volatile tin oxide, and the oxygen pressure at equilibrium measured in situ using the zirconium oxide as a solid electrolyte. Activity of tin was calculated from known data for the Ag-Sn system and activity of tin oxide calculated from free energy data. The results have been extrapolated to predict the industrially important distribution of tin and iron between Fe-Sn alloy and iron silicate based slags.

Jan 1, 1983

By T. Soejima

In recent years, there has been a tendency in the field of foundation piling works to utilize piles of greater bearing capacity in order to meet increasing height and weight of modern building as a means of saving of piling cost. To satisfy these requirement, a new technique for large diameter bell bottom cast-in-place piling has been developed utilizing multi-head reverse circulation drilling system.

Jan 1, 2010

By S. R. Zimmerley

As a result of the drilling program of the :Mining Division, Bureau of Mines, large amounts of manganese ores have been blocked out in the Drum Mountain District of Utah. The ores, as mined, would not be acceptable for the production of ferromanganese, and this investigation was made to determine their amenability to concentration by ore-dressing methods and the amount of

Jan 1, 1942

By S. R. Zimmerley

As a result of the drilling program of the Mining Division, Bureau of Mines, large amounts of manganese ores have been blocked out in the Drum Mountain District of Utah. The ores, as mined, would not be acceptable for the production of ferromanganese, and this investigation was made to determine their amenability to concentration by ore-dressing methods and the amount of

Jan 1, 1942

By A. T. Iannacchione

Underground mining of stone in the US is increasing, as is the depth of overburden above the mines. Data gathered from mine visits, maps, discussion with operators and numerical simulation have been used to investigate pillar design and recommend safe practice. Many pillars have slender shapes with relatively large adjacent mine openings: width-to-height ratios range from 0.54 to 3.13 and extraction ratios from 0.56 to 0.91. The pillar material is often very strong and average overburden only 80 m, but occasional failure due to excessive local stress has occurred where pillar size had been unintentionally reduced, overburdens were greater than 200 m, width-to-height ratios were less than 1.25 or extraction ratios were greater than 0.83. Pillars with width-to-height ratios of less than 1.5 appear more likely to fail under excessive stress. When width-to-height ratios fall below 1.0, defects such as through-running discontinuities can have a significant influence on stability. Dip, orientation and material properties are also important

Jun 21, 1905

By C A. Feebrey, R A. Duncan

The Ebor Volcano in north eastern New South Wales is an eroded example of a central-type intraplate volcanic-intrusive complex. It is of Miocene age (19 - 20 Ma) and has similarities to other central-type volcanoes in eastern Australia which may represent manifestations of sub-lithospheric hotspot activity. Thick lava flows are exposed around the Great Escarpment and are dominated by a tholeiitic basaltic suite, ranging from ol-tholeiite to qz-tholeiite to icelandite with ages of 19.2 - 19.6 Ma. On its western edge, the tholeiitic lava suite probably overlies remnants of basanite flows belonging to the Eocene (~48 Ma) Doughboy province, but elsewhere, minor alkaline basaltic lavas may be coeval with the tholeiitic suite. Several felsic bodies were emplaced into the volcano at ~19.0 - 19.2 Ma and include subalkaline and peralkaline types. The Crescent Complex is a Miocene-age, strongly differentiated mafic to felsic intrusion in basement rocks and centrally located in pre-erosion reconstructions of the Ebor Volcano. It is interpreted to be a major feeder for the tholeiitic lavas based on age and composition. Evolution of the dominant tholeiitic suite proceeded from a parental ol-tholeiite magma, through qz-tholeiite, icelandite and small volumes of felsic rocks by fractionation of plagioclase, olivine, clinopyroxene and titanomagnetite, accompanied by enrichmentof SiO2, SFeOlMgO, alkalies and HFSE.

Jan 1, 1995

By M K. de Brodtkorb

Late Cenozoic ore deposits æPrecious and base metal-richÆ and æSn-Ag-polymetallicÆ ofNorthern Puna are associated either with Middle Miocene dacitic volcanic-dome complexes or with Upper Miocene dacitic-andesitic volcanic centres.   Ore mineralogies and their related volcanism are discussed. A strong link is observed between the Cenozoic Metallogenetic Province of Northern Puna and the Southern Bolivia Tin and polymetallic provinces.  

Jan 1, 1995

By J. A. McLennan

Nickel laterite deposits are typically formed from tropically weathered mafic-ultramafic complexes. The resulting nickel concentration is found within soil horizons and is mineable with regular dozer units. At the time of mining, digging elevations are needed at selective mining units (SMUs). Moreover, for mine planning, the costs due to dilution and lost ore require mining elevations to be specified. A conditional simulation approach is used to calculate ?optimum? SMU mining elevations. Multiple realizations of the ore base surface are simulated. For a single bottom surface realization, dilution and lost ore costs are calculated over the entire vertical extent of each SMU. The optimum mining elevation is the elevation where the lowest summed cost of ?accepting dilution? and ?wasting ore? occurs. The reported SMU dilution is the cost of mining the volume of waste located below the bottom surface and above the optimum mining elevation and the reported SMU lost ore is the cost of not mining the volume of ore above the bottom surface and below the optimum mining elevation. For all ore bottom surface realizations, optimum SMU mining elevations and their associated dilution and lost ore costs are calculated and compiled to represent production uncertainty.

Apr 1, 2005

By A. Mazzucato

This paper presents the experimental results of driving and load tests on an instrumented pile driven into a test pit filled with fine homogeneous sand.

Jan 1, 2010

By David A. Larson

Preliminary laboratory experiments have been conducted by the Bureau of Mines to define the influence of bit geometry on methane ignitions as a step toward establishing safer mining-machine operating parameters. The experimental system was designed to simulate the operation of a continuous mining machine, using a drum-type cutterhead of normal diameter with a narrow cross section, permitting full-diameter drum cutting tests to be run on material representative of sandstone lenses (or inclusions) in coal seams. Two conical bit types were tested at shallow depths of cut with three drum speeds. Bits that rotated in the mounting block during testing did not produce ignitions. The ignition frequency for used bits was three to four times greater than for new bits at the same kerf depth.

Jan 1, 1983

By T. C. Davis

Nine organic derivatives of fluorine, silicon, boron, and aluminum were purified for thermodynamic studies using distillation, zone melting, and gas liquid chromatography, The unusual properties of these compounds required the development of special techniques for handling and purification. To determine purities of purified samples, new techniques for analyzing spectral data were developed.

Jan 1, 1965

By John E. Wiegand

This study will discuss the AMAX Coal Co., Penndiana Pipeline Project, which was conducted in conjunction with the following parties: AMAX Coal Industries, (U.S.B.O.M.) United States Bureau of Mines, (I.D.O.R.) Indiana Division of Reclamation, Ohio Valley Pipeline, Inc., New Mexico Tech, and ourselves, VIBRONICS, INC., Evansville, Indiana. The purpose of this study was to find a safe vibration level for active gas transmission pipelines near surface coal operations.

Jan 1, 1994

By M. Wickham

Design of an open pit backfill requires an understanding of highly varied processes including slope stability, hydrogeology, pit lake chemistry, climate, runoff, and mine waste behavior. Dynamic systems modeling (DSM) provides flexibility to the designers of open pit backfill, allowing them to directly integrate many different physical processes and varying levels of complexity. DSM also provides for the efficient application of uncertainty analysis to define a range of possible results, the sensitivity of the results to uncertainties in model inputs, and the value of additional data. This paper presents the results of an analysis using DSM to evaluate a pit backfill design at an Arizona mine. The objective of the partial backfill was to stabilize an active slope that threatened facilities adjacent to the pit. DSM was used, in part, to develop a pit lake water balance model for evaluating the influence of the backfill on the ability of the pit to maintain passive hydraulic containment of groundwater and surface water inflows and for evaluating costs for various backfill scenarios.

Jan 1, 2001

By G. Wahl, H. Danilkewich, T. Mann

Developers of advanced mining projects face the challenge of how to craft a “Request for Proposal for a Feasibility Study” that will result in bids that are comparable and will lead to a successful execution of the study. Mining engineering consulting firms are challenged by “Request for Proposals” that may consist of a limited description of the Scope of Services and other items, which could present difficulties in the subsequent financing and/or development of the project. Changes in international disclosure requirements have also changed the landscape on how resources and reserves are reported by introducing new disclosure requirements and concepts such as qualified persons. This paper lays out a strategy for preparing a Feasibility Study “Request for Proposal” based on the experiences of a mining engineering consulting firm working on a diversity of projects around the world, and in light of the recent changes in international reporting standards for reserves.

Jan 1, 2002

By Manuel Gomez

Bituminous coals having maximum fluidity values in the 40- to 25,400-dial-divisions-per-minute (ddpm) range were carbonized in a continuous, entrained-bed reactor. Carbonization was conducted in an 8-inch diameter, vertical reactor at temperatures from 955° to 1,345° F and at air-to-coal ratios ranging from 4.63 to 16.12 scf/lb of moisture-and ash-free coal charged. Carbonization rates from about 118 to 360 lb/hr, as-carbonized basis, were examined. It was demonstrated that carbonization temperature and air-to-coal ratio must exceed minimum values for continuous operation. Within the operating conditions discussed, highly fluid bituminous coal was carbonized to produce tar and nonagglomerated char. The yield of tar ranged from 21.3 to 38.9 gallons per ton and the char yield ranged from 1,109 to 1,563 pounds per ton, all units expressed on a moisture-and ash-free basis. It was demonstrated that the maximum fluidity and the average size of the coal along with the air-to-coal ratio and the carbonization temperature act together to influence the carbonization product yields and certain properties of the products. Prediction equations were developed from the data for product yields and selected properties of the char, tar, and gas.

Jan 1, 1968