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By Nicola Della Valle

The Singapore Land Transport Authority (LTA) is currently expanding capacity by extending their Metro system from South of the city to the North East end of the island. The scope of Contract 704 involved excavating a long reach of tunnel which had a complex rock/soil interface comprised of fresh granite overlaid by clayey sand. Two 6.5 m diameter Earth Pressure Balance (EPB) TBM’s were used to bore the tunnels. These machines were designed so that both hard and soft rock could be excavated. The cutter head was equipped with a combination of both rippers and disk cutters. Soil conditioning was achieved by delivering foam through a multiple port injection system. This very irregular profile of the interfaces posed many challenges to the equipment and the people.

Jan 1, 2001

By Charles W. Daugherty, Eugene B. Waggoner

In the construction of recent subsurface projects, particularly mined openings and transit systems, it has been apparent that final costs were often greater than first expected. Because many overruns result from alleged differing site conditions, there was reason to suspect that pre-bid geotechnical investigations were inadequate for predicting subsurface geology. In 1982, nine federal agencies involved in constructing underground facilities funded the National Academy of Sciences' U.S. National Committee on Tunneling Technology (USNC/TT) in an effort to evaluate and clarify the relationship between geological knowledge and construction costs. That committee formed the special Subcommittee on Geological Site Investigations, which spent more than two years studying underground projects by examining contract documents and geologic reports, making site visits, and interviewing owners, designers and contractors. The study ultimately encompassed 84 mined tunnels and chambers and three deep shafts in the United States and eastern Canada. Data collected on geologic exploration, design and construction were analyzed and conclusions reached concerning whether and how site investigations need to be improved. The results of the study are published in two volumes by the National Academy of Sciences. Due to the recent completion date of the main report, it was not possible to prepare a summary for inclusion in the RETC Proceedings. However, the complete two-volume report, "Geotechnical Site Investigations for Underground Projects," can be obtained by writing or calling: U.S. National Committee on Tunneling Technology National Academy of Sciences 2101 Constitution Avenue, N.W. Washington, D.C. 20418 (202) 334-3136

Jan 1, 1985

By John W. Sweeney

Florida is usually thought of as a vacation State, not a mining State, yet Florida has been the leading producer of phosphate rock in the United States for 85 consecutive years and in 1978 supplied over 80 percent of the national output and over 30 percent of the world's output. It is estimated that the Central and South Florida phosphates contain 412,800 short tons (374,000 metric tons) of U308, that 115,000 short tons (104,000 metric tons) of U308 will be contained in the wet-process phosphoric" acid procsssed in the United States through the year 2000, and that 54,000 short tons (49,000 metric tons) of U308 will be available from Florida. In 1978, two companies in Florida and one in Louisiana went on-stream recovering uranium oxide from wet-process phosphoric acid and three others started construction of U308 extraction facilities. These six companies will have the capacity to recover 2,137 short tons (1,900 metric tons) of U308 annually in 1980, which will account for about 15 percent of our domestic requirements.

Jan 1, 1979

By J. Drelich

The flotation limit of fine particles has been re-examined based on the effect of bubble size on contact angle, and a new surface chemistry-limited relationship describing the minimum particle size which can be floated is proposed. In this analysis the critical value of bubble-solid contact radius (re) for which there is no effective attachment between particle and bubble has to be determined. The values of re determined by extrapolation of our experimental data for contact angle versus bubble-solid contact diameter permit the prediction of the flotation limit of methylated quartz particles, with fraction-al coverage of trimethylsilyl groups from 0.07 to 0.51. The limit of fine particle flotation as determined by this theoretical approach agrees well with experimental data reported in the literature.

Jan 1, 1994

By S. Norman Kesten

The Resource Conservation and Recovery Act, commonly known as RCRA, which amends the previous Solid Waste Disposal Act, was signed into law on October 21, 1976. Members of the mining industry began their contacts with EPA in this area two to three years before the Act finally was passed, and that seemed and probably was all to the good. We reviewed and commented upon their studies and in general tried to acquaint them with the peculiarities and the uniqueness of the wastes generated by our industry, of which they were abyssmally ignorant. I suppose we thought that through the bureaucracy we might have some influence upon the provisions of the solid waste legislation that was being bandied about on the hill. Certainly the industry, in general, did very little direct lobbying, as I recall, and there were several reasons for that. For one thing we conceived that the legislation was aimed at the chemical industy and believed that if their people looked after their interests, ours would be safeguarded automatically. Also, the Federal Land Policy and Management Act (FLPMA) was heating up at the same time and, in fact, was signed into law on the same day. In addition, a great deal of lobbying activity was required by amendments of the Clean Air Act and Federal Water Pollution Control Act that were being put together in Congress. These were conceived to be of far greater importance to our industry than a bill to control mostly chemical wastes and, in fact, new bills in both areas became law the following year. Finally, the solid waste bill, RCRA, was patched together by committee staffs over one weekend and was reported out by a conference committee rather hurriedly. Some little goodies about mining were almost after-thoughts in this process.

Jan 1, 1981

By D. Y. Jiang, X. S. Tan, S. S. Peng

Expansion strain and stress that exist in floor rocks and that are due to the presence of water, were derived from a basic theory of mechanics. The results indicate that water stress and strain are the important factors that cause failure of the floor rocks and induce floor heave.

Jan 1, 1994

By V. Rajaram

R.C. Rex, Jr. V. Rajaram's paper does not accurately reflect the status of Eastern oil shale development as it stands today. Today, there are numerous firms and research organizations pursuing development of the Eastern oil shale resource. Details of the current projects can be found in the symposium proceedings for the 1985 Eastern Oil Shale Symposium held in Lexington, KY, in November 1985. Additionally, the comparison of the Paraho and HYTORT processes is invalid because the HYTORT process design used it not an accurate representation of the HYTORT process. I will briefly address this point. It is disconcerting to see the author reference hydroretorting work conducted at the Institute of Gas Technology (IGT) (circa 1978) in the introduction, which indicates hydroretorting (the HYTORT process concept) yields of up to 250% of the Fischer Assay oil yield, and then turn around and base the remainder of the paper on the 1981 "Synthetic Fuels From Eastern Oil Shale Report," which depicts the HYTORT process as yielding only 115% of Fischer Assay. Indeed, work conducted at IGT to 1981 indicates commercial oil yields for the HYTORT process would be in the range of 200% to 210% of Fischer Assay. A more thorough literature search by the author would have yielded a 1981 publication by Schora et al., entitled "Update on the HYTORT Process" presented at the Symposium on Synthetic Fuels From Oil Shale in Nashville, TN, October 1981. This paper thoroughly discusses the shortcomings of the referenced study with respect to the HYTORT process. For the interested reader, I can also recommend a June 1984 report entitled "An Economic Comparison of Five Process Concepts for Using Eastern Oil Shale," published by Los Alomos National Laboratory (LA-10106-MS, Parkinson et al., NTIS No. DE84-015981). This study applies a realistic HYTORT design (circa 1982) and indicates that HYTORT is the most econom¬ical method of processing Eastern oil shales (about $20/bbl less than Paraho). Additionally, completion of the HYTORT feasibility study in June 1983 by Phillips Petroleum Co., Bechtel Group Inc., HYCRUDE Corp., and IGT has resulted in development of designs that will make the use of HYTORT on Eastern oil shales even more economic. HYCRUDE Corp., a second-tier subsidiary of IGT, is involved in commercialization and licensing of the HYTORT process and is active in efforts to develop the Eastern oil shale resource. As such, I am disappointed to see outdated material that has the potential for adversely affecting development of Eastern oil shale resources published in MINING ENGINEERING. I can only hope that this response will serve to mitigate any negative opinions that may have been formed. Today, activity in commercializing Eastern oil shales dominates the oil shale scene in the US and indicates a realization of the potential for these shales. Reply by V. Rajaram I appreciate the updates on the HYTORT process provided by R.C. Rex, Jr. I hope that Hycrude's work will lead to the funding of a pilot plant to demonstrate that yields of greater than 200% of Fischer Assay can be achieved in a commercial plant using eastern US oil shales.

Jan 9, 1986

By George E. Aiken, B. R. Jr. Waples

INTRODUCTION In this paper the author will attempt to bridge from the paper work of design and engineering to the reality of implementation. Certain facets of construction are constant to a successful project, no matter the level of technical complexity. Basic to timely, low cost construction are the people assigned to the project. Construction is not accomplished by robots, computers, or speeches; but rather by people. People do however require the avail- ability of equipment and communications to properly complete the work. ORGANIZATION Good organization is the basic requirement of a well implemented construction project. For this paper the author will suggest an organization chart as well as an activity listing that together support the construction activities. There is little difference in the activities or functions needed to construct a small plant or a large one. It is a matter of how much time an individual has to spend on an activity that determines the structure of an organization. The difference between a large and small plant construction job is often described as the multiple hat versus the single hat philosophy. As an example, a resident construction manager on a small job might be the manager, the field engineer, the scheduler, the estimator, and the procurement manager. At some time during a construction

Jan 1, 1986

By M. P. Saunders

A comprehensive, site specific water management plan is of primary importance to the successful implementation, operation and decommissioning of any mining project. Formulation of a plan requires an orderly planning process consisting of identifying problems, establishing planning criteria based on the guidelines and requirements of regulatory agencies, and an iterative procedure of identifying, investigating, and evaluating plan elements and alternative plans. A typical uranium surface mine operation consists of a mine pit or pits, spoil pile areas, crusher, processing plant, and tailings disposal area. A water control plan addresses the problems of diversion of natural runoff from undisturbed areas around the mine; and diversion, collection, and treatment of runoff from within the mine area. A water control plan is required to determine the location and size of appropriate control and detention structures; their cost; and the schedule for permit activity, design, and construction. The plan must be formulated to meet the requirements of both the State and Federal regulatory agencies.

Jan 1, 1981

By Charles Stone, Madan Naik, Drupad Desai, Karel Rossler

Planning of New York’s new subway line dictated the location of shallow underground station caverns and track crossovers. Clear span openings ranging from70 feet to 100 feet and lengths in excess of 1000 feet, coupled with low rock cover ranging from 25 feet to 40 feet required judicious selection of construction methods, equipment, and proper sequencing of the excavation stages. Rock classifications alone could not predict the behavior of the rock mass during construction. A robust design procedure that considered most of the important aspects of rock behavior and elements of shallow tunnel design, minimized the negative impacts of variable geotechnical data. This paper describes the intricacies of the planning and design of the $16 billion Second Avenue Subway with insight into how to overcome the design complexities and construction challenges of the urban underground.

Jan 1, 2005

By L. F. Ruppert, P. A. Freeman, R. C. Milici, S. J. Tewalt, L. J. Bragg

The U.S. Geological Survey has completed a dig-ital coal resource assessment of six of the top-producing coal beds and coal zones in the northern and central Appalachian Basin coal regions. These include the Pennsylvanian-aged Pittsburgh, Upper Freeport, Lower Kittanning, Fire Clay, Pond Creek, and Pocahontas No. 3 coal beds and coal zones. Resources were calculated on all of the coalbeds/zones, with the exception of the Lower Kittanning coal bed. Preliminary original resources are estimated at about 93 billion short tons (84 billion tonnes), of which about 66 billion short tons (60billion tonnes) remain. Much of the remaining coal in all five coal beds/zones is thinner [<3.5 ft (1.07m)] and deeper [>1,000 ft (305 m)] than the coal that has been mined, but economic resources are still available and mining in each coal bed/zones will continue throughout this decade and into the next given current market conditions.

Jan 1, 2001

By W. Z. Rogers

U.S. feldspar output sold or used in 2004 was estimated to be 790 kt (871,000 st), valued at $43 million free-on-board plant. This was below 2003 and about the same volume as 2002. The strong housing market in the United States maintained demand for ceramic tiles, plumbing fixtures, and fiberglass insulation requiring feldspar and shipments of glass containers increased by about 4 percent. Imports of ceramic tiles and plumbing fixtures continue to increase, taking the place of U.S. produced goods, and the feldspar required to make them. Output included flotation concentrates, feldspar content in feldspar-silica mixtures, potash feldspar and aplite.

Jan 1, 2005

By Albert J. Kritscher

The Similkameen Copper Project located near Princeton, British Columbia, is operated by the Similkameen Mining Company Limited, a wholly-owned subsidiary of Newmont Mining Company. The orebodies for this project are located on both sides of the Similkameen River for which the project is named. The project involves the processing of an average of 15,000 STPD of andesitic ore, mineralized largely with Chalcopyrite, at an overall plant availability rating of 90 percent. Project life is nominally 15 years. Design for the plant and its ancillary facilities was undertaken by Bechtel Corporation with procurement and construction management by Canadian Bechtel Limited. Construction began in June 1970 and first ore was introduced into process in March 1972. This paper concerns itself only with the project tailing system. The processing plant is located on a bench of glacial stream gravels which overlooks the river canyon. This site represented the only relatively flat area of sufficient size to accomodate processing facilities near to the ore- bodies. Reference is made to Figs. 1 and 2 showing the relationship of project features in plan and profile.

Jan 1, 1973

By P. Oghazi

It is possible to have traceability in the mining industry, by parameters and signatures like particle mineralogy, mineral association, texture and mineral liberation. The study is on an apatite-iron ore deposit at Malmberget, Sweden, and characterizes an ore body both mineralogically and texturally in a quantitative manner by using analytical methods like optical microscopy, microprobe (EMPA) and an automatic SEM based system, Particle Texture Analysis (PTA). The mineralogy was evaluated by PTA and characterized by modal mineralogy, mineral liberation and mineral associations. Magnetite has a simple outline and straight grain boundaries and the gangue minerals have a finer particle size with a more complicated texture. The PTA analysis also shows that apatite is associated to magnetite as mixed particles, while smaller grains of magnetite are inclusions in feldspar. Result from particle texture analysis shows that there is a connection which link to the mine-to-mill context, and it may be used to create traceability. This link is not the associations of the main ore mineral magnetite, nor the modal mineralogy. Instead, it is the mineral associations of contaminating minerals (apatite and feldspar) that appear to be most promising since they survive from mine to mill. The modal mineralogy may be used to understand how contaminated minerals break into or out of particles size fraction during grinding.

Jan 1, 2010

By J. A. Marts

Reservoir properties including porosity and permeability distributions in longwall coal mine gobs have direct application to modeling the flow patterns and gas distributions in the gobs. Proper assessment of these distributions is required to assess gob gas hazards such as spontaneous combustion and explosive methane mixtures and to optimize gob gas venthole operation and nitrogen inertization. Determining the reservoir properties is difficult given that the gob is inaccessible and direct measurements cannot be easily taken. Several techniques have been used by previous researchers and will be discussed. This paper will present the methodology used to model the gob compaction by simulating the sequential extraction of coal. Two Western US coal mines were used for case studies. By determining volumetric strain, the porosity and permeability distributions in the gob can be calculated. The geo-mechanical model predicts an axisymmetric volumetric strain distribution with a steeper slope near the start-up room and a shallower slope near the active face.

Feb 23, 2014

By M. S. Celik, G. Onal, S. Atak, A. A. Abramov

An oolitic phosphate ore composed of phosphate (mainly francolite) and carbonates as gangue has been tested for the suitability of the reverse flotation process. The samples were first ground autogeneously followed by the reverse flotation process. While the carbonates were floated by sodium oleate the phosphate was depressed by phosphoric acid. The effect of particle size, reagents type and concentration on flotation recoveries have been investigated to determine the optimum conditions. By this process, a run-of-mine ore containing 16.72 % P205 was upgraded to 28.00% P205 with a recovery of 77.0% The mechanism of optimum flotation with phosphoric acid observed at pH 6.3 is explained based on a relationship involving surface potentials and the ratio of required collector concentrations for the respective minerals.

Jan 1, 1993

By W. C. Shanks

The Pioche District of Lincoln County in southeastern Nevada (Figures 1 and 2) has been an historically important producer of silver, zinc, and lead. Economic geology of districts in the Pioche area is summarized most adequately in recent reports by Tschanz and Pampeyan (1) and Gemmill (2) and only a few major aspects will be discussed here. Production in the Pioche District began in 1869 and early mining concentrated on silver-bearing fissures in lower Cambrian quartzites. In the early 1870&apos;s the Pioche District was second only to the Comstock Lode in world silver production (3). More recent mining activities have centered on the other major ore type in the area, bedded replacement of lower Cambrian carbonates by Ag-Zn-Pb sulfide ore. Production of replacement ore peaked around 1950. The present study is focused on the Pan American Mine because it is an excellent example of low grade carbonate replacement deposits, because there is little structural dismemberment, and because access was readily available. Most previous workers have suggested that both the fissure vein deposits and the bedded replacement deposits of the Pioche districts are a result of spatially related Laramide igneous activity. The purpose of this study is to determine whether ore genesis is a result of igneous activity or if mineralization might be related to late diagenetic processes such as formed Mississippi Valley "type" deposits. Stable isotopes of sulfur, carbon, and oxygen in ore and gangue minerals have been studied to determine the probable isotopic composition of the ore fluid and paleomagnetic studies of the carbonate rocks have been utilized to determine timing of mineralization. Additionally, petrographic and field studies of carbonate lithologies were undertaken in an attempt to delineate non-structural controls on ore localization. These studies are still proceeding and the results presented herein are, therefore, preliminary in nature.

Jan 1, 1979

By R. J. Sweigard

One of the foremost problems in reclaiming prime farmland is compaction of the subsoil which is caused by the reclamation equipment. Wheel tractor-scrapers are most commonly used to replace subsoil and have been blamed for the majority of the compaction problems. Two methods of alleviating this problem that are presently being considered are mechanical subsoil loosening machines and truck- shovel combinations for subsoil handling. A field study was conducted in which dry bulk density measurements were taken in an effort to determine the effectiveness of truck-shovel combinations and subsoil loosening equipment in reducing bulk density in comparison to typical scraper replacement.

Jan 1, 1987

By W. L. Cornell, F. W. Benn

The U.S. Bureau of Mines investigated froth flotation techniques to remove heavy metals (Pb, Cu, and Zn) from southeast Missouri lead mill tailings. It has been estimated that southeast Missouri contains between 200 and 300 million st of Pb tailings stored above ground. The tailings were classified as two distinct types: (1) pre- 1968 tailings from the Old Lead Belt (some more than 100 years old) and (2) post-1968 tailings from the New Lead Belt. The objectives of the investigation were to reduce the Pb remaining in the tailings to (500 ppm (<0.05% Pb) and to attempt to recover a marketable concentrate to offset a portion of the remediation costs. The remaining dolomite-limestone would then be used as mining backfill or agricultural limestone. Bench- scale froth flotation removed, in percent, 95 Pb, 84 Cu, and 54 Zn, leaving 94% of the original weight containing, in parts per million, 400 Pb, 40 Cu, and 300 Zn from the Old Lead Belt tailings. Separate flotation tests also removed, in percent, 85 Pb, 84 Cu, and 80 Zn, leaving 75% of the original weight containing, in parts per million, 400 Pb, 200 Cu, and 500 Zn from the New Lead Belt tailings . Concentrates recovered from the Old Lead Belt were retreated to produce a final Pb concentrate containing 72% Pb with a cleaner flotation recovery of 79%. Froth flotation proved to be a viable method to remove the heavy metals.

Jan 1, 1992

By Dr. George W. Annadale, Dr. Adrian G. Chantler

Materials which are likely to produce Acid Rock Drainage (ARV) can be identified with a reasonable degree of certainty. However, it is not currently possible to predict the concentrations of future contaminant discharges with similar confidence. One way of overcoming this problem is to model the uncertainty in knowledge related to estimates of future contaminant concentrations, and utilize this information in a decision model to decide on acceptable levels of expenditure on ARV control measures. The paper presents a risk modeling approach and proposes a decision model.

Jan 1, 1992