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By Bernie W. Martin, Jesus Schabib

The East Side Access (ESA) Project in New York will be the largest tunneling project ever undertaken by a US railroad. The objective of the ESA project is to connect the Long Island Rail Road (LIRR) Main Line and Port Washington Line in Queens to Grand Central Terminal in Manhattan. The Project is divided into two distinctive segments: Manhattan and Queens. The Queens segment is subdivided into two major components; cut and cover tunnel construction and bored tunnels. The bored tunnels in Queens consist of five tunnels driven from a launch shaft and traverse a railway storage yard, Sunnyside Yard and terminate under the multitrack mainlines of Amtrak and LIRR at portals in the heart of Harold Interlocking where1200 trains pass every day. The soil consists of remnants of glacial till moraines and of outwash and till deposits of inter layered gravel and fines, with the occasional boulders and cobbles and with a high ground water table. It is anticipated that a Pressurized Face Machine, either slurry or Earth Pressure Balance equipped with roller disks to mine the boulders encountered as well as the mixed face, will be used to mine the tunnels. One pass reinforced concrete gasket bolted liner will be used. The cut and cover construction consists of an approximately 21.3 m (70 feet) deep excavation supported by slurry walls and jet grout columns. The slurry walls, in combination with overlapping jet grouted columns, are installed to top of rock forming a closed bathtub to control external groundwater drawdown. Maintaining the groundwater level near its original elevation is of paramount importance in order to prevent undesirable settlements and migration of groundwater that could be contaminated. Mitigation measures to prevent the migration of nearby plums are contemplated for all types of tunneling and excavation work in this site of the ESA project.

Jan 1, 2001

By E. F. Schnitzer, C. Lidstone, D. Cramer, P. J. Wampler

The River Island mining site is located at approximately river mile (RM) 15 on the Clackamas River, a large gravel-bed river in northwest Oregon. During major flooding in February 1996, rapid channel change occurred. The natural process of meander cutoff, slowed for several years by dike construction, was accelerated by erosion into gravel extraction ponds on the inside of a meander bend during the flood. In a matter of hours, the river cut off a meander and began flowing through a series of gravel pits located on the inside of the meander bend. The cutoff resulted in a reduction in reach length of approximately 1,100 m. Erosion by bed lowering, knick point retreat and lateral erosion of upstream river banks occurred quickly. Within two days of the peak flow, 3.5 hectares of land and 105,500 m3 of gravel were eroded from the river bank just above the cutoff location. Much of this gravel moved a short distance downstream into the excavation. Reach slope increased from 0.0022 to approximately 0.0035 in the cutoff reach. Between 1996 and 2003, the knick point from the meander cutoff has migrated 2,290 m upstream, resulting in increased bed load transport, incision, and local lowering of the water table. In 1993, prior to the meander cutoff, transects were surveyed in the River Island reach upstream of the cutoff location. Resurvey of these transects and aerial photo analysis indicates that 96% of the knick point migration occurred during the first winter following meander cutoff. Connection of the flowing river to the off-channel ponds has had minimal effect on water temperatures in the mainstem Clackamas River. It is likely that this minimal change in temperature will decrease as ponds are isolated from active river flow by gravel bar deposition. Fish net-ting in spring 2002, suggests that salmonid use of the pond in the spring is minimal. The most abundant native species netted were large-scale sucker and northern pikeminnow. The most abundant non-native species netted was brown bullhead. Early regulation by state and federal agencies did not adequately evaluate potential impacts to the river and the floodplain; nor did it evaluate future impacts related to geomorphic processes and sediment transport. New permit evaluation methods, currently implemented by both Oregon and Washington, incorporate 1) river dynamism through historic river migration analysis; 2) stability of human structures in light of river dynamics; and 3) sediment transport and its impact on channel stability and dynamics. The gravel pit capture at River Island highlights the potential risks of mining in an active secondary channel of a large gravel-bed river. Mining deeper than the depth of the adjacent channel, within the active migration zone, may increase off-site impacts. In locations where multiple gravel excavations are present within the meander zone, a comprehensive reclamation and restoration plan should be developed which provides long-term channel stability within the natural variability of the entire river reach.

Jan 1, 2006

By Daniel T. Hegyan

The employment of continuous rotary vacuum disc filters to filter refuse from the fine coal washing circuits has been increasing as it has become more important to close the water circuits and eliminate sludge holding ponds. This paper will discuss our past experience filtering refuse, effects of solids concentration in the filter feed, use of polymer flocculation aids, effect of flocculation devices, and effects of particle size and ash content on the filtration rate. Detailed tests were performed on existing installations utilizing coal refuse filters to determine optimum flocculant dosage, solids concentration, and disc rotation speed to form a dischargeable cake. Information was also obtained showing effect of flocculant addition on the moisture of the filter cake. Our test work has shown that the continuous filtration dry cake rates for fine coal refuse correlates very well with the data developed and presented by Silverblatt and Dahlstrom1 except that the curves have moved up the scale by use of polymer flocculant additions. These polymers were not available at that writing. Finally, our tests also confirmed the general premise stated by S. K. Mishra2 that controlled additions of polymer flocculants will reduce filter refuse cake moistures somewhat.

Jan 1, 1974

By Duk-Won Park

The stability problems of back- filled spoil banks became more important since the Federal Surface Mining Control and Reclamation Act of 1977 was enacted. The material properties of spoil banks were categorized as the first part of the study and spoil slope stability was evaluated using computer programs as a second part. Emphasis was placed on the effects of natural barriers, which is required in the federal law.

Jan 1, 1982

By E. Fregeau-Wu

To recycle steelmaking slags for their iron, manganese, and lime contents, removal of the phosphorus-bearing dicalcium silicate and calcium phosphate is essential. Slow-cooling of slags was necessary to promote the sufficient grain growth to achieve liberation. In-situ grain size distribution determination showed that a high soaking temperature, a long soaking time, a very slow cooling rate, and the addition of fluorspar were shown to promote grain growth. High gradient magnetic separation on slow-cooled slags removed much of the dicalcium silicate. Liberation modelling was used to discuss the breakage and beneficiation characteristics of the slow-cooled slags.

Jan 1, 1992

By I. Meliadis

This study presents the methodology and proposals for the restoration of an abandoned quarry in the Greek island of Milos. The local data (soil, vegetation etc.) of the island were collected, analysed and compiled into thematic maps using Geographical Information Systems. The restoration plan was based on the G.I.S. database and suggested the revegetation of the disturbed lands with herbaceous (grasses and legumes) or woody (shrubs and trees) plants. Plants should be indigenous or from other areas with the same vegetation type. Herbaceous plants establish and grow easily protecting the soil from surface erosion. The revegetation success depends on the seed quality, planting season and methods as well as local environmental conditions. Our proposals aim to restore the abandoned quarry with methods that follow the natural succession of vegetation, have minimal environmental impact, low cost and the expected result will be similar to the surrounding undisturbed land.

Jan 1, 2002

By Biao Qiu

Longwall and/or room-and-pillar mining operations in multiple coal seams could not only induce subsurface and surface subsidence but also cause interactions between these mined coal seams. The interaction might destabilize mine structures and subsequently induce additional strata movements. Mechanical models to utilize the predicted subsurface deformations to assess the interactions and the consequences have been developed. The models are incorporated into a computer program, CISPM-MS, for predicting the final surface movements and deformations as well as the mining interactions associated with multi-seam coal mining operations. It predicts final surface movements and deformations caused by the individual mining operations and by the interactive effects. The program can also be used to assess mine structural stability in multi-seam mining operations. The paper presents the developed interaction models and their application in surface subsidence prediction caused by multi-seam mining operations. A case study involving mining in two coal seams, using longwall and room-and-pillar mining methods, respectively, will be used to validate the program.

Jan 1, 2013

By Y. Yu

Florida phosphates ore typically processed by reverse flotation with an intermediate acid-scrubbing step. A single-reagent flotation process, using fatty acids or amines as the collector, would eliminate the intermediate scrubbing step plus an additional flotation step. This would not only simplify the process flowsheet but would also result in reduced reagent costs. The potential of single-reagent flotation of Florida phosphates using fatty acids as the collector is examined in this study. Introduction The beneficiation scheme now used for Florida phosphates involves the following three steps (Smith, 1976: Lawyer et al.. 1978, 1984: Moudgil et al, 1976, 1979, 1986, 1987): •rougher flotation of fluorapatitc particles using a fatty acid-fuel oil mixture as the collector. •scrubbing of fatty acid, and •cleaner flotation of silica particles using amine collector. Several attempts have been made to simplify the process flowsheet by floating either apatite or silica (not both, as is the current practice). However, single-reagent flotation schemes have had limitations in meting the concentrate-grade requirements of the phosphoric acid plants. In this study, an attempt was made to use a minimal amount of the fatty acid-fuel oil collector to obtain an acceptable grade (rougher) concentrate. Invariably, the recovery in such cases is expected to be lower than in the conventional rougher-flotation step. Therefore, scavenger flotation of tailings with additional fatty-acid collector was conducted to improve the phosphate recoveries.

Jan 1, 1997

By H. Bradley Johnson

A number of Federal laws affecting safety and health in the mining industry has been enacted and revised over a period of many years. We have tended to classify these laws and their applicability into three categories: 1) coal mines, 2) metal and nonmetallic mines, and 3) mines with Federal supply contracts. With the growing attention which is being given to mine safety by the Federal government, the entire mining industry should keep aware of all developments in the administration of each of these laws.

Jan 1, 1970

By S. R. Stine

The Cyprus Thompson Creek Mine is located at 2,286m (7500 feet) elevation in the Central Idaho mountains, 61.16 kilometers (38 miles) southwest of Challis, Idaho off State Highway 75. The Thompson Creek molybdenum deposit lies near the eastern border of the late Cretaceous Idaho Batholith within a complexly deformed sequence of Paleozoic sedimentary rocks. Molybdenum mineralization is contained in a composite biotite granodiorite-quartz monzonite stock considered to be genetically related to the Idaho Batholith intrusive event. The ore is being mined by open pit methods and delivered to the concentrator stockpile with an overland conveyor belt system. The concentrator is designed as a 22,680 metric tons (25,000 ton) per day plant at an average head grade of 0.1% Molybdenum.

Jan 1, 1986

By J. V. Bymark

It is the intent of this paper to discuss the autogenous grinding circuit at Hibbing Taconite. The scope of the presentation includes; a brief history, the process flowsheet and the steps taken to improve mill productivity, availability and metallurgical performance. Hibbing Taconite is located near the center of the Mesabi Range in Northern Minnesota 100 miles from the Canadian border and 80 miles north of the Lake Superior Port Cities of Duluth and Superior. A 105 mile railroad connects us with the port of Superior, Wisconsin, where our pellets are loaded into lake carriers for lower lake destinations. It is worthy to mention the Mesabi Range's most famous landmark which is immediately to the south of our mine area. This is the Hull Rust Mahoning Mine which operated until the mid-1970's producing more than 700 million tons of red ore between 1893 and 1973.

Jan 1, 1985

By R. W. M. Lai

In flotation or hydrometallurgical leaching of minerals, the cumulative metals recovery for a given process condition generally approaches a maximum value or an asymptote as the process time increases. This paper discusses the experimental methods of identifying and obtaining the asymptote of metals recovery through kinetic studies. In flotation, the kinetic asymptote of metal recovery, or ultimate recovery, is a function of grinding and collector dosage, but within a realistic variable range, is not a function of pH or temperature. However, variations in grinding, collector dosage, pH and temperature, all exert noticeable effects on flotation kinetics. Frothers generally have a minor affect on the asymptote, but have a major affect on flotation kinetics. The asymptote from batch flotation is found to be identical to that of a continuous flotation. In hydrometallurgical Leaching, the asymptote of metal recovery for a given leaching system is a function of such variables as temperature, particle size, and acid concentration.

Jan 1, 1983

By D. Y. Geng

Longwall mining is a relatively new mining method in the United States. Early trials in the eastern and central coal fields were not successful, mainly because, among others, the face supports did not have sufficient capacity. It was not until in the late 1960's, when the high- capacity self-advancing powered supports became available, that longwall mining was successfully reintroduced. Since then the number of mines employing the longwall method has been steadily increasing. It has reached approximately 7.5% in 1981. Currently longwall mining is used mainly in the Appalachian coal field. The seam depth ranges from 150 to 2500 ft. but mostly between 300 and 1400 ft. The seam thickness ranges from 32 to 144 inches with the majority between 40 and 100 inches. Nearly all longwall mining are in flat or nearly flat seams extracting in single slice, although one inclined and one thick seam longwall mining have been either operated or initiated in Colorado.

Jan 1, 1983

By Jackson G. Jenkins

Magma Copper Company's San Manuel SX-EW facility has operated since May, 1986. The original facility had a design capacity of 25,000 tons per year of electrowon copper cathode produced by processing pregnant leach solution from an open pit/heap leach operation. In 1988, the plant was expanded to 50,000 tons per year to incorporate processing in-situ leach solutions. This paper focuses primarily on the heap leaching area with regard to exploration, testing, feasibility, permitting, design and construction, and operating practices. Research utilizing surfactant leaching aids to enhance copper recovery is also discussed.

Jan 1, 1993

By J. L. Watson

n the U.S., lead has been produced via blast furnace processing for over a century, and the slags from that pyro-metallurgical process have been accumulating on industrial sites over that extended period. Lead blast furnace slags typically contain both lead and zinc compounds in an iron-silicate matrix, and it appears highly likely that such materials will have to be processed in the near future to meet with EPA regulations. Thus it is appropriate to investigate possible processing routes to render the slags non-hazardous and simultaneously to recover metal values to partially off-set the inherent high cost of processing such materials. There are two major processing alternatives: one being pyrometallurgical and the other hydrometallurgical. The research reported here investigates leaching/solution purification/recovery processes for lead and presents experimental data for the treatment of lead blast furnace slags from S.E. Missouri. The results of the research suggest that both lead and zinc can be removed effectively from the slag, and that metallic lead can be recovered directly from the organic extractant utilized for solution purification.

Jan 1, 1995

The purpose of this paper is to demonstrate how the Computational Fluid Dynamics (CFD) technique can be an attractive approach to evaluate the performance of face ventilation systems. To present the capability of the CFD for such a study and for design purposes, a series of simulations using CFD have been performed at the Department of Mining Engineering, University of Kentucky, for different face ventilation arrangements (e.g. different scrubber geometries, brattice (curtain) and continuous miners locations, airflow quantities, etc.). Results from these simulations are displayed as three dimensional graphs and discussed. Needs for the field validation of these results and refinements of design methodologies are also discussed.

Jan 1, 1998

By Elisabeth Tønnesen, Lloyd Tunbridge

"SUMMARY Injection grouting in rock around tunnels is used to reduce or stop water inflow. Little is known about the distribution of pressure within the rock mass during and after grouting. Instrumentation was developed to record pressure at the back of the packers inside the rock mass during injection grouting in order to improve our understanding of the process. Using this equipment measurements inside multiple injection holes during injection pumping have been made during several rounds of injection grouting in a tunnel. The data has been compared to the data recorded on the grout pumping rig and analysed to gain an understanding of the behaviour of grout injection process in the rock mass. The initial results are reported in this paper. INTRODUCTION Construction of a tunnel in soil or rock below the ground water table frequently results in the flow of ground water into the tunnel if the ground is permeable or fractures conductive. The injection of cement or chemical based grouts is frequently used during tunnel construction to reduce flow of water into a tunnel. Significant water flow into a tunnel is undesirable for several reasons: • there is a high cost in pumping out water over the lifetime of a tunnel; • drips and flows of water have to be diverted from the roadway or track; • where freezing conditions occur there is the possibility of ice build up and; • ground water levels may be changed possibly affecting surface water such as causing drainage of lakes and ponds, and changes in vegetation. Grout injection is most effectively done ahead of excavation to ensure that the grout penetrates the ground. Where heavy flows of water already occur into a tunnel the grout may be washed out before it sets. Normal practice in ground where water flows are encountered is to inject grout in a number of long holes ahead of the face with outer holes forming a ring around the proposed tunnel excavation – eventually forming a shield of grouted rock around the final tunnel, Figure 1. The holes may be sealed off a couple of metres into the rock with an expandable rubber plug around a pipe through which the grout can be injected, Figure 2. A one-way valve in the plug stops the grout from flowing back out of the hole when pumping stops and avoids grout flowing out through neighbouring holes. The rubber packer with a one-way valve permanently installed in the injection hole precludes the measurement of pressure down the hole when pumping is stopped."

Jan 1, 2016

By E. L. McHugh

Digital camera and computer technologies can be used to monitor mine slopes and provide real-time warning of rock falls. NIOSH researchers assembled a surveillance system using low-cost video cameras and computer software from the security industry to test its effectiveness. The system is designed to signal an alarm when motion is detected and to record images of the scene. Masking can restrict motion detection to specific areas within the camera view; sensitivity is adjustable. The time-stamped images provide a record that can help reconstruct and quantify an event. Video motion detection can augment standard monitoring methods to increase safety in surface mines.

Jan 1, 2004

By D. E. Larson

The U.S. Bureau of Mines has developed a image analysis methodology to correlate the energy consumed during the grinding of an ore to the mineral liberation achieved. Energy consumption values are obtained using a laboratory-scale ball mill equipped with a torque sensor, and an automated image analyzer is used to determine the liberation present in ground products. By combining liberation information with energy consumption data an appraisal can be made of the energy required to liberate the mineral(s) of interest. Results of tests performed on a complex sulfide material determined the effects of grind duration on the liberation achieved and the energy efficiency.

Jan 1, 1995

By S. A. Allison, N. P. Finkelstein

After a brief consideration of the properties of zinc sulfide minerals, their flotation characteristics, and their reactions with thiol collectors, the literature on the activation of the minerals by cupric ion, their deactivation by cyanide, and their depression is reviewed in detail. The distinction between deactivation and depression is stressed. The contradictions in the published results and theories are discussed and attempts are made to resolve them. It is concluded that, whereas all aspects of the subject require further investigation, the study of depression is most likely to yield benefits in practice.

Jan 1, 1976