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By G. Zhu

Bulk and differential laboratory flotation tests have been carried out using a synthetic mixture of chalcopyrite and molybdenum ore. In addition to boiling and roasting, six different depressants are tested so that the best conditions of separation can be identified. These reagents include sodium cyanide with and without zinc sulfate, potassium ferrocyanide, sodium hydrosulfide, arsenic Noke's reagent, and sodium sulfide. The data indicate that most of these reagents are effective chalcopyrite depressants. However, sodium hydrosul fide can be used preferably if economic, operational, and environmental factors are taken into consideration.

Jan 1, 1983

By H. Mischo, R. Ellmies

Uranium has been mined in Namibia since the 1970s. The worldwide increasing need for energy in the early 2000s has led to the development and opening of a second uranium mine in 2007 and has triggered an increased interest in uranium exploration, often referred to as “the Namibian Uranium Rush.” In all, four mining licenses have been granted by the Namibian Government, which currently has two mines in operation, a third undertaking trial mining and the fourth in project finance negotiations. In addition, highly intensive prospecting activities at additional deposits are at an advanced stage. The finalization of the strategic environmental impact assessment (SEA) on uranium mining in 2010, the first of its kind and scale in the world, has enabled the Namibian government to assess this uranium rush and its tremendous legal, socioeconomic and environmental impacts and to prepare for the different future scenarios conceivable when this article was written in 2011, including both a skyrocketing and a complete breakdown of demand scenario. The Fukushima disaster and plans of the Namibian government to significantly increase royalties and company taxes in 2011 have threatened the market situation, forcing investors to reevaluate Namibian uranium mining projects. However, with the tax and royalty increase initiative since withdrawn, most projects are back on track at this point in time.

Jan 1, 2012

By J. L. Huiatt

Kerosine, fuel oil No. 2, vapor oil, and fuel oil No. 6 were separated into general hydrocarbon fractions by ion exchange chromatography and adsorption chromatography. The collecting properties of these fractions were evaluated by flotation of molybdenum and copper minerals from a natural chalcopyrite ore. Paraffin fractions and aromatic fractions of low polarity produced the best molybdenum recoveries. Selective flotation of molybdenite from copper sulfide minerals was not possible with any of the chromatographic fractions.

Jan 1, 1972

By T. Hall, R. Ferris

Waterjets and diamond wire saws have raised the productivity and lowered the cost in dimensional granite quarries. While the cost of diamond wire sawing is substantially lower than waterjet, the judicial use of the waterjet can simplify and improve the overall operating efficiency and predictability. Granite is the hardest commercial stone and only the gem-stones garnet and diamonds are harder. The introduction of industrial diamonds has made it possible to quarry and process granite at costs equal to or less than other natural stones – making granite, with its superior properties, the best value available.

Jan 1, 2004

By Yao Yevenyo Ziggah, Victor Amoako Temeng, Solomon Evans Kweku Koomson

Tyre hours/life deficit is a major operational challenge facing the mining industry which adversely affects materials production and costs. An accurate forecast of the tyre life is key in addressing this menace. This study for the first time employed the hybrid intelligent technique by utilising three metaheuristic optimisation algorithms, including particle swarm optimisation (PSO), genetic algorithm (GA), and whale optimisation algorithm (WOA), as trainers for the parametric weights and biases to optimise multilayer perceptron neural network (MLPNN) for enhancing prediction of on-site dump truck tyre life in the mine. Four hybrid models known as PSO-MLPNN, WOA-MLPNN, GA-MLPNN, and BP-MLPNN were developed using a total of 157 tyre dataset records obtained from a surface mine in Ghana. In assessing the prediction performances for the models developed, five statistical performance metrics of variance accounted for (VAF), Nash–Sutcliffe efficiency index (NASH), coefficient of determination (r2), mean absolute percentage error (MAPE), and correlation coefficient (r) were utilised. Moreover, ranking, uncertainty analysis and Bayesian information criterion (BIC) techniques were utilised to establish the most effective hybrid model, whereas sensitivity analysis was conducted on the input parameters. Results achieved showed that PSO-MLPNN was the best for prediction because it had the least MAPE value of 1.196% and relatively high values of VAF (99.642%), NASH (0.996), r2 (0.996), and r (0.998). Besides, PSO-MLPNN had the best selection criteria values of 6, 7.1725, and 444.834 for the ranking, uncertainty analysis and BIC respectively. Hence, PSO-MLPNN is recommended for the prediction of on-site dump truck tyre life for the studied mine.

Mar 11, 2024

By Stanisław Prusek, CHONG WEI, Huawei Xu, Jun Wang, Andrzej Walentek, Artur Dyczko, Derek B. Apel

The excavation-induced stresses transferred from the panels or pillars in upper coal seams play a key role in the occurrence of rockbursts in driving roadways during close-distance coal seam mining, which has become a common problem and threat to many underground mines. The authors established a 3D finite-difference numerical model via FLAC3D software using the closedistance coal seam mining conditions in the Zofiówka Mine as a case example to reveal the rockburst mechanism in such conditions. The excavation-induced vertical stresses are analyzed, which provides a basis to build a conceptual model to explain the possible source mechanism of the rockburst under such conditions. Nine typical rockburst indicators considering different contributing factors are then selected as the evaluation criteria to assess rockburst potential in the study site. The results suggest that the superposition of multiple excavation-induced stresses of the main drift and tailgate provides an environment for stress concentration and energy accumulation. The side abutment stress induced by mining in the upper coal seam has a “strengthening” effect to the rockburst occurrence. The great deviatoric stress induced by complex excavating situations is another important exterior cause. A strict calibration procedure should be implemented before using indicators to predict rockburst potential. A methodology was proposed to estimate the location and magnitude of rockbursts combined with numerical modeling, laboratory tests, and feedbacks from the field. The study could provide some references and guidelines for preventing and mitigating rockbursts in underground mines under similar engineering conditions.

Aug 26, 2021

By C. R. Tinsley

Valuations can be molded, twisted and misinterpreted. Cases of spurious scope setting; limits to the information or access by the valuer; difficulties with the lack of comparative valuations; inappropriate valuation methods and outright speculations are described. None should be accepted by an experienced, independent minerals valuer. The Australasian Institute of Mining and Metallurgy (TheAusIMM) is working on a Valmin Code for which a Manual of Best Practice and Valuation Guidelines may be developed.

Jan 1, 1995

By Christian Maguire

Tunnel contracts in New York have in recent years had few bidders with the bids received being much higher than anticipated. Since 9/11, security has become a key issue in planning key infrastructure projects in New York. This is especially true in the case of large water supply tunnels. Striking the right balance between cost and security was the major factor in determining the best configurationfor the Kensico-City Tunnel. This paper outlines the efforts made to determine realistic probable bid costs for the tunnel contracts, and the innovative approaches taken to deal with security issues.

By Casters B. Foster

The U.S. Department of Energy has undertaken, in a cost sharing partnership with industry and utilities, an extensive coal-oil mixture (COM) combustion program in a number of promising applications. One of these is the injection of COM through tuyeres into a blast furnace in lieu of oil. From work done previously, it has been established that COM can be burned in existing oil, fired facilities. The issues being addressed by the current DOE program are: 1) determination of best available technology to achieve environmentally acceptable operation, and 2) determination of applications for which COM can be utilized economically.

Jan 1, 1978

By Wern-ping (Nick) Chen

The Florida Department of Transportation District 6 (FDOT D6) began a study in 1987 for a master plan to improve the traffic circulation and congestions between the Port of Miami (POM) and downtown Miami, FL. This study included a tunnel connection between two man-made islands, the Watson and the Dodge islands. Though a finding of no significant impact (FONSI) was completed in 1992, the project remained on hold for about 10 years. In 2002, Florida Turnpike took over this project, re-evaluated its benefits to the lo-cal communities, determined its feasibility (specifically the tunnel options) and established a probable cost. In 2005, the FDOT D6 regained its charge over the project and concluded that a bored tunnel under Biscayne Bay is feasible. Its primary components are: ? Widening of the MacArthur Causeway Bridge, to accommodate truck traffic to the Port of Miami. ? A tunnel connection between Watson Island and Dodge Island, where the POM is located. ? Connections to the POM roadway system, either for the traffic from the city of Miami or for the truck traffic from I-395 to the POM. The project will improve access to and from the POM and provide a dedicated roadway connector linking the POM with the MacArthur Causeway (State Route 41/1) and I-395, specifically for the trucks in and out of the POM without going through downtown Miami. As identified in the project information memorandum (PIM), its primary objectives are to: ? Improve access to the POM, helping to keep it competitive and ensuring its ability to handle projected growth in its cruise and cargo operations. [ ] ? Improve traffic safety in downtown Miami by removing POM traffic, trucks and buses from the congested downtown street network and, in doing so, facilitate ongoing and future development plans in and around downtown Miami.

Jan 1, 2009

By D. P. Bryan

The identification and-develop¬ment of new construction aggregate resources, the most common mineral mined, is an essential need in this country's growing urban areas. In developing an aggregate exploration program, a thorough geological identification of all potential aggregate resources in an area is still of primary importance but other factors have also to be considered. These include physical properties, end product application, transportation and mining costs, and local government regulations including zoning. The present major aggregate producers are most likely to develop these future resources and are in the best position to initiate comprehensive exploration programs.

Jan 1, 1987

By Timothy P. Smirnoff

Sustaining the region?s mobility needs, achieving projected economic growth, and maintain Midtown Manhattan as a center of regional, national and global importance has led to continued investment in commuter rail and transit infrastructure in New York City and resulted in design and construction of large underground caverns. The current plans for stations in Manhattan include New York Penn Station Expansion (NYPSE) caverns for Trans Hudson Express (THE) Tunnel Project for New Jersey Transit (NJ Transit) and the Port Authority of New York and New Jersey (PANYNJ), Metropolitan Transportation Authority Capital Construction Long Island Railroad (MTACC/LIRR) twin caverns for East Side Access (ESA) Project, and station caverns of the No. 7 Line Subway Extension Project and Second Avenue Subway Project for Metropolitan Transportation Authority Capital Construction/New York City Transit (MTACC/NYCT). This paper provides a general overview of these large caverns now in design or construction in Manhattan, the area?s geologic setting, the geotechnical factors considered and approaches commonly applied for cavern design.

By A. J. Thompson

The Metropolitan Transportation Authority (MTA) East Side Access project (ESA) will, when it is complete, provide a new link to the east side of Manhattan from Long Island, NY that, linked with the Second Ave. Subway currently under construction, will assist in relieving overcrowding at Penn Station as well as the Lexington Ave. subway. ESA will bring Long Island Railroad (LIRR) directly from Long Island into a new station located 37 m (120 ft) beneath the existing Grand Central Terminal (GCT) located in the heart of Manhattan. It will connect the LIRR?s mainline tracks in Queens, via the existing 63rd Street Tunnel under the East River, to a new terminal constructed within, and beneath, the historic Grand Central Terminal.

Jan 1, 2012

By Donna L. Boreck

In an effort to increase recovery in thick and closely spaced coal seams, the Bureau of Hines, U.S. Department of the Interior, is studying the feasibility of introducing three mining methods-high-face longwall, multi-slice longwall, and longwall caving-in western coal operations. Geology plays a significant role in determining the success of such methods. Some of the factors that will affect development are as follows: (1) thickness and three-dimensional configuration of the seam, (2) cleats, joints, and fractures in the coal and roof rock, (3) roof composition and variability, and (4) coal quality and changes in quality within the seam. Through geologic mapping, the presence of many of these factors is predictable prior to development.

Jan 1, 1987

By R. P. Schneider

The Chino mine, concentrator, and smelter are located in Grant County in Southwestern New Mexico. Chino Mines Company is a partnership two-thirds owned and operated by Kennecott Santa Fe Corp., and one-third owned by MC Minerals Corp. (Mitsubishi) of Japan. The Chino Ore Body The Chino ore body is a widely varied deposit of rock types and contains intrusive stocks and sediments. The stocks contain chalcocite in a matrix of quartz, mica, and feldspar. Much of the feldspar is altered to clay. Some of these stocks are enriched with native copper. The sediments contain chalcopyrite associated with gangue minerals including magnetite, pyrite, garnet chlorite, and epidote. The contact of the stock and sediment is heavily altered to chlorite and clay. The stock ores contain economic quantities of molybdenite. The operating work index of Chino ore varies from 5 to 20 kwh/ton and averages 8.5 kwh/ton. The ore head to the concentrator averaged 0.81% copper and 0.010% molybdenum. Fifteen percent of the total copper head exists as nonsulfide mineralization.

Jan 1, 1985

By W. G. Prast

Investments in fuel minerals and non-fuel minerals by petroleum companies are not a new phenomena. During the past 25 years, oil firms have entered mining via the acquisition route as well as by the direct development of grassroots mines. In the early 1980s, the "merger mania" in the natural resource industries came to a head. Oil company takeovers of mining firms, as well as other mergers between oil producers, captured headlines repeatedly, and speculation ran wild as to who would next acquire whom. Table 1 summarizes leading mining company mergers in the past two decades. There are some special features to the latest round of minerals investments undertaken by oil companies. First, direct takeovers of mining companies have become the preferred means of entry into minerals, with entry from scratch being relegated to the sidelines. This was not always the case. While there are instances of oil firms buying coal and copper companies dating back to the 1950s and 1960s, most of the early minerals work by petroleum firms was from internally generated projects. When the oil companies first became involved in uranium, for example, the uranium mining industry was in its infancy. There was not much market structure to buy, and it was relatively easy for everyone to get into uranium on the ground floor.

Jan 1, 1983

By W. M. Luff

The Brunswick No. 12 Deposit is a large polymetallic massive sulphide deposit, occurring in Ordovician age rocks of the Tetagouche Group. Silver is contained within the sulphide zones and economically it is the second most important commodity produced. Brunswick is one of the largest silver producers in Canada. The distribution of silver within the mine is presented, with examples from various levels. The concentration of silver can be shown to be related to both stratigraphy and structure. The mineralogy of silver in mill products is also presented.

Jan 1, 1986

By M. Sengupta

Surface mining in arctic regions is characterized by many unique problems. Continuous and discontinuous permafrost (perennially frozen ground) occurs in most of the arctic and subarctic areas. Permafrost presents special problems of slope stability. Stability of permafrost depends on its temperature, moisture content and material type. Permafrost slope fails due to solifluction, disturbance of ice rich slopes, and liquefaction. Drilling and blasting of frozen ground present special problems. Depending on their degree of saturation with water, freezing soils and rocks have a number of important characteristics that affect blasting efficiency. Metals used in mining equipment and mining structures require special selection. At low temperatures many steels lose most of their normal ductility and toughness (resistance to brittle fracture). The paper discusses engineering solutions to unique problems of arctic mining.

Jan 1, 1986

By P. W. Hunter

The construction of a major sewerage scheme requiring 15.3 km of 5.5m excavated diameter tunnel in basalt, mixed and soft ground has been undertaken by the Melbourne and Metropolitan Board of Works. A double shielded Tunnel Boring Machine was selected to excavate 13.7 km of basalt and mixed ground. Advanced methods for recording operational data on the TBM were introduced. Progress to date has shown that the TBM can excavate rock very effectively with a best weekly production of 178.8m; soft ground has been encountered and successfully handled.

Jan 1, 1987

By Mark Rybak

On Aug. 31, 2006, Tropical Storm Ernesto hit the city of Richmond, VA. The Battery Park area was hit particularly hard, as flooding forced an evacuation of the area. A large sinkhole collapsed a sewer line in the Battery Park area, blocking the pipe and causing more serious flooding. This article describes the fast track design, bidding and construction of an emergency tunnel to bypass the collapsed sewer. Innovative value engineering, tunneling and shaft-sinking methods and final lining design all contributed to the success of this project. The storm inundated Richmond, VA with up to 305 mm (12 in.) of rain that, in some areas, caused widespread flooding and damage. One of the hardest hit areas of Richmond was Battery Park. A major trunk sewer in the Battery Park area collapsed and caused local combined sewer and stormwater flooding. The collapsed sewer was a 2.4-m x 76-mm (8-ft- x 3-in.-) wide by 2.7-m- x 152-mm- (9-ft- x 6 in.-) high arch sewer that was constructed in the 1920s and later filled over with municipal solid waste and a soil fill cap to cur-rent elevations. A sinkhole was created in the area of collapse approximately 18 m (60 ft ) deep and 31 m (100 ft) in diameter. This caused the existing arch sewer to become blocked. As a result of this blockage, contaminated floodwaters reached depths in low-lying areas in excess of 8 m (25 ft).

Jan 1, 2008