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By J. Snowberger III

Rhenium is a valuable and extremely rare chemical element with unique chemical properties. It is extracted commercially as a byproduct from the processing of molybdenite associated with porphyry copper ores. There is a present interest in recovering rhenium from copper pregnant leach solutions (PLS) produced by copper heap and stockpile leaching. These solutions contain rhenium at very dilute concentrations, typically in the 1 mg/L concentration range. This paper describes laboratory column ion exchange experiments to extract rhenium from these solutions using weakly basic anion exchange resins and actual plant PLS from two operating mines. The dynamic loading and elution behavior of Re on Purolite® A170 and A172 is discussed.

Feb 23, 2014

By Thomas E. Shufflebarger

Glass is one of man's most versatile creations. ---The earliest glaze known---is about 12,000 B.C. ---The oldest pure glass is a moulded amulet of about 7,000 B.C.---. Indicative of a knowledge of properly-proportioned, quality raw-material, means were found for producing the first relatively clear, transparent glass at about the beginning of the Christian era. The fundamentals of almost all the modern, technical processes of manufacture were established during the 3rd Century. (1) Glassmaking, practiced in Colonial America, was moved toward the Ohio Valley in response to increasing demands for fuel. This move, beginning in the 1860's resulted in the use of the glass sands contained in the Oriskany (and St. Peter) sandstone. (2) Glass sand,(3) virtually pure, fine-to-medium-grained quartz sand(4) is the principal raw material used in the manufacture of glass; it constitutes proportions which range to a maximum of about 72% and seldom is glass made without it. However, acceptable glass sands are, invariably, those which most nearly fit the glass-producer's economic needs and any method used to evaluate a raw material's potential must finally prove equatable with such needs. As used in the United States, source-rocks of glass sand include sandstone, unconsolidated silica sands, quartzites and vein-quartz. Admixtures of silica sand and other (principally clay and feldspar), readily separable components have been proven viable. However, the silica sand, refined by nature to a high degree of purity, is the desirable product of exploration. If the term, standard, is justified by long-continued use, the Oriskany - and St. Peter sandstones are, together, the nonesuch of the glass sand industry they provide the principal tonnage of melting sand. According to Grimsley,(5) Ottawa, Illinois, glass-sand is considered the standard glass-sand of the West and the analyses of Berkeley Springs sand (Oriskany) compare most favorably with this sand.

Jan 1, 1974

By Richard L. Ash

Usually stresses generated by explosive charges during blasting are considered to propagate through materials in a spherical manner. Although conical stress-waves had been suggested by a few investigators they have never been clearly defined or critically observed. An experimental technique using models and lengths of Mild Detonating Fuse was developed to produce conical stress-waves and study their effects. Several materials with different properties were tested to compare the influence of those properties on wave shape and crater formation. The investigations showed that whenever column charges were end-initiated, conical stress-forms were produced if the explosive's velocity exceeded the energy propagation velocity of the surrounding material. The stress-cone angle significantly affected fragment size and shape as well as the geometry of craters produced.

Jan 1, 1967

By Charles H. McGuirk

The movement of iron ore, limestone and-coal on the great lakes involves an intricate transportation network between mine, dock, vessel, railroad and consumer. The system requires that stockpiling be performed at certain points in the pipeline because of the seasonal closing of the lakes, traditionally, this has been accomplished at origin and destination with a substantial cost. Impact to both the shipper and consumer, From the time that the raw material is removed from the ground, expeditious handling and movement to final destination is threatened by a series of potential delays. An initial movement from mine or processing plant to the upper lake port must be coordinated between rail equipment and dock facility, As each vessel is loaded, a schedule must be developed which routes the cargo to an unoccupied lower lake port. However, if the vessel is not delayed by unpredictable weather conditions on the lake, the boat may still arrive at a port congested with other vessels awaiting their turn to unload.

Jan 1, 1973

By S. H. Amini, A. Noble

"While many classic mineral processing circuit design approaches rely on deterministic methods, numerous studies have shown that the uncertainty inherent to the various input parameters can significantly influence design decisions. In a separation circuit, many of the technical uncertainties can be mathematically represented as statistical distributions for the unit recovery and feed grade. These uncertainties are then propagated by the circuit design and reflected in the circuit performance indicators, such as product grade and global recovery. An effective design strategy entails identifying which units are most influential in this uncertainty propagation and thus merit further consideration. Unfortunately, few analytical tools provide this information, particularly those that rely solely on deterministic methods. However, one promising approach is through the application of Taguchi’s method, in a fashion similar to statistical tolerancing of manufactured products. Since the technical challenges are fundamentally similar, Taguchi’s method shows promise in evaluating the level of compounded uncertainty by various circuit designs while determining the role of each separation stage on the overall selectivity and variability of separation circuits. This paper demonstrates Taguchi’s method in several two and three unit circuit designs. INTRODUCTION AND METHOD DESCRIPTION Uncertainty in Mineral Processing Circuit Design Analysis and estimation of uncertainty propagation in mineral processing separation circuits is an essential and significant aspect of an optimal circuit design procedure. Most of the current circuit design methodologies have been constructed, implemented, and validated using a deterministic modeling approach. However, numerous studies have shown that the inherent uncertainty induced by uncertain design parameters can be a significant factor in many mineral processing applications (e.g. Kraslawski 1989; Xiao and Vien 2003; Ghaffari et al. 2012). Thus, an effective circuit design methodology must be able to quantify uncertainty in separation circuits with limited input data. This paper describes Taguchi’s method, as an experimental design technique, to approximate uncertainty in mineral processing applications, and then the similarity of results between Taguchi’s method and Monte Carlo Simulation is investigated. Monte Carlo Simulation The term “Monte Carlo Simulation” has been used to refer to a variety of stochastic simulation methods spanning a broad array of business, technical, and scientific domains. Most generally, Monte Carlo Simulation refers to numerical analysis which is based on (pseudo) random sampling from a domain of input parameters with a known statistical distribution. This methodology allows one to determine the distribution of expected results from a standard deterministic process model. Execution of a Monte Carlo simulation begins by identifying the domain of input parameters, statistical distributions for each parameter, and a deterministic process model which describes the anticipated result as a function of the inputs. Next, one discrete random sample is taken for each input parameter, considering the input distributions. The process model is then solved for this mix of input parameters, producing a single simulation result. This procedure is then repeated a “large” number of times, utilizing new randomly sampled input parameters for each simulation iteration. Once the desired number of iterations is reached, the results of each independent simulation are aggregated to produce descriptive statistics such as minimum, maximum, mean, standard deviation, kurtosis, and other distribution parameters. Given enough iterations, the Monte Carlo method fully explores potential synergies between the input parameters. The methodology does not require the process model to be differentiable, continuous, or even analytically defined. While the number of required iterations varies in relation to th"

Jan 1, 2017

By C. Haycocks

The evolution of longwall mining is briefly traced from its inception in England in the 1620's. In the beginning this method recovered 90% of coal with roof closure controlled by packs and walls. Mechanization began with kerf cutting, crude face conveyors, and improved face support. Full face mining was accompanied by the introduction of self-advancing hydraulic supports. U.S. longwalls evolved a retreating system to recover blocks of coal outlined by room and pillar panels. Computer control combined with the most modern technology has greatly increased productivity. Past trends are used to predict future technological directions.

Jan 1, 1997

By R. Froidevaux

Geostatistical estimation techniques were customized to enable forecast of production figures at the Silver Bell uranium mine (Uravan District). Surface drill hole data were used to provide a block model of kriged estimators of average uranium grades. The recoverable figures, such as ore-waste ratio and ore grade, are then deduced from regressive curves previously obtained from underground information and production data. Cross-validations of the entire model were performed and were found positive.

Jan 1, 1981

By C. D. Broadbent

Open pit blasting can be a low cost routine or a high cost bottleneck depending on geology, environment and the operator's ability to master site conditions. Because blasting is a repetitive operation, there should be ample opportunity to optimize the process; but ordinarily this optimization is rarely achieved and then only if conditions remain consistent and predictable. Often, however, and particularly with porphyry coppers, hidden differences in rock characteristics nullify the operator's best efforts. At a porphyry copper deposit being mined by Kennecott Copper Corporation, there are all of the following rock types: oxidized and fresh porphyry, altered and silicified limestone, explosion breccia, rhyolite, sandstone, shale and several others. The units can cover large areas or be limited to a few tens of feet in maximum dimension. They are rarely visible on the bench surface and often do not show up in the bench slope. Even though the blastability of these rocks varies substantially, a generally-uniform blasting pattern was formerly used with disappointing results. Secondary blasting was often required and high bottoms occurred frequently; overblasting wasted drilling time, and explosives caused excessive throw. Several possible methods for improving the blast design were considered and a geophysical method was chosen for testing. There had been reports in the journals that seismic methods were being used in Europe as aids for blasting design. A literature search turned up work by Haxby 1/ on use of a refraction seismograph for measuring pit bench rock strength. Using his work as a springboard, equipment was purchased and a program was planned and carried out for developing, evaluating and implementing the seismic method for routine mine use. Following are discussions of the development program and results.

Jan 1, 1974

By K. N. Han, H. C. Cho, R. Kim

"As an extension of the work on the effect of OH- on various cations in hydrometallurgical systems, the effect of Cl-, Br-, I- and CN- on cations such as Ag+, Cd2+, Hg2+, Cu+, Cu2+, Co2+, Zn2+, Pb2+ and Sn2+ has been examined in detail. The Newton-Raphson technique has been used to determine the amounts of various metal species as a function of the concentration of anions. Some practical implications of various metal complexes in metal separation and removal from solutions have been examined and discussed.IntroductionUnderstanding the role of anions in hydrometallurgical processes often determines the success of an operation. The successful choice of concentration and type of anions not only leads to an effective extraction and removal of metals (Esmaeili et al., 2005; Brbooti et al., 2011; Wei et al., 2005; Jeppesen et al., 2009; Al-Tarazi et al., 2004), but also to assisting effective separation of various metals, whether it is a solvent extraction, ion exchange operation or even a simple precipitation (Farha et al., 2011; Sevenich and Fritz, 1983; Rashid, 1974).This paper continues the discussion of the role of anions in hydrometallurgical systems beyond the role of OH-, which was the topic of a previous paper (Kim et al., 2014). Table 1 lists various anions that are frequently used in conjunction with metal ions to be selectively separated or precipitated. As seen in the table, many anions are used frequently in hydrometallurgical practices. Some of the more frequently used anions include OH-, SO4 2- and CO3 2-. The halogen elements, Cl-, Br- and I- , as well as CN-, are also used in hydrometallurgical applications, especially in relation to noble metal recoveries (Meng and Han, 1994; Zhang et al., 1996; Sun et al., 1996; Starovoytov et al., 2007)."

Jan 1, 2015

By P. Schumacher, M. Fein

"INTRODUCTION Newmont’s Twin Creeks operation, part of its Nevada operations, produces gold from two large open pit mines. Mined ore is processed at one of three on-site facilities: a refractory mill with two autoclaves, an oxide mill and heap leaching facilities. Twin Creeks also processes various off-site sourced concentrates and ore including high grade underground ore from the Turquoise Ridge joint venture with Barrick Gold Corporation. This paper discusses Twin Creeks’ strategic mine planning process which is part of an in-depth continuous improvement program called “Full Potential.” The process involves cost analysis, phase design validations, life-of-mine production scheduling optimization, mill blending strategy and stockpile management. Through this Full Potential strategic planning, Twin Creeks is creating significant value by increasing near term free cash flow and life of mine net present value (“NPV”) and achieving cost reductions. TWIN CREEKS OPERATION Twin Creeks is one of the major gold producers in Newmont’s Nevada operations (see Figure 1, 2 and 3). Located approximately 15 miles north of Golconda, Twin Creeks produced approximately 28 % of the Nevada operation’s 2013 gold production of 1.8 million ounces (Newmont 2014). The production included Turquoise Ridge sourced gold ore from the joint venture (75% Barrick Gold Corporation, 25% Newmont).At Twin Creeks, there are two large open pits, named Mega Pit and Vista Pit (see Figure 4, 5 and 6). There are 3 to 5 phases in Mega Pit and 2 to 5 phases in Vista Pit depending on the gold price assumption. There is also an underground exploration project at the bottom of the Vista Pit. Twin Creeks produces gold from a variety of ore types requiring different processing techniques depending on economic and metallurgical characteristics. To ensure the best use of processing assets, engineering and processing groups at Twin Creeks utilize a Mixed Integer Linear Programming (“MILP”) model to guide the flow of mine sequences and material routing to various process facilities (Kawahata, Schumacher and Hufford 2013)."

Jan 1, 2015

By John A. L. Campbell

Although there has been an increased interest in the electrokinetic properties of coal (1) research on the subject is still in an early stage of development (2,3,4,5,6,7) To the author's knowledge, no electrokinetic studies have been made on coal lithotypes - particularly anthracite lithotypes. This paper presents the results of an investigation of the double layer properties displayed at the anthracite/water interface (whole coal and lithotypes) as determined by streaming potential methods, It is hoped that this investigation and related future investigations will provide correlations from which the surface properties of any coal can be predicted and then related to surface dependent processes such as froth flotation and flocculation. Another aspect of this research, undertaken to determine the physical and chemical parameters necessary for anthracite lithotype differentiation, was previously published (8). The number of parameters involved, lithologic, organic and inorganic, and the wide divergence of these parameters within an individual coal limits the practical utilization of the results, however, the results are of value and of interest in guiding theoretical developments. Keeping the limitations in mind, the results are analyzed in terms of their application to froth flotation processes and are used to indicate the feasibility of making a lithotype separation by flotation.

Jan 1, 1969

By I. E. Odom

The rare magnesium-lithium clay mineral hectorite occurs at many places in the McDermitt caldera of Nevada-Oregon. Commercial development of several high purity deposits began in 1986. The hectorite was precipitated in a lake environment formed after collapse of the McDermitt caldera. Hectorite beds and lenses are associated with volcaniclastic sediments, limestones, dolomites, zeolites and locally sandy bentonites. The high purity deposits appear to be associated with hydrothermal areas. The hectorite consists of extremely small flake-shaped crystals, and Ca is the predominant exchangeable ion. Its color ranges from white to light green. Commercial uses developed to date include high brightness magnesium aluminum silicate products, organophilic clays, pulp retention, and ceramics. The MAS is used as a suspending agent, binder, stabilizer and thixotrope in aqueous solutions for cosmetics, household cleaners, pharmaceuticals and miscellaneous industrial applications. Organoclays are used in printing inks and paints.

Jan 1, 1992

By D J. Bradshaw

It is well known that the chemical environment determines the success of the flotation process, however its characterization and control is difficult to achieve. This work evaluates the use of various measurements, including mineral potential measurements, in gaining an understanding of the influence of varying parameters such as the milling media and the reagent suite composition on the flotation performance of a platinum group metal (PGM) bearing ore. The results showed differences in the response of the various mineral electrodes to the different conditions, however the changes in flotation performance of the different minerals in the ore could not be wholly described by the electrochemical changes, demonstrating the limitations of these measurements.

Jan 1, 1999

By K. Saberyan

A technique is described for the solvent extraction of zirconium. In this method, zirconium has been extracted quantitatively from 0.005 M sodium salicylate solution at pH 2.5 - 3 using 0.01 M triphenylphosphine oxide dissolved in toluene as an extractant. Zirconium has also been recovered quantitatively from 0.2 M potassium thiocyanate solution, but extractions in nitric and hydrochloric acids (as media) were negligible. The resulting extracted metal ion has been stripped with sulfuric acid (0.5 M) and determined with inductively coupled plasma atomic emission spectrometry. This method has been applied successfully to achieve 95% recovery of zirconium from zircon concentrate.

Jan 1, 2010

By T. McNulty

The author was privileged to find employment as a uranium mill chemist for The Anaconda Company while working his way through school in the mid-1950s. He then served Anaconda in various technical and management positions until 1980. This paper describes the prevalent technologies employed by uranium producers, briefly describes various mines and mills in the U. S., and memorializes a few of the thousands of men and women who contributed to the U. S. Uranium Boom. Following isolation of uranium as an element by M. H. Klaproth in 1789, uses of uranium were confined primarily to pigments, glass coloring agents, and ceramic glazes. In 1896, Antoine Becquerel found that uranium is radioactive, releasing particles and energy as it decays. In 1898, Pierre and Marie Curie isolated radium from uranium and learned that it can be an effective treatment for some types of cancer. In 1939, it was discovered that the isotope U235 is fissionable1 . Up to this point, nearly all uranium production was from pitchblende concentrates made in Bohemia, Canada, and the Belgian Congo. In 1938, only about 5 percent (23.85 short tons) of global output was produced from ores of the carnotite mineral that were being mined in the U.S. By the early-1950s, physicists in many countries had begun to recognize the potential for nuclear chain reactions. Ernest Rutherford (UK), Frederick Soddy (UK), and Leo Szilard (US) explained transmutation of elements and formulated the principle of “atom splitting”. In 1934, Marie Curie’s daughter, Irène, and her husband, Frédéric Joliot, identified uranium as the most viable source for this new form of energy. The basic fission process was unraveled by German scientists in December 1938. After Hitler’s army seized the uranium deposits in Czechoslovakia, many feared that Germany would build the first nuclear weapon.

Mar 2, 2022

By John B. Wright

This paper describes laboratory techniques and subsequent results of Bureau of Mines research to produce chlorination-grade feedstock from an abundant, low-grade, domestic, rock ilmenite ore. The research is part of the Bureau-effort to devise technology that may help decrease U.S. dependence on imported raw materials. A rock ilmenite containing about 46 wt pct Ti02 was smelted in an electric arc furnace with coke, woodchips, and Na2C03 to separate most of the iron as pig iron and to form a low-iron, titanium-enriched slag. The slag was ground, pelletized, oxidized, and then sulfated with mixtures of SO2 and air in a continuous 4.5- to 9.1- kg/h apparatus at 1023 to 1223 K. The sulfated slag, containing 60 to 65 pct TiO2, was reground and leached in water at ambient temperature to decrease the combined levels of the troublesome Ca, Mg, and Mn impurities from 7.0 to 1.7 wt pct. At levels of more than 3 wt pct, these impurities contribute to operating and disposal problems, The final product was upgraded to about 84 wt pct TiO2. This material potentially is suitable for chlorination in a fluidized-bed reactor. The most favorable results were achieved with leached slag sulfated at a feedrate of 4.5 kg/h and at temperatures of 1073 to 1123 K.

Jan 1, 1984

By K. N. Han, M. C. Fuerstenau, T. B. Onlin

A mathematical model describing the concentration profile of fine particles in the axial direction in liquid fluidized beds has been developed for the removal of fine particles. A forward finite differentiation technique has been used to solve a continuity equation with a source term to predict the concentration profile and, hence the recovery as a function of time. With the aid of experimental results obtained using a fluidized bed of 3-cm diam, dimensionless parameters were identified. These parameters were used to predict the concentration profile of fine particles in fluidized beds of larger sizes. Four different sizes of fluidized beds, namely, 1.3, 3.0, 4.0, and 7.5 cm in diam, were used in this investigation. The amounts of bed particles used included 4, 8, 16, 24, 59, and 120 g, and the size of bed particles were 48x100, 100x150 and 150x200 mesh.

Jan 1, 1987

By Charles Kimbell, L. Nahai, E. Shekarchi

INTRODUCTION AND SUMMARY World mineral trade during 1960 to 1984 has shown substantial changes both in value and tonnage. Although fuel commodities dominated total mineral trade during this period, this paper will focus attention primarily on nonfuel minerals. Brazil and Australia, modest producers of iron ore in 1960, have become dominant producers and exporters, together accounting for about half of major iron ore exports in 1984, far surpassing traditional export suppliers such as Sweden. Australia has also become the largest producer and trader of bauxite and alumina, and worldwide alumina trade has increased at the expense of bauxite trade. Similarly, shipments of ferroalloys have increased more than shipments of ores such as those of chromium and manganese. Canada, retaining its first rank in world export of zinc, has become also the leading source of potash and sulfur in world trade, and South Africa has been the dominant factor in chromite, manganese and their respective ferroalloys. Developing countries' share of world copper trade has increased, with Chile maintaining first rank, but developed industrialized countries have continued to dominate production and trade of lead and zinc. Phosphate, sulfur, and potash have been the principal crude nonmetallic minerals traded worldwide. Looking to the near future, dramatic increases in export of iron ore, phosphate, potash and sulfur are not envisaged. Bauxite exports will continue to decline relative to alumina but at a slower rate than in the recent past. Zinc concentrate will continue to be exported but lead will be traded more as metal than as concentrate. For iron and steel, there will be some production shift from traditional producers to certain developing countries and recently industrializing developing countries such as Brazil, India, the Republic of Korea, and Taiwan. In the following sections dealing with specific commodities, it should be understood that information is presented only on the major forms of each commodity that move in trade, and only for a selected group of countries for each commodity or major form of each commodity. Thus, totals shown or mentioned generally represent only the totals of figures presented here and do not include estimates for minor forms of material or for countries that are not listed. However, the data provided is regarded as sufficiently complete to reflect major patterns and trends, and exclusions are there- fore not seen as affecting conclusions that may be drawn from the material provided. FUEL AND NONFUEL TRADE Values of Fuel and Nonfuel Trade The value of world export trade in major mineral commodities (ores, concentrates and scrap, crude minerals, iron and steel, nonferrous metals, nonmetallic minerals and mineral fuels) in 1983, the latest year for which comprehensive data are available, was reported by the United Nations in May 1985 to have totaled over 514 billion current U.S. dollars (Table 1). This was 79% of the historic record high of nearly $649 billion ,current dollars set in 1980, but almost 18 times the current dollar value reported for 1960. [1/] The value of these 1983 exports in constant 1960 dollars was $164 billion (Table 2), only 66% of the record 1980 high of almost $250 billion, and only about 5.7 times the 1960 dollar level.

Jan 1, 1986

By Chester A. Rowland

La conminución de Ios minerales es, generalmente, una etapa de preparación de la alimentación para las subsiguientes etapas del proceso. La molienda, fase de conminución de productos finos, requiere una gran inversión de capital y frecuentemente es el área de máxima utilización de potencia y de materiales resistentes al desgaste. La molienda se produce normalmente en tambores rotativos que utilizan un medio de molienda que se pierde en la misma, al elevarse con la rotación del tambor, se rompe el mineral por combinación de los efectos de impacto, atrición y abrasión, hasta producir el producto especificado. El medio de molienda pueda ser: - El propio mineral (molienda autógena - primaria y secundaria). - Medio no metálico, natural o fabricado (pebbles) - Medio metálico (barras o bolas de acero) Este capítulo tratará de molinos de barras y bolas que utilicen medio metálico de molienda.

Jan 1, 1982

By Gordon Clark, Basar Arioglu, Zlatanic. Sanja, Nasri Munfah, Togan. Tolga

"The 13.2 m external diameter double deck Istanbul Strait Road Tube Crossing is one of the most challenging underwater tunnel projects in the world. Subjected to 11 bars of hydrostatic pressure, variable geology, and being in a very active seismic area, the execution of the project required innovative solutions, sophisticated construction techniques, and prudent risk management approach. The 5 km tunnel consists of 3.4 km TBM bored tunnel, 1 km twin NATM tunnels, and cut and cover sections. The project is being delivered in a Build-Operate-Transfer (BOT) contract in a public-private partnership. The technical challenges, coupled with financial and commercial risks required the implementation of sophisticated risk management tactics including the provision of Independent Design Verification. Presently, the project is in its advanced stages of construction with a recent successful TBM breakthrough on August 22nd 2015. The paper presents the technical challenges of the project from the design, construction, and risk management aspects and provides the status of the construction. PROJECT BACKGROUND The $1.245 billion Istanbul Strait Road Tunnel Crossing project, dubbed the Eurasia Tunnel, is one of several major infrastructure projects being implemented in the Republic of Turkey in a public-private partnership approach. The project provides a direct and easy connection between the Anatolian (Asian) side of Istanbul and the heart of its historical district on the European side across the Bosphorus Strait which connects the Black Sea with the Sea of Marmara. Upon its completion in 2017, the project will improve connections to a wide network of motorways on both sides, increase capacity across the Bosphorus by 100,000 vehicles a day, reduce congestion and save motorists an average of 45 minutes of commuting time in each direction, and bringing significant economic benefits to the city and the region; it will ease traffic across the strait, reduce congestion, decrease pollutants and emission while maintaining the historical silhouette of the city. Figure 1 provides a general view of the project location and alignment. The overall project consists of three parts totaling 14.6km. Parts 1 and 3 consist mainly of widening existing motorways, providing connections to existing roads, reconstructing local bridges and underpasses on the European and Anatolian sides respectively. Part 2 is the tunnel crossing across the Bosphorus; it is the most complex part of the project with the greatest challenges and risks. Part 2 is 5.4 km long consisting of 3.4 km of 13.2m external diameter TBM bored tunnel under the Bosphorus Strait, 1-km of twin NATM tunnels on the Asian side, cut and cover transition boxes in the Asian and the European sides and depressed approaches on both sides. In addition, this segment includes the toll plazas, ventilation buildings, and the tunnel control and maintenance facilities."

Jan 1, 2016