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By Anna Sieminska-Lewandowska, Monika Mitew-Czajewska

"The construction of 6.3 km long central part of 2nd metro line in Warsaw was completed in September 2014 (7 stations - out of which three 25m deep stations - built using cut and cover method; two single-track tunnels constructed using four EPB TBMs as well as a short NATM section with soil freezing below the existing road tunnel). Central section of the 2nd metro line was opened to public after verification and testing in March 2015. Design and build tender for the extension of this line in East (three stations) and West direction (three stations) was announced with total length of running tunnels – approx. 5 km. Detailed description of a very complex geotechnical context, different construction methods, challenges encountered and solved during construction and finally lessons learnt on this interesting project are presented in the paper. DESCRITPTION OF THE PROJECT Introduction The very first concept plan of the metro system in Warsaw was designed several years after regaining independence by Poland in 1918. In 1929, following the geotechnical survey, design works begun, but the economic crisis of the 1930s stopped it. After a few years of break, in 1938 a coherent concept of the metro network was proposed to be implemented in phases over the next 35 years. In total, construction of 46 kilometers of metro, including 31 km of tunnels and 15 km on surface, was planned. Unfortunately, World War 2 made the implementation of those plans impossible. In the post-war period several metro designs were elaborated, but none except one was scheduled for implementation. Construction of the 1st, 23.1 km long, North-South line commenced in 1983 and finished in 2008 (Sieminska-Lewandowska et all. 2009). Nowadays, Warsaw covers the area of 517 km2 and, according to year 2014 statistical data, the city has much more than 1.7 million inhabitants. Only one operating metro line is not sufficient for such a populated city. Up-to-date metro plan, shown on Figure 1, includes also 30.5 km long 2nd metro line. It’s route is divided into four sections: Western Section with the length of approx. 9.2 km and 9 stations, Central Section with the length of 6.3 km and 7 stations, North-East Section with the length of 7.7 km and 6 stations, South-East Section with the length of 7.1 km and 6 stations. The construction of the central part of the 2nd metro line in Warsaw was completed in September 2014 and its operation started in March 2015. The paper focuses on challenges encountered and solved and lessons learnt during construction of the central part of the 2nd metro line in Warsaw."

Jan 1, 2016

By Richard R. Klimpel

In this paper, the old and the new commercially available reagent chemistries for the improved flotation of sulfide minerals will be summarized. The reagent classes discussed are those that meet three criteria: 1) they are being commercially used and/or large scale plant tested in North America in the last few years; 2) they are clearly different in chemical structure than commonly used commercial reagents of the last few decades and are not simply mixtures of existing reagents and/or simple changes in cation, alkyl group size, etc. and 3) the structural formulae are clearly specified in the public literature.

Jan 1, 1994

By R. E. Johnson, L. V. Araújo, B. R. Palmer, L. M. Abrantes, G. W. Warren

The behaviour of chalcopyrite - mineral specimens and a Portuguese concentrate - in 2M chloride solutions prepared from hydrochloric acid and sodium chloride, has been characterized by cyclic voltammetry. The study has shown the influence of the potential and of the presence of impurities in the reaction schemes and their relative extent. The dissolution of chalcopyrite concentrate under potentiostatic control has been investigated and found to confirm the effect of the selected potential on the surface modification/rate of dissolution. An attempt has been made to correlate the information obtained with the response of the concentrate electrode to constant current treatments.

Jan 1, 1993

By Hugh W. Rimmer

The design of comminution circuits and the evaluation of alternatives should be based on state-of-the-art equipment and appropriate design criteria - considerations that are often neglected by today's designers. This paper critically reviews common circuit designs, evaluates various alternatives for difficult-to-treat ores, and discusses the factors that should be considered when developing new plant designs or auditing existing plant performance. Data obtained from laboratory, pilot and plant-scale test work on a wide range of ores and circuits are used to justify the author's conclusions.

Jan 1, 1995

By D. J. Dunn

Grinding balls, simple in shape, are actually sophisticated machine components and essential elements of mineral grinding mills. Their physical properties and quality must be adequate to achieve design life and grinding mission with few failures. Consistent properties and freedom from breakage are essential. Size, mass, hardness profile, chemistry, and microstructure are important variables that should be designed, specified, controlled, and verified to achieve optimal mill performance. Failure to specify ball properties in detail or failure to obtain required ball properties and quality can cause milling productivity losses and excessive costs that could endanger a milling operation's survival in the competitive mineral industry.

Jan 1, 1990

By R. Gehauf

Magnetic separation using rare earth rolls (RER) and rare earth drums (RED) have seem tremendous development and use in recent years. While the process of magnetic separation is understood, the principles affecting the separation, the specific application and the optimization of RERs and REDs are less well known. This paper offers practical insight into the basic operation, selection and optimization of RERs and REDs. It is a guide for the engineer who must design a test series and select the proper equipment for that application. It provides the engineers and line operators who control the daily operation of the equipment a basic understanding of the dynamics of operation and the principles that govern the optimization of RERs and REDs.

Jan 1, 2004

By Michael E. Kelahan, Glenn A. Gruber

A review of recent phosphate beneficiation developments shows that Flotaire cells, ranging from 0.20 m to 2.44 m in diameter, have been examined in pilot scale and commercial plants. Applications of the column cells have included sized feed fractions using anionic and cationic reagent systems. In plants where the Flotaire was installed as a test unit or as an optional circuit, its use has been largely discontinued. On the other hand, when management committed to installing the Flotaire as an integral part of the flowsheet, the performance expectations were met or exceeded.

Jan 1, 1988

By G. H. Schnakenberg

In 1986, the US Bureau of Mines (USBM) embarked on a major research effort to develop technology that could substantially reduce worker exposure to face hazards by simply relocating the equipment operators to an area of relative safety. This reduced-exposure mining system (REMS) research effort enhances the USBM's ongoing health and safety efforts aimed at reducing and controlling dust and noise and reducing accidents through training and better mining practices. This paper reports on the progress made on the developing research and demonstrates the technologies required for the computer-assisted teleremote operation of continuous mining machines, haulage systems and roof bolting machines.

Jan 1, 1998

By Arpad E. Torma

The electrochemical behavior of a zinc sulfide concentrate during the microbiological leaching was investigated using ZnS-carbon paste electrodes and a cyclic voltametric technique. The effects of Zn2 [ ] , Fe2+, Fe3+ and Cu2+ on the cathodic and anodic currents associated with zinc sulfide leaching in presence and absence of microorganisms, were assessed. The semiconductor nature of zinc sulfide was discussed in terms of ability of microorganisms to obtain their metabolic energy (through removal of electrons) from this high energy gap substrate. The intermediate electrochemical reactions involved in the ZnS leaching were described.

Jan 1, 1989

By Noel N. Moebs, John L. Ellenberger

Geologic structures in mine roof rock contribute to many roof falls in Appalachian coal mines. These structures include paleochannels, scours, pinch-outs, slickensides, clay veins, and cravasse splays consisting of thinly interlaminated sandstone and shale. These structures often can be identified during, and sometimes before, development and mine projections can be revised to reduce the adverse effects of discontinuities in roof structure. Large areas of roof consisting of laminated sandstones or incompetent strata generally can be delineated from exploratory drill-hole data and the need for supplementary support can be anticipated. Because an accurate description of roof geology also provides some indication of optimum length and type of roof bolts that should be installed, this Bureau of Mines paper describes the hazardous roof structures most commonly encountered in the Appalachian coal region.

Jan 1, 1982

By A. Unal, R. L. Grayson

The use of radio frequency identification (RFID) technology to solve informational needs in isolated and restricted underground mining environments are reviewed, and the specifications of some of the past and currently available systems are presented. The advantages and disadvantages of using various frequencies, system configurations and specific components, including their construction standards and capability, are also discussed. The remaining challenges to the more widespread use of RFID systems for personnel and vehicle tracking are identified, and recommendations concerning the operating environment capabilities are detailed. Finally, the ultimate requirements for maintaining system integrity during and following a coal mine emergency are discussed.

Jan 1, 1999

By Ulf Marklund, Stig Markstrom

Pioneering work with pilot scale autogenous grinding started in Boliden 1956. From 1961 to 1991 eleven fully autogenous grinding (AG) circuits have been installed at various concentrators within the Boliden company. A compact two-stage grinding system was de- signed in the beginning of 1970s. The system included a pebble extractor which feed the secondary grinding stage with grinding media. The APC grinding system (Autogenous/Pebble/Crusher) is a further development of the AG concept. A new design of the Boliden pebble extractor together with improved control strategy make the performance of the APC system suitable to almost any ore quality. The Boliden AG concept is probably the most cost efficient grinding system of today.

Jan 1, 1998

By Yoginder P. Chugh, K. V. K. Prasad, R. Missavage

This paper presents results of field monitoring and finite element studies to analyze and improve a room-and-pillar retreat mining system. Fie1 d instrumentation was utilized to monitor pi11ar load changes, roof to floor convergence and differential roof strata movement as retreat mining progressed and to determine in-situ horizontal stresses. A two-dimensional finite element model depicting strata behavior at this mine was developed and used to analyze existing and alternate improved mining geometries. The results showed excellent correlation between fie1 d observed and model predicted behavior. Some of the recommended changes in mining geometry based on the study were incorporated in the mining system.

Jan 1, 1986

By L. Xiao, P. Somasundaran

Three major types of solution chemical equilibria-involving minerals, solution, and flotation reagents such as collectors, frothers and modifiers-play a crucial role in determining the behavior of complex flotation systems. Minerals of phosphates (apatite and francolite), tungsten (wolframite and scheelite) and associated carbonates (calcite and dolomite) are sparingly soluble in aqueous solution and form dissolved mineral species in bulk solution. Such dissolved species interact with mineral solids, often resulting in surface conversion of the minerals. In addition, they can interact with various floation reagents and lead to surface or bulk precipitation and loss of selectivity in the flotation. Relevant solution equilibria of such sparingly soluble minerals and their interactions with oleic acid and structurally modified reagents were determined in this study using a multi-pronged experimental approach. Methods to manipulate and control the solution chemical equilibria and thus achieve selectivity in flotation systems are discussed.

Jan 1, 1992

By J. M. Mutmansky

The objective of this study was to produce coal dusts for laboratory research that are similar to mine airborne dusts in chemical, mineral, and physical characteristics. In this investigation, dusts produced in laboratory comminution equipment were compared with continuous-miner-generated dust for similarity in physical characteristics. Mining-generated dust (MGD) and bulk coal samples were first collected from an underground mining operation. The bulk samples were then processed in the laboratory for size reduction in various comminution devices. These laboratory-generated dust (LGD) samples were subjected to size and microscopic analyses. Physical properties of the dust particles were studied on a scanning electron microscope (SEM). A numerical shape coordinate system (SCS) was also developed and applied to 300 particles from each sample. Statistical analysis was then performed on the collected data and characteristics of the MGD and LGD samples were compared.

Jan 1, 1995

By S. L. Patil, D. E. Walsh

A novel form of calibration of on-line analyzers was implemented. Rather than simple equations, a neural network was used to model the relationship between the scintillation counts (Am and Cs) of an analyzer, and the measured ash for improved on-line analysis of run-of-mine (r.o.m.) coal. Also, a new approach was followed to better evaluate neural network performance. Samples were first divided into various statistically different groups using a Kohonen network. Data was then selected for the training, calibration and prediction subsets, using criteria developed in this paper for sparse data, with representation from each group. A backpropagation based neural network architecture was used in conjunction with quick stop training. Due to noise in the data, the predictions were very good on average, but not individually.

Jan 1, 2003

By D. G. Millette, A. J. S. (Sam) Spearing

The design of a cost effective backfill system involves many aspects and various inputs from different engineering disciplines. Backfilling is a very significant mining cost and efforts need to be made in the design stage to maximise efficiency and flexibility whilst minimising costs. The aspects that need to be considered include the following: Required fill performance underground Peak and average fill tonnage requirements Backfill scheduling in the mining cycle Material selection, testing and preliminary costing Plant design and storage needs Infrastructure requirements Implications on surface waste/tailings disposal and costs Total backfill costs In order to produce a cost effective and efficient backfill operation, a multi-disciplinary project team is required that should include the following skills and functions: Mine Planning Rock Engineering Metallurgy Mechanical Engineering Environmental Health and Safety Tailings Disposal/Waste Management This paper discusses the above and indicates important aspects that should be considered.

Jan 1, 2001

By H. F. Hennigar, D. L. Pawson, E. J. Foell

Results of an analysis of abyssal benthic megafauna based upon review of nearly 250 hours of videotape and 2149 bottom photographs are presented, and the utility and limitations of such analyses in deep sea biological studies are discussed. The images were acquired at depths of 4400-4800 m during a resource assessment cruise aboard the RV Prospector using a unique, deep-towed, television telemetry system coupled with 35-mm photography. The data review was carried out in support of NOAA efforts to provide adequate environmental baseline information before industrial exploitation of nodule deposits and concurrent monitoring begin.

Jan 1, 1991

By R. Hemp

This paper describes work carried out to obtain a heat balance in the B3 shaft longwall stope at Blyvooruitzicht gold mine. Recordings were made of the temperature of the air and chilled water entering and leaving the section during three periods, August 1 September 1977, November 1 December 1977 and March 1978. These recordings, together with numerous other measurements were used to determine the rate at which heat was being removed from the section by the various fluids flowing through the section. The rate at which heat was entering the section was then calculated, by considering each source in turn. These two sets of figures made it possible to draw up a heat balance, and also obviously gave vital information on the magnitudes of the various heat sources and on the methods used to remove heat. In general reasonable heat balances were obtained, the errors being in the range -6 per cent to +22 per cent.

Jan 1, 1980

By Cliff G. Paton, Sheldon B. Bland, Roger E. Melley

This paper looks at four critical lubricants used in the conveyor systems of the northern Albertan oil sand facility. The requirements for the lubricants used in the electric motors and gear boxes of the drive systems, the pulley bearing and the idler bearings are discussed in terms of the applications and the environment. A number of developments that have occurred in recent years are presented. Data from the field and from custom designed testing in the laboratory are used to support the role of simulation testing in problem solving in this area of technology.

Jan 1, 1996