Vol. 13, Issue 1-2 (Jan-Dec 2003)

Abstracts

• Konstantinos G. Tsakalakis (National Technical University of Athens, School of Mining and Metallurgical Engineering, Section of Metallurgy and Materials Technology, Laboratory of Mineral Processing, GR-157 80 Zografou, Athens, Greece): "The Greenhouse Effect and the impact of fossil fuel burning and the other anthropogenic activities on its evolution." Mining & Metallurgical Annals, vol. 13, issue 1/2, Jan-Dec 2003, pp. 23-49.

In this work, the Greenhouse Effect is concisely analyzed, the processes contributing to the increase of the global surface temperature are described and their expected future impact on the climate and the environment are highlighted. With data from the global and the per-geographic-region consumption of conventional fossil fuels, a calculation of the global CO2 emissions through approximate methods is presented. From the review of the energy consumption and the CO2 emissions, it is realized that, from a population point of view, there is a disproportional energy consumption and contribution to the global CO2 emissions by the industrialized countries (N. America, European Union, Oceania, Japan and S. Korea). It is also observed that there is a continuous increase in energy consumption and CO2 emissions in the developing countries (China, India). From the whole analysis presented herein, the interest of industrialized countries, which in most cases are insufficient in fossil fuel reserves for their current and future needs, for the energy resources of the developing countries (Middle East, Africa, former Soviet democracies of the Caspian region, Latin America) becomes evident. The commitments adopted in Kyoto (1997) for the reduction of the greenhouse gases emissions by an average 5.2% during the period 2008-2012 to the 1990 levels, are difficult to be achieved. The need of concentrated efforts towards the development of suitable strategies for the reduction of the environmental consequences from the energy production and use seem also inevitable. These strategies should always aim at the principles of the sustainable development. (Article in Greek.) © Mining & Metallurgical Annals, Hellenic Society of Mining & Metallurgical Engineers, 2003.

• Dimitrios Mendrinos (Centre for Renewable Energy Resources, Geothermal Sector, 19th km. Marathonos ave., GR-190 09 Pikermi, Attica, Greece), Athanasios Roris (Aristotle University of Thessaloniki, Department of Physics, University Campus, GR-540 06 Thessaloniki, Greece) and Konstantinos Karytsas (Centre for Renewable Energy Resources, Geothermal Sector, 19th km. Marathonos ave., GR-190 09 Pikermi, Attica, Greece): "Heating of new buildings of the Thessaloniki International Airport-Macedonia with geothermal energy." Mining & Metallurgical Annals, vol. 13, issue 1/2, Jan-Dec 2003, pp. 51-58.

Geothermal research made in the region of the Thessaloniki International Airport-Macedonia, showed that the use of geothermal energy in heating of the airport's new complex is clearly feasible. It is estimated that a combination of one borehole providing 75 m³/h of water at 42°C, with water source heat pumps, can cover 75% of the thermal requirements during the winter. If the system contains cooling towers, it can contribute to the highest degree to the airport's air conditioning. Although the capital cost of this system is higher than that of a conventional system (air-source heat pumps or their combination with diesel boiler), its maintenance and operating cost is much lower. This fact, along with other economic indices, like the payback time (8.2 years), the internal rate of return (11.4%) and the net present value (€783,301 after 25 years), makes the proposed investment extremely attractive. (Article in Greek.) © Mining & Metallurgical Annals , Hellenic Society of Mining & Metallurgical Engineers, 2003.

• Spyridon Economou, George Papapanos, Nikolaos Petsas and Michalis Vardavoulias (Pyrogenesis SA, Technological Park of Lavrion, GR-195 00 Lavrion, Greece): "Improvement of aluminum alloy machine components by thermal sprayed coatings." Mining & Metallurgical Annals, vol. 13, issue 1/2, Jan-Dec 2003, pp. 59-73.

The objective of the present study was the development of Fe-based hard coatings, deposited by electric arc spraying, capable of providing wear protection to light aluminum alloy machine components. To that end, the processing conditions were studied and optimized for achieving the desired coating structure and properties. The spraying velocity and distance, the primary gas composition and pressure, as well as the process power input, were studied. Emphasis was given to the heat management during spraying for achieving sufficient adhesion of the metallic coating on the aluminum substrate. The coatings were thoroughly characterized and classified, based on evaluation of their structure, hardness, adhesion strength and tribological behavior. The study results showed that by controlling the spraying environment and consequently the in-flight reactions that take place during spraying, the coating structure could be also controlled, which consequently influences the coating properties. (Article in Greek.) © Mining & Metallurgical Annals, Hellenic Society of Mining & Metallurgical Engineers, 2003.

• George Pagonis (Public Power Corporation SA, Kifissou and Dirachiou 89/Rosiniol, GR-104 43 Athens Greece): "Plane failures of slopes in open pit lignite mines." Mining & Metallurgical Annals, vol. 13, issue 1/2, Jan-Dec 2003, pp. 75-93.

The slope failures are one of the most serious problems of the open pit mining exploitations, because, in many cases, they endanger the mine staff, the equipment and the installations. They also may cause operation interruptions and ore losses. The objective of the article is the analysis of plane failures in open pit lignite mines. These failures are developed on clay seams of small thickness and low strength. The specific characteristics of these failures, the evolution of the phenomenon and the slope stabilization measures are presented herein. (Article in Greek.) © Mining & Metallurgical Annals, Hellenic Society of Mining & Metallurgical Engineers, 2003.

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