Vol. 16, Issue 1 (Jan-June 2006)

Abstracts

• Elias Stamboliadis, Georgios Alevizos and John Zafiratos (Technical University of Crete, Department of Mineral Resources Engineering, GR-731 00 Chania, Crete, Greece): "Characterisation and beneficiation of laterites leaching residue." Mining & Metallurgical Annals, vol. 16, no. 1, Jan-June 2006, pp. 23-40.

The lateritic nickeliferous iron ore deposits of Central and Northern Greece (Euboea, Locris, Boetia, and Kastoria) provide the feed material for the production of an iron-nickel alloy at a pyro-metallurgical plant located in Larymna. Due to the low quality of the feed ore, about 1.0-1.1% nickel, the cost of the metallurgical process is high and the quantity of the slag produced and disposed amounts to millions of tonnes yearly. During the last years a novel method of hydrometallurgical processing of laterites has been developed at the Laboratory of Metallurgy of NTUA. The method is based on heap leaching of the ore with dilute sulphuric acid and nickel is recovered from the pregnant leach liquor by solvent extraction and electrowinning.

The solid leach residue is a material consisting mainly of hematite, quartz and chromite. The present research is an investigation on the upgrading of the solid leach residue to a saleable iron concentrate. If proved successful, it will potentially relieve the environment from the disposal of such a large quantity of slag, which today is produced by the pyrometallurgical processing of laterites. The accomplishment of this target faces problems related mainly to the fine dissemination and interweaving of mineralogical phases and the present work is focused to addressing the associated mineralogical issues.

In brief, the ore was crushed to -10 mm and pelletized to allow sufficient permeability during column leaching with 2 N sulphuric acid. The solid residue of leaching was scrubbed and classified to different size fractions for magnetic separation. The rejected non-magnetic material consists mainly of quartz, while the magnetic product consists of low quality hematite due to the finely disseminated inclusions of quartz and some chromite. This magnetic product was ground to -70 ìm and treated again by magnetic separation. In this case, the liberation of hematite is good but the magnetic separation is not selective. Froth flotation is recommended for this separation and it is aimed for a future work.

An important finding of the present work is the detection of sub-micron kaolinite finely disseminated in hematite. Kaolinite is not visible by a microscope and is not detected by X-ray diffraction. Its existence is determined by electron-microscopy analysis, which shows the presence of Al and Si in the mass of hematite grains. The quantitative relation of Al to Si is the same with that found in kaolinite. The above finding means that a clean hematite concentrate may be not possible to be recovered after the separation of quartz from hematite.(Article in Greek.) © Mining & Metallurgical Annals, Hellenic Society of Mining & Metallurgical Engineers, 2006.

• Katerina Adam (ECHMES Ltd., Mikras Asias 40-42, GR-115 27 Athens, Greece): "Management of mining projects and sustainable development." Mining & Metallurgical Annals, vol. 16, no. 1, Jan-June 2006, pp. 41-60.

The basic concepts of Project Management applied for the sustainable development of the mining industry are summarized in the present study. Critical parameters such as the design, stages of development, time schedule, as well as the organization of the various resources, are initially presented in a generic framework, and then focusing in mining projects. The individual stages foreseen from the prevailing mining and environmental legislation, from the stage of conception, till the completion of extraction activities and reclamation of the closed mining sites are analytically presented and in the form of diagrams. As a case study for the application of the Project Management principles in the mining industry, the main development stages of a mining project currently developed in Greece is presented. (Article in Greek.) © Mining & Metallurgical Annals, Hellenic Society of Mining & Metallurgical Engineers, 2006.

• Konstandinos Modis and Georgios Papantonopoulos (National Technical University of Athens, School of Mining and Metallurgical Engineering, GR-157 80 Zographos, Attiki, Greece): "Least squares estimation, kriging, and modern geostatistics: different faces of the same philosophy?" Mining & Metallurgical Annals, vol. 16, no. 1, Jan-June 2006, pp. 61-75.

The objective of this paper is the investigation of the common scientific background and the philosophy that lies under the application of least squares regression methods, kriging and modern geostatistics for the estimation of the spatial distribution of natural variables. Thus, under the light of geometrical representation it is proved that in the case of normal random function the kriging algorithm can be analysed in a series of linear regressions. Along the same reasoning, the transition to modern geostatistics is also explained. Modern geostatistics as expressed through the BME methodology solve the problem of estimation for any probability distribution of the random function. For the better understanding of these notions an application of BME is presented for a linear interpolation problem. (Article in Greek.) © Mining & Metallurgical Annals, Hellenic Society of Mining & Metallurgical Engineers, 2006.

• Antonis Antoniou and Zacharias Agioutantis (Technical University of Crete, Dept. of Mineral Resources Eng., GR-731 00 Chania, Crete, Greece): "Determination of the perimeter of the pit bottom in surface mining operations." Mining & Metallurgical Annals, vol. 16, no. 1, Jan-June 2006, pp. 77-91.

The determination of the perimeter of the pit bottom in surface mining operations and the respective design of the final bench configuration are inherently related to the overall pit design. In this study, an alternative technique to calculate the pit bottom perimeter and the respective pit limit geometry is proposed that is based on multiple circles drawn from the pit boundary points. This technique is compared with the method of parallel sections as well as with the central point method. The technique is presented as a working example based on the design of the Medcon Construction Ltd. quarry of aggregate materials in Cyprus. This technique offers significant advantages with respect to accuracy and ease of application. (Article in Greek.) © Mining & Metallurgical Annals, Hellenic Society of Mining & Metallurgical Engineers, 2006.

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