RMZ – MATERIALI IN GEOOKOLJE

436 Kos, A., Dervarič, E.the best possible yield of material froman advance section. Lower distancesbetween horizontal cuts have been increasedin order to obtain blocks ofmaximum height dimensions for furtherprocessing. Certain horizontal cuts canbe omitted, but due to the structure andcracking of the site, this might aggravatethe work and increase the exploitationcosts. As excavation at higher levels ismore difficult, the distances betweenhorizontal cuts are increasingly smallerwith height. In the excavation of naturalstone from quarries of Marmor, Sežana,d. d., the cutting geometry as illustratedin Figure 4 is used. Sometimes, a horizontalcut can be omitted, contributingto a better yield from an advance section.Selection of equipmentQuarry equipment requires careful selection,as the use of unsuitable equipmentsignificantly increases excavationcosts.Before selecting the machines, the followingresearch should be done:• geological studies must be made toestablish the geological structure,reserves and quality of the mineralmaterial,• geomechanical studies must bemade to establish the physical andmechanical parameters of the material,strength, abrasiveness, possibilityof swelling, chemical andmineral structure.Before selecting the equipment, an appropriateexcavation method shouldbe selected; i.e. either surface or undergroundexcavation. On the surface,a method of excavation from top tobottom is used; the height of exploitationfloors is usually 3 m to 6 m. Inunderground excavation, the combinedFigure 5. Open surface and underground excavation - Lipica 1 quarry.RMZ-M&G 2012, 59