Modelling for degreasing the mining equipment downtime by optimizing blasting period at Erdenet surface mine

Erdenet copper-molybdenum deposit is the biggest one in the world and has a significant impact on Mongolian society and economy. Today LIEBHERR-994B hydraulic shovels from Germany, electric shovels including EKG-10 and EKG-15 from Russia operate for the mining works, and dump truck BelAZ - 75130 used for transportation. The causes of shovel downtime are classified as technical, technological, and organizational. During the study period, 41% of the total downtime of the excavator’s park was technical, 45% was technological, and 11% was organizational downtime. For shovels, 7% of technological downtime is due to blasting, and for dump trucks 8.7%. In open-pit mining, blasting is performed on a weekly basis, so the duration of this technological downtime can be considered almost constant. If the time between blasts or period of blasting can be arranged optimally, it will be possible to reduce mining equipment’s downtime due to blasting.

Protracted Magmatism and Mineralized Hydrothermal Activity at the Gibraltar Porphyry Copper-Molybdenum Deposit, British Columbia

The Gibraltar Cu-Mo deposit, with a total tonnage of 3.2 million tons (Mt) Cu, is located in the Canadian Cordillera and hosted by the Late Triassic Granite Mountain batholith. The batholith formed through multiple intrusions of tonalitic rocks over a period of ~25 m.y. beginning at 229.2 ± 4.4 Ma in the Quesnel island arc before the accretion of the arc to the North American continent. Late in its evolution, Cu fertile magmas intruded in the center of the batholith, during at least three events from 218.9 ± 3.1 to 205.8 ± 2.1 Ma. The fertile magmas were hotter and more mafic than older barren magmas. They generated magmatic-hydrothermal activity, forming potassic alteration and white mica alteration, and produced Cu mineralization as chalcopyrite-quartz veinlets and disseminated chalcopyrite. Zircon in the Cu-bearing tonalite intrusion (218.9 ± 3.1 Ma) shows high Ce4+/Ce3+ (681 ± 286 [2σ], n =15) compared to those from older barren intrusions (129 ± 56 [2σ], n = 118). Oxidation conditions for parental magmas are calculated using the compositions of zircon and amphibole. The magmas for Cu-bearing intrusions have an average of fayalite-magnetite-quartz buffer (FMQ) +1.7 ± 0.7 (2σ, n = 73), whereas those for older barren intrusions have slightly lower fO2 (avg FMQ +1.3 ± 0.5 [2σ], n = 108), although the values are overlapping for the two. The bulk rocks of Cu-bearing tonalite intrusions in the Granite Mountain batholith have low Sr/Y ratios (<22) independent of the degrees of alteration. The low ratios are also reflected by low Sr/Y in zircon, suggesting that the low Sr/Y ratios of bulk rocks represent those of unaltered rocks. The values are low compared to those associated with many other porphyry Cu deposits globally. The data suggest that igneous rocks elsewhere with low Sr/Y in bulk rocks may have a potential to host economic Cu deposits. Ratios of Ce/Nd and Ce/Ce* (=Ce/((NdN)2SmN)) in zircon are positively correlated with the Ce4+/Ce3+ in zircon from the Granite Mountain batholith. Since the former two ratios can be obtained solely from zircon composition, these ratios from detrital zircon may be useful in evaluating the occurrences of oxidized intrusions in regional mineral exploration.

Molybdenum mineralization of Serhiivka Au-Mo deposit (Middle Dnipro, Ukrainian Shield)

The article is devoted to molybdenum mineralization of the Eastern flank of Au-Mo Serhiivka deposit, located in the Middle Dnipro megablock of the Ukrainian Shield (USh). The generalized description of mineralization is performed on such important questions: discovery and exploration history, structure and composition of the host rocks, metamorphic and metasomatic alteration of rocks, structural position and localization conditions of molybdenum mineralization, ore composition, description of major ore minerals, morphology of mineralization and the most widespread views about its genesis. Molybdenum ores were discovered and named East-Serhiivka occurrence for the first time in 1974, before the discovery of gold mineralization, which occurred in 1985. Serhiivka deposit consists of two Mesoarchaean volcanic-plutonic associations (VPA) of different composition: the early mafic and the late felsic. The Eastern flank of the deposit, where the molybdenum mineralization is concentrated, is a structural knot similar to the lying letter “T”. It is formed by complex joint of the sub-latitudinal Serhiivka and sub-meridional Solone subvolcanic bodies and the East-Serhiivka massif of plagiogranitoids of the late VPA, which intrude basic rocks of early VPA. Molybdenum mineralization is localized in linearly elongated zones with a chaotic network of thin quartz, carbonate-quartz veinlets and poor (2–5 %) sulfide impregnation, including molybdenite. About 20 vein-impregnated ore zones have been recovered with up to 100–150 m thickness and 0,01 to 0,3 %, sometimes more than 1 % average molybdenum grade. The ores are subdivided into two major mineral types: 1) quartz-molybdenite; 2) quartz-sulfide-gold-molybdenite. The main components of ores molybdenite and native gold are associated with pyrite, chalcopyrite, magnetite, occasionally – pyrrhotite, arsenopyrite, scheelite, bismuth telluride, silver and others. Typical non-metallic minerals are quartz, carbonate, feldspar, chlorite, amphibole, biotite, sericite. It is supposed hydrothermal-metamorphogenic genesis of molybdenum (and gold) ores. Molybdenite and gold are rarely detected in the same intersections, which indicates separate genesis of these minerals. According to the accepted classification molybdenum mineralization is systemized as linear stockwork. Molybdenum ores of Serhiivka deposit are mostly considered as independent, separate from gold mineralization, potentially workable mine. It is the most prospective one in the Middle Dnipro region, USh and Ukraine in general. We suggest a comprehensive approach to studying, resource and reserves evaluation of Serhiivka deposit, taking into account the potential of both molybdenum and gold mineralization, as well as concentrations of rhenium and osmium in molybdenite. Geological exploration on the base of this approach will increase investment prospects of Serhiivka gold-molybdenum deposit.

Re-Os Geochronology, Whole-Rock and Radiogenic Isotope Geochemistry of the Wulandele Porphyry Molybdenum Deposit in Inner Mongolia, China, and Their Geological Significance

The Wulandele molybdenum deposit is a porphyry-type Mo deposit in the Dalaimiao area of northern Inner Mongolia, China. Molybdenite Re-Os dating yields a model age of 134.8 ± 1.9 Ma, with the fine-grained monzogranite most closely related to the mineralization. The lithogeochemical data show that the monzogranite is weakly peraluminous, high-K calc-alkaline series, with reduced to slightly oxidized, highly fractionated I-type granite characteristics. The relatively low initial 87Sr/86Sr (range from 0.705347 to 0.705771), weakly negative εNd(t) (range from −2.0 to −1.3), and crust-mantle mixing of Pb isotopes suggest that the monzogranite originated from the partial melting of mafic juvenile lower continental crust derived from the depleted mantle, with a minor component of ancient continental crust. Combined with the regional tectonic evolution, we argue that the partial melting, then injection, of the monzogranite melt was probably triggered by collapse or delamination of the thickened lithosphere, which was mainly in response to the post-orogenic extensional setting of the Mongol–Okhotsk belt; this is possibly coupled with a back-arc extension related to Paleo-Pacific plate subduction. The extensively fractional crystallization of the monzogranite melt is the crucial enrichment process, resulting in magmatic hydrothermal Mo mineralization in the Wulandele deposit, and the Cretaceous granitoids are generally favorable to form Mo mineralization in the Dalaimiao area.