Stefan Uroš II Milutin Nemanjić (1282–1321)

King Stefan Uroš II Milutin Nemanjić (1282—Donje Nerodimlje, October 29, 1321) was a Serbian medieval king, the seventh ruler of the Serbian Nemanide dynasty, the son of King Stefan Uroš I (r. 1243–1276) and Queen Helen Nemanjić (see), the brother of the King Stefan Dragutin (r. 1276–1282) and the father of King Stefan Dečanski (r. 1322–1331). Together with his great grandfather Stefan Nemanja, the founder of the Nemanide dynasty, and his grandson, Emperor Stefan Uroš IV Dušan, King Milutin is considered the most powerful ruler of the Nemanide dynasty. The long and successful military breach of King Milutin, down the Vardar River Valley and deep into the Byzantine territories, represents the beginning of Serbian expansion into southeastern Europe, making it the dominant political power in the Balkan region in the 14th century. During that period, Serbian economic power grew rapidly, mostly because of the development of trading and mining. King Milutin founded Novo Brdo, an internationally important silver mining site. He started minting his own money, producing imitations of Venetian coins (grosso), which gradually diminished in value. This led to the ban of these coins by the Republic of Venice and provided King Milutin a place in Dante’s Divina Commedia. King Milutin had a specific philoktesia fervor: He built or renovated over three dozen Serbian Orthodox churches and monasteries not only in Serbia but also in Thessaloniki, Mt. Athos, Constantinople and The Holy Land. Over fifteen of his portraits can be found in the monumental painting ensembles of Serbian medieval monasteries as well as on two icons.

Coal Flowability Control on Preventing Spillage on Conveyor Belt Through Modeling and Simulation for Improving its Performance

Belt conveyors are generally used in mining plant areas, both surface and underground mines. The belt conveyor is mainly applied to transport the extracted bulk material from the mining site to delivery. The effectiveness of the extraction process depends on the reliability and durability of the conveyor belt system. In addition, conveyor performance is very important specially to control material flowability to prevent spills or other operational disturbances to optimize production throughput. However, the transfer chute and settling zone can cause some problems during the transfer process, such as material spills. This problem can reduce the function and performance of the conveyor belt. This paper discusses a design model to reduce the problem of spillage in the settling zone. The model was developed by compiling the previous defecting data from the durability of the conveyor system, then analyzed using Discrete Element Method (DEM) software and compared with bulk characteristics. The initial performance of certain conveyors is only capable of serving with an average production of 76% of the designed capacity while energy is consumed at full load. By applying the DEM simulation result, the blade gate can reduce the peak angle break in the depositional zone before exiting. After the analysis is completed using DEM, the conveyor increases the average production to 95% of the designed capacity. In conclusion, controlling the maximum belt load without spillage will reduce interruption on conveyor belt operation and maintenance costs therefore increase plant reliability and availability.

Teresterial Background Ionizing Radiation around Lead/Zinc Mining Site in Ishiagu, Ebonyi State, Nigeria

Background ionizing radiation around Lead/Zinc mining sites at Ishiagu, Ebonyi State was carried out using appropriate equipment. The background ionizing radiation of the environment was determined by measuring the radiation exposure rates using Radalert-200 and Geographical Positioning System (GPS). Radiological health parameters and effective dose to different organs of the body was estimated. The average exposure rate of 0.00017mSv/h (0.017mR/h) measured was relatively higher than the world acceptable value of 0.00013mSv/h (0.013mR/h ). All the radiological risk parameters estimated are relatively high. The result of this work shows that the mining µactivities have enhanced the radiation level of Ishiagu and health status of the populace.

Radiation dose risk variability and its implication in industrial and mining regions, NW Nigeria

The study area located in the southern part of Kebbi State, northwestern Nigeria, has witnessed intense mining activities and upscale industrialization in recent years. These events have necessitated deeper and insightful studies into radiological hazard evaluation to mitigate associated adverse consequences and enforce protective measures in the environment. A total of 45 sampled locations each were taken for both industrial and mining sites in northwestern Nigeria to determine the concentration of Potassium-40, Thorium-232 and Uranium-238 radionuclides as applied to radiological hazard analysis. The mean value of the absorbed dose in the industrial site was 90 nGy/h, whereas the mining site recorded a mean value of 210 nGy/h. Other radiological indices such as radium equivalent factor, external risk assessment, internal index and representative gamma index recorded mean values of 187.68, 0.507, 0.547 and 0.768 respectively, whereas the same hazard indices presented higher values of 412.58, 1.114, 1.231 and 1.675 respectively in the mining site. The variability studies showed that the dose risk ratio of the industrial region to the mining region is 1:2. The mining site presented radiological hazard indices higher than the recommended global threshold hence should be classified as a restricted zone to forestall health-related crises which may manifest among local dwellers.

Experimental research on the haulage drifts stability in steeply dipping seams

Purpose. Substantiation of the conditions for haulage drifts stability using different protection methods in steeply dipping seams based on a set of experimental studies. Methods. To achieve the purpose set, mine instrumental observations have been performed to study the rock pressure manifestations in zonal advance workings adjacent to the stope face on the haulage horizon. The conditions for their maintenance, within the mining site, are assessed by the side rocks convergence value on the drift contour and the change in the cross-sectional area, taking into account the deformation properties of the protective structures. Findings. It is recorded that in the zone of the stope works influence, in the most difficult conditions, haulage drifts are maintained, when coal pillars or clumps of prop stays are used for their protection. It has been determined that a decrease in the section of such mine workings up to 50% is the result of the protective structures destruction. When protecting the hau-lage drifts with the rolling-on chocks, a decrease in the mine working section up to 30% occurs in the process of the protective structures compression. It has been revealed that deformation of coal pillars or clumps of prop stays up to 10-20% leads to a loss of their stability, and an increase to 60% leads to a complete loss of their load-bearing capacity, intensification of rock displacements on the mine working contour and deterioration of its stability. It has been determined that in the process of deformation of the rolling-on chocks from sleepers by 20-60%, they are compressed without loss of load-bearing capacity, which ensures a smooth deflection of the overhanging stratum and restriction of rock displacements on the haulage drift contour. Originality. To study the deformation characteristics of protective structures above the drift, the function of the increment is used of side rock displacements on the haulage drift contour along the mining site length dependent on the relative deformations of protective structures, which makes it possible to assess the real dynamics of the process. Practical implications. When mining steep coal seams, using the specificity of geomechanical processes, which are manifested in an anisotropic coal-rock mass during unloading, satisfactory mine workings stability can be ensured by changing the deformation properties of protective structures above the drift.