Coal production target in East extension of TAL Limoa Front was 180.000 ton/month in October2015 but the target achieved only 115.967,59 ton with the percentage achievement of productiontarget at 64,4 %. Therefore it was necessary to evaluate performance of Dozer Ripper D375 numberseries DZ 521. The evaluation conducted by taking primer actual data in mine site such as cycletime, work distance, work effeciency, Ripper penetration and then the collecting data was processedto make reparations of DZ 521 type of D375 Ripper with the aim to meet the production target. Theachieved production after prior evaluation conducted by increasing work time effeciency was162.826,57 ton with the production achievement percentage at 90.45 % and the lack production was17.173,43 ton, a further evaluation was conducted by repairing of Ripper penetration performance andthe production was 206.138,22 ton with the production achievement percentage at 114% and theexceed production was 26138,22 ton. Then work time efficiency and Ripper penetration was improvedto obtain target production of 289.475,83 ton with the production achievement percentage at 160%and exceed production of 109.475,83 ton with time reserve 150 hours/month and 4,8 hours/daymaybe can back up the problems on location production. The evaluation had been met coalproduction target of Limoa Front.
The work efficiency value on the TB Pemali mining front in 2018 is relatively low (57.16%), This condition means it required the improvement of the work efficiency in accordance with the good mining practice. Method used in this research including preparation, collecting data and field orientation, which is then processed as follows: counting work efficiency of the dig tools for load and hauling tools in mining area front, analyzing operator performance and equipments conditions in mining area front, and analyzing work efficiency improvements. The result showing that score of current work efficiency of the dig tools for load in the amount of 62.74%, and for hauling tools in the amount of 57.68%. This result shows that low score of work efficiency in mining area front caused by large breakdown time of the hauling tools and low performance of the operator, then improvement of work efficiency is carried out by reducing the operator's variable trouble limit by 35% and reducing indent time of broke sparepart, the final score of work efficiency of the dig tools for load in mining area front is in the amount of 66.27% and for hauling tools in the amount of 66.44%
Industrial-scale Magnetic Separator is used to process tin ore by separating magnetic and nonmagnetic minerals using a belt conveyor speed and splitter opening only one variation. Based on this, this research is intended to obtain a more varied and optimal combination of variable settings in the recovery of tin ore yields. The method used is quantitative data analysis method by obtaining nonmagnetic minerals using a combination of splitter openings and belt conveyor speed based on grain size, calculating the content of tin ore in non-magnetic minerals using the Grain Counting Analysis method and calculating the composition of tin ore recovery. The research was conducted based on grain sizes of 60 mesh, 80 mesh, and 120 mesh using a combination of splitter opening sizes of 0.2 cm, 0.4 cm, and 0.6 cm and using a belt conveyor speed of 27.12 cm/s, 28.15 cm/s, and 28.40 cm/s. The sample used for each grain size is 9,000 grams with repetition for each combination of variables, namely 30 times. The results of this study obtained the highest yield of tin ore at grain size of 80 mesh as much as 1,753.7 grams in 8,920.3 grams of non-magnetic minerals with tin ore grades of 19.66% using a combination of speed 27.12 cm/s and splitter opening 0.2 cm. Based on the results of the study, the tin ore contained in the non-magnetic material processed by the Magnetic Separator, the grain size of 80 mesh is higher than that contained in the grain size of 60 mesh, while the grain size is finer than 80 mesh, the lower the recovery of tin ore contained in the non-magnetic material. Meanwhile, the larger the splitter opening and the speed of the conveyor belt, the higher the nonmagnetic minerals obtained.
Tin ore mining activities in Front 2 of 2.2 Tempilang Large Mine was operated by business partnerof PT Timah (Persero) Tbk, PT Bahtera Sarindo Utama used Open Pit Mining Method with mechanicalsystems. Open Pit Mining Method would eventually form a large basin, so that would become a placefor air accumulation at the base of mine site, applied drainage system used Repressive KuruativeDrainage System by allowing water to pour into the mine and then concentrated on the front sump andthey would be removed from the mine using pumping systems. Rainfall data used included amaximum rainfall data with period of 2005-2014, the calculation of rainfall plans used Gumbeldistribution and calculation of rainfall intensity with Mononobe Equation, but for the period of rain istaken with the 2-year period. From the research, the existing sump had capability to retain water with avolume of 79.5 m3 and existing pumps had the capacity of 86.4 m3/h, while the total water poured inthe mine was 2172.588 m3/day with total of catchman area was 64085.442 m2. To improve drainagesystem performance on Front 2 of 2.2 Tempilang Large Mine, dimensional sump need to be repairedwith a capacity of 1267.336 m3 to bring outwater volume plan outside of work time (14 hours) and analternative pump was add 1 unit of recommendation pump with the same type such as Mitshubisi6D16 gravel pump (engine) with a pump capacity of 154.8 m3/h, but the actual pump was still beingused so that with the use of two unit pump acquired total pump capacity was 241.2 m3/h with thelifetime of pumping was 9 hours to remove the water 2172.588 m3/per day.
Pangkalpinang city is one part of Bangka Belitung Archipelago Province which has an area of 118.41 km2 with seven districts and consist of forty-two villages. Based on its location on the eastern part of bangka island make pangkalpinang closer to the coast and watersheds so that it can be said it have a relatively low average land elevation (topography) with a height of 20-50 meters above the sea with a slope of 0-25 %. The research was carried out quantitatively and qualitatively with the parameters of determining the administrative boundaries of each district, the selection of applicable rules regarding the applicable land use zoning or spatial planning (RT/RW), topography, surrounding watersheds, and population density of settlements in Pangkalpinang City. These parameters are then carried out using overlay, scoring and layout techniques to see the distribution of the flood vulnerability level pattern. The results showed that flood vulnerability (very vulnerable) with low topography (0-10 meters above sea level) was in the northwest area of Bukit Intan District and Taman Sari District. Flood vulnerability (vulnerable to less vulnerable) with moderate topographic values (10-19 meters above sea level) is in Gerunggang and Gabek Districts, while vulnerability is not vulnerable with high average topographic values (above 20 meters above sea level). in the northern part in the Districts of Gerunggang, Gabek, and Pangkalbalam. In the northwest part of Pangkalpinang City, if there is an increase in tides or high rainfall intensity, the area will be inundated (flooded).
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