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Inquiring the flyrock to determine minimum safe distance of coal overburden blasting against residential area

Fly rock is a rock fragmentation that is thrown as a result of blasting. Such fragmentation that is thrown beyond the specified safe distance can cause a damage to the infrastructure, mechanical equipment and humans. This study aims to determine the safe radius of the fly rock that resulting from blasting residential area which that has a distance 200-300 m and has potentially distressing to cause damage. Calculating of the flying rock throwing distance is carried out theoretically and actually with orientation to the distance between spaces, the distance between burdens, minimum stemming height, minimum hole depth, powder factor, average charge blast hole and distance initial burdens. For theoretical calculations, the save distance is calculated by empirical methods and dimensional analysis. Results of the study shows that the maximum distance of the actual fly rock throw is 05.31 m and based on the predictions using the Cratering Method, the maximum distance of fly rocks is 172 m with a safety factor of 2 and the maximum distance of fly rocks is 199.04 m with a safety factor of 2. Based on the actual and predicted data above, it is not safe for blasting locations that is less than 200 m from residential areas, that refers to the safe radius threshold based on the regulation of the Minister of Energy and Mineral Resources No. 1827 K/30/MEM/2018.

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Study of supply-demand of Indonesia buton asphalt

National asphalt that was needed around 1.2 million tons per year are fulfilled by Pertamina's oil asphalt production around 272,040 tons (22.27%). Such a production is related to US$283.77 million, Indonesian natural asphalt (Asbuton) from Buton around 21,226 tons (1.74%) that is worth US$9.13 million. Its shortfall was met by the an import of 945,180 tons (77.39%) that is worth of US$473.77 million. The Asbuton resources are enormous around 792.5 million tons and its reserve is approximately 182.65 million tons. There are 16 Asbuton processing factories with the total capacity of roughly 2.03 million tons per year. However, their production is still 43,128 tons per year. It means the production utility is only 2.1% of the total production capacity. This study aims to optimize the use of Asbuton. Secondary data is obtained from various agencies, official websites, research reports, journals, and sharing sessions. Data analysis using an econometric model with a simple linear regression equation. The results show that the import substitution program starts in 2023, where the national asphalt needs are 935,180 tons, and its production is 253,473 tons and its import substitution in the first year is gradually around 96,061 tons, which means that the will be 585,647 tons so that the country can save foreign exchange of US $ 65.66 million. In 2031, substitution has exceeded the imports number, result and the excess capacity, thus opening up the export opportunities of 96,060 tons. Referring to such condition, the country can get additional income around US$656.59 million. This situation will continue until the end of the projection year in 2045.

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Application of induced polarization (ip) method for identifying metallic mineral distribution in the Leon area

The research was conducted in the Leon area to determine the presence and quantity of metallic mineral resources. The stratigraphy of the study area is composed of alluvium and coastal deposits, Molasa Sarasin Formation, Tinombo Formation, and Intrusion. Exploration was carried out in the Leon area using Induced Polarization Method with a dipole-dipole configuration with an area of ​​950 m2. The length of the track is 580 meters with a North-South orientation. The number of tracks in this study was 15, with spacing electrodes as far as 20 meters and n = 1-10. The analysis showed that the distribution of resistivity values ​​in the study area was from (13.6 to 1337) Ωm, while the chargeability values ​​had a range of values ​​(1.7 to 50.6) ms. The low resistivity values ​​below 50 Ωm are interpreted as claystone to sandstone and the medium resistivity values ​​between 50 Ωm - 500 Ωm are interpreted as compact sandstone to breccia. The resistivity values ​​above 500 Ωm are interpreted as igneous rock. The presence of metallic minerals in the study area is characterized by changeability values ​​above 22 ms in claystone, sandstone, breccia, and igneous rock. Calculating hypothetical resources was conducted the Block model method at Oasis Montaj that obtained 11.8 million tons of resources.

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Evaluation of rock slope using q-slope, limit equilibrium and failure probability at andesite mine of Sidomulyo Village

For an open pit mine, the rock slope stability is one of the major significant challenges at every stage in the operation. It became a concern from the planning until the mining closure. Mining activities in the research location have entered the mining closure phase and produced the final slope that consists of 4 single slopes with an overall slope height of 65m and an angle of 62° that its stability is not yet known. The actual overall slope has discontinuities which affect the potential for failure. Most of the methods used in geotechnical practice for estimating slope stability are based on the traditional limit equilibrium methods. On the other side, very few empirical techniques exist to assess the slope stability. The empirical method of the Q-Slope is a relatively new methodology for assessing the slope stability in terrains built from rock masses. This method was developed over the last decade by Barton and Bar (2015), with modifications to the original Q-System for application in rock slope stability through the parameter of RQD, Jn, Jr, Ja, O-Factor, Jwice, SRFa, SRFb and SRFc. The stability analysis by Q-Slope method has resulted the slope in stable condition because the value of βQ-Slope > βSlope. The factor of safety limit equilibrium method and probability of failure used the actual geometry and Q-Slope geometry is known in stable condition because it fulfils acceptance criteria with FoS ≥ 1.1 and PoF ≤ 37,5% according to the regulation Ministry of Energy and Mineral Resources Decree 1827/K/30/MEM/2018.

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Techno-economic of graphite anode recycling process of electric vehicle lithium-ion batteries

Graphite is the primary material for battery anodes used in electronic devices such as cell phones, laptops, and electric vehicles. Exploiting natural graphite in Indonesia is still in the exploration stage. The ever increasing demand for energy storage devices poses challenges in producing battery-grade graphite. One possible approach is to recycle the graphite anode (AG) from used Lithium-ion Batteries (LIB) into battery components. By utilizing waste as a raw material, production costs are lower as well as the use of LIB becomes more sustainable. This study discusses the techno-economics of AG recycling from electric vehicle (EV) LIBs. Secondary data is used from various research reports, journals, and books published through the official website as references and assumptions in calculations and analysis. Mechanical separation to remove plastic components, washing with organic solvents (using dimethyl carbonate-DMC) and using dimethyl carbonate (DMC) and N-methyl-2-pyrrolidone (NMP), then washing process with H2SO4 + H2O2 purifies graphite to be reused as anode material for the new LIB. Economic analysis shows that the Net Present Value is IDR 388,675,699, the Internal Rate of Return is 33.79% per year, and the Payback Period is two years and ten months. These three indicators show that the project is financially viable. The sensitivity analysis shows that it is still profitable if there is an increase in production costs of up to 20% and a decrease in selling prices of up to 20% or USD 12,000 per tonne.

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Exploration of indigenous arbuscular mycorrhizal fungi on Arenga pinnata Merr in post-mining land

Mining activities have a positive impact that can generate income for the state, but the activities also cause negative impacts in the form of soil damage, vegetation and animal losses to disrupt the ecosystems. Therefore, it is necessary to carry out a reclamation with revegetation using local plant species. PT Berau Coal has conducted revegetation using a local sugar palm plant (Arenga pinnata). The success of sugar palm plant growth in post-mining reclamation land is influenced by several factors, one of it is the symbiosis of the arbuscula mycorrhizal fungi (AMF) with the sugar palm planted by PT Berau Coal. The purpose of this study was to determine the diversity of indigenous spores in the arenga rhizosphere and root colonization of sugar palm plants. Identification of the AMF diversity was carried out by observing the soil taken from the palm rhizosphere with a depth of 0-20 cm and 20-40 cm. Isolation of spores using the wet pouring technique method with centrifuges and AMF spores were identified using the INVAM methods. The observation of AMF colonization on plant roots was carried out through the root staining technique with the Clapp modification method. The results showed that the AMF spores were found in 3 AMF genera at the observation site, namely genus Glomus (15 sp), Acaulospora (3 sp), and Gigaspora (1 sp). The highest spore abundance is genus Glomus sp at a soil depth of 0-20 cm. The AMF structures found colonizing the roots of sugar palm plants are hyphae, vesicles, and spores.

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