RISET Geologi dan Pertambangan
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The origin of Baribis Fault and its relationship to the dynamics of Sunda Arc
Full text linkBased on analyses of published geological cross sections along the Baribis Fault, we briefly review several possible mechanisms of this backarc thrust that developed behind the volcanic arc in western Java. There is no general agreement regarding the mechanisms of the backarc thrust. Therefore, the origin of this fault remains uncertain. Previous works proposed that the backarc thrust in western Java may have developed as deformation of paleo-accretionary wedge sediments behind a continental backstop, inverted normal fault, northward migrating thrust belt, and thrusting due to gravitational sliding of the volcanic arc. However, evidences supporting those mechanisms still need to be elucidated. Detailed examination of the available geological data might suggest that backarc thrusting in western Java may have formed due to stress transfer through rigid arc blocks. The far-field stress from the subduction zone is propagated through remnants and modern volcanic arcs and finally, deformed sediments in the Bogor Trough that nucleated as backarc thrust
Reuse of feldspar ore waste after beneficiation for industrial use (Buzlukdaği / Kirşehir / Türkiye)
Full text linkFeldspar is the most widely used raw material in the ceramic and glass industries. The aim of this article is to investigate the possibility of using flotation process wastes from Buzlukdağı feldspar beneficiation plant as an alternative raw material. The scope of the study includes the evaluation of the use of wastes arising from feldspar enrichment and feldspar processes as alternative raw materials in another process and the investigation of their usability as a final product in various sectors and fields. As a first priority, the Fe2O3 content of the flotation concentrate was reduced to 0.4%. It has been made usable in the glass and ceramic industries. As a second priority, analysis of rare earth elements was made in the wastes formed after the flotation. According to the results of the experiments carried out on the wastes after flotation; demonstrated that it can be used for technological purposes. In addition, it has been determined that the wastes generated as a result of enrichment can be used to provide permeability in urban waste storage areas and hydroelectric dam constructions
Assessing the Water Criticality Index of the Welaran Watershed in Kebumen Geopark, Central Java: Towards Good Water Resource Management
Full text linkThe water criticality index (WCI) is the ratio between water use and availability. The higher the WCI value, the more concerned the water conditions in the area will be. The water crisis can be handled if various parties manage water resources following good management. The Welaran area is a watershed that is part of the Lukulo Watershed, where the population often experiences water shortages. Therefore, by knowing the value of WCI, it is hoped that various parties can know the water conditions in this watershed. Based on research and calculation of the water balance in the Welaran Watershed, it is known that with total water needs in 2019-2020 of 746,937 m3 and total water availability of 1,555,318 m3, the WCI value of the Welaran Watershed is 48.02%. In 2020, Karangsambung was designated as a part of Kebumen Global Geopark, which will certainly increase the number of tourists visiting here. The increase in tourist visits will also increase the need for water, including in the Welaran Watershed. To overcome these conditions, the Kebumen regency’s government and stakeholders are expected to be able to formulate a water management step by effective management
Open-Pit Coal Mine Drainage System Design at PT XYZ, Central Kalimantan
Full text linkABSTRACT
The purpose of implementing a mine drainage system is to ensure that mining activity areas are not flooded during the rainy season. The mine drainage system in this study consisted of designing sump dimensions, open channels, settling ponds, and pumping and piping systems. The planned rainfall is calculated using the maximum daily rainfall from 2003 to 2022, using the Log Pearson Type III method. The result of the calculation of the planned rainfall is 194.50 m/day. The total discharge of runoff water in the study area was 17.05 m3/s, and the volume of rain was 293,976.94 m3. The sump is designed based on KEPMEN ESDM 1827 K/30/MEM/2018 so that it can accommodate a volume of incoming water of 823,392.60 m3. The pumps used to remove water from the sump to the settling pond are six Multiflo 420 EXHV RPM 1550 pumps. The pipe used is polyethylene with the type HDPE PN 16 PP 100 and requires a length of 908.42 m. The pump capacity discharge is 1,255.40 m3/s with a total head loss of 138.89 m. The channel has discharge capacity of 2.40 m3/s. The settling pond consists of three compartments designed to accommodate a volume of 61,245.20 m3 of water.
ABSTRAK
PT XYZ merupakan perusahaan pertambangan batubara yang menerapkan metode open pit. Tujuan penerapan sistem penyaliran tambang yaitu agar daerah aktivitas penambangan tidak tergenang air ketika musim penghujan. Sistem penyaliran tambang pada penelitian ini terdiri dari perancangan dimensi kolam penampungan, paritan, kolam pengendapan, dan sistem pemompaan serta pemipaan. Curah hujan rencana dihitung menggunakan curah hujan harian maksimum mulai tahun 2003 hingga tahun 2022 menggunakan metode Log Pearson Type III. Hasil perhitungan curah hujan rencana sebesar 194,50 mm/hari. Total debit air limpasan di wilayah penelitian diperoleh sebesar 17,05 m3/detik dan volume hujan sebesar 293.976,94 m3. Kolam penampungan dirancang berdasarkan KEPMEN ESDM 1827 K/30/MEM/2018 tentang Pedoman Pelaksanaan Kaidah Teknik Pertambangan yang Baik, sehingga mampu menampung volume air masuk sebesar 823.392,60 m3. Pompa yang digunakan untuk mengeluarkan air dari dalam kolam penampungan menuju ke kolam pengendapan yaitu pompa Multiflo 420 EXHV RPM 1550 sebanyak 6 unit. Pipa yang digunakan adalah polietilen jenis HDPE PN 16 PP 100 dengan panjang 908,42 m. Debit kapasitas pompa sebesar 1.255,40 m3/detik dengan total julang yang diperoleh sebesar 138,89 m. Paritan memiliki kapasitas debit sebesar 2,40 m3/detik. Kolam pengendapan terdiri dari 3 kompartemen yang dirancang mampu menampung volume air sebesar 61.245,20 m3
FACIES ANALYSIS AND SEDIMENTATION MECHANISM OF VOLCANICLASTICS OF CIKARANG MEMBER OF JAMPANG FORMATION IN WEST JAVA
Full text linkThe Cikarang Member of Jampang Formation is one of basin fills of the Bogor Basin that is characterized by gravity flow deposits. The variations of lithologies with an abundance of volcaniclastics are found in the Tonjong River in Bojongkalong Village and indicate differences in facies and sedimentation mechanisms. We measured stratigraphy of the rock units supported by petrographic analysis and paleontological analysis. The rock units consist of 11 lithofacies: graded gravel (g1G), massive gravel (m1G), massive gravelly sand (mGyS), plane-stratified laminated sand-mud couplets (slSM), massive gravel-sand couplets (mGS), plane-stratified laminated to graded mud-sand couplets (slgMS), massive sand (mS), plane-stratified gravel-sand couplets (sGS), plane-stratified laminated muddy interval sand-mud couplets (sleSM), plane-stratified laminated muddy interval mud-sand couplets (sleMS), and slump and slide deposits gravel (sdG). The depositional environment of the Cikarang Member is inner-middle fan with changes in depositional sub-environment variations in the form of channels, sandy lobes, silty-sandy distal lobes, and proximal levees with constant paleobathymetry in the lower-middle bathymetry. The volcaniclastics of the Cikarang Member of Jampang Formation is deposited in a turbid mechanism due to a turbulent current with various cohesive debris flows (mudflows) and turbidity currents scattered in each facies association
ADAPTIVE PRECONDITIONING KRYLOV SUBSPACE METHODS FOR EFFICIENT NUMERICAL GROUNDWATER FLOW MODELING IN STEADY-STATE CONDITIONS
Full text linkThe numerical method plays an important role in groundwater flow modeling to solve linear equations with sparse matrices. This study evaluates the performance of the Krylov Subspace method with adaptive preconditioning compared to classical iterative methods, such as Gauss-Seidel, Jacobi, and Successive Over-Relaxation (SOR), in the simulation of steady-state groundwater flow on a 2D grid. The results show that the Krylov method with adaptive preconditioning provides the fastest execution time (0.0054 seconds) with minimal resource usage, such as CPU of 0.0% and RAM of only 0.175 MB. In contrast, the classic iterative method shows longer execution times and greater resource consumption. This study concludes that the Krylov Subspace method with adaptive preconditioning is the best solution for applications that require high efficiency in groundwater flow computin
Control of Sediment Grainsize on Lead (Pb) Content in the Reef Sediment Systems: A Case Study of Panjang Island, Banten Bay, Indonesia
Full text linkSediments are known to accumulate pollutants from terrestrial and coastal waters, and can be used as an indicator to monitor metal pollution in the biosphere and the effects of anthropogenic events in the environment. Eight samples of reef surface sediments were collected from the north and east coasts of Panjang Island. Panjang Island, located to the north of Banten Bay, was chosen for this study because of its proximity to many industrial areas. Nevertheless, the island supports a natural ecosystem, including coral reefs, seagrass, and mangroves. The samples were analyzed for the grainsize, component analysis, and Pb concentrationusing AAS flame method. The result indicated Pb concentration in the grain-supported surface sediment in Panjang Island is varied. The detected Pb concentrations were 0-28.68 mg/kg in dry weight. The study indicated that the different concentration of Pb value is mainly controlled by the different of sediment grainsize. The highest Pb accumulation occurs in the areas with very fine sediment grainsize, which have better adsorption capabilities for heavy metals. This study also suggests that the medium sand fraction may accumulate different Pb values. The result indicated that, according to the classification of ANZECC/ARMCANZ, all sediment samples in the study area is in the low risk of toxicant level. Additionally, the SQG-Q (Sediment Quality Guidelines) quotient analysis indicates that Pb concentration in the study area posed a low-moderate impact to adverse biological effect
Effect of bentonite on fly ash and bottom ash based engineered geopolymer composite
Full text linkFly ash, bottom ash, and bentonite have potential to be used as geopolymer precursors, because they contain high silica and alumina. Until now there has been no research that combines these three materials as geopolymer materials. This research aims to incorporate bentonite as an aluminosilicate source in the fly ash and bottom ash based geopolymer. Geopolymer concrete was made by mixing precursors, alkaline activator, aggregate (gravel), superplasticizer, and water. The characterization of geopolymer concrete was carried out using XRD, XRF, and SEM-EDS. Then the compressive strength test was carried out. The SEM-EDS results show that the elements contained in geopolymer concrete are dominated by Si, Al, and O. The XRF results, the constituent compounds of geopolymer concrete are dominated by silica and alumina compounds. The XRD phase results formed are Quartz, Albite, and Hematite. The sample with code K6, which did not contain bentonite, had the highest compressive strength value of 9.57 MPa and 8.92 MPa at a drying time of 18 hours and 24 hours, respectively. This can happen because the addition of bentonite can reduce the retraction process. This also causes the porosity of the concrete to increase, thereby reducing its compressive strength.