RISET Geologi dan Pertambangan
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A Review of Synthetic and Earth's Resource-Based Slow-Release Fertilizers and Their Potential Role in Reducing Groundwater Pollution
Full text linkGroundwater is an essential water source for humans. Unfortunately, some groundwater resources have been contaminated by wastes from various sectors. Fertilizer also contributes to groundwater contamination. The nutrients from fertilizer that are not absorbed by the plant move towards groundwater reservoirs and contaminate the groundwater. Slow-release fertilizer is a solution to reduce groundwater pollution while maintaining fertilizer’s function as the sources of nutrients for plants. This paper discusses and reviews the relevant literatures related to groundwater, fertilizer, slow-release fertilizer, and earth’s based slow-release fertilizer. The release rate of nutrient elements from different types of fertilizer is also presented. The synthetic base slow-release fertilizers and earth’s resource-based slow-release fertilizers can hold nutrients longer than conventional chemical fertilizers when exposed to water. Two particular minerals that can be used as raw materials in slow-release fertilizer synthesis are analyzed using XRD. They are from hydrothermal silica and obsidian. The XRD analysis of hydrothermal silica and obsidian shows the presence of amorphous silica and other minerals. Silica in compacted slow-release fertilizer can control the release rate of nutrient elements from fertilizer.
Dewatering requirements assessment for the Central Kalimantan NCP open pit gold mine
Full text linkOne of the most critical aspects of open pit mining is the dewatering and mine drainage systems. The NCP Open Pit Gold Mine is located in Central Kalimantan. This study area has a range of rainfall intensities and durations from moderate to heavy. Good dewatering is required to manage runoff water and reduce runoff from entering the pit and mine front loading. The study used daily rainfall intensity data from 1994 to 2018. Using the Mononobe Method, the hydrological data for this area were evaluated by determining the value of the rainfall intensity plan. According to the evaluation of rainfall data from 1994 to 2018, the research area saw a rainfall intensity of 86.23 mm/day over a two-year return period. The majority of water extracted from mines is from precipitation and runoff rather than groundwater. An open channel was made around the open pit, flowing water naturally into the sump to reduce water entering the mining area. The water was pumped into the settling pond with 520 m3/hour and 780 m3/hour capacity pumps
Modeling of individual debris flows based on DEMNAS using Flow-R: A case study in Sigi, Central Sulawesi
Full text linkOn 2018 September 28, 18:03 a local time (10:03 am UTC), the Mw 7.5 earthquake with a focal depth of about 20 km devastated the Palu region in Central Sulawesi, Indonesia resulting in a catastrophic disaster and many casualties. The Palu earthquakes triggered widespread landslides upstream, contributing to the sizeable material volume accumulated in rivers and mountain slopes. After the Palu earthquake, from September 28, 2018, until December 2021, at least 24 events of debris floods have occurred, which have spread to 15 villages. As of late, the empirical debris flow model Flow-R, software for susceptibility mapping of debris flows at a regional scale, was published. While Flow-R's applicability on a regional scale has been confirmed in several studies, the calibrated case using back-analysis of individual debris flow events in Indonesia based on DEMNAS with a spatial resolution of 8.3 m has never been conducted. Local debris flows modeling using Flow-R was evaluated with three well-documented debris flow events on the break slopes on the west and east sides of the Palu Valley. Quantitative analysis was carried out in this study to assess the accuracy, positive predictive value, and negative predictive value of models. First, the result shows the individual back-analysis model of debris flows found good agreement between debris-flow paths predicted and documented debris flow path extent. However, the parameters for rheological properties and erosion rate required in the software are limited. Second, the quantitative analysis shows accuracy, positive, and negative predictive value, which varies considerably. Based on the study, Flow-R is not suitable for comprehensive hazard mapping but provides a direct information about possible run-outdebris flow paths. Furthermore, lateral spreading and friction of Flow-R model results can be used to calibrate the process with rheological properties and erosion rate in other numerical modeling software, either for forward or back analysis
Site selection for artificial recharge in Cisangkuy sub-watershed, West Java, using combined fuzzy logic and genetic algorithm
Full text linkThe Cisangkuy sub-watershed is part of the Citarum watershed with ±300 km of river length. The total area is in line with the potential of water resources which is quite good, but over time the hydrological condition of the site has decreased. Decreasing the hydrological state is due to changes in land use and land cover from year to year and is indicated by high discharge and flooding in the rainy season. This study aims to find the optimal location of artificial recharge to maintain water balance in the Cisangkuy sub-watershed. Fuzzy logic is used for determining the location of artificial recharge by considering the input variable DRASTIC in the form of depth to groundwater level, net recharge, aquifer media, soil type, slope, vadose zone, and hydraulic conductivity. In addition, subtractive clustering is performed to obtain the class of each DRASTIC parameter. Furthermore, a genetic algorithm is carried out to get the optimal location of the artificial recharge zone. The priority zone is indicated by the high class of each DRASTIC parameter input. Combined fuzzy logic and genetic algorithm show that the optimal location for artificial recharge is in the northern part of the Cisangkuy sub-watershed, precisely in the Banjaran area
Land subsidence hazard in Indonesia: Present research and challenges ahead
Full text linkLand subsidence has become a significant silent hazard in the big cities across Indonesia that aggravates future sustainable development. Land subsidence hazards hard-hit Java as the most densely populated island. This paper reviews Indonesia’s land subsidence hazards, particularly subsidence cases across the big cities on Java Island, Jakarta, Semarang, and Bandung. Generally, land subsidence research in Indonesia can be categorized into two broad focuses: monitoring subsidence rate and investigating land subsidence mechanism. This paper aims to present a comprehensive summary of the current status of land subsidence research in Indonesia and discusses the challenging issues encountered in research and mitigation measures. A qualitative literature review was used in this study for reviewed articles in the Google Scholar database published in Indonesian and English up to 2020. Land subsidence in Jakarta, Bandung, and Semarang is still ongoing at a high rate. Its mechanism is highly influenced by excessive groundwater withdrawal, although other natural and anthropogenic factors also play a part. This review proposes recommendations to alleviate the impacts of land subsidence hazards in Indonesia and for further researc
Characterization of Thorium-bearing Minerals Using Micro-XRF in Metamorphic Rocks of Harau, West Sumatera
Full text linkIn 1974, BATAN conducted a survey to review the potential of radioactive minerals in Harau, West Sumatra. The survey shows that there are radiometric anomalies in several locations in the area. However, the survey has not been able to show the radioactive elements and minerals found in Harau. This study aims to identify and characterize radioactive elements and minerals in Harau. To prove that detailed geological mapping, radiometric mapping with Gamma Spectrometer RS-125, and analysis using Micro-XRF "M4 Tornado Plus®". The results of geological and radiometric mapping show that there are high thorium contents in the metamorphic rocks of the Kuantan Formation reaching 2300 ppm eTh. Identification of thorium-bearing minerals using a micro-XRF instrument resulted in thorium-bearing minerals found in the Harau area are thorite (ThSiO4), yttrialite (YThSi2O7), and monazite ((Ce,Nd,Th)PO4) with thorium levels within 2.75 - 42.75% ThO2 but experiencing a significant increase in Fe. In principle, micro-XRF analysis can identify minerals well, but this analysis can be supported by other analyzes so that it can provide much more precise results. This research is expected to provide information about the occurrences of thorium-bearing minerals in Harau, West Sumatera
Kinetics Study of Leaching Ore Nickel Laterite Using Hydrochloric Acid in Atmosphere Pressure
Full text linkLeaching of nickel laterite ore at atmospheric pressure is a leaching method that can be operated at >100⁰C temperatures in an atmospheric pressure, which is applicable to a low-grade laterite ore. This research aimed to study the effect of temperature, acid concentration, and leaching time on nickel extraction percentage and the leaching kinetics. Hydrochloric acid (HCl) was used as a leaching agent and several variables were applied, i.e., temperature (80⁰C, 90⁰C, 100⁰C), HCL concentration (5 M, 6 M, 7 M), and leaching duration (120 minutes, 150 minutes, 180 minutes) to investigate their effect on nickel extraction percentage. In addition, the kinetics of the leaching process was studied using a Shrinking Core Model. The results showed that the percentage of nickel extraction increased with increasing temperature, HCl concentration, and leaching time. The lowest percentage of nickel extraction of 51.29% was obtained when 80⁰C, five molar HCl, and 120 minutes leaching duration were applied. In contrast, The highest percentage of nickel extraction of 97.22% was obtained at 100⁰C, seven molar HCl, and 180 minutes of leaching time. The kinetics study results show that diffusion through the unreacted solid product layer controls the nickel leaching rate.Leaching of nickel laterite ore at atmospheric pressure is a leaching method that can be operated at >100⁰C temperatures in an atmospheric pressure, which is applicable to a low-grade laterite ore. This research aimed to study the effect of temperature, acid concentration, and leaching time on nickel extraction percentage and the leaching kinetics. Hydrochloric acid (HCl) was used as a leaching agent and several variables were applied, i.e., temperature (80⁰C, 90⁰C, 100⁰C), HCL concentration (5 M, 6 M, 7 M), and leaching duration (120 minutes, 150 minutes, 180 minutes) to investigate their effect on nickel extraction percentage. In addition, the kinetics of the leaching process was studied using a Shrinking Core Model. The results showed that the percentage of nickel extraction increased with increasing temperature, HCl concentration, and leaching time. The lowest percentage of nickel extraction of 51.29% was obtained when 80⁰C, five molar HCl, and 120 minutes leaching duration were applied. In contrast, The highest percentage of nickel extraction of 97.22% was obtained at 100⁰C, seven molar HCl, and 180 minutes of leaching time. The kinetics study results show that diffusion through the unreacted solid product layer controls the nickel leaching rate
Ichnofossils Characteristics in Pelagic Siliciclastic Carbonate Turbidites of Weda Formation, Halmahera Island
No full textThe Weda Formation in Lili River, Dorosagu, East Halmahera consists of siliciclastic and pelagic carbonates deposited in a submarine fan environment. Research on the Weda Formation in the northern part of Halmahera Island is relatively minimal because most of the research about this formation has been carried out in the southern part of Halmahera Island. The lack of road access and its remote location have resulted in the lack of intensive research on this formation. This study aims to determine the relationship between the intensity and diversity of trace fossils in the submarine fan facies association of the Weda Formation. Sedimentological studies include sedimentary texture, sedimentary structure, turbidite material type, and layer thickness. While the study of trace fossils includes the identification of trace fossil types, classification of behavior, intensity, and diversity in sedimentary layers, and the factors that influence them during deposition. There are eight types of ichnofossil observed in the Lili River, Ophiomorpha, Thalassinoides, Rhizocorallium, Palaeophycus, Zoophycos, Chondrites, Lorenzinia, and Spirorhaphe, which are found in three facies associations (AF): submarine fan channel facies association (AF1), submarine fan lobe facies association (AF2), and submarine fan distal facies association (FA3). The submarine fan channel facies is characterized by the presence of Ophiomorpha and Thalassinoides which present in low intensity and low diversity due to unstable environmental conditions-high stress due to intensive turbidite currents. The submarine fan lobe facies shows a higher density and diversity where ichnofossil is classified into two based on the substrate in the flysch deposits. Rhizocorallium, Thalassinoides, and Palaeophycus ichnofossil were formed in the sand substrate, while Zoophycos and Chondrites ichnofossil were formed in the shale substrate. Palaeophycus, Zoophycos, Chondrites, Lorenzinia, and Spirorhaphe ichnofossil were found in the submarine fan distal facies associated with high intensity indicating low energy levels and low sedimentation rates
Investigation of paleochannel identification using radar and optical images on placer deposits in Bangka Barat Regency, Indonesia
Full text linkThis article is about a visual investigation of paleochannel identification using ALOS 2 PALSAR 2 (Advanced Land Observing Satellite 2 Phased Array type L-band Synthetic Aperture Radar 2) radar satellite image. The radar image has a higher layer-penetration ability than the optical image so that the characteristics of near-surface materials are possible to be detected, including the morphology of the abandoned river stream. The purpose of ancient channels investigation is to localize potential areas of tin placer deposits, including rare earth elements as associated minerals. This investigation was aided by LANDSAT 8 optical image and National Digital Elevation Model (DEMNAS) data. Visual identification has been performed based on the shape, color, pattern, texture, and position against other morphologies in the image. The criteria for paleochannels are the channels detected using ALOS 2 PALSAR 2 image but not in LANDSAT 8 optical image and DEMNAS data. Based on these criteria, eleven traces of paleochannels have been well identified. Their occurrences are generally associated with meanders, open areas, and near the coast. The detected paleochannels are generally purple to dark in the color composite of the ALOS 2 PALSAR 2 image. These detected rivers are in pink to purplish-green zones and have a random appearance