Acid mine drainage (AMD) is formed due to the oxidation of sulfide minerals in the presence of water and air. AMD already entering the environment can damage the aquatic ecosystem due to low pH and high dissolved metal concentrations. Efforts to prevent the formation of AMD are by regulating the stockpiling of materials containing sulfide or potential acid forming (PAF) with non-acid forming (NAF) to avoid oxidation reactions of sulfide minerals. The purpose of this study was to simulate the effect of adding fly ash ratio as a PAF rock coating material to the quality characteristics of leachate using the laboratory-scale free draining column leach test (FDCLT) method. Adding fly ash ratio as a layering material significantly affects the quality of the resulting leachate. This is due to the physical condition of the fly ash material, which cannot prevent the meeting of AMD-forming components.

Southern Sumatra and its surroundings are close to the contact zone of the Indo-Australian plate and Eurasian plate, so the area always relates to the high seismicity zone. The Sumatran subduction zone, the Mentawai fault, and several segments of the Sumatran fault drive seismic activities in the area. Tectonic settings are essential to understanding the area's source and hazard. This understanding can be obtained using the relocated hypocenter distribution and the 3D velocity model in the area. Relocated hypocenters and velocity models are obtained from simultaneous inversion from the BMKG earthquake catalog in January 2012-December 2020 using the double difference seismic tomography method. Seismic velocity inversion of P- and S- wave tomograms image the thermal zone beneath Dempo and Patah volcanoes at a depth of 30-50 km. Slab dehydration is also observed in several forearc high zone. Both phenomena are associated with negative anomalies. The Sumatran and Mentawai fault zones are marked between negative and positive anomalies on the contact zone. The subducted slab of the Indo-Australian plate is observed until a depth of 150 km, which is the maximum depth of nodes used in this study. The granitic basement beneath Anak Krakatau volcano is detected until 10 km. Two of those geological features are related to positive anomalies.

ABSTRAK Provinsi Nusa Tenggara Barat (NTB) merupakan daerah dengan aktivitas kegempaan yang tinggi. Fenomena ini disebabkan oleh adanya aktivitas tektonik sebagai akibat pertemuan Lempeng Eurasia-Australia (zona subduksi) di bagian selatan dan Sesar Flores di bagian utara serta adanya keberadaan sesar-sesar lokal. Terkait dengan rencana pengembangan kawasan Samota di Pulau Sumbawa, NTB, perlu dilakukan suatu kajian kegempaan. Tujuan penelitian ini adalah memetakan indeks kerentanan seismik (Kg) melalui pengukuran mikrotremor dengan analisis menggunakan metode Horizontal to Vertical Spectral Ratio (HVSR). Hasil penelitian berupa peta kerentanan seismik daerah Plampang yang menunjukkan bahwa sisi utara lokasi penelitian memiliki indeks kerentanan seismik rendah yang ditandai dengan nilai amplifikasi kurang dari tiga jika dibandingkan daerah lainnya. Geologi sisi utara lokasi penelitian tersusun oleh batuan gunung api dengan karakteristik batuan keras, ketebalan sedimen sangat tipis, dan tersusun atas batuan Tersier atau lebih tua. Peta kerentanan seismik berguna sebagai acuan dalam mitigasi gempa bumi untuk mengurangi risiko yang ditimbulkan. ABSTRACT Nusa Tenggara Barat (NTB) Province is an area with intense seismic activity. This phenomenon is caused by tectonic activity as the result of the convergency of the Eurasia-Australia Plates (subduction zone) in the south and the Flores Fault in the north as well as the presence of local faults. Regarding the plan to develop the Samota area in Sumbawa Island, NTB, a study concerning earthquakes should be done. The purpose of this study is to map the seismic vulnerability index (Kg) through microtremor measurement by using the Horizontal to Vertical Spectral Ratio (HVSR) analysis method. The result of the study is a seismic vulnerability map of the Plampang area which its northern part has a low seismic vulnerability index indicated by the amplification factor value of less than three compared to other areas. The geology of the northern part of the Plampang area consists of volcanic rocks which has hard rock characteristic, very thin sediment thickness, and composed of Tertiary or older rocks. Seismic vulnerability maps can be useful as a reference for earthquake mitigation to reduce its risks.

ABSTRAK Kajian risiko pajanan radiasi gama dan gas radon dilakukan di area terowongan eksplorasi uranium dalam upaya melindungi pekerja dari bahaya radiasi pengion di tempat kerja. Pengukuran pajanan sinar gama dan konsentrasi gas radon dilakukan di dalam terowongan eksplorasi uranium Remaja dan sekitar kamp pekerja di daerah Kalan, Kalimantan Barat. Pajanan sinar gama diukur menggunakan surveimeter gama, sementara pajanan radon (222Rn/220Rn) menggunakan detektor pasif RADUET. Konsentrasi gas radon dan toron di dalam terowongan secara umum cukup tinggi, berkisar antara 188,84 hingga 495,86 Bq/m3 (rata-rata 375,80 Bq/m3) sementara toron berkisar antara 58,07 hingga 340,73 Bq/m3 (rata-rata 189,80 Bq/m3). Nilai tersebut berada di atas reference level radon (300 Bq/m3) yang disaranakan oleh International Commission on Radiation Protection (ICRP). Dosis efektif tahunan sinar gama mencapai nilai 147,88 mSv di dalam terowongan eksplorasi. Nilai tersebut berada di atas nilai batas dosis untuk pekerja, yaitu 20 mSv. Pengendalian pajanan sangat penting dilakukan dengan memenuhi prinsip “as low as reasonably achievable” (ALARA) dan proteksi radiasi eksterna untuk melindungi pekerja di dalam terowongan dari masalah kesehatan yang disebabkan oleh pajanan dari sinar gama, radon, dan toron.ABSTRACT A risk assessment of gamma radiation and radon gas exposure is carried out in the uranium exploration tunnel area to protect workers from the ionizing radiation hazards in the workplace. Measurement of gamma-ray exposure and radon gas concentrations were carried out in Remaja uranium exploration tunnel and around the workers camp in Kalan Area, West Kalimantan. Gamma exposure was measured using a gamma survey meter while radon (222Rn/220Rn) using RADUET passive detector. The concentrations of radon and thoron gas inside the tunnel generally are high, ranging from 188.84 to 495.86 Bq/m3 (375.80 Bq/m3 average) and 58.07 to 340.73 Bq/m3 (189.80 Bq/m3 average) respectively. These values are above the radon reference level (300 Bq/m3)which is recommended by the International Commission on Radiation Protection (ICRP). The annual gamma effective dose reaches 147.88mSv inside the tunnel. This value is exceeding the 20 mSv dose limit value for workers. It is necessary to control the exposure by fulfilled the principle of “as low as reasonably achievable” (ALARA) and external radiation protection to secure workers inside the tunnel from a health issue caused by gamma-ray, radon, and thoron exposures.

ABSTRAK Relokasi hiposenter merupakan suatu metode yang digunakan untuk mendapatkan parameter-parameter gempa yang presisi. Parameter-parameter tersebut digunakan untuk studi tektonik lanjut seperti seismic hazard assessment pada suatu area. Penggunan model kecepatan 3-D secara teori akan memberikan hasil yang lebih baik dibandingkan dengan model 1-D karena model kecepatan di bawah permukaan bumi lebih mendekati model 3-D. Sebanyak 767 event gempa yang direkam oleh jaringan seismik DOMERAPI, MERAMEX, BMKG, dan BPPTKG digunakan pada penelitian ini. Gempa-gempa tersebut direlokasi dengan model kecepatan 3-D dan dianalisis untuk studi seismotektonik di wilayah Jawa Tengah dan sekitarnya. Hasil relokasi hiposenter menggunakan model kecepatan 3-D berhasil mendeteksi sejumlah fitur tektonik secara lebih jelas seperti struktur kolom yang berkaitan dengan Struktur backthrust di selatan Kebumen. Penampang vertikal arah barat-timur yang melewati Sesar Opak mengindikasikan arah dip bidang sesarnya ke arah timur. Zona seismik ganda yang terdeteksi pada studi sebelumnya tidak bisa teridentifikasi dengan baik pada studi ini. Sejumlah gempa volcano-tectonic (VT) berkaitan dengan aktivitas magma dangkal Gunung Merapi terdeteksi juga dengan jelas pada studi ini.ABSTRACT Hypocenter relocation is a method used to get precise earthquake parameters. They will be useful for an advanced tectonic study like seismic hazard assessment in an area. The hypocenter relocation using a 3-D velocity model will theoretically obtain better results than a 1-D velocity model because the earth subsurface model is closed with a 3-D model. Some 767 earthquakes recorded by DOMERAPI, MERAMEX, BMKG, and BPPTKG networks used in this research. They were relocated by using a 3-D velocity model and analyzed for seismotectonic study in Central Java area and its surroundings. The result of hypocenter relocation using a 3-D velocity model is successfully detecting some tectonic features more clearly like columnar structure related to the backthrust structure at the south of Kebumen. The west-east vertical cross-section crossing the Opak fault indicates the dip of the fault plane is directing to the east. This study could not identify the double seismic zone, which was detected by the previous research. Some volcano-tectonic (VT) earthquakes related to the shallow magma activity of Mount Merapi also are detected clearly in this study.

ABSTRAK Terowongan Eksplorasi Uranium Eko Remaja Kalan (TEURK) di Kalimantan Barat yang dibangun pada tahun 1980 merupakan salah satu sarana penelitian cebakan uranium di Indonesia. Terowongan ini menembus Bukit Eko Remaja sepanjang 618 m, mulai dari pintu Remaja hingga TRK-7. Mineralisasi uranium di lokasi ini dikontrol oleh urat-urat tak beraturan (stockwork) yang sangat rapat pada batuan metalanau dan metapelit. Tingginya kerapatan struktur geologi tersebut membentuk beberapa zona lemah di dalam terowongan. Zona lemah tersebut berpotensi menyebabkan terjadinya longsor batu dan tanah. Penyangga sementara terbuat dari tiang-tiang kayu dipasang di zona tersebut untuk perkuatan terowongan. Saat ini tiang kayu tersebut tidak lagi mampu menyangga terowongan sehingga sering terjadi longsor batu dan tanah di dalam terowongan. Penelitian ini bertujuan untuk mengetahui kualitas massa batuan aktual dan menentukan jenis perkuatan yang sesuai agar terowongan tetap aman. Survei palu Schmidt dan scanline pada zona tak berpenyangga (kedalaman 50–297 m dan 355–538 m) dilakukan untuk mengambil data parameter klasifikasi Rock Mass Rating (RMR). Hasil pengukuran menunjukkan bahwa massa batuan TEURK di kedalaman tersebut memiliki nilai RMR 52-71 (sedang–baik). Perkuatan yang direkomendasikan adalah pemasangan baut batu dan beton semprot konvensional.ABSTRACT Tunnel for Exploration of Uranium Eko Remaja Kalan (TEURK) in West Kalimantan, built-in 1980, is one of the uranium deposit research facilities in Indonesia. The tunnel penetrated Eko Remaja Hill along 618 m, from Remaja to TRK-7 access. Uranium mineralization in this area controlled by dense stockwork veins on metasilt and metasandstone rocks. The high-dense geological structures create some weak zones in the tunnel. These zones are potentially causing rocks and soil slides. Temporary supports made of wood-piles were installed in these zones to support the tunnel. Currently, these piles are not capable at the tunnel, so that rocks and soil slides occurred inside the tunnel. The research aimed to determine the quality of actual rock mass and determine the appropriate type of reinforcement to keep the tunnel safe. Schmidt hammer and scanline surveys on the unsupported zone (50–297 m and 355–538 m depth) carried out to collect the classification parameter data of Rock Mass Rating (RMR). The measurement result shows that the rock mass of TEURK on the depth has an RMR value of 52–71 (fair-good). Reinforcement recommendations for the tunnel are rock bolts and conventional shotcretes installation.

ABSTRAKPengukuran geolistrik dengan menggunakan konfigurasi schlumberger telah dilakukan di Pulau Gili Ketapang, sebuah pulau kecil yang memiliki kepadatan penduduk mencapai 12.356 jiwa/km2. Pengukuran dilakukan di 8 lokasi menggunakan metode pada 8 titik Vertical Electrical Sounding (VES). Hasil pengolahan data geolistrik menunjukkan nilai tahanan jenis akuifer berkisar antara 2,71–206 Ωm pada litologi batugamping pasiran. Potensi volume akuifer terbesar berdasarkan model 2D akuifer air tanah berada di lokasi K-03 dan K-17. Model 3D akuifer air tanah menunjukkan bahwa volume akuifer sebesar 27.689.400 m3 atau sekitar 27.689.400.000 liter. Air tanah di dalam akuifer dapat bertahan selama 68 tahun jika tidak terjadi kenaikan populasi. Selain itu, air tanah juga akan bertahan meskipun tidak terjadi penambahan air di dalam akuifer, baik secara alami ataupun buatan.ABSTRACTGeoelectric measurement using Schlumberger configuration was carried out in Gili Ketapang Island, a small island with a population density of 12,356 people/km2. The measurement conducted at 8 locations using a vertical electrical sounding (VES) method. The result of geoelectric data processing shows aquifer resistivity value ranging from 2.71–206 Ωm at the sandy limestone lithology. The largest aquifer volume potency based on the 2D groundwater aquifer model is in the K-03 and K-17 location. The 3D groundwater aquifer model shows that the aquifer volume is 27,689,400 m3 or about 27.689.400.000 liters. The groundwater inside the aquifer will last within 68 years in a condition where there is no population increase. Besides, the groundwater also lasts even there is no water addition inside the aquifer, by natural or artificial

ABSTRACT In resources estimation, geostatistics methods have been widely used with the benefit of additional attribute tools to classify resources category. However, inverse distance weighting (IDW) is the only method used previously for estimating the uranium resources in Indonesia. The IDW method provides no additional attribute that could be used to classify the resources category. The objective of research is to find the best practice on geostatistics application in uranium resource estimation adjusted with geological information and determination of acceptable geostatistics estimation attribute for resources categorization. Geostatistics analysis in Rabau Hulu Sector was started with correlation of the orebody between boreholes. The orebodies in Rabau Hulu Sectors are separated individual domain which further considered has the hard domain. The orebody-15 was selected for further geostatistics analysis due to its wide distribution and penetrated most by borehole. Stages in geostatistics analysis cover downhole composites, basic statistics analysis, outliers determination, variogram analysis, and calculation on the anisotropy ellipsoid. Geostatistics analysis shows the availability of the application for two resources estimation attributes, which are kriging efficiency and kriging variance. Based on technical judgment of the orebody continuity versus the borehole intensity, the kriging efficiency is considered compatible with geological information and could be used as parameter for determination of the resources category. ABSTRAK Pada estimasi sumber daya, metode geostatistik telah banyak digunakan dengan kelebihan adanya alat atribut tambahan untuk mengklasifikasikan kategori sumber daya. Namun demikian, pembobotan inverse distance (IDW) adalah satu-satunya metode yang sebelumnya digunakan untuk mengestimasi sumber daya uranium di Indonesia. Metode IDW tidak memberikan tambahan atribut yang dapat digunakan dalam mengklasifikasikan kategori sumber daya. Tujuan dari penelitian adalah mendapatkan praktek terbaik untuk aplikasi geostatistik pada estimasi sumber daya disesuaikan dengan informasi geologi dan penentuan atribut geostatistik yang dapat digunakan untuk kategorisasi sumber daya. Analisis geostatistik di Sektor Rabau Hulu diawali dengan korelasi tubuh bijih antara lubang bor. Tubuh-tubuh bijih di Sektor Rabau Hulu merupakan domain individual yang selanjutnya dipertimbangkan memiliki domain tegas. Tubuh bijih-15 dipilih untuk digunakan pada analisis geostatistik selanjutnya karena distribusinya yang luas dan paling banyak dipenetrasi bor. Tahapan dalam analisis geostatistik mencakup komposit downhole, analisis statistik dasar, determinasi outliers, analisis variogram, dan perhitungan ellipsoid anisotropi. Analisis geostatistik menghasilkan kemungkinan aplikasi dua atribut estimasi sumber daya, yaitu kriging efisiensi dan kriging varians. Berdasarkan penilaian teknis kemenerusan tubuh bijih terhadap intensitas lubang bor, kriging efisiensi dipertimbangkan sesuai dengan informasi geologi dan dapat digunakan sebagai parameter untuk penentuan kategori sumber daya.

ABSTRAK Telah dilakukan proses pemisahan itrium dengan cara ekstraksi menggunakan solven TOPO. Tujuan dari penelitian ini adalah untuk mengetahui kondisi optimum pengaruh variasi konsentrasi ekstraktan, waktu pengadukan, dan keasaman umpan logam tanah jarang serta mengetahui koefisien distribusi (Kd), faktor pisah (FP), dan efisiensi ekstraksi (%), dengan metode ekstraksi cair-cair. Umpan yang digunakan adalah logam tanah jarang dari pasir senotim. Ekstraktan yang digunakan dalam penelitian adalah TOPO (tri-n-oktilfosfina oksida). Kadar itrium (Y), disprosium (Dy), dan gadolinium (Gd) ditentukan menggunakan spektrometer pendar sinar-X. Kondisi optimum yang diperoleh dari penelitian proses ekstraksi ini meliputi: konsentrasi ekstraktan 20% TOPO dalam kerosin, waktu pengadukan 15 menit, keasaman umpan 0,5 M. Nilai koefisien distribusi yang diperoleh Y = 5,61; Dy = 2,06; Gd = 0,99. Efisiensi ekstraksi Y = 85,13%, Dy = 67,80%, Gd = 50,17% sedangkan faktor pisah Y-Dy = 2,7186 dan Y-Gd = 5,6861. ABSTRACT Separation process of yttrium by extraction using TOPO solvents has been done. The purpose of this study is to find out the optimum condition of the variation effect of extractant concentration, stirring time, and acidity of the rare earth feed and to determine the distribution coefficient, separation factor, and extraction efficiency (%), using the liquid-liquid extraction method. The feed used were rare earth elements of xenotime sand. The extractant used in the research were TOPO (tri-n-octylphosphine oxide). Concentration of yttrium (Y), disprosium (Dy), and gadolinium (Gd) were determined using X-ray fluorescene spectrometer. Optimum conditions of the extraction process obtained from this study were: TOPO extractant concentration in kerosene 20%, stirring time 15 minutes, acidity of feed 0.5 M. Obtained value of distribution coefficient Y = 5.61; Dy = 2.06; Gd = 0.99. For extraction efficiency Y = 85.13%, Dy = 67.80%, Gd = 50.17% whereas separation factor Y-Dy = 2.7186 and Y-Gd = 5.6861.

Penelitian tentang teknologi pengolahan zircon terus dilakukan untuk mengikuti kebutuhan industri pasar. Pengolahan natrium zirkonat dengan pelindian menggunakan asam klorida sebagai pelarut telah dilkukan. Penelitian ini bertujuan mempelajari pengaruh ukuran butir, temperatur, dan kecepatan pengadukan terhadap zirkon terambil. Penelitian dilakukan dengan memasukkan pelarut (asam klorida 4 N) ke dalam reaktor, kemudian pelarut tersebut dipanaskan sambil diaduk. Umpan dengan ukuran butir tertentu dimasukkan ke dalam reaktor. Kondisi temperatur dan kecepatan pengadukan dijaga tetap. Setelah kondisi operasi tercapai, proses dihentikan kemudian disaring. Hasil penelitian dengan analisis XRF menunjukkan bahwa kondisi proses optimum dicapai pada ukuran butir 90 µm, temperatur 80 oC dan kecepatan pengadukan 200 rpm. Pada kondisi tersebut zirkon terambil sebesar 84.50 %. Research on zircone processing technology has been continued to follow industrial market needed. Treatment of sodium zirconate with leaching process using hydrochloric acid as solvent has been conducted. The aim of the study is to evaluate the effect of grain size, temperature, and speed of stirring on the extracted zircon. The research starting with introduced the solvent (chloride acid 4 N) into the reactor, then heated while stirring. The feed with a certain grain size was introduced into the reactor. The temperature and stirring conditions were kept steady. Once the operating conditions are reached, the process is stopped and then filtered. The results with XRF analysis showed that the optimum process conditions were achieved on 90 μm grain size, the temperature of 80oC, and stirring speed of 200 rpm. The amount of zircon that taken out were 84.50% on this conditions.