Empirical Application of Generalized Rayleigh Distribution for Mineral Resource Estimation of Seabed Polymetallic Nodules

An efficient empirical statistical method is developed to improve the process of mineral resource estimation of seabed polymetallic nodules and is applied to analyze the abundance of seabed polymetallic nodules in the Clarion Clipperton Zone (CCZ). The newly proposed method is based on three hypotheses as the foundation for a model of “idealized nodules”, which was validated by analyzing nodule samples collected from the seabed within the Tonga Offshore Mining Limited (TOML) exploration contract. Once validated, the “idealized nodule” model was used to deduce a set of empirical formulae for predicting the nodule resources, in terms of percentage coverage and abundance. The formulae were then applied to analyzing a total of 188 sets of nodule samples collected across the TOML areas, comprising box-core samples and towed camera images as well as other detailed box-core sample measurements from the literature. Numerical results for nodule abundance and coverage predictions were compared with field measurements, and unbiased agreement has been reached. The new method has the potential to achieve more accurate mineral resource estimation with reduced sample numbers and sizes. They may also have application in improving the efficiency of design and configuration of mining equipment.

Empirical Application of Generalized Rayleigh Distribution for Mineral Resource Estimation of Seabed Polymetallic Nodules

An effective empirical statistical method is developed to improve the process of mineral resource estimation of seabed polymetallic nodules and is applied to analyse the abundance of seabed polymetallic nodules in the Clarion Clipperton Zone (CCZ). The newly proposed method is based on three hypotheses as the foundation for a model of “Idealized Nodules”, which was validated by analysing nodule samples collected from the seabed within the Tonga Offshore Mining Limited (TOML) exploration contract. Once validated, the “Idealized Nodule” model was used to deduce a set of empirical formulae for predicting the nodule resources, in terms of Percentage Coverage and Abundance. The formulae were then applied to analysing a total of 188 sets of nodule samples collected across the TOML areas, comprising box-core samples and towed camera images collected by one of the authors and detailed in [4]. The analysis also relies upon detailed box-core sample measurements from other areas reported by [7]. Numerical results for resource prediction were compared with field measurements, and reasonable agreement has been achieved. The new method has the potential to achieve more accurate mineral resource estimation with reduced sample numbers and sizes. They may also have application in improving the efficiency of design and configuration of mining equipment.

Analisa Titik Operasi Optimum Pompa Slurry pada Bucket Wheel Dredger dengan Variasi Sudut Gali 30°, 35° dan 40°

PT.Timah (Persero) Tbk. merupakan perusahaan tambang timah dengan cadangan terbesar di dunia yang menggunakan kapal isap tipe Bucket Wheel Dredger sebagai salah satu metode penambangan lepas pantai. Untuk mendistribuskan material tambang dari dasar laut menuju unit penyaringan, digunakan air sebagai media pembawa dibantu dengan pompa melalui jaringan pemipaan. Pada proses pengerukan, ternyata didapat masih ada material logam timah yang tertinggal di dasar lautan. Hal ini menyebabkan pengerukan menjadi kurang maksimal. Oleh karena itu, diperlukan analisa untuk mencari kondisi operasi optimum untuk setiap kedalaman penggalian. Dalam penelitian ini, dilakukan perhitungan head secara teoritis dimana prosedur dimulai dengan pengumpulan data pendukung, kemudian melakukan perhitungan untuk mendapatkan hasil. Dalam kondisi lapangan, didapat perubahan luas penampang pipa dikarenakan erosi. Untuk menghitung head, digunakan persamaan Bernoulli, untuk kerugian head major dan head minor digunakan persamaan Darcy-Weisbach dimana kapasitas aliran adalah tetap 7747.2 m3/h dengan variasi sudut gali 30°,35°, dan 40° pada luas penampang dengan pemakaian baru, 1 bulan, 2 bulan, dan 3 bulan. Didapat titik operasi optimum pompa slurry untuk setiap sudut secara berurutan adalah pada 517.08 rpm, 517.44 rpm, 520.96 rpm untuk pemakaian baru; 517.44 rpm, 517.44 rpm, 521.664 rpm untuk pemakaian satu bulan ; 517.44 rpm, 517.792 rpm, 520.96 rpm untuk pemakaian dua bulan; 511.808 rpm, 512.16 rpm, 513.92 rpm untuk tiga bulan. PT. Timah (Persero) Tbk. is the largest tin mining company in the world which uses suction ships of Bucket Wheel Dredger as one of the offshore mining methods. Water is used as a carrier medium to distribute mining materials from seafloor to the filtration unit by pumps through piping networks. During the dredging process, it is found there is still tin metal material left on the ocean floor. This causes dredging process is less optimal. Based on the condition, it needed an analysis to find optimum operating process for each excavation depth. In this research, theoretical head calculations were carried out where the procedure began with supporting data collection, then calculated it to get results. In field conditions, changes in pipe cross section were obtained due to erosion. The Bernoulli equation was used to calculate head, Darcy-Weisbach equation was used for the loss of major and minor head where the flow capacity was fixed at 7747.2 m3/h with digging angle variations of 30 °, 35 °, and 40 ° in the cross-sectional area for new, 1 month, 2 months and 3 months usage. The optimum operating point of the slurry pump for each angles were obtained at 517.08 rpm, 517.44 rpm, 520.96 rpm for new usage; 517.44 rpm, 517.44 rpm, 521,664 rpm for one month usage; 517.44 rpm, 517,792 rpm, 520.96 rpm for two months usage; and 511,808 rpm, 512.16 rpm, 513.92 rpm for three months usage.

Kajian Performansi Pompa Slurry pada Cutter Suction Dredger dengan Variasi Sudut Gali 35°, 40° dan 45°

Cutter Suction Dredger adalah salah satu metode penambangan lepas pantai. Untuk mendistribuskan material tambang dari dasar laut menuju unit penyaringan, digunakan air sebagai media pembawa dibantu dengan pompa melalui jaringan pemipaan. Sistem pemipaan merupakan bagian yang sangat penting dalam menyalurkan fluida. Dalam pengoperasiannya didapat kerugian yang menimbulkan beban tambahan yang ditimbulkan oleh gesekan antara fluida dan padatan denga pipa beserta dengan komponennya.Dalam penelitian ini, peneliti melakukan perhitungan head secara teoritis dimana prosedur dimulai dengan pengumpulan data data pendukung, kemudian melakukan perhitungan untuk mendapatkan hasil. Dalam kondisi lapangan, didapat terdapat perubahan luas penampang pipa dikarenakan oleh gesekan . Untuk menghitung head, digunakan persamaan Bernoulli, untuk kerugian head major dan head minor digunakan persamaan Darcy-Weisbach dimana kapasitas aliran adalah tetap sebesar 250 m3/h solid insitu dengan variasi sudut gali 25°,35°, dan 45° pada luas penampang dengan pemakaian baru, 1 bulan, 2 bulan, dan 3 bulan. Didapat besar head untuk setiap sudut secara berurutan adalah 399 rpm, 414.762 rpm, dan 433.984 rpm untuk pemakaian baru, 398.808 rpm, 413.987 rpm, 432.713 rpm untuk pemakaian 1 bulan, 397.368 rpm, 412.888 rpm, 428.125 rpm untuk pemakaian 2 bulan, dan 395.263 rpm, 411.021 rpm, 420.069 rpm untuk pemakaian 3 bulan. Cutter Suction Dredger is an offshore mining method. Water is used as a carrier medium to distribute mining material from the seafloor to the filtration unit, by pump through piping networks. Piping system is a very important part in channeling fluid. In the operation, the loss is obtained because of the additional burdens caused by friction between fluid and solid with pipe along with its components. In this study, researcher conducted theoretical head calculations where the procedure started by collecting supporting data, then calculated it to get results. In field conditions, it was found that there was a change in cross-sectional area of ​​the pipe due to friction. Bernoulli equation was used to calculate head, Darcy-Weisbach equation was used for loss of major head and head minor where flow capacity was fixed at 250 m3/h solid in situ with variation of digging angle were 25 °, 35 °, and 45 ° on cross-sectional area for new, 1 month, 2 months and 3 months usage. The head sizes for each angle sequentially were 399 rpm, 414,762 rpm and 433,984 rpm for new usage; 398,808 rpm, 413,987 rpm, 432,713 rpm for 1 month usage; 397,368 rpm, 412,888 rpm, 428,128 rpm, 428,125 rpm for 2 months usage; and 395,263 rpm, 411,021 rpm, 420,069 rpm for 3 months usage.

Kajian Performansi Pompa Slurry pada Bucket Wheel Dredger dengan Variasi Sudut Gali 45°, 50° dan 55°

PT.Timah (Persero) Tbk. merupakan perusahaan tambang timah dengan cadangan timah terbesar di dunia yang menggunakan kapal keruk tipe Bucket Wheel Dredger sebagai salah satu metode penambangan lepas pantai. Proses penambangan ini membutuhkan biaya yang besar, tetapi akibat kondisi operasi yang tidak optimal, dibutuhkan waktu dan biaya lebih dalam proses penambangannya. Oleh karena itu diperlukan kajian yang lebih mendalam untuk mengetahui kondisi operasi optimal. Dalam penelitian ini, peneliti melakukan perhitungan head secara teoritis dimana prosedur dimulai dengan pengumpulan data data pendukung, kemudian melakukan perhitungan untuk mendapatkan hasil. Untuk mendapatkan nilai head, digunakan persamaan Bernoulli. Untuk kerugian head major dan head minor digunakan persamaan Darcy-Weisbach. Kapasitas aliran adalah tetap sebesar 7747.2 m3/h padatan dengan variasi sudut gali 45°, 50°, dan 55° pada luas penampang pemakaian baru, satu bulan, dua bulan, dan tiga bulan. Setelah didapat besar head, didapat putaran optimum pompa untuk sudut operasi 45°, 50°, dan 55° secara berurutan adalah 522.470 rpm, 523.569 rpm, dan 524.550 rpm untuk pemakaian baru, 522.614 rpm, 523.706 rpm, dan 525.690 rpm untuk pemakaian satu bulan, 521.829 rpm, 522.931 rpm, dan 523.917 rpm untuk pemkaian dua bulan, 521.030 rpm, 522.122 rpm dan 523.142 rpm untuk pemakaian tiga bulan. PT. Timah (Persero) Tbk. is a tin mining company with the largest tin reserve in the world which operates Bucket Wheel Dredger as an offshore mining method. This mining process requires a large amount of cost. It needs more time and cost in mining process due to non-optimal operating conditions. Therefore, a more in-depth study is needed to determine the optimal operating conditions. In this study, the researcher performed theoretical head calculations where the procedure began by collecting supporting data, then performing calculations to obtain the results. Bernoulli equation was used to get the head value, whereas, Darcy-Weisbach equation was used for the loss of major head and minor head. The flow capacity was fixed at 7747.2 m3/h solid with the variations of digging angles of 45°, 50°, and 55° on the cross-sectional area for new, one month, two months, and three months usages. After obtaining a head value, the optimum pump rotations obtained for operating angles of 45 °, 50 °, and 55 ° respectively are 522,470 rpm, 523,569 rpm, and 524,550 rpm for new usage, 522,614 rpm, 523,706 rpm and 525,690 rpm for one month usage, 521,829 rpm, 522,931 rpm, and 523,917 rpm for two months usage, 521,030 rpm, 522.122 rpm and 523,142 rpm for three months usage.

A computational fluid dynamics study on the solid mineral particles-laden flow in a novel offshore agitated vessel

Most seabeds are unexplored and rich in mineral deposits, making offshore mining a promising activity. However, offshore operation brings in great challenges from technical equipment to physical space. For instance, an offshore agitated vessel is supposed to stabilize the solids concentration from the underwater mining and make little impact on the stability of the platform or ship. For this reason, we proposed a novel offshore agitated vessel. The whole system based on the arrangement of the mineral processing platform and the slurry mix flow rate is obtained from the previous design stage. Large-scale unsteady computational fluid dynamics simulations are performed to calculate its effectiveness. The simulation model equipped with two pitched blade turbines and inlets/outlets is investigated. A classical Eulerian multiphase model and a modification of the standard k-ε eddy-viscosity turbulence model are adopted to simulate the dense solid–liquid suspension dynamics. Computational fluid dynamics results were found to be in satisfactory agreement with the theoretical predictions. The agitated system obtained was found to be effective to stabilize the solid particle concentration. In order to achieve a higher concentration at outlets and lower power consumption, further improvement was made and validated by computational fluid dynamics simulations. The proposed offshore mechanical agitated vessel could be equipped on offshore mining.

ANALISIS PENENTUAN SUBSEKTOR PRIORITAS PADA BIDANG KELAUTAN INDONESIA (PENDEKATAN DETERMINISTIK INPUT-OUTPUT)

The aim of this study is to determine priority subsectors in the field of Indonesian marine. The analysis is done by input-output approach. This study has found several priority subsectors classified into two groups, namely short-term and long-term priority subsector groups. Short-term priority subsectors group in the Indonesian marine sector include fish processing and preservation industries, marine tourism, marine and fisheries support, marine and fisheries education and research services, and fisheries services. Meanwhile, for the long-term priority subsectors group the Indonesian marine sector comprises oil and gas mining and refining, marine trade services, offshore mining, fishery services and shrimp industry.Keywords: Input-Output, Multiplier Effect, Backward Linkages, Forward Linkages

Local Fisherman Resistance in Kelapa Kampit Coastal Area Toward Offshore Mining Activities

Tin mining activities in Belitung Island have lasted since colonialism era to this moment. In 1990s tin exploitation in Belitung was stopped as it was assessed as no longer productive. In 1999, however, the mining had massively recommenced and at the same time, tourism and fishery were being actively developed as the new economic power. Recently, tin exploitation has shifted into offshore, and since then the conflicts began to appear. Rejection actions were continuously performed by fishermen through anti offshore mining audience, demonstration and campaign in social media. One of the rejections was when production suction vessel entered Pering waters, KelapaKampit East Belitung. At the urging of local fisherman group, written agreement between East and West Belitung head regencies, as well as the special committee recommendation of East Belitung house of representative, finally the suction vessel moved out from Pering waters. This study aimed to analyze fishermen’s and stakeholders’ knowledge, attitude, and expectationtoward offshore mining activities. Their point of views are needed in order to obtain complete perspective regarding the positive and negative sides, whether there is the meeting point among various interests and how long this conflicts will last. It is a mixed method research between qualitative and quantitative one. Quantitative approach employed questionnaire and SPSS 20 was used to analyze the results. Data collection technique used non-probability sampling with specific characteristic, fisherman community in Pering coastal area in which the amount applied Solvin theory. Qualitative approach was used to explore various phenomenons developing in society through interview with stakeholders related to offshore mining issues. Qualitative research was applied to explore phenomenon developing on site, either historically or contextually. Primary data was collected through interview with stakeholders in East Belitung related to the major issues raised. Based on the questionnaire results on fishermen and the interview with the related stakeholders, there were some findings. First, fishermen’s knowledge about offshore mining was very limited. Second, most fishermen were agreed that offshore mining damaged ecosystem, reduced catching and disturbed tourism. Third, the expectation if offshore mining keep operating, fishermen will continuously fight for it. In stakeholder and social society level; though there is one supporting offshore mining, so far however, the majority still put their side on fishermen, tourism, and environment’s interest and thus refusing offshore mining.