Jurnal Puslitbang tekMira (Teknologi Mineral dan Batubara)
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TIDAK SEDERHANA MEWUJUDKAN INDUSTRI PENGOLAHAN NIKEL LATERIT KADAR RENDAH DI INDONESIA SEHUBUNGAN DENGAN UNDANG-UNDANG MINERBA 2009
No full textAda dua jalur proses untuk mengolah bijih nikel oksida yang lazim disebut laterit, yaitu pirometalurgi dan hidrometalurgi. Pirometalurgi digunakan untuk mengolah laterit jenis saprolit berkadar nikel tinggi (Ni≥1,8%) untuk memproduksi FeNi atau Ni matte. Hidrometalurgi digunakan untuk mengolah laterit kadar rendah (Ni<1,8%) yang belum ada di tanah air. Dalam perkembangannya pirometalurgi digunakan untuk mengolah laterit kadar rendah menghasilkan NCPI/NPI (Nickel Contain Pig Iron/Nickel Pig Iron) di Tiongkok. Selanjutnya NCPI/NPI digunakan sendiri oleh Tiongkok sebagai pengganti FeNi untuk membuat besi-baja tahan karat. Bahan baku pembuatan NCPI/NPI Tiongkok diperoleh dari mengimpor laterit Filipina dan Indonesia. Dengan mulai berlakunya UU Minerba (Mineral dan Batubara) tahun 2009 yang mewajibkan bahan baku harus diolah di dalam negeri sebelum diekspor, dan melarang ekspor bahan baku mulai 12 Januari 2014. Maka Indonesia mungkin akan menghadapi masalah hukum dagang internasional yang tidak sederhana sebagai konsekuensi dari larangan ekspor mineral. Masalah lainnya bagaimana harus mengolah mineral di dalam negeri, dan siapa yang akan menyerap pasar hasil olahan mineral. Melihat kenyataan ini pemerintah harus mengoptimalkan litbang (penelitian dan pengembangan) yang ada di departemen maupun non departemen
PETROGRAPHIC CHARACTERISTICS OF SELECTED TERTIARY COALS FROM WESTERN INDONESIA ACCORDING TO THEIR GEOLOGICAL ASPECTS
No full textSelected Tertiary coals from the western part of Indonesia (Sumatera, Kalimantan and Java) indicate similarities and differences in type and rank characteristics. These coals reflect their geological setting, particularly for intrusive and stratigraphic aspects. Type and rank of the coals were assessed by petrographic examination. The coals are mainly dominated by vitrinite, common liptinite and rare inertinite and mineral matter. Vitrinite macerals are dominated detrovitrinite and telovitrinite. Resinite, cutinite and suberinite are the dominant liptinite macerals in the coals. Inertinite macerals in the coals consist of semifusinite, sclerotinite and inertodetrinite. The type differences largely reflect climatic influence and differences in peat conditions. In spite of short geological history, the coals exhibit variable vitrinite reflectances. The high vitrinite reflectance of the coals is a result of higher regional coalification levels in the basins associated with greater cover and effects of igneous intrusions
EXTRACTING SILVER FROM ANODE SLIME AFTER LEAD AND GOLD SEPARATIONS
No full textAnode slime, a byproduct from the process of copper electrorefining into the copper cathode, contains several valuable elements that can be extracted after Cu and Pb separations. Another alternative route for extracting the precious metals is still needed in terms of gaining more economical route. This research aims to seek the new route to extract the precious metals, especially silver from anode slime. In these experiments, the anode slime was obtained from PT Smelting Gresik. The lead was separated to produce the residue which was then chlorinated to extract the gold. Later the residue was used for extracting the silver by dissolving it in ammonium hydroxide solution with varying time dissolutions and concentrations and later dissolving in hydrochloric acid to form silver chloride which was reduced to metallic silver. These experiments had two trials. The first one related to directly using residual chlorination after gold separation and the second one employed the same residual chlorination but processed through de-chlorination by adding sodium carbonate. The result showed that the highest silver recovery of 53.56% related to 5 M ammonium hydroxide concentration, the temperature of 30°C, dissolution time of 60 minutes. Recovery of 53.78% was achieved at 7 M ammonium hydroxide, the temperature of 30°C, dissolution time of 60 minutes. The feed of those experiments came from direct residual chlorination, while chlorination residue that underwent de-chlorination produced silver recovery of 94.95% with leaching conditions of 5 M ammonium hydroxide, the heating temperature of 30°C and leaching time of 60 minutes. The latest recovery was relatively high resulted in the process could be scaled up to a continuous system
THE OCCURRENCE OF METHANE GAS SEEPAGES IN THE UPPER KETUNGAU AREA, WEST KALIMANTAN
No full textUplifting event on the Boyan Melange, that formerly known as the Semitau High in West Kalimantan has resulted in the separated Ketungau and Melawi Basins in the Late Cretaceous or Early Tertiary time. Initial stage of sedimentary deposition within the Ketungau Basin occurred in Early Eocene, depositing a fluvial conglomerate unit that subsequently changes upwards into a shallow marine and lacustrine unit of the Kantu Formation. The Eocene Kantu Formation consists of alternating dark grey and laminated carbonaceous shale, mudstone and siltstone with coal seam intercalations and the Ketungau Formation, which is composed of alternating dark grey and laminated carbonaceous shale, claystone, siltstone with coal seam intercalations inferred to be able performed as a source rocks for initial biogenic methane. On the other hand, the Oligo-Miocene Tutoop Sandstone that consists of dominantly a coarse- to fine-grained clastic unit may potentially conduct as a secondary reservoir rock for coalbed methane. Gas seepages that have been observed on surface along the tributary of Peturau and Sebuntung Rivers in the Upper Ketungau region is presumed to be derived from a coalbed methane source within the Kantu and Ketungau Formations. The methane gas is assummed to be ascending on surface through structural faults that trending NW-SE direction
COMPUTATIONAL ANALYSIS OF ASH EROSION ON SUPERHEATER TUBES IN COAL FIRED POWERPLANT
No full textThis paper presents a computational analysis of fly ash erosion on superheater tubes of a coal furnace. The investigation was held based on a hypothesis that erosion by coal ash particles have caused an untimely fail- ure of a superheater tube during the initial running of a relatively new coal fired power plant. Material erosion is usually caused by several corresponding factors, therefore, it is necessary to examine the process taken by the coal ash to wear out superheater material before conclusions on the ash factor are drawn. This work applies a combination method of analysis using mathematical model and computational fluid dynamics (CFD) simulation. The mathematical model was used to calculate the amount of erosion by the fly ash particles and CFD simulation was employed to examine the velocity profile of combustion products around the superheater bank. The CFD simulation was based on the real scale and the design parameters of the power plant. The simulation shows that the velocity vector of the combustion products around superheater bank varies from 1 to 20 m/s magnitude with impacting angle varies from 0 to 90° relative to the vertical position of the superheater. Ash data were taken from the actual coal used during the operation and the design specified coal according to the equipment specification. Mathematical model was formulated for a single ash particle and for ash bulk. The results show that differences in the ash particle parameters result in different amount of material removal which means that ash particles affect the wear out of the material. As an overall, for each ash particle, the maximum erosion occurs at impacting angle of 17°. The impacting angle is used further in determining the amount of mass removal by varying the velocity and the abrasiveness of ash particles. At the maximum level of erosion, which is the maximum velocity calculated from the CFD simulation (20 m/s), every kilogram ash particles containing 46.54 % SiO2 with ash particle average diameter 500 micron is capable to remove about 0.0045 miligram alloy steel material. The maximum penetration of the ash particles into the superheater material is found at the maxi- mum velocity obtained from the CFD simulation that is 20 m/s. The maximum penetration is 0.049 mm which is about 1.53 % of the pipe thickness. The superheater pipe is made of alloy steel material type A213-T91 with the thickness of pipe wall 3.2 mm. The magnitude of mass removal is considered relatively trivial to cause the thinning of material in a short period. This proves that coal ash particles will undergo a timely process to wear out superheater material, it is predictable and does not immediately cause erosion or failure. A brief physical examination was carried out to compare the results of the analysis and the causes of failures. It was found out that the failed superheater pipe had undergone clogging which caused overheating followed by pipe burst