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"Ferokrom 45-75 Cr dan 35-50 Fe paduan penting pembuatan baja tahan karat karena sifat kekuatan dan ketahanan korosi yang tinggi. Ferokrom berasal dari endapan kromit di wilayah Indonesia adanya berkadar rendah dengan ratio Cr/Fe < 1.5 sehingga diperlukan benefisiasi. Tahapan benefisiasinya pemisahan magnetik lemah dilanyutkan pemanggangan temperatur, waktu, jenis reduktor dan berat CaCO3 , hasil pemanggangan dilakukan pemisahan magnetik kuat dan diuji xrf dan xrd. Parameter optimal benefisiasi untuk pembuatan briket input peleburan tanur SAF. Peleburan briket kromit diteliti pengaruh basisitas terhadap parameter ratio Cr/Fe, kadar kromium dan besi, konsumsi energi/berat produk . Pengaruh temperatur pemanggangan 800, 1000 dan 1200 oC terhadap ratio Cr/Fe optimum temperaturnya 1000 oC ratio Cr/Fe sebesar 1,53. Pengaruh waktu pemanggangan 30, 60 dan 90 menit terhadap ratio Cr/Fe optimum waktunya 60 menit ratio Cr/Fe sebesar 1,53. Pengaruh reduktor grafit, kokas dan arang batok terhadap ratio Cr/Fe optimum redukror arang batok ratio Cr/Fe sebesar 1,60. Pengaruh wt CaCO3 5 , 10 dan 20 terhadap ratio Cr/Fe optimum wt CaCO3 pada 20 rasio Cr/Fe sebesar 1,60. Basisitas terak = 2 memberikan ratio Cr/Fe optimum =1,06 , kadar Cr = 50,07 . Konsumsi energi/berat logam optimum 5,7 Kwh/Kg pada nilai basisitas 1,2.

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Ferrochrome is an important alloy of stainless steel due to its high strength and corrosion resistance. Ferromchrome is derived chromite in the Indonesia region low grade Cr Fe "

"ABSTRAKSekitar 95 dari seluruh bijih kromit yang ditambang di dunia digunakan sebagai bahan baku pembuatan ferrochromium FeCr . Pada penelitian sebelumnya, peleburan pasir kromit kadar rendah tidak dapat menghasilkan ferrochromium dengan kadar Cr ge; 60 sehingga pasir kromit kadar rendah harus dilakukan proses benefisiasi untuk meningkatkan kadar Cr dan rasio Cr/Fe sebelum proses peleburan menjadi ferrochromium. Penelitian ini menggunakan pasir kromit kadar rendah asal Kabupaten Konawe, Sulawesi Selatan. Proses benefisiasi yang dilakukan adalah magnetic separation menggunakan medan magnet 800 Gauss dan reduction roasting selama 60 menit pada temperatur 1000 C dengan variabel jumlah reduktor, yaitu 5 lean carbon, stokiometri, 5 excess carbon dan 10 excess carbon serta jumlah aditif CaSO4, yaitu 5 , 10 , 15 , dan 20 . Rasio Cr/Fe dan kadar Cr pada bahan baku pasir kromit adalah 0,9 dan 19,27 . Kromium dalam pasir kromit kadar rendah berada dalam mineral magnesiochromite, aluminian, yang terasosiasi dengan unsur besi dalam struktur spinel. Magnetic separation yang dilakukan pada bahan baku pasir kromit menghasilkan kenaikan rasio Cr/Fe dan kadar Cr menjadi sebesar 1,31 dan 21,33 akibat adanya pemisahan antara kromit yang bersifat paramagnetik dan pengotornya yang bersifat magnetik. Selanjutnya, hasil terbaik dari reduction roasting yang dilanjutkan dengan magnetic separation diperoleh pada proses reduction roasting dengan menggunakan 10 excess carbon dan 20 CaSO4, yaitu menghasilkan rasio Cr/Fe dan kadar Cr sebesar 1,19 dan 20,48 atau setara dengan FeCr yang mengandung 54,5 Cr.

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ABSTRACTAround 95 of mined chromite ore in the world is utilized as raw material for ferrochromium making process. According to the previous research, the melting of low grade chromite sand could not produce ferrochromium with Cr ge 60 so that low grade chromite sand has to be beneficiated to enhance the chromium grade and Cr Fe ratio before the melting process to produce ferrochromium. This research utilized low grade chromite sand from Konawe District, South Sulawesi. The beneficiation processes that was conducted were magnetic separation, which used magnetic field of 800 Gauss and reduction roasting for 60 minutes at 1000 C with various reductant dosage, 5 lean carbon, stoichiometry, 5 excess carbon and 10 excess carbon along with various dosage of CaSO4 as additive, 5 , 10 , 15 , and 20 . Cr Fe ratio and chromium content in low grade chromite sand are 0.9 and 19.27 . Chromium, in low grade schromite sand, was existed as magnesiochromite, aluminian, which associated with iron in spinel structure. Magnetic sseparation process that was conducted to the raw material, resulted in enhancement of Cr Fe ratio and chromium content to 1.31 and 21.33 due to separation of the paramagnetic chromite from the magnetic gangue. Furthermore, the best result from reduction roasting followed by magnetic separation was obtained when reduction roasting used 10 excess carbon and 20 CaSO4, which resulted at 1.19 of Cr Fe ratio and 20.48 of chromium content or equivalent to FeCr with 54.5 Cr."

"ABSTRAKMelalui Proses Benefisiasi dengan Variabel Jumlah Penambahan Reduktor Coal dan Aditif CaCO3 pada Reduction-RoastingSekitar 90 dari bijih kromit ditambang dikonversi menjadi ferrochrome oleh industri metalurgi. Industri stainless steel mengkonsumsi sekitar 80 dari ferrochrome yang diproduksi terutama dengan karbon tinggi . Pasir kromit kadar rendah pada penelitian ini merupakan pasir kromit lokal asal Kabupaten Konawe, Sulawesi Selatan. Benefisiasi dilakukan menggunakan teknik Magnetic Separation baik di awal sebelum reduction-roasting maupun di akhir setelah reduction-roasting dan Pre-reduction roasting dilakukan selama 60 menit pada temperatur 1000 C menggunakan variabel penambahan jumlah reduktor sebesar 5 lean coal, stokiometri, 5 excess carbon dan 10 excess carbon serta penambahan jumlah aditif sebesar 5 , 15 , dan 20 . Pengujian XRD dan XRF dilakukan dalam mengarakterisasi sampel awal dan hasil. Rasio Cr/Fe 0,9 dan kadar Cr pada pasir kromit awal 29,3 dalam bentuk Cr2O3 serta kadar Fe 30,9 dalam bentuk Fe2O3. Setelah dilakukan pemisahan magnetik di awal rasio Cr/Fe meningkat menjadi 1,31. Kemudian dilakukan reduksi-roasting dengan hasil bahwa variasi penambahan reduktor dan aditif dapat mempengaruhi perubahan fasa yang terjadi. Dengan seiring penambahan aditif, pemecahan struktur spinel akan semakin baik. Kemudian dilakukan pemisahan magnetic yang dilanjutkan dengan pengujian XRF, rasio Cr/Fe meningkat menjadi 1.530 pada variasi stokiometri reduktor 20 aditif dan 5 excess carbon 20 aditif. Reduktor optimum berada pada stokiometri dan 5 excess carbon sedangkan aditif optimum di 20 . Rasio Cr/Fe setara dengan 60,5 dalam FeCr. Oleh sebab itu, dapat disimpulkan proses benefisiasi berhasil untuk meningkatkan kadar Cr pada pasir kromit kadar rendah. Jenis aditif dan reduktor yang berbeda akan mempengaruhi hasil reduksi-roasting sehingga rasio Cr/Fe yang dihasilkan pun berbeda.Kata kunci: Ferrochrome, pasir krom kadar rendah, pasir krom metallurgical grade, benefisiasi, gravity separation, reduction roasting, magnetic separation

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ABSTRACTThrough Beneficiation Process with the Variation of Reductant Coal and CaCO3 as Additive Dosage on Reduction Roasting Process Approximately 90 of the mined chromite ore is converted to ferrochrome by the metallurgical industry. Chromite sand low grade in this study is a local chromite sand origin Konawe, South Sulawesi. Beneficiation Magnetic Separation is done using techniques well in the beginning before the reduction roasting and in the end after reduction roasting and Pre reduction roasting is done for 60 minutes at a temperature of 1000 C using a variable amount of reductant additions of 5 lean coal, stoichiometric, 5 excess carbon and 10 excess carbon and the addition of an additive at 5 , 15 and 20 . XRD and XRF testing done in characterizing the initial sample and results. The ratio of Cr Fe and Cr content is 0.9 at the beginning of chromite sand in the form of 29.3 Cr2O3 and Fe content of 30.9 in the form of Fe2O3. After magnetic separation at the beginning of the ratio of Cr Fe increased to 1 31. Then do the reduction roasting with the result that the variation of the addition of reductant agents and additives can affect the phase change that occur. With over additive, breaking spinel structure, the better. Then magnetic separation followed by XRF testing, the ratio of Cr Fe increased to 1.530 in the variation of 20 of the stoichiometric reductant additive and 5 20 excess carbon additives. Reductant agents that are in the optimum stoichiometric and 5 excess carbon while the optimum additive at 20 . The ratio of Cr Fe equivalent to 60.5 in FeCr. Therefore, it can be concluded successfully beneficiation process to increase the Cr content at low levels of chromite sand. Type different additives and reductant agents will affect the outcome of reduction roasting so that the ratio of Cr Fe produced any different. "

"ABSTRAKDeposit logam las SMAW 308L dengan variasi ferrit, nitrogen dan fluk basicity dievaluasi untuk meneliti pengaruhnya terhadap kekuatan mekanik dan perilaku korosi. Sifat mekanik diteliti melalui kekuatan tarik pada suhu kamar, charpy impak V-notch dan lateral expansion (LA) di suhu kriogenik -196oC. Polarisasi siklik potensiodinamik dilakukan pada lingkungan NaCl 3.5%w.t untuk mengamati potensial pitting dan hysteresis loop.Peningkatan ferrit dari 2-10FN, secara umum meningkatkan kekuatan logam lasan sebesar 0.5-4.9%. Pengurangan ferrit dari 4FN menjadi 2FN, meningkatkan secara signifikan charpy impak sebesar 21% dan LA sebesar 69%. Lasan dengan kandungan nitrogen yang lebih rendah memiliki charpy impak 10% lebih tinggi dan LA 37% lebih tinggi. Fluk tipe basa memiliki charpy impak 16% lebih besar dan LA 51% lebih besar.Positif hysteresis loop menunjukkan bahwa logam 308L rawan terhadap korosi pitting pada lingkungan NaCl 3,5%wt. Keberadaan ferrit mengurangi ketahanan terhadap korosi sumuran yang ditandai oleh penurunan nilai Epit. Nitrogen yang lebih rendah mengakibatkan Epit menjadi lebih aktif sementara itu Fluk tipe basa memiliki Epit yang lebih noble.Ketangguhan kriogenik dan ketahanan korosi pada logam las 308L dikontrol oleh kandungan ferrit yang rendah, kandungan nitrogen yang rendah dan fluk yang lebih basa. Sementara itu kekuatan mekanik dikontrol oleh kandungan ferrit yang tinggi

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ABSTRACTSMA (Shielded Metal Arc) welds metal 308L with variation in ferrite, nitrogen and flux basicity were evaluated in order to study its influence to mechanical and corrosion behavior. Mechanical behaviors were investigated by using tensile strength at room temperature, charpy impact V-notch and lateral expansion(LA) at cryogenic temperature -196oC. Cyclic polarization potensiodynamic was performed at 3.5% NaCl to observe pitting potential and hysteresis loop.Increment ferrite from 2-10 FN, in general increased 0.5- 4.9% welds strength. Reduction from 4FN to 2 FN had significantly increased charpy impact and LA to 21% and 69% respectively. Weld with lower nitrogen content had 10% higher charpy impact and 37% higher LA. Basic flux significantly increased charpy impact to 16% and LA to 51%.Positive hysteresis loop showed that 308L welds were prone to pitting corrosion at 3.5%w.t chloride solution. Present of ferrite reduced pitting corrosion resistance which indicated by Epit reduction. Lower nitrogen showed more active Epit. Weld with higher flux basicity resulted noble Epit.Cryogenic toughness and corrosion resistance at SMA 308L weld metal are controlled by low ferrite content, low nitrogen content and more basic flux. Meanwhile weld metal strength are controlled by high ferrite content."

"ABSTRAKFerokrom (45-75% Cr dan 35-50% Fe) adalah paduan yang sangat penting dalam pembuatan baja tahan karat karena sifat kekuatan dan ketahanan terhadapa korosi yang tinggi. Ferokrom dibuat dari bijih kromit, sumber kromium yang paling ekonomis untuk di eksploitasi, melalui proses peleburan dengan menggunakan submerged arc furnace. Proses benefisiasi dengan metode roasting adalah proses yang digunakan oleh industri ferokrom dengan rasio Cr/Fe sebagai parameter utama dalam menentukan efisiensi operasi. Semakin tinggi nilai rasio Cr/Fe hasil benefisiasi, semakin tinggi efisiensi yang dicapai saat proses peleburan. Tujuan dari penelirian ini adalah untuk mencapai rasio Cr/Fe tertinggi dengan melakukan beberapa parameter selama proses roasting. Separasi magnet menggunakan kuat magnet 500 gauss dilakukan terhadap pasir kromit kadar rendah.Roasting dilakukan pada temperatur 800, 1000 dan 1200 oC selama 30, 60, dan 90 menit. 100 gram produk non magnet hasil separasi magnet awal digunakan sebagai material utama, 30,6 gram batubara sebagai reduktor dan 10 gram CaCO3 sebagai flux. Separasi magnet dilakukan untuk memisahkan senyawa yang bersifat magnet hasil roasting. Respon dari roasting di lihat dengan X-ray diffraction (XRD), sedangkan efek separasi magnet dievaluasi dengan X-ray fluorescence (XRF). Hasil penelitian ini menunjukkan rasio Cr/Fe tertinggi adalah 1,54 pada roasting 1000 oC selama 60 menit. Terlihat bahwa roasting dapat memisahkan senyawa FeO dari struktur spinel dan separasi magnet dapat mengurangi unsur besi untuk meningkatkan rasio Cr/Fe.

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ABSTRACTFerrochromium (45-70 % Cr and 35-50% Fe) is a vital alloy mostly used for the production of stainless steel due to its high strength and corrosion resistance. It is produced from chromite ore, the only economically exploitable resource of chromium, through carbo-thermic smelting in submerged arc furnaces. The beneficiation-roasting process of chromite is currently applied as ferrochromium industrial production with the Cr/Fe ratio as the main parameter to determine the efficiency of the operation. The higher Cr/Fe ratio obtained during beneficiation-roasting process, the higher efficiency of smelting would be achieved. The objective of this research is to get the highest Cr/Fe ratio with conducting several parameters during roasting operation. Magnetic separation using 500 gauss of the magnetic intensity was carried out to the low grade chromite ore.Roasting was conducted at 800, 1000 and 1200 oC for 30, 60 and 90 minutes with the 100 grams of non-magnetic product as the main material, 30.6 gram of coal as reductor and 10 gram of CaCO3 as flux. Afterwards, magnetic separation was reconducted to separate the magnetic constituent. The roasting response was observed by X-ray diffraction (XRD), while the effect of magnetic separation was determined by X-ray fluorescence (XRF). The results showed that the highest Cr/Fe ratio is 1.54, achieved after roasting at 1000oC for 60 minutes. It clearly indicates that roasting process has successfully released the FeO from Spinel Crystal and separation using magnet can decrease the iron constituent in chromite to enhance the Cr/Fe ratio."

"[ABSTRAKLogam ferromangan adalah salah satu unsur paduan penting pada bajauntuk meningkatkan sifat mekanis, ketahanan aus, dan kekerasannya. Bentukferromangan (FeMn) telah diatur dalam standard ASTM dengan kadar minimalsebesar 75% Mangan (Mn). Tujuan penelitian ini adalah pembuatan logam FeMndengan kandungan minimal 60%Mn dari bijih mangan lokal dan mempelajari efekdari basasitas terak yang dipengaruhi oleh penambahan kapur sebagai zat aditifdalam proses pembuatan ferromangan terhadap jumlah produk ferromangan yangdihasilkan dan konsumsi energi yang dibutuhkan dalam proses tersebut.Dalam penelitian ini digunakan bijih mangan lokal kadar menengah daridaerah Jember-Jawa Timur 39.38 Mn ? 2.89 Fe ? 26.58 SiO2 (Medium Grade Ore)dengan teknologi Mini Sub-merged Arc Furnace (SAF) di UPT BPM LIPI,Lampung. Setiap satu kali proses, digunakan 30 kg bijih mangan (Ø ±30mm), 7.5kg kokas, dan jumlah batu kapur yang bervariasi, yaitu; 8, 10, 12, dan 14 kg.Proses peleburan berlangsung pada temperatur 1200-1500 oC. Kemudian hasilakan dianalisa dengan menggunakan XRF (X-Ray Fluoroscence), XRD (X-RayDiffraction), AAS (Atomic Absorbtion Spectrometry), dan Proksimat.Hasil penelitian menunjukan bahwa dengan meningkatnya basasitas terak(dari 0.32 hingga 0.76) akan meningkatkan jumlah produk ferromangan hingga 8.2kg FeMn, kemudian memaksimalkan kadar % mangan yang tereduksi pada logamhingga mencapai komposisi kimia yang optimal (78,13 Mn-12,65 Fe-8.93 Si),menekan konsumsi energi hingga 9.8 kwh/kg ferromangan, menekan angkakonsumsi elektroda, dan menghasilkan prosentase efisiensi proses berupa % yieldyang cukup tinggi yakni sebesar 58.61%. Hasil lain yang menunjang prosespengolahan ferromangan dengan meningkatnya hasil basasitas terak adalahtercapainya suhu reaksi yang tinggi yakni sebesar 15940C sehingga membuatreduksi oksida mangan pada terak menjadi mangan pada logam semakin baik,kemudian jumlah terak juga dapat ditekan. Selanjutnya secara tinjauan aspekekonomi dari keempat kali proses penelitian, maka didapatkan hasil yang palingmenguntungkan sebesar Rp 5.731,-/proses.ABSTRACTFerromanganese metal is an important alloying element in steel productionindustry used to maximize its mechanical properties such as wear resistance andhardness. The most common form of ferromanganese according to ASTM standardcontain min.75%Mn and max.25%Fe inside the product. The target of this researchis to obtain ferromanganese metal with min.60%Mn using medium grademanganese ore (39.38 Mn ? 2.89 Fe ? 26.58 SiO2) from Jember district - East Java,yet the effect of its slag basicity will also support the most optimum result. This kindof basicity will determined by the amount of limestone as fluxing agent which addedto the furnace. Moreover, this study will focus to the effect of its slag basicity on thenumber of ferromanganese product and the amoung of energy consumption.This study was taking place at UPT BPM LIPI Lampung, Sumatera. Usingtheir Mini Sub-merged Arc Furnace (SAF) the process began without anybeneficiation processs for its raw material. Manganese ore Ø ±30mm, cokes, andlimestones were added at the same time to the SAF and melted at 1200-1450 oC.Processes were repeated 4 times with each process using 30 kg manganese ore, 7.5kg cokes, and limestones which varied from 8, 10, 12, and 14 kg. Validity of thisstudy supported by the chemical analysis which took place before and afterreduction process using some tools such as XRF (X-Ray Fluoroscence), XRD (XRayDiffraction), AAS (Atomic Absorbtion Spectrometry), and Proxymate analysis.The result of this research showed an increasing trend in product?s qualityas the slag basicity and the amount of limestone increased. As the slag basicityincrease, the number of ferromanganese metal products were also increased until8.2 kg FeMn and the amount of manganese element in metal phase also showed themost optimum chemical composition of ferromanganese metal (78,13 Mn-12,65 Fe-8.93 Si). Furthermore, the energy consumption can be reduced until 9.8kwh/kg FeMn as well as the electrodes consumption and also the efficiencypercentage or % yield process can be increased up to 58.61%. Other parameterswhich used to support these 4-times-research plan was the temperature level whichturned out to be as high as 15940C and helped the reduction process of manganeseoxide into manganese metal became easier. Not only to obtain more manganesecontent in metal phase, but also this level of reduction temperature can reduced theamount of slag. Finally, in addition to support the optimum data, economic analysisalso showed that this composition was the most profitable process with Rp 5.731,-/process as its profit., Ferromanganese metal is an important alloying element in steel productionindustry used to maximize its mechanical properties such as wear resistance andhardness. The most common form of ferromanganese according to ASTM standardcontain min.75%Mn and max.25%Fe inside the product. The target of this researchis to obtain ferromanganese metal with min.60%Mn using medium grademanganese ore (39.38 Mn – 2.89 Fe – 26.58 SiO2) from Jember district - East Java,yet the effect of its slag basicity will also support the most optimum result. This kindof basicity will determined by the amount of limestone as fluxing agent which addedto the furnace. Moreover, this study will focus to the effect of its slag basicity on thenumber of ferromanganese product and the amoung of energy consumption.This study was taking place at UPT BPM LIPI Lampung, Sumatera. Usingtheir Mini Sub-merged Arc Furnace (SAF) the process began without anybeneficiation processs for its raw material. Manganese ore Ø ±30mm, cokes, andlimestones were added at the same time to the SAF and melted at 1200-1450 oC.Processes were repeated 4 times with each process using 30 kg manganese ore, 7.5kg cokes, and limestones which varied from 8, 10, 12, and 14 kg. Validity of thisstudy supported by the chemical analysis which took place before and afterreduction process using some tools such as XRF (X-Ray Fluoroscence), XRD (XRayDiffraction), AAS (Atomic Absorbtion Spectrometry), and Proxymate analysis.The result of this research showed an increasing trend in product’s qualityas the slag basicity and the amount of limestone increased. As the slag basicityincrease, the number of ferromanganese metal products were also increased until8.2 kg FeMn and the amount of manganese element in metal phase also showed themost optimum chemical composition of ferromanganese metal (78,13 Mn-12,65 Fe-8.93 Si). Furthermore, the energy consumption can be reduced until 9.8kwh/kg FeMn as well as the electrodes consumption and also the efficiencypercentage or % yield process can be increased up to 58.61%. Other parameterswhich used to support these 4-times-research plan was the temperature level whichturned out to be as high as 15940C and helped the reduction process of manganeseoxide into manganese metal became easier. Not only to obtain more manganesecontent in metal phase, but also this level of reduction temperature can reduced theamount of slag. Finally, in addition to support the optimum data, economic analysisalso showed that this composition was the most profitable process with Rp 5.731,-/process as its profit.]"

"Cadangan bijih mangan kadar rendah di Indonesia cukup besar, namun cadangan bijih mangan tersebut tidak dapat dimanfaatkan secara optimal karena rendahnya rasio Mn/Fe.Sehingga diperlukan penelitian untuk mempelajari metode benefiasi guna meningkatkan rasio Mn/Fe, menggunakan bijih mangan kadar rendah dari Kabupaten Tanggamus (MnO=15.30%, rasio=0.91) dan kabupaten Jember (MnO=28.66%, rasio=1.39) supaya bisa dijadikan bahan baku dalam pembuatan FeMn menggunakan SAF.Penelitian benefisiasi bijih mangan kadar rendah dimulai dengan melakukan fraksinasi untuk mendapatkan ukuran butir 841-420 μm, 420-250 μm dan 250-177 μm kemudian dilakukan proses pemisahan gravitasi untuk menghasilkan concentrate dan tailing yang akan digunakan sebagai bahan baku untuk reduction reduction roasting. Proses reduction roasting dilakukan dengan variasti suhu 500°C, 700°C dan 900°C serta variasi waktu reduction roasting 30, 60, 90 dan 120 menit dan kemudian dilakukan proses pemisahan secara magnetic. Material non magnetik yang menghasilkan peningkatan rasio Mn/Fe paling optimum akan dilakukan proses briketisasi untuk digunakan sebagai bahan baku pembuatan FeMn menggunakan SAF.Pengaruh variasi temperatur dan waktu reduction roasting memberikan hasil rasio Mn/Fe optimum 6.11, pada partikel non magnetik ukuran 841-420 μm dengan suhu reduction roasting 700°C selama 60 menit. Proses reduction roasting juga menyebabkan munculnya fase baru seperti Hausmanite (Mn3O4), Manganosite (MnO), Fayalite (Fe2SiO4) dan Phlogopite (KMg3(AlSi3O10(OH)2), akibat proses perubahan fase pada bijih mangan. Fase mineral tersebut muncul pada reduction roasting variasi waktu 60 menit, 90 menit dan 120 menit, serta muncul pada variasi suhu 500°C, 700°C dan 900°C.Pada pengujian dalam SAF digunakan basisitas berdasarkan stoichiometri dengan nilai 1.17, 1.32, 1.15 dan basisitas referensi hasil penelitian Bobby et al, 2015, dengan nilai 0.7. Penggunaan basisitas 0.7 menghasilkan kenaikan berat metal dan menurunkan berat terak pada saat diproses dalam SAF. Selain itu basisitas stoichiometry hanya menghasilkan ferromangan dengan Mn=35.47% dan basisitas referensi 0.7 menghasilkan Ferromangan dengan Mn=60%.Hasil penelitian ini menunjukkan bahwa peningkatan rasio menggunakan benefisiasi bisa mencapai rasio 6.11. Sedangkan proses pembuatan FeMn dengan menggunakan bijih mangan kadar rendah pada submerged arc furnace bisa menghasilkan kadar Mn 60% dengan kontrol pada basisitas untuk mengurangi volume terak, meningkatkan berat logam dan menaikkan kadar Mn.

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Low grade manganese ore reserves in Indonesia is quite large, but manganese ore reserves can not be used optimally because of the low ratio of Mn / Fe.In that case, research is needed to study the methods of benefiasiation to increase the ratio of Mn / Fe, using low grade manganese ore from Tanggamus ( MnO = 15.30% ratio = 0.91) and Jember (MnO = 28.66%, ratio = 1.39) that can be used as raw material in the manufacture of FeMn using SAF.

Research for beneficiation of low grade manganese ore started by fractionation to obtain the grain size of 841-420 μm, 420-250 μm dan 250-177 μm then performed meja getar process to produce the concentrate and tailings to be used as ingredients raw for reduction roasting. Reduction roasting variety process carried out with a temperatur of 500 °C, 700 °C and 900 °C and roasting time variation of 30, 60, 90 and 120 minutes and then a magnetic separation process. Non-magnetic material that produces an increase in the most optimum ratio of Mn/Fe will be used into bricketing process as raw material for FeMn using SAF.

The effect of variation of temperatur and roasting time results ratio of Mn/Fe optimum 6.11, on a non-magnetic particle size of 841-420 μm with a roasting temperature of 700 °C for 60 minutes. Roasting also cause new phase occurensces such as Hausmanite (Mn3O4), Manganosite (MnO), Fayalite (Fe2SiO4) and Phlogopite (KMg3(AlSi3O10(OH)2), due to the process of phase changes in manganese ore. Mineral mineral appeared on roasting with time variations 60 minutes, 90 minutes and 120 minutes, as well as appearing on the variation in temperatur of 500 °C, 700 °C and 900 °C.

On testing in the SAF used basicity based stoichiometri with a value of 1.17, 1.32, 1.15 and reference basicity 0.7 based on the Bobby et al, 2015 reserach. Influence of basicity resulted in an increase of weight of metal and decrease the weight of slag during processing in the SAF. In addition basicity stoichiometry produces only ferromangan with Mn = 35.47% and reference basicity 0.7 generate Ferromangan with Mn = 60%.

The results of this study showed that increasing the ratio of Mn/Fe using beneficiation could reach a ratio 6.11. While the process of making FeMn using low grade manganese ore at Submerged arc furnace can produce 60% Mn grade with controls on basicity to reduce the volume of slag, improve and raise the level of heavy metals Mn."

"Asam 12-hidroksistearat (12-HSA) sebagai bahan baku gemuk pelumas saat ini masih diimpor oleh Indonesia. Sedangkan, data mencatat potensi minyak jarak Indonesia masih sangat besar untuk dikembangkan. Kandungan asam risinoleatnya yang tinggi dapat disintesis menjadi 12-HSA. Pada penelitian ini dilakukan hidrogenasi minyak jarak menjadi hydrogenated castor oil sebagai bahan baku 12-HSA dengan menggunakan katalis nikel dan support zeolit alam. Katalis dipreparasi dengan metode presipitasi menggunakan prekursor klorida. Suhu hidrogenasi divariasikan dari 110-190oC. Hidrogenasi direaksikan pada tekanan rendah, yaitu 2 dan 3 atm. Tingkat keberhasilan hidrogenasi ditentukan dari jumlah pemutusan ikatan rangkap yang ditunjukkan oleh penurunan bilangan iodin dan kenaikan titik tuang. Penelitian ini berhasil menurunkan bilangan iodin minyak jarak dari 81 menjadi 61 dan menaikkan titik tuangnya dari -10°C menjadi -4°C. Produk yang terbaik didapat pada hidrogenasi dengan suhu 150°C dan tekanan 3 atm dimana konversinya mencapai 24,84%.

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12-hydroxystearic acid (12-HSA) as a raw material for grease is still imported by Indonesia. Meanwhile, the data noted potential of castor oil in Indonesia is still very huge to be developed. Its high ricinoleat acid content can be synthesized into 12-HSA. In this research, we carried out the hydrogenation of castor oil to be hydrogenated castor oil as raw material of 12-HSA using nickel catalyst and natural zeolite support. The catalysts were prepared by precipitation method using chloride precursor. Hydrogenation temperature was varied from 110-190°C. Hydrogenation reacted at low pressure approximately 2 and 3 atm. The success rate of hydrogenation is determined from the termination of the double bond indicated by iodine value decreasing and pour point increasing. The research was successful in reducing the iodine value of castor oil from 81 to 61 and raising the pour point from -10°C to -4°C. The best product obtained in hydrogenation with 150°C of temperature and 3 atm of pressure where the conversion reached 24,84%."

"Mineral mangan merupakan salah satu mineral yang paling banyak ditemui di kerak bumi. Sebagian besar produksi mangan dan paduannya di dunia saat ini diserap oleh industri baja. Ferromangan merupakan salah satu logam paduan dengan kandungan mangan yang sangat tinggi, yaitu sekitar 65 - 90%. Sebanyak 90%, ferromangan digunakan untuk menambahkan unsur mangan kedalam material baja untuk memperbaiki sifat-sifat mekanik dari material baja, seperti kekuatan, hardenability, dan ketahanan terhadap aus. Penelitian ini bertujuan untuk mengetahui pengaruh penambahan kadar kokas terhadap keefisienan proses reduksi bijih mangan lokal kadar menengah menjadi produk ferromangan. Proses reduksi dilakukan pada tungku submerged arc furnace tiga fasa dengan kapasitas 100 Kg/Batch dilengkapi dengan tiga buah elektroda grafit. Setiap percobaan menggunakan 30 Kg bijih mangan lokal, 12 Kg limestone, dan kadar kokas yang bervariasi, yaitu 5,5 Kg (18,33%), 7,5 Kg (25,00%), 9,5 Kg (31,67%), dan 11,5 Kg (38,33%). Hasil penelitian menunjukkan bahwa kuantitas dan kualitas produk ferromangan yang dihasilkan meningkat seiring dengan bertambahnya kadar kokas yang digunakan. Dimana kandungan mangan pada ferromangan dan massa/yield produk ferromangan cenderung meningkat. Kandungan mangan pada produk ferromangan tertinggi sebesar 78% pada pengujian menggunakan kokas sebanyak 7,5 Kg (25,00%). Sedangkan massa produk ferromangan tertinggi terdapat pada pengujian dengan menggunakan kokas sebanyak 9,5 Kg (31,67%), yaitu 12,8 Kg. Dan pada penggunaan energi selama proses berlangsung cenderung menurun dengan penambahan kokas, dimana penggunaan energi terendah selama proses reduksi berlangsung pada pengujian menggunakan kokas sebanyak 9,5 Kg (31,67%) sebesar 7,03 KWh/Kg. Namun konsumsi elektroda cenderung meningkat. Sehingga konsumsi elektroda grafit terendah pada saat menggunakan kokas 5,5 Kg (18,33%), yaitu sebesar 0,75 Kg. Berdasarkan aspek ekonomi, pengujian dengan keuntungan tertinggi terdapat pada pengujian menggunakan kokas sebanyak 9,5 Kg (31,67%) yaitu sebesar Rp 62.565 pada tiap satu kali pengujian.

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Manganese is one of the most common minerals in the earth’s crust.Manganese plays an important role in the development of various steel making processes and its continuing importance is indicated by the fact that about 90% of all manganese alloys consumed annually goes into steel production as an alloying element in the form of ferromanganese. Ferromanganese is one of the metal alloys with a high content of manganese, which is about 65 - 90%. Manganese has four functions to steel such as desulphurizing agent, deoxidation agent, enhancing hardness, and wear resistance. This research, studies have been made to obtain the most optimum raw material composition to produce ferromanganese metal based on local medium grade manganese ore with various amount of cokes as its main variable. The process is conducted four times by smelting manganese ore into ferromanganese metal in mini submerged arc furnace (SAF) technology using three graphite electrodes. The process begin with using 30 kg of medium grade manganese ore from Jember, East Jawa-Indonesia, 12 kg of limestone as its fluxing agent, and various number of cokes from 5,5 kg (18,33%), 7,5 kg (25%), 9,5 kg (31,67%), and 11,5 kg (38,33%). Influence of various amount of cokes being used in this study have been investigated. The experiment conducted by increasing number of cokes carried out good results. Higher consumption of cokes will produce bigger number of ferromanganese metal and also the manganese content inside it. The most optimum composition of cokes shown by this study is 9,5 kg (31,67%), producing the biggest number of product at 12,8 kg of ferromanganese and consuming the least energi at 7,03 kwh/kg FeMn. The other result also showed that adding 7,5 kg (25%) of cokes will produce 78% manganese content inside the metal which was the highest manganese content. However, with an increase of cokes, the electrode consumption will also increase. The experiment with 5,5 kg (18,33%) of cokes carried out the least electrodes consumption at 0,75 kg/process. Moreover, to support the optimum raw material composition, economic evaluation has been conducted. The biggest profit is Rp 62.565,-/process for 9,5 kg (31,67%) of cokes.

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"[ABSTRAKMangan merupakan logam yang digunakan untuk berbagai macam kebutuhan seperti untuk campuran logam agar menghasilkan baja dalam industri baja. Kebutuhan bijih mangan juga meningkat seiring dengan peningkatan teknologi dan kebutuhan akan mangan tersebut. Pada penelitian ini akan dilakukan proses pembuatan ferromangan dari bahan baku bijih mangan lokal dengan menggunakan submerged arc furnace (SAF). Proses peleburan dilakukan dengan menggunakan 30kg bijih mangan, 12kg batu kapur, dan jumlah kokas serta batu bara yang bervariasi, yaitu 0%, 25%, 50%, 75%, dan 100%. Kemudian, analisa karaktrisasi akan dilakukan untuk mengetahui kualitas produk ferromangan yang dihasilkan, yaitu analisa XRF (X-Ray Fluoroscence), XRD (X-Ray Diffraction) untuk mengecek kadar mangan dan kadar slag, analisa masa selama proses produksi, dan analisa jumlah pemakaian energi selama proses produksi.Hasil penelitian menunjukkan dengan peningkatan kadar kokas dibandingkan kadar batu bara dapat meningkatkan kualitas maupun kuantitas produk ferromangan. Dengan penggunaan 9.5kg (100%) coke akan menghasilkan massa/yield tertinggi yaitu 12.8kg / 96.24% karena kokas memiliki unsur yang lebih baik daripada batu bara sehingga proses reduksi dapat menjadi optimal. Selanjutnya, kandungan mangan pada produk ferromangan tertinggi saat penggunaan 9.5kg (100%) coke sebesar 75.19% Mn karena kokas memiliki kandungan unsur pengotor yang lebih sedikit dibandingkan dengan batu bara sehingga proses reduksi berlangsung dengan optimal. Kemudian, konsumsi energy terendah saat penggunaan 9.5kg (100%) coke sebesar 7.03KWh/kg karena kokas memiliki kandungan pengotor yang sedikit, salah satu contohnya volatile matter, jika kandungan unsur tersebut besar maka konsumsi energi akan bertambah. Sedangkan kandungan fosfor dan sulfur terendah pada produk ferromangan ketika penggunaan 9.5 kg (100%) coke, yaitu fosfor dibawah 0.001% dan sulfur 0.18%. Pengaruh kandungan tersebut berasal dari reduktor yang digunakan, kokas memiliki kandungan phosphorus dan sulphur yang lebih rendah jika dibandingkan dengan kokas. Phosphorus dapat membuat rapuh logam karena adanya perbedaan kekerasan, kekuatan, dan keuletannya. Sedangkan sulphur dapat membuat rapuh logam pada saat temperature tempa, sehingga kemampuan tempanya akan menurun. Selain itu berdasarkan aspek ekonomi, diperoleh hasil yang memilik keuntungan tertinggi sebesar Rp62,565 dengan penggunaanreduktor sebanyak 9.5kg (100%) coke dan 0kg (0%) coal.ABSTRACTManganese mineral is one of the metal element which are used in common to produce alloy steel product. Manganese element is important to enhance steel properties such as wear resistance and hardness. Due to high demand of alloy steel, the production of ferromanganese products are also increase. This phenomena leaded to a large number of manganese ore supply. In this present study, the ferromanganese production will be conducted in mini submerged arc furnace (SAF) technology. The process began with 30 kg medium grade manganese ore from Jember, East Java-Indonesia, 12 kg limestone as its fluxing agent, and with the main variable of mixed reductor from 0%, 25%, 50%, and 100% of cokes and coal as its balance. Along the process, chemical analysis also conducted with some tools to obtain an accurate data of chemical compositions within the raw materials, slag, and ferromanganese product. These chemical analysis were conducted by XRF, XRD, and Proximate analysis. Furthermore, not only the chemical composition but also the number of electricity in each process were calculated to obtain the most efficient process.The result of this research showed an increasing trend in ferromanganese quality and quantity with a large number of cokes. Instead of coal, cokes are more effective as a reductor agent in this process. This study showed that with 9.5 kg of cokes (100%) the reduction process of ferromanganese will produce 12.8 kg of ferromanganese metal, 75.19% of manganese content, 96.24% of yield ratio, and least number of energy consumption 7.03 kwh/kg ferromanganese product. One of the reasons to support this result is because cokes have lesser number of impurities than in coal such as volatile matter. The amount of phosphor and sulfur content in ferromanganese metal also can be reduced to < 0.001% P and 0.18% S by using 100% cokes as its reductor. These parameters are important because with small number of phosphor and sulfur content the metal will become tougher and hinder the negative effect of short red hardness in metal during further forming activity. The other reason to support the effectiveness of using 100% cokes as the reductor instead of mixing with coal is the amount of profit for each process which is turned to be the highest profit number compare to other mixing composition, it is Rp 62.565,-/process., Manganese mineral is one of the metal element which are used in common to produce alloy steel product. Manganese element is important to enhance steel properties such as wear resistance and hardness. Due to high demand of alloy steel, the production of ferromanganese products are also increase. This phenomena leaded to a large number of manganese ore supply. In this present study, the ferromanganese production will be conducted in mini submerged arc furnace (SAF) technology. The process began with 30 kg medium grade manganese ore from Jember, East Java-Indonesia, 12 kg limestone as its fluxing agent, and with the main variable of mixed reductor from 0%, 25%, 50%, and 100% of cokes and coal as its balance. Along the process, chemical analysis also conducted with some tools to obtain an accurate data of chemical compositions within the raw materials, slag, and ferromanganese product. These chemical analysis were conducted by XRF, XRD, and Proximate analysis. Furthermore, not only the chemical composition but also the number of electricity in each process were calculated to obtain the most efficient process.The result of this research showed an increasing trend in ferromanganese quality and quantity with a large number of cokes. Instead of coal, cokes are more effective as a reductor agent in this process. This study showed that with 9.5 kg of cokes (100%) the reduction process of ferromanganese will produce 12.8 kg of ferromanganese metal, 75.19% of manganese content, 96.24% of yield ratio, and least number of energy consumption 7.03 kwh/kg ferromanganese product. One of the reasons to support this result is because cokes have lesser number of impurities than in coal such as volatile matter. The amount of phosphor and sulfur content in ferromanganese metal also can be reduced to < 0.001% P and 0.18% S by using 100% cokes as its reductor. These parameters are important because with small number of phosphor and sulfur content the metal will become tougher and hinder the negative effect of short red hardness in metal during further forming activity. The other reason to support the effectiveness of using 100% cokes as the reductor instead of mixing with coal is the amount of profit for each process which is turned to be the highest profit number compare to other mixing composition, it is Rp 62.565,-/process.]"