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Abstrak :
ABSTRAK Pelindian mangan dari bijih mangan kadar rendah telah berhasil dilakukan menggunakan larutan sulfat. Pada percobaan ini, bijih mangan dipanggang dengan arang kayu sebagi reduktor pada 700 oC selama 120 menit. Kemudian kalsin hasil pemanggangan dilindi menggunakan larutan asam sulfat. Parameter proses pelindian yang diamati meliputi pengaruh kecepatan pengadukan, konsentrasi asam, temperatur, waktu dan persen padatan terhadap mangan terekstrak. Hasil optimum didapat pada proses pelindian dengan konsentrasi 12% H2SO4, kecepatan pengadukan 400 rpm, rasio padatan 1:10, dan temperatur 75 oC selama 3 jam dengan mangan terekstrak sebesar 84,61%. Kinetika reaksi pelindian mangan dalam asam sulfat dikendalikan oleh proses difusi dengan nilai energi aktivasi sebesar 4,88 KJ/mol.

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ABSTRACT The leaching of manganese from low-grade manganese ores in aqueous sulfuric acid solution was investigated. In this study, manganese ores were prepared by reduction roasting using charcoal as a reductant at 700 oC for 120 min. The roasted samples were then leached with aqueous sulfuric acid solution. The effects of agitation rate, sulfuric acid concentration, solid/liquid mass ratio, leaching temperature and leaching time on the leaching efficiency of manganese were studied. The optimal leaching conditions are achieved at 12% H2SO4, agitation rate of 400 rpm, solid/liquid mass ratio of 1:10, and the leaching temperature of 75 oC for 180 min. Under the optimal condition, the leaching efficiency of manganese can reach 84.61%. The kinetical reaction of manganese dissolution in aqueous sulfuric acid solution was found to be controlled by diffusion process with activation energy is 4.88 KJ/mol.

Abstrak :
ABSTRAK
Sekitar 90% bijih mangan di dunia digunakan untuk pembuatan ferromangan dan ferrosilicomangan sebagai material paduan dalam proses steel making. Penambahan unsur mangan dalam wujud paduan ferromangan pada proses steel making mampu meningkatkan kekerasan dan ketangguhan baja. Ferromangan diperoleh dari pengolahan bijih mangan metallurgical grade dengan proses peleburan. Bijih mangan kadar rendah, melalui penelitian sebelumnya oleh Hendri (2015) dan Noegroho (2016), tidak ekonomis untuk dilebur menjadi ferromangan 􀁇􀁈􀁑􀁊􀁄􀁑􀀃􀀰􀁑􀀃􀂕􀀙􀀓􀀈􀀃􀁖􀁈􀁋􀁌􀁑􀁊􀁊􀁄􀀃􀁅􀁌􀁍􀁌􀁋􀀃 mangan kadar rendah harus dibenefisiasi terlebih dahulu untuk meningkatkan kadar mangan dan rasio Mn/Fe dalam bijih. Bijih mangan kadar rendah pada penelitian ini merupakan bijih mangan lokal asal Lampung dan Jawa Timur. Benefisiasi dilakukan menggunakan teknik gravity separation dan reduction roasting selama 30 menit menggunakan 20% batu bara dilanjutkan magnetic separation pada medan magnet ±500 gauss. Bijih mangan dihaluskan ke dalam ukuran -20+40, -40+60, dan -60+80 mesh dan temperatur reduction roasting divariasikan pada 500oC, 700oC, dan 900oC. Pengujian XRD dan XRF dilakukan dalam mengarakterisasi sampel awal dan hasil. Rasio Mn/Fe dan kadar mangan pada bijih asal Lampung masing-masing sebesar 0,90 dan 7,83% sementara pada bijih asal Jawa Timur masing-masing sebesar 1,356 dan 18,52%. Setelah dibenefisiasi, hasil terbaik dari proses gravity separation pada bijih Lampung tercapai pada rasio Mn/Fe 0,95 dengan kadar Mn 9,4% pada 89,75% recovery berat sementara pada bijih Jawa Timur diperoleh pada rasio Mn/Fe 3,32 dengan kadar mangan 40,48% pada 2,09% recovery berat. Selanjutnya, hasil terbaik dari reduction roasting dilanjutkan magnetic separation pada bijih Lampung diperoleh pada rasio Mn/Fe 1,96 dan kadar mangan 6,81% pada 36 wt% recovery, sementara pada bijih Jawa Timur, tercapai pada rasio Mn/Fe 3,99 dan kadar mangan 34,31% pada 44 wt% recovery.

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ABSTRACT
About 90% of manganese ore is utilized for ferromanganese and ferrosilicomanganese production as alloying metal in the steel making process. The addition of manganese in the form of ferromanganese to the steel making process is able to increase hardness and toughness of steel. Ferromanganese is obtained from the metallurgical grade manganese ore processing through the smelting process. Low grade manganese ore, according to the previous research from Hendri (2015) and Noegroho (2016), was not economic for direct smelting to obtain ferromanganese with Mn 􀂕􀀙􀀓􀀈􀀑􀀃 Therefore, low grade manganese ore must be beneficiate first to enhance the manganese grade and its ratio. Low grade manganese ore in this research are a local ore from Lampung and East Java. The steps on the beneficiation process are including gravity separation and reduction roasting for 30 minutes using 20% of coal followed by magnetic separation at the magnetic intensity of ±500 Gauss. The particle size was reduced into -20+40, - 40+60, and -60+80 mesh and the temperature of reduction roasting was varied at 500oC, 700oC, and 900oC. XRD and XRF testing was conducted for the characterization of ore and the sample results. Mn/Fe ratio and manganese content in Lampung ore is respectively 0.9 and 7.83%, while in East Java ore is respectively 1.356 and 18.52%. After beneficiation, the best results from gravity separation of Lampung ore was obtained at 0.95 of Mn/Fe ratio and 9.4% of manganese content at 89.75% of weight recovery, while in East Java ore was obtained at 3.32 of Mn/Fe ratio and 40.48% of manganese content at 2.09% of weight recovery. Then, the best results of reduction roasting followed by magnetic separation of Lampung ore was obtained at 1.96 of Mn/Fe ratio and 6.81% of manganese content at 36% of weight recovery, while in East Java ore was obtained at 3.99 of Mn/Fe ratio and 34.31% of manganese content at 44% weight recovery.

Abstrak :
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. ......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.

Abstrak :
[ABSTRAK
Potensi cadangan bijih mangan di Indonesia cukup besar, namun terdapat di berbagai lokasi yang tersebar di seluruh Indonesia. Komoditi ini menjadi bahan baku yang tidak tergantikan di industri baja dunia. Ferromangan (FeMn) merupakan logam paduan dengan komposisi 75% Mangan (Mn) dan 25% besi (Fe) yang umumnya digunakan pada proses peleburan besi/baja guna memperbaiki sifak-sifat mekanik dari produk yang dihasilkan. Penelitian ini dilakukan untuk mempelajari pengaruh proses pencanpuran bijih Mn kadar rendah (LG) yang berasal dari Kab. Tanggamus, Lampung (16,3 %Mn-19,2 %Fe-20,2 %Si) dengan bijih Mn kadar menengah (MG) yang berasal dari Jember, Jawa Timur (27,7 %Mn-4,4 %Fe-14,7%Si) sebagai bahan baku untuk pembuatan logam FeMn dengan kandungan minimal sebesar 50 %Mn. Penelitian ini dilakukan sebanyak 5 kali percobaan dengan variasi pada campuran bijih Mn yaitu [1] 25 %LG+75 %MG, [2] 50 %LG+50 %MG, [3] 75 %LG+25 %MG, [4] 100 %LG, dan [5] 100 %MG. Bijih mangan diproses menggunakan Submerged Arc Furnace (SAF) dengan input berupa bijih Mn sebagai bahan baku utama, kokas sebagai reduktor, dan kapur sebagai aditif. Ketiga bahan baku tersebut dilebur hingga mencapai temperatur 1500 oC. Untuk mengetahui kualitas bahan baku dan produk FeMn yang dihasilkan, dilakukan analisa seperti XRF (X-Ray Fluoroscence), XRD (X-Ray Diffraction), AAS (Atomic Absorbtion Spectrometry), dan Proksimat. Dari hasil penelitian didapatkan bahwa untuk percobaan [1] diperoleh logam FeMn sebanyak 5,2 Kg dengan kadar 54,05 %Mn, percobaan [2] diperoleh logam FeMn sebanyak 4,75 Kg dengan kadar 50,03 %Mn, percobaan [3] diperoleh logam FeMn sebanyak 4,6 Kg dengan kadar 36,44 %Mn, percobaan [4] diperoleh logam FeMn sebanyak 4,3 Kg dengan kadar 31,13 %Mn, dan percobaan [5] diperoleh logam FeMn sebanyak 12,8 Kg dengan kadar 75,19 %Mn. Pengaruh dari proses pencampuran (Mn-blend) dalam pembuatan ferromangan ini adalah semakin banyak komposisi bijih Mn kadar menengah (MG) yang digunakan, menyebabkan (a) semakin banyaknya kokas dan semakin berkurangnya kapur yang dibutuhkan, (b) meningkatnya yield, jumlah produk, serta kandungan persentase Mn dari FeMn yang dihasilkan, dan (c) semakin rendahnya konsumsi energi yang dibutuhkan. ABSTRACT
The potential reserve of manganese ore in Indonesia is very large, but it was located in different locations spread throughout Indonesia. Manganese ore is one of raw material in producing ferromanganese that is not replaceable in the world steel industry. Ferromanganese (FeMn) is an alloying metal that contained of 75% Manganese (Mn) and 25% Iron (Fe) which is generally used in the process of iron/steel making to improve its mechanical properties. In this experiment, ferromanganese production was conducted by blending two kinds of manganese ore, that was low grade Mn ore (LG) which derived from Tanggamus, Lampung (16,3 %Mn-19,2 %Fe-20,2 %Si) and medium grade Mn ore (MG) which derived from Jember, East Java (27,7 %Mn-4,4 %Fe-14,7 %Si), to obtain ferromanganese with a minimum content of 50 %Mn. The composition of Mn-blend in this experiment was [1] 25 %LG+75 %MG, [2] 50 %LG+50 %MG, [3] 75 %LG+25 %MG, [4] 100 %LG, and [5] 100 %MG. This mixed manganese ore was processed by using Submerged Arc Furnace (SAF). Cokes and limestone was added into the furnace as reductant and flux agent, respectively. Those raw materials are smelted until 1500 °C. To determine the composition of raw materials and the product of FeMn, analysis such as XRF (X-Ray Fluorescence), XRD (XRay Diffraction), AAS (Atomic Absorption Spectrometry), and proximate have to be done. From each composition of Mn-blend above in this experiment, it was obtained that [1] 5,2 Kg of FeMn with 54,05 %Mn, [2] 4,75 Kg of FeMn with 50,03 %Mn, [3] 4,6 Kg of FeMn with 36,44 %Mn, [4] 4,3 Kg of FeMn with 31,13 %Mn, and [5] 12,8 Kg of FeMn with 75,19 %Mn. The effect of Mn-blend in this ferromanganese production was by the increasing composition of the medium grade manganese ore (MG) that will cause: (a) the increasing number of cokes and the decreasing of limestone required, (b) the increasing of yield, the number of products, and also the percentage of manganese content FeMn, and (c) the decreasing of energy consumption required., The potential reserve of manganese ore in Indonesia is very large, but it was located in different locations spread throughout Indonesia. Manganese ore is one of raw material in producing ferromanganese that is not replaceable in the world steel industry. Ferromanganese (FeMn) is an alloying metal that contained of 75% Manganese (Mn) and 25% Iron (Fe) which is generally used in the process of iron/steel making to improve its mechanical properties. In this experiment, ferromanganese production was conducted by blending two kinds of manganese ore, that was low grade Mn ore (LG) which derived from Tanggamus, Lampung (16,3 %Mn-19,2 %Fe-20,2 %Si) and medium grade Mn ore (MG) which derived from Jember, East Java (27,7 %Mn-4,4 %Fe-14,7 %Si), to obtain ferromanganese with a minimum content of 50 %Mn. The composition of Mn-blend in this experiment was [1] 25 %LG+75 %MG, [2] 50 %LG+50 %MG, [3] 75 %LG+25 %MG, [4] 100 %LG, and [5] 100 %MG. This mixed manganese ore was processed by using Submerged Arc Furnace (SAF). Cokes and limestone was added into the furnace as reductant and flux agent, respectively. Those raw materials are smelted until 1500 °C. To determine the composition of raw materials and the product of FeMn, analysis such as XRF (X-Ray Fluorescence), XRD (XRay Diffraction), AAS (Atomic Absorption Spectrometry), and proximate have to be done. From each composition of Mn-blend above in this experiment, it was obtained that [1] 5,2 Kg of FeMn with 54,05 %Mn, [2] 4,75 Kg of FeMn with 50,03 %Mn, [3] 4,6 Kg of FeMn with 36,44 %Mn, [4] 4,3 Kg of FeMn with 31,13 %Mn, and [5] 12,8 Kg of FeMn with 75,19 %Mn. The effect of Mn-blend in this ferromanganese production was by the increasing composition of the medium grade manganese ore (MG) that will cause: (a) the increasing number of cokes and the decreasing of limestone required, (b) the increasing of yield, the number of products, and also the percentage of manganese content FeMn, and (c) the decreasing of energy consumption required.]

Abstrak :
[ABSTRAK
Logam ferromangan adalah salah satu unsur paduan penting pada baja untuk meningkatkan sifat mekanis, ketahanan aus, dan kekerasannya. Bentuk ferromangan (FeMn) telah diatur dalam standard ASTM dengan kadar minimal sebesar 75% Mangan (Mn). Tujuan penelitian ini adalah pembuatan logam FeMn dengan kandungan minimal 60%Mn dari bijih mangan lokal dan mempelajari efek dari basasitas terak yang dipengaruhi oleh penambahan kapur sebagai zat aditif dalam proses pembuatan ferromangan terhadap jumlah produk ferromangan yang dihasilkan dan konsumsi energi yang dibutuhkan dalam proses tersebut. Dalam penelitian ini digunakan bijih mangan lokal kadar menengah dari daerah 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), 7.5 kg kokas, dan jumlah batu kapur yang bervariasi, yaitu; 8, 10, 12, dan 14 kg. Proses peleburan berlangsung pada temperatur 1200-1500 oC. Kemudian hasil akan dianalisa dengan menggunakan XRF (X-Ray Fluoroscence), XRD (X-Ray Diffraction), 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 8.2 kg FeMn, kemudian memaksimalkan kadar % mangan yang tereduksi pada logam hingga mencapai komposisi kimia yang optimal (78,13 Mn-12,65 Fe-8.93 Si), menekan konsumsi energi hingga 9.8 kwh/kg ferromangan, menekan angka konsumsi elektroda, dan menghasilkan prosentase efisiensi proses berupa % yield yang cukup tinggi yakni sebesar 58.61%. Hasil lain yang menunjang proses pengolahan ferromangan dengan meningkatnya hasil basasitas terak adalah tercapainya suhu reaksi yang tinggi yakni sebesar 15940C sehingga membuat reduksi oksida mangan pada terak menjadi mangan pada logam semakin baik, kemudian jumlah terak juga dapat ditekan. Selanjutnya secara tinjauan aspek ekonomi dari keempat kali proses penelitian, maka didapatkan hasil yang paling menguntungkan sebesar Rp 5.731,-/proses. ABSTRACT
Ferromanganese metal is an important alloying element in steel production industry used to maximize its mechanical properties such as wear resistance and hardness. The most common form of ferromanganese according to ASTM standard contain min.75%Mn and max.25%Fe inside the product. The target of this research is to obtain ferromanganese metal with min.60%Mn using medium grade manganese 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 kind of basicity will determined by the amount of limestone as fluxing agent which added to the furnace. Moreover, this study will focus to the effect of its slag basicity on the number of ferromanganese product and the amoung of energy consumption. This study was taking place at UPT BPM LIPI Lampung, Sumatera. Using their Mini Sub-merged Arc Furnace (SAF) the process began without any beneficiation processs for its raw material. Manganese ore Ø ±30mm, cokes, and limestones 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, 7.5 kg cokes, and limestones which varied from 8, 10, 12, and 14 kg. Validity of this study supported by the chemical analysis which took place before and after reduction process using some tools such as XRF (X-Ray Fluoroscence), XRD (XRay Diffraction), AAS (Atomic Absorbtion Spectrometry), and Proxymate analysis. The result of this research showed an increasing trend in product?s quality as the slag basicity and the amount of limestone increased. As the slag basicity increase, the number of ferromanganese metal products were also increased until 8.2 kg FeMn and the amount of manganese element in metal phase also showed the most optimum chemical composition of ferromanganese metal (78,13 Mn- 12,65 Fe-8.93 Si). Furthermore, the energy consumption can be reduced until 9.8 kwh/kg FeMn as well as the electrodes consumption and also the efficiency percentage or % yield process can be increased up to 58.61%. Other parameters which used to support these 4-times-research plan was the temperature level which turned out to be as high as 15940C and helped the reduction process of manganese oxide into manganese metal became easier. Not only to obtain more manganese content in metal phase, but also this level of reduction temperature can reduced the amount of slag. Finally, in addition to support the optimum data, economic analysis also 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 production industry used to maximize its mechanical properties such as wear resistance and hardness. The most common form of ferromanganese according to ASTM standard contain min.75%Mn and max.25%Fe inside the product. The target of this research is to obtain ferromanganese metal with min.60%Mn using medium grade manganese 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 kind of basicity will determined by the amount of limestone as fluxing agent which added to the furnace. Moreover, this study will focus to the effect of its slag basicity on the number of ferromanganese product and the amoung of energy consumption. This study was taking place at UPT BPM LIPI Lampung, Sumatera. Using their Mini Sub-merged Arc Furnace (SAF) the process began without any beneficiation processs for its raw material. Manganese ore Ø ±30mm, cokes, and limestones 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, 7.5 kg cokes, and limestones which varied from 8, 10, 12, and 14 kg. Validity of this study supported by the chemical analysis which took place before and after reduction process using some tools such as XRF (X-Ray Fluoroscence), XRD (XRay Diffraction), AAS (Atomic Absorbtion Spectrometry), and Proxymate analysis. The result of this research showed an increasing trend in product’s quality as the slag basicity and the amount of limestone increased. As the slag basicity increase, the number of ferromanganese metal products were also increased until 8.2 kg FeMn and the amount of manganese element in metal phase also showed the most optimum chemical composition of ferromanganese metal (78,13 Mn- 12,65 Fe-8.93 Si). Furthermore, the energy consumption can be reduced until 9.8 kwh/kg FeMn as well as the electrodes consumption and also the efficiency percentage or % yield process can be increased up to 58.61%. Other parameters which used to support these 4-times-research plan was the temperature level which turned out to be as high as 15940C and helped the reduction process of manganese oxide into manganese metal became easier. Not only to obtain more manganese content in metal phase, but also this level of reduction temperature can reduced the amount of slag. Finally, in addition to support the optimum data, economic analysis also showed that this composition was the most profitable process with Rp 5.731,- /process as its profit.]

Abstrak :
[ABSTRAK
Mangan 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. ABSTRACT
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., 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.]