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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.]