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"Penelitian ini dilakukan untuk menyelidiki pengaruh sulfur yang terkandung dalam batubara antrasityang digunakansebagai reduktoruntuk proses reduksi selektifmenggunakan bijih nikel laterit. Proses reduksi dilakukan dalam berbagai variasi temperatur(950 °C, 1050 °C, dan 1150 °C).Bijih nikel laterit yang digunakan dalam penelitian ini adalah bijih nikel sarpolitik dengan kadar Ni 1,74% dan kadar Fe 30%. Jenis reduktor yang digunakan adalah batubara antrasit 2,68%S dan batubara antrasit 5%S. Penggunaan reduktor divariasikan dengan jumlah stoikiometri dari 0,0625-0,25. Penelitian ini juga menggunakan natrium sulfat (Na2SO4) sebagaiaditifdengan komposisi campuran 10% berat dari bahan baku utama. Hasil reduksi kemudian dipisahkan antara konsentrat dengan tailing menggunakan metode separasi magnetik. Hasil pengujian menunjukkanbahwa peningkatan temperatur reduksi dapat menyebabkan peningkatan kadar dan recovery nikel. Hasil pengujian juga menunjukkanbahwa penggunaan reduktor antrasit 2,68% S pada stoikiometri 0,25 menghasilkan kadar dan recoverynikel yang paling optimal.

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This study is conducted to investigate the effect of sulfur contained in the anthracite coal that was used as a reductant for the selective reduction process using saprolitic nickel ore. The reduction process is carried out in various temperature variations of 950ºC, 1050ºC, and 1150ºC.The saprolitic nickel ore was used in this experiment containing 1,74% Ni and 30% Fe. The anthracite coal with different sulfur content, i.e., 2.68%S and 5%S, was used as a reductant in this experiment. The addition of reductants is varied with a stoichiometric amount of 0.0625-0.25. This research also used 10 wt.% of sodium sulfate (Na2SO4) as an additive. Samples that have been reduced were then separated into the concentrate and the tailings using the magnetic separation method. The study resulted that an increase in temperature reduction has increased in nickel content and recovery. The study also suggested that the use of 2.68% S anthracite coal as a reductant at 0.25 stoichiometry produced the most optimal nickel content and recovery."

"Sources nickel laterite deposit of the world are mostly found in the tropic such as Indonesia. The initial composition of nickel saprolite ore is characterized by XRF. Saprolte ore was reduced use coal 15% wt at 1000°C for 60 minutes. The result of reduction is characterized by XRD. Effect of roasting reduction to recovery nickel also affect the result leaching use solvent sulphuric acid (H2SO4) for 240 minutes at 100°C with varying concentrations of 0.5 M, 1 M, and 2 M. The content of nickel dissolved in pregnant leach solution calculated using Atomic Absorbance Spectroscopy (AAS).

Result of XRD characterization shows phase transformation into Fe3O4, NiO, and FeNi after reduction roasting. Sulphuric Acid at concentration 1 Molar has the highest nickel recovery with 52.75% in reduced saprolite ore."

"Nikel merupakan logam penting yang banyak digunakan dalam paduan, misalnya baja tahan karat, paduan ruang angkasa, dan paduan khusus. Nikel ditambang dari dua jenis bijih: laterit dan sulfida. Laterit banyak ditemukan di daerah tropis seperti di Indonesia dan ditambang untuk memperoleh nikel dan kobalt. Pelindian bijih nikel laterit pada tekanan atmosfer saat ini banyak menarik perhatian karena biaya yang lebih rendah dibanding proses lainnya. Tujuan penelitian ini adalah untuk menentukan pengaruh waktu dan kecepatan agitasi pelindian atmosferik terhadap persentase perolehan nikel dari bijih laterit jenis saprolit. Bijih nikel saprolit dari Halmahera Timur digunakan dalam penelitian. Untuk mengetahui nilai perolehan nikel pada waktu dan kecepatan agitasi yang berbeda, pelindian teragitasi dilakukan selama 1, 3, dan 5 jam dengan kecepatan agitasi masing-masing 250 rpm, 500 rpm, dan 750 rpm. Selama penelitian, berat sampel yang telah dihaluskan (15 g), konsentrasi asam sulfat (5N (240.1 g/L)), volume asam sulfat (75 ml), dan suhu (100°C) dijaga konstan. Dapat dilihat bahwa dalam pelindian teragitasi, peningkatan waktu pelindian dari 1 jam hingga 5 hour memiliki pengaruh positif terhadap perolehan nikel. Peningkatan kecepatan agitasi dari 250 rpm hingga ke 750 rpm juga meningkatkan nilai perolehan nikel.

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Nickel is important metal that is mostly used in alloys, for example, in stainless steels, aerospace alloys and specialty steels. Nickel is mined from two types of ores: laterites and sulfides. Laterites are found mostly in tropical regions and are mined for their nickel and cobalt in countries like Indonesia. Leaching lateritic nickel ores with sulphuric acid at atmospheric pressure (AL) has been recently receiving more attention due to lower cost compared to other processes. The purpose of this study is to determine the effect of duration and agitation speed of atmospheric leaching to the recovery percentage of nickel from saprolitic type laterit ore. Saprolitic nickel ores from Eastern Halmahera were used during experiments. In order to study the recovery values at different time periods and different agitation speeds, agitative leaching experiments were carried out for 1, 3, and 5 hours with agitation speed 250 rpm, 500 rpm, and 750 rpm, respectively. During the experiments, weight of ground ore sample (15 g), concentrations of sulfuric acid (5N (240.1 g/L)), volume of sulfuric acid (75 ml), and temperature (100°C) were kept constant. It was shown that in agitative leaching, increasing leaching time from 1 hour to 5 hour had a positive effect on metal extractions. Increasing agitation speed from 250 rpm to 750 rpm also increased the recovery values of nickel."

"Deposit laterite merupakan salah satu jenis bijih nikel yang paling berlimpah di alam. Di Indonesia khususnya di Kabupaten Pomala, Sulawesi Tenggara memiliki deposit laterite yang tergolong tinggi. Salah satu mineral yang ada di dalam lapisan laterite yaitu bijih nikel saprolit yang memiliki kadar unsur nikel yang lebih tinggi dibandingkan lapisan lainnya seperti limonit. Untuk mendapatkan recovery nikel yang efektif dan efisien, diperlukan suatu pengembangan penelitian proses ekstraksi. Pada penelitian ini akan dilakukan beberapa proses seperti separasi dengan fluida air, pirometalurgi (roasting reduction) dan hidrometalurgi (pelindian). Penelitian ini akan membahas pengaruh penambahan reduktor yang berasal dari batubara dengan kadar yang berbeda-beda yaitu 8%, 16%, 24% dan 32%. Untuk mengetahui komposisi kimia dari bijih saprolit yang murni dan yang telah dilakukan proses separasi, akan dilakukan pengujian EDX (Energy Dispersive X-Ray) terlebih dahulu. Sebelum ketahap hidrometalurgi, sampel dengan masing-masing penambahan batubara tersebut dilakukan proses roasting reduction pada temperatur 1250oC di dalam furnace carbolyte. Selanjutnya akan dilakukan pengujian STA dan XRD dengan tujuan untuk melihat senyawa-senyawa yang terdapat pada bijih nikel saprolit tersebut. Setelah tahap ini selesai dilakukan, sampel dilindi dengan menggunakan larutan Asam Sulfat 1 Molar dalam waktu 90 menit. Dari hasil yang diperoleh, pada proses pelindian asam sulfat dengan konsentrasi 1 Molar, persentase recovery nikel yang tertinggi berada pada bijih saprolit yang ditambahkan dengan batubara sebanyak 16% dengan perolehan Nikel nya yaitu sebesar 59.85% (persentase optimum).

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Laterite deposit is one of the most abundant ore in nature. In Indonesia, especially in Pomala regency, Southeast Sulawesi, has a high laterite deposit. One of the minerals in the laterite layer is saprolite nickel ore which has a higher nickel content than the other layers, such as limonite.

To get recovery of nickel with effective and efficient, a study about development of extraction process is needed. This research will conduct several processes such as float and sink process, pyrometallurgy (roasting reduction) and hydrometallurgical (leaching). This research also will disscus the effect of addition of coal as reductor, with varied levels of coal: 8%, 16%, 24% and 32%. To determine the chemical composition of saprolite ore that have been treated by float and sink process, EDX (Energy dispersive X-Ray) test is performed.

Before hydrometallurgy process is conducted, the samples that have been added by varied levels of coal was reduction roasted at temperature 1250oC in Carbolyte furnace. Further testing will be conducted by the STA and XRD with purpose to determine the compounds presence in the saprolite nickel ore. After that stage, the sample is leached in Sulfuric Acid at 1 Molar for 90 minutes.

From the obtained results, the process of leaching with sulfuric acid at 1 Molar, the recovery percentage of nickel from 16% of coal addition is the highest with obtained value 59.85% (optimum percentage)."