Presipitasi Selektif Nikel dan Kobalt Menggunakan Mg(OH)2 dari Bittern Garam Laut pada Pengolahan Hidrometalurgi Bijih Nikel Laterit

Subandrio, Subandrio (2026) Presipitasi Selektif Nikel dan Kobalt Menggunakan Mg(OH)2 dari Bittern Garam Laut pada Pengolahan Hidrometalurgi Bijih Nikel Laterit. Doctoral thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Penelitian ini bertujuan untuk mengekstraksi logam nikel dari bijih nikel limonit asal Desa Lameruru, Kabupaten Konawe Utara, Sulawesi Tenggara, dengan memanfaatkan Mg(OH)2 yang disintesis dari bittern (limbah kristalisasi garam) asal Osowilangon, Surabaya, sebagai agen pengendap. Penelitian dilakukan dalam empat tahap, yaitu: (1) pelindian (leaching) bijih nikel menggunakan asam sulfat dengan variasi konsentrasi (1, 3, 5, 7,8 M), temperatur (30-70 °C), dan waktu (1–6 jam); (2) sintesis Mg(OH)2 dari bittern dengan variasi pengendapan pada pH 10, 11, dan 12; (3) presipitasi nikel dari Pregnant Leach Solution (PLS) menggunakan Mg(OH)2 menjadi Mixed Hydroxide Precipitate (MHP) pada variasi pH 6, 7, dan 8; serta (4) electrowinning larutan re-leach MHP pada variasi tegangan 0,25; 0,5; 1; dan 4 V. Karakterisasi bahan dan produk dilakukan dengan XRD, XRF, dan AAS. Hasil analisis XRD dan XRF menunjukkan bahwa bijih yang digunakan berada pada zona limonit dengan mineral pembawa nikel berupa geotit (Fe2O3·H2O), kandungan Fe2O3 >50%, dan Ni sebesar 1,49%. Optimasi pelindian bijih nikel menunjukkan bahwa konsentrasi H2SO4 optimum adalah 5 M yang menghasilkan 80,79% nikel terekastrasi, suhu optimum 70 °C (60,87% nikel terekstraksi), dan waktu optimum 5 jam (60,7% nikel terekstraksi). Sintesis Mg(OH)2 dari bittern menunjukkan bahwa pengendapan pH 11 merupakan pH terbaik pengendapan dengan kadar Mg sebesar 38,517%. Presipitasi MHP terbaik untuk nikel dengan kadar tertinggi sebesar 38,472% dilakukan pada pH 7, sedang kobalt kadar tertinggi sebesar 3,82% dilakukan pada pH 8. Proses electrowinning pada larutan hasil pelarutan kembali MHP dengan asam sulfat encer (0,5 M) menunjukkan bahwa tegangan optimum adalah 1 V, yang menghasilkan padatan dengan kadar nikel pada katoda mencapai 89,68%. Hasil ini memberikan informasi dasar terkait potensi penggunaan Mg(OH)2 dari bittern sebagai agen pengendap untuk proses ekstraksi nikel dari bijih limonit.
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This study aimed to extract nickel from limonite nickel ore originating from Lameruru Village, North Konawe Regency, Southeast Sulawesi, Indonesia, using Mg(OH)2 synthesized from bittern, a by-product of salt crystallization from Osowilangon, Surabaya, as a precipitating agent. The study consisted of four stages: (1) leaching of the nickel ore using sulfuric acid at varying concentrations (1, 3, 5,7 and 8 M), temperatures (30–70 °C), and leaching times (1–6 h); (2) synthesis of Mg(OH)2 from bittern by precipitation at pH 10, 11, and 12; (3) precipitation of nickel from the pregnant leach solution (PLS) using Mg(OH)2 to produce mixed hydroxide precipitate (MHP) at pH 6, 7, and 8; and (4) electrowinning of the MHP re-leach solution at applied voltages of 0.25, 0.5, 1, and 4 V. The raw materials and products were characterized using XRD, XRF, and AAS. XRD and XRF analyses indicated that the ore was classified within the limonite zone, with goethite (Fe2O3·H2O) as the principal nickel-bearing mineral, an Fe2O3 content of >50%, and a Ni content of 1.49%. Optimization of the ore leaching process showed that the optimum H2SO4 concentration was 5 M, resulting in 80.79% nickel extraction, while the optimum temperature and leaching time were 70 °C and 5 h, yielding nickel extraction efficiencies of 60.87% and 60.7%, respectively. The synthesis of Mg(OH)2 from bittern showed that pH 11 was the optimum precipitation condition, producing a Mg content of 38.517%. The highest nickel grade in the mixed hydroxide precipitate (MHP) was 38.472%, obtained at pH 7, whereas the highest cobalt grade was 3.82%, obtained at pH 8. Electrowinning of the MHP re-leach solution using dilute sulfuric acid (0.5 M) showed that an applied voltage of 1 V was optimal, producing a cathodic deposit with a nickel content of 89.68%. These results provide fundamental information on the potential application of bittern derived Mg(OH)2 as a precipitating agent for nickel extraction from limonite ore.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	bijih nikel limonit, bittern, Mg(OH)2, Mixed Hydroxide Precipitate (MHP), electrowinning ; limonite nickel ore, bittern, Mg(OH)₂, Mixed Hydroxide Precipitate (MHP), electrowinning
Subjects:	T Technology > TN Mining engineering. Metallurgy T Technology > TN Mining engineering. Metallurgy > TN799.N6 Nickel--Metallurgy
Divisions:	Faculty of Science and Data Analytics (SCIENTICS) > Chemistry > 47001-(S3) PhD Thesis
Depositing User:	Subandrio Subandrio
Date Deposited:	12 Nov 2026 07:26
Last Modified:	12 Nov 2026 07:26
URI:	http://repository.its.ac.id/id/eprint/146059

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