Hapid, Abdul (2024) Aplikasi Gelombang Mikro untuk Meningkatkan Recovery pada Proses Leaching (Pelindian) Bijih Emas dengan Deep Eutectic Solvent (DES). Doctoral thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Bijih emas secara metalurgi terdiri dari bijih emas free milling dan bijih emas refraktori. Bijih free milling lebih mudah diolah dengan recovery emas yang tinggi dibandingkan dengan bijih refraktori. Cadangan bijih emas free milling di dunia semakin berkurang, sehingga sektor industri mulai memanfaatkan bijih emas refraktori. Butiran emas dalam bijih emas refraktori umumnya berukuran halus dan terenkapsulasi dalam mineral sulfida sehingga memerlukan pretreatment sebelum pelindian. Selain itu, industri ekstraksi emas juga masih berbasis pada proses sianidasi yang tidak ramah lingkungan. Pada penelitian ini, roasting dan pelindian berbantuan gelombang mikro telah digunakan sebagai metode pretreatment dan ekstraksi emas dari bijih emas refraktori yang berasal dari Arinem dan Cikondang – Jawa Barat. Deep eutektic solvent (DES) yang ramah lingkungan digunakan sebagai pelarut menggantikan sianida pada pelindian. Proses berbantuan gelombang mikro memiliki keunggulan yaitu waktu proses sangat singkat dan konsumsi energi sangat rendah. Bijih emas asal Arinem memiliki kadar Au 2.13 ppm dan kadar sulfur 1.40%, sedangkan bijih emas asal Cikondang memiliki kadar Au 8.10 ppm dan kadar sulfur 8.60%. Kondisi optimum roasting berbantuan gelombang mikro terhadap bijih emas Arinem dicapai pada daya gelombang mikro 400 watt, NaClO3 180 kg/ton bijih dan air 180 kg/ton bijih selama 30 menit dengan oksidasi mineral sulfida 90.6%. Sedangkan kondisi optimum roasting bijih asal Cikondang tercapai pada daya 200 watt, NaClO3 200 kg/ton bijih dan air 150 kg/ton bijih selama 5 menit dengan oksidasi mineral sulfida 67.3%. Kondisi optimum pelindian berbantuan gelombang mikro terhadap bijih emas Cikondang setelah roasting mencapai ekstraksi Au 93.42% pada 200 watt, DES (kolin klorida – etilen glikol 1:2), 0.035M I2, 300 rpm, perbandingan padat/cair 25% selama 9.5 menit dengan temperatur pelindian 160°C. Kinetika pelindian bijih emas refraktori hasil roasting dikontrol oleh reaksi kimia dengan energi aktivasi 47.98 kJ/mol. Pemisahan ion logam pengotor Fe, Cu, Pb dan Zn yang terdapat dalam larutan hasil pelindian diperlukan sebelum elektrowining Au. Presipitasi pada pH 3.5 dan temperatur 30°C selama 60 menit berhasil mengendapkan 99.99% Fe, 97.68% Cu, 94.49% Pb dan 94.08% Zn dari larutan hasil pelindian. Elektrowining Au dari larutan hasil pelindian dapat dilakukan secara simultan dengan recovery iodin dan daur ulang DES. Aplikasi gelombang mikro pada roasting dan pelindian bijih emas refraktori dapat meningkatkan recovery emas dengan sangat signifikan dengan waktu yang sangat singkat dan energi yang sangat rendah. Larutan tipe DES dengan oksidator iodin yang ramah lingkungan dapat menggantikan sianida pada pelindian bijih emas.
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Gold ore metallurgically consists of free-milling and refractory gold ore. Free milling gold ore can be processed easily with higher gold recovery than refractory ore. The world's reserves of free-milling gold ore are decreasing, and the gold mining industry has started processing refractory gold ore. Gold particles in refractory ore are generally fine and encapsulated in sulfide minerals, requiring pretreatment before leaching. In addition, the gold extraction industry is still based on the cyanidation process, which is not environmentally friendly. Microwave-assisted roasting and leaching have been used as pretreatment and gold extraction methods for processing refractory gold ore from Arinem and Cikondang - West Java, Indonesia.. Environmentally friendly deep eutectic solvent (DES) was used as a cyanide substitute solvent in leaching. The microwave-assisted process has the advantages of very short processing time and very low energy consumption. Gold ore from Arinem has an Au content of 2.13 ppm and a sulfur content of 1.40%, while gold ore from Cikondang has an Au content of 8.10 ppm and a sulfur content of 8.60%. The optimum microwave-assisted roasting conditions for Arinem gold ore were achieved at 400 watts, NaClO3 180 kg/tonne of ore, and water 120 kg/tonne of ore for 30 minutes with sulfide mineral oxidation of 90.6%. The optimum roasting conditions for Cikondang ore were achieved at 200 watts, NaClO3 200 kg/tonne of ore, and water 150 kg/tonne of ore for 5 minutes with sulfide mineral oxidation of 67.3%. The optimum condition of microwave-assisted leaching of Cikondang gold ore after roasting achieved 93.42% Au extraction at 200 watts, DES (Choline Chloride – Ethylene Glycol 1:2), 0.035M I2, 300 rpm, solid/liquid ratio 25% for 9.5 minutes with a leaching temperature of 160°C. The leaching kinetics of the roasted refractory gold ore was controlled by a chemical reaction with an activation energy of 47.98 kJ/mol. Separation of impurity metal ions Fe, Cu, Pb, and Zn contained in the pregnant leach solution was required before Au electrowinning. Precipitation at pH 3.5 and a temperature of 30°C for 60 minutes successfully precipitated 99.99% Fe, 97.68% Cu, 94.49% Pb, and 94.08% Zn from the pregnant leach solution. Electrowinning of Au from leach solution can be be carried out simultaneously with iodine and DES recycling. Microwave-assisted roasting, followed by microwave-assisted leaching, has successfully increased recovery in refractory gold ore processing. DES (choline chloride-ethylene glycol 1:2) and iodine can substitute cyanide in gold ore leaching.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Uncontrolled Keywords: | bijih emas refraktori, ekstraksi, pretreatment, pelindian berbantuan gelombang mikro, recovery, roasting berbantuan gelombang mikro, elektrowining, refractory gold ore, deep eutectic solvent, extraction, pretreatment, microwave-assisted leaching, microwave-assisted roasting |
| Subjects: | Q Science > QD Chemistry > QD63 Extraction |
| Divisions: | Faculty of Industrial Technology and Systems Engineering (INDSYS) > Chemical Engineering > 24001-(S3) PhD Thesis |
| Depositing User: | Abdul Hapid |
| Date Deposited: | 02 Sep 2024 02:05 |
| Last Modified: | 02 Sep 2024 02:05 |
| URI: | http://repository.its.ac.id/id/eprint/115581 |
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