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<p>Refractory gold ore (RGO) is characterized by poor gold recovery during direct leaching due to the encapsulation of gold particles within sulfide matrices. In this study, a synergistic microwave-assisted roasting and leaching (MAR–MAL) method was developed to improve gold extraction using an environmentally friendly iodine–ethaline deep eutectic solvent (DES) system as an alternative to cyanide-based leaching. The roasting step decomposed sulfide minerals, thereby increasing gold exposure, while the subsequent microwave-assisted leaching process facilitated rapid and efficient dissolution of gold. Microwave irradiation was applied in both steps to reduce processing time and energy consumption. Process variables including microwave power, iodine concentration, and leaching duration were optimized using response surface methodology (RSM). The optimum leaching conditions were achieved at 200 W microwave power, 0.035&#xa0;M iodine concentration, 160&#xa0;°C temperature, 25% (m/v) solid-to-liquid ratio, 300&#xa0;rpm stirring, and 9.5&#xa0;min of contact time. Under these conditions, gold extraction increased from 47.5% (direct leaching of untreated RGO) to 75.3% using MAL. With pretreatment via MAR, conventional leaching reached 73.0%, while the combined MAR–MAL process achieved 93.4% gold extraction, demonstrating clear synergy between the two steps. Kinetic analysis indicated surface chemical reaction control, and thermodynamic evaluation confirmed favorable complexation of gold with iodide in DES. This study highlights the potential of the MAR–MAL strategy using iodine and ethaline as a green, recyclable alternative to cyanide for gold recovery from refractory ores. The integrated process offers significant advantages in terms of efficiency, sustainability, and environmental safety, paving the way for cleaner hydrometallurgical practices.</p> Graphical Abstract <p></p>

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Synergistic Microwave-Assisted Roasting and Leaching to Enhance Gold Extraction from Refractory Gold Ore Using an Environmentally Friendly Deep Eutectic Solvent

  • 期刊论文

  • 发表日期：

    2026年1月26日

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  • Abdul Hapid,
  • Adji Kawigraha,
  • Nur Vita Permatasari,
  • Nur Ikhwani,
  • Siti Zullaikah,
  • Mahfud Mahfud,
  • Suttichai Assabumrungrat

摘要

Refractory gold ore (RGO) is characterized by poor gold recovery during direct leaching due to the encapsulation of gold particles within sulfide matrices. In this study, a synergistic microwave-assisted roasting and leaching (MAR–MAL) method was developed to improve gold extraction using an environmentally friendly iodine–ethaline deep eutectic solvent (DES) system as an alternative to cyanide-based leaching. The roasting step decomposed sulfide minerals, thereby increasing gold exposure, while the subsequent microwave-assisted leaching process facilitated rapid and efficient dissolution of gold. Microwave irradiation was applied in both steps to reduce processing time and energy consumption. Process variables including microwave power, iodine concentration, and leaching duration were optimized using response surface methodology (RSM). The optimum leaching conditions were achieved at 200 W microwave power, 0.035 M iodine concentration, 160 °C temperature, 25% (m/v) solid-to-liquid ratio, 300 rpm stirring, and 9.5 min of contact time. Under these conditions, gold extraction increased from 47.5% (direct leaching of untreated RGO) to 75.3% using MAL. With pretreatment via MAR, conventional leaching reached 73.0%, while the combined MAR–MAL process achieved 93.4% gold extraction, demonstrating clear synergy between the two steps. Kinetic analysis indicated surface chemical reaction control, and thermodynamic evaluation confirmed favorable complexation of gold with iodide in DES. This study highlights the potential of the MAR–MAL strategy using iodine and ethaline as a green, recyclable alternative to cyanide for gold recovery from refractory ores. The integrated process offers significant advantages in terms of efficiency, sustainability, and environmental safety, paving the way for cleaner hydrometallurgical practices.

Graphical Abstract