One-Step Silver Leaching from Manganese-Silver Ore Enabled by Hydrogen-Bonded Network Formation

Area of Science:

• Green Chemistry
• Materials Science
• Metallurgy

Background:

• Silver scarcity necessitates sustainable extraction methods for low-grade ores.
• Conventional cyanidation poses significant toxicity and environmental risks, limiting its sustainability.
• Developing eco-friendly leaching systems is crucial for modern silver metallurgy.

Purpose of the Study:

• To develop a novel, non-toxic, and efficient silver leaching system for polymetallic manganese-silver ores.
• To investigate the mechanism of silver leaching using a synergistic system of oxalic acid and cyano-functionalized quaternary ammonium salts.
• To demonstrate a sustainable alternative to traditional cyanidation methods.

Main Methods:

• A one-step leaching process utilizing oxalic acid and cyano-functionalized branched quaternary ammonium salts.
• Kinetic studies to analyze the two-stage leaching process.
• Spectroscopic characterization and theoretical calculations to elucidate the silver chloride complexation and helical structure formation.

Main Results:

• Achieved over 90% silver recovery from polymetallic manganese-silver ore under mild conditions.
• Identified a two-stage leaching mechanism involving manganese oxide dissolution and iron matrix breakdown.
• Discovered a unique inorganic helical chain structure formed by AgCl and chloride anions, stabilized by hydrogen bonds, which facilitates silver dissolution.

Conclusions:

• The developed leaching system offers an efficient, selective, and sustainable method for silver extraction.
• The cooperative effect of hydrogen bonds in stabilizing helical structures provides a new mechanism for overcoming high lattice energies in solids.
• This research presents a novel H-bond-directed design strategy for sustainable metallurgical processes.