Kinetics and Modeling of Counter-Current Leaching of Waste Random-Access Memory Chips in a Cu-NH₃-SO₄ System...

Area of Science:

• Metallurgical Engineering
• Environmental Science
• Chemical Engineering

Background:

• Ammoniacal leaching is an established method for copper (Cu) recovery from waste printed circuit boards (WPCBs).
• Integrating leaching with electrowinning (EW) offers a potential pathway for efficient copper recycling.

Purpose of the Study:

• To develop and model a counter-current leaching circuit for enhanced copper recovery from WPCBs.
• To investigate the kinetic parameters influencing copper leaching in ammoniacal solutions.
• To couple the leaching circuit with an electrowinning cell for a comprehensive recycling process.

Main Methods:

• Experimental determination of copper leaching kinetics from waste RAM chips using ammoniacal solutions.
• Kinetic data analysis using the Zhuravlev changing-concentration model.
• Adaptation of kinetic data to the Jander constant concentration model for a continuously stirred tank reactor (CSTR) leaching function.
• Development and simulation of a 4-stage counter-current leaching circuit model.

Main Results:

• Particle size and initial Cu(II) concentration were critical factors for copper leaching efficiency.
• Maximum copper recovery of 96% was achieved with a 1.2 mm particle size and 40 g/L initial Cu(II) concentration.
• The modeled 4-stage counter-current circuit achieved 93% copper recovery with a 4.12 g/L Cu(II) output.

Conclusions:

• The developed kinetic framework and counter-current circuit model provide a viable tool for optimizing copper recovery from WPCBs.
• The study demonstrates the feasibility of coupling ammoniacal leaching with electrowinning for efficient copper recycling from electronic waste.