Determination of Ferric and Cupric Ions in Copper Refining Solutions

Significance of the topic

Monitoring ferric (Fe3+) and cupric (Cu2+) ions in copper refining solutions is essential to ensure product purity, optimize process efficiency, minimize reagent consumption and control environmental emissions. Precise quantification of these metal ions supports decision making in metallurgical operations and quality assurance in industrial analytics.

Objectives and study overview

This study describes a thermometric titration approach for sequential determination of Fe3+ and Cu2+ in copper refinery liquors. It aims to address limitations in conventional iodometric assays that rely on masking iron, which may fail under certain process conditions. By first measuring Fe3+ via fluoride titration and then determining the combined Fe3+ and Cu2+ by iodometric titration, the method calculates Cu2+ by difference.

Methodology and instrumentation

The analytical procedure comprises two titrations performed on a thermometric titrator equipped with an 802 stirrer and temperature sensor. Reagents include:

• 1 mol/L NaF standard solution and combined acetate buffer for Fe3+ titration
• 1 mol/L Na2S2O3 standard solution, glacial acetic acid, 50% KI solution and 0.04 mol/L KIO3 solution for Fe3+ + Cu2+ titration

Sample aliquots are acidified and titrated under controlled delivery rate, stirring speed, and data smoothing for detection of exothermic endpoints. Fluoride titration quantifies Fe3+, followed by iodometric titration to measure total Fe3+ + Cu2+. Standardization protocols for both titrants are described to ensure accuracy.

Key results and discussion

Analysis of refinery solutions containing Fe2+, Fe3+ and Cu2+ demonstrated high precision and reproducibility. Five samples showed Cu2+ concentrations ranging from approximately 3.3 to 61.7 g/L and Fe3+ from 2.37 to 11.55 g/L with negligible variation between replicates. Data confirm effective oxidation of ferrous iron, stability of the Fe(H2O)6^3+ complex in acidic media, and clear thermometric endpoints for both titrations. Subtraction of Fe3+ values from the combined assay yielded accurate Cu2+ results without interference from other matrix components.

Benefits and practical applications

• Rapid, automated determination reduces analysis time and operator intervention
• Eliminates the need for separate iron masking steps
• Offers robust performance in complex refinery media
• Supports routine QA/QC and process monitoring in copper production

Future trends and opportunities

Expanding thermometric titration to inline and flow-injection platforms could enable real-time monitoring of metallurgical processes. Integration with digital control systems and machine learning for endpoint detection may further enhance analytical throughput and data reliability. Development of multi-element protocols could broaden the application of thermometric titration in industrial analytics.

Conclusion

The thermometric titration method presented provides a reliable, precise and streamlined approach for sequential determination of Fe3+ and Cu2+ in copper refining solutions. By combining fluoride and iodometric titrations, it overcomes masking challenges and supports high-throughput quality control in industrial settings.

Reference

Thermo Titration Application Note No. H-070: Determination of Ferric and Cupric Ions in Copper Refining Solutions