Case Study
Use of Functionalised Scavengers
for Precious Metal Recovery
Abstract
Scavengers are functionalised materials, typically in the form of polymers or silicas, that selectively bind precious metals (PMs) from a solution.
They are highly effective in the recovery of platinum group metals (PGMs) such as platinum (Pt) and palladium (Pd). These materials can be used in fixed-bed columns or stirred tanks, with the flexibility to install them onsite or offsite.
Effective precious metal recovery involves careful consideration of the following aspects:
- Isotherm modelling to understand equilibrium behavior
- Breakthrough curve modelling to analyse kinetics.
- Process design that addresses engineering and hydraulic considerations
Situation
A customer approached Mastermelt with a complex chemical solution containing 5 wt% copper (Cu), 100–400 ppm of palladium (Pd), 50–200 ppm of platinum (Pt), and 1% nitric acid.
The solution also contained particulates, agglomerates, and precipitates, with significant batch-to-batch variation.
Given the complexity of the mixture, traditional recovery methods were inefficient, leading to the potential loss of valuable metals in waste streams. Screening of the material’s chemistry identified the use of scavengers as the most viable option for selective recovery of Pt and Pd.
Screening Process
To determine the best approach, a flow diagram analysis of the material’s composition and behaviour in solution was conducted.
Based on this assessment, a scavenger-based trial was initiated to evaluate its efficacy in isolating Pt and Pd.
Isolating Platinum and Palladium
This time-dependent, competitive adsorption process resulted in high recovery rates for the precious metals, demonstrating the effectiveness of the functionalised scavenger in dealing with complex, multi-component solutions.
Next Steps
Once the scavenger material was loaded with precious metals, it accounted for approximately 1.3 wt% of the initial received material. The scavenger underwent further processing through Advanced Thermal Treatment (ATT) at Mastermelt’s Buxton facility.
This additional treatment helped to concentrate the precious metals into a low-volume, high-value residue.
Benefits of Advanced Treatment
The advanced treatment offered several significant advantages:
High concentration of precious metal residues in low volumes, reducing waste output
Low flammability and low toxicity of the residue, minimising environmental and safety concerns
Removal of deleterious elements, ensuring the purity of the final metal product
Facilitating the recycling of the bulk liquid phase, contributing to sustainability by reducing the need for hazardous chemical disposal.
Summary
Mastermelt’s treatment process provided the customer with an efficient, scalable solution for recovering valuable metals from what would otherwise be classified as chemical waste.
The key achievements included:
- High recovery of Pt and Pd through selective binding using functionalised scavengers.
- Efficient handling of batch variations and complex solutions containing multiple metal species.
- Effective thermal treatment to further concentrate and purify the precious metals.
Conclusion
Mastermelt successfully recovered £200,000 worth of platinum and palladium from 22 metric tonnes of solution. Without this intervention, the solution would have been discarded as waste, representing both an environmental burden and a significant financial loss.
The combination of scavenger technology and advanced thermal treatment allowed for efficient recovery, turning waste into value and underscoring the potential of functionalised scavengers in precious metal recovery operations.
This case study demonstrates the effectiveness of functionalised scavengers for selective metal recovery in industrial applications. The approach highlights the importance of tailored solutions in complex chemical environments and the significant financial and environmental benefits that can be achieved.