Control of Minor Elements (2D1)

Project Status: Complete
Project Participants: ANSTO, CSIRO, University of Queensland
Project Leader: Sharif Jahanshahi (CSIRO)

The behaviour of minor elements plays a key role in the overall economic and environmental performances of processes used for the extraction and refining of minerals to metal products. The current knowledge and understanding of the deportment of minor elements between phases during mineral processing and downstream processing of concentrates are limited and insufficient to allow development of practices for optimum recovery of valuable components and safe disposal of toxic elements. This project brought together world-class expertise in mineral processing, hydrometallurgy and pyrometallurgy to address the growing interest by the industry in better control and management of dispersion of toxic and hazardous elements.

This project aimed to quantify the deportment of various minor elements across mineral processing and metal production value chains, so as to develop optimum flowsheets and practices for treating mined minerals to final metal products. The other key activity was development of predictive models for assessing the leaching behaviour of mineral phases/waste products under natural environment, so that the stability of toxic and hazardous elements in tailings and slags could be assessed.

The research objectives were to:

• Develop an improved understanding based on laboratory and plant observation, and thermodynamic modelling for the deportment of minor elements between phases and process streams in mineral processing plants.
• Develop an understanding of the behaviour of host minerals with the associated minor elements and Naturally Occurring Radioactive Materials (NORM) for a wide range of process and environmental conditions.
• Develop models of the existing processes and apply these in defining strategies for better control over in the deportment of these materials across the whole cycle of mineral processing including waste streams, environmental management, and on-use.
• Explore alternative flow sheets for removal and safe disposal of these materials.
• Develop kinetic models that link industrial and regulatory leach procedures with the behaviour of materials in real systems and allow more reliable assessment of environmental stability of various materials.
• Establish and extend a collaborative network of researchers and technologists in the field. Explore globalisation of the concepts.

During 2007/8 documentation of the findings from the high temperature experimental study on thermodynamics of selenium and tellurium in metallurgical slags was completed and a PhD thesis was produced. Technical papers were also drafted and two were published. The published data on the behaviour of a number of minor elements in pyrometallurgical systems was used for validation and refinement of the Multi-Phase Equilibrium model developed by CSIRO.

The initial focus of this project was on processing of copper or nickel sulfide ores, which are being processed in Australia . Extension of this work to encompass the processing of lead/zinc ores could be carried out as part of the second phase of this project.