Production of high purity silica by microfluidic-inclusion fracture using microwave pre-treatment

Buttress, A.J.; Rodriguez, J.M.; Ure, A.; Ferrari, R.S.; Dodds, C.; Kingman, S.W.

Abstract

© 2018 Demand for high purity silica used in component manufacture is set to outstrip current supply in the near future. As such, alternative processing routes to feed-stock materials suitable for use in lighting and solar cell fabrication are required, without having to rely on reject material from semi-conductor manufacture. In this work, we report a facile, environmentally friendly method of producing quartz powder with a total residual impurity level of 30 ± 3 ppm from whole pebbles having an initial impurity level of 158 ± 22 ppm. This has been achieved using a metallurgical upgrading process incorporating microwave pre-treatment, crushing and milling, High Intensity Wet Magnetic Separation (HIWMS) and acid leaching. This process yielded a quartz powder having an 80% reduction in residual impurities compared to the untreated quartz pebbles. Pre-treatment of whole quartz pebbles in a multimode microwave cavity for 10 min yielded a reduction of the residual elemental impurity content associated with micro-fluidic inclusion sites containing calcium, potassium and sodium of 84, 78, and 50% respectively. Statistically significant reduction in residual aluminium phases was also observed (83%) compared to the as received material to below the IOTA® specification for Ultra High Pure Quartz produced by Sibleco. Mechanistically, this has been achieved by selectively heating impurity containing micro-fluidic inclusion sites. Resulting in their explosive decrepitation and enabling removal of the impurities in subsequent processing steps. It has been concluded that natural quartz pebbles can be upgraded through a combination of microwave treatment, magnetic and chemical refinement to produce a viable feedstock for the subsequent production of solar grade silicon.

Citation

Buttress, A., Rodriguez, J., Ure, A., Ferrari, R., Dodds, C., & Kingman, S. (2019). Production of high purity silica by microfluidic-inclusion fracture using microwave pre-treatment. Minerals Engineering, 131, 407-419. https://doi.org/10.1016/j.mineng.2018.11.025

• Journal Article Type: Article
• Acceptance Date: Nov 14, 2018
• Online Publication Date: Dec 6, 2018
• Publication Date: Jan 15, 2019
• Deposit Date: Jan 7, 2019
• Publicly Available Date: Dec 7, 2019
• Journal: Minerals Engineering
• Print ISSN: 0892-6875
• Electronic ISSN: 0892-6875
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 131
• Pages: 407-419
• DOI: https://doi.org/10.1016/j.mineng.2018.11.025
• Keywords: Control and Systems Engineering; Geotechnical Engineering and Engineering Geology; Mechanical Engineering; General Chemistry
• Public URL: https://nottingham-repository.worktribe.com/output/1409018
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0892687518305090