Will TOMRA's laser-based sorting technology shake up HPQ processing?

• Autores: Cameron Perks
• Localización: Industrial Minerals, ISSN 0019-8544, Nº. 594, 2017 (Ejemplar dedicado a: Junio)
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • Despite HPQ having no standard processing route, there are new technologies which seek to increase sorting capabilities, making it easier for producers to separate their HPQ by impurities, Cameron Perks, IM Correspondent, finds.

    High-purity quartz (HPQ) is known for its high-tech applications: from semiconductors to solar silicon applications, HPQ has found its way into various everyday items.

    There is no standard processing route to making HPQ. Depending on end-application and starting-purity, raw quartz is processed into its high-purity form by both off-the-shelf technologies, as well as via tailor-made specialty solutions.

    In the book titled ' Quartz: Deposits, Mineralogy and Analytics', Dorfner ANZAPLAN's Reiner Haus, Sebastian Prinz and Christopher Priess, explain how based on the specific characteristics of the quartz deposit, a processing route may be achieved.

    In general, a processing route consists of the following main stages: pre-processing (mechanical), physical processing, chemical leaching and thermal treatment. For many, selective mining is where processing begins, and is a common method of sorting out which quartz will qualify for subsequent processing steps. This, as well as costly hand-sorting practices is what optical sorting has set out to replace in recent years.

    According to Haus et al. optical sorting can be applied with high efficiency down to the 3-5mm range. As the name suggests, the method is used to separate quartz fragments containing different optical properties, namely colour.

    Colour is useful, as rose quartz may indicate elevated levels of phosphorous, a deleterious element for solar application. In smoky quartz, elevated radiation levels may indicate the presence of alpha radiation sources uranium and thorium, known to cause soft error in memory devices.

    Too many impurities, commonly in the form of aluminium, iron, lithium and phosphorous will lower the end-product melting point risking premature mechanical failure when working at high temperatures, and may contaminate ultra-pure silicon metal through processes of diffusion and devitrification.