Quartz significance for hydropower project

Quartz ($SiO_2$) has hardness 7 and is very resistant to weathering, so it is the commonest mineral in river sediments.

When sediment analysis is done for a hydropower project, the quartz percentage of the suspended load is important because:

• Quartz is harder than turbine steel (the Mohs hardness of steel is about 5-6), so quartz particles abrade and erode turbine runners, guide vanes, nozzles and needles (sediment abrasion).
• The high quartz content of Himalayan rivers reduces turbine efficiency, increases maintenance cost and shortens the life of parts.
• It decides the need for desanding basins/settling basins to remove particles larger than 0.15-0.2 mm, and the selection of turbine type (Pelton or Francis), hard coatings (tungsten carbide) and operating speed.
• Quartz-rich rock also gives strong, durable aggregate for concrete, but it is abrasive on tunnel boring machine cutters.