What are the main application segments for potassium hexafluorosilicate beyond traditional uses?

What are the main application segments for potassium hexafluorosilicate beyond traditional uses?
Potassium hexafluorosilicate is produced mainly from fluorosilicic acid, a by-product of phosphate fertilizer and wet-process phosphoric acid plants. This linkage means its cost structure is heavily influenced by phosphate rock quality and the efficiency of fluorine recovery. In China, many producers are integrated with phosphate fertilizer operations, allowing them to monetize a waste stream. The reaction with potassium chloride or potassium carbonate is straightforward, but purity control is critical for higher-value applications. Industrial-grade material (typically above 98% purity) is used in smelting and glass, while optical and phosphor-grade material commands a premium. Drying is energy-intensive, especially for filter cake with around 35% moisture, and corrosion-resistant equipment is required, adding to capital and maintenance costs. These factors create a wide price band between commodity and specialty grades.