• A novel repeated approximation method accurately quantifies oolitic content in green sand by monitoring mass changes during controlled KOH reactions.
• Complete removal of oolitic deposits achieved after three KOH treatments at 300°C for 20 minutes, validated by SEM and EDS.
• The method overcomes limitations of existing KOH and H3PO4 techniques that overreact with SiO2, providing reliable and consistent results.
• Industrial implementation at Huangshi Dongbei Casting Co., Ltd. confirms its practical utility for monitoring and improving green sand reuse efficiency.