Abstract: The gold recovery rate of a certain gold ore concentrator was 91.25%，and the tailings grade was 0.15g/t.To further increase the gold recovery rate and reduce the tailings grade，this study car⁃ ried out a systematic process mineralogical diagnosis.Through a comprehensive analysis of the flotation raw ore and tailings，the occurrence state of gold，the process characteristics of the main gold-bearing miner ⁃ als，and the loss mechanism of gold in the process were identified.Research has found that the gold miner⁃ als in the raw ore have a relatively small particle size，mainly fine particles.31.87%of the gold exists in pyrite in the form of fine particle inclusions，and about 6.27%of the gold is closely related to metal oxides and silicate gangles.The fine-grained gold associated with sulfides in the tailings has not been effectively recovered，followed by the loss of encapsulated gold in easily mudned silicate gangue due to the interfer ⁃ ence of mine mud.Based on the above understanding，a process optimization plan centered on adjusting the fineness of grinding，optimizing the flotation reagent system，and strengthening the dispersion pretreat⁃ ment of slime was proposed.Industrial tests show that after optimization，the total recovery rate of gold has increased to 93.79%，and the grade of tailings gold was decreased，with significant annual economic bene ⁃ fits.This study confirmed that process mineralogy plays an irreplaceable and crucial role in accurately diag ⁃ nosing bottlenecks in mineral processing and guiding process optimization.

Key words: process mineralogy, occurrence state, recovery rate, flotation loss mechanism of gold ore