Abstract: To address the technical bottlenecks of low micro-fine gold recovery, large fluctuation in tailing grade, and prominent pungent odor of reagents in the existing xanthate + dithiophosphate collector system at a gold mine in Shandong Province, this study investigates the flotation application and action mechanism of a novel collector Ruijin 212. Based on a systematic process mineralogy analysis that clarifies the ore mineral composition, gold occurrence modes and dissemination characteristics, reagent type screening and dosage optimization were carried out through laboratory flotation tests, and its industrial adaptability was verified via a 20-day commissioning trial. The microscopic interaction mechanism was elucidated on the basis of coordination chemistry theory.The results showed that gold occurred primarily as discrete native gold and in gold-bearing pyrite. The −0.020 mm fraction accounted for 31.19% of the ore, which was identified as the principal cause of the poor recovery achieved using conventional collectors. Under laboratory conditions, Ruijin 212 outperformed the xanthate + dithiophosphate system across all dosage gradients: at a dosage of 90 g/t, it achieved a gold recovery of 95.15% and a concentrate gold grade of 13.03 g/t. In industrial production, Ruijin 212 reduces the unit reagent consumption by 23.1%～38.5%, lowers the average tailing gold grade from 0.21 g/t to 0.15 g/t, and increases gold recovery by approximately 2 percentage points. The stability of process indexes and concentrate quality are improved simultaneously, and the irritating odor at the production site is completely eliminated. Calculated based on 330 days of annual operation and a gold price of 800 yuan per gram, the optimal reagent regime can raise the annual comprehensive benefit by 7.2943 million yuan. Mechanism analysis reveals that Ruijin 212 enhances chemisorption on gold-bearing pyrite through strengthened σ-π synergistic bonding, and forms strong dispersion forces with native gold by virtue of its high molecular polarizability. This dual mechanism realizes simultaneous and efficient collection of both gold-bearing sulfides and discrete native gold. With remarkable technical, economic and environmental advantages, this reagent can provide technical support for quality improvement, efficiency enhancement and green upgrading of similar gold mines.