To achieve the efficient exploitation of refractory bismuth-bearing polymetallic ores and the comprehensive recovery of bismuth resources, the technical challenges associated with high-carbon and high-calcium bismuth middlings were addressed, including strong interference from high-carbon and high-calcium gangue, a complex flotation pulp environment, and the inhibition of bismuthinite floatability caused by residual reagents from prior separation stages. An innovative combined impurity removal process of "reagent removal pretreatment-flotation bismuth extraction-acid leaching purification" was proposed. Process mineralogy analysis and bismuth recovery experiments were systematically conducted, and the process parameters were systematically optimized. The research results show that after conditioning with hydrochloric acid and reagent removal treatment with activated carbon, the high-carbon and high-calcium bismuth middlings undergo flotation bismuth extraction using sodium silicate and lime as depressants, butyl xanthate as the collector, and No.2 oil as the frother. Subsequently, acid leaching is performed with hydrochloric acid at a mass concentration of 18% under conditions of a leaching temperature of 30 ℃ and a liquid-solid ratio of 2∶1 for 8 min. Ultimately, a qualified bismuth concentrate with a yield of 17.07%, a bismuth grade of 19.91%, and a bismuth recovery of 74.75% can be obtained. This process precisely overcomes the key technical bottleneck in the recovery of high-carbon and high-calcium bismuth middlings. The reagent removal pretreatment with activated carbon accurately eliminates the inhibitory effect of residual reagents. Subsequently, the flotation process achieves efficient separation and enrichment of bismuth minerals from gangue minerals such as calcium carbonate. Finally, acid leaching realizes the selective removal of residual impurities, thereby significantly enhancing the quality of the bismuth concentrate and ultimately achieving efficient impurity removal and purification of these high-carbon and high-calcium bismuth middlings.