Everyday increasing mineralogical complexity and reducing the grade of the sulfide mineral resources have led to many difficulties in obtaining technically and economically viable concentrates. The integration of sphalerite, galena and pyrite minerals together in some parts of the sulfide and oxide ores has made it impossible to produce high-grade flotation concentrates. Bioleaching is highly capable of extracting valuable minerals from comlex and low-grade mineral resources. Therefore, in this study, the feasibility of the biological extraction of zinc from a cumulative low-grade lead-zinc flotation concentrate was investigated in a semi-industrial-scale continuous bioleaching system. After the adaptation of the thermophilic iron and sulfure oxidizing bacteria to the concentrate in shake-flasks and subsequently, in 50 L stirred reactors, the continuous bioleaching process was initiated at 15% solid content and in 15-days residence time. The results showed that 83% of zinc was recovered using an industrial Norris medium (containing chemical fertilizers) and initial pH = 1.8. The iron concentration of the pregnant solution obtained from the bioleaching stage, was 5.6 g/L. So, it was precipitated using ammonia-jarosite method with 83% efficiency. Then, the low-iron pregnant solution was purified by solvent-extraction applying D2EHPA extractant which was previously saponified (25%) by sodium hydroxide. The optimum condition for zinc extraction was obtained as 25 °C, pH=3.5, 12 min stirring time, 30% extractant percentage and 1:1 organic to aqueous phase ratio. Once the optimum condition was determined, the McCabe-Thiele diagram was plotted and finally, two extraction stages were proposed for the complete extraction of zinc from the aqueous solution.