Abstract: The cobalt concentrate from Zambia were studied. Bacteria used in the leaching was ZY101， a kind of mixed bacteria which can grow normally in the system containing 30 g·L^-1 cobalt after a long time of domestication. During leaching of cobalt concentrate， the effects of surfactant Tween 80 were evaluated by measuring the pH value of solution， the electric potential value of solution， the density of Fe²⁺， the density of bacteria cell in solution and the rate of cobalt leached. The results showed that Tween 80 can improve the leaching of the cobalt concentrate and the optimal dosage is 0.01%(volume concentration). After leaching for 15 days， the rate of cobalt leached reaches 93.25%. Compared with the system of bioleaching solution without Tween 80， the rate of cobalt leached increases by 62%. During the bio-leaching of Zambian cobalt concentrate， the addition of Tween 80 exhibits good catalytic effect.

Key words: cobalt concentrate, bio-leaching solution, surfactant, Tween 80, bioleaching bacteria