Bioleaching of flotation tailings is different from that of primary ore because of the residual reagents in flotation tailings.The effects of seven flotation reagents(ethyl xanthate

isopropyl xanthate

butyl xanthate

isoamyl xanthate

butylamine

2 oil and 11 oil)on the growth and activity of the strain Acidthiobacillus ferrooxidans LD1 have been studied in this paper.The results showed that all of them could depress the growth and activity of the strain At.fLD-1.From weak to strong

their inhibition effect on the strain At.f LD-1 was in following order:11# oil

2# oil

butyl xanthate

isopropyl xanthate

isoamyl xanthate

ethyl xanthate

and butylamine.It was found that the depression of collectors on the strain At.fLD-1 was stronger than that of frother

especially ethyl xanthate and butylamine.The oxidation rate of ferrous ion(Fe2+)can reach about 90% after 24 h without any flotation reagents

but the reduction of the rate was lower than 5% with 80 mg·L-1 ethyl xanthate or butylamine in culture system.With increase of reagent dosage

the depression of flotation reagents on the strain At.fLD-1 would enhance.