Most heavy metal could be solubilized and leaching efficiency was almost constant in the pulp density range from 1% to 3% (97.8 ± 0.4% for copper, 98 ± 0.1% for zinc, 72.6 ± 1.2% for lead and 91.6 ± 0.7% for chromium, respectively). With further increase in pulp density, leaching efficiency dropped gradually. When pulp density was 10%, leaching efficiency was still efficient (80.2 ± 0.1% for copper, 87.8 ± 1.4% for zinc, 60 ± 2% for lead and 80.9 ± 2.3% for chromium) and was much higher than that treated by H2SO4 (33.5% for copper, 51.7% for zinc, 50.41% for lead and 25.7% for chromium). When pulp density was higher than 15%, final pH could hardly decrease to lower than 3.0 and only trace heavy metal could be solubilized. No great variation in nitrogen and phosphorus content was detected after bioleaching.