Study On A Lab-scale Successive Alkalinity-Producing System For The Treatment Of Acid Mine Drainage

Coal mining turned the regional groundwater into acid mine drainage,which further pollutes the surface water and then destroys the ecological environment. By comparing the existing AMD active method with passive method, calcining and transnaturing carbonate rocks to confirm the optimal calcining conditions to improve the effect of AMD method, then summarizing the advantages and disadvantages, application conditions as well, of existing biological and non-biological techniques, to establish the SAPS. Appling the modified carbonate rocks to the SAPS to inspect its applicability, adjusting the entering water parameters to observe the system process conditions, and improving the system according to the performance to build a whole set of SAPS with the better tolerance and stability, which comes to below conclisions:(1)Carbonate rock is beginning to decompose at 750 degrees, it still keeps a contain particle strength even after being calcined 2 hours. In the shake flask test, 750 degrees calcined modified carbonate rock can wipe off more than 99 percent Fe2+、Mn2+,Cu2+,Ni2+, Cd2+ of the AMD after 15 hours of its reaction, which overcomes the disadvantage of a bad wiping effect on Mn of ordinary carbonate rock.(2) In the SAPS, the processing capacity calcined carbonate rock system to AMD is only slightly higher than the ordinary rock system. After increasing the entering water C/S =2.0、HRT=48h, the water quality improved, while the system instantaneous water Fe consistence increases gradually out of the HRT control. When pH=2.0, the microbe in mud is severely inhibited. In the SAPS anaerobic environment, pH upgrade is of inhibition and removal rate of each ion is not high in instantaneous water.(3) Increasing Fe2+ and sulfate radical in entering water, adding the sedimentation pond and neutralization pond can make the system maintain a stable effect of effluent. The micropopulation breeding in the sedimentation pond reacts further with waste water which brings the pH of the whole system more than 8.0, and sulfate radical and each metal ion are 100 percent removed. So as to put forward the whole acid mine drainage handling technique of AMD clean-up step by step.(4) With the combination of PHREEQC imitation and the reality infers metal ion removal mechanism that Fe would come into goethite and hematite, Cu,Cd would mainly become into metal sulfide or being removed by sorption, and Ni would totally precipitate in forms of hydrate only with the condition of PH>8, and Mn would being removed by reaction only when there exist no other ions in the waste water.