Self-hydrolyzing Submerged Flow Technology for Acid Coal Mine Drainage Treatment: Effective Removal of Iron Ions

Abstract

In this study, mine wastewater from Leiyang, Hunan Province was taken as the research object to investigate the effect of using the method of self-hydrolytic submerged sedimentation to treat acid coal mine drainage. It was found in this study that the removal rate of sulfate ions and iron ions from the acidic coal mine drainage stock solution at pH=2.7 was very limited by self-hydrolytic sedimentation experiments relying only on pure vertical sedimentation flow treatment, but the hydrolytic treatment could greatly improve the solution environment and promote the formation of secondary minerals of sulfate ions and iron ions in the acidic coal mine drainage, which greatly improved the removal rate of iron ions. Both suspended and precipitated materials produced in the self-hydrolysis sedimentation experiments were hydroxylated iron sulfate secondary minerals- Schwertmannite [Fe8O8(OH)8-2X(SO4)X (1 ≤ x ≤ 175)], the formation of which is inextricably linked to the low pH environment and high concentration of sulfate and iron ions in coal mine wastewater. Self-hydrophoretic submerged flow can remove iron ions from acidic coal mine drainage at low cost and high efficiency, and the total iron removal rate of this system can reach 90.93% after 24 h of treatment, which has a favorable comprehensive utilization value.