Comparative study of acid mine drainage using different neutralization methods

Abstract

Two-stage acid mine drainage (AMD) neutralization residue yield is 2.57 t/t acid equivalent using limestone and lime, 15.74% less than the 3.05 t/t acid equivalent yield from single-stage, lime, neutralization residue. XRD results shows that the main residue component generated by two-stage neutralization is CaSO4•0.5H2O, with a molecular weight 15.70% lower than the CaSO4•2H2O generated in single-stage neutralization. The differing amount of gypsum crystallization water from the different neutralization processes is the main cause of the different residue yields. While the actual removal rate and pH of Fe3+ are consistent with the theory, those for Zn2+, Cu2+ and Al3+ are inconsistent with the theoretical values, the error rate increasing with increasing pH. Co-precipitation with and adsorption by Fe(OH)3, mainly generated during neutralization, are the main reasons for the difference. The cost of two-stage neutralization is 16.60% less than that of single-stage neutralization when the initial reaction pH is 3.4, but the unit cost begins to increase if the initial reaction pH is raised above 3.4. When the initial pH is 4.0, the cost of two-stage neutralization exceeds that of single-stage neutralization by 4.07%.

Influence on the roof stability of EMU induced by welding deformation

“…Currently, there is little information regarding the three-dimensional thermal elastic-plastic analysis of plug welds. To verify the plug welding, the relevant study in [9] was consulted to determine the plastic strain value for a plate thickness of 2+2 mm. The beam element was used to simulate plug welding and the extracted inherent strain was applied at the welding seam.…”

The Mixture of Limes in Acid Mine Drainage Treatment

“…Type of Ore The method for AMD treatment can be classified into two: active method and passive method. The active method involves a precipitation process with alkaline chemicals such as quicklime, hydrated lime, CL, limestone, magnesium hydroxide, alkaline tailings, etc [38]. Figure 1 shows a typical method in the treatment of AMD using lime as the neutralisation agent [14].…”