Investigation of By-products from Acetylene Manufacturing for Acid Mine Drainage Remediation

We characterized carbide lime, a by-product of acetylene manufacturing, and compared it to commercial calcium oxide (CaO), which is typically used to treat AMD. Chemical and X-ray diffraction data revealed that the carbide lime was a calcium-rich lime. Morphological analysis indicated that it differed from commercial CaO in its morphology, having a layered structure. The presence of functional groups among the samples was confirmed by a Fourier transform infrared spectral study. Physical characterization, including nitrogen adsorption-desorption isotherm and particle size distribution demonstrated that the carbide lime had greater surface area and finer particle size than the commercial CaO. Jar tests were used to evaluate the effect of the carbide lime and CaO loading on actual AMD. The optimum quantity of carbide lime for treating the AMD was 0.4 g/l, which increased the pH and reduced the metal and sulphate concentrations to acceptable levels. The carbide lime showed superior acid-neutralizing and contaminant diminution at all studied loadings. Additionally, an Imhoff cone test confirmed that the sludge produced using carbide lime settled better that that produced using CaO powder.