Extraction Of Arsenic And Mercury From The Manganese Residue With Pesa And Ma/Aa

A certain amount of manganese slag was digested using aqua and H2SO4, then, in HCl-thiourea-VC medium, As and Hg in the sample were determined by hydride-generation atomic fluorescence spectrometry (HG-AFS). The negative high voltage of photomultiplier was270V for both As and Hg and the lamp currents were45mA and10mA for As and Hg, respectively. The detection limit of the method for As was0.0135μg/L, with RSD of1.9%and recoveries of98.8%-105%. The detection limit for Hg was0.0090μg/L, and its RSD was2.8%, with recoveries of91.7%-96.0%. The precision and accuracy of the method met the requirement of simultaneous determination of As and Hg in manganese slag with quick, accurate, and sensitive merits.Manganese slag as a study material and poly epoxy succinic acid (PESA) as extractant, the effects of pH, concentration of PESA, sludge to liquid ratio on the extraction efficiency of arsenic in the manganese slag were investigated. The experimental results showed that the As extraction efficiency of PESA was excellent as compared to acrylic-maleic anhydride copolymer. When the pH was1, ratios of manganese slag to liquid was1:200, the concentrations of extractant was50mol/L, stirring time was60min and the solution was settled overnight, As extraction efficiencies reached78.3%. Manganese slag as a study material, poly epoxy succinic acid (PESA) and acrylic-maleic anhydride copolymer (MA/AA) as extractants, respectively, the effects of pH, concentration of PESA and MA/AA, sludge to liquid ratio and stirring time on the extraction efficiency of mercury in the sludge were investigated. The experimental results showed that the Hg extraction efficiency of PESA was better than that of MA/AA. When the pHs were6and9, ratios of sludge to liquid were1:250and1:300, the concentrations of both extractants were30mol/L, stirring time was60min, Hg extraction efficiencies of PESA and MA/AA were62.7%and27.6%, respectively. After the manganese slag was extracted by PESA, it met the requirements of the standards of hazardous wastes and the toxics identifications of leaching materials.