REMOVAL OF METALLIC MERCURY FROM CONTAMINATED TAILING BY THE FLOTATION PROCESS

摘要

A method for removing metallic mercury fromcontaminated tailing, using the flotation process, is described. Inorder to define some relevant parameters for the mercuryflotation system, microflotation and electrophoretic mobilitytests were carried out on (pure) metallic mercury in the presenceof several surfactants. Based on the results obtained fromfundamental studies a series of bench scale flotationexperiments with mercury containing tailings from two wetlandsites in Brasil were done. The results of microflotation tests withmercury showed that by using cetyl trimethyl ammoniumbromide, an increase in mercury flotability is observed in dieacid pH range, whereas in the presence of potassium oleate thehighest mercury flotability was found in the alkaline pH region.The mercury flotability using potassium amyl xanthate wasimproved by the addition at sodium dithionate as an activator.The bench scale flotation tests with contaminated tailings fromPoconé (brazilian wetland site) showed a recovery of 70 percentwhen sodium dithionate was used as activator and potassiumamyl xanthate as collector The resulting coefficient ofseparation is around 60 percent. However, the results of theflotation experiments with fine fractions from amalgamationtailings from Peixoto de Azevedo (brazilian wetland site)showed a low mercury recovery (32 percent).The results fromthis work suggest that since in the Poconé site tailings, themetallic mercury is not completely associated ~ the finerparticles, the flotation process to recover the metallic mercuryseems very promisor.