Cyclone process for heavy metals decontamination of sediments

During a campaign of sediment sampling at a South-Western Sardinia lagoon, which joins the sea, some sediment samples have been collected and tested in order to fi nd the presence of heavy elements pollution, through some grain-size and chemistries analysis. A considerable concentration of those elements, over the limits previewed by the Italian law, was found particularly in the fi ne fractions. The contamination of those sediments by heavy metals depends on numerous factors, such as the presence of old mines and industrial waste collection basins. The possibility of reducing the presence of the polluting elements through a cyclone process has been studied on the sediment samples collected. Therefore, on every sample collected and on a reconstituted representative sample a cyclone process has been set up. With a cut-size d50 about 30 ?m it is possible to get an overfl ow and an underfl ow. The overfl ow has been constituted by a pre-concentration of heavy elements that will be eliminated subsequently by a suitable hydrometallurgical process. The underfl ow has shown a pollution grade under the law limits.