A Rapid and Cost-Effective Method for Bench Screening ofGeochemical Performance and Disposal Options for High-SulfideTailings

摘要

The underground Neves Corvo copper-tin mine in southern Portugalrncurrently disposes of its tailings in a ‘traditional’ wet tailingsrnimpoundment. With the development of new technologies for preparationrnand transport of thickened tailings or paste, alternative tailings disposalrnoptions have become available that provide a more sustainable waterrnmanagement system and a higher degree of environmental protection. Inrnaddition, growing European resistance towards subaqueous disposal mayrnwell result in mandatory use of dry disposal methods in the near future.rnTwenty-four tailings disposal alternatives were evaluated through arncost-effective and easily-implementable bench-scale geochemicalrnscreening program conducted at site. Since the tailings are pyrite-rich andrnhighly acid generating, particular emphasis was placed on monitoringrnlikely indicators of sulfide oxidation under the various simulated disposalrnscenarios. Dependent parameters investigated as part of the programrnincluded moisture content, use of alkaline additives (lime, cement), usernof a bactericide, and agitation. Response parameters included paste pH,rnspecific conductance, and temperature as indicators of oxidation.rnThe testing was carried out for 30 weeks. Results indicate that arnnumber of relationships between the geochemical stability of the samplesrn(ie sulfide oxidation) and sample characteristics can be readily identified.rnBased on the results of the screening program, a limited number ofrntailings mixtures have been selected for further long-term testing in fieldrnweathering cells to aid in the identification of the optimal mix design forrnfuture tailings disposal at the Neves Corvo Mine. This type of testingrnprovides an inexpensive and reliable methodology for semi-quantitativerncomparison between tailings disposal alternatives, in particular atrnlocations where more rigorous evaluation through long-term, fullyrnreplicated testing is not immediately feasible.