Tillämpning av natriumcitrat vid svavelkisflotation på högsvavlig avfallsprodukt i Aitik

The Siilinjärvi acid and fertilizer plant in Finland, belonging to Yara International has a requirement for pyrite as feed material. Due to forthcoming exhaustion of Pyhäsalmi mine and the current supply to the plant, the possibility of pyrite production and sale to Yara is being investigated. The Aitik copper mine is owned and operated by Boliden AB since the discovery of the Aitik- Salmijärvi sulphide mineralisation in 1930. In the Aitik concentrator, valuable metals is being separated from gangue through flotation. Rougher and cleaner circuits produces two tailing products, "high sulphur" and "low sulphur". The HS product was used as feed material for all laboratory tests due to its high pyrite content. Two methods is available to allow pyrite flotation, sulphuric acid and soda ash, both of which removes calcium ions existing on the particle surfaces that prevents it from becoming hydrophobic. Trisodium citrate have shown similar characteristics in other studies when separating Cu-Pb and was decided to be evaluated as a potential method for pyrite flotation.Results indicates the HS product in Aitik concentrator is suitable for flotation and that all methods tested, has potential to produce a high quality concentrate to meet eventual requirements. Using sodium citrate in the flotation process contributed to a dry froth and adding nasfroth was needed to make the method work. Applying the sodium citrate method at slightly acidic conditions, produced very high-quality pyrite concentrates in terms of grade and particularly pyrite recovery. Both sulphur analysis using Leco instruments by ALS and elementary analysis using X-Ray Fluorescence in Aitik concentrator, has shown questionable results. The calibration used for pyrite analysis in Aitik, is in need of additional pure pyrite concentrates to minimize standard deviation and increase its accuracy. Results provided by ALS showed sulphur grades exceeding the theoretical sulphur grade in pure pyrite quite extensively, and was thought not to be elementary sulphur due to its extent. The matter was discussed, but the grades remained the same in reanalysis and the true reason of the high sulphur content remains unknown.Validerat; 20160607 (global_studentproject_submitter