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Title (Primary) Effektivität der Abtrennung der Schwermetalle und von Sulfat aus Bioleaching-Prozesswässern durch Alkalisierung = Efficiency of separating heavy metals and sulphate from waters of the bioleaching process by alcalisation
Author Seidel, H.; Wennrich, R.; Morgenstern, P.; Löser, C.;
Journal Vom Wasser
Year 2002
Department UBT; ANA; SANA; SAN;
Volume 99
Language deutsch;
Abstract Process waters from waters of the bioleaching process contain a wide range of dissolved heavy metals, are high in sulphate, and have pH values in the range of 2-3. The leachates need to undergo a cost-effective water treatment procedure before they can be released into receiving waters. This study examines the efficiency of separating heavy metals and sulphate by alcalisation with Ca(OH)2, NaOH und CaCO3 on the laboratory scale as well as in a pilot plant using the example of process waters from bioleaching heavy-metal contaminated sediments. Alcalisation with Ca(OH)2 at pH 9-10 led to the precipitation of all the dissolved heavy metals in the form of metal hydroxides or mixed salts. Reaction times of 30 min were sufficient when using milk of lime. The limits for heavy metals in treated wastewaters laid down in German regulations were reached, including on the pilot scale. Sulphate was precipitated as gypsum down to residual concentrations of 1.5-2 g/L. The gypsum matrix facilitated the sedimentation and dewatering of the sludges. NaOH caused at pH 8-9 the total separation of heavy metals as hydroxides with the exception of Mn. However, because the sulphate remains in solution and Na ions are introduced, the salt load of treated waters increases. Another disadvantage is the formation of voluminous precipitates which contain large amounts of salts and which are almost impossible to dewater. Neutralisation with CaCO3 caused up to 98% of the dissolved heavy metals to precipitate. The sulphate content was reduced to just 5.6 g/L. The minimum reaction time needed was 24 h. The limits for Zn, Cd and Co in the treated waters were not reached. Irrespective of the alcalising agent used, the precipitates contained about 6-7% heavy metals in dry matter (predominantly Zn and Mn). Relatively large amounts of Al and Mg were also detected. The main component of the sludges upon alcalisation with Ca(OH)2 was gypsum (up to 70%).
ID 6018
Persistent UFZ Identifier https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=6018
Seidel, H., Wennrich, R., Morgenstern, P., Löser, C. (2002):
Effektivität der Abtrennung der Schwermetalle und von Sulfat aus Bioleaching-Prozesswässern durch Alkalisierung = Efficiency of separating heavy metals and sulphate from waters of the bioleaching process by alcalisation
Vom Wasser 99 , 39 - 52