Ermittlung geeigneter Verfahren zur Reinigung ammoniakalischer wolframhältiger Laugen

Translated title of the contribution: Evaluation of appropriate purification techniques for ammoniacal tungsten-loaded solutions

Christina Sobotka

Research output: ThesisMaster's Thesis

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Abstract

Due to a sustainable resource management it is very important to develop new secondary routes in order to recover waste materials. The lack of primary sources in Europe makes the recovery of refractory metals particularly attractive. More than 60 % of tungsten is used for the production of hard metals. The main component of hard metals is tungsten carbide. A new process was developed to recycle hard metal soft scraps (grinding sludge and unsintered scrap) from the hard metal production. This process includes an oxidizing treatment (roasting) followed by an ammoniacal leaching. The recovery of tungsten via such a route is not carried out in any established process all over the world. The purity of the generated secondary product has to be comparable with one from the primary production. Therefore the leach purification is one of the most important steps of the recycling process. In this work all techniques for the purification of alkaline solutions are discussed especially those for ammoniacal leachates. Furthermore the removal of impurities from ammoniacal tungsten-liquors is described in detail. It was found out that selective crystallization is generally the most appropriate technology to purify the liquor. The amount of impurities in the WO3 rises with longer leaching times of the scrap, thus the quality of the secondary product depends on the WO3 extraction rate. An optimized ammoniacal leaching process achieves a maximum WO3 extraction rate of 88 %. The product, generated after selective crystallization, is contaminated with copper, cobalt and chromium. These impurities reach contents of > 100 ppm but there are no existing specifications of maximum impurity contents for secondary tungsten raw materials.
Translated title of the contributionEvaluation of appropriate purification techniques for ammoniacal tungsten-loaded solutions
Original languageGerman
QualificationDipl.-Ing.
Supervisors/Advisors
  • Luidold, Stefan, Co-Supervisor (internal)
  • Antrekowitsch, Helmut, Supervisor (internal)
Award date16 Dec 2011
Publication statusPublished - 2011

Bibliographical note

embargoed until null

Keywords

  • tungsten
  • purification techniques
  • ammoniacal leachates
  • tungsten-loaded solutions
  • hardmetal
  • recycling
  • refractory metals
  • ammoniumparatungstate
  • APT
  • WO3

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