Research on the processing of spent magnesia-carbon refractory bricks for developing innovative recycling approaches

Sandra Königshofer

Research output: ThesisDoctoral Thesis


This PhD thesis comprises comprehensive research on the processing of spent MgO-C refractory bricks. The aim is to develop innovative recycling concepts, where secondary raw materials have not to be blended with primary raw materials or only to some extent in the production of new refractories, provided that the chemical and physical properties are comparable with refractories made of primary raw materials. Due to strict quality requirements for refractory raw materials the separation of the main components magnesia and carbon is investigated in this thesis to recover these raw materials as pure as possible. Therefore, the application of appropriate comminution methods for creating a sufficient degree of liberated particles poses a challenge. An overview about the state of the art regarding recycling is presented after an introduction in MgO-C bricks. The investigations start with experiments regarding sensorbased sorting of MgO-C and AMC bricks followed by crushing tests to study the comminution behaviour of these bricks. Exploratory processing tests are performed in the field of flotation and electrostatic separation on the basis of a comprehensive raw material characterisation. It is possible to produce a high-quality magnesia product, but the enrichment of carbon in the concentrate is limited. Due to the existence of challenging intergrowth characteristics concerning the liberation of carbon, further examinations focus on studying innovative unconventional methods such as hydrothermal processing and high voltage pulse power fragmentation that should allow an improved initial situation for subsequent separation steps compared to conventional comminution. The results of release analyses are shown in Henry/Reinhardt diagrams, the results of exploratory separation tests are represented in balances and in the Ԑ diagram according to Steiner. Last but not least examples for possible process designs are presented.
Translated title of the contributionForschungsarbeiten auf dem Gebiet der Aufbereitung von gebrauchten MgO-C Feuerfeststeinen zur Entwicklung innovativer Recyclingansätze
Original languageEnglish
  • Harmuth, Harald, Assessor B (internal)
  • Flachberger, Helmut, Assessor A (internal)
Publication statusPublished - 2015

Bibliographical note

embargoed until null


  • refractories
  • recycling
  • mineral processing

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