Wiederaufbereitung von Bergehalden und Schlickerteichen der Kaolinaufbereitung

Translated title of the contribution: Reprocessing of waste rock and tailings from kaolin production

Valentin Spiess

Research output: ThesisDoctoral Thesis


The present dissertation focuses on the resource-efficient utilization of industrial mineral deposits by exploiting historical processing residues, exemplified by the Kriechbaum kaolin deposit. The processing of raw kaolin from primary deposits generates significant amounts of silica- and feld-spar-rich tailings, which are relatively low in iron by nature. These were deposited at the Kriech-baum site either as fine middle fractions in the TSF (tailing storage facility) or as coarse fractions in waste rock dumps. The chemical and mineralogical differences of these materials are due to the mineral-specific particle size distributions of their main mineral phases: quartz, potassium feld-spar, kaolinite, and muscovite, leading to different options for utilization.
This work encompasses studies conducted at the Chairs of Mineral Processing and Geology and Economic Geology at the Montanuniversität Leoben, as well as with domestic and international re-search partners. The primary goal was to conceptually develop a beneficiation process for high-quality silica sands and kaolinite-rich materials for the ceramic industry from the raw materials of the TSF and the waste rock dumps. Resulting by-products (kaolin, feldspar, mica, and pre-concentrates of the heavy mineral fraction) were characterized for potential utilization.

The research began with a thorough characterization of the processing residues using the "feature class analysis" method. This involved quantitatively combining geochemical analyses within de-fined feature classes with the physical feature values of this fractionation. Based on this, systematic processing trials were conducted, including crushing (rod and VSI impact mills), attrition, mag-netic separation (HGMS, SLon type VRPHGMS, DHIMS), mica and feldspar flotation, sensor-based sorting (VIS), and electrostatic separation (high tension roll separator).
The raw materials from the waste rock dumps were analyzed according to their mineral-specific natural breakage characteristics, followed by milling tests with rod- and VSI impact mills. Kinetic attrition studies were conducted on raw materials from the TSF.
Magnetic separation trials aimed at separating paramagnetic heavy minerals and mica were con-ducted using various separator types at both laboratory and pilot scales, in dry and wet modes. The outcomes were evaluated using mass and metal balances as well as partition curves, based on susceptibility analyses.
Flotation tests on all relevant raw materials, considering various pre-treatments (e.g., milling or combination with sensor-based sorting), were a major focus. Mica flotation using cation-active collectors was compared to physical separation. Feldspar flotation was performed both with and without HF activation, examining the influence of pH value and reagent dosage on recovery and flotation kinetics.
Concentrates were chemically and mineralogically analyzed and compared with commercially available products from primary raw material sources as a benchmark.
Translated title of the contributionReprocessing of waste rock and tailings from kaolin production
Original languageGerman
Awarding Institution
  • Montanuniversität
  • Flachberger, Helmut, Supervisor (internal)
  • Melcher, Frank, Co-Supervisor (internal)
  • Rosenkranz, Jan, Assessor B (external), External person
  • Raith, Johann, Assessor A (internal)
Publication statusPublished - 2024

Bibliographical note

embargoed until 01-05-2029


  • mineral processing
  • kaolin
  • silica
  • tailings
  • reprocessing
  • flotation
  • magnetic separation
  • raw material characterization

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