Untersuchung verschiedener Flotationsabgänge in Hinblick auf die Verwendung als Rohstoff für alkali-aktivierte Bindemittel

Translated title of the contribution: Investigation of flotation tailings as a precursor for alkali-activated materials

Oliver Simon

Research output: ThesisMaster's Thesis

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Abstract

Mineral wastes, produced from flotation are a problem for both environment and process owner due to potentially harmful elements e.g. sulphides as well as their huge amount. A complex waste management is needed to store those wastes in tailing ponds and to avoid acid rock drainage. In most cases the wastes are not valorised. This thesis investigates alternative utilisation of flotation tailings from iron ore and copper ore mines by using the method of alkali-activation. In order to use those tailings for alkali-activated binders, dissolution behaviour plays a mayor part, especially the dissolution of alumina, silica and calcium. The dissolution behaviour of tailings from three different mine sites and metakaolin in 5 and 10 N NaOH at 40 °C in dependence of time (ranging from 4 to 72 hours) was investigated. In accordance with Panagiotopoulou [1], high amounts were found in solution after treatment with 10 N NaOH for 24 hours: over 75 % the originally contained Al2O3 and SiO2. Also a higher dissolution resulting from higher NaOH concentrations could be verified. The tailings showed rather low solubility: less than 5 % of the contained oxides Al2O3, SiO2 and CaO of the copper-nickel ore and the copper-zinc ore tailings were in solution after 24 hours in 10 N NaOH. The iron ore tailings showed the highest solubility among the investigated tailings: more than 20 % of Al2O3 and more than 10 % each for SiO2 and CaO in 10 N NaOH. Si:Al molar ratios ranged from 1,7 to 8,0. Tailings from iron ore and copper-zinc ore flotation were used as raw materials for alkali-activated binders. Dried tailing material was mixed with different activator-solutions, consisting of NaOH, water glass and deionised water. Cylindrical samples were made from these mixtures, cured at 60 °C and tested for compressive strength. 3,5 MPa after 7 days were determined for the copper-zinc tailing mixture. For the iron ore tailings, only low compressive strengths (< 2 MPa) could be achieved by solely adding activator-solution. The addition of silica sand also didn’t improve strength. By adding 10 % of metakaolin, 48 MPa were determined after 28 days of curing at 60 °C. Origin of that strength might either be water glass bond or the formation of CSH-phases. The bond-type was not investigated. The compressive strength of both materials would allow utilisation as backfill material in underground mining, but further investigation under service temperature and parameters such as durability, water resistance and leachability need to be determined.
Translated title of the contributionInvestigation of flotation tailings as a precursor for alkali-activated materials
Original languageGerman
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Harmuth, Harald, Supervisor (internal)
Award date28 Jun 2019
Publication statusPublished - 2019

Bibliographical note

embargoed until null

Keywords

  • Geopolymer
  • binders
  • alcali activated
  • AAM
  • flotation
  • tailings
  • dissolution
  • metakaolin
  • mining

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