Microwave Production of Manganese from Manganese (IV) Oxide using Postconsumer Polypropylene as Reductant


  • James Ransford Dankwah University of Mines and Technology
  • Frank Adjei-Kyeremeh
  • Benjamin Kwame Dwumah
  • James Bradford Dankwah UMaT-Tarkwa
  • Pramod Koshy University of New South Wales


Microwave irradiation, Polypropylene, Calcination, Reduction, MnO2, Mn3O4, MnO, Manganese


This work investigates the production of manganese metal from MnO2 by microwave irradiation using postconsumer polypropylene (PP) as reductant. Reagent grade MnO2 was first calcined to Mn3O4 followed by reduction with pulverised postconsumer PP in a domestic microwave oven (Pioneer, Model PM-25 L, 1000 W, 2.45 GHz) in a recorded temperature range 900-1200 °C. Calcined and reduced products were characterised by XRD, XRF and SEM/EDX. The results showed that microwave irradiation is effective at calcining MnO2 to Mn3O4, evidenced by the complete disappearance of peaks of MnO2 and appearance of peaks of Mn3O4 after 40 minutes. SEM/EDX analysis revealed that calcined Mn3O4 was first transformed to MnO and later to manganese metal. The range of temperature achieved in the microwave oven was below the equilibrium temperature for MnO reduction by solid carbon and accordingly solid carbon produced from PP cannot be wholly responsible for the production of manganese metal. It is therefore concluded that the large scale production of manganese metal observed in this investigation was effected with CH4 (generated from the thermal decomposition of PP) and solid amorphous carbon as the predominant reductants, with solid amorphous carbon providing the heat energy required for the reduction. Microwave reduction of manganese oxides is therefore a potential route for diverting postconsumer plastics from landfill sites as well as decrease the amount of expensive metallurgical coke currently used in the ferromanganese process.

Author Biographies

James Ransford Dankwah, University of Mines and Technology

Senior Lecturer and Head, Minerals Engineering Department

James Bradford Dankwah, UMaT-Tarkwa

Student, Minerals Engineering Department

Pramod Koshy, University of New South Wales

Senior Research Associate, School of Materials Science and Engineering


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