Carbothermic reduction roasting for processing of ferruginous chromite ore using conventional and microwave heating

Sunil Kumar Tripathy, Y. Rama Murthy, Nikkam Suresh, Lev O. Filippov

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11 Scopus citations


The present study investigates the recovery of chromite from a low-grade ferruginous ore through the carbothermic magnetization route using conventional and microwave heating sources. The carbothermic magnetization of ore is studied in both a horizontal tube furnace and a microwave oven by varying different process variables. The main objective of the study is to enhance the magnetic susceptibility of iron-bearing gangue minerals to enable the separation in a magnetic field. Alteration of crystalline structure and magnetic property of these minerals enables separation of low-grade ore by using magnetic separation. It is found that low-grade ferruginous chromite ore can be upgraded by reduction roasting, and 61.2% Cr2O3 was recovered with a chromium-to-iron ratio of 1.93 from a feed chromium-to-iron ratio of 1.01. The optimum result is achieved at a roasting temperature of 800 °C, with a roasting time of 60 min and a reductant dosage of 7.5%. Similarly, under microwave radiation, the chromium-to-iron ratio was upgraded to 1.81 with a recovery of 22%Cr2O3. The optimum result achieved under microwave radiation is at a microwave power of 900 W and exposure time of 7.5 min, with a reductant dosage of 10%. The findings of these two processing routes are discussed through characterization tools.

Original languageEnglish (US)
Pages (from-to)2234-2247
Number of pages14
JournalAdvanced Powder Technology
Issue number7
StatePublished - Jul 2021
Externally publishedYes

Bibliographical note

Funding Information:
The authors are thankful to the management of Tata Steel Ltd. for the support and permission to publish this study. Also, thanks to Mr. S Prasad and Mr. S Z Khan for their internship under “Mind over Matter” program at Tata Steel. SKT would like to acknowledge Labex Resources 21, supported by the French National Research Agency through the national program “Investissements d’Avenir” [reference ANR–10–LABX–21], for his fellowship.

Publisher Copyright:
© 2021 The Society of Powder Technology Japan


  • Carbothermic reduction roasting
  • Ferruginous chromite ore
  • Magnetic separation
  • Microwave heating


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