Thermal and Mechanical Activation in Acid Leaching Processes of Non-bauxite Ores Available for Alumina Production—A Review

  • Thierno Saidou BarryEmail author
  • Turan Uysal
  • Mustafa Birinci
  • Murat Erdemoğlu
Review Article


The rapid development of the global alumina and aluminum industry is straight coupled with the demands and the needs of these materials. Nowadays, the only well-known accessible resources to produce alumina and aluminum are bauxite ores. But bauxite ores are limited, and the remaining exploitable reserves do not have high contents in alumina. In countries where there is little or no bauxite reserves or where the recovery of existing bauxite ores to produce alumina with the Bayer process are not economic, alternative resources for alumina have been explored. The most attractive resources for replacing bauxites are aluminosilicate clay minerals and coal fly ash. The important processes developed for the recovery of alumina from these sources are acid leaching and alkaline leaching processes. The acid leaching is known as the most efficient in which thermal and mechanical activation are included for improving the performance of the process. The objective of this review is to give a comprehensive insight on the production of the alumina from thermally or mechanically activated clays and coal fly ash by hydrochloric, sulfuric, and nitric acid leaching processes.


Alumina Non-bauxites ores Acid leaching Thermal activation Mechanical activation 



The authors would appreciatively like to acknowledge the Scientific and Technological Research Council of Turkey (TÜBİTAK) for financing this study by the project with grant No. 214M432 and İnönü University Scientific Research Projects Unit for support with grant No 2015/44G.

Compliance with Ethical Standards

Conflict of Interest

The authors declare that they have no conflict of interest.


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Copyright information

© The Society for Mining, Metallurgy & Exploration 2018

Authors and Affiliations

  1. 1.Department of Mining, Metallurgy and Materials EngineeringLaval UniversityQuebec CityCanada
  2. 2.Department of Mining EngineeringInönü UniversityMalatyaTurkey

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