Dear Dr. Lwazi Charles Mahlalela ,

I suggest you to have a look at the following papers:

-Removal of iron and titanium contaminants from Jordanian Kaolins by using chemical leaching

M. Gougazeh

Journal of Taibah University for Science, DOI:10.1080/16583655.2018.1465714 (2018)

Available on RG at: https://www.researchgate.net/publication/325079319_Removal_of_iron_and_titanium_contaminants_from_Jordanian_Kaolins_by_using_chemical_leaching

-Chemical treatment of kaolin. Case study of kaolin from the Tamazert– Jijel mine

Mohamed Chouafa, Abdelaziz Idres, Ahcène Bouhedja, Korichi Talhi

Mining Science, vol. 22, 171−180 (2015)

Available at: http://www.miningscience.pwr.edu.pl/Chemical-treatment-of-kaolin-Case-study-of-kaolin-from-the-Tamazert-Jijel-mine,61286,0,2.html

Best regards, Pierluigi Traverso

Hi

In my view chemical reduction you can perform.

To decrease aluminium concentration use conc HCl, for iron you can oxidize from Fe2+ to Fe3+ , on other no need to remove other impurities.