The bauxite exploited in southern Venezuela is mainly gibbsitic. As far as I know it is treated with concentrated NaOH, caustic soda, not with HCl, being Al soluble in this strongly alkaline solution. Fe will not be attacked by NaOH, mainly because it already in the form of goethite or limonite.
We have carried out extensive studies on acid leaching of gibbsitic bauxite. The results are very encouraging with respect to reduction in iron and enrichment in alumina content. By this technique we can produce high grade high alumina low iron bauxite can be used in non metallurgical applications.