Study On Ore Body Distribution And Associated Elements Occurrence Of High-speed Iron Gibbsite In Central Guangxi

The iron-rich gibbsite type bauxite deposit in Central Guangxi is located in Yongjiang basin,southwest of South China block.It is the only large gibbsititic karst bauxite deposit in China.The gibbsite nodules are scattered in loose laterite,and are mainly composed of gibbsite,kaolinite,hematite and a small amount of zircon and quartz.Previous studies mainly focused on the geological settings and metallogenic regularities of this bauxite deposit.However,the distribution pattern and control of ore bodies and the host minerals of some critical elements in the bauxite deposit are less understood.This paper aims to answer these questions through detailed field geological survey and in-situ geochemical analysis.The gibbsitic bauxite deposit in occurs in the Quaternary laterite overlying on the platform and low hills in the karst plain of the Yongjiang Basin.The profiles usually are composed of three layers,i.e.carbonate bedrock,clay layers,gibbsite nodule-bearing layer and topsoil from bottom to top.Five bauxite districts in Central Guangxi are selected for ore body analysis,and it is found that the thickness of ore body,ore bearing capacity and grade of Al₂O₃generally increase with the elevation of mining area.The low-lying area near the high altitude is most conducive to the development of iron-rich gibbsitic bauxite,due to favorable leaching conditions.The elements Li and Ga mainly occur in clay minerals;while the enrichment of Ga is also controlled by hematite.V element mainly occurs in hematite;The Sc element mainly occurs in hematite and zircon via ion replacement;Cr mainly exists in hematite in the form of ion adsorption;TiO₂ and Al₂O₃ play an important role in the enrichment of Nb and Ta;Hf,Th and REE,especially the heavy REEs,in bauxite are mainly enriched in zircon.