MINERALOGY, GEOCHEMISTRY AND LEACHING BEHAVIOR OF THE SOROAKO NICKELIFEROUS LATERITE DEPOSIT, SOUTH SULAWESI, INDONESIA

• Main Authors: , SUFRIADIN, , Prof. Ir. Panut Mulyono
• Format: Theses and Dissertations NonPeerReviewed
• Published: [Yogyakarta] : Universitas Gadjah Mada 2013
• Subjects: ETD
• Online Access: https://repository.ugm.ac.id/119225/; http://etd.ugm.ac.id/index.php?mod=penelitian_detail&sub=PenelitianDetail&act=view&typ=html&buku_id=59221
• Institution: Universitas Gadjah Mada

Soroako nickeliferous laterite deposit, located in the central region of Sulawesi Island, is the primary source of Ni in Indonesia. This deposit has been mined and processed using conventional smelting techniques in site by PT. Vale Indonesia. Soroako Ni laterite deposit consists of two ore types on the basis of its different serpentinization degree of ultramafic bedrocks, namely west ore and east ore type. The west ore type is derived by chemical weathering of unserpentinized peridotite while the east ore type is formed by chemical weathering of moderately to highly serpentinized ultramafic rocks. This study reports on mineralogical and geochemical results with the principal aim at deciphering the relationship between parental peridotites particularly the role of serpentinization degree of ultramafic protolith for development the overlying nickeliferous laterite ores. Leaching experiment has also been carried out in order to investigate the effects of mineralogical composition of saprolitic ores to their dissolution behavior and the leaching rates of metal with the implication for hydrometallurgical processing. Petrological and geochemical analyses indicate that peridotite at Soroako is a fragment of ophiolite containing predominantly olivine which rich in nickel. This is the most suitable protolith for the formation of higher grade Ni ores. Serpentinization of such peridotites has caused the remobilization of elements resulting in slight depletion of Ni as shown in Petea bedrocks. Relatively higher Ni content of the ore from west block than those ore from Petea block is a consequence of the difference in bulk Ni content of the parent rocks. Mineralogical studies indicate that chemical weathering of peridotite in the west block containing the original primary minerals (olivines, minor pyroxenes, and spinels) have resulted in the transformation of such minerals into secondary phases such as goethite, quartz, serpentine, talc and neoformed �garnierite� to form saprolite horizons