PETROGENESIS STUDY OF BAUXITE AND SCANDIUM MINERALIZATION IN TAYAN AREA, WEST KALIMANTAN

• Main Author: Sunjaya, Dedi
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/64477
• Institution: Institut Teknologi Bandung

Scandium (Sc) metal is presently required for modern industry, such as for military and defence, sports equipment manufactory and 4.0 technological basis for electronic devices. The high demand for Sc metal for the industry is leading to the increasing price of the Sc metal, from $ 1.500 to $ 2.500 / kg. However, Indonesia has not been able to take advantage of the economic opportunities for the Sc potency. This situation might occur since there are no Sc resources data, despite a few preliminary investigations about the Scandium potency in supergene deposits having been performed for nickel laterite and bauxite. Initial investigation for the presence of Sc in the bauxite mining sites of PT Antam Tbk, in the Tayan area, West Kalimantan, showed that Sc in various types of bauxite ranges from 13.7 to 52.9 ppm. Bauxite ore which contains 20-50 ppm of Sc is considered a resource and suitable to be exploited. Sc metal can be extracted from alumina processing residues or red mud, with Sc content ranging from 80 – 110 ppm. According to this information, a study on the Sc mineralization was carried out based on the petrogenic characteristics of the bauxite type in the Tayan area. Therefore, the Sc exploration becomes more directed, effective, efficient and contributes to the reporting of Sc resources in Indonesia. This study consists of four stages, i.e. literature review, data collection, data analysis and report compilation. This study aims to determine the presence of Sc based on bauxite characteristics, analyze the relationship of the presence of Sc relative to the enrichment of SiO2, Al2O3, Fe2O3 and TiO2 in bauxite and determine the exploration target for Sc based on bauxite characteristics in Tayan. The analytical method includes petrographic and X-Ray Diffraction (XRD) analyses. The geochemical method consists of X-Ray Fluorescence (XRF) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The petrogenesis of bauxite was performed based on petrography, XRF and XRD analyses. The results showed that bauxite in PT Antam Tbk, Tayan, derived from four different source rocks, such as pyroxene diorite, diorite, quartz diorite and granodiorite. Bauxite from pyroxene diorite has the characteristics of 10,71-14,39%, Al2O3 38,96-41,39%, and Fe2O3 23,03-23,41%. Bauxite from diorite is characterized by SiO2 10,03-11,53%, Al2O3 45,11-45,76%, and Fe2O3 16,33-17,27%. Bauxite from quartz diorite exhibits SiO2 20,95-25,18%, Al2O3 39,48-41,65%, and Fe2O3 13,67-14,31%. Bauxite from granodiorite contains SiO2 33,04-42,09%, Al2O3 31,98-36,43%, and Fe2O3 8,39-9,80%. Meanwhile, the mineralization of Sc was obtained from the ICP-MS analysis performed for bauxite ore- derived from four different parent rocks. Petrogenesis study of bauxite and Sc mineralization in Tayan area suggests that Sc content in pyroxene diorite parent rock is 15.10 ppm, Sc in bauxite is enriched 3 times, ranging from 42.60 to 53.30 ppm. The Sc content in diorite parent rock is 11.10 ppm, while Sc in bauxite ore is enriched about 3-4 times which contains 33.10-44.30 ppm. The Sc content in quart diorite parent rock is 6.90 ppm, Sc in bauxite has been enriched 3 times, from 21.90 to 25.10 ppm. The Sc content in granodiorite is the least with only 5.30 ppm and the Sc enriched in bauxite ore is about 2-3 times and ranges from 13.20-14.10 ppm. This study concludes that Tayan bauxite is derived from four types of parent rocks, i.e. pyroxene diorite, diorite, quartz diorite and granodiorite. The presence of Sc in bauxite is enriched for approximately 3 times higher than the existing Sc content in their parent rocks. The existence of Sc corresponds to the increase of Al2O3 and Fe2O3, but trends inversely to SiO2. The bauxite type in Tayan is lateritic, thus, Sc exploration can be carried out parallel to bauxite exploration. In order to have an effective and efficient Sc exploration in bauxite, it is recommended to explore rocks which contain abundant Al2O3 and Fe2O3, particularly in pyroxene diorite and diorite. Meanwhile, bauxite with high content of SiO2, such as in quartz diorite and granodiorite should not be prioritized in the Sc exploration.