APPLICATION OF MORPHOGEOCHEMICAL DOMAINS AND EFFICIENCY FUNCTION IN BAUXITE EXPLORATION PLANNING: A CASE STUDY OF PT. MEGA CITRA UTAMA, WEST KALIMANTAN, INDONESIA

• Main Author: Debrian Mahantara, Rizal
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/87118
• Institution: Institut Teknologi Bandung

The increasing demand for high-quality bauxite to support Smelter Grade Alumina (SGA) production at Mempawah highlights the importance of effective exploration strategies. Bauxite grade with Al?O? content exceeding 42% and TSiO? below 19% is critical for efficient smelting processes. PT. Mega Citra Utama, a major bauxite supplier in West Kalimantan, currently holds 33.58 million tons of washed bauxite (WBX) resources with an average Al?O? content of 43.17% and TSiO? of 22.46% as of December 2023. However, the relatively high silica content in existing resources requires additional exploration to identify additional bauxite deposits to comply with the required specifications and ensure long-term supply stability. This study focuses on optimizing exploration planning at PT. Mega Citra Utama using two key approaches: morphogeochemical analysis and the efficiency function. Morphogeochemical analysis is employed to identify high-potential areas by dividing the region into domains based on regolith distribution, while the efficiency function determines the optimal spacing of drill holes by balancing exploration costs and success probabilities, thereby enabling cost-effective and efficient planning. Primary data utilized in this study include LIDAR survey results covering 10,000 hectares with a resolution of 2 meters and data from 6,462 drill holes totaling 41,664.1 meters in depth. Secondary data consist of exploration cost records from 2008 to 2013, encompassing both direct and indirect expenses, such as measurements, drilling, laboratory analysis, permits, and security. These cost data were adjusted to 2024 values, incorporating a 4% annual inflation rate. The morphogeochemical analysis identified four domains (A, B, C, and D) in the study area. Among these, Domain A are the best area for exploration, due to its superior bauxite quality, with an Al?O? content of 45.5% and TSiO? of 20%. This domain is located in the central to northern parts of the study area. The efficiency function further determined that a drill hole spacing of 75 meters is optimal achieving an exploration cost of IDR 5.15 million per hectare and a success probability of 24.34%. The study ultimately identified two target exploration blocks. The detailed block, spanning 627.67 hectares, is projected to yield 2.22 million tons of WBX with an exploration cost of IDR 3.23 billion. Meanwhile, the regional block, covering 621.91 hectares, is expected to produce 2.03 million tons of WBX at an exploration cost of IDR 2.65 billion. Combined, these blocks are estimated to generate 4.26 million tons of WBX, with a per-ton exploration cost of USD 0.09.