Triswan Suseno

This research aims to analyze the resilience of Indonesia’s copper ore reserves in supporting sustainable copper cathode production targets, in line with national downstream policies. Using a quantitative approach, this study evaluates secondary data from national mineral reserve reports and the production capacity of major smelters. The analysis is conducted by calculating the reserve-to-production ratio to project mine life under three scenarios of increasing domestic refining capacity, including an aggressive scenario of 1.145 million tons per year. The results indicate that based on current reserves, the estimated mine life is approximately 21 years under maximum production capacity. However, with potential resource-to-reserve conversion of approximately 4.318 billion tons and accounting for ore grade decline, the life of Indonesia’s copper ore reserves is projected to extend until 2077. The study also reveals a structural gap, where 70% of cathode production is still export-oriented due to low domestic manufacturing absorption. The uniqueness of this paper lies in the integration of geological reserve aspects with the dynamics of downstream policies and industrial structure theories. Practically, this study provides important implications for the government in formulating strategic reserve management and emphasizes the urgency of integrating upstream smelting with downstream manufacturing to ensure long-term industrial sovereignty.

Intense chemical weathering in tropical environments poses challenges for conventional geochemical exploration, as primary lithological signatures become heavily altered. Stream sediment geochemistry provides a robust alternative for detecting anomalous geochemical patterns under these conditions. In this study, 636 stream sediment samples and 15 rock samples were evaluated using Principal Component Analysis (PCA), Median + 2 Median Absolute Deviation (MAD), and Concentration–Area (C–A) fractal modeling to identify potential anomaly zones. These results were compared with the traditional Mean plus 2 Standard Deviation (SD) approach. The findings indicated that Mean + 2SD offers a conservative threshold but overlooks anomalies in heterogeneous datasets, while Median + 2MAD provides robustness against outliers. The C-A fractal model effectively characterizes low- and high-order anomalies by capturing multiscale variability. Elements such as Au–Ag–Hg–Se–Sb–As form a system indicating low- to intermediate-sulphated epithermal mineralization. Au–Pb points to polymetallic hydrothermal mineralization along intrusive contacts. The southern region is a primary mineralization center controlled by an intrusive–volcanic boundary, whereas the east and west areas exhibit secondary mineralization, characterized by altered lava breccia. The correlation between shallow epithermal and deeper intrusive-related porphyry systems, especially regarding Au–Ag, offers new insights into the metallogenic landscape of the Sunda–Banda arc. Beyond regional significance, this research presents a geostatistical workflow designed to mitigate exploration uncertainty in geochemically complex zones, providing a structured approach applicable to volcanic-arc mineralized provinces worldwide.

Most nickel laterite smelting to produce ferronickel is carried out by using an AC-arc furnace. Although the DC-arc furnace is advantageous in smelting fine ore, it is rarely used for nickel laterite. In this work, the effect of slag basicity and stoichiometry of reductant addition in the smelting of low-grade saprolitic nickel ore on nickel grade and recovery, yield, and phases of slag have been investigated clearly. The smelting process was conducted in a laboratory DC-arc furnace with a 30 cm diameter of a single electrode. A 5 kg low-grade saprolitic nickel ore (1.92 Ni-12.97 Fe), some coke as reductant, and some limestone as fluxes were smelted in a DC-arc furnace for about an hour. The pouring temperature of hot metal and slag was 1400-1500°C. The 0.8 of quaternary slag basicity and 0.8 of stoichiometric carbon of reductant resulted in the optimum smelting process of nickel ore in a DC-arc furnace producing ferronickel containing 14.59% Ni grade with 92.26% recovery.

Starting in 2022, the State-owned coal company in South Sumatera plans to produce coal 5.72 million tonnes per year. 3.43 million tons of which will be processed to produce 450,000 tons of polypropylene, 1.47 million tons to produce 400,000 tons of dymethyl ether, and 811,885 tons to produce 570,000 tons of urea fertilizer. The amount of coal to steam power plant needs as much as 3.45 million tons, bringing the total addition of coal production per year as much as 9.17 million tons.The coal downstreaming sector will able to absorb labour of 1,604 people, the size of the value of money which will be obtained by these workers is estimated at USD 26,459,273, an the company's profit from the results of the processing of the coal downstreaming of USD 298,476,000. The existence of the industry turned out taxes, generating government revenue to USD 110.819.765. Using input output method, the increase in coal production amounted to 9.1 million tonnes or IDR 3.44 trillion worth encourages other sectors to improve the output of Rp. 3.62 trillion. The impact of investment for processing coal in Muara Enim in 2022 results on increasing of MuaraEnim GDP to IDR 114,38 trillion and creating jobs for the various sectors as much as 5,578 people.Keywords: GDP, coal, downstream, input, output.