INTAN Jurnal Penelitian Tambang

STABILITY OF OPEN MINE SLOPE USING THE LIMIT EQUILIBRIUM METHOD AND RISK ANALYSIS TO SUPPORT MINING INFRASTRUCTURE PLANNING

Irianto, Mapuay Menasye Theo Afasedanya — Tue, 28 Oct 2025 00:00:00 +0000

Slope stability is a critical aspect in open-pit mining operations, particularly in limestone (C Group Mining) quarries that are widely developed in the Polimak area, Jayapura City. This study aims to evaluate slope stability under various slope geometries and hydrogeological conditions, as well as to establish a relevant risk map to support the design of safe and sustainable slopes. The methodology involved field surveys to collect slope geometry data and soil-rock samples, followed by laboratory testing to determine key geotechnical parameters (cohesion, internal friction angle, unit weight, and UCS). Slope stability analysis was performed using the Limit Equilibrium approach with Slide2 software, considering different combinations of slope heights (10–20 m), angles (45°–65°), and drainage conditions (dry vs. saturated). The results indicate that increasing slope height and angle significantly reduces the Factor of Safety (FoS), while rising groundwater levels due to rainfall can further decrease FoS by up to 20%. For instance, a 20 m high slope at 65° under saturated conditions yielded an FoS of only 0.73, far below the minimum safety threshold (FoS ≥1.3). Based on the risk matrix, such conditions fall into the high to extreme risk categories. This study recommends implementing multi-bench slopes with a maximum angle of 45°, complemented by proper drainage systems to maintain stability. The findings are expected to serve as practical guidance for managing limestone quarry operations in Polimak to ensure safe and efficient mining activities.

APPROACH FOR ESTIMATING COHESION AND ANGLE OF INTERNAL FRICTION USING UNIAXIAL COMPRESSIVE AND TENSILE STRENGTH VALUES OF ROCKS

Sari Melati, Romla Noor Hakim, Santoso Santoso, Muhammad Zaini Arief — Tue, 28 Oct 2025 00:00:00 +0000

Rock characteristics, such as failure criteria, play a critical role in the assessment of stability in rock engineering, alongside design factors. Stability in rock engineering is cohesion (c) and friction angle (j) are parameters of failure criteria obtained by performing direct shear test or triaxial test. However, the measurements require a certain number of intact rock samples. On the restricted condition or preliminary study, an approach involves for predicting both parameters. Using data statistical analysis of Uniaxial Compressive Strength (s_c) and Brazilian Tensile Strength (s_t) of limestone and gypsum, empirical equations to predict c dan j were resulted in this research. Cohesion is strongly determined by s_t with average constants in equations: c = 1.81s_t dan c = 1.84s_t, for limestone and gypsum. Cohesion of limestone depends on s_c with average constant in equation: c = 0.22s_c. Friction angle and rock strength ratio (s_c/s_t) are related by exponential equations: c/s_t = 2.1624e^0.0314^jdan s_c/s_t = 3.6936e^0.0183^j, for limestone and gypsum, respectively. This approach using constructed empirical equations provides the prediction of c and j that relevant with theoretical values, indicated by 2.8% and 8.22% relative deviations. These empirical equations are useful for predicting the values of c and j.

A MINERALOGY AND CHLORITE CHEMISTRY CONSTRAINTS ON THE FORMATION CONDITION OF PROPYLITIC ALTERATION IN THE TUJUH BUKIT PORPHYRY DEPOSIT, EAST JAVA, INDONESIA

Fri, 31 Oct 2025 00:00:00 +0000

Propylitic alteration develops chlorite, epidote, and calcite assemblages commonly found in porphyry copper–gold deposits. This study aims to understand the formation temperature, oxygen, and sulfur fugacity of chlorite, a characteristic central element of propylitic-related minerals such as epidote and calcite, using a combination of qualitative and quantitative experimental methods. The propylitic alteration forming condition was analyzed in detail using a superprobe (JXA-iSP100) and Electron Probe Micro Analysis (EPMA) at a voltage of 15.0 kV. The chlorite composition is relatively homogeneous, and displayed as Mg-rich chlorite (Type-I) within Al^IV-Mg-Fe, ripidolite with respect to Si vs Fe/(Fe+Mg). The chlorite geothermometer indicates that the crystallizing temperature ranges from 288.30 to 332.82°C. The oxygen and sulfur fugacity log fO2 and log fS2 of chlorite are low ranges (– 70.4 to – 51.85) and (– 32.55 to – 20.65), respectively. The analyses identify the mineral as true epidote, with spatial variations indicating Fe occurs as Fe³⁺ and Mn as Mn²⁺. However, the examined proportion of moles of the significant elements (Mg, Ca, Fe, Mn) indicates that calcite is present in hydrothermal systems.

GLOBAL GOLD PRICE VOLATILITY AND ITS CORRELATION TO RESOURCE AND RESERVE DYNAMICS AT PT MERDEKA COPPER GOLD TBK

Utari Retno Sulistyo Rini, Fanteri Aji Dharma Suparno, Siti Aminah, Haeruddin — Mon, 03 Nov 2025 00:00:00 +0000

Gold (Au) commonly occurs as nuggets or grains in rock veins and alluvial deposits. Because of its scarcity, chemical stability, and distinctive properties, gold commands higher market prices than base metals. Global gold price volatility has a significant impact on the strategic decisions of mining companies. This study aims to quantify the correlation between international gold price fluctuations and the dynamics of gold resources and reserves at PT Merdeka Copper Gold Tbk. Using a quantitative approach, the average gold prices and the company's annually reported resource and reserve figures were analyzed. The Pearson correlation coefficient was employed to measure the strength and direction of the relationship. The results reveal a robust and statistically significant negative correlation. This inverse relationship suggests that periods of high price volatility are associated with a decrease in the company's reported gold resources and reserves. The findings highlight the significant impact of external market dynamics on resource management. It is recommended that stakeholders incorporate market volatility forecasts into long-term strategic planning and resource valuation models to enhance resilience.

DESIGN OF PIT X BASED ON PRODUCTION TARGETS USING MINE SCHEDULING CONCEPT AT PT Y

Sat, 15 Nov 2025 00:00:00 +0000

Pit design in surface mining requires a systematic approach that considers operational capacity and efficiency to ensure optimal production target achievement. In the actual condition of the second quarter of 2025, pit X design at PT Y was carried out manually using a trial-and-error method. This method was time-consuming and less flexible to parameter changes, and caused significant deviations from production targets, with overburden reaching 110%, coal only 89%, and stripping ratio increasing to 4.19 from the target of 3.39. This study aims to develop pit design based on Mine Scheduling Concept using SPRY Scheduler software to improve operational effectiveness and efficiency. An applied quantitative method was implemented by integrating reserve data from Minescape, heavy equipment parameters including availability, utilisation, and hourly rate, as well as a mining calendar aligned with operational conditions in the third quarter of 2025. The results show that the generated pit design achieves production targets with very high accuracy: overburden of 4,093,991 Bcm with a deviation of -0.02%, coal of 1,206,663 MT with a deviation of 0.00%, and a stripping ratio of 3.39 as targeted. The application of SPRY Scheduler produces measurable, accurate, and adaptive pit designs without trial-and-error processes, supporting efficient and sustainable mine planning.

PREDICTION OF SETTLEMENT AND LAND USE CHANGES ON MANSINAM ISLAND FROM 2025 TO 2031 USING THE CELLULAR AUTOMATA SIMULATION METHOD

Mon, 24 Nov 2025 00:00:00 +0000

Indonesia, as an archipelagic country, faces development challenges on its small islands, including Mansinam Island. This study aims to predict settlement and land cover changes on Mansinam Island for the period 2025–2031. The data used were surface reflectance-corrected Sentinel-2 imagery with a spatial resolution of 10 meters. The imagery was acquired in 2019, 2022, and 2025. Land cover classification was performed using a supervised classification method with the minimum distance algorithm, achieving an accuracy of 87.82%. Land change prediction modeling was carried out through land use change analysis and simulation using the Cellular Automata (CA) and Artificial Neural Network-Cellular Automata (ANN-CA) models. The model produced a Percent of Correctness of 89.96%. The simulation results indicate that from 2025 to 2031 there will be no significant land change, with transformed land areas of 43.85 ha in 2025, 42.62 ha in 2028, and 42.64 ha in 2031. The results also show that the development rate on Mansinam Island tends to slow down.

GEOGRAPHIC INFORMATION SYSTEM (GIS) APPLICATION FOR MAPPING INFRASTRUCTURE AND TOURISM POTENTIAL IN MANSINAM VILLAGE

Mon, 01 Dec 2025 00:00:00 +0000

This study aims to provide accurate spatial data to support ecotourism planning in Mansinam Village through the application of a Geographic Information System (GIS). Field data acquisition was conducted using a handheld GPS to record the coordinates of infrastructure and tourist attractions. The data was then processed in ArcGIS software through the stages of georeferencing, digitization, overlay analysis, and thematic map creation. This follows spatial mapping standards commonly used in geological mapping and spatial analysis activities in the mining sector. This study produced two thematic maps: a Settlement Map and a Map of Tourist Attraction Locations in Mansinam Village. Both maps provide spatial information on settlement locations, accessibility levels, and the distribution of natural, cultural, religious, and historical tourist attractions. The spatial analysis demonstrates the relationship between accessibility and tourism development potential, while also identifying locations requiring infrastructure improvements. In addition to contributing to tourism planning, the mapping process used also demonstrates methodological alignment with geological mapping and spatial analysis practices commonly used in the mining sector. The findings of this study are expected to provide an empirical basis for local governments and stakeholders in formulating more targeted and sustainable regional development strategies.