COMPARATIVE ANALYSIS OF BLAST GEOMETRY EFFECTS ON FRAGMENTATION, PRODUCTION, AND BLASTING COST IN ANDESITE MINING AT PT. SULENCO WIBAWA PERKASA

Abstract

Suboptimal blasting is often the primary cause of failing to achieve production targets and escalating operational costs in quarry mining. This study aims to provide recommendations for blasting geometry and optimal cost estimates to achieve <40 cm fragmentation of 85% and support the production target of 50,000 bcm/year at PT. Sulenco Wibawa Perkasa, West Kalimantan. The research employed a quantitative approach using a comparative method, comparing three blasting geometry designs (R.L. Ash, C.J. Konya, ICI-Explosives) against actual field geometries from five blasting events conducted during July–August 2024. Fragmentation predictions were performed using the Kuz-Ram model. The results showed that the actual geometry had a powder factor of 0.89 kg/m³, significantly above the normal range for andesite (0.4–0.6 kg/m³). The proposed ICI-Explosives Design 2 proved to be the most optimal, yielding fragmentation of 85.19% passing <40 cm (meeting the 85% target), a production volume of 2,488 bcm per blast (exceeding the 2,100 bcm target), and a powder factor of 0.54 kg/m³ (39% more efficient than the actual operation). The cost per bcm for this design was Rp38,080, representing a 38% reduction compared to the actual cost (Rp61,567/bcm). The study concludes with a recommendation for the ICI-Explosives Design 2 geometry comprising: 6 m borehole depth, 2.4 m burden, 2.4 m spacing, 0.6 m subdrilling, 5.4 m bench height, 1.6 m stemming, 4.4 m charge column length, and 80 blast holes per shot, at a cost of Rp94,740,215 per blast or Rp1,184,253 per blasthole