Improvement and Acceleration of Rebuild and Conversion Process for ore Wagon at Grasberg Block Cave Mine PT Freeport Indonesia

Abstract

The transition to wet muck-dominated production at PT Freeport Indonesia’s Grasberg Block Cave mine requires reliable conversion of dry-model ore wagons into wet-model units; however, delays in transportation and workshop activities have constrained production output. This study aimed to identify the root causes of inefficiencies across the Underground–Highland–Lowland logistics route and the rebuild station, as well as to formulate measures capable of sustaining a conversion rate of two wagons per week. A mixed-method approach was employed, combining field observations, project progress records, and a focus group discussion involving five stakeholder representatives. Fishbone analysis was used to examine logistics-related delays, while the Current Reality Tree was applied to identify workshop bottlenecks. Eleven alternatives were evaluated using Kepner–Tregoe Decision Analysis and Potential Problem Analysis. The findings revealed several constraints, including limited lowboy availability, access queues, coordination gaps, restricted workshop space, shared labor resources, wheelset queues, unsuitable tools, inaccurate rubber component dimensions, and paint damage risks. The use of Flat Rack Container transportation, exclusion of wheelsets from the main rebuild quotation, and separate quotations for decoupler fabrication emerged as priority short-term solutions. Five cumulative capacity improvement levers were projected to reduce the average cycle time from 23.84 to 14–15 days per wagon and increase sustainable output from approximately 2.5 to eight wagons per month. These measures provide a roadmap for meeting conversion demand before wet muck becomes the dominant production condition.