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Abstract. Coal is a sedimentary rock (solid) that can burn, comes from plants, and is brown to black in color, which since its deposition is exposed to physical and chemical processes that make it rich in carbon content. PT Alamjaya Bara Pratama is a company in the coal mining sector with the mining method used is open mining (Surface Mining). The quality of coal is a basic factor in decision making by the Buyer. The quality of coal produced during the production process needs to be measured in relation to the storage or hoarding of coal, as well as the factors that affect changes in the value of coal quality. The purpose of this research is to know the Stockpile management system; know the value of coal quality in Stockpile (ROA) and in Barging (COA); analyze changes in the value of coal quality using the Shewhart control chart; as well as knowing the permitted time limit for stockpiling or storing coal in the Stockpile. The method used in this research is, data collection with literature study techniques, field observations, and secondary data collection. Then do data processing by way of frequency distribution and data interpolation. Finally, data analysis uses the Shewhart control chart to determine the quality of the coal. Based on the results of research and data analysis, it is known that the Stockpile management system in the research area is coal stored in ROM (Raw of Material) separated based on sulfur and caloric value, then a process of size reduction is carried out, and then in Blending, then stored in Stockpile as Coal Coal Product that is ready for shipment. The average quality of coal obtained in Stockpile (ROA), TM = 28.17%, Ash = 5.6%, Total Sulfur = 0.39% and the calorific value = 4537 Kcal / Kg, and in Barging (COA), TM = 28.12%, Ash = 5.37%, Total Sulfur = 0.38% and the caloric value = 4564 Kcal / Kg. Based on the analysis of changes in coal quality using the Shewhart control chart, it is found that changes in coal quality are still within the Warning Limit tolerance limits and based on the coal specifications requested by the Buyer are still accepted. There is an effect of the length of stockpiling at the Stockpile on the quality of coal, where the maximum time (t) of stockpiling is 6 days before arriving at the Warning Limit.Keywords: Dumps, Slope Stability, Safety Factors, Groundwater.Keywords: Coal Quality, Stockpile Management, Shewhart control diagram.Abstrak. Batubara merupakan batuan sedimen (padatan) yang dapat terbakar, berasal dari tumbuhan, serta berwarna coklat sampai hitam, yang sejak pengendapannya terkena proses fisika dan kimia yang menjadikan kandungan karbonnya kaya. PT Alamjaya Bara Pratama adalah salah satu perusahaan di bidang pertambangan batubara dengan metode penambangan yang digunakan ialah tambang terbuka (Surface Mining). Kualitas batubara merupakan faktor dasar dalam pengambilan keputusan oleh pihak Pembeli (Buyer). Kualitas batubara yang dihasilkan selama proses produksi perlu dilakukan pengukurannya terkait dengan tempat penyimpanan atau penimbunan batubara, serta faktor-faktor yang berpengaruh terhadap perubahan nilai kualitas batubara. Adapun tujuan dari penelitian ini adalah untuk Mengetahui sistem manajemen Stockpile; mengetahui nilai kualitas batubara di Stockpile (ROA) dan di Barging (COA); menganalisis perubahan nilai kualitas batubara menggunakan diagram kontrol Shewhart; serta mengetahui batas waktu penimbunan atau penyimpanan batubara di Stockpile yang diperkenankan. Metoda yang digunakan dalam penelitian ini adalah, Pengumpulan Data dengan teknik studi literatur, observasi lapangan, dan pengumpulan data sekunder. Kemudian dilakukan Pengolahan Data dengan cara distribusi frekuensi dan penginterpolasian data. Terakhir Analisis Data menggunakan diagram kontrol Shewhart untuk mengetahui kualitas batubara. Berdasarkan hasil penelitian dan analisis data, diketahui bahwa Sistem manajemen Stockpile di daerah penelitian ialah batubara yang ditimbun di ROM (Raw of Material) dipisahkan berdasarkan nilai sulfur dan nilai kalori, kemudian dilakukan proses pengecilan ukuran, dan selanjutnya di Blending, kemudian disimpan di Stockpile sebagai batubara Coal Product yang telah siap untuk dikapalkan. Rata-rata kualitas batubara yang diperoleh di Stockpile (ROA), TM = 28,17%, Ash = 5,6%, Total Sulfur = 0,39% dan nilai kalori = 4537 Kcal/Kg, dan di Barging (COA), TM = 28,12%, Ash = 5,37%, Total Sulfur = 0,38% dan nilai kalori = 4564 Kcal/Kg. Berdasarkan analisa perubahan kualitas batubara dengan menggunakan diagram kontrol Shewhart diperoleh bahwa perubahan kualitas batubara masih dalam batas toleransi Warning Limit dan berdasarkan spesifikasi batubara yang diminta oleh Buyer masih diterima. Terdapat pengaruh lamanya penimbunan di Stockpile terhadap kualitas batubara, dimana diperoleh waktu (t) maksimal penimbunan adalah 6 hari sebelum sampai ke Warning LimitKata Kunci: Timbunan, Stabilitas Lereng, Faktor Keamanan, Muka Air Tanah.Kata Kunci : Kualitas Batubara, Manajemen Stockpile, Diagram kontrol Shewhart |
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