Analisis Deviasi Kadar Ni dan Fe Material Saprolite antara Block Model dan Hasil Sampling Temporary Ore Stockpile terhadap Potensi Ore Loss dan Dilusi
DOI:
https://doi.org/10.29313/bcsme.v6i2.24253Keywords:
Block Model, Deviasi Kadar, Dilusi, Match Factor, Ore Loss, Saprolite, Temporary Ore StokpileAbstract
Abstract. PT Sinar Terang Mandiri Tbk is a laterite nickel mining company that uses a block model as a basis for mine planning. Differences in nickel (Ni) and iron (Fe) grades of saprolite material are found between block-model predictions and temporary ore stockpile (TOS) sampling results. These deviations may indicate discrepancies that potentially cause ore loss and dilution. This study aims to determine Ni and Fe grade deviations, ore recovery, match factor values for Ni, Fe, and mass, and the factors causing grade and mass deviations. A comparative quantitative descriptive method was applied by comparing block-model predictions with TOS results. The data consisted of cut-off grade parameters, block-model grades and mass, TOS assay grades, and TOS mass. The analysis covered three domes: TF.A.8407, TF.A.8410, and TF.A.8413. The results show that TF.A.8407 had Ni and Fe deviations of +0.20% and +3.23%, with ore recovery of 35.3% and potential ore loss of 64.7%. TF.A.8410 had Ni and Fe deviations of -0.06% and +7.16%, with ore recovery of 32.4% and potential ore loss of 67.6%. TF.A.8413 had Ni and Fe deviations of +0.43% and +4.57%, with ore recovery of 34.2% and potential ore loss of 65.8%. The deviations were influenced by sampling, selective mining, variations in saprolite material, excavation boundaries, and equipment cleanliness.
Abstrak. PT Sinar Terang Mandiri Tbk merupakan perusahaan pertambangan nikel laterit yang menggunakan block model sebagai dasar perencanaan penambangan. Pada kegiatan penambangan ditemukan perbedaan kadar nikel (Ni) dan besi (Fe) material saprolite antara hasil prediksi block model dan hasil sampling temporary ore stockpile (TOS). Deviasi tersebut dapat menjadi indikasi ketidaksesuaian yang berpotensi menimbulkan ore loss dan dilusi. Penelitian ini bertujuan mengetahui deviasi kadar Ni dan Fe, nilai ore recovery, match factor kadar Ni, kadar Fe, dan massa, serta faktor penyebab deviasi kadar dan massa. Metode penelitian yang digunakan adalah deskriptif kuantitatif komparatif dengan membandingkan hasil prediksi block model dan hasil TOS. Data yang digunakan meliputi parameter cut-off grade, kadar dan massa block model, kadar hasil assay TOS, serta massa hasil TOS. Analisis dilakukan pada dome TF.A.8407, TF.A.8410, dan TF.A.8413. Hasil penelitian menunjukkan bahwa TF.A.8407 memiliki deviasi Ni +0,20% dan Fe +3,23%, ore recovery 35,3%, serta potensi ore loss 64,7%. TF.A.8410 memiliki deviasi Ni -0,06% dan Fe +7,16%, ore recovery 32,4%, serta potensi ore loss 67,6%. TF.A.8413 memiliki deviasi Ni +0,43% dan Fe +4,57%, ore recovery 34,2%, serta potensi ore loss 65,8%. Deviasi dipengaruhi oleh pengambilan sampel, selective mining, variasi material saprolite, batas penggalian, dan kebersihan alat.
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