Evaluasi Kesesuaian Perhitungan Cadangan Secara Manual Terhadap Penggalian Nyata Bijih Timah Blok Realisasi Pada BWD Kundur 1 PT Timah Tbk Di Laut Penganak Bangka Barat

Evaluation of the Conformity of Manually Reserved Calculations on Real Excavation of Tin Ore of Realized Blocks at BWD Kundur 1 PT Timah Tbk In the Sea of West Bangka Penganak

Abstract

BWD Kundur 1 with the ability to dig up to 60 meters below sea level . Tin Mining Processes in the
Sea Penganak is mined using Bucket Wheel Dredge in the realization block with a total production of
30 tons in September 2018. With the production target the calculation of company reserves is greater
than the production realization of the BWD. The problem obtained in the field is a mismatch of reserve
calculations with the realization of extracting tin ore that exceeds the tolerance limit. For good yield
coefficients, namely 1 - 1.2, which has been set SOP. The reserve calculation uses the manual
method using the Area of Influence method which this calculation is done by making a polygon area of
the influence of the borehole and calculating the area of influence of the drill hole manually with 3 drill
holes in the realization block of Kundur 1 BWD of 34,348 tons and the results of the realization of the
2018 septber month were 30 tons. After obtaining the results of the two reserve calculations and the
results of the realization, then the two results can be compared to determine the Results Coefficient,
find the factors that caused the incompatibility of the calculation of the performance such as BWD
performance, the type of layer extracted BWD, weather at the time of excavation and efforts to
improve Results Coefficients such as doing selective mining to determine the productive direction of
multiplication. From the results of the manual calculation of the realization block obtained Pdh 34,3
tons while the results of realization in the Psb field of 30 tons, the percentage difference in the ratio is -
12,65% and the Results Coefficient of 0.85 including inappropriate from KH 1.2 according to SOP with
0.2 tolerance.