Polymetallic Nodules Resource Estimation in the Suoi Thau-Sang Than Area, northeastern Vietnam

1,720 chemical, mineral, and petrography samples in the Suoi Thau-Sang Than area, northeastern Vietnam were collected to investigate polymetallic nodules resource. The similarity-analogy in ore geology, direct calculation method for metallization parameters, and mineral resource estimation based on cutoff grade change methods are employed to estimate polymetallic nodules resource from the Suoi Thau, Sang Than, and Ban Kep areas in northeastern Vietnam. The similarity-analogy in ore geology indicates 1,785,000 tons Cu, 12,005,000 tons Pb+Zn, and 195 kg Au in total. The direct calculation method for metallization parameters shows 2,060,000 tons Cu, 13,648,000 tons Pb+Zn, and 224 kg Au in total. These methods display that the Sang Than area contains mainly polymetallic nodules in the studied area. Following the mineral resource estimation based on cutoff grade changes, estimation results indicate potential Pb-Zn nodules resource in the Ban Kep and Cu nodules resource in the Sang Than, while no potential Au nodules resource in the Suoi Thau and the Sang Than as well as the Ban Kep. The estimation results obtained from mineral resource estimation based on cutoff grade changes are suitable with the results from the traditional geometric block methods. Our study suggests that the Sang Than area can be considered as a potential Cu nodules resource, and the Ban Kep area is potential Pb-Zn nodules resource in northeastern Vietnam for future exploitation, while there is no potential polymetallic nodules resource in the Suoi Thau area. Furthermore, the one resource estimation based on cutoff grade changes method displays an overview of the prospect on polymetallic nodules resources, indicating that this method can serve as a basis for the proposed selection of the prospective areas for effective Cu, Pb-Zn, and Au mineral exploration in the Suoi Thau-Sang Than area, northeastern Vietnam.

Effect of Cutoff Grade and Stripping Ratio on the Net Present Value for Hamama Gold Project, Eastern Desert, Egypt

This paper represents an attempt to examine the effects of Cutoff Grade (COG) and Stripping Ratio (SR) on the Net Present Value (NPV) for the proposed gold mine in Hamama area, hence to attain best operating condition corresponding to the optimum COG and SR in the proposed gold mine. Discount Cash Flow (DCF) model has been established to calculate NPV by taking the change in the COG and SR into account. This detects the effects of COG and SR on the NPV of this project. The actual production and cost data of Sukari Gold Mine (SGM) of Egypt have been taken as an indicator in creating DCF for the proposed gold mine where maximum NPV results proved the optimum COG and SR.

DELINEATION OF ORE OCCURRENCES IN ORE RESERVES APPRAISAL WITH MICROMINE PACKAGE

The ore quality requirements include: cutoff grade, minimum thickness of ore body, maximum permissible thickness of interbeds of barren rocks or offgrade ore within the ore body perimeter, minimum metropercent (metrogram) calculated as the product of cutoff grade and minimum ore body thickness. Recently, mineral reserves appraisal has put in practice automation within specialized programs of geological–surveying data processing. The principal subject in automation of ore occurrence delineation in Micromine package and the topic of this article is delimitation of an ore body across its thickness using the data from the ore quality requirements. This becomes necessary when geological data on external boundaries are absent, which is typical of variable morphology ore bodies: mineralized dikes and zones, ore folds, skarns, ore chimneys, etc. Previously, before this study, Micromine package implemented appraisal of composite material reserves in the following scenarios: along boreholes, by benches, by intervals, by geology, by content. The programmers implemented ,since version 16,the ore occurrence algorithm based on the ore quality requirements using a method in a separate menu tab: Drillhole/ Compositing/ Grade (GKZ).The main kinds (parameters) of the ore occurrence algorithm are the Strictly rules and the Relaxed rules.. The article describes general framework of the analysis of ordinary ore occurrences, and similarity and distinctions in performance of the main kinds of the algorithm. Technically, the ore reserves appraisal based on the ore quality requirements should use the algorithm where all the requirements are maximum possible taken into account. In Micromine package, such algorithm is the Strictly Rules with the option “Do not allow contiguous composites”. Practically, there arises multivariate coupling and delimitation of ore bodies in the identified ore occurrences. The article gives a few somewhat formalized examples to illustrate appropriateness of one or the other method of ore occurrence delineation. Automation of ore reserves appraisal results in essential acceleration of data processing. The described algorithms enable calculation and statistical processing of numerous alternatives of ore occurrences based on the input variables of the ore quality requirements: Cб, Mп, Mр, MC within a short time provided that the data are prepared and clean.

PERHITUNGAN SUMBERDAYA DAN CADANGAN LIMESTONE DENGAN METODE NEAREST NEIGHBOUR POINT DAN INVERSE DISTANCE SQUARE

Kegiatan eksplorasi endapan limestone di lokasi penelitian berupa pemboran eksplorasi full coring menghasilkan 16 titik bor. Kegiatan ini bertujuan untuk melihat jumlah dan distribusi CaO dan MgO sebagai gambaran perencanaan suplai bahan baku untuk keperluan produksi pabrik.Pemodelan blok pada endapan ini berukuran 25 x 25 x 10 meter menghasilkan 1351 blok dengan luasan area 49 Ha. Berdasarkan analisa bivariate CaO dan MgO didapatkan korelasi yang lemah dan negatif. Estimasi yang dilakukan untuk penentuan kadar adalah metode Nearest Neighbour Point (NNP) dan Inverse distance square (IDS)Perhitungan sumberdaya menggunakan metode NNP didapat sumberdaya terukur sebesar 34.950.000 Ton dengan kandungan kadar CaO Kurang dari 40% sebesar 3.572.000 ton, CaO 40% - 50% sebesar 5.323.000 ton, CaO lebih dari 50% sebesar 26.055.000 ton. Sumberdaya terukur dengan kandungan kadar MgO 1% - 5% sebesar 32.737.500 ton, Lebih dari 5% sebesar 2.212.500 ton. Berdasarkan perhitungan sumberdaya menggunakan metode IDS didapat sumberdaya terukur sebesar 34.950.000 Ton dengan kandungan kadar CaO kurang dari 40% sebesar 381.250 ton, CaO 40% - 50% sebesar 6.293.750 ton, CaO lebih dari 50% sebesar 28.275.000 ton. Sumberdaya terukur dengan kandungan kadar MgO 1% - 5% sebesar 34.950.000 ton dan Lebih dari 5% tidak ada. Berdasarkan nilai cutoff grade kadar CaO >50% dan MgO <5% hasil perhitungan menggunakan metode NNP yaitu didapat cadangan limestone sebesar 26.055.000 ton dan hasil perhitungan menggunakan metode IDS didapatkan cadangan limestone sebesar 28.275.000 ton. Kata Kunci : Limestone, Nearest Neighbour Point, Inverse Distance Square, Sumberdaya terukur, Cutoff grade.