تحلیل احتمالاتی ارزش اقتصادی بلوک استخراجی در معادن روباز با در نظر گرفتن تأثیر عدم قطعیت قیمت ماده معدنی و هزینه‌های عملیاتی

نوع مقاله : مقاله پژوهشی

نویسندگان

گروه مهندسی معدن، دانشگاه صنعتی همدان

10.29252/anm.7.13.15

چکیده

داده‌های ورودی در فرآیند بهینه‌سازی محدوده نهایی پیت روباز، مجموعه‌ای از بلوک‌ها است که هر یک از آن‌ها دارای یک ارزش اقتصادی خالص بوده وطراح با انتخاب بلوک‌های مناسب از میان بلوک‌های ذکرشده اقدام به بهینه‌سازی طراحی و بیشینه‌سازی ارزش خالص معدنکاری می‌نماید. ارزش خالص اقتصادی تخصیص داده‌شده به هر بلوک با استفاده از اطلاعاتی چون قیمت ماده معدنی، هزینه‌های عملیاتی، هزینه‌های ذوب وپالایش وهزینه‌های فرآوری و غیره محاسبه می‌گردد. روند تغییرات قیمت فلزات و همچنین هزینه‌های معدنکاری در سال‌های مختلف نشان می‌دهد که قطعی فرض کردن این پارامترها موجب بروز خطا در روند محاسبه ارزش اقتصادی بلوک‌های معدنی می‌شود. در روش‌های معمول برای محاسبه ارزش اقتصادی بلوک، همواره تأکید بر ثابت فرض کردن پارامترهایی چون عیار، هزینه‌های عملیاتی، قیمت ماده معدنی و ... بوده است. این در حالی است که عدم قطعیت پارامترهایی چون قیمت کاملاً بدیهی بوده و ثابت فرض کردن آن‌ها منجر به بروز خطا در فرآیند محاسبه ارزش اقتصادی بلوک می‌شود. در تحقیق حاضر سعی شده است که ابتدا به بررسی نقش عدم قطعیت اقتصادی پرداخته‌شده و سپس با استفاده از روش شبیه‌سازی مونت‌کارلو ارزش اقتصادی بلوک با در نظر گرفتن عدم قطعیت‌های قیمت ماده معدنی و هزینه‌های عملیاتی محاسبه شود. برای نیل به این هدف از داده‌های اقتصادی معدن مس گرسبرگ اندونزی استفاده شده است. نتایج این تحقیق نشان داد که روش شبیه‌سازی مونت‌کارلو توانایی بالایی در تخمین عدم قطعیت‌های اقتصادی پروژه‌های معدنی داشته و ارزش اقتصادی بلوک محاسبه شده از این روش با خطای کمتری نسبت به سایر روش‌ها به مقدار واقعی نزدیک‌تر است. همچنین ملاحظه شد که ارزش فعلی خالص به دست آمده از روش مونت‌کارلو از روش‌های معمول بیشتر بوده و به واقعیت نزدیک‌تر است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

The Probabilistic Analysis of Block Economic Value (BEV) in Open-Pit Mines Considering the Effect of Uncertainties in Metal Price and Operational Costs

نویسندگان [English]

  • Masoud Zare Naghadehi
  • Hesam Dehghani
  • Roya Naderipour
Dept. of Mining, Hamedan University of Technology (HUT), Iran
چکیده [English]

Summary
In this research, the Block Economic Value (BEV) and project NPV in an open-pit mine has been analyzed probabilistically by using the Monte Carlo Simulation (MCS) method to deal with the uncertainties in the nature of the most important economic parameters including metal price and operational costs. The results showed that the outcomes are closer to the reality by this method compared to the results of the classic methods.
 
Introduction
The basic input in the process of open-pit limit optimization is a set of block values representing the net economic worth of each block. Based on the estimated block economic values (BEV’s), the optimizer selects the optimum destination of each block in order to maximize the overall pit value under some given technical constraints. A dollar value is usually assigned to each block by estimating the revenue of recoverable metal at a given fixed metal price and subtracting applicable mining, processing and other costs. The variation trend of metals price and mining costs over the years shows that deterministic assumptions for values of such parameters will result in errors in the process of BEV calculation. The effective parameters such as metal price, operating costs, grade etc. are always assumed deterministic in the conventional methods of BEV calculation. While, these parameters have, obviously, uncertain nature.
 
Methodology and Approaches
In this paper, the BEV and project NPV were initially determined using Whittle’s formula based on deterministic economic parameters. Then the Monte Carlo Simulation (MCS) method was employed and the economic uncertainties such as the metal price and cost uncertainties were taken into account. The economic data of Grassberg Copper Mine were utilized to achieve this goal.
 
Results and Conclusions
The results showed that the Monte Carlo simulation method is highly capable of estimation of economic uncertainties. The estimated block economic values using this method are closer to the actual values compared to other methods and the error percentage is lower. As well, it was observed that the net present values obtained by the Monte Carlo simulation are closer to the reality compared to the other calculations.

کلیدواژه‌ها [English]

  • Economic Uncertainty
  • Block Economic Value
  • Net Present Value
  • Monte Carlo simulation
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