** Availability of iron ore is the model for the study of the availability of mineral resources services. The so-called mineral resource availability study is a research report on the dynamic quantitative analysis of the supply capacity of important mineral reserves around the world and the preparation of mineral availability analysis under the current and future market price changes. Simply put, the feasibility study reports for individual deposits are assembled and their availability is determined based on market prices. Then the availability analysis model is a set of mathematical expressions that calculate the available quantity based on the market price. **

** I. Current status of research on the availability of mineral resources at home and abroad **

** The research on the availability of foreign mineral resources is typical of the Mineral Availability System (MAs) of the market economy countries built by the former US Bureau of Mining in the 1970s and 1980s. The system is not a simple database system, but a system engineering. It is a decision support system that integrates basic data collection and sorting, information statistical database system and data evaluation and analysis system. The process of completing the availability system analysis is divided into three parts: deposit verification and selection, data collection and data utilization. In terms of economic evaluation, it is the economic feasibility analysis of each deposit to determine the quantity of minerals that can be economically obtained from the deposit at the recoverable cost (presumed mineral price) under the specified un-expired investment profit rate. . The cost indicators for investment, mining, mineral processing , and smelting based on the availability analysis are estimated by logarithmic equations rather than directly using actual cost data. The reason for this is to exclude the impact of management and management factors on the cost of specific mines on costs, so that the cost is comparable; second, the actual cost is difficult to obtain for unused deposits. **

** In the focus of Canada, metal economic team since 1988 has annually published a strategic research report, which relates to the availability of mineral research mainly copper, nickel, cobalt, lead, zinc, gold, silver, platinum group and diamonds, Analyze the important mineral deposits newly discovered in the past 20 years. It uses the market price changes in the past 10 years as a parameter to estimate mine operating costs. These reports became an important complement to the world's mineral availability analysis system after the availability of US availability system data was discontinued. **

** The domestic availability study began in the 1980s. After three demonstrations, it initially grasped the â€œhomeâ€ of China's mineral resources and played an important role in the decision-making of national mineral resources. These three rounds of argumentation are mainly based on qualitative or semi-quantitative economic evaluation methods. **

** In some scholars' exploration of the available methods, the early research basically uses the reserve static for the protection period, and the later research tends to study the reserve dynamic availability. For the dynamic study of the availability of mineral resources, the resource allocation is usually based on the predicted metal demand of each year or period (such as 5 or 10 years) according to the ratio of production to storage, and the reserves required for each period are predicted. Other scholars study the interaction between these factors by compiling the relationship model between mineral reserves, grades and costs, and prices, and characterize the changes in prices and costs that affect the changes in mineral mining grades and reserves. In addition, in the mining development project, it is a very important task to carry out technical and economic evaluation of the deposit and find the expected cost of mineral products. If some scholars believe that the development cost of mineral resources ultimately comes down to the cost of mineral products, under the premise of optimal management and technical level, the expected cost of mineral products is related to the specific conditions of mineral resources, so they are not According to the resource status, indicators such as fixed asset investment, operating cost, and management cost are calculated to calculate the cost of mineral products. Instead, the specific cost of the mineral product is directly estimated according to different resource conditions, and then the method is calculated by a method such as BP neural network. Product Cost. **

** Second, the idea of â€‹â€‹the feasibility model construction **

** Establish an iron ore availability model by using a set of parameters to express whether an iron ore deposit is economically recoverable. To measure the economic recoverability of an iron ore deposit, the core is to compare the income and cost of the iron ore mine after development. Under the premise of considering the time value of the currency, if the income is greater than the cost, it is available (economically available) Mining), otherwise it is not available (not economically recoverable). Thus, the iron ore availability model is the difference between the sales revenue per unit of iron ore and the cost of unit iron ore. Considering that the iron ore market is mainly the iron concentrate market, it turns to the difference between the iron concentrate sales revenue and the iron concentrate cost. Therefore, the key to the problem is to establish a sales revenue model and a cost model, especially to establish a cost model for unit iron concentrate. **

** Generally speaking, when calculating the mining operation cost, different methods can be adopted, such as analog cost method, detailed design cost method, and statistical analysis method. The analogy cost method is also an analog cost method. The cost estimate is based on the analysis of other similar business activities. At the same time, some adjustments are made if necessary, and finally the cost estimate of the project is made. The detailed design cost method means that the cost is sufficient. On the basis of investigation, analysis and technical determination, according to the technical level that the enterprise has now reached, the cost of producing certain products under effective operating conditions determined by the enterprise; the statistical method is based on the statistics of a large amount of data. The functional relationship between cost and related parameters is summarized. **

** Third, the construction method of the availability model **

** The current methods for establishing an availability model include a static evaluation method and a dynamic evaluation method. Among them, the static evaluation method commonly uses the following indicators: total profit amount, investment profit rate, static investment return rate and static recovery investment period. Dynamic evaluation methods include total present value method (Pv method), net present value method (NI method), net present value ratio method (NPVR method), internal rate of return method (IRR note and dynamic investment payback period method. Dynamic evaluation below) The net value method in the law is constructed. **

** The net present value method is a dynamic method widely used in Western countries: the evaluation method. The so-called net present value (NetPresentValue) is to calculate the cash receipts and payments for a certain year according to the established discount rate (generally the expected return rate of the project, or the industry rate of return, loan interest rate, capital cost, etc.) The present value formula or the present value coefficient table is converted into the initial amount of the project, and is added or subtracted according to the nature of payment, which is the net present value of the current year. **

** The specific financial model is: **

** Where: NPV is the net present value, CI is the cash flow person, CO is the gold outflow,: is the discount rate, i is the year serial number, and n is the calculation period. **

** When the net present value calculation is carried out, during the construction period, the net cash flow is negative because the mining enterprise has no sales income; in the trial production period, the output has not yet reached the design production capacity, and the mining enterprise can only obtain one point of sales income. In most cases, this part of the sales revenue is fully compensated for the cash outflow of the year, and the negative net cash flow continues to exist only when the sales income is greater than the operating cost of the current year, the increase in sales private funds and liquidity. A positive net cash flow occurs in the normal production period, the output has reached the designed production capacity, no longer pays for construction investment, only operating costs and taxes, which is generally a positive net cash flow. **

** Fourth, the construction process of the availability model **

** 1. Build parameter model **

** The availability model is supported by several indicator parameters, so the parameter model must be established first. For specific model parameters, there are some differences at home and abroad. Cash flows in foreign financial models include: capital expenditures, increase or decrease in earnings, production and maintenance costs, profit and loss value, loan principal, interest expenses, liquidity, opportunity costs, recurring expenses, etc., excluding accounting periods. Accounting concepts involving currency flows, such as depreciation, accruals, book losses, and expenditures and income incurred before the project. The main elements of China's financial model include: mineral resource reserves, production scale, mine service life, fixed asset investment, production cost or manufacturing cost, total cost, operating cost, mining recovery rate, ore depletion rate, ore recovery rate, Mineral product sales income, loan interest, taxes, etc. In view of the data situation, in order to construct the model, the relevant parameters in the iron ore availability model can be appropriately simplified, considering only the recoverable reserves, the sales of mineral products, the service life of the mine, the cost of iron mining, the cost of mineral processing, and the investment in fixed assets. Etc., where iron mining costs, ore dressing costs include operating costs and taxes, while Giants are considered available in mining hills. **

** 2. Build a net present value model and calculate the lowest available price **

** After each parameter model is established, the various parameters are aggregated and the total availability analysis net present value model is derived. It can be constructed by distinguishing between two different situations, that is, the available model of open and underground iron ore and the available model for distinguishing between open and underground. In this way, the lowest available price can be obtained from the net present value model, that is, the price at which the net present value is zero. **

** 3. Construct a price-reserve curve **

** Since each mine corresponds to a minimum price, the lowest price of all open pit mines and underground mines is calculated according to the formula, and then these prices are sorted from high to low, and one price corresponds to the reserve R of the corresponding mine. . As shown in Table 1, the price is sorted from small to large, and the mine reserves corresponding to the lowest available price of each mine are filled in the corresponding positions, and then the accumulated available reserves corresponding to the price are calculated, so that the lowest available price is used. For the abscissa, the cumulative available reserves are plotted on the ordinate, and a two-dimensional scatter plot of the price-reserve is made. Use the excel software or other related software to smooth the scatter and make a price-reserve curve. **

** V. Thinking about further improving the availability analysis model **

** The credibility of the model lies in the reliability and completeness of the sample data. Among all the parameters, the mining cost and the beneficiation cost are calculated according to the sample. Since the cost is inferred from some natural properties of the mine, the correctness and comprehensiveness of a mine's representation is related to the degree of cost model simulation. In the actual operation, we use the repository database data, and the data integrity of the database is not ideal, and some data items lack more data, so the completeness of the basic database restricts the accuracy and universality of the availability model. Sex. Therefore, strengthening the construction of the basic database is particularly important. **

** The verification of the model is also a very important part. How to verify, mainly to see the parameters are unreasonable, the method science is not scientific. In the iron ore availability model, if it is a known mine under construction, if the NPV value of the net present value is calculated to be less than zero at the current price, it is obvious that the model is problematic and the model needs to be Correction, check the parameter selection is unreasonable, the sample data is reliable, and so on, so that the NPV is greater than zero. Only after a lot of debugging can the model be close to the actual situation, and finally the model will be put into use. Of course, for a known production mine, the first thing to understand is its true financial performance, which is currently difficult to achieve. **

** The grade of iron ore is also a problem to be considered in future models. If the grade is not taken into account in the model construction, or if there is only one grade in a mine, once the market price is lower than the minimum available price, all reserves of the mine are not available, and there is a certain gap with the actual situation. So what is the ideal situation? It is necessary to know what the reserves of different grades are and what the cost is, that is, to understand the relationship between the grade-reserve and the cost. If a mine's reserves are given, it corresponds to a grade, and a grade corresponds to a cost. The lowest price of the reserve can be calculated, or a mine has a price-reserve curve, which will price-reserve curves of all mines. After accumulating, the price-reserve curve of the national iron ore mine is obtained. **

** In short, in the construction of iron ore availability models, from qualitative to semi-quantitative to quantitative, the general principles and directions are still moving toward the perfection and accuracy of quantification. **

** references **

** [1] The "Guide to the Evaluation of Mining Rights" is compiled by the team. Mining rights assessment guide. Beijing: China Land Publishing House, December 2002 **

** [2] China Institute of Certified Public Accountants compiled financial cost management. Beijing: Economic Science Press, April 2007 **

** [3] Zhao Zhiyong, Zhang Zhili, Li Yongli. The BP neural network based on MATLAB calculates the cost of iron ore products. Journal of Hebei Institute of Technology, Vol. 25, No. 4, November 2003 **

** [4] China Metallurgical and Mining Enterprise Association Key Metallurgical Mine Statistics Annual Report, October 2006 **

** [5] Zhang Qinli, Wang Xinmin, Liu Baowei. Mineral Resources Assessment. Changsha: Central South University Press, July 2007 **

** [6] Chen Jianhong, written by Zhan Desheng. Mining economics. Changsha: Central South University Press, August 2007 **

** [7] Li Wanheng, Fu Mingwei, Yang Changming. Mineral economy and management. Wuhan: China University of Geosciences Press, 2000 **

** [8] Li Xiangyi, Li Zhongxue. Mining Economics 1 Beijing: Metallurgical Industry Press, 2006 **

** [9] Beijing Jingwei Assets Appraisal Co., Ltd. edited. Mining rights assessment. Beijing: China Land Publishing House, 2007 **

** [10] Rudowski Chemical Economics - Natural Resources Development and Management Wuhan: China University of Geosciences Press, 1991 **

** [11] Cui Shuangping. Neural network control model for the quality of Jianshan iron ore concentrate. Metal Mine, No.11, 1998, Issue 269 **

** [12] Wang Lijie, Tao Shuren. Research on Mineral Resource Valuation Model Xuzhou: China University of Mining and Technology Press, December 1994, Vol. 23, No. 4 **

** [13] Zheng Wenyuan. A Method of Dynamic Analysis of Mineral Resources Availability: A Discussion on the Relationship between Reserve Grade and Cost Price and Its Model Compilation. Geology and Exploration, 2006-04 **

** [14] He Xianjie, Cao Xinyuan. American mineral availability system. China Geology, No. 11 of 2000 **

** [15] Zhang Raspberry: American Mineral Resources Availability Analysis System and Working Principles Introduction China Mining, 2002, Vol.11, No.3 **

** [16] reminder first. Analysis and Thinking of Ways to Reduce Production Costs in Open-pit Iron Mines, Design and Construction of Metallurgical Mines, September 2001, Vol. 33, No. 5 **

** [17] Hu Qisheng, Zhu Zenghan The availability of iron ore resources in Hubei Province Resource Environment and Engineering, August 2006, Vol. 20, No. 4 [18] Zhang, Cao Xinyuan. Research on the availability of copper resources in China. China Mining, Vol. 12, No. 2, 2003 **

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