Major risk factors for mining project development
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(1) Natural factors: mainly refers to geological resource conditions and external construction conditions;
(2) Process technology factors: mainly refers to the mining process, methods and equipment;
(3) Market factors: mainly refers to the price and cost of mineral products, including: auxiliary production materials, energy, equipment, exploration (mining) mining rights fees, land acquisition, labor and other expenses;
(4) Management factors: mainly refers to the management level of mining (plant) mode, production, safety, technology, quality, operation, etc.;
(5) Soft environmental factors: mainly refers to financing conditions, fiscal and taxation systems, relevant regulations, standards and changes.
Among the above five factors, the (1) and (2) factors are the most sensitive and most critical to mining projects. While the other three factors are also important, they are similar to other industrial projects. Therefore, this paper only analyzes and expounds the factors (1) and (2).
I. Naturally explain the risk analysis of mining project development
(1) Geological resource conditions
Geological resources are the object of mine project development, and it is the foundation of the success of mine project development. This is also the most fundamental reason why the development risk of some mine projects is far greater than any other project development.
Because geological resources are buried deep underground, although it has been obtained through a series of scientific methods, means and procedures through scientific geological exploration process; however, the reliability and accuracy of its resources and quality are firstly investigated by different explorations. The degree of exploration and accuracy of the stage (pre-examination, census, detailed investigation, exploration); in addition, affected by different types of mineral exploration types (I, II, III) and ore body occurrence characteristics of different mineral deposits; The important influence of responsibility, integrity and so on. It is precisely because of the above identified and uncertain natural and human factors that the risk of geological resources is inherent and cannot be circumvented, but only countermeasures can be reduced. Therefore, the original National Reserve Committee of China has established the allowable values ​​for the risk of mineral deposit exploration: A level ± 20%, B level ± 30%, C level ± 45%. Different types of deposits (such as: iron deposit, zinc deposit of copper and lead, tungsten and molybdenum deposit, white gold silver deposit, etc.), different exploration methods, means and the like are different exploration teams inevitable allowable value or exceeds the specification And to determine the risk of exploration error. To further illustrate the specific risk characteristics of geological resources, three of the main sub-factors are described as follows:
1. Risk impact of changes in geological resources
The geological resources of the deposit, especially the industrial reserves that have been proved and controlled and can be used as the basis for mine construction (equivalent to the old standard “A+B+C†level), determine the production scale and corresponding service life of the mine construction and calculate the amount of mining infrastructure projects. (Open-pit mining infrastructure stripping, pit mining development, mining and cutting engineering), infrastructure investment and infrastructure time only basis. If the reserves, especially the initial production reserves, are greatly reduced, the original mine production scale will be too large, the mines will be unable to put into production, reach production, the service life and product output will decrease, resulting in high or large capital investment and production. The increase in costs, the decline in output value and profits, the increase in the repayment period of infrastructure loans, the increase in infrastructure interest, etc., will seriously cause enterprises to lose money for a long time. This phenomenon is not uncommon in the development of mining projects:
The last century, 60 to 70 years, in bauxite construction in China, due to the exploration of the ore body shape and difficult to control network resources, often due to the discontinuous ore body (especially the emergence of karst deposits), resulting in a significant reduction in the actual amount of ore, Not only has the volume of mine infrastructure construction increased, but the production time of the investment has been lengthened, and the scale of the mine has been reduced.
In the 1970s, an open-pit copper mine in China was also reduced by the amount of upper mines, which increased the amount of infrastructure stripping by several million cubic meters. The investment was greatly increased, and the mine could not reach production, which directly affected the investment effect of the mine and made the initial stage of production. The benefits are not good. In the 50s and 60s of the last century in China, the “three-sided†mining model of “side exploration, design, and construction†was once popular. Since the resource reserves were not clarified, the design scale was too large, and the mine could not be invested for a long time. (Da) production, resulting in huge waste of state investment. To this end, after summing up this lesson, the state has banned it to prevent such blind construction of mines. Foreign exploration requirements are very strict and standardized, and the purpose is to reduce this most basic development risk.
Through detailed technical and economic evaluation and financial analysis of different scale schemes, the inherently closely related relationship between the above-mentioned geological resources and scale, infrastructure projects and investment, product output, output value, cost and benefit can be comprehensively and systematically reflected.
2. Risk impact of ore quality changes
Ore quality includes: ore type, ore grade, ore nature useful and harmful components of ore, optional ore. When the ore quality deteriorates, it is not as obvious and direct as the risk impact caused by the reduction of the above-mentioned geological reserves. But it also has a very serious negative impact on economic efficiency:
Dexing Copper Mine is a paper-grade large porphyry copper deposit. Its main product is copper concentrate. During the period of low price of mineral products before the mid-1990s, its copper concentrate products can only protect the capital, and the mine profit is Obtained from gold, silver and molybdenum as by-products in copper concentrate. If the deposit is a single copper ore with elements and elements, the adverse consequences of the development of the mine are obvious. The exploration geological silver grade of a silver mine in Jiangxi (500t/d) is about 193g/t, but the actual average geological grade after mining exposure is only 90~110g/t, which makes the mine lose money after it was put into production in the early 1990s. The price of silver rose from 500,000 yuan / t to 100 ~ 1.1 million yuan / t before turning losses into profit. Of Some Tantalum and niobium ore (1500t / d) in tantalum and niobium concentrate production value and cost nearly flat for the first 90 years of production of the last century, but on the tantalum and niobium was too fine tailings - feldspar profit, if the iron is too high feldspar The price has dropped drastically, and the quality of the products and the profitability of the company have been guaranteed through the beneficiation of iron ore . The silver grade of a silver polymetallic ore (300t/d) in Jiangsu is greater than 300g/t, and the “lead+zinc†grade is 18%-20%. It is equivalent to a silver grade 150g / t, capacity 600t / d single silver mine, plus a "lead + zinc" grade 6% to 8%, capacity of 900t / d lead-zinc mine production and efficiency. However, if the above-mentioned 1 silver mine and 1 lead-zinc mine are built alone, the investment and cost will increase by more than 2 times, and the benefits are far less than the benefits of this 300t/d silver polymetallic mine.
3. Risk impact of changes in development technology conditions
The development technical conditions mainly refer to the characteristics of ore body occurrence (mine body shape, thickness, dip angle, strike length, burial depth, etc.), ore properties (type, structure, structure, grain size, beneficial components, mud, etc.) The physical and mechanical properties of the ore (hardness, stable solidity, etc.), the hydrogeology of the mining area, rivers and lakes, construction and construction, etc. The above-mentioned mine development technical conditions must be mastered through the geological exploration of the deposit. It is to judge the difficulty of deposit development (especially mining) and special requirements for safety (such as: mining safety prevention caused by structural fracture zone in the deposit, surface and groundwater prevention, high sulfur mine fire prevention, deep well rockburst, geothermal The only risk factor for this).
Different mineral deposit development technical conditions will directly affect a series of major technical and economic solutions in mining development, such as mining methods, development methods, mining methods, water prevention, mineral processing, production capacity and equipment level. For example, when the ore body is buried shallow and thick, and the overlying rock (soil) layer is not thick, it is advantageous to adopt high-efficiency, low-cost, large-scale open-pit mining. The proportion of ore produced by open-pit mining of non-ferrous metals in the world is 91% for aluminum mines, 90% for copper mines and 45% for nickel mines. Although the number of open-pit mines in China only accounts for 11%, the output accounts for 47%. As far as underground mining is concerned, the development method of Pingshuo is very suitable for the burial elevation of the ore body at the local erosion reference level due to the small amount of development of the tunnel, the investment, the transportation, ventilation and drainage methods are simple, safe and low in production cost. Above the deposit. On the contrary, the burial target of the ore body must use the wellbore with large volume, high investment, complicated transportation, transportation, ventilation and drainage, and relatively poor safety and high production cost (shaft, slant) Development methods for wells, slopes, etc.) The deep well development (depth of 800~1000m) mine has higher technical requirements for mine lifting, filling, ventilation (including geothermal), drainage, rock burst, etc., and the corresponding investment and cost also increase. In summary, it can be seen that only the condition of the buried depth of the ore body has such a critical impact on the mining method and the decision-making method of the mine development. For example, a mine with a small depth of burial is not high in quality, and the options are also general. In addition, there are large water bodies and important roads to be protected on the surface. When using open field mining method, the post-mortar stone filling treatment When the goaf is used, the economic benefits of the mine are acceptable, and the decision can be developed. However, because the open field treatment measures of the above mining method are difficult to ensure the safety of surface rivers and roads, it is necessary to use the method of mining with the detachment filling method. The cost is high, the ore value is low, and the mine development is in a state of no profit, which ultimately makes the mine difficult to decide on development. This example reflects the contradiction between technical safety requirements and economically reasonable requirements.
In summary, it can be seen that the geological resource conditions have a very prominent and very sensitive impact on the development of mining projects, especially the selection of mining schemes and beneficiation processes, and are often the key factors that are difficult to reverse. Therefore, in the early stage of development of the mine project, we must use the geological resources seriously and cautiously, and must not be too hasty. Otherwise, "the speed will not be reached," or even the "blood will not return."
(2) The external construction conditions for the development of the mine project mainly refer to the traffic conditions for the contact between the mining area and the outside; the power supply and water supply conditions necessary for the production and living of the mining area; and the flat earthwork for the construction of various industrial facilities and administrative and living facilities in the mining area. engineering. That is known as the "three links and one leveling" project. However, with the requirements of the global economic sustainable development strategy, the environmental protection and soil and water conservation conditions of mine development have been listed as the main content of external construction conditions, and even more stringent. For example, before the design of the above three external construction conditions, the state requires the preliminary environmental assessment and soil and water conservation evaluation work. Only after these two evaluations are passed can the transportation, water and electricity design work and engineering construction be started, and the environmental engineering and soil and water conservation engineering construction should be “three simultaneousâ€.
Since mine projects are usually in a mountainous environment with varying degrees of difference, the ease of external construction conditions and the corresponding risk impacts are also very different. According to the rough statistical analysis of the investment in the development of mine projects at home and abroad, it can be seen that the investment in external construction conditions accounts for about 25% to 40% of the total investment of the project, especially in the areas of economically underdeveloped mountains and regions with stricter environmental protection and soil and water conservation requirements. It will even be higher. It is this restriction of high investment ratio that makes many large non-ferrous metal mines in western China difficult to obtain development and utilization as soon as possible before the 21st century. Although external construction conditions do not pose a potentially huge risk to project investment as well as geological resource conditions; however, since it is an advanced investment directly serving resource development, this investment risk coexists with geological resource risks, and generally Risk factors that are difficult to reverse. In particular, the investment in traffic conditions is even more so because of the wide range of issues involved. It must be pointed out that: in China's "three links" construction, there may often be problems of co-construction and sharing with the local government. In particular, China may also attach the requirements for local economic revitalization. Once the local interests are handled properly, resources will inevitably arise. Sharing disputes over ownership, and creating risks that affect mine construction and normal production.
It can be seen that the external construction conditions are difficult to reverse due to the large proportion of investment, so it is also a fairly important and important risk factor in the development of mine projects. Don't take it lightly.
Second, process technology and equipment factors for the risk analysis of mine project development
The technical factors of the mine project mainly refer to the mining, mineral processing technology and equipment level for the process technology. In terms of the technical factors of the mining process, it has the following two distinctive features:
First, the application scope and effects of the mining process technology and equipment are firstly subject to the development technical conditions in the ground-holding resources;
Secondly, according to the characteristics of geological resources, the optimal combination of mining technology and equipment can transform unfavorable geological resources within a certain range and to a certain extent, to achieve the purpose of mitigating the risk of geological resources, fully demonstrating scientific and technological progress and technological innovation. Great role.
Therefore, there is a very close relationship between the mining process technology and the geological resources. A brief analysis is as follows:
As mentioned above, different development technical conditions determine different mining methods, development methods, mining methods and ventilation systems and methods, mineral processing technology, equipment level, production capacity and so on.
Different ore types have different beneficiation processes and methods. For example, tungsten ore (tin) ore is mainly re-elected, various sulfide minerals such as copper ore are mainly flotation, iron ore is mainly magnetically selected, etc.; complex polymetallic deposits require a joint beneficiation process. Due to the different structure and structure of the same mineral, the complexity of the mineral processing process and the product indicators obtained are also different. There are even a lot of geological resources that are due to the poor quality of their ore, which makes the sorting process complicated, the index is poor, and economically unprofitable. The list is too numerous to mention.
The dip angle, thickness and grade of different ore bodies play a leading role in the selection of mining methods. For example, if the rock is broken, but the grade is high, in order to ensure the safety of mining and recover resources as much as possible, it is advisable to adopt a cementation filling method with high recovery rate and safe production; the ore is not stable, the deposit is large, the grade is not high, and the surface is allowed to fall. It is advisable to adopt a stage mining method with large production capacity (such as: VCR method) or segmentation and stage caving method; if the ore is stable, the ore body is below medium thickness, and the inclination angle is slow, the comprehensive method or room column method in the empty field method should be adopted. Wait. The use of each mining method should be achieved by matching the appropriate equipment levels.
For example, a Jinchuan high grade copper-nickel, platinum group element-rich large deposits, but broken ore, unstable, selection cemented filling method (scale 3000t / d) at the time of makeup of underground mining, and due to the filler material The equipment is not closed, the filling quality is not high, and the production capacity cannot be achieved. Later, the introduction of foreign advanced technology, especially equipment (scraper, filling equipment, etc.), using mechanized (trackless equipment) panel down approach The cement filling method greatly improved the production capacity and provided technical and equipment guarantee for the second phase expansion to 8000t/d. Its process technology and major economic indicators have reached the international advanced level (for example, the production capacity of the mining area reached 817t/d). From this mine example, it is explained that the optimized combination of mining technology and equipment can overcome the unfavorable conditions of crushing and unstable rock, and the production capacity is increasing and the efficiency is continuously improved. At the same time, the high value of the mine's high-grade ore and by-products gives the mine economic strength to adopt the above-mentioned high-cost mining methods.
Another example is that Dexing Copper Mine is a very large porphyry copper mine. When using medium-sized mining equipment, it can only reach a production capacity of 30,000 t/d. It can not fully utilize the advantages of abundant reserves and overcome the disadvantages of low grade. After switching to large-scale foreign mining equipment, the production capacity has been expanded to 90,000 t/d, thus giving full play to the advantages of scale benefits, overcoming the disadvantages of low grades, and significantly improving the economic benefits of enterprises.
In the early 1990s, the Zijinshan gold mine has been regarded as a medium-sized (4tAu metal), low grade (1.3g/t), thin ore body, thick layer of cover, and pit mining and dew. Mining methods are not economical. After the design, the geological theory first breaks through the frame of the traditional double-index ore body, and adopts the single-index heavy-duty ore body, so that the reserves will jump above 80tAu metal, the grade is 0.75g/t, and the ore body shape becomes thicker. It is very suitable for large-scale open-pit mining, plus the high degree of oxidation of ore and excellent leaching characteristics. The smelting process adopts the cyanide spray leaching technology which is simple in process and low in cost at the time. The “mine mine†has changed into the largest open-pit gold mine with the largest economic benefits (the mining capacity of 30,000 t/d). This is a typical example of the selection of design concepts, optimization of process technology, and mitigation of risk factors for geological resources. China's bauxite is mainly a water-type bauxite ore, which belongs to high-aluminum, high-silicon, low-iron, low-aluminum-to-silicon ratio, poorly soluble ore. The ore processing process is complex, the process is long, alkali consumption and energy consumption. High and high production costs. After scientific and technological research, the beneficiation process and the Bayer process were successfully combined to create a new process for the production of alumina by the “mineralization-Bayer processâ€, so that the one-water bauxite ore was desiliconized by beneficiation and changed from medium to low grade ore. High-grade ore-rich, the ratio of aluminum to silicon increased from 5 to 6 to more than 10, which significantly reduced the energy consumption and production cost of alumina production, and the economic benefits were considerable, which enabled China's abundant first-water bauxite to be well utilized. Optimize the combination sorting process, change the disadvantages as the advantage, fully transform and utilize the geological resources, and realize the pioneering work of the circular economy of bauxite mining.
Fankou aluminum-zinc mine and Xinqiao pyrite mine are large underground mining mines with complicated hydrogeological conditions (Note: Xinqiao Mine is pit exposed and mining mountain). In order to prevent groundwater and surface water, it has effectively adopted effective sparse Various comprehensive water control measures combined with plugging enable the mine to develop as early as possible and maintain long-term stable production, and obtain better economic benefits. This is an example of optimizing the combined mining water technology to change the technical conditions of the hydrogeological conditions unfavorable and to resolve this risk factor.
These examples show the enormous role of technological advancement and innovation. In summary, it can be seen that the practical, reliable and especially the innovative combination of process technology and equipment factors is an effective way to resolve the risk of natural factors in mine project development.
Third, the conclusion
(1) The development of mining projects has inherent natural risks that are unique to geological resources and that cannot be circumvented and can only be reduced. This risk is caused by many uncertain factors in the quantity and quality of the geological resources and the reliability of the resources, and thus has a prominent impact on the technical economy of project development;
(II) Development of mining projects Through the implementation and innovation of man-made technical factors such as mining technology and equipment, it is still possible to recover geological resources in an adequate, effective and economic manner. This is the process, method and fruit of human beings to specifically reduce the risk of mining project development.