Ore grade (%) = amount in mining the amount of metal-containing (t) / ore the amount of (t) × 100%, where the actual volatility of this ore grade is normal, as long as no need to deliberately controlled within reasonable limits However, in practice, sometimes the fluctuation of the ore grade is too large, so that many technical and economic indicators affecting the normal production of the mine [1-2], resulting in failure to reach production, meet the standard, and ultimately can not complete the quantity and quality of the task. Therefore, this paper analyzes the main factors affecting the grade of ore for the specific situation of Nanhegou.
1 Overview of factors affecting the grade of Nanhegou mining
The mining method used in the current stage of Nanhegou is mainly a vertical deep hole falling mine with a sub-column sublevel caving method, and the auxiliary is a shallow hole retaining method. The loss and depletion of ore in the mine production process directly determines the level of the ore grade [3], which is the decisive factor and key factor affecting the fluctuation of the grade of the ore. Caving mining uses overburden mining, which is a direct factor leading to ore loss and depletion, and an important factor affecting the fluctuation of the ore grade. Therefore, the influencing factors can be explored from the specific processes of the mining process [4-6].
From an objective point of view, the mineralization of the mining area is extremely uneven, or the ore body has irregularity and other unexpected factors (because the mining production process has great randomness and uncertainty). Sexuality and unpredictability, etc.; when the caving method is used to mine ore, the selected ore-mining plan, and the planned production and release operation schedule, it is impossible to fully grasp due to too many limiting factors.
From a subjective point of view, in the geological grade decoupling process, since the groove sampling is not implemented according to the standard, the geological grade is virtualized, resulting in the geological data being defective and incomplete, directly affecting the mining design work, and the resulting indirect relationship Far more than natural factors; the density of sample collection in the on-site geological cataloging work is not enough, resulting in large errors in the depletion and rich control limits of the stope, which can not accurately provide reliable geological data for the production designer, affecting the ore body during the mining design process. The overall grasp [7]; the quality of blasting deep holes and mining engineering is not relevant, affecting the mining managers can not grasp and control the mining process, resulting in increased loss of depletion in each mining route; The actual situation of the river ditch is planned or not, and the problems that have occurred during the implementation of the plan are not adjusted and compiled in a targeted manner. As a result, the control of the ore-mining personnel cannot be effectively and reasonably implemented, and the loss of ore loss is directly affected. Mine grade; the mine manager failed to communicate with the underground miners in a timely and effective manner. There is a fault in the feedback, which leads to the failure to achieve mining and separation during the mining process. Sometimes even the quantity is the only task, the ore waste rock is mixed out, the waste stone is used as the ore or the ore is used as the waste rock; the mine producer The lack of understanding of the company's concept, did not have a deep enough understanding of the quality of the mining to determine the benefits of the enterprise, resulting in the maximum expansion of the personal interests of underground workers, lack of initiative awareness; lack of production prospecting links, so that the ore geological grade continues to fluctuate, production designers can not go Designing the stope, resulting in on-site construction and design sometimes leaks, production construction and design are inconsistent, resulting in production chaos, unplanned engineering has occurred, of course, will also affect the mining manager's control of the stop.
2 The actual factors affecting the fluctuation of the ore grade
According to the technical and economic indicators of some stopes in Nanhegou (see Table 1) and the production and operation plan (see Table 2), the main factors affecting the fluctuation of the ore grade are explored.
It can be seen from Table 1 that the original geological grade and the collapse grade of the stope design are more or less different, because the caving mining is to mine under the condition of overburden, the ore loss and depletion are obvious, but two The reason for the excessive difference in grades is worth pondering. The above data is only the ideal index value calculated according to the regulations in the design. In the actual process, the mine mining loss rate and the depletion rate are much larger than this value (see Table 3).
Table 2 is the three important indicators for the treatment of ore, ore grade and ore recovery rate in Nanhegou. It can be mutually checked. For example, the ore recovery rate and the treated ore amount can be reversed to the original ore grade. Of course, it can be based on the calculation formula. The loss of ore and the depletion rate during the mining process, which is a closed chain relationship network [8-9]. Production and operation plan The ore grade is a very important economic indicator for mine operation. According to the regulations: the industrial index of the Hujiatun Nanhegou mining area requires a copper boundary grade of 0.3% and a minimum industrial grade of 0.5%.
At the present stage of Nanhegou, there is a lack of production prospecting, which has a great impact on the re-enclosure of the ore body. To some extent, there are many projects waste and mistakes. In addition, the Nanjiagou of Hujiatun lacks the mine management department, which is considered to be a major cause of large fluctuations in the grade of the ore, because the purpose of the mine management is to minimize losses and depletion, and to recover resources. It is produced underground. The last process, so its status is crucial. Secondly, the direct determinant of the difference in the grade of the ore, the miners, the miners in the underground are only for personal convenience and benefit, dumping the ore as waste rock or discharging the waste rock as ore. There are certain problems in mine management. Furthermore, geological site cataloging and slotting sampling are inaccurate, resulting in geological technicians making errors in the geological ore body boundary demarcation, causing a series of chain reactions, unreasonable design, etc., resulting in increased design loss and depletion, eventually resulting in mining quality. not ideal. Finally, the quality of the measurement work is another factor affecting the grade of the mine. Because the construction of the excavation, mining and mining works in the underground is not accurate, resulting in a large deviation between the site and the design. In the case of last resort, the design needs to be temporarily modified. So that each economic parameter indicator can not be carried out according to the optimal route.
3 measures
3.1 The importance of production prospecting
Production prospecting is the continuation of exploration geology. It is of great significance for the re-delineation of the ore body and the re-approval of reserves. The ore body is the prerequisite for the design of the mining designers. There is no precise ore body boundary, the mining designer The design intent can only be empty or have no reasonable mining design at all, and it has no practical value, which leads to unplanned engineering. It has inadvertently increased the amount of mining engineering, resulting in waste of mineral resources and increased mines. Additional economic investment, so production exploration is of great significance. In the mine operation process, it is always hoped to obtain the most amount of mine with the minimum investment. Although the project is encrypted during the production exploration process, the newly added ore is sometimes negative, which means that the amount of minerals is reduced. It is counterproductive, but at a deeper level, if you have a deep understanding of the ore body, this is very important for grasping the trend of mine economic activities. In addition, it is sometimes necessary to combine with the genetic rules of the deposit to enable mining designers to have a further understanding of the ore body space shape and grade grade [10-11].
3.2 Decisive of mining management
The sublevel caving method with bottom column is to mine the ore under the overburden, and to achieve balanced ore mining, which has great influence on the mining management and loss depletion.
As the intermediate link of mining and selection process, the mining management work plays an extremely important role in the production and operation of the mine. It can stabilize the beneficiation production and reduce the cost of mineral processing; reduce mining losses, recycle off-balance sheet ore and extend the service life of the mine; Improve the grade of raw ore and improve product quality [15].
Of course, the mining management work is also very high for the duties and technical requirements of a mining manager. It is required that all departments should ensure mutual coordination, and it is necessary to strengthen on-site management, the ore mining plan, the ore mining system and the determination of the ore plan. A lot of work needs to be done, so the talent reserve work for mining management should be started as soon as possible.
3.3 The need for education and rational management
The miners are the key to whether the ore grade is reasonable. The miners confuse the ore and waste rock, and the overall benefits of the enterprise are set aside for personal interests, which seriously damages the development of the mine economy. Therefore, it is necessary to educate the miners. Mine managers should strengthen communication with underground workers so that their intentions can be timely feedback and exchange, so that managers can make corresponding decisions. In addition, mining managers should strengthen the management of workers and increase The intensity of supervision, if necessary, should introduce corresponding reward and punishment policies, so that it can achieve underground civilized construction, no ash, no mixed hair, in order to improve the grade of mining.
3.4 Reliability of geological technical work
There is no standard grooved ditch in each prospecting tunnel under the Nanhegou well. The groove does not work according to the technical specifications of the grooved sampler, so that the geologist cannot accurately delineate the ore body, or the delimited ore body is not reliable. Sometimes the on-site observation is quite different from the actual test, so sometimes the second groove sampling will happen, causing unnecessary trouble and wasting time, energy and financial resources. If the ore body is inaccurate, the mining design error is very large, sometimes causing a lot of unnecessary engineering, and sometimes it will cause a lot of ore body resources to be wasted, which will cause the ore grade change. Therefore, you need to have a deeper understanding of your job responsibilities, otherwise you will lose the interests of the company.
3.5 Accuracy of measurement work
The measurement work is the advance force of the mine production, and it is in the position of the mining enterprises. The quality of each project in the mine underground is basically controlled by the measurement, but in the actual work, due to the new and old replacement, the insufficient measurement personnel and the unclear understanding of the duties of the current work, etc., the engineering difference is very large. The phenomenon of digging and the phenomenon of roadway snoring are endless, which sometimes necessitates to modify the mining design to make up for the mistakes in the measurement work. Sometimes the mining work cannot be carried out normally, and many ores cannot be produced, which affects the loss and depletion of the ore. Therefore, the accuracy of the measurement work is also very important for the impact of the mine's ore grade. In the later stage, it is necessary to increase the intensity of staffing and training of measurement technicians.
4 Conclusion
The accuracy of the basic geological data required by the mining designer is especially important for the construction quality and production connection. The quality of the construction project after the design is completed also determines whether the key factors of the mining body can be smoothly and maximally affected. The fluctuation range of the grade of the mine, therefore, the geotechnical, surveying and mining technicians in the mine production process should communicate frequently and work together to design and control, so as to “catch the pits and get out of the pits and then divide the homeâ€. In today's increasingly scarce resources, to some extent, the ore grade work can prolong the service life of mining enterprises. Especially at this stage, it is of great significance to increase the ore output rate.
In summary, there are many decisive factors for the grade of the ore, but the influence of the designer is the dominant factor. Therefore, grasp the main problem and then take effective measures to solve it, so as to continuously increase the economic benefits of the mining enterprises, and then turn losses into profits.
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    Source: Mining Technology: 2016.16(1);
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