Guide
In mining enterprises, the mining method determines the efficiency of the mining process, the amount of material equipment required, the amount of excavation work, the labor productivity, the ore recovery rate and the quality of the ore mined. Therefore, it must be given enough attention in the design. At the same time, due to the diverse conditions of ore bodies, the technical and economic conditions of each mine are different, so the mining method must choose the appropriate mining method according to specific conditions.
Section 1 Basic Requirements for Selecting Mining Methods
Proper and reasonable mining methods must meet the following requirements:
The mining method chosen for safety must ensure that workers can be safely produced during the mining process. Good working conditions (such as reliable ventilation and dustproof measures, suitable temperature and humidity) can mechanize heavy work and ensure mines. It can be produced safely and continuously, such as avoiding damage caused by large-scale ground pressure activities, preventing damage from surface landslides and mudslides caused by large blasting vibrations and post-harvest rock movements, preventing groundwater disasters, fires and other disasters.
The mining method of small ore depletion is to be depleted and the ore quality is high, meeting the requirements of the processing department for ore quality. Such as mining open-hearth iron-rich ore, waste rock can not mix ratio is too high and too fine ore, the ore can order directly into the open hearth. The impact of ore depletion on the quantity, cost and profitability of mining products (concentrates) is significant. Under normal circumstances, the ore cargoization rate is marked below 15%-20%.
Note:
1. During the mining process, some or some of the industrial reserves that cannot be produced or collected are not completely transported out of the earth's surface and lost underground. Any reduction in the amount of ore produced during the mining process is called ore loss.
2. The ratio of industrial reserves to industrial reserves lost during the mining process is called the ore loss rate. The ratio of pure ore produced to industrial reserves is called ore recovery rate. Both the loss rate and the recovery rate are expressed as a percentage (%).
3. In the mining process, not only the loss of ore, but also the quality of the ore is reduced, called ore depletion. It has two representations: the ratio of the amount of waste rock mixed into the produced ore to the amount of ore produced is called the waste rock mixing rate; it is caused by the amount of waste rock mixed and the loss of high-grade fine ore in individual cases. The percentage of ore grade reduction is called the ore depletion rate. The incorporation of waste rock during the mining process is the main cause of the depletion of ore. It is mainly in the process of falling mine, because the control of the ore body boundary is not good, the stone is not removed and the ore is discharged under the overburden.
The second section of mining index
The two indicators of ore loss and depletion are the main indicators for evaluating mineral deposits, each indicating the utilization of underground resources and the quality of ore mined. In metal mining deposits, reducing the rate of loss of ore, waste rock mixed rate and dilution rate, it has great significance. This has great significance for making full use of the national underground resources and extending the life of mining enterprises. At the same time, the loss of ore will inevitably reduce the amount of ore produced, which in turn will increase the cost of capital allocated to the ore mined per ton and increase the cost of mining ore. As another example, a 100 * 104t annual copper ore mines, 1% of the recovered copper ore grade, ignoring losses in the process, excluding, can produce ten thousand tons of copper annually. When the ore grade is reduced by 0.1%, one thousand tons of metal copper is produced less every year. The increase in the rate of waste rock mixing will inevitably increase the cost of ore transportation, upgrading and processing. At the same time, the lower grade of ore will also lead to a reduction in the metal yield and final product quality of the beneficiation process. Therefore, the economic losses caused by the depletion of ore are enormous.
High ore mining rate The mineral resources are limited and cannot be regenerated. Mining is an exhaustive production, so mining methods with high recovery rates are required to make full use of underground resources. In addition to having a certain impact on ore costs, ore losses also reduce total profit and shorten mine production time. Generally, the ore recovery rate should be between 80% and 85%. For the rich ore, rare metals and precious metal deposits with high mining value, the mining method with high recovery rate should be selected as much as possible.
High production efficiency should choose mining methods with high production capacity and high labor productivity. Different mining methods, the number of stages of simultaneous mining, the number of nuggets that can be arranged in one stage, and the production capacity of the nuggets are also different. The choice of mining method is generally considered in terms of the number of nuggets arranged in a recovery stage to meet the mine production capacity. The length of the return mining block is preferably less than two-thirds of the length of the stage working line.
High production efficiency can reduce the number of working nuggets at the same time, and it is convenient for the implementation of centralized mining to facilitate production management and mining site pressure management.
Economic benefits High economic efficiency mainly refers to the level of mining products and the size of profit. The profit indicators have the most comprehensive nature, such as the cost of ore and the loss of ore, which have an impact on profitability. Choose a profitable mining method.
Compliance with relevant regulations requires that mining methods must comply with the relevant regulations of mine safety, environmental protection and protection of mineral resources.
The above-mentioned combined requirements are interrelated and a comprehensive analysis of the above requirements must be made when selecting mining methods.
Section III Main Factors Affecting the Choice of Mining Methods
There are two main factors affecting the choice of mining methods: (1) geological conditions of the deposit; (2) technical and economic conditions for mining.
Deposit geological conditions
In general, it is necessary to first analyze the relevant geological data in detail, because the geological conditions of the mine are the basic factors affecting the choice of mining methods. Therefore, it is necessary to have sufficient and reliable geological data to select mining methods. Otherwise, it may be due to the improper selection of mining methods, causing damage to safe production and loss of mineral resources and economy.
The geological conditions of the deposit generally include the following:
Physical and mechanical properties of ore and surrounding rock In the physical and mechanical properties of ore and surrounding rock, the stability of ore and surrounding rock is important. It has a very important impact on the choice of mining methods. Because it determines the site pressure management method and the structure parameters of the stope.
For example, when the ore and surrounding rock are both stable, a simple open field mining method can be used to control the site pressure, and a larger mine size and a smaller pillar size can be selected. If the ore is stable and the surrounding rock is not stable, the surrounding rock is easy to fall by the empty field method. At this time, it is more advantageous to use the caving method and the flow filling method; on the contrary, if the ore is less stable and the surrounding rock is stable, and other Conditions such as thickness and inclination are appropriate, and the stage mining method is more effective because it avoids working directly on larger exposed surfaces. If the ore and surrounding rock are not stable, consider a caving method or a down stratified filling method.
Ore body ore body shape mainly refers to dip angle, thickness and shape.
The dip angle of the ore body mainly affects the way the ore is transported in the stope, and the influence of the dip angle on the transport is also related to the thickness. Only when the ore body inclination angle is greater than 50°-55°, it is possible to use the ore to carry out heavy weight transportation; when using the retention method, the inclination angle should be greater than 60°, but the thicker ore body can be free from these restrictions. At this time, the lower funnel can be excavated, and the ore is still reliably transported by weight. When the ore body inclination angle is not large enough, such as 30 ° -50 °, when other conditions permit, you can consider the explosive force transport or the self-weight transport by means of the chute. For ore bodies below 30°, it is often more effective to transport them with electricity. When using the caving method but the ore body inclination angle is less than 65°, then the lower plate rock should be excavated by drilling the lower funnel or the bottom of the nugget to reduce ore loss.
The thickness of the ore body affects the choice of the mining method and the method of mining and the arrangement of the nuggets. For example, the mining method of Hefei thin ore body below 0.8m should consider mining (such as sub-production filling method) or mixed mining (such as retention method); single-layer caving method generally requires ore body thickness not more than 3m; The caving method requires a thickness greater than 6-8 m; the stage caving method requires a thickness greater than 15-20 m. In the method of falling mine, shallow hole ore is often used for ore bodies less than 5-8m thick; medium and deep hole ore is often used for ore bodies with thickness greater than 5-8m; deep hole blasting is used for thicknesses above 10m; Thickness is required to be larger than deep hole blasting.
Generally, in thick and extremely thick ore bodies, the nuggets should be arranged vertically.
The shape of the ore body and the contact between the ore and the surrounding rock also affect the method of mining. If the contact surface is not obvious, the shape of the ore body is irregular, and the mining method using deep hole falling or falling in the chamber will cause large ore loss and depletion.
If the shape of the ore body of the extremely thin vein is regular, and the contact between the ore and the surrounding rock is obvious, the mining method of mining should be adopted; otherwise, the mining method of mixed mining should be adopted.
Mining methods with higher ore grades and higher value fortensive mining, higher value precious metals or national scarce metals (such as nickel , chromium, etc.) apply mining methods with higher recovery rates, such as filling methods. Conversely, it is advisable to use cost-effective mining methods such as segmentation or stage caving mining.
When the distribution of useful components in the ore body and the distribution of useful components in the mineral composition of the surrounding rock are uneven and vary widely, the mining method of mining should be considered, and the ore or rock with low grade can be left as a pillar.
If the surrounding rock has mineralization, the limitation of the surrounding rock mixing during the mining process can be appropriately relaxed. At this time, the deep hole falling mining method can be adopted. When the mineral composition of the surrounding rock is unfavorable for beneficiation and smelting, a mining method with a low waste rock mixing rate should be used.
When the ore body is buried deep, when the depth of the ore body is deep, 500-600m or more, the ground pressure will increase, and the impact pressure will be generated. At this time, the empty field method should not be adopted, and it is more suitable to adopt the caving method or the filling method.
The self-ignitability and agglomeration of ore and surrounding rock should be considered when there is a risk of spontaneous combustion. High-sulfur (more than 30%-40% sulfur) ore is highly likely to cause fires (sulphide ore with a sulfur content of about 20%, but also spontaneous combustion). At this time, it is not appropriate to use a large amount of backlog and backlog time. Long mining methods, such as the retention method and the stage collapse method.
In addition, the presence of agglomerated ore (higher sulphur ore, agglomerated kaolin ore) has the same requirements for preventing the spontaneous combustion of ore in the choice of mining method.
Mining technical and economic conditions
Mining technical and economic conditions have the following:
Whether the surface is allowed to fall within the range of the surface moving belt. If there are rivers, railways and important buildings, or because the environment is required to protect the environment, the surface is not allowed to fall. At this time, the caving method and the empty field method of the post-harvest caving area cannot be selected; Mining methods that maintain the goaf without causing large-scale movement of surface rock formations, such as cementation filling, or sand-filling when the ore body is not thick, or a certain number of pillars in the thick ore body and Mining method to fill the goaf.
The processing department's technical requirements for ore quality, such as the processing department, stipulate the minimum ore grade, thus limiting the maximum depletion rate of the mining method; and such as the allowable content of powder ore (rich iron ore), ore grade classification, etc. Both affect the choice of mining methods.
Technical equipment and material supply When selecting mining methods that require a large amount of special materials (such as cement, wood), you need to know the availability of these materials. Mining methods that do not use or use less wood should be chosen as much as possible. The source of cement and filler should be considered if a finishing method is to be used to fill the mining method.
The process and structural parameters of the mining method are closely related to mining equipment. Equipment availability must be considered when selecting mining methods. For the mining method of scraper mining and deep hole mining, it is necessary to know the relevant equipment supply and equipment performance in advance.
The mining method selected by the technical management level required by the mining method should be simple in technology, easy to grasp and easy to manage. This is especially important for small and medium-sized mines and local mines. Mining methods should be actively organized when selecting mining methods that are technically complex and unfamiliar to the mine. For example, the wall caving method should be often topped, which is difficult to master; the method of retaining ore in the open field method is easier to master than the method of sectioning rock drilling. If both methods are available, such as small mines, the technical strength is weak. , using the retention method may receive good results.
The above-mentioned factors affecting the choice of mining methods have different effects at least under different conditions. We must conduct specific analysis for specific situations, comprehensively and comprehensively consider and select the optimal mining method.
Section 4 Selection of Mining Methods
After conducting in-depth investigations on the geological conditions of the deposit, obtaining sufficient relevant data, and understanding the economic conditions of the mining technology, the mining method can be selected according to the basic requirements mentioned above.
The first step: primary selection of mining methods;
The second step: technical and economic analysis;
The third step: detailed technical and economic calculations, comprehensive analysis and comparison.
In the practice of mining method selection, it is often the case that after the initial selection of several schemes, after preliminary technical and economic analysis, that is, in the second step, the advantages and disadvantages are discriminated and the best solution is selected. Only after the technical and economic analysis, the third step is compared with the 2-3 schemes that are still difficult to distinguish between good and bad, detailed technical and economic calculations are carried out for each scheme, and comprehensive analysis is carried out according to the calculation results to select the optimal scheme. .
In the selection of mining methods, the following points are added:
Improve the accuracy and integrity of the geological data of the deposit, especially regarding the stability and robustness of the rock. There have been examples of large economic losses caused by insufficient data and incorrect selection, resulting in a large loss of ore and long-term failure to reach production.
When the geological conditions of the deposit are relatively complicated, it is required to complete the industrial experiment of the mining method during the infrastructure period. After the experiment is successful, the mining method can be finally selected.
In the analysis and comparison of mining methods, it is necessary to note the extent of the impact due to different methods. For example, the empty field method and the filling method, the comparison project includes not only the mining room mining, but also the mining column mining, and sometimes the empty area processing project.
The choice of mining method is not just a better way to choose from the existing methods. Sometimes it is necessary to combine the geological conditions and requirements of the deposit, creatively apply the process and structure knowledge of the existing mining methods, and propose new mining methods that are more in line with the requirements.
Mining method primaries
According to the above conditions and requirements, firstly, some mining method schemes are proposed for technical possibilities; secondly, according to the main advantages and disadvantages of each scheme, the schemes with obvious shortcomings are eliminated.
The main purpose of this step is to propose a technically feasible mining method solution that does not have significant shortcomings.
This step is very important. It is often based on some shortcomings in the initial proposal, and proposes improvements and innovations to form a more appropriate new solution. More efforts should be made in the primary elections, especially when the geological conditions of the deposits are complex, so extensive investigation should be conducted to avoid leaving the best solution.
Technical and economic analysis of the fifth section of mining methods
For each scheme of primary selection (generally no more than 3-5), determine its main structural parameters, select the cutting arrangement and mining process, select representative nuggets, and draw a standard map of the mining method plan, calculate Or use the analogy method to select the following technical and economic indicators of each program, and analyze and compare accordingly, and select the best:
Nugget labor productivity;
Appropriate cutting workload and time;
Nugget production capacity;
Main material consumption (pits and explosives, etc.);
Loss rate and depletion rate of ore;
The direct cost of producing ore.
These indicators are generally not calculated in detail, but are selected according to the actual data indicators of mines based on the requirements of the mining method.
In addition to analyzing and comparing these indicators, we should also fully consider the safety level of the program, working conditions, and the complexity of the process. Sometimes you have to pay attention to the amount of infrastructure, capital investment and infrastructure time associated with mining methods (for example, when using cementation filling or water sand filling).
When analyzing and comparing the above indicators, it is often said that for the same program, these indicators are not all superior, but some are good and some are poor. In this case, it is necessary to look at the size of the difference between these indicators, and under the specific conditions of the mine, which indicators are the main to determine the program. Separate the primary and secondary, and focus on it. The purpose of the focus is to better achieve economic results in order to more specifically combine national requirements. For example, depletion indicators are even more important when mining rich minerals and scarce metals that are particularly needed by the state. If it is a poor mine and has a large inventory, it should consider the use of high efficiency and low cost mining methods. In short, we must make specific analysis according to specific situations and grasp the main contradictions to solve the problem.
In most cases, after such a technical and economic analysis, it is possible to determine which mining method to adopt. In a few cases, a comprehensive analysis comparison is needed to determine the best solution.
Comprehensive analysis and comparison of mining methods
After the above analysis and comparison can not determine the pros and cons, the detailed technical and economic calculations of the 2-3 mining method schemes that are difficult to distinguish are calculated and the relevant indicators are calculated. Based on these indicators, a comprehensive analysis and comparison is carried out, and finally the optimal solution is selected.
Selection example
An iron deposit has a length of 350m, an inclination of 60°-°70, and an average thickness of 50m. The ore body has good continuity, regular shape and simple geological structure. The ore is magnetite-containing, dense and hard, f=8-12, which is moderately stable. The upper plate is marble , not stable enough, f=7-9, karst development; the lower plate is skarn plagioclase and granodiorite porphyry, due to weathering, poor stability. The grade of ore is relatively high, with an average copper content of 1.73% and an average iron content of 32%. The annual output of ore produced by the mine is 43*104t.
The method primary selection selects the available mining methods based on the above-mentioned mining bed technical conditions.
Due to the poor stability of the surrounding rock, the empty field method is not applicable. Depending on the value of the ore, the stability of the surrounding rock and ore, and the size of the deposit, an up-level horizontal stratification method can be used.
According to the medium stability of the ore, the poor stability of the surrounding rock, the dip angle and thickness of the ore body, and the allowable subsidence of the surface, the sublevel caving method and the stage forced caving method of the caving method can be used. In the sublevel caving method, the bottoming column has a large amount of mining and cutting work, the bottom structure is complex, and the ore loss is large; the bottomless column method structure and the mining process are simple, safe, and highly mechanized. According to the design conditions, the ore loss is poor. It may be smaller than the bottomed column method. The bilgeless method has poor ventilation and can be attenuated in the case of a well ventilated system and enhanced ventilation. According to this, the sublevel caving method with the bottom column is deleted. As for the staged forced caving method, the ore loss is more materialized, and the flexibility is not as good as the sub-column sublevel caving method. Especially considering the high grade of ore, it is not suitable.
Thus, the mining methods available for this deposit are:
Sublevel caving method without bottom column.
Upward horizontal stratification filling method; according to different mining method, it can be divided into two schemes.
The specific plan is as follows:
The first scheme: the sublevel caving method without bottom pillar. The section height is 10m, the distance of the mining roadway is 10m, and the vertical direction is arranged. The CZZ-700 rock drilling rig is used for rock drilling and the ZYQ-14 loader is used for mining.
The second scheme: divided into mining room and pillar, the mine is 10m wide and the pillar width is 5m. The mine is harvested by the upward horizontal layered tailings filling method. The pillar is recovered by the method of leaving the ore and is cemented afterwards. First mining column, rear mining room. The YSP-45 rock drill is used for rock drilling and the ZYQ-14 loader is used for mining.
The third scheme: the mine is 10m wide, and is harvested by the upward horizontal layered tailings filling method, and the wall is built by the pillars. The pillar is 5m wide and is harvested by sublevel caving without a bottom column. The YG-80 medium-deep rock drill was used for rock drilling and the ZYQ-14 loader was used for mining.
The technical and economic analysis is based on the analysis of the main technical and economic indicators such as the production capacity of the nuggets, the mining workload, the loss rate of the ore, the depletion rate, and the labor productivity. As can be seen from the above table, although the loss rate and depletion rate of ore are lower in the second scheme, the production capacity of the ore and the labor productivity of the whole staff are lower than the other two schemes, and the cementation filling process is complicated, and two sets of filling are required. The system consumes a lot of cement every year, so this plan should be deleted.
Compared with the third scheme, the first scheme has a large production capacity of the ore block, high labor productivity, simple mining process and high degree of mechanization, but high ore loss rate and depletion rate. Therefore, further detailed calculations are needed, and finally the comprehensive analysis and comparison can be selected.
Comprehensive analysis and comparison The detailed technical and economic calculations are carried out for the first and third schemes determined through preliminary technical and economic analysis. According to the design conditions, calculate the production capacity, the amount of cutting engineering, the ore recovery rate, the ore depletion rate, the concentrate production, the labor productivity, the capital investment, the mining cost per ton of ore, and the profit amount. Analyze and contrast, and finally comprehensively weigh the results, and determine the third option, that is, the mining room with the upward horizontal layered tailings filling method, and the pillars with the bottomless sublevel caving method.
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