Mining method selection

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:

1) Improve the requirements for the accuracy and completeness of the geological data of the deposit, especially regarding the stability and robustness of the ore. 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.

2) When the geological conditions of the deposit are relatively complicated, it is required to complete the industrial experiment of the mining method in the period of capital construction. After the experiment is successful, the mining method can be finally selected.

3) 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.

4) The choice of mining method is not just a better method than the existing one. 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.

First, mining method primary selection

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.

Second, the technical and economic analysis 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:

1) labor productivity of ore workers;

2) Aligning the cutting workload and time;

3) production capacity of the ore block;

4) The consumption of major materials (pits and explosives, etc.);

5) Loss rate and depletion rate of ore;

6) The direct cost of mining 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, when the mining bonanza gold and scarce countries with special needs belong, depleted index is more important. 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.

Third, the 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.

Choice 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. High grade ore, containing an average of 1.73% copper, 32% average iron. The annual output of ore produced by the mine is 43*104t.

1. Method Primary Selection According to the above-mentioned mining bed technical conditions, the available mining methods are initially selected.

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:

1) Sublevel caving without sill.

2) Upward horizontal stratification filling method; according to different mining methods, 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.

2. Technical and economic analysis According to the main technical and economic indicators such as the production capacity of the nuggets, the mining workload, the loss rate of ore, the depletion rate and the labor productivity. The main technical and economic indicators for the three programmes are listed in the table below:

Comparison table of technical and economic indicators for mining methods:

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.

3. 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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