Study on the mixing of two-step segmentation empty field and post-filling mining method

1 Overview

Heavy DONGPING gold ore mine mainly at two subsequent steps sublevel open filling method, mineral ore body block is arranged vertically, the horizontal length of the thickness of the ore body, wide 30m, pillar width 10m, 20m wide stope The bottom column is 10m (including the roadway), the section height is 10m, and the middle section height is 40m. The bottom structure adopts the bottom structure of the trench and the scraper is used for mining. In one step, the 10m wide pillar is first recovered, and after the tailings are cemented, the second step is to recover the 20m mine. The mining method currently used is mature in the Dongping Gold Mine and is easy to operate.
When the Dongping Gold Mine is mining the second-step mining house, the tailings of the tailings are mixed into the ore that has been mined to varying degrees, resulting in a larger pH value of the pulp in the plant, a flotation trough, a lower recovery rate of the ore , and a tailing grade. It stays high, reaching a maximum of 0.8-0.9g/t, causing serious economic losses. Through the analysis and research, the selection technicians finally determined that it was due to
The infused ore is mixed into the ore, causing the pH value of the slurry to become larger and unstable, which affects the entire flotation process. Therefore, in order to maintain the stability of the flotation process and improve the recovery rate of the ore dressing, it is necessary to reduce the incorporation of the backfill in the ore.
2 analysis of the reasons for the filling of the filling body
In view of the problem of mixing the filling body in the original ore, through careful study and analysis of the entire mining process and field operations, the main reasons for the filling of the filling body are as follows:
(1) The strength of the filling body is not up to standard. According to the analysis of the strength of the filling body falling into the stope during the recovery process of the mine, it is found that the strength of the filling body does not reach the design strength, which results in the consolidation of the pillars in one step of cementation filling is not strong. This causes the pillar to partially collapse.
(2) One step of mining the pillars for over-excavation. In the first step of mining the pillars, in the place where the fractures and structural planes develop, the ore body range that is actually exploded exceeds the design range of the pillars due to the instability of the ore body, that is, the two-step mine is over-excavated in one step of the pillar recovery. The scope of mining. After the first step of mining, since there is no measurement of the empty area after the mining of the pillar, the design of the blasthole enters the filling body during the two-step mining, which leads to the filling of the over-excavation part of the next step in the second-step mining. Depletion of ore.
(3) The blasting vibration destroys the pillar filling body. When the mining site is harvested, the phenomenon of blasting vibration is destroyed by the on-site observation. During the mining period of the mine, the integrity of the pillar filling body is affected by the blasting vibration, and some of the filling body falls off and falls into the caving. In the ore, it leads to secondary depletion of mining.
(4) Filling and running and management are not in place, resulting in depletion of mining. Due to the development of fissures, it is prone to run the slurry when filling the quarry, and a large number of filling bodies appear in the rock drilling roadway in each layer of the mine. Because the management is not in place, the running grout is not effectively treated. Into the ore; in addition, when filling the one-step pillar stop, the prospecting veins in some of the two-step stop are also filled, and they are not effectively treated. When the ore is mined, the ore is transported to the chute and transported to the well. Plant selection.
3 Study on the method of filling the filling body
3.1 Optimize the filling ratio and increase the filling strength
In order to simulate the actual environment in the underground as much as possible, the filling ratio and maintenance test are carried out in the well. The uniaxial compressive strength of the filling body at a ratio of 1:6, 1:8, 1:10, etc. at 7, 14, 28, and longer curing times was tested.
The test results show that the uniaxial compressive strength of the 1:10 filling body has not reached 1.5 MPa in the indoor experiment. The filling slurry concentration has a great influence on the filling body strength, and the high concentration slurry filling body has high strength. Therefore, when filling In the case of ensuring self-flow, it is necessary to increase the concentration of the filling body as much as possible; in addition, the strength of the filling body gradually increases with the prolonging of the curing time, especially in the 28d, the strength is increased faster. Therefore, when mining the second-step mining site, the filling of the stope should be completed in advance to ensure sufficient maintenance time of the pillar filling body and ensure the filling body strength.
The greater the strength of the cement, the greater the strength of the filling body. In the test, the strength of the filling body using the standard 42.5 composite Portland cement and the 1:6 lime sand ratio is higher than that of the 32.5 composite Portland cement, 1: 4 The strength of the filling body of the lime-sand ratio (see Figure 1 to Figure 2), the comprehensive cost calculation, in order to ensure the overall stability and integrity of the pillar filling body, the height of the filling body with a ratio of 1:10 to sand can be appropriately reduced.

3.2 "drilling" and "exploring" to determine the boundary of the mine

In view of the over-excavation problem of the mining quarry, during the second-step mining, the actual boundary of the mine is determined through the combination of “drilling” and “exploration” to reproduce the mine. Each layer is re-circled to the boundary of the mine every 9.80m in the design. The hole is guaranteed to be in a straight line on the section, which is beneficial to the subsequent delineation of the boundary. After the bottom is processed, the hole can be used as The blasting of the medium and deep hole drilling and utilization, to achieve "drilling" and "exploration" combination, saving engineering. At the same time, during the construction process, the designer goes to the well to carry out the work, to ensure that the actual construction distance of each row of holes is recorded. When the boundary of the design hole is reached, when the filling body is not seen, the hole is deepened until the filling body is hit; Exploring the hole situation, re-delimiting the boundary of the mine, and then designing a reasonable medium-deep hole blasthole, so that the mine blasting limit can be accurately determined, and the filling body can be ensured as much as possible.

At the same time, it is also possible to recover the ore lost from the original pillar stop due to the failure of the shot.
3.3 Reserve the mine wall to protect the pillar filling body
In the process of shooting, the blasting vibration destroys the problem that the filling of the pillar is stable and the filling body is mixed. The measures to reserve the mine wall and protect the pillar filling body are proposed. In order to protect the pillars and avoid the loss of ore body caused by the reserved ore wall, the test designed 0.5, 0.7, 0.8, 1.0m four sets of tests, and in the middle section of 1224, the 15S-28 stope was respectively left. The .5m mine wall test and the 1.0m mine wall test were carried out, and the 0.7m ore wall test and the 0.8m mine wall test were carried out in the 17S-8 stope in the middle of 1264. By observing and counting the damage and mixing of the filling body under the test conditions of each group, and the loss rate of the ore body, the results show that the mineral column filling body can be effectively protected while the ore wall is 0.7m thick. Does not affect the mining recovery.
3.4 Strengthen management and prevent running pulp
For the running of the filling body, a large number of filling bodies appeared in the rock drilling roadway in each layer of the mine, and the mining team was strengthened. Before the second step of mining, the filling bodies of each layer must be cleaned up, including the filling body of the previous prospecting and veining. After the qualified personnel have passed the inspection, the medium and deep hole blasting operations can be carried out; the training and training of the miners are strengthened. The reward and punishment system ensures that when the filling body is mixed in, the separation of the ore is carried out in time to avoid a large amount of filling body mixed into the ore during the mining.
4 Conclusion
Through technical breakthroughs, the above measures have been taken to improve the stability of the pillar filling body, and the mixing rate of the filling body is greatly reduced, and the mixing rate is reduced from 15% to less than 2%. The quality of the ore selected was greatly improved, the pH value of the flotation slurry was basically stable, the recovery rate of ore dressing was significantly improved, the grade of tailings was effectively controlled, and the economic benefits of the company were significantly improved.
references:
[1] Zhou Aimin. Mine waste cementation filling (Second Edition) [M]. Beijing: Metallurgical Industry Press.
[2] Qin Lina, Shang Zhihui. The effect of PH value on the flotation process [J]. Jiugang Technology, 2013 (4).
[3] Wang Shizhen, Yuan Jinfeng, Wang Zhihong. Stability analysis of post-filling method pillar [J]. Copper industry workers, 2014 (2).
[4] Huang Mingfa. Application of segmented empty field post-filling mining method in Longjiangting Copper Mine [J]. Mining Technology, 2015, 15(7).
[5] Yu Runcang. Mining Engineer's Handbook [M]. Beijing: Metallurgical Industry Press, 2009.

Article source: Mining Technology; 2017.17(2)

Author: Wang Aimin; Hebei Chongli Zijin Mining Co., Ltd., Hebei Chongli County 076 350

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