Blast-hole stemming material and preparation method for open-pit mine blasting

Abstract

A blast-hole stemming material for open-pit mine blasting comprises a composite structure composed of a geopolymer stemming material and a rock powder stemming material. The geopolymer stemming materi

Description

TECHNICAL FIELD

[01] The invention relates to the field of mine blasting technology, especially to a blast-hole stemming material and preparation method for open-pit mine blasting. BACKGROUND ART

[02] Nowadays, the open-pit mine blast-hole stemming is still mainly caused by rock powder stemming, the length of the stemming is estimated by the experience of the field construction personnel, and the stemming operation is completed by the excavator-assisted artificial shovel in a semi-mechanical and semi-artificial way, which has limitations and blindness, simple rock powder stemming has certain drawbacks. In order to ensure the stemming quality and prevent punching, a long stemming length is required. On the one hand, it reduces the amount of charge in the upper part of the blast hole and lowers the charge center, which is not conducive to improving the blasting quality of the upper rock. On the other hand, the length of the charge is reduced, and the optimization space of the charge structure is compressed. In addition, it also reduces the utilization rate of blast holes, and requires more dense hole network parameters to achieve the amount of explosives required for rock blasting, resulting in an increase in the amount of work and an increase in economic costs.

[03] At present, the mining industry in China is undergoing the transformation and upgrading of the overall production process, and intelligent mechanized operations are gradually replacing manual operations. Engineering blasting is the first link of mining technology, and improving the quality of stemming is an important way to optimize the blasting process. In the past, due to the manual operation of the hole stemming, the harsh operating conditions that the stemming material cannot be widely used will be relaxed. In recent years, material modification has become a research hotspot in the engineering fields of mining, civil engineering, and construction. A lot of research and practical applications of material modification have been carried out in the fields of construction, road, and filling mining. Therefore, the modification and application of blast-hole stemming materials in open-pit mines has become an important basic direction for future mine development. Good hole stemming can increase the action time of detonation gas, promote the further expansion and deepening of detonation gas along the hole wall cracks, increase the degree of rock mass fragmentation, improve the ability of explosives to expand and work on rock mass fragmentation, reduce invalid work and harmful work, reduce the leakage of explosive energy, and effectively reduce the harm of flying rock, noise pollution and blasting vibration intensity.

[04] Shangguan Jianming et al. used the high-efficiency water cannon mud and the polyurethane foaming glue to form a new hole-stemming material, by comparing the concentration of respirable dust and total dust of high-efficiency water cannon mud with different component ratios after blasting and analyzing the physical and mechanical properties of polyurethane foaming glue, the conclusion was drawn, it was concluded that high-efficiency water cannon mud can play the role of cooling and dust reduction, and polyurethane foaming glue can prolong the action time of detonation gas. Therefore, the combination of new hole-stemming materials has broad development prospects. Li Guoping et al. used fine road material gravel as the stemming material and earned out a comparative test in Dexing Copper Mine, the test results showed that the stemming effect of fine road material is obviously better than that of rock powder, under the same stemming length, the punching rate can be reduced by about 7 %, and the bulk rate can be reduced by about 4 %, and it is safer. However, from the perspective of operation and construction, the manual operation intensity of fine road material stemming is large and the operation efficiency is low compared with rock powder stemming. Zhang Zheng mixed ore powder, density regulator, adhesive, and water-retaining agent into stemming gun mud, in which the weight ratio of ore powder was 30-90, density regulator was 0-40, adhesive was 1-2, and the water-retaining agent was 0.1-0.5. Yan Changhuai et al. made different specifications of stemming materials by adding 0.03 %-0.05 % binder and water to the tailings sand filter cake. Guo Yuanjun used water starch as the application of blasthole stemming to seal the blasting hole and achieved certain results. Wu Tianming matched a kind of blasting hole plugging cementitious material with rapid solidification, early strength, and micro-expansion characteristics, which can rapidly solidify and have certain expansibility. SUMMARY [05J The purpose of the invention is to provide a modified blast-hole stemming material and preparation method for open-pit mine blasting, which is used to solve the problems of high cost, long maintenance time, low environmental protection, failure to quickly achieve blast hole plugging, and low blasting quality.

[06] In order to achieve the above purposes, the invention provides a blast-hole stemming material for open-pit mine blasting, including a blast-hole stemming material, the blast-hole stemming material is a composite structure composed of a geopolymer stemming material and a rock powder stemming material, an upper part is the geopolymer stemming material, and a lower part is a rock powder stemming material.

[07] Preferably, the geopolymer stemming material includes rock powder, slag, water glass, sodium hydroxide, and water.

[08] Preferably, in terms of mass percentage, the geopolymer stemming material includes 60 % rock powder, 17 % slag, 3 % NaOH solution with a mass fraction of 30 %, 12 % water glass with a modulus of 3,2, and 8 % water.

[09] Preferably, the water glass is liquid sodium silicate.

[10] A preparation method of blast-hole stemming material for open-pit mine blasting, including the following steps: firstly, preparing the geopolymer stemming material; secondly, filling the geopolymer stemming material in a blast-hole as the upper part of the blast-hole stemming material; thirdly, filling the rock powder stemming material in the blast-hole as the lower part of the blast-hole stemming material.

[11] Preferably, the preparation method of the geopolymer stemming material includes the following steps:

[12] SI, ratio, in terms of mass percentage, taking 60 % rock powder, 17 % slag, 3 % NaOH solution with a mass fraction of 30 %, 12 % water glass with a modulus of 3.2, 8% water for backup;

[13] S2, preliminary screening, spreading the slag, and rock powder raw materials evenly in a tray, where the rock powder is applied for preliminary screening to screen out the rock slag blocks with large particle size;

[14] S3, mixing and stirring, mixing the slag powder with the rock powder solid material and pouring it into the cement mortar mixer to mix evenly;

[15] S4, mixing additives, mixing water, sodium hydroxide solution, and water glass, pouring the mixture into a mixer, and stirring until the mixture is uniform to obtain the geopolymer stemming material.

[16] Preferably, in SI, the NaOH solution configuration refers to the experimental procedure of chemical preparation solution, the sodium hydroxide solution is configured with caustic soda, and the sodium hydroxide solution is cooled during configuration.

[17] Preferably, in S3, the mixer is continuously stirred until the mixed material is in a flowing slurry state, the mixed material is filled into the blast hole, and the normal temperature and curing time are selected for 2h.

[18] Therefore, the invention adopts the blast-hole stemming material and preparation method for open-pit mine blasting provided in the above content to realize the following beneficial effects:

[19] (1) The traditional hole-stemming material achieves the purpose of stemming through its gravity, and the cohesive force is very weak, which makes the blasting phenomenon easy to occur in the blasting process. According to the test, the filling capacity of the filling material per unit length involved in the invention is more than 100 times that of the rock powder filling, which can reduce the labor intensity of the filling work and avoid the occurrence of the blasting phenomenon.

[20] (2) Compared with other materials, the geopolymer material has the characteristics of excellent mechanical properties, fire resistance, high-temperature resistance, fast curing speed, and high early strength.

[21] (3) The curing speed of the material is fast, the early strength is high, and the normal blasting operation time will not be affected by the long curing time.

[22] (4) Compared with the original rock powder filling, it can improve the energy utilization rate of explosives and optimize the block distribution.

[23] (5) Raw materials belong to industrial waste, which has a wide range of economic and environmental protection sources. At the same time, it consumes industrial solid waste produced by mines and surrounding industrial enterprises, forming a circular economy model centered on open-pit mines, and driving the healthy and sustainable development of mines and surrounding industrial enterprises.

[24] (6) The original rock powder plugging is adjusted to a composite structure of geopolymer stemming material and rock powder plugging, the upper part is geopolymer stemming material, and the lower part is rock powder. Under the premise of ensuring the blasting quality, the application of geopolymer materials optimizes the blasting effect, only one link of the stemming operation needs to be changed, and there is no economic burden risk.

[25] The following is a further detailed description of the technical scheme of the invention through drawings and an embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

[26] Fig. 1 is a flow chart of the blast hole stemming material and preparation method for open-pit mine blasting. DETAILED DESCRIPTION OF THE EMBODIMENTS

[27] The invention adopts a blast-hole stemming material for open-pit mine blasting, including a blast-hole stemming material. The blast-hole stemming material is a composite structure composed of a geopolymer stemming material and a rock powder stemming material, the upper part is the geopolymer stemming material, and the lower part is a rock powder stemming material. The geopolymer stemming material includes rock powder, slag, water glass, sodium hydroxide, and water. In terms of mass percentage, the geopolymer stemming material includes 60 % rock powder, 17 % slag, 3 % NaOH solution with a mass fraction of 30 %, 12 % water glass with a modulus of 3.2, and 8 % water. The water glass is liquid sodium silicate.

[28] A preparation method of blast-hole stemming material for open-pit mine blasting, including the following steps: firstly, the geopolymer stemming material is prepared; secondly, the geopolymer stemming material is filled in a blast-hole as the upper part of the blast-hole stemming material; thirdly, the rock powder stemming material is filled in the blast-hole as the lower part of the blast-hole stemming material.

[29] The preparation method of the geopolymer stemming material includes the following steps:

[30] S1, ratio, in terms of mass percentage, 60 % rock powder, 17 % slag, 3 % NaOH solution with a mass fraction of 30 %, 12 % water glass with a modulus of 3.2, 8% water are taken for backup;

[31] S2, preliminary screening, the slag, and rock powder raw materials are evenly spread in a tray, where the rock powder is applied for preliminary screening to screen out the rock slag blocks with large particle sizes;

[32] S3, mixing and stirring, the slag powder is mixed with the rock powder solid material and poured into the cement mortar mixer to mix evenly;

[33] S4, mixing additives, water, sodium hydroxide solution, and water glass are mixed and poured into a mixer, and stirred until the mixture is uniform to obtain the geopolymer stemming material.

[34] In SI, the NAOH solution configuration refers to the experimental procedure of chemical preparation solution, the sodium hydroxide solution is configured with caustic soda, and the sodium hydroxide solution is cooled during configuration, in S3, the mixer is continuously stirred until the mixed material is in a flowing slurry state, the mixed material is filled into the blast hole, and the normal temperature and curing time are selected for 2h.

[35] Experimental principle: In this method, a polycondensation reaction can be produced between the slag and the activator, so that a stemming material with strength can be obtained, a blast-hole stemming material with excellent mechanical properties, fire resistance, high-temperature resistance, fast curing speed, and high early strength can be obtained. This method uses polymer as a stemming material, which can obtain a stemming material with stable performance and high strength. At the same time, its steps are simple and the manufacturing cost is low, which is suitable for a wide range of promotion and use.

[36] Take the application of bench blasting field test engineering in Pingshuo East Open-pit Mine of China Coal as an example.

[37] When blasting for an open-air stage, the maximum block size of the test area is 127cm, of which nearly 90 % of the rock block size is below 57.11cm. Based on the needs of pre-installation, shovel, crushing station feeding, and on-site construction, the critical size of the block is located at 1.2m, and the block rate in this area is nearly 0 %. That is, from the block characteristics of the surface reaction of the blasting pile, the blasting effect is very good, and there are almost no large blocks. The maximum block size of the contrast area is 150 cm, of which nearly 90 % of the rock block size is below 65.36 cm.

[38] The experimental process: the drilling form is vertical drilling, the aperture is 250 mm, and the ultra-deep is 1.5 m. For the convenience of construction, the holes were arranged in a rectangular way, with a hole spacing of 8 m and a row spacing of 7 m. The porous granular ammonium nitrate explosive produced by Shanxi China Coal Pingshuo Explosive Equipment Co., Ltd. was adopted, the detonation system adopted the Aureka EXEL conventional non-electric detonation detonator, Cordtex™ detonating cord and Pentex™ detonation device, and the spacer adopted the air spacer series produced by Shanxi China Coal Pingshuo Explosive Equipment Co., Ltd. series air spacer. The detonation sequence was diagonally initiated. The delay between the first rows of holes was 42 ms, the delay between the rear rows was 60 ms, and the delay of the detonator in the hole was 600 ms. Shovel mining and loading operation was used to clean up the explosive pile, there was no need for key protection objects within 300 m around the working site, and the environmental conditions were good. In the contrast area, the porous granular ammonium oil explosive was used for segmented charging, and the overall stemming was 6.0-7.5 m; the porous granular ammonium oil explosive was used for segmented charging in the test area. The middle air spacer was separated by Im, and the stemming adopted a composite structure. 2m in the upper part was geopolymer, and 3.5m in the lower part was rock powder stemming. According to the mass percentage, 253 kg of rock powder was selected and mixed with 72 kg of slag, and 15 kg of NaOH solution (30 %), 51 kg of water glass with a modulus of 3.2, and 30 kg of water. After the geopolymer blast-hole stemming material was prepared according to the above method, the prepared material was filled into the hole according to the use method, and the detonation experiment was carried out.

[39] Experimental results: In the high-speed photography record, the stemming initiation of the stemming material test area and the original rock powder stemming comparison area formed a significant comparison. Among them, the overall plugging situation of the material test area is better, except for one small punching that occurred in the southwest comer, but the punching height does not exceed 10 m. In the middle of the original rock powder plugging comparison area, there are two large-scale punchings, the plugging impulse and the rock around the orifice are washed out in large quantities, and the punching height reaches 30 m. A small-scale punching occurred at the north boundary, and the punching height is about 10 m. It can be seen that the geopolymer stemming material has better plugging performance than the original rock powder plugging.

[40] Therefore, the invention adopts the blast-hole stemming material and its preparation method for open-pit mine blasting to replace the traditional rock powder stemming material, which has the characteristics of low production cost, good environmental protection performance, and wide source range. The material has simple preparation steps, short curing time, and high early strength, which can quickly achieve the effect of blast-hole stemming and improve the blasting quality.

[41] In the description of the invention, it should be noted that the orientation or positional relationship indicated by the terms 'up',' down',' inside',' outside', etc. is based on the orientation or positional relationship shown in the attached figure, or the orientation or positional relationship usually placed when the product of the invention is used. It is only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or component must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a restriction on the invention.

[42] Finally, it should be noted that the above embodiment is only used to explain the technical scheme of the invention rather than to restrict it. Although the invention is described in detail concerning the better embodiment, the ordinary technical personnel in this field should understand that they can still modify or replace the technical scheme of the invention, and these modifications or equivalent substitutions can not make the technical scheme out of the spirit and scope of the technical scheme of the invention.

Claims

1. A blast-hole stemming material for open-pit mine blasting, including a blast-hole stemming material, the blast-hole stemming material is a composite structure composed of a geopolymer stemming material and a rock powder stemming material, wherein the geopolymer stemming material is an upper part of the blast-hole stemming material, and the rock powder stemming material is a lower part, below the upper part, of the blast-hole stemming material.

2. The blast-hole stemming material for open-pit mine blasting according to claim 1, wherein the geopolymer stemming material includes rock powder, slag, water glass, sodium hydroxide and water.

3. The blast-hole stemming material for open-pit mine blasting according to claim 2, wherein in terms of mass percentage, the geopolymer stemming material includes 60 % rock powder, 17 % slag, 3 % NaOH solution with a mass fraction of 30 %, 12 % water glass with a modulus of 3.2, and 8 % water.

4. The blast-hole stemming material for open-pit mine blasting according to claim 3, wherein the water glass is liquid sodium silicate.

5. A preparation method of a blast-hole stemming material for open-pit mine blasting according to any of the claims 1-4, including the following steps:firstly, preparing the geopolymer stemming material; secondly, filling the geopolymer stemming material in a blast-hole as the upper part of the blast-hole stemming material; thirdly, filling the rock powder stemming material in the blast-hole as the lower part, below the upper layer, of the blast-hole stemming material.

6. The preparation method of the blast-hole stemming material for open-pit mine blasting according to claim 5, wherein including the following steps:SI, ratio, in terms of mass percentage, taking 60 % rock powder, 17 % slag, 3 % NaOH solution with a mass fraction of 30 %, 12 % water glass with a modulus of 3.2, 8% water for backup;S2, preliminary screening, spreading the slag, and rock powder raw materials evenly in a tray, where the rock powder is applied for preliminary screening to screen out the rock slag blocks with large particle size;S3, mixing and stirring, mixing the slag powder with the rock powder solid material and pouring it into the cement mortar mixer to mix evenly;S4, mixing additives, mixing water, sodium hydroxide solution, and water glass pouring the mixture into a mixer, and stirring until the mixture is uniform to obtain the geopolymer stemming material.

7. The preparation method of the blast-hole stemming material for open-pit mine blasting according to claim 6, wherein in SI, the NAOH solution configuration refers to the experimental procedure of chemical preparation solution, the sodium hydroxide solution is configured with caustic soda, and the sodium hydroxide solution is cooled during configuration.

8. The preparation method of the blast-hole stemming material for open-pit mine blasting according to claim 6, wherein in S3, the mixer is continuously stirred until the mixed material is in a flowing slurry state, the mixed material is filled into the blast hole, and the normal temperature and curing time are selected for 2h.

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