The influence of borehole arrangement of soundless cracking demolition agents (SCDAs) on weakening the hard rock

Tang, Wei; Zhai, Cheng; Xu, Jizhao; Cong, Yuzhou; Zheng, Yangfeng

doi:10.1016/j.ijmst.2021.01.005

Cited by 50 publications

(15 citation statements)

References 37 publications

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“…Before running the LS-DYNA 3D program, five elements are designated as observation points to facilitate analyzing and processing the numerical results [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. As shown in Figure 3, points H69786, H68778, H68787, H62503, and H61486 are selected at the lower part of the centerline of two blast holes, which are signed as A, B, C, D, and E, respectively.…”

Section: Simulation Results and Analysismentioning

confidence: 99%

Numerical Simulation on Selection of Optimal Delay Time for Precise Delay Blasting

Wang

et al. 2021

Shock and Vibration

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In the traditional presplitting blasting, the presplit holes are generally uniformly initiated, which causes local damage to the retained rock mass while forming the damping ditch. In order to determine the optimal delay time of the precise delay initiation hole by hole, the finite element software ANSYS/LS-DYNA is used to build a blasting model of the concrete, which includes concrete, explosive, and air to simulate the crack forming process of the presplitting hole under various initiation modes. Four kinds of initiation modes for blasting, namely, simultaneous initiation with 0 ms, 9 ms, 12 ms, and 15 ms of delay between adjacent holes, are set up to determine the exact delay time of the best presplitting effect. The simulation results show that when the prehole detonates simultaneously, the inner hole crack penetrates the fastest, but the peak stress around the hole is up to 147.9 MPa. When interhole delayed initiation is used, although the time of interhole crack penetration is prolonged, the stress coupling is generated around the precrack and the maximum stress is obviously reduced. The maximum stress generated under the three delayed initiation conditions is only 76.8 MPa. Considering the requirement of damage control of surrounding rock mass and the rapid formation of precrack, 9 ms delay time is determined as the precise delay time of this test.

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Section: Simulation Results and Analysismentioning

confidence: 99%

Numerical Simulation on Selection of Optimal Delay Time for Precise Delay Blasting

Wang

et al. 2021

Shock and Vibration

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“…Hydraulic fracturing is one of the mainstream physical reservoir stimulation methods; however, it mainly creates large-scale and single fractures [71] and is not appropriate for enhanced ISL mining. Silva et al [72] proposed a method to induce fracture network propagation by the soundless cracking demolition agents (SCDAs) for in situ leaching, while the expansion pressure is within a few hundred MPa and the fracturing range is within a few meters [73]; thus, the permeability enhancement method by SCDA cannot meet the requirements of ISL. Yuan et al [10][11][12]74] proposed a blasting-enhanced permeability method in lowpermeability sandstone-type uranium deposits.…”

Section: Analysis Of the Isl Effect And Potential Enhanced Islmentioning

confidence: 99%

Mineral Composition and Full-Scale Pore Structure of Qianjiadian Sandstone-Type Uranium Deposits: Application for In Situ Leaching Mining

et al. 2022

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In situ leaching (ISL) is becoming the main mining practice for sandstone-type uranium deposits in China. The key to ISL technology is to aid the leaching solution in contacting the ore bed over a large range, which will induce a series of chemical reactions to extract uranium; thus, it is essential to thoroughly understand the reservoir physical properties of uranium deposits. Taking the Qianjiadian sandstone-type uranium deposits (southern Songliao Basin, China) as an example, the mineral composition and pore structure of samples in different layers were measured using X-ray diffraction (XRD), thin section analysis (TSA), low-temperature N2 adsorption (LTN2A), and mercury intrusion porosimetry (MIP), and their influences on the ISL effect were analyzed. The results show that more than 65% of the minerals in the Qianjiadian uranium deposits are felsic minerals, and the carbonate minerals, clay minerals, and augite are auxiliary minerals. The primary intergranular pores, intergranular-dissolved pores, intragranular-dissolved pores, intercrystalline pores, and microfractures are developed in uranium deposits with various lithologies to different degrees. The macropores ( >1000 nm) and mesopores (100-1000 nm) of medium sandstone, argillaceous sandstone, and siltstone are well developed; in contrast, the proportions of micropores ( <10 nm) and transition pores (10-100 nm) in coarse sandstone, fine sandstone, and sandy mudstone are quite high. The heterogeneity of pores in uranium deposits of different lithologies is strong and influences the mineral composition and its fabric mode. Coarse sandstone, fine sandstone, and sandy mudstone are favorable for ISL mining in Qianjiadian uranium deposits because their permeability is above the required permeability threshold of ISL. The uranium deposits with permeability below the threshold are recommended to adopt the blasting-enhanced permeability method to improve their permeability for achieving large-scale and high-efficiency ISL mining. This study can provide guidance for the selection of favorable ore beds for ISL mining and reservoir stimulation methods in low-permeability sandstone-type uranium deposits.

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“… 4 − 8 Among them, temperature is the key factor affecting the speed and peak pressure of static crushing agent, and many other studies have shown that the higher the temperature, the faster the peak pressure is reached, and the peak expansion pressure can be increased by increasing the pore size and suitable water agent ratio. 9 , 10 The peak expansion pressure can be increased by increasing the pore size and suitable water agent ratio. Some scholars focused on the improvement of temperature on the reaction efficiency of static breakers, indicating that the reaction rate can be changed by increasing the temperature.…”

Section: Introductionmentioning

confidence: 99%

“…Toshio Kono was the first to conduct theoretical research on expansion agents, pointing out that the magnitude of expansion pressure depends on the growth of Ca(OH) 2 crystals and finding that the ambient temperature and the thermal conductivity of the crushed material are the main factors affecting their growth . A large number of scholars at home and abroad have conducted a large number of experimental studies and found that the ratio of water agent, temperature, and pore size are the main factors affecting the expansion pressure of the static crushing agent. − Among them, temperature is the key factor affecting the speed and peak pressure of static crushing agent, and many other studies have shown that the higher the temperature, the faster the peak pressure is reached, and the peak expansion pressure can be increased by increasing the pore size and suitable water agent ratio. , The peak expansion pressure can be increased by increasing the pore size and suitable water agent ratio. Some scholars focused on the improvement of temperature on the reaction efficiency of static breakers, indicating that the reaction rate can be changed by increasing the temperature. , …”

Section: Introductionmentioning

confidence: 99%

Mechanistic Study of a Microwave Field-Controlled Static Crushing Agent for Efficient Rock Breaking

Liu

Guan

et al. 2022

ACS Omega

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The long reaction time and uncontrollable reaction process of the swelling agent in the process of rock breaking by static crushing agent lead to unsatisfactory efficiency and effect of rock breaking. This paper uses physical experiments to compare and analyze the changes in temperature and pressure of the hydration reaction under different microwave conditions; utilizes microscopic analysis of the hydration reaction products under each condition, combined with numerical calculations to elucidate the mechanism of the effect of microwave field on the hydration reaction of the expansion agent; and proposes a microwave field-controlled static crushing agent rock-breaking method. The study reached the following main conclusions: (1) microwave heating is better than conventional heating in terms of heating rate, peak temperature, and peak pressure; (2) using static crushing agent rock breaking is preferable to use a low-power microwave field to control the reaction process, and to ensure that the initial temperature is not higher than the local water boiling point; (3) microwave heating to promote the reaction mechanism lies in its deep heating of the system, faster heating rate, and higher energy utilization, and is more conducive to hydration expansion reaction; (4) selective heating of microwaves can enhance the hydration reaction of calcium oxide and inhibit the production of hydrated tricalcium silicate, making the reaction more complete, while microwave heating will also improve the microstructure of hydration products.

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The influence of borehole arrangement of soundless cracking demolition agents (SCDAs) on weakening the hard rock

Cited by 50 publications

References 37 publications

Numerical Simulation on Selection of Optimal Delay Time for Precise Delay Blasting

Numerical Simulation on Selection of Optimal Delay Time for Precise Delay Blasting

Mineral Composition and Full-Scale Pore Structure of Qianjiadian Sandstone-Type Uranium Deposits: Application for In Situ Leaching Mining

Mechanistic Study of a Microwave Field-Controlled Static Crushing Agent for Efficient Rock Breaking

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