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<p>Microwave irradiation combined with mechanical rock breaking is a new approach to mining that has great potential. To elucidate the operating parameters required to control and optimize the microwave–mechanical mining process, it is necessary to study the microwave cracking of ore in situ. Therefore, in this paper, field tests were carried out in the Sishanling Iron Mine. In these tests, a home-made, high-power microwave-assisted fracturing system was adopted to crack iron-containing rocks of different grades. Various aspects of the microwave–ore interactions were studied including the microwave reflection characteristics, temperature rise generated, and degree of cracking generated in different grades of ore. The results indicate that the impedance regulating system incorporated into the apparatus can quickly (&lt; 5&#xa0;s) and automatically adjust the standing wave ratio of the microwaves to below the threshold value, even when the grade of the ore changes. Irrespective of the grade of the ore, the microwaves had smaller reflection coefficients and produced better heating effects when a right-angled microwave antenna was used and the working distance was 5&#xa0;cm. The smallest peak standing wave ratios and volatilities were encountered when medium-grade ore was treated (compared to the two other grades considered). As the grade of the ore increased, the heating effect produced in the ore (i.e. average temperature at the center of the irradiation zone, area of the high-temperature zone, and temperature gradient) was found to increase at first and then decrease. At the same time, the microwave-induced cracking effect in the ore (damage area, damage depth, and crack width) also increased at first and then decreased. Using a right-angled antenna, microwave power of 60&#xa0;kW, working distance of 5&#xa0;cm, and microwave-irradiation time of 40&#xa0;s, the fracture zones generated in medium and high-grade ore covered areas of approximately 46&#xa0;cm × 43&#xa0;cm and 38&#xa0;cm × 30&#xa0;cm, respectively. The corresponding damage depths were 60&#xa0;cm and 50&#xa0;cm, respectively. A discussion was also given of the influence that the onsite primary fractures and grade of the ore has on the microwave-induced fracturing effect.</p>

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Field Tests Using High-Power Microwaves to Crack Iron Ore of Different Grades

  • 期刊论文

  • 发表日期：

    2025年6月23日

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  • Feng Lin,
  • Xia-Ting Feng,
  • Shi-Ping Li,
  • Tian-Yang Tong,
  • Yun-Tan Ao,
  • Yu-Xi Liu

摘要

Microwave irradiation combined with mechanical rock breaking is a new approach to mining that has great potential. To elucidate the operating parameters required to control and optimize the microwave–mechanical mining process, it is necessary to study the microwave cracking of ore in situ. Therefore, in this paper, field tests were carried out in the Sishanling Iron Mine. In these tests, a home-made, high-power microwave-assisted fracturing system was adopted to crack iron-containing rocks of different grades. Various aspects of the microwave–ore interactions were studied including the microwave reflection characteristics, temperature rise generated, and degree of cracking generated in different grades of ore. The results indicate that the impedance regulating system incorporated into the apparatus can quickly (< 5 s) and automatically adjust the standing wave ratio of the microwaves to below the threshold value, even when the grade of the ore changes. Irrespective of the grade of the ore, the microwaves had smaller reflection coefficients and produced better heating effects when a right-angled microwave antenna was used and the working distance was 5 cm. The smallest peak standing wave ratios and volatilities were encountered when medium-grade ore was treated (compared to the two other grades considered). As the grade of the ore increased, the heating effect produced in the ore (i.e. average temperature at the center of the irradiation zone, area of the high-temperature zone, and temperature gradient) was found to increase at first and then decrease. At the same time, the microwave-induced cracking effect in the ore (damage area, damage depth, and crack width) also increased at first and then decreased. Using a right-angled antenna, microwave power of 60 kW, working distance of 5 cm, and microwave-irradiation time of 40 s, the fracture zones generated in medium and high-grade ore covered areas of approximately 46 cm × 43 cm and 38 cm × 30 cm, respectively. The corresponding damage depths were 60 cm and 50 cm, respectively. A discussion was also given of the influence that the onsite primary fractures and grade of the ore has on the microwave-induced fracturing effect.