Abstract To liberate magnetite from ludwigite, the dielectric properties of ludwigite are investigated by cavity perturbation method at 2.45 GHz from 20 to 800 °C. The results show dielectric properties of ludwigite with temperature can be divided into three stages: at the first stage (20–200 °C), the dielectric constant (ε′), dielectric loss factor (ε″) and loss tangent (tan δ) increase approximately by 4.55, 47.31 and 38.89%, respectively, at the second stage (200–500 °C), ε′ increases slowly by 5.19%, while ε″ and tan δ gradually decrease, at the third stage (500–800 °C), ε′ first increases rapidly by 6.21% at 500–700 °C and then increases slowly beyond 700 °C, ε″ and tan δ fluctuate slightly. Meanwhile, the penetration depth (Dp) decreases significantly at 20–200 °C and decreases slightly at 200–500 °C, but decreases substantially again at 500–700 °C, and finally is closed to the constant value beyond 700 °C. The heating rate of magnetite is faster than those of ascharite and serpentine, which results in the formation of intergranular fractures to promote the liberation of magnetite from ludwigite by microwave heating.

中文翻译：

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路德维特高温介电性能及其对微波加热过程的影响

摘要 为了将磁铁矿从路德维石中解放出来，采用腔微扰法在20~800 °C、2.45 GHz下研究了路德维特的介电性能。结果表明，铝矾土的介电性能随温度可分为三个阶段：第一阶段（20-200°C），介电常数（ε'）、介电损耗因子（ε″）和损耗角正切（tanδ）分别增加约 4.55、47.31 和 38.89%，在第二阶段（200-500°C），ε′缓慢增加 5.19%，而 ε″和 tanδ 逐渐减小，在第三阶段（500-800°C） C)，ε'在 500-700 °C 时先快速增加 6.21%，然后在 700 °C 后缓慢增加，ε" 和 tan δ 略有波动。同时，穿透深度 (Dp) 在 20-200 °C 时显着降低，在 200-500 °C 时略有下降，但在 500-700°C 时再次大幅下降，最终在 700°C 后接近恒定值。磁铁矿的加热速度比石柱石和蛇纹石的加热速度快，从而形成晶间裂缝，促进了磁铁矿通过微波加热从路德维石中解放出来。