Antimony is often used as a hardener for alloys. There are few studies on the preparation of antimony from Sb₂O₃ by microwave carbothermal reduction. In this study, Sb₂O₃ was used as the raw material, and the resonant cavity perturbation method was used to select anthracite as the reducing agent according to the microwave absorption of the material mixture. The single-factor experiment of reduction temperature, reduction time, and reducing agent ratio was carried out in a microwave tube furnace. The process parameters were optimized by response surface methodology (RSM). Under the optimized conditions, the reduction temperature was 758 °C, the reduction time was 56 min, the reducing agent addition ratio was 0.123, and the molten salt addition ratio was 0.1. An antimony ingot with a yield of 92.19% and a purity of 99.45% was obtained. The products and residue of the antimony ingot were analyzed by X-ray diffraction analysis (XRD), X-ray fluorescence (XRF), thermogravimetric (TG) analysis, scanning electron microscopy (SEM), and the mechanism of carbothermal reduction of antimony oxide powder in a microwave field was studied. The results showed that the microwave carbothermal reduction process of Sb₂O₃ under a microwave field had three stages: 25~655 °C, 655~850 °C, and >850 °C. Different stages changed with temperature. This green and energy-saving microwave heating technology can provide a feasible method for the efficient preparation of antimony.

Graphical Abstract

中文翻译：

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微波场氧化锑粉碳热还原制备金属锑：机理与过程

锑通常用作合金的硬化剂。关于微波碳热还原Sb ₂ O ₃制备锑的研究较少。本研究以Sb ₂ O ₃为原料，根据物料混合物的微波吸收情况，采用谐振腔微扰法选择无烟煤作为还原剂。在微波管式炉中进行还原温度、还原时间和还原剂配比的单因素实验。通过响应面法（RSM）优化工艺参数。优化条件下，还原温度为758 ℃，还原时间为56 min，还原剂添加比例为0.123，熔盐添加比例为0.1。得到锑锭，收率92.19%，纯度99.45%。通过X射线衍射分析(XRD)、X射线荧光分析(XRF)、热重分析(TG)、扫描电子显微镜(SEM)对锑锭的产物和残渣进行分析，并对氧化锑的碳热还原机理进行了分析。研究了微波场中的粉末。结果表明，微波场下Sb ₂ O ₃的微波碳热还原过程经历了3个阶段：25~655 ℃、655~850 ℃和>850 ℃。不同阶段随温度变化。这种绿色节能的微波加热技术可为锑的高效制备提供可行的方法。

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