Tian Yu, Xu Yanhui, Guan Weihua, Zheng Qiyuan, Dai Yufei, Ma Shengfeng, Li Yu
State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization, Baotou Research Institute of Rare Earths, Inner Mongolia, Baotou 014030, China.
College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, China.
ACS Omega. 2021 Oct 13;6(42):28119-28130. doi: 10.1021/acsomega.1c04194. eCollection 2021 Oct 26.
This article introduces an efficient decomposition process that uses sodium carbonate (NaCO) and activated carbon (C) as additives to decompose Bayan Obo mixed rare earth concentrate (hereinafter to be referred to as RE concentrate) by nonoxidative microwave radiation roasting. The roasting temperature, holding time, and contents of NaCO and activated carbon are investigated. The optimum process parameters for decomposition are 800 °C and 30 min. The ratio of m(NaCO)/m(RE concentrate) is 0.5, and the ratio of m(C)/m (ER concentrate and NaCO) is 0.2 based on experimental data. Under the above conditions, the decomposition rate (shortened to DR) of RE concentrate is 98.58%, and the removal rates (shortened to CRs) of fluorine (F) and phosphorus (P) reached 80.35 and 46.75%, respectively. These rates are higher than traditional oxidation roasting under the same conditions. The three reasons for the result are the unique microwave heating characteristics, the overall efficient reaction of the mixture (RE concentrate, NaCO, and activated carbon), and the high nonoxidation rate of cerium. For these reasons and large experimental data, the reaction rate of the mixture is improved, and the efficiency of dilute hydrochloric acid for leaching rare earth elements is enhanced. In this article, the valence of rare earth elements in the roasted ore is all in the form of trivalence. Importantly, this nonoxidative roasted product can avoid the generation of chlorine in hydrochloric acid leaching. Moreover, such a short holding time is scarce in traditional roasting. When the mixture was roasted by utilizing microwave heating, the sinter phenomenon of the roasted product was avoided at high-temperature roasting. Finally, the surface morphology of RE concentrate at different conditions was observed by scanning electron microscopy (SEM) analysis, which can be used to compare the specific differences of roasting methods. According to these results, this process is beneficial for the decomposition of RE concentrate in terms of NaCO roasting and is helpful for improving the clean and green technology method of hydrometallurgy.
本文介绍了一种高效的分解工艺，该工艺使用碳酸钠（NaCO）和活性炭（C）作为添加剂，通过非氧化微波辐射焙烧分解白云鄂博混合稀土精矿（以下简称稀土精矿）。研究了焙烧温度、保温时间以及碳酸钠和活性炭的含量。分解的最佳工艺参数为800℃和30分钟。根据实验数据，m(NaCO)/m(稀土精矿)的比例为0.5，m(C)/m(稀土精矿和NaCO)的比例为0.2。在上述条件下，稀土精矿的分解率（简称为DR）为98.58%，氟（F）和磷（P）的去除率（简称为CRs）分别达到80.35%和46.75%。这些率高于相同条件下的传统氧化焙烧。结果产生的三个原因是独特的微波加热特性、混合物（稀土精矿、NaCO和活性炭）的整体高效反应以及铈的高非氧化率。由于这些原因和大量实验数据，混合物的反应速率得到提高，稀盐酸浸出稀土元素的效率得到增强。在本文中，焙烧矿中稀土元素的价态均为三价形式。重要的是，这种非氧化焙烧产物可避免盐酸浸出中氯的产生。此外，如此短的保温时间在传统焙烧中很少见。当利用微波加热焙烧混合物时，避免了高温焙烧时焙烧产物的烧结现象。最后，通过扫描电子显微镜（SEM）分析观察了不同条件下稀土精矿的表面形态，可用于比较焙烧方法的具体差异。根据这些结果，该工艺在碳酸钠焙烧方面有利于稀土精矿的分解，有助于改进湿法冶金的清洁绿色技术方法。
