The reduction process inside the ore pre-reduction rotary kiln involves a series of physicochemical reactions, and in-depth understanding of the reduction behavior is helpful to improve the product quality and productivity. This paper reports a three-dimensional steady state mathematical model based on computational fluid dynamics, which considers heat transfer, mass transfer and chemical reactions inside the rotary kiln. A user-defined functions (UDFs) program in C language is developed to define physical parameters and chemical reactions, and calculate the heat and mass transfer between freeboard and bed regions. The model is validated by measurement data and is then used to investigate the detailed information inside the rotary kiln. The results show that there is a temperature gradient in the bed, which is maximal near the kiln tail and decreases gradually as the reduction process progresses. The result also confirms that the reduction of FeO to Fe is the limiting step of the whole reduction process because this reaction requires a higher reduction potential. Furthermore, the influence of C/O mole ratio and fill degree are analyzed by comparing the average bed temperature, reduction potential and metallization ratio.

中文翻译：

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预还原回转窑内还原过程特性的数值分析

矿石预还原回转窑内的还原过程涉及一系列物理化学反应，深入了解还原行为有助于提高产品质量和生产率。本文报道了一种基于计算流体动力学的三维稳态数学模型，该模型考虑了回转窑内的传热、传质和化学反应。开发了一个C语言用户定义函数(UDFs)程序来定义物理参数和化学反应，并计算干舷和床区之间的传热和传质。该模型通过测量数据进行验证，然后用于调查回转窑内部的详细信息。结果表明床层存在温度梯度，在窑尾附近最大，随着还原过程的进行逐渐减小。结果还证实，FeO 还原为 Fe 是整个还原过程的限制步骤，因为该反应需要更高的还原电位。此外，通过比较平均床温、还原电位和金属化率，分析了C/O摩尔比和填充度的影响。