稀土精矿冶炼炉窑的高温烟气资源化利用研究

Research of resource utilization of high-temperature flue-gas of smelting furnace for rare earth concentrate

稀土精矿冶炼炉窑是稀土生产工艺的核心装备,会产生大量含氟酸性高温烟气,其中氟化物0.81%、硫酸雾1.06%、二氧化硫0.23%,同时温度达300℃以上,烟气余热丰富,烟气成分的复杂性和特殊性为余热及资源回收利用带来挑战。介绍一种新的稀土精矿冶炼炉窑的高温烟气余热利用技术及其现场中试情况。根据物质流、能量流守恒计算了烟气流量、温度、组分浓度以及余热量,分析了余热回收的可行性和技术难点;提出了新的烟气干法余热回收工艺,依据能源梯级利用原则,通过余热锅炉实现烟气分级降温和余热回收,同时回收高浓度冷凝酸并副产余热蒸汽;该工艺在稀土精矿冶炼炉窑系统进行了现场中试,采集并分析72 h中试数据,取得良好资源回收效果。

The smelting furnace of rare earth concentrate is the main equipment of rare earth production. A large number of acidic high-temperature flue gas will be produced, containing 0.81% fluoride, 1.06% sulfuric acid fog, and 0.23% sulfur dioxide, and its temperature is up to 300 ℃, that the waste heat could be utilized. But the complexity and particularity of the flue gas compositions bring great challenges to the recovery of heat and resource. A new waste heat utilization technology of high-temperature flue gas of rare earth concentrate smelting furnace was proposed, and the real situation of the field pilot-scale test was introduced. Firstly, the flue gas flow rate, temperature, component concentration and waste heat were calculated according to the conservation of material and energy. The feasibility and technical difficulties of the waste heat recovery were analyzed. Then, a new dry process of waste heat recovery of the flue gas was proposed. According to the cascade utilization principle of energy, the flue gas was grading cooled and the waste heat was used with the waste heat boiler. Moreover, high concentration condensed acid was gathered and the steam was produced by side. Finally, the field pilot-scale test of the new technology was demonstrated, and the data of 72 h were collected and analyzed. The field pilot-scale test showed a good effect on resource recovery.