Goethite (FeOOH)-based ore has become attractive to be utilized in ironmaking. As mildly dehydrated to remove its high combined water (CW), it changes to a nanoporous hematite ore. The nanopore contributes a significant increase in ore reduction reactivity due to the nanocontact between iron oxide and reducing agents such as C, CO, or H₂. However, the long dehydration time of goethite ore is still one problem. This study revealed the effect of vacuum condition on the mild-dehydration of goethite-based ore significantly reduces the ore dehydration time. The dehydration is finished within one hour at 300°C under high-vacuum condition (P=1.7 Pa), producing nanoporous hematite ore that is similar to under atmospheric one for 24 h. However, no significant decrease in the dehydration temperature under the high-vacuum condition. In contrast, in-situ heating TEM observation reveals that nanopore generation can occur at low temperatures under ultra-high vacuum conditions (P = 5.6×10^-6 Pa). Slit pore generates at low temperatures that then eventually disappear by merging to bigger pores at the higher temperatures.

基于针铁矿（FeOOH）的矿石已变得有吸引力，可用于炼铁。经过轻度脱水以除去其高结合水（CW），它变成了纳米孔赤铁矿矿石。由于氧化铁与还原剂（例如C，CO或H _2）之间的纳米接触，纳米孔显着提高了矿石还原反应性。。然而，针铁矿矿石的长时间脱水仍然是一个问题。这项研究表明真空条件对针铁矿基矿石的轻度脱水的影响显着减少了矿石的脱水时间。在高真空条件下（P = 1.7 Pa），在300°C下在一小时内完成脱水，生成与大气压下相似的纳米孔赤铁矿矿石24小时。但是，在高真空条件下脱水温度没有明显降低。相比之下，原位加热TEM观察表明，在超高真空条件下（P = 5.6×10 ^-6 Pa），纳米孔的产生可以在低温下发生。狭缝孔在低温下产生，然后通过在较高温度下合并成较大的孔而最终消失。