住友金属工业公司开发出熔炼高纯度低碳钢或低硫钢的“RH（真空脱气装置）粉末顶吹精炼法”。在真空脱气装置的上部插入水冷吹管，利用粉末顶吹精炼法能除去通常真空脱气较难去除的钢液中的硫或碳等杂质。在和歌山制铁所第二炼钢厂的160吨级RH上已设置试验设备，集中用于熔炼高 Sumitomo Metal Industries has developed “RH (Vacuum Degasser) Powder Top-blowing Refining Method” for smelting high-purity mild steel or low-sulfur steel. A water-cooled blow pipe is inserted in the upper part of the vacuum degassing apparatus, and impurities such as sulfur and carbon in the molten steel, which is generally difficult to remove by vacuum degassing, can be removed by the powder top blowing refining method. A test facility has been set up on the 160-tonne RH at the second steelworks at Wakayama Iron Works, focusing on smelting high