The RH plant of Big River Steel is part of the steelmaking shop consisting of a DC electric arc furnace with a gas cleaning plant and an RH degasser.
Vacuum is generated by a steam ejector vacuum pump. A steam boiler system supplies the required amount of steam to the six ejectors. A TOP lance system is installed to blow oxygen for forced decarburization or chemical heating during vacuum treatment, or to burn gas with oxygen to keep the vessel refractory material at operating temperature during non-vacuum treatment.
A special feature of this RH unit is the vacuum alloy addition system, which consists of a vacuum lock system and three vacuum scale hoppers. This arrangement allows electrical steel grades with Si-contents of up to three percent to be produced in less than 50 minutes cycle time.
The measuring and control equipment takes care of monitoring, controlling and regulating all process sequences. There is not only a basic automation system but also a process computer. This provides heat and process related information, collects data for a heat report, tracks and monitors the physical-chemical state of the heat, and finally determines set point data for the types and amounts of additions as well as for the duration of time-dependent treatment steps.