EUROPEAN STEEL TECHNOLOGY AND APPLICATION DAYS 2017 - ESTAD 2017

The SMS group vacuum converter technology combines the advantages of the AOD converter and the VOD technologies. In the vacuum converter process, the final decarburization step of stainless steel grades and ferroalloys takes place under vacuum. The dilution of oxygen by inert gases known from the AOD process is largely omitted. Use of SMS group´s vacuum converter technology ensures the reproducible achievement of ultra-low carbon, nitrogen, and hydrogen contents in the production of stainless steel. The product portfolio for high-chromium steel grades can be expanded accordingly. For stainless, acid- and heat-resistant steel grades requiring low final carbon and nitrogen contents, the production costs are significantly reduced mainly by lower consumptions of argon and reduction material. The process time can be strongly shortened compared to standard AOD operation. The vacuum converter technology is also suitable for production of duplex steel grades with high nitrogen contents. Following the decarburization down to lowest carbon contents under vacuum the nitrification process is carried out under atmospheric conditions in the converter. Applying much higher nitrogen blowing rates by bottom tuyères compared to typical lancing used in secondary ladle metallurgy the process time can be largely reduced. SMS group´s vacuum converter technology stands for cost effective production of medium and low carbon ferroalloys. Due to refining under vacuum conditions even the production of low carbon FeCr is possible in the converter. Depending on the target carbon contents expensive argon is partly or fully replaced with CO2. In the chemical industries, many processes generate carbon dioxide as a waste product, explaining the low price of the gas in comparison to argon. The entire process engineering ensures lowest operating costs. Used as a reaction gas, CO2 has a strong cooling effect in decarburization. The addition of costly solid metallic coolants can be significantly reduced when treating ferrochrome and ferromanganese leading to higher productivity as well as reduced processing costs. The presentation introduces the vacuum converter technology and its benefits.