BOF Bottom Stirring, also referred to as as combined blowing) involves the the introduction of small amount of inert gas from the furnace bottom and is regarded as one of the major innovations for the process.  The injected gas provides mild stirring of the bath during and after top blowing with oxygen and promotes a desirable carbon-oxygen equilibrium in the bath and slag. Bottom stirring improves BOF yield (reduced slag formation), reduces oxygen and flux consumption, and increases vessel life. It also improves product quality - by allowing lower oxygen and carbon content. Some BOF converters have more have more advanced injection systems where oxygen, flux and other gases are injected from the bottom of the converter.  

Industry experts state that maintaining effective stirring continues to be a major inconvenience in many shops that have tried the technique. Nevertheless, this technique is regarded to have a high applicaiton potential for China, India and the US.