A method of making steel in a vessel comprising providing a lance for blowing oxygen on the surface of the steel in the vessel, the lance joined to a lance carriage and in communication with an accelerometer, the accelerometer in signal communication with a data acquisition module and a computer; charging the vessel with materials for steel making; lowering the lance into the vessel and injecting oxygen into the materials; acquiring a signal from the accelerometer indicative of lance vibration; processing the vibration signal to determine component frequencies of lance vibration; comparing the levels of the component frequencies to desired operating values; and adjusting at least one steel making process parameter based on the level of at least one of the component frequencies. The steel making process parameter to be adjusted may be oxygen flow rate through the lance.