The bottom you blow or production method null of the high containing nitrogen steel with the raised bottom blowing

摘要

PURPOSE:To stably produce a high nitrogen steel at a low cost by throwing specific amounts of coke into a molten steel at the point of time when C content in the molten slag reaches a specific value in a top and bottom blown converter, recovering an unburnt exhaust gas, and then bottom-blowing the prescribed amounts of N2 gas. CONSTITUTION:In a bottom blown or top and bottom blown converter for steel making, coke is thrown into a molten steel by 6-8kg/ch.t when C content in the molten steel reaches 1.0-0.3wt.%. Subsequently, at the point of time when the recovery of an unburnt exhaust gas in the converter is completed, an N2 gas in the amount corresponding to the amount of burnt lime used for refining is blown through tuyeres in the bottom. By this method, the steel with =60ppm nitrogen content can stably be obtained at a low cost without using a manganese nitride ferroalloy.