| 摘要 |
<p>A process for producing steel comprises desulphurizing pig iron under reducing conditions and in the presence of nitrogen to a sulphur content below 0.013 per cent and refining the desulphurized pig by blowing with a gas containing oxygen and nitrogen until at least 80 per cent of the carbon is removed, and voluminous carbon monoxide produced to remove nitrogen and maintain the sulphur content of the final steel at less than 0.013 per cent. The desulphurizing process may comprise blowing with nitrogen in the presence of a desulphurizing agent and the refining is preferably performed by surface blowing with a gas containing at least 96 per cent oxygen at a pressure of 50-175 p.s.i. gauge, to a carbon content of less than 0.10 per cent. If scrap is used during the refining process the sulphur content thereof should be suitably low, preferably below 0.013 per cent. The slag should have a lime/silica ratio of 2 to 3.5 to 1, the total lime plus silica being equal to at least 50 per cent and FeO plus MnO between 25 and 40 per cent. Specification 609,850 is referred to.</p> |
