| 摘要 |
PURPOSE:To obtain low copper steel at a low cost, by prescribing S content in molten iron to >= a fixed value, adding Na2S and Na2SO4 simultaneously to copper-contg. molten iron to remove copper and also C, Si, P, etc. in molten iron while suppressing vaporization of Na. CONSTITUTION:Mixture of prescribed ratio of dewatered Na2S and Na2SO4 is brought into contact with molten pig iron, to obtain molten steel by decarburizing C in molten iron, and to convert copper to sulfide and transfer it into molten slag. The molten steel and slag are separated, molten steel is desulfurized, and water is added to molten slag to obtain aq. soln. S1 and a ppt. P. The ppt. P is put in sulfuric acid aq. soln. to obtain aq. soln. of a prescribed pH, and aq. soln. and ppt. of copper sulfide main body are separated, CaCO3 and CaO, or NaOH are added to the aq. soln. to obtain aq. soln. of a prescribed pH, and an aq. soln. S2 and ppt. of (gypsum and) iron hydroxide main body are separated. On the other hand, quick lime or slaked lime is added to the soln. S1, SiO2, P2O5 are mainly pptd. as Ca salt, and it is filtered. Obtd. aq. soln. and the soln. S2 are neutralized by sulfuric acid, then, vaporized and dried up, to obtain reusable dried up material composed mainly of Na2S and Na2SO4. |
