Patented Nov. 24, 1942 2,303,064

d’UNlTED ‘STATES PATENTOFFICE .

- ' ' ' aaoaoei ' ‘ l . PROCESS FOR- SIMULTANEOUSLY DEPHOS PHORIZING ANDDEOXIDIZING STEEL René Perrln, Paris, France, assignor to Societe d'Electro-Chimie, dlElectro-Metallurgie ct ?ea Acieries Electriques d’Ugine, Paris, France, a corporation of France ‘ No Drawing. Application June 22, 1940, Serial No. 341,967. In France June_'_23, 1939 ' 3 Claims. (Cl. 75-46) This invention relates to a method for the si necessary to use an addition of manganese in multaneous dephosphorization and deoxidization metallic or alloy form. ' of steel. ‘ _ The said method consists in treating the phos The chief object of the invention is to provide phorous steel with a basic slag rich in MnO and a method for obtaining in one and the same op— Ca which may contain also iron oxide as well as eration steels possessing low contents of phos other elements such as ?uidifying agents, by phorus and of oxygen, manganese being at the bringing into play a quantity of slag suf?cient same time introduced into the steel. The said to cause the proportion of P205 in the ?nal slag to method is more especially applicable to the manu be comparatively low, such as, for example, of facture of steel in a basic converter. 10 the order of 5%, the ‘ratio between the man It is well known that it is comparatively easy ganese oxide and iron oxide contents ‘of the ?nal to obtain a steel with a low phosphorus content slag being-the higher, the higher is the intended in a Thomas converter without having to take par ?nal manganese content of the steel. ticular precautions, but this result is often ob In carrying out the method according to the tained only at the cost of an overoxidation of the invention, the initial MnO content of the slag metal. Furthermore, it is well known that if used for treating the steel will be the higher, all manganese is introduced into the metal in such other things being the same, the higher is the a converter at the end of the process, a consider quantity of manganese to be introduced into the able re-introduction of phosphorus is produced metal. The quantity of slag to be used is in due to the reduction by the manganese of some creased as the dephosphorization to be obtained phosphorous compound of the slag remaining and the amount of manganese to be introduced in the apparatus or in the walls impregnated with into the steel is increased. P205. In order to do awaywith this drawback Practically, if it is intended to obtain a rather it is possible, as applicant'has proposed in his high ?nal manganese content, for instance 0.3%, French Patent No. 843,029 of February 5, 1938, to the ratio MnO/FeO will be taken equal to or introduce into the apparatus simultaneously with higher than 1. v ' the manganese a slag containing a proportion of The treatment will be effected preferably by _MnO su?icient for preventing the said reduction one of the known methods of violent intermixing of phosphoric acid or other phosphorous com between molten steel and slag, either by rapidly pounds. ‘ pouring the steel in thick jet from considerable The applicant has already proposed, in another I height, say four to six meters, on to the slag or connection, a method for manufacturing steels by a gaseous intermixing caused by an energetic having a low phosphorus content without leading blowing operation in a receptacle, or by a gaseous simultaneously to a. prohibitive oxygen content intermixing caused by a gaseous escape due 'to and even while causing ‘a certain deoxidation. Z the reaction of puri?cation itself which is more This method essentially consists in treating the particularly the case when a high carbon steel oxidized steel by means of a basic non-oxidizing is treated. slag, thereby ‘using the iron oxide dissolved in The slag which is-used can be introduced into the metal for oxidizing the phosphorus and caus the ladle or apparatus in which the reaction is ing the so formed phosphoric acid to be absorbed 40 effected either in the molten state; which is gen by the lime which is presentdin the slag. But this erally very advantageous, or in the solid state, method is applicable only to highly oxidized steels more particularly when the quantity of slag to and the amount of phosphorus which can be be used is comparatively low with respect to the removed is limited by the quantity of the oxidiz quantity of metal to be treated, or when the metal ing elemental. e. the'iron oxide dissolved in the 45 contains an excesso! heat su?lcient for melting metal. This quantity of dissolved iron oxide is the slag. In these latter cases it will be possible always less than the amount which would be re to introduce either a previously formed slag or quired to saturate the steel with iron oxide.» the constituents of this slag in the preheated or non-preheated state. ‘ The method which forms the subject of the 50 present invention has for its purpose to produce The method according to the invention offers a dephosphorization of the steel irrespective of the the above mentioned advantage‘ of producing a degree of oxidation of the latter with a simul dephosphorization of the steel while deoxidizing it taneous introduction of manganese into the steel in a very substantial manner. Furthermore, it and a concomitant deoxidation, without it being 55 allows a re-introduction of manganese in the 2 . 2,808,064 metal, thus dispensing with any addition oi metal The analysis of ‘the ?nal slag was approxi lic manganese. In the case where the steel is mately the following: manufactured and heated according to the in Percent vention in a Thomas converter, this re-introduc 9 tion of manganese can be effected without any .5 lunezo 7.5 tear of re_-phosphorization. For this Purpose it CaO 62 is sufilcient, alter a first normal blowing oper ation having lowered the phosphorus content to 810: a > ‘ 6 0.05%, for example, to slag out the converter and m p ' ' 2.5 ' to introduce the slag according to the invention What I claim 'is:. (basic slag rich in MnO) in the converter as a l. A method for the simultaneous dephosphori second slag. After a very short further blowing cation and ,deoxidization of- steel in a Thomas designed for establishing the equilibrium between‘ converter with concomitant introduction of man the metal and the slag, the phosphorus content ganese, which consists in eiiecting a normal blow will be lowered to the desired value and, simul is ing operation in order to lower the phosphorus taneously, the metal will have received the neces "content oi’ the steel to a value of the order of sary addition of manganese owing to a reduction ' 0.05%, in slagging oil. then in introducing in the .of the M110 of the slag: It will thus be ready for converter onto the steel a quantity of a basic casting without any direct‘ addition of manganese slag rich in manganese oxide which is su?icient having been necessary. for causing the proportion oi’ P20. in the ?nal In addition to the above mentioned advantages. slag to be not over about 5% and in eil'ecting a ‘which oiier a considerable simpli?cation more very short'iurther blowing in order to establish particularly in the Thomas process and especially equilibrium between metal and slag. when it is desired to obtain a high grade metal 2. A method for the simultaneous dephosphori from Thomas steel, the method oiiers in'all cases nation ‘and deoxidation oi steel in a Thomas con ‘the considerable advantage 0! not requiring the verter with concomitant introduction of man use of metallic manganese. It permits using ganese, which consists in eil'ecting a normal blow manganese ore instead oi term-manganese and ing operation in order to lower the phosphorus thus does away with the necessity of ‘specially content of the steel to a value oi’ the order of manufacturing this latter alloy, thereby e?ecting 30 ‘0.05%, in slagging o?, then in adding to the steel ~ considerable saving in cost. a quantity of a basic slag rich in manganese oxide Example: A Thomas steel of the following anal which is su?lclent for causing the proportion of ysis: C=0.05%; Mn=0.08%; P—__—0.05% and pos PsOs in the ?nal slag to be not over about 5% and sessing an oxygen content of 0.060% has been in vigorously mixing the steel with the slag in violently intermixed with 4% by weight of a slag 35 order to establish equilibrium between steel and _oi the iollowing analysis. ‘ slag. , 3. A method for the simultaneous dephosphorié Percent zation and deoxidation or steel in 9. Thomas con FeO 10 verter with concomitant introduction of man mo 15 ganese which consists in manufacturing a bath 08.0 _ M " ' 60 of steel the content of which in phosphorus is S10: ‘ 5 not over aboutv0.05%, in a Thomas converter, rapidly pouring the said bath without the slag the remainder being iormed of ?uidiiying agents formed in the converter onto a quantity 0! a basic and more particularly by ?uor-spar. 45 slag rich in manganese oxide which is sumcient After treatment the steel had the following - for causing the proportion ‘of PsOs in the ?nal

analysis: ‘ _ slag to be not over about 5% and separating the C==0.05%; Mn=0.8%; P==0.012% and showed so treated steel from the slag. an oxygen content oi 0.030%. _ RENE PERRlN. ' ' CERTIFICATE'OF‘ CORRECTION._ _ _ _' " _ y

- : ‘ ' ' ’ Hm'rember 21+, 1%2. I RENE PERBIN; ~' ' ' I ’

I " It‘ is hereby. 'certi'fied that e'rror é-ppea'ra‘in the printed‘ specification of the above numbered iqatent'requiring oorrection 9:3 follows: Page'Z, sec. 0nd column, line 19, claim 1, after "oxide" insert —-'_, said slag having a' ratio of manganese oxide ‘to ‘iron 'oxide at. vleast equal to l,'--—;' and thet the said Letters ‘Patent shoilld be readywith this correction therein that the same .miiy 'confo'm to the record of the'case in the Patent Office. Signed and sealed‘ this‘ 12th ‘dajr of January, A. n. ,19Lp5.

Henry Van Arsdale, (Seal) _ Acting Commissioner of Patents.