US1081403A - Method for removing sulfur from cast-iron. - Google Patents

Description

WALTER F. PRINCE, OF ELIZABETH, NEW JERSEY.

METHOD FOR REMOVING SULFUR FROM CAST-IRON.

No Drawing.

To all whom it may concern:

Be it known that I, \VAL'rsn F. PRINCE,

a citizen of the United States, residing at Elizabeth, county of Union, and State of New Jersey, have invented certain new and useful Improvements in Methods for Removing Sulfur from Cast-Iron, of which the following is a full, clear, and exact description.

My invention pertains to the removal of sulfur from cast iron.

It is a matter of common knowledge that sulfur is one of the most detrimental elements in making cast iron that is met with in the foundry. Ordinary ig iron is roughly estimated to contain tie following amounts: in number one pi .08; in number two pig, about .04 or .05; in number three pi", .06 and so on. \Vhen this iron is graded it IS sold as to its grade, and the price varies with the varying amount of sulfur which it contains. -When this iron containing say, .04, goes into the cupola and is melted it picks up more sulfur from the fuel in the cupola and issues therefrom containing about .07, .08 and as high as .1. This is especially true when mineral fuel is used, as it is difiicult to prevent the metal from taking up sulfur. It is well known also that excess of sulfur in cast iron devel- 80 o s a multiplicity of micro-sulfur flaws tli erein and when this excessive amount of sulfur is )resent the cast iron resents a honey-com d appearance. The eleterious effects of these treacherous sulfur areas, as well as other microscopic (laws, with their prolonged ramifications spreading along the ultimate crystals of the metal and thereby destroying metallic cohesion, is a matter that is of grave consequence. Constant vibration ultimately loosens the metallic adherence of the crystals of the metal, especially in areas where these micro-flaws of sulfur exist. (lankering by internal corrosion and disintegration is induced whene er the ter minations of the sulfid areas or other flaws in any way become exposed at the surface of the metal, either to the action of atmospheric or other oxidizing influences. In many other ways it can also be observed how injurious these sulfid flaws are in cast iron.

At present about 00% of good castings are obtained to the amount of iron melted. Consequently 40% of the castings has to go back to the on ola each day which has picked up enoug l sulfur to make this scrap carry .07 or .08 in sulfur. When this goes Specification of Letters Patent.

Application filed May 8, 191.2. Serial No. 696,019.

Patented Dec. 16, 1913.

back additional sulfur is picked up, and for this reason it is absolutely necessary to use pig iron as low in sulfur as possible which, of course, is quite expensive.

The present invention relates to a novel, cheap, and etiicient method of removing this sulfur from the melted cast iron; or at least; so much thereof as may be deemed necessary or desirable.

In the old Bessemer process melted iron is put into a converter, air blown through the metal until all the silicon, manganese, and carbons are burnt out, the whole reduced to a pure metallic iron, and then sullicient quantities of each were put back to make the grade of steel desired. While my process is somewhat similar, in some respects, to the Bessemer process, at the same time it is radically diflerent therefrom in other respects. In my method melted iron, known as gray or foundry cast iron or malleable iron, is taken from the cupola or furnace and put into a ladle or reservoir either directly or by the aid of other instrnmentalities. Air,

as, steam, or some other oxidizin agent is lown through openings in the sides or the bottom of the ladle into and through the molten metal. As the said air, gas or steam or other equivalent comes into contact with the molten metal it oxidizes the manganese creating manganese oxid, which, owm to its allinity therefor, unites with the su fur to roduce slag which rises to the to of the lat e or reservoir where it may be stinnned off, thus reducing the amount of sulfur in the molten metal. During this o aeration it appears that a small uuntity o the manganese unites chemicaily with the sulfur to form manganese sulfid which also rises to the top of the molten metal, after it is format, by the agitation produced by the oxidizing agent. So far as can be learned from a study of the process the above ap pears to be what actually takes place.

At the beginning of the process of removing sulfur from cast iron the temperature of the molten metal is substantially the same as the initial temperature of the metal in the Bessemer process. In the latter, however, the temperature increases great-l due to the oxidation of the carbon and t e silicon, by the air blast; while in the present process there is a gradual decrease in the temperature of the molten metal inasmuch as there is no oxidation of the carbon or silicon, or at any rate it is practically 12/52. This non-oxidation is in turn due-to the fact that only an amount of the oxidizing agent is introduced as will cause a slight boiling or ebullit ion of the molten metal, and I have found that this slight boiling of the metal sufliciently agi tates the metal not only to hasten the combination of manganese and manganese oxid with the sulfur but also hastens the separation of the manganese sulfid and the manganese oxid, thus formed, from the molten mass.

In irons low in manganese I put into the ladle ferro manganese to increase the man-. ganese so that there will be more of it to combine with the sulfur. I can also add ferro silicon, carbon or phosphorus by a chamber connected to the air pipe of the ladle to increase my carbon, phosphorus, silicon, or other elements through this chamber. As the air passes through the pipes into the ladle of iron provision is made whereby a siphon effect is created and draws into the molten metal the silicon, phosphorus, manganese, carbons .or other elements desired which are introduced to give to the metal the required amount. I also use carbon in different forms blown through this metal to give to the latter some extra heat. I use coke, coal, charcoal, phosphorus or other heat giving material to create and increase the temperature of the treated.

molten iron. It is not to be understood that this specific method of adding the elements having the heat giving properties is the only one, as I can introduce them into the bottom of the ladle before pouring the metal into the ladle and obtain substantially the same results. However, the method first described is preferable since it is more accurate- In addition I can also confine all of these elements in a cartridge or retainer and sink them to the bottom of the ladle ofmetal, the combination being such that it will melt at a lower temperature than the iron. When the elements confined in the cartridge are melted they are given up to the molten metal, part of the manganese being oxidized to form manganese oxid which unites with the sulfur of the molten metal to produce a slag, and the other elements, having heat giving properties, creating more heat for the metal.

My method is to be used in connection with blast furnace work, making pig iron then casting it into pigs. The method is capable'of use in all iron or steel foundries in which case the melted metal can flow from the cupola or furnace to this receiver and be treated by this method; or the ladle or receiver can be filled at the cupola and then be transported anywhere desired to be maining therein.

The process of melting iron chips and' casting them into pig iron has always been encountered with serious difliculty on account of the excessive amount of sulfur re- It is almost invariably found to contain .2 of sulfur which is very high. lVit-h this process I can reduce the a sulfur of'the molten metal made from chips down to .085, which apparently will open up a new field for iron melted. from chips and borings thereby enabling one to make pig iron out of this meltedchip metal that is so high in sulfur. By experiment it has also been found that 1000 lbs. of iron can be kept alive twenty-five minutes by'this' process, whereas it would otherwise have set in ten minutes. Iron was also taken containing sulfur .09 and after blowing it fifteen minutes the sulfur was reduced to .06. In another trial beginning with .05 of sulfur air was blown through it for two minutes and test showed it afterward to contain .035 of sulfur and .65 of manganese; after blowing the same batch three minutes longer the test showed sulfur .033 and manganese .52. The slag skimmed off the top of the metal showed sulfur .429 and manganese 2.16. In anothertest iron was taken containing .074 of sulfur, and after blowing'air through it for six minutes the sulfur was reduced to .0418. In all these tests just enough air was allowed to pass to keep the metal merely boiling.

Having described my process sufiiciently 5 100' to enable any one skilled in they art to operate the same, what I claim is:

1. The herein described method of removing sulfur. from cast iron containing manganese which consists in introducing the molten metal into a ladle or chamber, then oxidizing a part of the manganese and agitating the mass to hasten the combination.

of manganese and manganese oxid with the sulfur,

2. The herein described method of removing sulfur from cast iron which consists in introducing the molten metal into a ladle or chamber; adding a quantity of manganese; then introducing air to oxidize a part of the manganese and to agitate the mass to hasten the combination of manganese and manganese oxid withthe sulfur.

3. The herein described method of removing sulfur from cast iron which consists in introducing the molten metal into 3 a ladle or chamber; adding a quantity of manganese; then introducing an oxidizing dize a part of the manganese and to agitate ture in the presence of two subscribing Witthe massto hasten the combinatlon of mannesses. ganese and manganese o-Xld with the sulfur and also to hasten the separation of the WALTER PRINCE 5 manganese sulfid and the manganese oxid Witnesses:

thus formed from the mass. J. H. DORCH In testimony whereof I aflix my signa- I F. STACKHOUSE, Jr.