US943280A - Bessemerizing of copper matte. - Google Patents

Description

PATENT @FlilQE mrrn snares amass. c. smite, or BALTIMORE, MARYLAND.

N Drawing.

certain new and iiset'ul linpriivcm'ents in v such as. will enable others skilled in the art to which it appertains to make and use the same. H V v v ,In anapphcation for Letters Patent of the United. b tatesifiled by William H: Peirce 1 and myself jointly, under date of June 13th, 15 1908, Serial, Number 438,286, we have described at. length certain new tllld useful'improvements 1n-,the bessemerialn'g of copper matte m,a converter haymg'a non-ccrrodi- 'ble lining, which improi ementsinvolve the:

maintenance of the desiredi'eactions in the converter and the preservation intact of the converter lining as itexpands and contracts under the chang ng. heat conditioris to which 1t 1s-s'u,b ected, by conducting the air blast required for the blow through the 11011-001' the body of; the lining,

rodible lining and delivering it into the charge, while at the same time guarding it, during, transit, through the lining, against diminution of itsy'olume and leakage into In carrying out, ona commercial scale, the bessemerizing, of copper matte in a. con-- ,1 vcrter having a ;non-co,rrodible lining, and ,.witl1=tl1e employment of an acid flux, I have ascertained thatithe integrity of the lining is further endangered by the action of the slag produced luring tllbpElfitlDn, unless the process is conducted under such conditions, here naftei specified, as will nsure 40 against theattack f-the slag upon thelining.

These conditions may be briefly summarized asconsistii g in so proportioning'the amount v; and chara erof; tliesilicious flux added to H ,the bath molten matteto bebessemerizcd tutheyolume of the air blast admitted during ithe smelting blow that the siliclious flux willnot only, h lly-subserve its function of flux-' ing the iron and of adding it's/own content of matte-forming material to the 'bath, but

,will 'lorm a thin andfiu'ent slag capable of .t @tially attack: the non-corrodible linin 1 being readily pouredfotf and producible at such a temperati re that it will not substan- Specification of Letters Patent.

! BEEiSEIl/IERiZlING or oorrne MATTE.

Patented K D-ecu M 1969.

Application filed'Octobei 1, 1909. Serial No. 520,565.

In the practice of the invention, in order to obtain the maximum output, to the best advantage, from the converter, 1 llllblfllly molten matte of such large Volume as Will maintain fluidity during the blow. This bath at least, the diminution in volume due to the elimination of the iron from the charge as it is being converted by the smelting blow into whitc n'ietal. The matte-making constituents thus supplied, I further supple- "ment by adding additional molten inatte to the charge, from time to time as re i "The temperature or" the molten matte an tions is usually somewhat lower than that the matte in the bath at the termination the preceding blow, but, oi -course, it contains fuel in the shape of iron and sulfur, whose subsequent combustion in the next succeeding blow adds heat to the charge thereby counteracting the chillingcfi'ect of the-additions of silicious flux. in realizing I this-practice, I prefer to employ as the silicious flux a silicious copper ore, containing other metals, such as gold and silver, which, added to the matte increase its value and which are thus recovered incidentally without the necessity of a separate smelting opiron eliminated and shall have proc uced a thin fluent slag, and so that, atthe same time, Whatever matte-forming constituents 1t charge, or otherwise form therein a body of of molten matte of large volume, is main-.

forming constituents which supply, in part.

eration. in order to matte use of these sili-;.

exercised the desired Faxing effect u on the ore brick, or the like.

'erator, the molten slag will, when at a su table temperature, pr sent a yellowish ap the charge of matte 1n the converter.

The temperature of the matte, which had been lowered by the admission of the charge of silicious flux, is raised by the chemical reactions due to the blowing in of the air and the fiuxing of the fractional portion of iron eliminated; so that, upon pouring ofi the slag, the temperature of the charge is sufiiciently high to permit the addition of a further amount of silicious flux for} the fiuxing of the iron in the next succeeding fractional blow. A suflicient quantity of molten matte is likewise charged into the converter from time to time (usually after each fractional blow) until the final blow to White metal, so as to assist in the maintenance of the proper heat conditions and to maintain a'practically constant volume of matte within the converter. Toward the end of the smeltin conversion, the amount of silicious flux ad ed is somewhat diminished, in my usual practice, as will hereinafter more fully appear. Finally, immediately before the blowing of the white metal to blister copper, and after the slag from the last charge of silicious flux has been oured oif, I take precaution to leave in t e matte a sufiic ent uantity of iron to more than compensate for the silica present in those portions which have escaped the pouring off operation. This precaution is for the purpose of preventin foaming in the converter, which I fin will occur, if, after the final pouring ofi op eration, there is left a quantltiy of silica 1n excess of the iron still remaining in the white metal. In fact, as indicated, the amount of iron remaining in the matte, should be, in practice, somewhat in excess of what is necessary to satisfy the silica of the residual slag. It will appear in the slag in the form of thick pasty lumps or balls consisting principally of magnetic oxid of iron.

Referring generally to the operation as hereinbefore outlined, it is characteristic of' my discovery and invention that the process should be so conducted that the temperature of the thin andfluent slag produced at-the termination of the several fractional blows during the smelting conversion shall remain insufiicient to permit the slag to substantially attack the non-corrodible lining, which latter I prefer to make of magnetite brick, chrome To the eye of the oppearance. At higher emperatures, the slag will assume a cream whitetinge, from which it will, at still higher temperatures, attain a white color. These cream white and white colors indicate that the temperature is too high, inasmuch as under such conditions the slag will seriouslvattaek the lining, finally breaking it down and decreasing its life to a degree incompatible with fair commercial results. 7

Referring now, more particularly, to the specific details for the preferred practice of my invention, I will assume the employment of a con verter having a non-corrodible lining and twyers, such asillustrated in application Ser. N 0. 38,286 hereinbefore referred to, and that the lining is in a highly heated inches below the level of the twyers, when the furnace is in-its normal position. The.

matte thus charged (say forty (40) per-cent. copper matte) may conveniently be obtained from any of the usual matte-producing fur:

na'ces' .Its temperature may vary from say.

1900 to 2300 degrees Fahrenheit. .The skilled furnace man is able to judge from its appearance, with substantial accuracy, as;

. to its temperature and as to the quantity'of silicious fiuxto be supplied as the first, addition. l

As soon as the converter has received its initial charge of matte, the silicious flux is added, in quantity appropriate to the temperature of the matte, the amount of the rst addition being usually smaller than the subsequent additions, (because of the lesser temperature of the: initial body of matte,) until near the termination of the entire fluxing operation. The silicious flux may co'nsistsay of an ore containing 60% of silica, 10 per cent. of copper and 8 per cent. of iron, or, say, of an ore containing 40% of silica, 20 per cent. of copper, or of somewhat other like ores, preferably containing metal values which will enter the matte, as, for instance, copper, as just noted, or higher metal values such as silveror gold, either with or without copper. The amount of silicious flux thus added for the first fractional blow will usually be about six thousand (6000) pounds, more or less, according to the temmatte. Blowing is then proceeded-with for a period ofv about forty-five (45) minutes, a

yo'lume n in admitted-impel to about eaaa six thousand 6006} to seven thousand (70th); cubic i'tcet per minute, The furnace I .3911 is able to determine the timetfor inter I rupting. the blow by'observing the condition l of the slag, which should be thinly fluid and I of a yellowish color (comparable to the color of melted butter). To observe the color of a the slag, it is necessary for the furnace man to rotate the furnace in such manner 'as-to i raise the twyers above the level of the charge and shut oi'fthe air supply, whereupon the charge will subside, and the slag which has been in agitation will come to rest on the surface of the matte. If it has attainedthe desired'color and is correspondingly thinly fluid it is in condition to pour but if-it has not reached that stage, the furnace man again turns'on the air supply and by rotating the furnace back to its original position resumesthe blowing operation.

The normal temperature of; the converter and the temperature of the slag at the time when it should be poured variesv from-say 2100 degrees to 2400 degrees Fahrenheit. Should the blowing be continued after the slag has attained these temperatures, its temperature would rise'rapidly andits-color would change from, ayellowish tint to a cream white and finally to a dazzling white. At these higher temperatures the slag, still thin and fluid would begin to attack .the magnesite brick lining, and would: rapidly wear it down along the surfaces of contact principally along the zone of the twyers. A continuation of the blow beyond the point where the thin and fluent slag of yellowish tint is obtained would ultimately result in encumbering it with additional masses ;of pasty and lumpy slag consisting principally of magnetic oxid or iron. y

At the termination of the first fractional blow, the percentage of iron inthe matte has been reduced from say 30% to about 22% and the iron thus oxidized has, as -bove, 45 indicated, united with the silica. present. The interruption of the blow at thisstage, is necessary for the reason that if continued further the passage of an additional quantity of iron into the slag would make it still more fusible and the oxidation of the additional quantity of iron would raise the temperature of the slag within the furnace to such a degree that it would attack the magnesite lining along the twyers as described' In addition to judging by the color of the slag as to the time at which to terminate 'the first fractional blow, the furnace man can further confirm (though with less certainty) from the color of the products of combustion issuing from the converter the time time. the products of combustion have a bluish cast and exhibit incandescent pan ticlcs of fused slag in very small qua'ntity.

A still further guide to the furnace man as to the proper time at which to interrupt the blow is afforded by the expedient of inserting at a time approaching the expected end of its duration, an open-ended iron pipe, of say an inch bore, into the coni 'er'ter, from above, through the opening for the pouring ofl of the slag. This opening, after the charge has been admitted, is filled with clay and the pipe referred to is inserted through a small aperture made in this clay filling. The pipe may conveniently be, bent atits outer or handle end, so as to be readily manipulated by the furnace man, and, by lowering its free or testing end into contact with the slag, the furnace man can determine by the resistance offered to its downward movement whether the slag is in condition to be pouret. If it' has not reached the thin and fluent stage, the pipe will not readily penetrate it, but as soon as that stage has been attained, the fact is made manifest, by the practical absence of resistance to the downward movement of the pipe, incident to the circumstance that the slag has attained the requisite thi i'nessand fluidity. Furthermore, the ascertainment of the proper period for terminating any oneof the fractional blows, gives to the furnace man a fairly accurate intimation as to the ,desired time for terminating the HQXtSHC- ceeding fractional blow, inasmuch as it instructs him as to the general behavior'of the particular charge of matte and flux treated, under the other: furnace conditions prevailing.

At the" termination thin and fluent slag is oured from the top of the matte in any suitable manner. The

slag th'us' poured will usually be found to contain in the'neighborhood of 47% or 48 of iron and 27% of silica.

wever, upon the, composition of flux, and

,will be proportionally less if the flux containsjalumina. I It is 'desirable to obtain like sla'gsthroughout the entire smelting conver- "sion; therefore, the amount offlux added and the lengthof each bl'ast period are so related that this normal slag shall alwav produced at theiend each fractional blow duringthe s eltin'g"eon version, within say a few per cent. the way ortlie" other.

I Afterpoiiring off theslag at'the termination of the first fractional 'blowfa further addition f molten'matte, together'with siliti e re is made, in order to reestablish the yell; sirable ',cons t'ant fvolume in theconverter up to the when the blow should terminate. At that i final blow from white metal 't'o'blister'coppen, 'I. e amount of the'addit'ional'matte added will vary according to'the grade of employed, but, in theiristancesupof the'first blow, the

\ The amount ot' silica present in the slag will be dependent.

which has served rich ed by the charging or posed will consist of about. eight (8) tons after each fractional blow; so that, including the initial bath of forty (40) tons, the converter, at the beginning of the last blow from white metal to blister copper, will have received a total charge of about 100 to 110 tons of matte of say 40%. copper. If the matte is of higher grade, a proportionally smaller amount of matte will be required to produce thesame. volume of white metal. The specific gravity of the matte, of course, increases as the bath becomes enthe elimination of the iron and additional matte into the converter, the white metal finally obtained containing about 78 to S0 per cent. of copper.

In taking oi? the last slag, prior to the so-callcd simple conversion or blowing to blister copper, it is impracticable to remove the converter.

all of the slag. Consequently, if an excess of silicious flux has been added before finishing the last fractional blow of the smelting conversion, there will be left floating on the white metal an amount of sla ing quantity containing unsatis ied silica. In order that this unsatisfied silica shall not become a source of future trouble, the last fractional blow of the smelting conversion is so conducted that there is left in the white metal a suflicient amount of iron to satisfy the silica of the residual slag referred to. In fact, in order to insure the full satisfaction of the silica in the residual slag, the amount of iron left in the white metal is in excess of that theoretically required; Consequently, during the blow to blister copper the silica of the residual slag will be more than compensated by the iron, and the ex-' cess of iron will pass into the slag principally as magnetic iron oxid, forming therein what is known as f ball sla-g. The presence of this ball slag, indicative of the full satisfaction ofthe silica, is a complete assurance against foaming in the converter during the blow to blister copper.

The slag present in'the converter at the termination of the blow to blister copper is very rich that considerable time would be required and ditti'culty experienced in removing.it. It is, therefore, left in the converter, aiidthe blister copper is tapped from underneath it. It is, therefore, essential tointroduce the next initial bath of matte into the, con- -verter quickly in order to prevent-this rich copper slag from sticking to the bottom of Moreover, by leaving this rich copper slag in the converter, its copper is recovered during the next succeeding smelting conversion. It will be understood that by the expression non-corrodible lining as employed the specification and claims, I mean a linmg of a non-acid character. such, for inof varyin copper and of such a. nature stance, as the magnesite brick or chrome brick lining, or the like, hercinbefore referred to. I

Having thus described my invention, what I claim is:

1. The method of bessemerizing copper matte in a converter having a non-eorrodi ble lining with the employment of an acid flux, which consists in forming a molten bath of matte in the converter of such volume as to retain its fluidity as against losses by radiation during the blow, and so proportioning the amount and composition of the flux to the volume of air blast admitted that at the termination of the blow there will result a thin and fluent slag at a toniperature insufiicient to substantially attack the lining; substantially as described.

2. The method of bessemerizing copper matte in a converter having a non-corrodible lining, with the employment of an acid flux, which consists informing in the converter an initial bath of molten matte, adding thereto a charge of acid flux containing 'fiiatte-forming constituents, blowing the matte until a portion of the iron therein contained is fluxcd' and the matte-forming material from the acid flux has become incorporated with'the initial body of molten matte and a thin and fluent slag has been formed at a temperature insufiicient to substantially attack the lining; substantially as described.

3. The method of bessemerizing'copper matte in a converter having a non-corrodipile lining, with the employment of an acid ux, verter an initial bath of molten matte, adding thereto a charge of acid flux containing matte-forming constituents, blowing the matte until a portion of the iron therein contained is fluxed and the matte-forming material fromthe acid flux has become inwhich consists in forming in the con corporated with the initial body of molten matte and a thin and fluent slag has been formed at a temperature insufiicient to substantially attack the lining, ouring off the said thin and fluent slag, a ding an additionalbharge of molten matte and of acid flux containing matte-formin materials, blowing the matte until a furt er quantity of iron is fiuxed and the matte-forming material of the additional char e has been in-.

corporated with the body 0 molten matte and a thin and'flucnt slag has been formed, as before, and repeating these operations successively, thus fractionally fluxing the iron and maintaining a substantially con stant volume of matte in the converter, until .thejmatte' is in condition to be blown to blister copper; substantially as described.

4 The method .of bessemerizing copper matte in a converter having a non-corrodible lining and with the employment of an 112;; which consists in preventing foam:

peuring of? operation; substanblow to- .ELIAS A. 0. SM??? Witnesses: v

' JQHN C. Pnmrm,

LAURA the converter by leavm in the mdken tially described. 1c th termma'tmzl 01 191? p testnnony-wnereof E n slgnatura, r L the mm 11' Oil 5 3110? of two wltnesses.