US2302615A - Briquette for the addition of molybdenum to ferrous alloys - Google Patents

Description

I UNITE!) me November 1 l 1942 we wee-T 0FFIQE 'BRIoU ET'rE'Fon THE annrrlou OF'MOLYBJ it DENUM-EOl EERROUS m x'molybuenum Compan N a corporation of pelaware I nanawmg. Application Api-iI-Z ,-.,Se1'-ia lNo. 339,751-

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The --pre's ent invention relates-to a novel ,and improved molybdenum: addition agent fora-the production of ferrous alloys:

Objects and advantages of: the invention will be set forth in-part hereinafter and in part will be obvious herefromf orvinay-be. learned by prac-i tice with the invention-the same being realized and attainedy-by: meansof the compositions, steps, processes and: instrumentalities :pointed out-tin the appended claims. 1 l

The invention con'si'stsinthe novel compositions;'; steps, processesp. combinations and line provements herein-shown and-described.

The present invention 'has for its object the provision of axn'ovel andaimproved. molybdenum containing alloying; agent which 1 is; of ,wide u efulness in "theiproiduction oi: molybdenum cons n ferrous alloys: Tnebinvention. further Heretofore molybdenum been added; liefer:

rous alloys,- byalarge'number of different-proc- 3:

esses involving "a wideyariety of diiferent addi: tion agents. Molybdenum sulfide or rr'1oly-b--. denite concentrates have been'proposed and used asan addition .agenirlzbnt have proved tobeef very: limited application 'due to the relatively large proportion of sulphur contained therein and introduced thereby into'the ferrous alloy. Molybdenum trioxide,- roasted .molybdenite and molybdenum dioxide, aIPOXidE? of molybdenum, have beenused asadditionagents; but their use has. almost invariably beenattended 'by exces sive loss of mo1ybdenum,- resulting. in auxincreased cost ofproducing thealloy, and furthe more their use has'been limited to the production of ferrousalloys-tocontain less than 1 per ofmolybdenum. Calcium molybdate; combine tions of lime with lower oxidesof molybdenum and mechanical mixtures of calcium oxide and molybdenum tri'oxide' have also been used as ad dition agents, but their use is limited to the pro duction of iron-molybdenum alloys containing:

.wvariousgvarieties vof ,Jfepro-molybdenum have also been-widelyused for the-productionofmolybdenum-bearing ferrous alloys, and while there is no practical limit to the. amount of molybdenumiwhichamay-be contained in the alloys produced-therewith, this type of addition agent-has necessarily increased the cost due to the extra operations required for the manufacture .of term-molybdenum. Ferro-molybdenum :has; the

added disadvantage that it sinks tothe bottom of the ladleand theresulting ferrous alloy is renfinolybdenum dared homogeneous only- .with dimculty, Briquettes of a molybdenum oxide with carbon have been widely usedandgwhile theyavoid manyof the disadvantages, of-the otheralloying agents; they produce-a boil, and when large'percentages oiggmolybdenumiareto beadded in this way; the

'gas;ievolution mayi-ibe -,-excessive, Molybdenum silleiduhas; also'beenzused as an addition agent where,sefairlyhighsilicon content in the resulta ingalloy ismnobiectionable;=- At other times, pure molybdenumpowder has'ibeen used as the: addition agent, but iaside ,fromthe relatively expen- 's iye, cost oi producing, molybdenum powder, the

absorption of. the molybdenum into the ferrous alloy is too slowlto ,be commercially desirable.

g lngeneral, the various ways in which molybdenum; has been'added to ferrousal-loy have been less effectivesubstitutes-for the universally useable'ferro-molybdenum, which has its relatively -high cost and-wits relativelyfhigh specific gravityas its primary commercial disadvantages. -In addition to the foregoing, there have been other minor ways propo ed for the addition of molybdenum to ferrous alloys, but these have not met with I any considerable commercial-use, and

among-them maybe mentioned the miXtures of molybdenum trioxides with silicon and/or ferrosil-icon. I

1 The present invention providesan economical molybdenum addition agent for ferrous alloys, which eliminates-the use of any'relatively expensive reducing agents, the availability of which less than 1 per cent of-inolybdenum, and have may berestricted, such as aluminium, silicon. magnesium and calcium, requires-a minimum of equipment for-its production,- eliminates, the objections which have existed with respect to all of the commercially-used addition agents set forth above, and does not result in the introducr tion into the molten ferrous metal of any foreign present invention provides a universally acceptaole molybdenum containing compound for theintr'oduction ofmolybdenuma into ferrous alloys at Root a're' a "crude. form of roasted molybdenite concentrates are partially rein duced to form crude molybdenum oxides or crude molybdenum metal powder containing isomeof, the molybdenum oxides as impurities; and this 1 reduced roasted concentrate is mixed intimately.

with relatively fine powerei'granular 'orflake like iron. The resultant intimate mechanical mixture of these substances is highly compressed to form briquettes which are preferably of uni};

form size. Due to the peculiar characteristics of the molybdenum compound and the iron par ticles, no foreign binder is needed for the coherence of this-mixture, and the briquettespreferably contain not more than a trace of carbon-or other impurities. 1 11 A 'It will be understood 'that'the foregoing gen eral description andthe'following"detailed del scrip'tion as well are exemplary and explanatory of the invention but are not restrictive thereof.

Referring now in detail to'the present preferred and ;illusti'ativeembodiments of the in vention, the novel and? improved molybdenum .containing' briquettes are"formed' from partially reduced roasted molybdnite concentrates .whioh molybdenum trioxide. "The roasted concentrates are""irediiced fywith'. car bonaceous inateri al-i'r'i'afbehivebt coke oven, and theredilction" is d cance ous: per cent molybdenumdioxide; from to 30 per cent of molybdenum oxidd lwhile the" remainder -ismetallic 1 molybdenum' and gangue; or,="-the r'duction may becarried on still further until-the molybdenum' 'ismresent as from 50-=to 60 'per cent metallic molybdenum, 20 to 30 per cent -molybdenum=oxide, -and=- the balance molybdenum dioxide and g'angue The reducing agent may-conveniently be carbon or some' other reducing agent -'s11ch as piwhwhich is substan tially entirely removed from the molybdenum compound by the end of "the reduction process. Preferably. not more than 0:25 carbonis con tained'in the briquettes as '-they are fii-ia lly made Thus? the reduced molybdenite'concentrates containfro'm approximately '7 .5%"to *l7f7' oxygen, while the crude metallic molybdenui'n or highly reduced molybdenum" oxides cdritaLin" from. about 7.5%" to as ccntr'aSted-WitH-the oxygen content 1 of rnolybdenu' m '-dic' 'xide' and the 33% oxygen content of 'molybdeniim-trioxide;'=

Y r The reduced roasted'concel itrates are generally e which 0 rough handling without excessive crumbling.

j In'use, the briquettes may be treated in prac- "ti'cally the same manner as is customary with its -r'chi-efzadirantages:

-W hat-.-I"c laim is:

per cent of the iron particles, although as little as 5 per cent oras much as 70 per cent of the iron particles may be added to the reduced molybdenum compound. This mixture is thoroughly mixed until the molybdenum containing particles and the iron particles are intimately mixed, and theresulting mixture is briquetted to form relatively large briquettes which may conveniently contain a predetermined weight of metallic molybdenum. During the briquetting operation, the

' intimately mixed particles of the reduced molyb- .-denum oxides-and the iron particles are subjected to. .-a relatively high pressure, and due to the dif ."ferent, nature of the materials, the mixture is .com'ressed into arelatively hard, coherent mass an be shipped and will stand considerable ferro-molybdenum. flfhey may be added to the steel -'furnace .or ladle, and the molybdenum is rapidly absorbed by the melting or molten steel. Similarly, they may be addedto the furnace or ladle during the manufacture. of molybdenum containing cast iron. The briquettes sink just below the-interface of the slag andmolten metal, the slag protecting the-metallic molybdenum from oxidation, -at the same-time that'it allows it to be rapidly dissolved in the molten iron or steel. Inasmuch as the briquettes do not sink to-the bot tomlof the ladle, the resulting alloy readily and quickly becomes homogeneous,v and no difficulty is experiencedthrough slowdispersion' ot the molybdenum throughout'theialloyz.

vJIhe briquettes containno foreign material, no added impiirities-"are introduced I into the"'alloy., and due to thefa'ct ,.that:-1. the molybdenumis present in the briquettes in partly. reduced form, the molybdenum ='is;put :into thesteel or iron withiialmostraniabsolute minimum of chemical reaction, onlyiferro-mo1ybdenum -having= less chemical reaction. 'Thus, the briquettes of the present invention can replace to advantage all of the .molybdenum addition =-agents which have heretoforel been used with theadded advantage that'theibriquettes of the present invention can be produced much more readily,.and with less expense than any of the other molybdenum addition: agents including. ferro -'molybdenum.

"Theinvention in its-broader aspects is not limited to the specific compositions processes and steps-described and departures may -be made therefrom within the scope; of 'the' accompanying -claims without departing from the principles amneinventionand' without-sacrificing =..=1 :"A':briqiiette for' the addition of molybdenum in the form of relatively small particles, the;iri

dividual particles or grains having a'ceriter which is largely molybdenum dioxide surroundedby "a considerable layer I which in turn'is coated with powiieredmetallic molybdenum.,' these successive -layers'= gradually merging into each otherand being formed as'the result of a' more intensive reducing action'on'the surface of the particlesu The iron to be'intimately-mixed withthe partially reduced molybdenum oxides may consist of powdered granular or'fiakelike ironcontaining the normal impurities, and even substantial amounts of iron oxide will not interfere with the results to be obtained.

Preferably the partially reduced roasted molybdenite concentrates are mixed with from 10 to 50 of olybdenum =1 monoxide;

to ferrous alloys consisting essentially of 'r'educed molybdenum trioxide containing from approximately "7.5% to 17% oxygen and ironparticles intimately mixed together. i

. 2.i.'A=' briquette for i the addition of' molybdenum to .ferrous; alloys consisting =-essentially1 of crude molybdenum powder containing from? approximately 7.5% to 11% oxygen'and iron particles intimately mixed together.

A briquette for-the addition of molybdenum to ferrous alloys consisting substantially entirely of .particles'of reduced molybdenum trioxide the outer portions, only'of which are completely reduced molybdenum trioxide and particles of iron intimately mixed together and highly compressed to form'a coherent mass.

4. A briquette for the addition of molybdenum ygttgg nismi tress Reierentt to ferrous alloys consisting substantially entirely of particles of highly reduced molybdenum trioxide containing less than 17% oxygen with the outer portions only substantially completely reduced to metallic molybdenum intimately mixed together and highly compressed to form a coherent mass.

5. A briquette for the addition of molybdenum to ferrous alloys consisting substantially entirely of particles of reduced molybdenum trioxide the outer portions only of which are completely reduced molybdenum trioxide and particles of iron intimately mixed together and highly compressed to form a coherent mass and containing less than 0.25% carbon.

6. A briquette for the addition of molybdenum to ferrous alloys consisting substantially of particles of reduced molybdenum trioxide the outer portions only of which are completely reduced molybdenum trioxide and from 5% to 7 0% particles of iron intimately mixed together and highly compressed to form a coherent mass.

'7. A briquette for the addition of molybdenum to ferrous alloys consisting substantially of particles of reduced molybdenum trioxide the outer portions only of which are completely reduced molybdenum trioxide and from 10% to 50% particles of iron intimately mixed together and highly compressed to -form a coherent mass.

ARTHUR LINZ.