US2134616A - Producing molybdenum alloys - Google Patents

Description

1 .poration of Delaware No Drawing t The present invention relates to new and usei ful improvements in alloying molybdenum with ferrous metals and moreparticularly' toja novel 'nd improved molybdenum addition agent i I Heretofore, molybdenum-bearing ferrous alloys havebeen, produced by the addition of molybdenum to the iron or steel either as calcium molybdate, some other molybdic acid salt, or as ferro molybdenunn However, each of these materials has its limitations and cannot beused universally "for onefreason or another. Calcium \molybdate and other equivalent molybdic acid salts are of satisfactory for the production of a .widerange of ferrous alloysin the blast furnace as well as in l5 theladle; but arenot satisfactoryfor the production of a11oys,- as in the electric furnace, where slag is objectionable. Ferromolybdenum is coniderably more costly than {calcium molybdate and its use is generally-restricted to those alloys for which calcium molybdate is] notsuited, al-

though,,except for the costof the material it is of quite general application. Calcium molybdate, however, requires the, production of the compound from roasted molybdenite, eitherby mixnga'nd heating to high temperatures, or by mixmg, wetting jandbriquetting. 1

Theprior patents and literature describe other processesiof producingmolybdenum alloys which have not come into commercial use, or are of very 30 limited commercialv application, and inseveral of them, themolybdenum is described as being I added to" the blast furnace, or to the molten ferrousmetal, in the form of roasted molybdenite or molybdic trioxide. These processes have 35 proved to be of. no commercial value, due to the g high loss of molybdenum through volatilization and entrainment, as molybdic trioxide is a very light powder and has a relatively low volatilizaq tion point. Consequently, these processes will Y, 40 produce a commercially satisfactory recovery of -molybdenum only where the molybdenum trioxide, or roastedmolybdenite, is buried in the charge. and will be trapped or absorbed. by the upper layers of the charge before it escapes from 45 the furnace. However, when the furnace is charged in thismanner, only one alloy can be produced from the charge and it is generally not desired to produce solarge an amount of any p particularmolybdenum alloy. Where the molyb-, 5 'denumtrioxide or roasted molybdenite is thrown in on top of "the slag, it is generally volatillzed before itmixes with the slag] and only a small portion is recovered in thealloy.

, Thepresent invention has for its object the 55 provision of a novel and improved composition of Application Jan 3 Claims. (01.15-3) o,

, matter for the "introduction of molybdenum into Arthur New York, n. 11., assignor to Climax Molybdenum Company,

New York, N. Y., a corferrous alloys, and also provides a novel andimproved form of molybdenum trioxide.

In accordance with the present invention, the,

' molybdenum is added tothefurnace or ladle in 5 the form of briquettes composed" of roasted molybdenite concentrates or molybdenum tri-' H oxide intimately mixed with a relatively small amount of still pitch; so as to forma hard, compact mass of relatively high specific gravity.

These briquettes are suitable for the production of ferrous molybdenum alloys either in the blast,

furnace, electric furnace, or by the addition of the briquettes to the molten metal in the ladle. By the use of these briquettes, molybdenum may be introduced into the ferrous alloy practically withoutlossup to 1% molybdenum in the final alloy, and with only relatively small losses of molybdenum even where the alloy contains as much as 15% molybdenum.

Specifically, the briquettes of the present inventionare preferably formed from roasted molybdeniteconcentrates, which are the technical grade of molybdenumtrloxide and contain from '19gto 90% ofmolybdenum trioxide. This roasted molybdenite is' mixed with ,a-quantity of still- 7 pitch whichserves as a binder for the roasted molybdenitafand the proportions are such that the briquettes contain-from 88 to 90% roasted molybdenite and from 10% to 12% ofstill-pitch. 3o 9 These briquettes are preferably cylindrical and may conveniently contain a predetermined'and uniform amount of molybdenum. In practice, it is convenient for them to have a molybdenum content of 2.50 pounds, as this size makes for easy handling, and these briquettes are of, sufficient size andweight to sink readily through the slag or into the molten ferrous metal. The uniform molybdenum content of these briquettes expedites the addition of the correct amount of molyb- 40 denum. 1 1 Q v The use of pitch as a binder for the roasted molybdenite is particularly desirable as itgenerally contains more than 90% carbon, and the quantity specified not only serves to bind the roasted concentrate firmly together into a hard compact mass, but also approximately provides the correct stoichiometrical quantity of carbon to combine with the oxygen in the roasted concentrate; thereby preventing a change inthe carbcn content of the final ferrous alloy. H The briquettes of the present invention are ex tremely economical due to the low cost and small of. the added material and also to the amount fact that they can be manufactured simply and pitch.

1. An alloying briquette comprising a solid mass of about 90% roasted molybdenite concentrates and about 10% pitch binder.

2. An alloying briquette comprising a solid mass of roasted molybdenite concentrates and a relatively small amount of pitch intimately mixed therewith and serving as a binder.

3. A composition of matter for use in producing ferrous-molybdenum alloys consisting of an intimate mechanical mixture of roasted molybdenite concentrates and a relative small amount of ARTHUR LINZ.