US3865573A - Molybdenum and ferromolybdenum production - Google Patents

Abstract

Novel molybdenum metal products may be obtained from higher molybdenum oxides by means of gaseous reduction in a twotemperature staged process utilizing a reductant recycling system. The process is amendable to provide a ferromolybdenum product in briquette form by co-reduction of iron and molybdenum oxides and results in an economical, low oxygen content mixture of particulate metallic molybdenum and iron.

Description

imite i States mm 1 Neumann et al.

1451 Feb. 11, 1975 1 1 MOLYBDENUM AND FERROMOLYBDENUM PRODUCTION [73] Assignee: Kennecott Copper Corporation,

New York, NY.

[22] Filed: May 23, 1973 [21] Appl. No.: 363,284

[52] U.S. C1. 75/3, 75/84 [51] Int. Cl. C22b l/l4, C22b 49/00 [58] Field of Search ..75/84, 3; 29/192 R [56] References Cited UNITED STATES PATENTS 1,315,859 9/1919 Pfanstiehl 29/192 R 1,401,924 12/1921 Sargent et al.. 75/84 1,659,205 2/1928 Lederer 75/84 X 2,107,279 2/1938 Balke et a1 75/84 2,398,114 4/1946 Rennie 1 75/84 2,763,918 9/1956 Megill 1 75/84 X 2,776,887 1/1957 Kelly, Jr. et a1. 75/84 X 3,053,614 9/1962 Foos et al. 75/84 X 3,264,098 8/1966 Heytmeijer... 75/84 3,407,057 10/1968 Timmons 29/192 R X 3,622,301 11/1971 Mehl et a1 75/84 X FOREIGN PATENTS OR APPLICATIONS 303,359 6/1971 U.S.S.R 75/84 Primary ExaminerA1len B. Curtis Attorney, Agent, or Firm-John L. Sniado; Lowell H. McCarter [57] ABSTRACT Novel molybdenum metal products may be obtained from higher molybdenum oxides by means of gaseous reduction in a two-temperature staged process utilizing a reductant recycling system. The process is amendable to provide a ferromolybdenum product in briquette form by co-reduction of iron and molybdenum oxides and results in an economical, low oxygen content mixture of particulate metallic molybdenum and iron.

12 Claims, 2 Drawing Figures MOLYBDENUM AND FERROMOLYBDENUM PRODUCTION BACKGROUND OF INVENTION Molybdenum has long been used as an alloying additive in the production of stainless and alloy steels. The general practice for all grades of alloy steels is to charge the required quantity of molybdenum or molybdenum trioxide along with the scrap before melt down.

In the process of melting down, if the oxide is exposed to the atmosphere at high temperature, there will be some losses due to vaporization of the molybdenum oxide. After melt down the final adjustments to the molybdenum level in the alloy steel are made using ferromolybdenum. This is because ferromolybdenum has no detrimental effect on either the bath oxygen or carbon level as would occur if molybdenum oxide along were used. In addition, the use of ferromolybdenum increases the rate of dissolution and bath homogenization and minimizes loss by volatilization.

It would be desirable to use a ferromolybdenum product for all alloying purposes in steel for the above reasons, but the high cost of ferromolybdenum produced by the thermite process has prevented its general use. If a more economical method of production could be found, the above mentioned advantages could be utilized for all stages of the steelmaking process.

SUMMARY The term molybdenum oxide or molybdenum oxides as used hereinafter is defined as technical grade molybdenum trioxide (M containing inconsequential trace impurities and minor amounts of molybdenum sesquioxide (M0 0 and molybdenum dioxide (M00 It is to be understood, however, that molybdenum trioxide of any purity may be used in the process to make the novel product.

The novel molybdenum product, for use in the alloying of steel, is made by a novel process in which molybdenum oxide is stepwise reduced to molybdenum dioxide and then to molybdenum metal by hydrogen, reformed gas, or cracked NH reduction. The first temperature stage is carried out at about 500-600 C to reduce the molybdenum oxide to molybdenum dioxide. The final reduction of the molybdenum dioxide to molybdenum metal takes place in the second temperature zone at about 800 900 C.

In another and more preferred embodiment, a novel ferromolybdenum product is made by the process of this invention by premixing molybdenum oxide and iron oxide. The mixture is then stepwise reduced such that in the first step essentially all of the molybdenum trioxide is reduced to molybdenum dioxide and little if any iron oxide is reduced. In the second step, at temperatures between about 800900 C, reduction of the molybdenum dioxide is completed to essentially all metallic molybdenum and essentially all of the iron oxide is reduced to metallic iron.

In yet another embodiment molybdenum oxide and iron particles are mixed. The mixture may then be stepwise reduced such that in the first step the molybdenum trioxide is reduced at temperatures of about 500600C to molybdenum dioxide. In the second step the molybdenum dioxide is reduced to metallic molybdenum at temperatures of between about 800-900C.

Since the iron is already in the metallic state no reduction thereof is required.

The molybdenum oxide, premixed molybdenum oxide/iron oxide, or premixed molybdenum oxide/iron charge is preferably in briquette form to facilitate handling and complete gaseous reduction. The gaseous reducing agent, preferably a hydrogen containing gas, is supplied to the two temperature zone furnace in a countercurrent fashion and at least a portion of the gaseous reducing agent is recycled for nearly complete utilization of reductant. It should be particularly pointed out that at no time during the processing do the molybdenum or iron melt. As a result the product contains discrete or individually distinct particles of metal. The briquetting provides only surface bonding for ease of handling the product.

The metallized product may be crushed and briquetted to provide a surface bonded briquette having a specific gravity of between 4.5-7, which is sufficiently dense to enable penetration of steel making slags when making steel alloying additions.

The novel product of the instant invention may be in one or more forms. In one form the product consists essentially of a briquette of discrete or individually distinct particles of molybdenum metal. In another form the product consists essentially of a briquette of mixed discrete or individually distinct particles of molybdenum and iron. The iron may be from about 5 to about or more weight percent of the briquette. The final product contains less than about 7 percent by weight oxygen and is essentially carbon free.

Specifically, the present invention enables the economical production of a metallized ferromolybdenum product which displays excellent properties for purposes of making steel alloying additions. The reduction of oxides takes place in the process without carbon and other harmful contaminants entering the product, and ultimately ending up in the alloy steel. Further, the oxygen content, which can change the carbon level in molten steel by reacting to form carbon monoxide, is diminished to below 7 percent in the reduction. Finally, the process takes place at moderately low temperatures and hence does not involve high temperature, high cost melting and alloying of molybdenum and iron.

The principal object of the present invention is to provide a method whereby molybdenum in its higher oxidation states may be economically reduced to a metallic product without contamination by carbonaceous materials.

A secondary object of the invention is to provide a metallized ferromolybdenum product of individually distinct particles loosely bonded that is suitable for use as an alloying additive in steel.

A further object of the invention is to provide a carbon free metalized molybdenum product, containing less than 7 percent 0 and sufficiently dense to penetrate steel making slags when making molybdenum alloying additions to steel.

DETAILED DESCRIPTION OF INVENTION FIG. I is a diagrammatic view showing steps of the method;

FIG. 2 is a graph showing the rate of reduction of molybdenum oxide and mixtures of molybdenum oxide and iron oxide.

Referring to FIG. 1, the raw materials, molybdenum oxide and iron oxide, are blended together with water and briquetted prior to introduction to kiln. Zone I is operated at about 600 C, which is sufficient to cause the reduction of the molybdenum trioxide to molybdenum dioxide, in the presence of a reducing gas such as hydrogen or carbon monoxide. The solids 11, an intermediate product consisting essentially of molybdenum dioxide (and unreduced iron oxides), move from Zone I into Zone II of the kiln where the temperature is maintained between about 800-900 C. In Zone [I both molybdenum dioxide and the iron oxides in the intermediate product are reduced to provide a metallized product 13 containing a minimum amount of oxygen and is essentially carbon free. The metallized product 13 exits from the kiln and may subsequently be mechanically crushed and briquetted to form the final product, which is a surface bonded briquette of particulate metallic molybdenum with up to about 30 weight percent or more metallic iron particles, having a specific gravity of 4.57, essentially carbon free, and containing less than 7 percent oxygen.

The preferred reductant is hydrogen, which can be introduced as dissociated ammonia. The fresh dissociated ammonia, or make-up reductant 3, is combined with a stream of recycled gas reductant and the two streams together enter the kiln as the reduction gas feed stream 9. The fresh dissociated ammonia is, of course, a constant percent by volume nitrogen, and 75 percent by volume hydrogen, so that the total feed stream 9 content is dependent on the composition of recycled gaseous reductant 5 and the volume ratio of recycle gas to make-up gas. These reductant volume considerations are critical in the present invention for purposes of effecting essentially complete utilization of available reductant for each specific molybdenum oxide/iron oxide charge composition.

The feed gas reductant 9 enters downstream to the solids flow 13 and makes its way countercurrently through Zone II. A portion 15 of the gas leaving Zone II is recycled around Zone ll after condensing out the water. The remaining portion 17 of the reducing gas from Zone II continues into Zone I to reduce the molybdenum oxide to molybdenum dioxide. The overall reaction in Zone I is exothermic and is completed very quickly. As a result, the reductant in this zone does not necessarily need to be passed countercurrently to the solids flow. In the present process, however, it is convenient to pass the gas countercurrent in Zone I as it exits from Zone II. The Zone ll endothermic reduction of molybdenum dioxide to its metallic state is much more difficult than the trioxide reduction of Zone I, and hence the countercurrent reductant flow is desirable to effect maximum driving force for completion of the reaction.

Referring to FIG. 2 there is shown a plot of time versus the percent weight loss at two reduction temperatures and two compositions. The horizontal broken lines A, B and C represent theoretical weight loss for: A Pure molybdenum trioxide, B technical grade molybdenum trioxide, and C technical grade molybdenum trioxide containing sufficient iron oxide to result in a product containing weight percent iron.

Materials The starting materials may be less than 100 percent pure metal oxides. The process is particularly attractive for the use of technical grade molybdenum oxide. Any impurities, including unreduced oxides, merely pass through the process without significant effect on efficiencies or final product. This is largely true because of the relatively low temperatures used in the process. At higher temperatures sintering would have the ill effect of hindering complete reduction by blocking the path of gaseous reductant to the inner regions of the briquette. The low temperatures employed in the process do not present this problem. The impurity limits tolerable in the raw materials, therefore, would be dictated only by the end product requirements.

The process is useful in the reduction of molybdenum oxides alone or in the reduction of molybdenum oxides mixed with iron oxides. The presence of the latter is desirable if the end product is to be used as an alloying addition in steels. Among other things the process is unique in providing for co-reduction of iron oxide rather than mere blending of metallic iron with a reduced molybdenum product (See U.S. Pat. No. 2,302,615). In the present invention, the process is adaptable to meet the presence of iron oxides in terms ofthermodynamic considerations and volume of reductant supplied. The basic parameters, which may be adjusted to provide for a change in the composition of the oxide charge, are the temperature of the kiln zones and the volume ratio (at steady state) of the recycled gas reductant to make-up gas.

In order to prevent the reoxidation of a pure metallized molybdenum briquette once a steel alloying addition is made, it is desirable that the molybdenum be dissolved as quickly as possible in the steel melt. To accomplish this quick dissolution, a quantity of iron is introduced with the molybdenum into the steel melt. Dissolution in the steel melt is relatively rapid since the novel product of this invention is a loosely surface bonded briquette of discrete particles of metallic molybdenum and iron.

In the final metallized ferromolybdenum alloying agent, a quantity of iron in excess of 15 percent has been found to be beneficial. Specifically, an iron con centration in excess of 15 percent in the briquette product has the effect of promoting rapid dissolution of molybdenum in the steel melt and contributing to a very high recovery of molybdenum in the cast alloy steel. The iron so provided is sufficient to ensure that all the molybdenum present will dissolve at steel making temperatures without the formation of high melting point phases as the briquette disintegrates in the melt. The advantage of supplying sufficient iron in the briquette for complete, rapid dissolution of the molybdenum is the avoidance of both reoxidation and loss of molybdenum in the slag, and the settling out of heavy refractory molybdenum bearing compounds at the bottom of the vessel which might cause problems with subsequent heats.

PROCESS CONDITIONS In using the process of the present invention, the Applicants have found that several novel products may be produced which are particularly useful as alloying additions in the preparation of alloy steels. The present process is adaptable to provide for production of these various products. For example, the temperature and gas reductant levels may be altered to provide for the reduction of 100 percent molybdenum oxide starting material or molybdenum oxide and iron or iron oxides in any desired proportions. A practical limit is up to percent iron oxide in the starting material. The reduction may also be carried out in rotary kilns, belt furnaces, or fluidized beds, as long as the temperature stages and gas recycling are maintained. The Applicants have found that the presence of a 30 weight percent iron addition decreases the reduction time relative to molybdenum oxide alone by 40 percent with consequent advantages in reducing the size of the equipment.

In Zone I the molybdenum oxide is reduced to molybdenum dioxide between about 550650 C. At temperatures in excess of 650 C molybdenum trioxide is known to volatize. For this reason the first stage of the process is carried out below 650 C. At this temperature the iron oxides are not appreciably reduced to lower oxides or iron metal.

If acceptable utilizations of the hydrogen gas are to be realized, thermodynamic considerations in the reduction of molybdenum dioxide in the second stage requires that the reaction be carried out at higher temperatures than in the first stage. The greatest improvement occurs when the temperature is raised to at least 800 C with less significant benefit occurring above 900 C. In addition, increasing the temperature has a marked effect on the rate of reduction, the time required being reduced by a factor of 3 when the temperature is raised from 800 to 900 C. FIG. 2 illustrates this. Equipment design considerations and energy requirements preclude using much higher temperatures, so that 800900 C is considered an optimum compromise, though lower or higher temperatures could still be used to achieve the same results in terms of the products produced. The relatively low temperature processing in the present invention is an essential feature of Applicants process. Applicants have found that they are able to produce a ferromolybdenum product from iron and molybdenum oxides without fusing at the high temperatures used in conventional ferromolybdenum production. Instead, the Applicants are able to co-reduce the oxides at temperatures not in excess of 900 C.

Reductant In practicing the present process, hydrogen gas has been found to be the most suitable reductant, although other gaseous reductants such as carbon monoxide or reformed hydrocarbons may be used. The Applicants prefer that the hydrogen source be cracked ammonia because of its low cost. The feed gas 9, (recycled plus make-up), will be about 50% H2/50% N depending on the proportion of iron oxide in the starting material. Overall, the feed requirements are calculated on a stoichiometric basis for the completion of the reduction reactions, and sufficient make-up gas is supplied to the recycle stream to meet the stoichiometric requirements and the furnace losses.

The reductant gas feed 9 to Zone ll must be such that the ratio of hydrogen to water vapor required from thermodynamic considerations for completion of the reduction is maintained, in addition to providing sufficient hydrogen as required by the reaction stoichiomet- The Zone I reaction is not appreciably altered by the partial pressure of hydrogen to partial pressure of water vapor ratio, and no adjustment in the stoichiometric calculations need be made with respect to the reductant requirements for Zone I. Therefore, for maximum utilization of reductant, only enough reductant to complete the molybdenum trioxide reduction to molybde num dioxide is allowed to continue countercurrent into Zone I. The remaining gas 15 from Zone II is recycled through a condenser to remove the water therefrom and fed back 5 to the feed stream 9 for Zone II. It is necessary to condense and remove water from the recycle gas since the effect of the water vapor pressure on the reduction rate is negative in Zone II.

The Novel Metallized Products The preferred product for alloying of ferrous metals is produced in the novel process from technical grade molybdenum trioxide and a mixture of iron oxides such that the iron content of the product is between 030 weight percent. The molybdenum oxide and iron oxide are co-reduced to produce the desired metallized product. While 30 weight percent is the preferred limit on iron oxide in the batch charge, the amount of iron is not restricted to this by the process. The product is characterized by being a loosely bonded, preferably surface bonded only, briquette of discrete or individually distinct particles of reduced metal and will contain less than 7 percent by weight oxygen and be essentially carbon free.

The Applicants prefer that the product be a briquetted mixture of coreduced metallic particles of mo lybdenum and iron. The novel process, however, is entirely suitable for reduction of molybdenum trioxide alone, or molybdenum oxide mixed with iron, which can be later briquetted and used directly as an alloying agent.

Finally, the process is adaptable to be used in producing a metallized ferromolybdenum product from the mixed sulfides of molybdenum and iron. In a novel roasting step, the M05 and FeS (pyrite) may be coroasted to yield mixed oxides which are then briquetted and charged directly in Zone I of the furnace in the novel process. This additional step in the process is particularly attractive from an economic standpoint because the metal sulfides are generally the least expensive source of molybdenum and iron. The process produces a metallized ferromolybdenum product from these crude raw materials with essentially complete utilization of reductant.

Applicants have found in practicing their process that the physical form of oxide charge is important. Preferably the starting materials will be particulates in the size range from about minus 20 to about minus 325 mesh. Table II below presents a typical size distribution range for technical grade molybdenum trioxide. Iron oxide particles should be within same general size range. The reduction steps, for example, may be carried out in shallow beds of oxide powders but unreacted core and handling problems may decrease the gas utilization efficiency of the process. The Applicants, therefore, prefer that the molybdenum and iron oxides be blended with water and briquetted prior to reduction. Around 3 percent water has been found sufficient for making the green briquettes for feeding to Zone I reduction. This form allows the reducing gas to effectively reach the entire volume of material.

After reduction, the metallized product may be rather porous so that crushing and rebriquetting is necessary to densify the material for subsequent use. Molybdenum alloying additions to molten steels must sink through the steel slags which float on the surface of the molten metal. These slags have specific gravities in the range of 3-3.5 so that the metallized product must be compacted to a specific gravity in excess of 3.5 in order to penetrate the layer of slag. To accomplish this, the Applicants have found that the metallized ferromolybdenum product of the inventive process may be crushed and briquetted to a specific gravity of between about 4.5 and 7. A metallized ferromolybdenum briquette compacted to 4.5-7 specific gravity is entirely suitable for the alloying addition and results in high yields in the steel. The higher density of the briquette enables it to penetrate the steel slag and be delivered to the molten steel while the iron enables the molybdenum to dissolve easily in the molten metal. While it is apparent that higher density briquettes could be obtained it is preferable to not exceed a specific gravity of 7. With Applicants novel product 100 percent of the reduced molybdenum in the briquette is recovered in the steel rather than a significant proportion being lost in the slag.

The metallized ferromolybdenum product need not be 100 percent reduced for use in the steel alloying process. With almost 100 percent utilization of reducing gas, some oxygen may necessarily remain in the product. The quantity of oxygen associated with the molybdenum and iron in the product, however, will always be less than about 7 and preferably in the range of -2 percent by weight.

Without limiting the above described process, the following examples are illustrative of the features of the invention.

EXAMPLE 1 Reduction of Molybdenum Oxide to Metallized Product Molybdenum oxide (technical grade molybdenum trioxide) is briquetted and charged to the low temperature end of a moving grate kiln operated at distinct temperature zones of 600 C and 900 C. The assay and size distributions of the molybdenum oxide are shown in Tables I and ll. The speed of the moving grate kiln is set so that the briquettes will be totally reduced during the passage of the molybdenum oxide therethrough. This usually takes place when the oxide has been in the hot zones for 45 hours.

The reducing gas, dissociated ammonia, is passed countercurrent to the solids flow. The feed stream of dissociated ammonia enters at a rate of around 2 moles ammonia for each mole of molybdenum to be reduced. After the reductant passes through Zone ll at 900 C, a bleed stream removes all but 1 mole of hydrogen for each mole of molybdenum trioxide to be reduced according to the reaction MOO3+H2 MOO;Z+ (1) The remaining reductant from Zone ll is recycled through a condenser to remove the water and then back into the feed stream. The recycle portion brings the overall feed composition to H /50% N In the process approximately 10 moles H N are recycled when the reactions reaches steady state. This results in a hydrogen efficiency approaching 100 percent discounting leakage losses.

The molybdenum oxide is reduced completely in Zone I to molybdenum dioxide which is further reduced to molybdenum metal in Zone ll. Oxygen in the final product is no more than l2 percent as determined by the comparison of the actual weight loss with that calculated from the molybdenum content. It is calculated that no more than about 0.32 lb. of NH is used for every pound of molybdenum metal produced. This compares with 0.83 lb. NH /lb. molybdenum with no recycling of hydrogen. The rate of weight loss for Examples l and ll are shown in FIG. 2. For comparison, the rate of weight loss is shown for the same materials at 800 C. The expected weight loss is also shown (broken line A) based on an initial molybdenum content of 60 wt. percent, as analyzed for this particular batch of material, and assuming that the only oxygen present was as molybdenum trioxide. It can be seen that at 900 C the weight losses were slightly higher than calculated and may be attributed to the reduction of oxides of the other metals present as minor impurities.

EXAMPLE ll Co-Reduction of Iron Oxides and Molybdenum Oxide The process of Example I was followed but with millscale blended and briquetted with the molybdenum Table I Assay of Molybdenum Oxide Molybdenum Iron Copper Lcad Sulfur Oxygen 58-62 1 0.4-0.8 ems-0.030 0.04-0.34 29-31 T ble II oxide such that the product would contain 30 wt. percent iron after reduction. (Millscale FeO 60 wt. I Fe O 25-30 wt. Fe -,O 5-10 wt. by x-ray f of Molybdenum analysis overall composition FeO by hydrogen reduc- Scree Rammed tion) The briquettes measured about At inch in diame- 30 ter and V2 inch long and weighed about 5 grams each. :28 :28 {Q22 60 Furnace temperature in Zone I remained at 600 C but 22:30 the dissociated ammonia feed was increased to 2.6 l 1053 moles per mole molybdenum. Again 1 mole H per :lggl'gg 5:}; mole molybdenum was allowed to proceed from Zone 230+ 270 2.32 ll into Zone I and the remaining 9.8 moles N H (at 332 325 3:82 65 steady state) were recycled through the condenser and into the dissociated ammonia feed stream. Overall feed composition (recycle plus makeup) was 56.4%

N /43.6% H and 0.42 lb. of ammonia was used for every pound of molybdenum metal reduced. The densities of various process materials are shown in Table 111.

Table [11 Density of Process Materials Material Specific Gravity EXAMPLE Ill Effect of Recycle Ratio around Zone 11 on Hydrogen Efficiency Using the process of Example 11, again with the mill- EXAMPLE 1v Recovery of Ferromolybdenum Product in Steel The object of the ferromolybdenum product is to provide a low cost means of adding molybdenum to steel with high yields and with a minimum of disturbance to the carbon level and to the oxygen balance in the molten steel bath.

A novel metallized molybdenum briquette containing 30 wt. percent iron weighing about grams was produced by the novel process in Example [1. Specific gravity of the briquette was 6.1. This briquette was then added to a 16 pound iron melt held in an induction furnace under an inert atmosphere. The iron melt had a basic steel slag on the surface and this was penetrated by the briquette. The melt was held for minutes and then cast into molds. The ingots so produced were then sampled by drilling holes at different points across the diameter both at the top and bottom of the ingot. The drillings from across a given diameter were blended and analyzed for molybdenum. The results, given in Table V, show that the distribution of molybdenum was very uniform and that the recoveries were 100 percent for the reduced materials.

Table V Distribution and Recovery of Molybdenum in Iron (listing Input Molybdenum Molybdenum Concentration Recovery lron+ Contained in Casting Wt.% (Average) Molyb- Molyb- Run lron denum denum lngot No.* gm gm gm No. Top Bottom Runs 2. 6 used 30 wt.

scale addition for 30 wt. percent iron in the product, the materials were blended and briquetted. (The flow diagram for the process is shown in FIG. 1) Various quantities of reducing gas were then recycled around Zone 11 in different test runs to determine the effect of utilization of reductant or hydrogen efficiency. ln tabular form, (Table IV), the results are shown of varying the recycle ratios on the basis of complete reduction of 1 mole of molybdenum plus 30 wt. percent iron.

Table IV /1 iron briquettes; Runs 3. 5 used reduced molybdenum oxide briquettes alone.

Hydrogen Utilization Efficiency as Function of Recycle Ratio Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

l. The process of making a molybdenum briquette containing individually distinct particles of metallic molybdenum capable of penetrating steel slags comprising the steps of a. charging molybdenum oxides to a reduction furnace,

b. reducing with a gaseous reducing agent in a first stage at a temperature from about 550 to less than 650C substantially all the molybdenum trioxide in said molybdenum oxides to molybdenum dioxide,

c. reducing with a gaseous reducing agent in a second stage at a temperature between about 800 and 900C substantially all the molybdenum dioxide to metallic molybdenum,

d. crushing the metallic molybdenum, and dioxide.

e. briquetting said crushed metallic molybdenum to a density greater than about 3.5 while retaining individually distinct particles of metallic molybdenum.

2. The process of claim 1 wherein said gaseous reducing agent is selected from dissociated ammonia, carbon monoxide, hydrogen, reformed hydrocarbons and mixtures thereof, and is fed countercurrent to the molybdenum oxides and molybdenum oxide.

3. The process of claim 2 wherein said gaseous reducing agent is fed to said second stage, a first portion of gas exiting from said second stage is recycled to said second stage after condensing water therefrom, and a second portion of gas exiting from said second stage is fed to said first stage.

4. The process of claim 3 wherein said second portion of gas exiting from said second stage and fed to said first stage is at least the stoichiometric equivalent required to reduce molybdenum trioxide in said molybdenum oxides to molybdenum dioxide in said first stage.

5. The process of claim 4 wherein the molybdenum oxides are briquetted prior to charging to the reduction furnace.

6. A molybdenum product in briquette form containing less than 7 percent oxygen and having a density between about 4.5 and 7 produced by the process of claim 1 and consisting essentially of individually distinct particles of metallic molybdenum.

7. The process of making a ferromolybdenum product containing individually distinct particles of metallic molybdenum and metallic iron comprising the steps of a. charging a mixture of molybdenum oxides and iron oxides to a reduction furnace,

b. reducing with a gaseous reducing agent in a first stage at a temperature from about 550 to less than 650C substantially all the molybdenum trioxide in said mixture to molybdenum dioxide, whereby an intermediate product containing individually distinct particles of molybdenum dioxide and iron oxides is formed,

c. reducing said intermediate product with a gaseous reducing agent in a second stage at a temperature between about 800to 900C whereby the molybdenum dioxide and iron oxides in said intermediate product are substantially reduced to provide a loosely bonded mixture of individually distinct particles of metallic molybdenum and metallic iron,

d. crushing said loosely bonded mixture of metallic molybdenum and metallic iron into individual distinct particles,

e. briquetting said crushed metallic particles to a density greater than 3.5 while retaining individually distinct particles of metallic molybdenum and metallic iron.

8. The process of claim 7 wherein said gaseous reducing agent is selected from dissociated ammonia, carbon monoxide, hydrogen, reformed hydrocarbons and mixtures thereof and is fed countercurrent to said mixture and said intermediate product.

9. The process of claim 8 wherein said gaseous reducing agent is fed to said second stage, a first portion of gas exiting from said second stage is recycled to said second stage after condensing water therefrom, and a second portion of gas exiting from said second stage is fed to said first stageand is at least the stoichiometric equivalent required to reduce the molybdenum trioxide in said mixture to molybdenum dioxide in said first stage.

10. The process of claim 7 wherein said mixture is briquetted using a liquid binder prior to charging to the reduction furnace.

11. The process of claim 7 including the preliminary steps of mixing molybdenum disulfide and pyrite and roasting to provide said mixture of molybdenum oxides and iron oxides.

l2.-A ferromolybdenum product in briquette form consisting essentially of about 5 to 30 wt. percent iron and the balance molybdenum, said briquette containing less than 7 percent oxygen and having a density between about 4.5 and 7, produced by the process of claim 7 and consisting essentially of discrete particles of metallic molybdenum and metallic iron.

Claims (12)

1. THE PROCESS OF MAKING A MOLYBDENUM BRIQUETTE CONTAINING INDIVIDUALLY DISTINCT PARTICLES OF METALLIC MOLYBDENUM CAPABLE OF PENETRATING STEEL SLAGS COMPRISING THE STEPS OF A. CHARGING MOLYBDENUM OXIDES TO A REDUCTION FURNACE, B. REDUCING WITH A GASEOUS REDUCING AGENT IN A FIRST STAGE AT A TEMPERATURE FROM ABOUT 550* TO LESS THAN 650*C SUBSTANTIALLY ALL THE MOLYBDENUM TRIOXIDE IN SAID MOLYBDENUM OXIDES TO MOLYBDENUM DIOXDE, C. REDUCING WITH A GASEOUS REDUCING AGENT IN A SECOND STAGE AT A TEMPERATURE BETWEEN ABOUT 800* AND 900*C SUBSTANTIALLY ALL THE MOLYBDENUM DIOXIDE TO METALLIC MOLYBDENUM, D. CRUSHING THE METALLIC MOLYBDENUM, AND DIOXIDE. E. BRIGUETTING SAID CRUSHED METALLIC MOLYBDENUM TO A DENSITY GREATER THAN ABOUT 3.5 WHILE RETAINING INDIVIDUALLY DISTINCT PARTICLES OF METALLIC MOLYBDENUM.

2. The process of claim 1 wherein said gaseous reducing agent is selected from dissociated ammonia, carbon monoxide, hydrogen, reformed hydrocarbons and mixtures thereof, and is fed countercurrent to the molybdenum oxides and molybdenum oxide.

3. The process of claim 2 wherein said gaseous reducing agent is fed to said second stage, a first portion of gas exiting from said second stage is recycled to said second stage after condensing water therefrom, and a second portion of gas exiting from said second stage is fed to said first stage.

4. The process of claim 3 wherein said second portion of gas exiting from said second stage and fed to said first stage is at least the stoichiometric equivalent required to reduce molybdenum trioxide in said molybdenum oxides to molybdenum dioxide in said first stage.

5. The process of claim 4 wherein the molybdenum oxides are briquetted prior to charging to the reduction furnace.

6. A molybdenum product in briquette form containing less than 7 percent oxygen and having a density between about 4.5 and 7 produced by the process of claim 1 and consisting essentially of individually distinct particles of metallic molybdenum.

7. The process of making a ferromolybdenum product containing individually distinct particles of metallic molybdenum and metallic iron comprising the steps of a. charging a mixture of molybdenum oxides and iron oxides to a reduction furnace, b. reducing with a gaseous reducing agent in a first stage at a temperature from about 550* to less than 650*C substantially all the molybdenum trioxide in said mixture to molybdenum dioxide, whereby an intermediate product containing individually distinct particles of molybdenum dioxide and iron oxides is formed, c. reducing said intermediate product with a gaseous reducing agent in a second stage at a temperature between about 800*to 900*C whereby the molybdenum dioxide and iron oxides in said intermediate product are substantially reduced to provide a loosely bonded mixture of individually distinct particles of metallic molybdenum and metallic iron, d. crushing said loosely bonded mixture of metallic molybdenum and metallic iron into individual distinct particles, e. briquetting said crushed metallic particles to a density greater than 3.5 while retaining individually distinct particles of metallic molybdenum and metallic iron.

8. The process of claim 7 wherein saiD gaseous reducing agent is selected from dissociated ammonia, carbon monoxide, hydrogen, reformed hydrocarbons and mixtures thereof and is fed countercurrent to said mixture and said intermediate product.

9. The process of claim 8 wherein said gaseous reducing agent is fed to said second stage, a first portion of gas exiting from said second stage is recycled to said second stage after condensing water therefrom, and a second portion of gas exiting from said second stage is fed to said first stage and is at least the stoichiometric equivalent required to reduce the molybdenum trioxide in said mixture to molybdenum dioxide in said first stage.

10. The process of claim 7 wherein said mixture is briquetted using a liquid binder prior to charging to the reduction furnace.

11. The process of claim 7 including the preliminary steps of mixing molybdenum disulfide and pyrite and roasting to provide said mixture of molybdenum oxides and iron oxides.

12. A ferromolybdenum product in briquette form consisting essentially of about 5 to 30 wt. percent iron and the balance molybdenum, said briquette containing less than 7 percent oxygen and having a density between about 4.5 and 7, produced by the process of claim 7 and consisting essentially of discrete particles of metallic molybdenum and metallic iron.

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