Note: Descriptions are shown in the official language in which they were submitted.
Molybdenum has long been used as an alloying additive in the
production of stainless and alloy steels. ~e 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 vaporiza-
tion of the molybdenum oxide. After melt down the final adjustments to
the molybdenum level in t~.e 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 alone were
used. In addition, the use of ferromolybdenum increases the rate of
dissolution and bath homogenization and minimizes loss of 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 ha 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
proces~.
The term " lybdenum oxide" or "molybdenum oxides" as used herein-
after is defined as technical grade molybdenum trioxide (MoO3) containing
inconsequential trace impurities and minor amounts of molybdenum sesqui-
oxide (Mo203) and molybdenum dioxide (MoO2). 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 lybdenum 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 NH3 reduction. The first temperature stage is carried
- 2 - ~
' ' ""' ,....
. .
10444~
out at about 500 ~ 650C to reduce the molybdenum oxide to molybdenum
dioxide. The final redu~tion of the molybdenum dioxide to molybdenum metal
takes place in the second temperature zone at about 800 - 900C.
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 800 - 900C, reduction of the molybdenum
dioxide i9 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 500 - 600C
to lybdenum dioxide. In the second step the molybdenum dioxide is reduced
to metallic lybdenum at temperatures of between about 800 - 900C.
Since the iron is already in the metallic state no reduction thereof i8
required.
The lybdenum oxide, premixed molybdenum oxide/iron oxide, or
premixed lybdenum 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 tbe molybdenum or iron melt. As a result the product
contalns discrete or individually distinct particles of metal. The
brlquetting provides only surface bonding for ease of handling the product.
, "
, " " :: :
~.Q~g8~
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
lron may be from about 5 to about 70 or more weight percent of the briquette.
The final product contains less than about 7% by weight oxygen and is
essentially carbon free.
Specifically, the present invention enables the economical product-
tion 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
lten steel by reacting to form carbon monoxide, is diminished to below
7% in the reduction. ~inally, 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 present invention provides a method whereby molybdenum in its
higher oxidation states may be economically reduced to a metallic product
without contamination by carbonaceous materials.
The invention further provides a metallized ferromolybdenum product
of individually distinct particles loosely bonded that is suitable for
use as an alloying addi~ive in steel.
- 4 -
.
~ , - , , ,. ' , , ., . ., ' , . . .
": . : , . . .
.
' ~, , ' ' '',' , ;'': ' '',: , '
.
, ~ ' '' ' ' ' ' ; ,
The invention al~o provide~ a carbon free metallized molybdenum
product, containing less than 7% 2~ and sufficiently den~e to penetrate
steel making slags when making molybdenum alloying additions to steel.
FIG. 1 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 Figure 1, the raw materials, in this ~llustration
molybdenum oxide and iron oxide, are blended together with water and
briquetted prior to introduction into the kiln. Zone I is operated at
about 500 - 650C, 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 i8
maintained between sbout 800 - 900C. In Zone II both molybdenum dioxide
and the iron oxides in the intermediate product are reduced to provide a
metalllzed product 13 containing a minimum amount of oxygen and i8
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 i~ a surface bonded briquette of particulate metallic
lybdenum with up to about 30 weight percent or more metallic iron particles,
having a specific gravity of 4.5 - 7, essentially carbon free, and contain-
lng less than 7% oxygen.
The preferred reductant is hydrogen, which can be introduced as
hydrogen per se or in the form of dissociated ammonia. The fresbly dis-
sociated ammonia, or make-up reductant 3, is combined with a stream of
recycled gas reductant 5 and the two streams together enter the kiln as
-- 5 --
.,. . ,,, , . , , . ,, . , , i , , , , , :, ., -
', ' " ',', ', "'''~' ~"'''''', ' ' ,' '"",' ,.,
the reduction gas feed stream 9. The freshly dissociated ammonia i8~
of course, a constant 25% by volume nitrogen, and 75% 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 utiliza-
tion of available reductant for each specific molybdenum oxide/iron oxide
charge composition.
The feed gas reductant 9 enters downstream to the solid~ flow
13 and makes it way countercurrent through Zone II. A portion 15 of the
gas leaving Zone II i8 recycled around Zone II continues into Zone I to
reduce the molybdenum oxide to molybdenum dioxide. ~he 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 counter-
currently to the solids flow. In the present process, however, it i8
convenient to pass the gas countercurrent in Zone I as it exits from
Zone II. The Zone II 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 Figure 2 there is shown a plot of time versus the
percent weight 1088 at two reduction temperatures and two compositions.
The horizontal broken lines A, B and C represent theoretical weight
1088 for: A - Pure lybdenumtrioxide, B - technical grade molybdenum
trioxide, and C - technical grade molybdenum trioxide containing
sufficient lron oxide to result in a product containing 30 weight per-
cent iron.
' ' , ,' ' ,",,, , ;, ' '
, : ', , ', , ," ' -,' '' ' ' ',, .''- ', ' ",' ' "', ' ''', ''' "
. .
. " ' : '' ' ',, " ~ ' ''''; ', ' , , "
, . . . . . . . ..
Material~
The starting materials may be less than 100% pure metal oxide~ -
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 the efficiency
of the process or the yield of the 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 require-
ments.
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 a product containing both molybdenum and iron obtained by the
slmultaneous reduction of both molybdenum oxide and iron oxide rather than
by the mere blendlng of metalllc iron with a reduced molybdenum product - -
as is described in U. S. Patent No. 2,302,615. In the present invention,
the process is adaptable to meet the presence of iron oxides in terms of
thermodynamic considerations and volume of reductant supplied. The basic
parameters, which may be ad~usted 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 ga~ retuctant to make-up gas.
In orter to prevent the reoxidation of the pure metallic molybdenum
briquette once a steel alloying addition is made, it is desirable that
'" '', ., ,, ',", ", .' . ,'" ', ~ ' ' ; ' ~ '",; '; ' ,'' " ' . .,, ,, ' ' ' ~ ' ' '
~,:, , ,',,-'", ~, ',' .' ' ': ' ' . ' ' ''
" ,,, j , , : ,
, .. . . .. . .
""" "~ "~""~w~fr~i~if; ~
the molybdenum be dissolved as quickly as possible in the ~teel melt.
To accomplish this quick dissolution, a quantity of iron is introduced
with the molybdenum into the steel melt. Dissolution in the ~teel melt
is relatively rapid since the novel product of this invention is a
loosely surface bonded briquette of discrete pa~ticles of metallic
molybdenum and iron.
In the final metallized ferromolybdenum alloying agent, a quantity
of iron in excess of 15% has been found to be beneficial. Specifically,
an iron concentration in excess of 15% in the briquette product has
the effect of promoting rapid dissolution of molybdenum in the steel melt
and contributing to a very hlgh 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 i9 the avoidance of
both reoxitation and 1098 of lybdenum in the slag, and the ~ettling
out of heavy refractory molybdenum bearing compounds at the bottom of
the vesRel which might cause problems with subsequent heats.
In carrying out the process of the present invention, we have found
that several novel products may be produced which are particularly u~eful
as alloying additions in the preparation of alloy steels. The present
process is adaptable to provide for the production of these various
products. ~or example, the temperature and gas reductant levels may be
altered to provide for the reduction of 100% molybdenum oxide starting
material or mixture of molybdenum oxide and iron or iron oxides in any
desired proportions. A practical limlt is up to 70% iron oxide in the
~tartlng material. The reduction may al~o be carried ou~ in rotary
~- ' ,
,
,: " ",., ,:,, ~,,: ,~,., . ' '
lf;~ 4~
kilns, belt furnaces, or fluidized beds, as long as the temperature
stages and gas recycling are maintained. We have found that the presence
of a 30 weight percent iron addition decreases the reduction time relative
to molybdenum oxide alone by 40% with consequent advantages in reducing
the size of the equipment.
In Zone I the molybdenum oxide is reduced to molybdenum dioxide
between about 500 - 650C. At temperatures in excess of 650C molybdenum
trioxide is known to volatili~e. For this reason the first stage of the
process is carried out below 650C. 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 sta8e requires that the reaction be carried out at higher
temperatures than in the first stage. The greatest improvement occurs
when the temperature i9 raised to at least 800C with less significant
benefit occurring above 900C. In addition, increasing the temperature
has a marked effect on the rate of reduction, the time required being
reduced by a factor of three when the temperature is raised from 800 to
900C. ~igure 2 illustrates this. Equipment design considerations and
energy requirements preclude using much higher temperatures, 80 that ~ -
800 - 900C is con~idered 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 the process of the present
invention. We have been able to produce a ferromolybdenum product from
iron and molybdenum oxides without fuslng at the high temperatures used
ln conventional ferromolybdenum production. Instead, we are able to
co-reduce the oxides at temperatures not in excess of 900C. ~ -
_ g ~ .-
,, ' ,'' ' ' ,' ' ';'. ,', " ', ~ "',, : "" ' ,'
lr3~
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. We prefer that
the hydrogen source be cracked ammonia because of itq low cost. The feed
gas 9, (recycled plus make-up), will be about 50% H2/50% N2 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 II 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 stoichiometrics.
The Zone I reaction is not appreciably altered by the partial
pressure of hydrogen to partial pressure of water vapor ratio, and no
ad~u~tment in the stoichiometric calculations need be made with respect
to the reductant requirementq for Zone I. Therefore, for maximum utiliza-
tion of reductant only enough reductant to complete the molybdenum tri-
oxide reduction to molybdenum dioxide i~ allowed to enter countercurrent-
ly into Zone I. The remaining gas 15 from Zone II is recycled through
a conden~er to re ve the water therefrom and feed 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
reductlon rate 18 negative in Zone II.
The Novel Metallized Products
The preferred product for alloying of ferrous metals is produced
-- 10 --
" ,: ' ~ , " '' , ,, ,, , , .," '
,, , , , , ,, , , , : , ,
,, , " ~, , ; ,, .
4~36
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
0-30 weight %. The molybdenum oxide and iron oxide are co-reduced to pro-
duce the desired metallized product. While 30 weight ~ is the prefer~ed
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% by weight oxygen and be essentially carbon free.
We prefer that the product be a briquetted mixture of co-reduced
metallic particles of molybdenum 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 u~ed
directly a6 an alloying agent.
Finally, the process is adaptable to be used in producing a
metallized ferromolybdenum product from the mixed sulfides of lybdenum
and iron. In a prior roasting step, the MoS2 and FeS2 (pyrite) may be
co-roasted to yield mixed oxides which are then briquetted and charged
directly in Zone I of the furnace of the novel process. This additional
step in the process is particularly attractive from an economic stand-
point because the metal sulfides are generally the least expensive source
of lybdenum and iron. The process produces a metallized ferromolybdenum
product from these crude raw materials with essentially complete utiliza-
tion of reductant.
We have found in practicing the process of the present invention
that the phys1cal form of oxide charge is important. Preferably the
~tarting material~ wlll be particulates in the size range from about --
mlnu~ 20 to about mlnus 325 mesh. Table II below presents a typical size
- . . . .. . . . ... . .. .. . .
,: , " , ; .,, ., "' ,. , ' .,,, , . :, , ,
distribution range for technical grade molybdenum trioxide, Iron oxide
particles should be within same general slze range. The reduction steps,
for example, may be carried out in shallow beds of oxide po~ders but
unreacted core and handling problems may decrease the gas utilization
efficiency of the process. We, therefore, prefer that the molybdenum
and iron oxides be blended with water and briquetted prior to reduction.
Around 3% 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 80 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, we
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 entlrely 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% of the reduced molybdenum in the
briquette i8 recovered in the steel rather than a significant proportion
being lo~t in the slag.
- 12 -
,, ,:, ,,, ,,,, , " ",, ,,, , ', ,,
,';, " , ,', ,, ,, '' ', ;,' ' ' ', , , , :
,, , '" ', ' ,: , , ~ , , , , , : , ,
, ~, ",, ,': ,; : ' ' ' ' '
.. . . . . .
, -, ,, ' , ,'" , ' ,
. .
lt~ 4~
The metallized ferromolybdenum product need not be 100% reduced
for use in the steel alloying process. With almost 100% 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
0-2% by weight.
Without limiting the above described process, the following examples
are illustrative of the features of the inventlon.
Example I
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 about 500C and about 900C.
The assay and size distributions of the molybdenum oxide are shown in
Tables I and II. The speed of the moving grate kiln is set 80 that the
briquettes will be totally reduced during the passage of the molybdenum
oxide therethrough. This usually takes place when the oxide ha been in
the hot zones for 4-5 hours.
! Table I
Assay of Molybdenum Oxide --
Molybdenum Iron Copper Lead Sulfur Oxygen
wt. % wt. % wt. % wt.% wt. % wt. %
58-62 1 0.4-0.8 0.015-0.030 0.04-0.2 29-31
- 13 -
,, ~, . ,, ,, ',, ,,, :,
,
Table II
Size Distribution of Mol~bdenum Oxide
Screen Size % Retained
-20 + 30 2.14
-30 + 60 17.38
-60 + 80 18.56
-80 + 120 22.30
-120 + 140 10.53
-140 + 170 3.24
-170 + 230 8.49
-230 + 270 2.32
-270 + 325 7.08
-325 7.96
The reducing gas, dissociated ammonia, is passed countercurrent
to the solids flow. The feed stream of dissociated ammonia enter~ at a
rate of around two moles ammonia for each le of molybdenum to be reduced.
After the reductant passes through Zone II at about 900C, a bleed stream
removes all but one le of hydrogen for each mole of molybdenum trioxide
to be reduced according to the reaction
MoO3 + H2 ~ MO2 + H20 (1)
The remaining reductant from Zone II is recycled through a condenser
to remove the water and then back into the feed stream. The recycle portion
brlngs the overall feed composition to 50~ H2/50% N2. In the process
approximately ten les H2 + N2 are recycled when the reaction reaches
eteady 8tate. This results in a hydrogen efficiency approaching 100%
tl8counting leakage losses.
The molybtenum oxide i~ reduced completely in Zone I to molybdenum
dioxide whlch 18 further reduced to lybdenum metal in Zone II. Oxygen
' '- ' ' .
, ,
f~
in the final product i9 no more than 1-2% aY determined by the ~oTnparison
of the actual weight loss with that calculated from the lybdenum content.
It is calculated that no more than about 0.32 lb. of NH3 i~ used for
every pound of molybdenum metal produced. This compares with 0.83 lb. NH3/lb.
molybdenum with no recycling of hydrogen. The rate of weight 1088 for
Examples I and II are shown in Figure 2. For comparison, the rate of
weight loss is shown for the same materials at about 800C. The expected
weight loss is also shown (broken line A) based on an initial molybdenum
content of 60 wt.%, as analyzed for this particular batch of material, and
10 assuming that the only oxygen present was as molybdenum trioxide. It can
be seen that at about 900C 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.
l~xale II
Co-Reduction of Iron Oxides and Molybdenum Oxide -~
The process of Example I was followed butwithmillscale blended
and briquetted with the lybdenum oxide such that ~he product would
contain 30 wt.% iron after reduction. (Millscale ~ PeO 60-70 wt.%,
Fe203 25-30 wt.%, Fe304 5-10 wt.%, by x-ray analysis overall composition
20 FeOl 2 by hydrogen reduction). The briquettes measured about 1/2" in
diameter and 1/2" long and weighet 5 grams each. Furnace temperature in
Zone I remained at about 600C but the dissociated ammonia feed was
increased to 2.6 les per mole molybdenum. Again one mole N2 per le
molybdenum was allowed to proceed from Zone II into Zone I and the
remaining 9.8 moles N2 + H3 (at steady state) were recycled through the
contenser and lnto the dissociated ammonia feed stream. Overall feed
composition ~recycle plus make-up) was 56.4% N2t43.6% H2 and 0.42 lb. of
a~onia was u~et for every pound of molybdenum metal reduced. The
-- 15 --
.
'""' '' ' '."' "'" ,"'' ',,' , ', ,",'' ~' ,'.,~ ' ',' ' ', ';''"'' ', ' " ' ' ' . ,', ' '' ' ', ' ' , '
' ' , ',, ' ' ' ' ' ' " , ''' '" ,' , ,' " ', ' ,,, " , ' ' ,, , ' : " . . . .
... .-.. . .. . . . ..
' ', ,,' ' , ' ', '' ,'' ', " '", ', ': '
densities of various process materials are shown in Table III.
Table III
Density of Process Materials
Material Specific Gravity
Molybdenum Oxide (technical grade
molybdenum trioxide) 2.2
Millscale l.9
Green Pellet 3.6
'MoO2' Pellet 2.3
Mo -Pe Pellet (30 wt.%) 2.3
Mo -Pe Powder (30 wt.%~ 1.7
Recompacted Mo - Fe (30 wt,%) 4.5
Recompacted Mo 4.3 to 7.2
Example III
Effect of Recycle Ratio around Zone II on Hydrogen Efficiency
Using the process of Example II, again wlth the millscale addition
for 30 wt.% iron in the product, the materials were blended and briquetted.
(The flow diagram for the process is shown in Pigure 1). Various quantities
of reducing gas were then recycled around Zone II in different test runs
to determine the effect of utilization of reductant or hydrogen efficiency.
In tabular form (Table IV), the results are shown of varying the recycle
ratios on the basis of complete reduction of one mole of molybdenum plus
30 wt.~ iron. --
- 16 -
.. . .. .... .. . . . . .
, "". ,~ , , ,;, ,, , . :
,, , , . ~ ,, ,, ",:, : , . . . .
,, " ,, , " , : ,, . " ,.... .... . .... .. ..
$
Table IV
Hydrogen Utilization Efficiency as ~unction of Recycle Ratio
Feed to ~eed Hydrogen Overall ~eed
Recycle Zone I Make-Up Efficiency Compo~ition
N2~H2 N2+H2 H2 NH3 Moles % %N2t%H2
Moles Moles Moles
0 8.0 5.27 5.43 47.7 34/66
3.5~ 5.0 2.0 4.00 64.8 40/60
7.30 3.0 1.5 3.00 86.3 50/50
9.80 2.3 1.0 2.59 100.0 56.4/43.6
Example IV - -
Recovery of Ferro lybdenum Product in Steel
The ob~ect of the ferromolybdenum product i8 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 lten steel bath.
A novel metallized molybdenum briquette containing 30 wt.% iron
weighing about 15 grams was produced by the novel procesR in Example II.
Specific gravity of the briquette was 6.1. This briquette was then added
to a 16 pound iron melt held in an inductlon 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 30 minutes and
then cast into lds. The ingots 80 produced were then Rampled by drilling
holes at different points across the diame~er 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
- 17 -
. .
l'3'~ 5
distribution of molybdenum was very uniform and that the recoveries were
100% for the reduced materials.
Table V
Distribution and Recovery of Molybdenum in Iron Ca~tin~s
Input Output
Molybdenum Molybdenum
Concentration Recovery
Iron + Contained in Casting Wt.% (Average)
Molyb- Molyb-
Run Iron denum denum Ingot
No.* gm gm gm No. Top Bottom %
_
2 7300 25.79 15.52 (1) 0.202 0.210 99
(2) 0.209 0.208
3 7300 17.8 15.52 (1) 0.209 0.209 100
(2) 0.209 0.208
7300 17.54 14.29 (1) 0.194 0.199 101
6 7300 34.27 21.23 (1) 0.289 0.288 100
* Runs 2, 6 used 30 wt.% iron briquet~es; Runs 3, 5 used reduced
lybdenum oxide briquettes alone
Without further analysis, the foregoing will 80 fully reveal tbe
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 ~hould and are intended to be comprehended within the meaning
ant range of equlvalence of the following claims.
~ 18 ~
r - ; . ,. ~ ; .
, , ' ' .
, , , ' ,, , , ,, ' ' '
~, . :, . . . .
,
, " / , , , ", ., ~ :
