United States Patent Office 3,376,103
Patented Apr. 2, 1968
1 2
mercial product. In instances where a neutral alkali metal
salt was attempted to be used in the roasting of ferrophosphorus
such as sodium chloride, the vanadium was not
sufficiently solubilized to enable the vanadium values to
5 be recovered in economic yields, and the vanadium was
largely retained in the ferrophosphorus upon leaching the
roast.
In accordance with the present invention, it is possible
to roast the ferrophosphorus and oxidize the vanadium
10 values to a soluble state while controlling the solubilization
of phosphorus at a practical level. As a result, the
roast may be leached with an aqueous leaching medium
to thereby provide a vanadium bearing leach liquor which
contains a sufficiently high ratio of vanadium values to
15 phosphorus values to allow the recovery of a vanadium
product of commerce of high purity without having to
resort to uneconomic practices. The invention also provides
improved processes for cooling the ferrophosphorus
during the roast to control the roasting temperature, and
20 for quenching the roast so as to assure faster percolation
leaching than was practical heretofore. Thus, the invention
provides for the first time an entirely satisfactory
process for solubilizing and recovering vanadium values
contained in vanadium bearing materials such as ferro-
25 phosphorus.
It is an object of the present invention to provide an
improved process for roasting vanadium bearing materials
and for recovering vanadium values from the roasted
material.
It is still a further object to provide an improved process
for roasting vanadium bearing ferrophosphorus and
for recovering vanadium values from the roasted ferrophosphorus.
It is still a further object to provide an improved proc35
ess for maintaining a desired roasting temperature in the
roasting of ferrophosphorus and other vanadium bearing
materials.
It is still a further object to provide an improved process
for quenching roasted vanadium bearing materials
40 such as ferrophosphorus whereby the quenched roast may
be percolation leached at fast flow rates to dissolve and
recover in the leach liquor substantially all of the vanadium
values present in the ore.
It is still a further object to provide an improved proc45
ess for reducing the amount of phosphorus solubilized
during the roasting of vanadium bearing materials such
as ferrophosphorus.
Still other objects and advantages of the invention will
50 be apparent to those skilled in the art upon reference to
the following detailed description and the examples.
In accordance with one important aspect of the present
invention, it has been discovered that if a vanadium
:bearing ore such as ferrophosphorus is roasted under oxi-
55 dizing conditions over a plurality of roasting stages in the
presence of a substantially neutral alkali metal salt, the
vanadium values are solubilized and may he recovered
in high yield and the solubilization of phosphorus and
other undesirable impurities is controlled within practi-
60 cal limits.
The ferrophosphorus or other ore as received usually
is in the form of lumps of substantial size and it should be
ground to a fine particle size prior to roasting. Usually, it
is preferred that the ferrophosphorus be reduced to a
65 particle size of about -48 to -400 mesh, or to abont
-100 to -150 mesh or finer for better results from the
standpoint of roasting. In many instances, a particle size
of about -48 to -84 mesh is satisfactory and presents
70 fewer handling problems. One preferred method of reducing
the ore to the ultimate particle size is by means
of a hammer mill.
3,376,103
PROCESS FOR ROASTING VANADIUM ORES
Angus V. Henric!mon and Jahn A. Hermann, Golden, and
Adolph E. Meyer, Wheatridge, Colo., assignors to KerrMcGee
Corporation, a corporation of Delaware
No Drawing. Filed Mar. 9, 1964, Ser. No. 350,573
20 Claims. (CI. 23-15)
ABSTRACT OF THE DISCLOSURE
Vanadium values are recovered from vanadium bearing
ores by a novel process including a plurality of roasting
stages in the presence of at least one substantially
neutral salt of an alkali metal selected from the group
consisting of sodium and potassium and a strong mineral
acid. The ore is roasted under oxidizing conditions until
the vanadium values are solubilized, and then the roasted
ore is leached with an aqueous medium to produce an
aqueous leach liquor containing the solubilized vanadium
values. Thereafter, the vanadium values are recovered
from the leach liquor.
This invention broadly relates to the recovery of vanadium
values from vanadium bearing materials. In one
of its more specific aspects, the invention further relates
to an improved process for roasting vanadium bearing
materials.
The invention will be described and illustrated hereinafter
with specific reference to a process for recovering 30
vanadium values from vanadium bearing ferrophosphorus.
However, it is understood that the invention may be useful
in the recovery of vanadium from other vanadium
bearing ores or materials.
Ferrophosphorus usually contains extraneous metal
values such as vanadium, chromium, titanium, nickel and
manganese. For instance, an average analysis for one
ferrophosphorus of commerce is 27.5% phosphorus,
7.07% vanadium, 4.67% chromium, 1.23% titanium,
1.36% nickel, 0.2% manganese, 0.4% silicon and the remainder
iron. Ferrophosphorus is available in large quantities
at low cost, and it would be a convenient source
material for relatively expensive vanadium provided an
economic process for obtaining the vanadium in high
purity were available.
Ferrophosphorus is a reduced product and it is necessary
to subject it to an oxidizing roast in order to oxidize
the vanadium values to a water-soluble state. As is well
known, large quantities of contaminating substances such
as phosphorus are rendered soluble by conventional roasting
procedures in instances where the roast is sufficiently
vigorous to result in the solubiiization of vanadium values
and the contaminants appear in the leach solution and in
turn in the vanadium product precipitated therefrom.
Phosphorus is an extremely deleterious contaminant and
a vanadium concentrate is rendered useless as a commercial
vanadium product in instances where the phosphorus
exceeds more than about 0.05 %. It is therefore obvious
that the control of phosphorus solubilization during the
roast is very important.
In accordance with the prior art processes, ferrophosphorus
was roasted for a sufficient period of time to solubilize
the vanadium with an alkaline alkali salt such as
sodium carbonate or sodium hydroxide as an essential
constituent of the roast. However, under these conditions
the solubilization of the vanadium also resulted in the
solubilization of other substances present in the ferrophosphorus,
such as large amounts of phosphorus, chromium,
etc., and it was difficult to recover the vanadium
values in sufficient purity for sale as a high purity com3,376,103
3
The alkali metal salt to be roasted with the ferrophosphorus
maybe added to the ore at a suitable stage.
Preferably, the salt as about ~30 mesh material is added
to the me following reduction. to the ultimate particle
size such as-100 mesh.
The mixture of ore and alkali metal salt may be subjected
to an oxidizing primary roast at a temperature
sufficiently low to prevent melting of the ferrophosphorus
or a large amount of sintering. For best results, the primary
roast is conducted in the presence of an oxidizing
elemental· oxygen-containing gas such as air at a temperature
of approximately 650-750° C. The roast may be
conducted over a period of approximately 1 to 4 hours,
although longer or shorter times may be effective in some
instances depending upon the nature of the ore such as
from 30 minutes to 8 hours. Thereafter, the hot primary
roast may be cooled to a temperature sufficiently low
for the ore to be crushed as it agglomerates to some extent
during the roast. The cooling or quenching step may
be accomplished by allowing the hot roast to cool in air
at ambient temperature, air or steam may be passed over
the hot roast, or it may be sprayed with sufficient water to
allow cooling without actually immersing in water. The
hot roast may be quenched by submersing in water but
this is not usually desired.
The cooled ore may be crushed or ground to a particle
size not greater than about -3 mesh and preferably not
greater than -10 mesh, or to a smaller particle size such
as about -48 to -400 mesh. Also, an additional quantity
of the alkali metal saltmay be added and mixed with
the ore, and preferably prior to crushing so that the salt
it intimately mixed throughout the ore and ground therewith
to provide a fine particle size. For best results, the
ore should be at a temperature not greater than about
100-200° C.during the crushing step following theprimary
roast. In some instances, all of the alkali metal salt
may be added prior to the primary roast and a further
addition prior to the secondary roast is not necessary.
The ferrophosphorus ore from the primary roast, and
in the presence of the alkali metal salt, may be subjected
to a secondary roast under oxidizing conditions at a temperature
of approximately600~800° C. The secondary
roast may 'be conducted in the presence of an elemental
oxygen.,containinggas such as air over a period of approximately
1 to 4 hours, but longer or shorter periods
may be satisfactory such as about 30 minutes to 8 hours.
The ore may be air or steam cooled following the secondary
roast, or it may be quenched by means of a water
spray wherein water is sprayed on the ore in sufficient
quantities to reduce its temperature without immersing
the roasted are in a pool of water. The hot roasted Ore
may be quenched by immersing in water so as to fracture
the agglomerates but this is not necessary and usually is
not preferred when a percolation leaching step is used
for leaching the vanadium values from the roasted ore.
In instances where the ore is to be percolation leached,
the hot secondary roast is air or steam cooled, or sprayed
with a controlled amount of water which is preferably
insufficient to permanently wet the ore to thereby reduce
the temperature to a value not greater than about 1002000
C. Thereafter, the cooled roasted ore is percolation
leached with water to thereby produce a leach solution
containing the solubilized vanadium values and greatly
reduced amounts of ,phosphorus and other undesirable
impurities.
Prior art agitation leaching with water may be used
when this is desirable for recovering the solubilized vanadium
from the roast,and only about one to two hours
of agitation leaching is necessary in most instances. The
leach liquor from an agitation leach usually is not as
clear as that obtained with percolation leaching and clarification
may be necessary in some instances.
In instances where a percolation leach is practiced, it
is preferably conducted in a plurality of leach vessels
with the aqueous leach liquor advancing over at least
4
three-four stages to thereby produce a very concentrated
leach liquor. Usually only one-two tons or less of water
per ton of roasted are is necessary for leaching and there
is no need for clarifiers, thickeners, etc. in most instances.
5 When the preferred quench procedure of the invention
is used in combination with percolation leaching, it is
possible to obtain flow rates of 100-200 gallons per squale
foot per day or higher. Usually, the flow of leach liquor
through the ore,in the preferred percolation leach process
10 is restricted to provide a total 'fesidence time upon advancing
through fOUf leach cycles Of stages of approximately
one day and thereby assure extraction of almost
the entire solubilized vanadium content of the ore~ It is
preferred that a submerged leach be conducted, although
15 a trickle leach of the are is possible. The particle size of
the roast averages about one-half inch in diameter when
the preferred quenching process is effected, and the agglomerates
are porous and cellular. As a result, particle
size is not important and much larger particles than one-
20 half inch may be leached when this is desirable, or
smaller particles down to the point where they become
sufficiently small to restrict the flow of the leach liquor.
The amount of alkali metal salt which is added to the
ore may be varied over wide ranges. In most instances
25 and especially when the ore is ferrophosphorus, it is preferred
that the total amount of alkali metal salt which is
added be approximately 0.35 to 2 parts by weight for
each part by weight of ore. For best results, it is usually
preferred that all of the salt be added prior to the pri-
30 mary roast, but if desired the alkali metal salt may also
be added in two stages with about 5-95% of the salt being
added prior to the primary rosat and approximately
95-5% being added prior to the secondary roast. When
the ferrophosphorus contains about 7% vanadium, then
35 a total of about 0.7 part by weight of the alkali metal
salt per part by weight of ferrophosphorus is used for
best results although this may vary somewhat when the
vanadium content of the ferrophosphorus varies. For instance,
when sodium chloride is used as the alkali metal
40 salt it is preferred that the weight ratio of sodiumchloc
ride to vanadium vary between 5: 1 and 2: 1, and preferably
is about 10; l.
The nature of the alkali metal salt which may be used
in practicing thep resent invention is of importance. For
45 instance, an amount effective to solubilize phosphorus of
alkaline alkali metal salts such as the alkali metal carbonates,
hydroxides, etc. should not be used, and only
substantially neutral alkali metal salts are satisfactory.
The preferred alkali metals are sodium and potassium,
50 and the salts are usually substantially neutral salts of
strong mineral acids such as sulfates, halides including
chlorides, etc. Sodium chloride is much preferred.
It is very desirable that the ore be reduced to a fine
particle size in instances where a maximum recovery of
55 the vanadium is desired. Usually, for a commercial process
· it is preferred that the particle size be not greater
than-48 mesh and preferably not greater than -84
mesh, or for best results -80 to-lOa mesh or finer, at
the time of first 'subjecting the ore to the primary roast.
60 Also, for best results the added alkali metal salt should
be intimately and uniformly mixed with the finely divided
ore. It is also very desirable that the agglomerated ore
from the primary roast be subjected to a crushing .or
grinding step prior to the secondary roast to assure that
65 the interior of the agglomerates is subjected to an oxidiz-'
ing roast in the presence of an additional quantity of
the alkali metal salt. Otherwise, maximum recovery of
vanadium is not obtained in most instances.
Ferrophosphorus is a reduced product and it is essen-
70 tial that it be subjected to an oxidizing roast. In most
instances, air is passed over the ore during the roast in
quantities sufficient to assure an oxidizing atmosphere.
This. also has the desirable effect of cooling the highly
exothermic reactants and air at ambient temperature may
75 be supplied in a volume sufficient to assure that the. de./
3,376,103
6
tained upon leaching ferrophosphorus roasted in accordance
with the present invention may be recovered by any
convenient prior art procedure. While not limited thereto,
one very s'atisfactory method of recovering the vanadium
5 values as a commercial product involves precipitating ammonium
metavanadate from the leach liquor by addition
of ammonium chloride. The resultant impure ammonium
metavanadate may be purified by digestion in the presence
of a small amount of ·base such as sodium hydroxide
10 or carbonate, and then reprecipitating ammonium metavanadate
from the resultant solution by addition of a
further quantity of ammonium chloride. The purified ammonium
metavanadate may be dried, decomposed by
heating to vanadium pentoxide, which in turn may be
15 fused to black cake. The above procedure for recovering
the vanadium values as a commercial vanadium product
is only exemplary, and numerous other methods are well
known to the art and may be used.
The foregoing detailed description and the following
20 specific examples are for purposes of iIlustration only and
are not intended as being limiting to the spirit or scope
of the appended claims.
Example I
Ferrophosphorus containing 27.5% P, 7.07% V,4.67%
Cr, 1.23% Ti, 1.36% Ni, 0.2% Mn, 0.4% Si and the
remainder Fe, by weight, and having a particle size of
approximately 2 to 3 inches was fed to a gyratory where
the particle size was reduced to about llh inches. The
30 gyratory discharge was fed to a standard cone crusher
which in turn discharged material to a vibrating screen
fitted with a 14-inch aperture screen. The screen oversize
was fed to a Pennsylvania impactor where it was
reduced to a size passing the screen, and the screen under-
35 size, 14-inch material, was used as ball mill feed. Further
grinding was in a Hardinge airswept mill using a 270 M
screen specification as a control. A screen analysis of
the output indicated that the -270 M fraction was about
75% and the +150 M fraction was about 8%. Sodium
40 chloride in an amount of 0.5 pound per pound of ferrophosphorus
was mixed with the output from the Hardinge
mill and the mixture passed to a rod mill where it was
gound to -100 mesh.
The mixture of ground ore and salt was fed to a
45 primary roaster and subjected to a primary oxidizing
roast at a temperature of 650-725° C. until a sample
of the roasted ore when crushed and immersed in a small
amount of water resulted in a pH value of 6.5 in the
water. This required a roast of about four hours. Then,
50 the calcine was cooled from the roasting temperature to
100° C. by passing air at ambient temperature thereover.
It was also found that a satisfactory and more
rapid quench could be achieved by spraying droplets or
a mist of water on the hot roasted ore in quantities suffi-
55 cient to cool the ore without immersing it in liquid water.
The cooled ore from the primary roaster was ground
to -100 mesh in a ball mill. Prior to feeding the are to
the ball mill, 0.25 lb. of sodium chloride per pound of
ferrophosphoms was 'added and the mixture fed to the
60 ball mill for the purpose of assuring a desired particle
size and thorough mixing of the salt with the roasted ore.
The output from the ball mill was fed to a secondary
roaster and subjected to a secondary oxidizing roast at a
temperature of 650-725° C. The secondary roast was con-
65 tinued for a period ohime sufficient to result in· a pH of
8 when a sample of the calcine was crushed and quenched
in a small amount of water. The secondary roast required
about three hours. In both the primary and secondary
roasts an oxidizing atmosphere was provided and
70 the ore was cooled during the exothermic reaction by
passing excess air at ambient temperature over the roasting
ore.
The hot calcine from the secondary roaster was cooled
to below 100° C. bypassing air thereover. It was also
75 found that it was possible to spray droplets or a mist
5
sired temperature range is maintained. In such instances,
a much larger quantity of air is supplied than is normally
necessary to assure an oxidizing atmosphere.
The use of air in excess for cooling purposes may be
undesirable in instances where the alkali metal salt is
a chloride and it is desired to recover a maximum amount
of gaseous hydrochloric acid from the roaster gasses. It
has been discovered that excess elemental oxygen and
low moisture content in the roaster gases reduce the hydrochloric
acid content and thus are detrimental to the
percent yield of hydrochloric acid. In one important variant
of the invention water may be sprayed or added by
other suitable method to the roasting ore during at least
a portion of the roasting cycle. The added water cools
the ore and thereby aids in maintaining the desired temperature
range and this is especially desirable during the
highly exothermic stages of the roast. The added water
also reduces the free chlorine content and assures a maximum
content of hydrochloric acid in the roaster gases
and the yield of gaseous hydrochloric acid may be increased
substantially. Addtionally, less cooling air is
needed to maintain the desired temperature range and
the volume of gases withdrawn from the roasters is much
less and may be scrubbed for recovery of gaseous hydrochloric
acid and other constituents such as vanadium 25
values much easier. The water may be added at the rate
of about 0.1-2 pounds per pound of ore and preferably
0.5-1.5 pounds per pound of ore.
In still another important variant of the invention,
magnesium oxide and/or calcium oxide, or magnesium
or calcium salts which are capable of yielding these substances
in the roaster, may be added to the ore at some
stage prior to a roasting step to further reduce the amount
of phosphorus in the leach liquor. Only a small amount
of these substances should be added, such as up to 0.1
pound of magnesium or calcium oxide or the equivalent
per pound of ore. It is preferred that the magnesium oxide
or calcium oxide be added prior to the second roast in
most instances, although it may have some beneficial
effect when added prior to the first roast. In some instances,
better results may be obtained by adding small
amounts to both the primary and secondary roasts.
The time periods for the primary and secondary roasts
may vary over wide ranges. However, it is preferred
that the primary roast be conducted for such a period of
time as is required to assure a pH value of not less than
3.3 and, for better results, a pH value of 5.5 or higher
upon quenching or leaching a portion of the crushed
roasted ore in water. Normally, the primary roast is yellow
to brownish yellow in color at this stage, and the
pH value of the quench or leach water will be greater
than 3.3, and preferably greater than 5.5 with no ferrous
iron or substantially no ferrous iron being present in the
roast. Even better results are obtained when the pH value
is at least 6.0, and best results at pH values of about 6.6
to 6.9 or higher. In carrying out this test, it is necessary
that the ferrophosphorus from the primary roast be sufficiently
finely divided to assure that the quenching or
leaching water reaches the interior of the particles as
otherwise a true test is not obtained. The secondary roast
should be conducted for such a period of time as is necessary
to provide a pH of at least 6.5 to 7.0 or higher
in a small amount of water used to quench or leach a
portion of the crushed roasted ore, and best results ani
obtained when the pH is 7.5 to 8.0 or higher. When the
primary and secondary roasts are conducted as described
above, then a maximum amount of the vanadium is
solubilized and a minimum amount of undesirable impurities
such as phosphorus.
In some instances, it is desirable to conduct at least
a portion of the roast under conditions where added
water is not present in the roaster gases in contact with
the ore. This seems to aid in the solubilization of' a
maximum amount of vanadium.
The vanadium values present in the leach liquor ob3,376,103
15
8
About 1.0-1.5 lbs. of water for each pound of ferrophosphorus
is sprayed •on the ore on the first two trays
of the roaster and it results in adequate cooling when
sufficient atmospheric air is supplied thereto to result in
5 an oxidizing atmosphere. This reduced the output of gases
from the roaster to a level whereby it was easy to scrub
the gaseous hydrochloric acid content without any difficulty.
Also, unexpectedly there is a sharp increase in the
total amount of hydrochloric acid in the roaster gases.
10 Thus, this procedure enables the preparation of additional
hydrochloric acid which may be utilized for the preparation
of ammonium chloride for the precipitation of ammonium
metavanadate.
What is claimed is:
1. A process for recovering vanadium values from
vanadium bearing ore comprising the steps of roasting
under oxidizing conditions a mixture consisting essentially
of vanadium bearing ore and at least one· substantially
neutral salt· of an alkali metal selected from the group
20 consisting of sodium and potassium and a strong mineral
acid, mixing an additional quantity of the said alkali metal
salt with the roasted ore, roasting the resulting mixture
consisting essentially of the roasted ore and the said
alkali metal salt under oxidizing conditions, the vanadium
25 bearing ore being roasted in the foregoing roasting steps
under oxidizing conditions until vanadium values contained
therein are solubilized, leaching the roasted ore
with an aqueous medium to produce an aqueous leach
liquor containing solubilizide vanadium· values, and re-
30 covering vanadium values from the leach liquor.
2. The process of claim 1 wherein the vanadium bearing
ore is vanadium bearing ferrophosphorus.
3. The process of claim 2 wherein the alkali metal
salt is sodium chloride.
4. A process for recovering vanadium values from
vanadium bearing ore-comprising the steps of roasting
under oxidizing conditions a mixture consisting essentially
of vanadium bearing. ore and at least one substantially
neutral salt of an alkali· metal selected from the group
40 consisting of sodium and potassium and a strong mineral
acid, reducing the particle size of the roasted ore, thereafter
subjecting the roasted ore toa second roast under
oxidizing conditions in the presence of a quantity of the
said alkali metal salt, the vanadium bearing ore being
roasted in the foregoing roasting steps under oxidizing
45 conditions until vanadium values contained therein are
solubilized, leaching the roasted ore with ,an aqueous
medium to produce an aqueous leach liquor containing
solubilized vanadium values, and recovering vanadium
values from the leach liquor.
50 5. The process of claim 4 wherein the vanadium· bearing
ore is vanadium bearing ferrophosphorus.
6. The process of claim 5 wherein the alkali metal salt
is sodium chloride.
7. A process for recovering vanadium values from
55 vanadium bearing ore comprising the steps of roasting
under oxidizing conditions a mixture consisting essentially
of the vanadium bearing ore and at least one substantially
neutral salt of an alkali metal selected from the group
consisting of sodium and potassium and a strong mineral
60 acid, adding an additional quantity of the said alkali metal
saItto the roasted ore, reducing the particle size of the
roasted ore, thereafter subjecting· a mixture consisting
essentially of the roasted ore and the said alkali metal,
65 saIt to a second rOast under oxidizing conditions, the
vanadium bearing are being roasted in the foregoing
roasting steps under oxidizing conditions until vanadium
values contained therein are solubilized, leachi.ng the
roasted ore with an aqueous medium to produce an aque-
70 ous leach liquor containing solubilized vanadium values,
and recovering vanadium values from the leach liquor.
S. A process for recovering vanadium values from
vanadium bearing ferrophosphorus comprising the steps
of roasting under oxidizing conditions in the presence of
75 an elemental oxygen-containing gas a mixture consisting
7
of water on the hot ore and thereby achieve a faster rate
of .cooling without adversely affecting the particle size
of the roasted ore. When the ore was thus cooled, the particle
size was substantially the same as that of the hot
roasted ore leaving the secondary roaster.
Four vats arranged in series were filled with the cooled
ore from the secondary roaster and then the ore was
percolation leached with water using about one ton of
water per ton of ore. The leach liquor was advanced
through the four vats in series at a rate sufficient to assure
contact with the ore over a 24 hour period. Also,
the process was operated continuously with a fresh vat
of ore being placed on stream in contact with the most
concentrated leach liquor when the first vat in the series
was completely leached.
Roasting and percolation .leaching in accordance with
this example resulted in the solubilization of 91-92%
of the original vanadium content of the ferrophosphorus
and the recovery of substantially all of the solubilized
vanadium. It was not necessary to crush the roasted ore
to a smaller -particle size. to achieve as complete a recovery
as would have been possible with agitation leaching
of crushed roasted ore.
The leach liquor contains approximately 50 g./1. of
VzOs, 20 g./1. of P205, 0.5 g./1. of chromium, 25 g./1.
of chloride ion and 50 g./1. of sodium ion. The vanadium
values were recovered by precipitation with excess ammonium
chloride to produce a crude ammonium metavanadate
product which was purified by dissolving in a
slight excess of sodium carbonate, the solution filtered,
and ammonium metavanadate re-precipitatedin the pure
form by addition of excess ammonium chloride. The pure
ammonium metavanadate was decomposed by heating
to an elevated temperature to produce vanadium pentoxide,
which was fused to black cake. The black cake 35
contained more than 98% V20 5, less than 0.05% phosphorus,
less than 0.02% sulfur, less than 0.5% sodium
and potassium oxide, less than 0.02'% arsenic, less than
0.5% silica and less than 0.5% iron. Thus, it met all
specifications for the commercial product and it was not
necessary to resort to a more involved upgrading.
Example II
The procedure of Example I was followed with the
exception of adding 0.03 pound of calcium oxide for
each pound of ferrophosphorus prior to passing the
roasted ore from the primary roast to the ball mill. Thus,
the added calcium oxide was present in the ferrophosphorus
at the time of the secondary roast.
The leach liquor resulting from leaching the output
from the secondary roaster contained a noticeably
smaller amount of phosphorus and the crude ammonium
metavanadatealso was of much higher purity. It was
possible to purify the crude ammonium metavanadate precipitate
sufficiently by digesting .it in a small amount of
sodium carbonate and complete solution was not necessary
for. purification purposes. After- .a short. digestion
period, excess ammonium chloride was added without
filtration to re-precipitate the vanadium content as ammonium
metavanadate. The ammonium metavanadate
was recovered, decomposed by heating and fused to black
cake as in Example 1.. This procedure produced asatisfactory
vanadium product which met all commercial specifications
without the necessity for further upgrading.
Example III
The procedure of Example I was followed except as
noted below;
In the procedure of Example I, sufficient cooling air
was supplied to the roasters to provide the desired temperature
range during the exothermic portion of the roast.
This resulted in a large volume of gases exiting from the
primary roaster. It w.as difficult to adequately scrub the
large volume of roaster gases, free of the gaseous hydrochloric
.acid.
3,376,103
References Cited
UNITED STATES PATENTS
1/1912 Bleecker 23-16
3/1925 Carpenter 23-19.1
3/1940 Frick et al. 23-19.1
10/1941 Robertson et al. 23-19.1
2/1958 Dunn et al. 23-140 X
9/1965 Burwell et al. 23-18
7/1966 Koerner et al. 23-15
1,015,469
1,531,541
2,193,092
2,257,978
2,822,240
3,206,276
3,259,455
OSCAR R. VERTIZ, Primary Examiner.
H. T. CARTER, Assistant Examiner.
70
10
17. The process of claim 10 wherein the ferrophosphorus
is roasted in the presence of about 0.35-2 parts
by weight of sodium chloride for each part by weight of
ferrophosphorus.
18. The process of claim 10 wherein the roasted ferrophosphorus
from the second roast is cooled by contacting
it with a cooling medium selected from the group consisting
of air, steam and sprayed water, and the cooled
roasted ferrophosphorus is leached with water to produce
a leach liquor containing vanadium values.
19. The process of claim 17 wherein the cooled roasted
ferrophosphorus is percolation leached.
20. A process for recovering vanadium values from
vanadium bearing ferrophosphorus comprising the steps
of roasting under oxidizing conditions in the presence
of an elemental oxygen-'containing gas a mixture consisting
essentially of vanadium bearing ferrophosphorus having
a particle size between about -80 mesh and -400
mesh and sodium chloride having a particle size not
greater than about -8 mesh at a temperature of about
600-750 0 C., the sodium chloride being present in an
amount up to about 0.6 pound for each pound of ferrophosphorus,
the ferrophosphorus being roasted until
when a portion is crushed and leached with water the
resulting leach liquor has a pH value of at least 5.5,
cooling the roasted ore to a temperature not greater
than about 500 0 C. by contacting it with a cooling medium
selected from the group consisting of air, steam
and sprayed water, adding up to about 0.3 pound of the
sodium chloride for each pound of ferrophosphorus to
the roasted ferrophosphorus, reducing the particle size
of the cooled roasted ferrophosphorus to provide particles
having a size not greater than about -3 mesh, thereafter
subjecting a mixture consisting essentially of the
roasted ferrophosphorus and the sodium chloride to a
second roast under oxidizing conditions in the presence
of an elemental oxygen-containing gas at a temperature
of about 600-8000 C., the ferrophosphorus being roasted
in the second roast until when a portion is crushed and
leached with water the resulting leach liquor has a pH
value greater than 7.0, cooling the roasted ferrophosphorus
from the second roast to a temperature not greater
than about 500 0 C. by contacting it with a cooling medium
selected from the group consisting of air, steam and
45 sprayed water, the ferrophosphorus 'containing an added
material during at least one of the roasts providing a
substance selected from the group consisting of (a) up to
about 0.1 pound of magnesium oxide per pound of ferrophosphorus
and (b) up to about 0.1 pound of calcium
oxide per pound of ferrophosphorus, the ferrophosphorus
being cooled during at least a portion of a roast by addition
of water thereto, leaching the roasted ferrophosphorus
with water to produce an aqueous leach liquor
contai?ing solubilized vanadium ~alues, and recovering
vanadIUm values from the leach lIquor.
9
essentially of vanadium bearing ferrophosphorus having
a particle size not greater than about -48 mesh and at
least one substantially neutral salt of an alkali metal selected
from the group consisting of sodium and potassium
and a strong mineral acid at a temperature of about 5
600-750 0 c., adding an additional quantity of the said
alkali metal salt to the roasted ferrophosphorus, reducing
the particle size of the roasted ferrophosphorus, thereafter
subjecting a mixture consisting essentially of the
roasted ferrophosphous and the said alkali metal salt to 10
a second roast under oxidizing conditions in the presence
of an elemental oxygen-containing gas at a temperature
of about 600-800 0 c., the ferrophosphorus being roasted
in the foregoing roasting steps under oxidizing conditions
until vanadium values contained therein are solubilized, 15
leaching the roasted ferrophosphorus with an aqueous
medium to produce an aqueous leach liquor containing
solubilized vanadium values, and recovering vanadium
values from the leach liquor.
9. The process of claim 8 wherein the alkali metal 20
salt is sodium chloride.
10. A process for recovering vanadium values from
vanadium bearing ferrophosphorus comprising the steps
of roasting under oxidizing conditions in the presence of
an elemental oxygen-containing gas a mixture consisting 25
essentially of vanadium bearing ferrophosphorus having
a particle size not greater than about -48 mesh and
sodium chloride having a particle size not greater than
about -8 mesh at a temperature of about 600-750 0 C.,
cooling the roasted ferrophosphorus, adding an additional 30
quantity of the sodium chloride to the roasted ferrophosphorus,
reducing the particle size of the cooled
roasted ferrophosphorus to provide particles having a size
not greater than about -3 mesh, thereafter subjecting a
mixture consisting essentially of the roasted ferrophos- 35
phorus and the sodium chloride to a second roast under
oxidizing conditions in the presence of an elemental
oxygen-containing gas at a temperature of about 600800
0 C., the ferrophosphorus being roasted in the foregoing
roasting steps under oxidizing conditions until vana- 40
dium values contained therein are solubilized, leaching
the roasted ferrophosphorus with an aqueous medium to
produce an aqueous leach liquor containing solubilized
vanadium values, and recovering vanadium values from
the leach liquor.
11. The process of claim 10 wherein the ferrophosphorus
is 'cooled during at least a portion of a roast by
addition of water thereto.
12. The process of claim 10 wherein the ferrophosphorus
is roasted in the first mentioned roast until when 50
a portion is crushed and leached with water the resulting
leach liquor has a pH value of at least 3.3.
13. The process of claim 10 wherein the ferrophosphorus
is roasted in the second mentioned roast until
when a portion is crushed and leached with water the 55
resulting leach liquor has a pH value of at least 6.5.
14. The process of claim 10 wherein a material providing
a substance selected from the group consisting of
(a) up to about 0.1 pound of magnesium oxide per pound
of ferrophosphorus, and (b) up to about 0.1 pound of 60
calcium oxide per pound of ferrophosphorus is added to
the ferrophosphorus prior to at least one of the roasts.
15. The process of claim III wherein the ferrophosphorus
is roasted in the absence of a substantial amount
of added moisture in the gases in contact therewith during 65
at least a portion of a roast.
16. The process of claim 10 wherein the roasted ferrophosphorus
from at least one of the roasts is cooled by
contacting it with a cooling medium selected from the
group consisting of air, steam and sprayed water.
UNITED STATES PATENT OFFICE
CERTIFICATE OF CORRECTION
Patent No. 3,376,103
Angus V. Henrickson et al.
April 2, 1968
It is certified that error appears in the above identified
patent and that said Letters Patent are hereby corrected as
shown below:
C01umn 4, line 41, "2:1 11 should read -- 20:1 --' line 44
"thep re5ent 1l should read -- the present --, Column 8 line 29
IIso 1UbI'l'IZI'de 11 shoul d read -- solubilized __ . ' ,
Signed and sealed this 5th day of August 1969.
(SEAL)
Attest:
Edward M. Fletcher, Jr.
Attesting Officer
WILLIAM E. SCHUYLER, JR.
Commissioner of Patents