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3,376,103 Process for roasting vanadium ores

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


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