Method for recovering vanadium-values from vanadium-bearing iron ores and iron ore concentrates

Abstract

Method for extracting vanadium-values from vanadium-bearing iron ores and/or iron ore concentrates including mixing the iron ores and/or iron ore concentrates with a calcium containing material, roasting the mix in an oxidizing atmosphere at a temperature for a time to produce calcium vanadates, comminuting the roasted mix and leaching the comminuted roasted mix in an aqueous solution containing carbonate or bicarbonate compounds to produce vanadates which are readily soluble in the aqueous leaching solution and simultaneously producing substantially insoluble calcium carbonate or calcium bicarbonate which remains as part of the undissolved residue containing iron-values. The vanadate-rich aqueous leaching solution is separated from the undissolved residue containing iron-values and treated by known methods to recover the vanadium-values. The undissolved residue can be processed to recover the iron-values.

We claim: 
     
       1. An improved method for extracting vanadium-values from vanadium-bearing iron ores wherein said ores are comminuted to a relatively fine particle size and are roasted and leached to produce a vanadate-rich aqueous solution and an undissolved residue containing iron-values, without contaminating said undissolved residues with alkali, said method comprising: a. mixing said comminuted vanadium-bearing iron ores and at least one calcium containing material taken from the group consisting of limestone, lime, hydrated lime and dolomite,   b. charging the mix into a furnace,   c. roasting the mix at a temperature for a time in an atmosphere containing oxygen to oxidize the vanadium-values therein and to form calcium vanadates,   d. discharging the roasted mix from the furnace,   e. cooling the roasted mix,   f. comminuting the roasted mix,   g. leaching the comminuted roasted mix in an aqueous solution of at least one material taken from the group consisting of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonium carbonate, ammonium bicarbonate and water sparged with CO 2  gas for a time to react a substantial portion of the calcium vanadates with the leaching agent to form vanadates which are readily soluble in the aqueous solution to form a vanadate-rich aqueous solution and at least one calcium compound taken from the group consisting of calcium carbonate and calcium bicarbonate which is substantially insoluble in the aqueous solution and which remains in the undissolved residue containing iron-values, and   h. separating the vanadate-rich aqueous solution from the undissolved residue containing iron-values.   
     
     
       2. The improved method of claim 1 wherein the calcium containing material in step (a) is limestone. 
     
     
       3. The improved method of claim 1 wherein the calcium containing material in step (a) is a chemical-grade limestone. 
     
     
       4. The improved method of claim 2 wherein the limestone is added in a ratio of about 100 pounds to about 200 pounds per ton of the iron ores. 
     
     
       5. The improved method of claim 1 wherein the aqueous leaching solution of step (g) contains an amount of sodium carbonate sufficient to extract a major portion of the calcium vanadates formed during roasting. 
     
     
       6. The improved method of claim 5 wherein the aqueous leaching solution contains about 0.25 to about 15% sodium carbonate. 
     
     
       7. The improved method of claim 1 wherein the aqueous leaching solution of step (g) contains an amount of at least one compound taken from the group consisting of ammonium carbonate and ammonium bicarbonate sufficient to extract a major portion of the calcium vanadates formed during roasting. 
     
     
       8. The improved method of claim 7 wherein the aqueous leaching solution contains about 0.25 to about 15% ammonium carbonate. 
     
     
       9. The improved method of claim 1 wherein the mix of step (a) is balled prior to roasting. 
     
     
       10. An improved method for extracting vanadium-values from vanadium-bearing iron ore concentrates wherein said iron ore concentrates are roasted and leached to produce a vanadate-rich aqueous solution and an undissolved residue containing iron-values without contaminating said undissolved residues with alkali, said method comprising: a. mixing comminuted particles of said iron ore concentrates with at least one calcium containing material taken from the group consisting of limestone, lime, hydrated lime, and dolomite,   b. charging the mix into a furnace,   c. roasting the mix at a temperature for a time in an atmosphere containing oxygen to oxidize the vanadium-values therein and to form calcium vanadates,   d. discharging the roasted mix from the furnace,   e. cooling the roasted mix,   f. comminuting the roasted mix,   g. leaching the comminuted roasted mix in an aqueous solution of at least one material taken from the group consisting of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonium carbonate, ammonium bicarbonate, and water sparged with carbon dioxide gas for a time sufficient to react a substantial portion of the calcium vanadates with the leaching agent to form vanadates which are readily soluble in the aqueous solution to form a vanadate-rich aqueous solution and at least one calcium compound taken from the group consisting of calcium carbonate and calcium bicarbonate which is substantially insoluble in the aqueous solution and which remains in the undissolved residue containing iron-values, and   h. separating the undissolved residue containing iron-values from the vanadate-rich aqueous solution.   
     
     
       11. The improved method of claim 10 wherein the calcium containing material in step (a) is limestone. 
     
     
       12. The improved method of claim 10 wherein the calcium containing material in step (a) is chemical-grade limestone. 
     
     
       13. The improved method of claim 11 wherein the limestone is added in step (a) in a ratio of about 100 pounds to about 200 pounds per ton of the iron ores and iron ore concentrates. 
     
     
       14. The improved method of claim 10 wherein the aqueous leaching solution of step (g) contains sodium carbonate. 
     
     
       15. The improved method of claim 10 wherein the aqueous leaching solution of step (g) is ammonium carbonate. 
     
     
       16. The improved method of claim 14 wherein the aqueous leaching solution contains about 0.25 to about 15% sodium carbonate. 
     
     
       17. The improved method of claim 15 wherein the aqueous leaching solution contains about 0.25 to about 15% ammonium carbonate. 
     
     
       18. The improved method of claim 10 wherein the mix of step (a) is roasted at a temperature within the range of about 2300° to about 2500° F. 
     
     
       19. The improved method of claim 10 wherein the mix of step (a) is roasted within a temperature range of about 2350° to about 2450° F. 
     
     
       20. The improved method of claim 10 wherein the mix of step (a) is formed into green balls prior to roasting. 
     
     
       21. An improved method for extracting vanadium-values from vanadium-bearing iron ores wherein said ores are comminuted to a relatively fine particle size and are roasted and leached to produce a vanadate-rich aqueous solution and an undissolved residue containing iron-values, and wherein said vanadates which are recovered from said vanadate-rich aqueous solution and said undissolved residue containing iron-values are alkali-free, said method comprising: a. forming a mix of said comminuted vanadium-bearing iron ores and at least one calcium containing material taken from the group consisting of limestone, lime, hydrated lime and dolomite,   b. charging said mix into a furnace,   c. roasting said mix at a temperature for a time in an atmosphere containing oxygen to oxidize the vanadium-values in said vanadium-bearing iron ores and to form calcium vanadates therefrom,   d. discharging the roasted mix from the furnace,   e. cooling the roasted mix,   f. comminuting the cooled roasted mix,   g. leaching the comminuted cooled mix in an aqueous solution containing at least one compound taken from the group consisting of ammonium carbonate and ammonium bicarbonate for a time to react a substantial portion of said calcium vanadates with said ammonium carbonate and said ammonium bicarbonate to form ammonium vanadates which are readily soluble in said aqueous leaching solution to form a vanadate-rich aqueous solution and at least one calcium compound taken from the group consisting of calcium carbonate and calcium bicarbonate which is substantially insoluble in said aqueous leaching solution and which remains in said undissolved residue containing iron-values, and   h. separating said vanadate-rich aqueous leaching solution from said undissolved residue containing iron-values.   
     
     
       22. The improved method of claim 21 wherein the calcium containing material in step (a) is limestone. 
     
     
       23. The improved method of claim 21 wherein the calcium containing material in step (a) is chemical-grade limestone. 
     
     
       24. The improved method of claim 22 wherein the limestone is added in a ratio of about 100 pounds to about 200 pounds per ton of the iron ores. 
     
     
       25. The improved method of claim 21 wherein the aqueos solution of step (g) is ammonium carbonate. 
     
     
       26. The improved method of claim 25 wherein the aqueous solution contains about 0.25 to about 15% ammonium carbonate. 
     
     
       27. The improved method of claim 21 wherein the mix of step (a) is formed into green balls prior to roasting. 
     
     
       28. An improved method for extracting vanadium-values from vanadium-bearing iron ores and iron ore concentrates and admixtures thereof, wherein said iron ores and iron ore concentrates have a relatively fine particle size and are roasted and leached to produce an aqueous solution containing readily soluble vanadates and a substantially insoluble residue containing iron-values low in alkali, said method comprising: a. mixing said relatively fine particles of said iron ores and iron ore concentrates and limestone in a weight ratio of about one ton of said iron ores and iron ore concentrates to about 100 pounds to about 200 pounds of limestone,   b. balling the mix,   c. charging the balled mix into a furnace,   d. roasting the balled mix within a temperature range of about 2300° to about 2500° F. for a time in an atmosphere containing oxygen to oxidize the vanadium-values therein and to form calcium vanadates,   e. discharging the roasted balled mix from the furnace,   f. cooling the roasted balled mix,   g. comminuting the cooled ball mix,   h. leaching the comminuted particles of the mix in an aqueous solution containing about 0.25 to about 15% of at least one compound taken from the group consisting of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium carbonate, and ammonium bicarbonate, for a time to react a substantial portion of said calcium vanadates with the carbonate or bicarbonate compound in the leaching solution to form vanadates which are readily soluble in the aqueous leaching solution to form a vanadate-rich aqueous solution and at least one compound taken from the group consisting of calcium carbonate and calcium bicarbonate which is substantially insoluble in the aqueous solution and which remains as part of the undissolved residue containing iron-values, and   i. separating the vandate-rich solution from the undissolved residue containing iron-values.   
     
     
       29. The improved method of claim 28 wherein the calcium containing compound in step (a) is limestone. 
     
     
       30. The improved method of claim 28 wherein the limestone in step (a) is chemical-grade limestone. 
     
     
       31. The improved method of claim 28 wherein the aqueous solution in step (h) contains sodium carbonate. 
     
     
       32. The improved method of claim 28 wherein the aqueous solution in step (h) contains ammonium carbonate.