Granted Patent B1

US 6,843,970 · App. 08/623,852 · Granted Jan 18, 2005

Abstract

Claims (64)

1. A process for recovering metal values including tantalum metal values and niobium metal values from a source material comprising tantalum, niobium and uranium metal values, the process comprising:

digesting the source material in a sulfuric acid solution comprising:

sulfuric acid;

a reducing agent; and

an additive comprising carbon;

for a period of time sufficient to solubilize tantalum metal values and niobium metal values and form a digestion mixture comprising an aqueous phase comprising solubilized tantalum metal values and niobium metal values, and a solid phase comprising uranium metal values;

heating the digestion mixture for a period of time sufficient to attain a temperature of 75-95° C.; and

separating the resulting solution comprising tantalum metal values and niobium metal values from the remaining solids comprising uranium metal values.

2. The process of claim 1 wherein the sulfuric acid solution further comprises hydrofluoric acid.

3. The process of claim 1 wherein the reducing agent comprises iron, aluminum or mixtures thereof.

4. The process of claim 3 wherein the additive comprises activated carbon.

5. A process for separating and recovering metal values from a digestion mixture of metal containing material, including metal values to be recovered, tantalum and/or niobium metal values and one or more additional metal values, comprising:

digesting the metal containing material in a sulfuric acid solution comprising:

sulfuric acid;

a reducing agent; and

a carbon source which differs from the reducing agent;

for a period of time sufficient to solubilize the metal values to be recovered

heating the digestion mixture for a period of time sufficient to attain a temperature of 75-95° C.; and

separating the resulting solution from the remaining solids;

wherein the sulfuric acid solution further comprises hydrofluoric acid as a source of fluoride ion.

6. A process for separating and recovering metal values from a digestion mixture of metal containing material, including metal values to be recovered, tantalum and/or niobium metal values and one or more additional metal values, comprising:

digesting the metal containing material in a sulfuric acid solution comprising:

sulfuric acid;

a reducing agent; and

a carbon source which differs from the reducing agent;

for a period of time sufficient to solubilize the metal values to be recovered;

heating the digestion mixture for a period of time sufficient to attain a temperature of 75-95° C.; and

separating the resulting solution from the remaining solids;

wherein the sulfuric acid solution comprises:

0.09 to 0.4 pounds of concentrated sulfuric acid per pound of metal containing material solids (dry basis);

0.01 to 0.03 pounds of a reducing agent per pound of metal containing material solids (dry basis);

0.01 to 0.03 pounds of a carbon source per pound of metal containing material solids (dry basis); and

sufficient water to make a solution of 5 to 15% sulfuric acid in water.

7. The process of claim 6 wherein the sulfuric acid solution further comprises: 0.05 to 0.2, pounds of at least 50% hydrofluoric acid (HF) as a source of fluoride ion.

8. The process of claim 6 wherein the sulfuric acid solution comprises:

0.33 pounds of concentrated sulfuric acid per pound of solids (dry basis);

0.02 pounds of a reducing agent per pound of solids (dry basis);

0.02 pounds of a carbon source per pound of solids (dry basis) and

sufficient water to make a solution of 11% in sulfuric acid.

9. The process of claim 8 wherein the sulfuric acid solution further comprises: 0.12 pounds per pound of solids (dry basis) and 70% hydrofluoric acid (HF) as a source of fluoride ion.

10. The process of claim 6 further comprising the step of cooling the heated digestion mixture and wherein:

the metal containing material is digested for at least 1 hour in the sulfuric acid solution;

the digestion mixture is heated to above 75° C., for at least 0.5 hour;

the resulting mixture is cooled to below 60° C.;

and the resulting solution is separated by filtering.

11. The process of claim 7 further comprising the step of cooling the heated digestion mixture and wherein:

the metal containing material is digested for at least 1 hour in the sulfuric acid solution;

the digestion mixture is heated to above 75° C., for at least 0.5 hour;

the resulting mixture is cooled to below 60° C.;

and the resulting solution is separated by filtering.

12. The process of claim 6 wherein the reducing agent is iron.

13. The process of claim 7 wherein the reducing agent is iron.

14. The process of claim 6 wherein the carbon source is activated carbon.

15. The process of claim 7 wherein the carbon source is activated carbon.

16. A process for separating and recovering metal values from a digestion mixture of metal containing material, including metal values to be recovered, tantalum and/or niobium metal values and one or more additional metal values, comprising:

digesting the metal containing material in a sulfuric acid solution comprising:

sulfuric acid;

a reducing agent; and

a carbon source which differs from the reducing agent;

for a period of time sufficient to solubilize the metal values to be recovered;

heating the digestion mixture for a period of time sufficient to attain a temperature of 75-95° C.; and

separating the resulting solution from the remaining solids; further comprising the following steps after the separation step:

washing the separated undissolved solids with a volume of water equal to the volume of the resulting solution separated and

recycling the wash water into the sulfuric acid solution utilized in the digestion step.

Assignments (8)