Recovery of metal values from process residues

A process for recovering metal values from a source material containing at least niobium and metallic fluorides comprising:

• (a) digesting the source material in sulfuric acid to form a slurry;
• (b) separating the slurry to form at least a first liquid aqueous phase containing niobium and a solid phase;
• (c) contacting the first liquid aqueous phase with a water immiscible organic liquid extractant suitable for extracting niobium to form a first organic liquid phase containing niobium values and a second liquid aqueous phase;
• and
• (d) recovering the niobium values from the first organic aqueous phase.

A process for recovering metal values from a source material containing at least tantalum and metallic fluorides comprising:

• (a) digesting the source material in sulfuric acid to form a slurry;
• (b) separating a first liquid aqueous phase containing tantalum and a solid phase from the slurry;
• (c) contacting the first liquid aqueous phase with a water immiscible organic liquid extractant suitable for extracting tantalum to form a first organic liquid phase containing tantalum values and a second liquid aqueous phase;
• (d) contacting the first organic phase with an aqueous liquid to form a third aqueous phase containing the tantalum values;
• and
• (e) recovering the tantalum values from the third aqueous phase;
• (f) pyrohydrolyzing the separated solid phase by raising the temperature of the solids from about ambient temperature to at least about 700.degree. C. in the presence of water vapor to evolve gaseous sulfuric acid, and gaseous hydrofluoric acid, and a chemically inert residue.

A process for recovering metal and acid values from a source material containing metallic fluorides of at least one metal comprising:

• (a) digesting the source material in sulfuric acid to form a slurry;
• (b) separating a first liquid aqueous phase containing metal values and a solid phase from the slurry;
• (c) removing the metal values from the first liquid aqueous phase by using a separation agent selected from a water immiscible organic liquid extractant suitable for extracting the metal values and an ion exchange resin for selectively removing the metal values;
• (d) recovering the metal values from the separation agent;
• (e) pyrohydrolyzing the separated solid phase by raising the temperature the separated solid phase from about ambient temperature to an elevated temperature of at least about 800.degree. C. to evolve sulfuric acid, hydrofluoric acid, and a chemically inert residue;
• (f) scrubbing the gas with a dilute solution of sulfuric acid to remove sulfuric acid values;
• and
• (g) scrubbing the gas with a dilute solution of hydrofluoric acid to remove hydrofluoric acid values.