Hydrometallurgical process and method for recovering metals

A method, comprising:

• comminuting, by a mill, a feed material comprising a valuable metal-containing mineral;
• forming, by the mill and from the valuable metal-containing mineral, a concentrate containing the valuable metal-containing mineral;
• recovering, by a process plant, the valuable metal from the valuable metal-containing mineral, wherein at least one of the mill and process plant generate a byproduct salt solution from a mineral acid and a base, the byproduct salt solution comprising fluorine and an organic contaminant, wherein the valuable metal is a rare earth, wherein the acid component is hydrochloric acid, wherein the salt in the byproduct salt solution is one or both of sodium chloride and potassium chloride, wherein the base is one or both of sodium hydroxide and potassium hydroxide, and wherein the valuable metal product is a rare earth oxide;
• removing, by an inorganic contaminant purification circuit, at least about 85% of fluorine from the byproduct salt solution;
• removing, by an organic contaminant purification circuit, an organic contaminant from the byproduct salt solution;
• and
• generating, by an electrochemical acid generation plant, the mineral acid and base from the byproduct salt solution to provide the mineral acid and base to at least one of the mill and process plant.

A method, comprising:

• communuting, by a mill, a feed material comprising a valuable metal-containing mineral, wherein the valuable metal is a rare earth;
• forming, by the mill and from the valuable metal-containing mineral, a concentrate containing the rare earth-containing mineral;
• recovering, by a process plant, a valuable metal product from the valuable metal-containing mineral, wherein the valuable metal product is a rare earth oxide;
• generating, by an electrochemical acid generation plant comprising at least one of a chloralkali cell and bipolar membrane electrodialysis cell, the mineral acid and base from the byproduct salt solution and provide the mineral acid to at least one of the mill and process plant, wherein the byproduct salt solution comprises an organic contaminant, wherein the electrochemical acid generation plant removes greater than about 50% of the organic contaminant to form a purified salt solution, and wherein the purified salt solution is introduced into the at least one of a chloralkali cell and bipolar membrane electrodialysis cell to form the acid component and base;
• and
• providing, by a cogen plant, electrical energy and waste heat to at least one of the mill and process plant.

A process, comprising:

• contacting a valuable metal-containing material with a leaching solution to form a pregnant leach solution comprising a dissolved valuable metal;
• recovering the dissolved valuable metal to form a valuable metal product, wherein a byproduct salt solution derived from reaction of an acid and a base is produced by at least one of the contacting and recovering steps, the byproduct salt solution comprising fluorine, wherein the valuable metal is a rare earth, wherein the acid component is hydrochloric acid, wherein the salt in the byproduct salt solution is one or more of sodium chloride and potassium chloride, wherein the base is one or more of sodium hydroxide and potassium hydroxide, and wherein the valuable metal product is a rare earth oxide;
• removing greater than about 50% of the fluorine from the byproduct salt solution to form a purified byproduct salt solution;
• converting, by at least one of a chloralkali cell and bipolar membrane electrodialysis cell, the byproduct salt solution into the acid and the base;
• and
• recycling the acid and/or base to at least one of the contacting and recovering steps.

A method, comprising:

• (a) receiving an aqueous salt solution;
• (b) electrochemically generating an acid and a base from the aqueous salt solution;
• (c) dissolving a plurality of rare earths from a valuable metal-containing feed material to form a rare earth-containing solution, the acid and/or base being used in the dissolving step (c) and the rare earth-containing solution comprising dissolved cerium (III) and multiple other dissolved rare earths;
• (d) selectively oxidizing cerium in the presence of the multiple other dissolved rare earths to form cerium (IV) while maintaining the multiple other dissolved rare earths in a non-oxidized state and thereby precipitate the oxidized rare earth while leaving the at least one other non-oxidized rare earth in solution;
• (e) separating the oxidized rare earth precipitate from the non-oxidized rare earth;
• and
• (f) thereafter separating the multiple other dissolved rare earths in the non-oxidized state from one another by one or more of ion exchange, liquid-liquid extraction, reduction to metal by reaction with a more electropositive metal, electrolytic reduction, fractional distillation, and zone melting.

A process, comprising:

• contacting a valuable metal-containing material with an acidic leaching solution having an acid component to form a pregnant leach solution comprising a dissolved valuable metal;
• recovering the dissolved valuable metal to form a valuable metal product and a byproduct salt solution, the byproduct salt solution is derived from reacting a base with the acid component, wherein the valuable metal is a rare earth, wherein the acid component is hydrochloric acid, wherein the salt in the byproduct salt solution is one or more of sodium chloride and potassium chloride, wherein the base is one or more of sodium hydroxide and potassium hydroxide, and wherein the valuable metal product is a rare earth oxide;
• removing greater than about 50% of a selected contaminant from a byproduct salt solution, wherein the selected contaminant is one or both of:
• (i) an organic contaminant, wherein the organic contaminant is removed from the byproduct salt solution to form a purified salt solution, the selected organic contaminant comprises one or more of a dissolved solvent extraction resin, a dissolved ion exchange resin, a surfactant, a flotation reagent, a coagulant, and a flocculant, and
• (ii) an inorganic contaminant, wherein the inorganic contaminant is removed from the byproduct salt solution to form a purified salt solution, the inorganic contaminant comprises fluorine;
• electrochemically converting the purified salt solution into the acid component and the base;
• recycling the acid component of the electrochemically converting step to the contacting step;
• and
• recycling the base of the electrochemically converting step to at least one of the contacting and recovering steps.