A method for cleanly extracting metallic silver includes: mixing an acidic solution containing Ce.sup.4+ and NO.sub.3.sup.− with a silver-containing material for leaching; after the leaching is completed, carrying out a solid-liquid separation to obtain a leaching solution containing Ce.sup.3+ and Ag.sup.+; and electrolyzing the leaching solution, wherein an oxidation reaction of Ce′ occurs at an anode to realize a regeneration of Ce.sup.4+ and an electrolytic reduction occurs at a cathode to reduce Ag.sup.+ to obtain the metallic silver. Ce.sup.4+ is used as a leaching agent and an intermediate oxidant to implement a cyclic operation of solution leaching and electrolytic regeneration on the silver-containing material. Almost no NO.sub.x and waste liquid are caused by the extraction process, and the invention is clean and environmentally friendly.

Methods of recovering rare earth elements, vanadium, cobalt, or lithium from coal are described. The coal is dissolved in a first solvent to dissolve organic material in the coal and create a slurry containing coal ash enriched with rare earth elements, vanadium, cobalt, or lithium. The enriched coal ash is separated from the first solvent. Residual organic material is removed from the coal ash. The rare earth elements, vanadium, cobalt, or lithium can then be recovered from the coal ash. The coal ash is mixed with an acid stream that dissolves the rare earth elements, thereby creating (i) a leachate containing the rare earth elements and (ii) leached ash. The leachate is heated to obtain acid vapor and an acid-soluble rare earth concentrate. The acid-soluble rare earth concentrate can be fed to a hydrometallurgical process to separate and purify the rare earth elements.

A process for the selective recovery of lithium values from feedstock is provided. The process includes concentration by one or more of air classification and flotation; selective leaching to remove Mg, Ca or Na formations; and leaching/sonication with an acid. Further, a method of beneficiating a lithium-containing ore is provided treating an aqueous pulp of the lithium-containing ore with a conditioning reagent; and floating, lithium values fraction of the lithium-containing ore from gangue slimes, wherein the treating improves the selectivity of an anionic collector to one or more of spodumene and said lithium values. Further, a process for the selective recovery of lithium from lithium ion batteries is provided.

A method for extracting rare earth elements (REEs) from a REE hyperaccumulator, including: subjecting the REE hyperaccumulator to microwave-assisted digestion to obtain a REE extract; subjecting the REE extract to absorption with a chelating resin and elution to obtain a purified REE solution; and subjecting the purified REE solution to precipitation and calcination to obtain high-purity rare earth compound.

The recovery of noble metal(s) from noble-metal-containing material is generally described. The noble metal(s) can be recovered selectively, in some cases, such that noble metal(s) is at least partially separated from non-noble-metal material within the material. Noble metal(s) may be recovered from noble-metal-containing material using mixtures of acids, in some instances. In some cases, the mixture can comprise nitric acid and/or another source of nitrate ions and at least one supplemental acid, such as sulfuric acid, phosphoric acid, and/or a sulfonic acid. The amount of nitrate ions within the mixture can be, in some instances, relatively small compared to the amount of supplemental acid within the mixture. In some cases, the recovery of noble metal(s) using the acid mixtures described herein can be enhanced by transporting an electric current between an electrode and the noble metal(s) of the noble-metal-containing material. In some cases, acid mixtures can be used to recover silver from particular types of scrap materials, such as scrap material comprising silver metal and cadmium oxide and/or scrap material comprising silver metal and tungsten metal.

The recovery of noble metal(s) from noble-metal-containing material is generally described. The noble metal(s) can be recovered selectively, in some cases, such that noble metal(s) is at least partially separated from non-noble-metal material within the material. Noble metal(s) may be recovered from noble-metal-containing material using mixtures of acids, in some instances. In some cases, the mixture can comprise nitric acid and/or another source of nitrate ions and at least one supplemental acid, such as sulfuric acid, phosphoric acid, and/or a sulfonic acid. The amount of nitrate ions within the mixture can be, in some instances, relatively small compared to the amount of supplemental acid within the mixture. In some cases, the recovery of noble metal(s) using the acid mixtures described herein can be enhanced by transporting an electric current between an electrode and the noble metal(s) of the noble-metal-containing material. In some cases, acid mixtures can be used to recover silver from particular types of scrap materials, such as scrap material comprising silver metal and cadmium oxide and/or scrap material comprising silver metal and tungsten metal.

A method for extracting a rare earth metal from a mixture of one or more rare earth metals, said method comprising contacting an acidic solution of the rare earth metal with a composition which comprises an ionic liquid to form an aqueous phase and a non-aqueous phase into which the rare earth metal has been selectively extracted; recovering the rare earth metal from the non-aqueous phase; and processing the recovered rare earth metal into a rare earth metal oxide.

The recovery of noble metal(s) from noble-metal-containing material is generally described. The noble metal(s) can be recovered selectively, in some cases, such that noble metal(s) is at least partially separated from non-noble-metal material within the material. Noble metal(s) may be recovered from noble-metal-containing material using mixtures of acids, in some instances. In some cases, the mixture can comprise nitric acid and/or another source of nitrate ions and at least one supplemental acid, such as sulfuric acid, phosphoric acid, and/or a sulfonic acid. The amount of nitrate ions within the mixture can be, in some instances, relatively small compared to the amount of supplemental acid within the mixture. In some cases, the recovery of noble metal(s) using the acid mixtures described herein can be enhanced by transporting an electric current between an electrode and the noble metal(s) of the noble-metal-containing material. In some cases, acid mixtures can be used to recover silver from particular types of scrap materials, such as scrap material comprising silver metal and cadmium oxide and/or scrap material comprising silver metal and tungsten metal.

Provided is a method for obtaining high-purity scandium oxide efficiently from a solution containing scandium. The method for producing high-purity scandium oxide of the present invention has a first firing step S12 for subjecting a solution containing scandium to oxalation treatment using oxalic acid and firing the obtained crystals of scandium oxalate at a temperature of 400 to 600° C., inclusive, a dissolution step S13 for dissolving the scandium compound obtained by firing in one or more solutions selected from hydrochloric acid and nitric acid to obtain a solution, a reprecipitation step S14 for subjecting the solution to oxalation treatment using oxalic acid and generating a reprecipitate of scandium oxalate, and a second firing step S15 for firing the reprecipitate of obtained scandium oxalate to obtain scandium oxide.

A process of isolating samarium from a hydrophilic composition comprises nitrate ions, europium and samarium, by reducing europium(III) to europium(II) in this hydrophilic composition, and by extracting the samarium with a water-immiscible organic phase comprising an ionic liquid comprising nitrate anions.