A process disclosed herein is related to the isolation and purification of substantially pure chemicals, including silica gel, sodium silicate, aluminum silicate, iron oxide, and rare earth elements (or rare earth metals, REEs), from massive industrial waste coal ash. In one embodiment, the process includes a plurality of caustic extractions of coal ash at an elevated temperature, followed by an acidic treatment to dissolve aluminum silicate and REEs. The dissolved aluminum silicate is precipitated out by pH adjustment as a solid product while REEs remain in the solution. REEs are captured and enriched using an ion exchange column. Alternatively, the solution containing aluminum silicate and REEs is heated to produce silica gel, which is easily separated from the enriched REEs solution. REEs are then isolated and purified from the enriched solution to afford substantially pure individual REE by a ligand-assisted chromatography. Additionally, a simplified process using one caustic extraction and one acidic extraction with an ion exchange process was also investigated and optimized to afford a comparable efficiency.

The present disclosure broadly relates to a process for recovering magnesium as magnesium oxide and fibrous amorphous silica from serpentinite feedstocks. More specifically, but not exclusively, the present disclosure relates to metallurgical and chemical processes for recovering magnesium oxide and fibrous amorphous silica from serpentinite feedstocks. The process broadly comprises applying a sufficient amount of shear deformation force to the serpentine feedstocks to produce a particulate material of reduced size; subjecting the particulate material to magnetic separation to produce a primary magnetic separation product and iron-reduced tailings; and digesting the iron-reduced tailings into nitric acid, producing a magnesium-rich pregnant solution and insoluble solids. The process further comprises adjusting the pH of the pregnant solution to values ranging from about 5.0 to about 7.0.

Solutions and methods for leaching coinage metals. For example, Solutions and methods for leaching copper and/or silver from a substance comprising copper and/or silver (such as a coinage metal-concentrate, or electronic waste) using a water-miscible stabilizer in combination with leaching reagents to form leach solutions.

The present invention relates to metallurgical processes, and more particularly to a process for producing titaniferous feedstock and fines, a process for agglomerating titaniferous fines, and a process for producing titaniferous metals and titaniferous alloys. Recovery of rare-earth, vanadium and scandium from titanium iron bearing resources is also disclosed. Selective leaching for Scandium recovery from all magnetite type resources such as ilmenite, ferro titanic resources, nickel laterites, magnetite iron resources etc.

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 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.sup.3+ 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.

A method for recovery of precious metals from copper anode slime may include leaching a leach liquor out of the copper anode slime by mixing the copper anode slime with a mixture of nitric acid and sulfuric acid, separating silver from the leach liquor by forming a silver chloride precipitate in the leach liquor by mixing a supersaturated sodium chloride solution with the leach liquor at room temperature and obtaining a first filtrate by filtering the silver chloride precipitate out of the leach liquor. Copper may be separated from the first filtrate by forming a copper hydroxide precipitate in the first filtrate by adjusting pH of the first filtrate at 9 and obtaining a second filtrate by filtering the copper hydroxide precipitate out of the first filtrate. Metallic selenium may be recovered from the second filtrate by reducing the metallic selenium via a chemical reduction utilizing L-ascorbic acid (LAA) as a reducing agent.

Disclosed herein are methods for preparing a hydraulic pre-concentrate enriched in rare earth elements and critical minerals, the method comprising: (a) contacting a raw material with a first base in an amount sufficient to adjust the pH to a value from about 4.0 to about 6.0, thereby forming a mixture comprising a first aqueous phase and a first solid concentrate; (b) separating the first aqueous phase from the first solid concentrate; (c) contacting the first aqueous phase with a second base in an amount sufficient to adjust the pH to a value from about 7.0 to about 9.0, thereby forming a mixture comprising a second aqueous phase and the hydraulic pre-concentrate; (d) removing the second aqueous phase and collecting the hydraulic pre-concentrate; wherein the raw material comprises rare earth elements; and wherein the hydraulic pre-concentrate is enriched in rare earth elements.

In one aspect, the disclosure relates to a continuous process for treating acid mine drainage while simultaneously recovering a high-grade rare earth preconcentrate suitable for extraction of commercially valuable rare earth oxides. In a further aspect, the preconcentrate is from about 0.1% to 5% rare earth elements on a dry weight basis. In another aspect, the disclosure relates to a method for processing the preconcentrate to generate a pregnant leach solution that does not form gels or emulsions and is suitable for processing via solvent extraction. In another aspect, the disclosure relates to a system and plant for carrying out the disclosed process. In still another aspect, the disclosure relates to a composition containing rare earth elements produced by the process disclosed herein. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.

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.