Discloses a hydrometallurgical process and system for the recovery of precious metals; specifically palladium, rhodium, and platinum metals, at high purity and with limited waste and environmental fouling.

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.

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.

The present invention relates to an autocatalytic reductive chemical procedure with solid-solid interaction in conditions of supersaturation of salts, via the phenomenon of efflorescence in order to dissolve a copper metal, from a metallogenically primary ore or chalcopyrite concentrate that contains same. The method comprises two steps, referred to as Reductive Activation Step and Dry Autocatalytic Reductive Transformation Step or efflorescence, which can be repeated as many times as necessary to maximise the extraction of copper or base metal of interest. The invention can also be used for sulphurised base metals such as nickel, zinc, cobalt, lead and molybdenum, among others, regardless of the common impurities of sulphurised ores, as occurs with the presence of arsenic.

A process for extracting values from lithium slag comprising: (a) hydrothermally treating lithium slag with an aqueous solution of an alkaline compound at selected temperature and duration; (b) performing an ion exchange step on the alkaline treated lithium slag; and (c) recovering values selected from the group consisting of aluminium compounds, silicon compounds and compounds containing silicon and aluminium.

A method for improved processing of lithium metallurgical solutions comprises the steps of: i. Directing a lithium leach solution containing magnesium to an electrochemical magnesium removal step to form a magnesium depleted lithium leach solution; ii. Directing the magnesium depleted lithium leach solution of step i) to downstream concentration and recovery processes wherein the electrochemical magnesium removal step is a 3-chamber electrochemical configuration to produce magnesium hydroxide precipitate and a separate hydrochloric acid stream, as recoverable by-products.

A method for improved processing of lithium metallurgical solutions comprises the steps of: i. Directing a lithium leach solution containing magnesium to an electrochemical magnesium removal step to form a magnesium depleted lithium leach solution; ii. Directing the magnesium depleted lithium leach solution of step i) to downstream concentration and recovery processes wherein the electrochemical magnesium removal step is a 3-chamber electrochemical configuration to produce magnesium hydroxide precipitate and a separate hydrochloric acid stream, as recoverable by-products.

A method for the precipitation of rare earth sulphate, the method including subjecting a crude rare earth sulphate solution to precipitation in the presence of a water soluble, volatile, organic compound to produce a rare earth sulphate precipitate and an acidic supernatant. The organic compound is preferably selected from the group consisting of methanol, ethanol, iso-propanol, tert-butanol, acetone or mixtures thereof, and is preferably methanol. Preferably, the organic compound is used in the precipitation at a weight ratio of between 0.25:1 to 1.5:1, and preferably 0.5:to 1.25:1, with the crude sulphate solution.

A method for the precipitation of rare earth sulphate, the method including subjecting a crude rare earth sulphate solution to precipitation in the presence of a water soluble, volatile, organic compound to produce a rare earth sulphate precipitate and an acidic supernatant. The organic compound is preferably selected from the group consisting of methanol, ethanol, iso-propanol, tert-butanol, acetone or mixtures thereof, and is preferably methanol. Preferably, the organic compound is used in the precipitation at a weight ratio of between 0.25:1 to 1.5:1, and preferably 0.5:to 1.25:1, with the crude sulphate solution.

Processes are provided in which successive steps of hydrometallurgical value extraction may be carried out using the products of carbon capture and an electrolytic reagent-generating process. The electrolytic process provides an acid leachant and an alkali hydroxide, with the alkali hydroxide then available for use either directly as a precipitant in the hydrometallurgical steps, or available for conversion by carbon capture to an alkali metal carbonate that can in turn be used as the precipitant in the selective hydrometallurgical steps.