The present application relates to methods for leaching and extraction of precious metals. For example, the present application relates to methods of leaching gold, palladium and/or platinum from a substance comprising gold, palladium and/or platinum (such as a gold-containing ore or a platinum group metal (PGM) concentrate) using an organic solvent that is water-miscible or partially water-miscible.

A process for producing a purified aqueous lithium (sulfate) solution including: processing a lithium-containing raw material to produce a crude aqueous solution containing lithium sulfate; contacting the crude solution with an organic medium, in an extraction step to produce a lithium-loaded organic medium and a raffinate; stripping said lithium-loaded organic medium by means of an aqueous acid stripping solution (e.g., sulfuric acid), to extract the lithium cations from the lithium-loaded medium, to produce: the purified aqueous lithium (sulfate) solution and a stripped organic medium; separating the purified lithium solution from the stripped organic medium; recycling the stripped organic medium to the extraction step, the organic medium including the stripped organic medium; subjecting the raffinate to electrolysis to produce: an alkali (sodium) hydroxide solution contaminated with lithium and a sulfuric acid stream; and recycling the alkali hydroxide and sulfuric acid streams for use within the process.

Provided herein are processes for recovering metal present at low concentration from an acidic aqueous solution, including contacting the acidic aqueous solution with an organic phase solution including one or more 5-(C.sub.8 to C.sub.14 alkyl)-2-hydroxyaryloxime, thereby extracting at least part of the metal from the acidic aqueous phase; increasing or maintaining the concentration of metal in the organic phase solution by recycling a portion of the organic phase solution containing the metal and contacting the organic phase with an acidic aqueous solution containing the metal; contacting the organic phase solution containing metal with an aqueous phase strip solution comprising an inorganic compound that back-extracts the metal, thereby stripping at least part of the metal from the organic phase solution to the aqueous phase strip solution; and separating the metal from the aqueous phase strip solution, thereby recovering the metal.

Provided herein are processes for recovering metal present at low concentration from an acidic aqueous solution, including contacting the acidic aqueous solution with an organic phase solution including one or more 5-(C.sub.8 to C.sub.14 alkyl)-2-hydroxyaryloxime, thereby extracting at least part of the metal from the acidic aqueous phase; increasing or maintaining the concentration of metal in the organic phase solution by recycling a portion of the organic phase solution containing the metal and contacting the organic phase with an acidic aqueous solution containing the metal; contacting the organic phase solution containing metal with an aqueous phase strip solution comprising an inorganic compound that back-extracts the metal, thereby stripping at least part of the metal from the organic phase solution to the aqueous phase strip solution; and separating the metal from the aqueous phase strip solution, thereby recovering the metal.

Apparatuses and methods for extracting desired chemical species and/or impurities from input material. An aspect of the present disclosure comprises a continuous flow system using solvents and other reactants to assist in conversion and extraction of the desired output material and/or removal of specific impurities from the input material through pressure, temperature, and volume control within the extraction system.

Provided are an extraction agent and extraction method that selectively extract and, at a low cost, recover gallium from an acidic solution containing gallium and zinc. The gallium extraction agent comprises an amide derivative represented by general formula (I). In the formula, R.sup.1 and R.sup.2 each indicate the same or different alkyl group, R.sup.3 indicates a hydrogen atom or an alkyl group, and R.sup.4 indicates a hydrogen atom or any given group, other than an amino group, bonded to the α-carbon as an amino acid. The general formula preferably has a glycine unit, a histidine unit, a lysine unit, an aspartic acid unit, or an N-methylglycine unit. By extracting gallium from an acidic solution containing gallium and zinc by means of solvent extraction using the extraction agent, it is possible to selectively extract gallium.

Provided are an extraction agent and extraction method that selectively extract and, at a low cost, recover gallium from an acidic solution containing gallium and zinc. The gallium extraction agent comprises an amide derivative represented by general formula (I). In the formula, R.sup.1 and R.sup.2 each indicate the same or different alkyl group, R.sup.3 indicates a hydrogen atom or an alkyl group, and R.sup.4 indicates a hydrogen atom or any given group, other than an amino group, bonded to the α-carbon as an amino acid. The general formula preferably has a glycine unit, a histidine unit, a lysine unit, an aspartic acid unit, or an N-methylglycine unit. By extracting gallium from an acidic solution containing gallium and zinc by means of solvent extraction using the extraction agent, it is possible to selectively extract gallium.

A method to produce a brine from mixed alum salts, the method comprising the steps of: (i) Dissolving or pulping alum salts (1) containing rubidium alum, cesium alum and/or potassium alum in water or a recycled liquor and adding a neutralising agent to precipitate (20) aluminium as aluminium hydroxide and some sulfate; (ii) Passing the product of step (i) to a solid liquid separation stage (21) to remove precipitated solids (5) from step (i); (iii) A decant or filtrate (6) from step (ii) is passed to a solvent extraction stage (24-27) whereby any contained cesium and rubidium is selectively extracted into the organic phase to form a loaded organic solution (16); (iv) Contacting the loaded organic solution (16) of step (iii) with a scrub solution (17), which is at a pH lower than the extraction pH, to effectively scrub co-loaded potassium from the organic phase; (v) Contacting the scrubbed organic (19) of step (iv) with formic acid (20) to strip cesium and rubidium from the organic, the stripped cesium and rubidium forming a cesium and/or rubidium sulfate brine (21); and (vi) Recycling the stripped organic (22) of step (v) to the extraction stage (24-27).

A method to produce a brine from mixed alum salts, the method comprising the steps of: (i) Dissolving or pulping alum salts (1) containing rubidium alum, cesium alum and/or potassium alum in water or a recycled liquor and adding a neutralising agent to precipitate (20) aluminium as aluminium hydroxide and some sulfate; (ii) Passing the product of step (i) to a solid liquid separation stage (21) to remove precipitated solids (5) from step (i); (iii) A decant or filtrate (6) from step (ii) is passed to a solvent extraction stage (24-27) whereby any contained cesium and rubidium is selectively extracted into the organic phase to form a loaded organic solution (16); (iv) Contacting the loaded organic solution (16) of step (iii) with a scrub solution (17), which is at a pH lower than the extraction pH, to effectively scrub co-loaded potassium from the organic phase; (v) Contacting the scrubbed organic (19) of step (iv) with formic acid (20) to strip cesium and rubidium from the organic, the stripped cesium and rubidium forming a cesium and/or rubidium sulfate brine (21); and (vi) Recycling the stripped organic (22) of step (v) to the extraction stage (24-27).

An object of the present invention is to provide a novel method for extracting ultra high purity alumina from wastewater. Wastewater is recycled, filtered, concentrated and pretreated in order to mix with alkali solution and extraction agent PX-17, undergoing 2 times of purification, adding control agent SX-1 and high temperature heat treatment to finally obtain ultra high purity nano-alumina particles which purity reaches as 99.999% and particle size reaches as 20-200 nm.