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Hydrometallurgy
Hydrometallurgy is a technique within the field of extractive metallurgy, the obtaining of metals from their ores. Hydrometallurgy uses solutions to recover metals from ores, concentrates, and recycled or residual materials. Usually the extracting solution is aqueous (water-based), often containing additives such as acids. In select cases, the extracting solvent is nonaqueous. Brent Hiskey "Metallurgy, Survey" in Kirk-Othmer Encyclopedia of Chemical Technology, 2000, Wiley-VCH, Weinheim. Processing techniques that complement hydrometallurgy are pyrometallurgy, vapour metallurgy, and molten salt electrometallurgy. Hydrometallurgy is typically divided into three general areas: *Leaching *Solution concentration and purification *Metal or metal compound recovery Leaching : Leaching (metallurgy), Leaching involves the use of aqueous solutions to extract metal from metal-bearing materials. The extracting solution is called a lixiviant. The lixiviant is optimized in terms of pH, ox ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid–liquid Extraction
Liquid–liquid extraction, also known as solvent extraction and partitioning, is a method to separate compounds or metal complexes, based on their relative solubility, solubilities in two different Miscibility, immiscible liquids, usually water (polar) and an organic solvent (non-polar). There is a net transfer of one or more Chemical species, species from one liquid into another liquid phase, generally from aqueous to organic. The transfer is driven by chemical potential, i.e. once the transfer is complete, the overall system of chemical components that make up the solutes and the solvents are in a more stable configuration (lower free energy). The solvent that is enriched in solute(s) is called extract. The feed solution that is depleted in solute(s) is called the raffinate. Liquid–liquid extraction is a basic technique in chemical laboratories, where it is performed using a variety of apparatus, from separatory funnels to countercurrent distribution equipment called as Mixe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extractive Metallurgy
Extractive metallurgy is a branch of metallurgical engineering wherein process and methods of extraction of metals from their natural mineral deposits are studied. The field is a materials science, covering all aspects of the types of ore, washing, concentration, separation, chemical processes and extraction of pure metal and their alloying to suit various applications, sometimes for direct use as a finished product, but more often in a form that requires further working to achieve the given properties to suit the applications. The field of ferrous and non-ferrous extractive metallurgy have specialties that are generically grouped into the categories of mineral processing, hydrometallurgy, pyrometallurgy, and electrometallurgy based on the process adopted to extract the metal. Several processes are used for extraction of the same metal depending on occurrence and chemical requirements. Mineral processing Mineral processing begins with beneficiation, consisting of ini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Malachite
Malachite () is a copper Carbonate mineral, carbonate hydroxide mineral, with the chemical formula, formula Basic copper carbonate, Cu2CO3(OH)2. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmite, stalagmitic masses, in fractures and deep, underground spaces, where the water table and hydrothermal fluids provide the means for chemical precipitation. Individual crystals are rare, but occur as slender to Acicular (crystal habit), acicular prisms. Pseudomorphs after more tabular or blocky azurite crystals also occur. Etymology and history The stone's name derives (via , , and Middle English ''melochites'') from Greek language, Greek Μολοχίτης λίθος ''molochites lithos'', "mallow-green stone", from μολόχη ''molochē'', variant of μαλάχη ''malāchē'', "mallow". The mineral was given this name due to its resemblance to the leaves of the Malva, mallow plant. Copper (Cu2+) g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leaching (metallurgy)
Leaching is a process widely used in extractive metallurgy where ore is treated with chemicals to convert the valuable metals within the ore, into soluble salts while the impurity remains insoluble. These can then be washed out and processed to give the pure metal; the materials left over are commonly known as tailings. Compared to pyrometallurgy, leaching is easier to perform, requires less energy and is potentially less harmful as no gaseous pollution occurs. Drawbacks of leaching include its lower efficiency and the often significant quantities of waste effluent and tailings produced, which are usually either highly acidic or alkali as well as toxic (e.g. bauxite tailings). There are four types of leaching: # Cyanide leaching (e.g. gold ore) # Ammonia leaching (e.g. crushed ore) # Alkali leaching (e.g. bauxite ore) # Acid leaching (e.g. sulfide ore) Leaching is also notable in the extraction of rare earth elements, which consists of lanthanides, yttrium and scandium. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rare Earth Element
The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), are a set of 17 nearly indistinguishable lustrous silvery-white soft heavy metals. Compounds containing rare earths have diverse applications in electrical and electronic components, lasers, glass, magnetic materials, and industrial processes. The term "rare-earth" is a misnomer because they are not actually scarce, but historically it took a long time to isolate these elements. They are relatively plentiful in the entire Earth's crust ( cerium being the 25th-most-abundant element at 68 parts per million, more abundant than copper), but in practice they are spread thinly as trace impurities, so to obtain rare earths at usable purity requires processing enormous amounts of raw ore at great expense; thus the name "rare" earths. Scandium and yttrium a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrowinning
Electrowinning, also called electroextraction, is the electrodeposition of metals from their ores that have been put in solution via a process commonly referred to as leaching. Electrorefining uses a similar process to remove impurities from a metal. Both processes use electroplating on a large scale and are important techniques for the economical and straightforward purification of non-ferrous metals. The resulting metals are said to be ''electrowon''. In electrowinning, an electrical current is passed from an inert anode through a ''leach'' solution containing the dissolved metal ions so that the metal is recovered as it is reduced and deposited in an electroplating process onto the cathode. In electrorefining, the anode consists of the impure metal (e.g., copper) to be refined. The impure metallic anode is oxidized and the metal dissolves into solution. The metal ions migrate through the electrolyte towards the cathode where the pure metal is deposited. Insoluble solid impur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lixiviant
A lixiviant is a chemical used in hydrometallurgy to extract elements from its ore. The term lixiviant can be somewhat obscure, as it is not mentioned in reviews of metallurgy. Extraction of gold One of the most famous lixiviants is cyanide, which is used in extracting 90% of mined gold. The combination of cyanide and the oxygen in air converts gold particles into a soluble salt. Once separated from the bulk gangue, the solution is processed in a series of steps to give the metal. A wide variety of less toxic alternatives to cyanide have been evaluated including thioureas, thiocyanate, and thiosulfate. Several of these lixiviants are applicable to metals other than gold. Dissolution of other metals Typically lixiviants are applied to the extraction of ions of valuable metals from some processed form of an ore. Lixiviants are also used for the recovery of metals from wastes and scrap. Circuit boards and spent catalysts often contain platinum and other valuable metals. Some o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Di(2-ethylhexyl)phosphoric Acid
Di(2-ethylhexyl)phosphoric acid (DEHPA or HDEHP) is an organophosphorus compound with the formula (C8H17O)2PO2H. The colorless liquid is a diester of phosphoric acid and 2-ethylhexanol. It is used in the solvent extraction of uranium, vanadium and the rare-earth metals. Preparation DEHPA is prepared through the reaction of phosphorus pentoxide and 2-ethylhexanol: :4 C8H17OH + P4O10 → 2 C8H17O)PO(OH)sub>2O : C8H17O)PO(OH)sub>2O + C8H17OH → (C8H17O)2PO(OH) + (C8H17O)PO(OH)2 These reaction produce a mixture of mono-, di-, and trisubstituted phosphates, from which DEHPA can be isolated based on solubility.Galkin, N.P.; Sudarikov, B.N.; Veryatin, U.D.; Shishkov, Yu.D.; Maiorov, A.A. Technology of Uranium, 1st Ed.; Israel Program for Scientific Translations: Jerusalem, 1966. Use in lanthanide extraction DEHPA can be used to extract lanthanides (rare earths) from aqueous solutions, it is commonly used in the lanthanide sector as an extraction agent. In general the dist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cementation (metallurgy)
Cementation is a method for obtaining metals from solutions of the metal ion. It is a type of precipitation, in which ions are reduced to zero valence at a solid metallic interface. A cementation step often follows leaching. Cementation of copper is a common example. Copper ions in solution, often from an ore leaching process, convert to metallic copper in the presence of solid iron. The iron oxidizes, and the copper ions are reduced through the electron transfers. The reaction is spontaneous because copper is higher on the galvanic series than iron. : Cu2+(aq) + Fe(s) → Cu(s) + Fe2+(aq) Cementation was a historically useful process for the production of copper, where the precipitated solid copper metal was recovered as flakes or powder on the surface of scrap iron. Cementation is used industrially to recover a variety of heavy metals including cadmium, and the cementation of gold by zinc in the Merrill–Crowe process accounts for a substantial fraction of world gold p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vat Leaching
In metallurgical processes tank leaching is a hydrometallurgical method of extracting valuable material (usually metals) from ore. Tank vs. vat leaching Factors Tank leaching is usually differentiated from vat leaching on the following factors: # In tank leaching the material is ground sufficiently fine to form a slurry or pulp, which can flow under gravity or when pumped. In vat leaching typically a coarser material is placed in the vat for leaching, this reduces the cost of size reduction; # Tanks are typically equipped with agitators, baffles, gas introduction equipment designed to maintain the solids in suspension in the slurry, and achieve leaching. Vats usually do not contain much internal equipment, except for agitators. # Tank leaching is typically continuous Continuity or continuous may refer to: Mathematics * Continuity (mathematics), the opposing concept to discreteness; common examples include ** Continuous probability distribution or random variable in probabil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solvent Extraction
A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for Chemical polarity#Polarity of molecules, polar molecules, and the most common solvent used by living things; all the ions and proteins in a Cell (biology), cell are dissolved in water within the cell. Major uses of solvents are in paints, paint removers, inks, and dry cleaning. Specific uses for Organic compound, organic solvents are in dry cleaning (e.g. tetrachloroethylene); as paint thinners (toluene, turpentine); as nail polish removers and solvents of glue (acetone, methyl acetate, ethyl acetate); in spot removers (hexane, petrol ether); in detergents (D-limonene, citrus terpenes); and in perfumes (ethanol). Solvents find various applications in chemical, pharmaceutical, oil, and gas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ion Exchange
Ion exchange is a reversible interchange of one species of ion present in an insoluble solid with another of like charge present in a solution surrounding the solid. Ion exchange is used in softening or demineralizing of water, purification of chemicals, and separation of substances. Ion exchange usually describes a process of purification of aqueous solutions using solid polymeric ion-exchange resin. More precisely, the term encompasses a large variety of processes where ions are exchanged between two electrolytes. Aside from its use to purify drinking water, the technique is widely applied for purification and separation of a variety of industrially and medicinally important chemicals. Although the term usually refers to applications of synthetic (human-made) resins, it can include many other materials such as soil. Typical ion exchangers are ion-exchange resins (functionalized porous or gel polymer), zeolites, montmorillonite, clay, and soil humus. Ion exchangers are ei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
