Electrowinning, also called electroextraction, is the electrodeposition of metals from their ores that have been put in solution or liquefied. The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across An ore is a volume of rock containing components or Minerals in a mode of occurrence that renders it valuable for mining 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. Electroplating is the process of using electrical current to reduce Cations of a desired material from a solution and coat a conductive object Ferrous, in the chemical science realm indicates a bivalent iron compound (+2 oxidation state (as opposed to Ferric, which indicates a trivalent iron compound (+3 oxidation The resulting metals are said to be electrowon.
In electrowinning, a current is passed from an inert anode through a liquid leach solution containing the metal so that the metal is extracted as it is deposited in an electroplating process onto the cathode. In electrorefining, the anodes consist of unrefined impure metal, and as the current passes through the acidic electrolyte the anodes are corroded into the solution so that the electroplating process deposits refined pure metal onto the cathodes. [1]
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History
Electrowinning is the oldest industrial electrolytic process. An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium It was first demonstrated experimentally by von Leuchtenberg in 1747. Year 1747 ( MDCCXLVII) was a Common year starting on Sunday (link will display the full calendar of the Gregorian calendar (or a Later the English chemist Humphrey Davy obtained sodium metal in elemental form for the first time in 1807 by the electrolysis of molten sodium hydroxide. Sir Humphry Davy 1st Baronet FRS MRIA (17 December 1778 &ndash 29 May 1829 was a British Chemist and inventor Sodium (ˈsoʊdiəm is an element which has the symbol Na( Latin natrium, from Arabic natrun) atomic number 11 atomic mass 22 A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. Year 1807 ( MDCCCVII) was a Common year starting on Thursday (link will display the full calendar of the Gregorian calendar (or a Common In chemistry and manufacturing electrolysis is a method of separating chemically bonded elements and compounds by passing an Electric current Sodium hydroxide ( Na[[hydroxide OH]]) also known as Lye, caustic soda and (incorrectly according to IUPAC nomenclature James Elkington patented the commercial process in 1865 and opened the first successful plant in Pembrey, Wales in 1869. Year 1865 ( MDCCCLXV) was a Common year starting on Sunday (link will display the full calendar of the Gregorian calendar (or a Common year Year 1869 ( MDCCCLXIX) is a Common year starting on Friday (link will display the full calendar of the Gregorian calendar (or a Common year The first commercial plant in the United States was the Balbach and Sons Refining and Smelting Company in Newark, New Jersey in 1883. Balbach Smelting & Refining Company (also known as Balbach and Sons Refining and Smelting Company) was a smelting plant in Year 1883 ( MDCCCLXXXIII) was a Common year starting on Monday (link will display the full calendar of the Gregorian calendar (or a Common
Applications
The most common electrowon metals are lead, copper, gold, silver, zinc, aluminium, chromium, cobalt, manganese, and the rare-earth and alkali metals. Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Gold (ˈɡoʊld is a Chemical element with the symbol Au (from its Latin name aurum) and Atomic number 79 Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen Zinc (ˈzɪŋk from Zink is a Metallic Chemical element with the symbol Zn and Atomic number 30 WikipediaNaming Chromium (ˈkroʊmiəm is a Chemical element which has the symbol Cr and Atomic number 24 Cobalt (ˈkoʊbɒlt is a hard lustrous silver-grey Metal, a Chemical element with symbol Co. Manganese (ˈmæŋgəniːz is a Chemical element, designated by the symbol Mn. Rare earth elements and rare earth metals are according to IUPAC, the collection of seventeen Chemical elements in the Periodic table, namely Trends The alkali metals show a number of trends when moving down the group - for instance decreasing electronegativity increasing reactivity and decreasing melting and boiling For aluminium, this is the only production process employed. Several industrially important active metals (which react strongly with water) are produced commercially by electrolysis of their pyrochemical molten salts. Experiments using electrorefining to process spent nuclear fuel have been carried out. Electrorefining may be able to separate heavy metals such as plutonium, caesium, and strontium from the less-toxic bulk of uranium. Caesium or cesium (ˈsiːziəm is the Chemical element with the symbol Cs and Atomic number 55 Strontium (ˈstrɒntiəm /ˈstrɒnʃiəm/) is a Chemical element with the symbol Sr and the Atomic number 38 Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the Many electroextraction systems are also available to remove toxic (and sometimes valuable) metals from industrial waste streams.
Process
Most metals occur in nature in their oxidized form (ores) and thus must be reduced to their metallic forms. An ore is a volume of rock containing components or Minerals in a mode of occurrence that renders it valuable for mining The ore is dissolved following some preprocessing in an aqueous electrolyte or in a molten salt and the resulting solution is electrolyzed. An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium Salt is a Dietary mineral composed primarily of Sodium chloride that is essential for Animal life but toxic to most land plants The metal is deposited on the cathode (either in solid or in liquid form), while the anodic reaction is usually oxygen evolution. A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device An anode is an Electrode through which Electric current flows into a polarized electrical device Oxygen evolution is the process of generating molecular Oxygen through Chemical reaction. Several metals are naturally present as metal sulfides; these include copper, lead, molybdenum, cadmium, nickel, silver, cobalt and zinc. The term sulfide ( sulphide in British English) refers to several types of Chemical compounds containing Sulfur in its lowest Oxidation Molybdenum (məˈlɪbdənəm from the Greek word for the metal " Lead " is a Group 6 Chemical element with the symbol Mo Cadmium (ˈkædmiəm is a Chemical element with the symbol Cd and Atomic number 48 Nickel (ˈnɪkəl is a metallic Chemical element with the symbol Ni and Atomic number 28 Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen In addition, gold and platinum group metals are associated with sulfidic base metal ores. Gold (ˈɡoʊld is a Chemical element with the symbol Au (from its Latin name aurum) and Atomic number 79 Platinum (ˈplætɪnəm is a Chemical element with the Atomic symbol Pt and an Atomic number of 78 Most metal sulfides or their salts, are electrically conductive and this allows electrochemical redox reactions to efficiently occur in the molten state or in aqueous solutions. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state
Some metals, including arsenic and nickel do not electrolyze out but remain in the electrolyte solution. Arsenic (ˈɑrsənɪk is a Chemical element that has the symbol As and Atomic number of 33 These are then reduced by chemical reactions to refine the metal. Other metals, which during the processing of the target metal have been reduced but not deposited at the cathode, sink to the bottom of the electrolytic cell, where they form a substance referred to as anode sludge or anode slime. The metals in this sludge can be removed by standard pyrorefining methods.
Because metal deposition rates are related to available surface area, maintaining properly working cathodes is important. Two cathode types exist, flat-plate and reticulated cathodes, each with its own advantages. Flat-plate cathodes can be cleaned and reused, and plated metals recovered. Reticulated cathodes have a much higher deposition rate compared to flat-plate cathodes. However, they are not reusable and must be sent off for recycling. Alternatively, starter cathodes of pre-refined metal can be used, which become an integral part of the finished metal ready for rolling or further processing. [1]
References
External links
- Recent Development and Trends in Electrorefining
- High Throughput Electrorefining of Uranium in Pyro-reprocessing
- Aluminum Electrowinning and Electrorefining
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