Electrometallurgy

Last updated
Anodized titanium (detail) - a.jpg Anodized titanium (detail) - a.jpg
Anodized titanium (detail) - a.jpg

Electrometallurgy is a method in metallurgy that uses electrical energy to produce metals by electrolysis. It is usually the last stage in metal production and is therefore preceded by pyrometallurgical or hydrometallurgical operations. [1] The electrolysis can be done on a molten metal oxide (smelt electrolysis) which is used for example to produce aluminium from aluminium oxide via the Hall-Hérault process. Electrolysis can be used as a final refining stage in pyrometallurgical metal production (electrorefining) and it is also used for reduction of a metal from an aqueous metal salt solution produced by hydrometallurgy (electrowinning).

Contents

Processes

Electrometallurgy is the field concerned with the processes of metal electrodeposition. There are four categories of these processes:

Molten Oxide Electrolysis

MOE scheme Molten Oxide Electrolysis.png
MOE scheme

Molten Oxide Electrolysis in steelmaking is utilizing electrons as the reducing agent instead of coke as in conventional blast furnace. For steel production, this method uses an inert anode (Carbon, Platinum, Iridium or Chromium-based alloy) [4] and places iron ore in the cathode. The electrochemical reaction in this Molten Oxide cell can reach up to 1600 °C, a temperature that melts iron ore and electrolyte oxide. [5] Then the molten iron ore decompose following this reaction.

[6]

The electrolysis reaction will produce molten pure iron as a main product and oxygen as its by-product. Because this process does not add coke in the process, no CO2 gas is produced. So no direct greenhouse gas emission. Moreover, if the electricity to run such cells comes from renewable sources, this process may have zero emissions. This technology also can be implemented for producing Nickel, Chromium, and Ferrochromium.

Currently Massachusetts-based Boston Metal company is in a process to scale up this technology to an industrial level. [6]

Direct Decarburization Electrorefining

Direct Decarburization Reaction Direct Decarburization.webp
Direct Decarburization Reaction

The purpose of this method is to reduce carbon content from steel. This process is suitable for secondary steelmaking industry which recycling steel scrap that has variety of carbon content in their feedstock. [7] This method aim to replace current conventional method that utilizing Basic Oxygen Furnace (BOF) to reduce carbon content of iron by blowing oxygen to make it react with carbon and forming CO2.

In electrorefining, decarburization process happened in electrochemical cell that composed of inert electrode, slag and steel. During the process, current passing through the cell and made slag and steel melted. Oxygen ion from slag decompose and oxidize carbon on steel and to form CO. That decarburizing reaction is occurred in three steps as follow. [7] (ads) means adsorbed intermediate

The total reaction from this cell is following this scheme [7]

The SiO2 is come from the slag, based on the reaction above, beside producing CO gas, this method also producing pure silicon (depending on the slag). The benefit of this direct decarburization process is it does not produce CO2 but CO which is not considered as greenhouse gas.

Related Research Articles

<span class="mw-page-title-main">Electrochemistry</span> Branch of chemistry

Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference and identifiable chemical change. These reactions involve electrons moving via an electronically-conducting phase between electrodes separated by an ionically conducting and electronically insulating electrolyte.

<span class="mw-page-title-main">Oxide</span> Chemical compound where oxygen atoms are combined with atoms of other elements

An oxide is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– ion with oxygen in the oxidation state of −2. Most of the Earth's crust consists of oxides. Even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a thin skin of Al2O3 that protects the foil from further oxidation.

<span class="mw-page-title-main">Electrolysis</span> Technique in chemistry and manufacturing

In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell. The voltage that is needed for electrolysis to occur is called the decomposition potential. The word "lysis" means to separate or break, so in terms, electrolysis would mean "breakdown via electricity".

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.

<span class="mw-page-title-main">Chalcopyrite</span> Copper iron sulfide mineral

Chalcopyrite ( KAL-kə-PY-ryte, -⁠koh-) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green-tinged black.

<span class="mw-page-title-main">Steelmaking</span> Process for producing steel from iron ore and scrap

Steelmaking is the process of producing steel from iron ore and/or scrap. In steelmaking, impurities such as nitrogen, silicon, phosphorus, sulfur and excess carbon are removed from the sourced iron, and alloying elements such as manganese, nickel, chromium, carbon and vanadium are added to produce different grades of steel.

<span class="mw-page-title-main">Industrial processes</span> Process of producing goods

Industrial processes are procedures involving chemical, physical, electrical, or mechanical steps to aid in the manufacturing of an item or items, usually carried out on a very large scale. Industrial processes are the key components of heavy industry.

<span class="mw-page-title-main">Ferromanganese</span> Alloy of iron and manganese

Ferromanganese is an alloy of iron and manganese, with other elements such as silicon, carbon, sulfur, nitrogen and phosphorus. The primary use of ferromanganese is as a type of processed manganese source to add to different types of steel, such as stainless steel. Global production of low-carbon ferromanganese reached 1.5 megatons in 2010.

Hydrometallurgy is a technique within the field of extractive metallurgy, the obtaining of metals from their ores. Hydrometallurgy involve the use of aqueous solutions for the recovery of metals from ores, concentrates, and recycled or residual materials. Processing techniques that complement hydrometallurgy are pyrometallurgy, vapour metallurgy, and molten salt electrometallurgy. Hydrometallurgy is typically divided into three general areas:

Pyrometallurgy is a branch of extractive metallurgy. It consists of the thermal treatment of minerals and metallurgical ores and concentrates to bring about physical and chemical transformations in the materials to enable recovery of valuable metals. Pyrometallurgical treatment may produce products able to be sold such as pure metals, or intermediate compounds or alloys, suitable as feed for further processing. Examples of elements extracted by pyrometallurgical processes include the oxides of less reactive elements like iron, copper, zinc, chromium, tin, and manganese.

The FFC Cambridge process is an electrochemical method for producing Titanium (Ti) from titanium oxide by electrolysis in molten calcium salts.

Decarburization is the process of decreasing carbon content, which is the opposite of carburization.

<span class="mw-page-title-main">Pidgeon process</span>

The Pidgeon process is a practical method for smelting magnesium. The most common method involves the raw material, dolomite being fed into an externally heated reduction tank and then thermally reduced to metallic magnesium using 75% ferrosilicon as a reducing agent in a vacuum. Overall the processes in magnesium smelting via the Pidgeon process involve dolomite calcination, grinding and pelleting, and vacuum thermal reduction. Besides the Pidgeon process, electrolysis of magnesium chloride for commercial production of magnesium is also used, at one point in time accounting for 75% of the world's magnesium production.

<span class="mw-page-title-main">Direct reduced iron</span> Newly mined and refined type of metal

Direct reduced iron (DRI), also called sponge iron, is produced from the direct reduction of iron ore into iron by a reducing gas which either contains elemental carbon or hydrogen. When hydrogen is used as the reducing gas there are no greenhouse gases produced. Many ores are suitable for direct reduction.

Deoxidization is a method used in metallurgy to remove the oxygen content during steel manufacturing. In contrast, antioxidants are used for stabilization, such as in the storage of food. Deoxidation is important in the steelmaking process as oxygen is often detrimental to the quality of steel produced. Deoxidization is mainly achieved by adding a separate chemical species to neutralize the effects of oxygen or by directly removing the oxygen.

<span class="mw-page-title-main">Aluminium smelting</span> Process of extracting aluminium from its oxide alumina

Aluminium smelting is the process of extracting aluminium from its oxide, alumina, generally by the Hall-Héroult process. Alumina is extracted from the ore bauxite by means of the Bayer process at an alumina refinery.

<span class="mw-page-title-main">Argon oxygen decarburization</span>

Argon oxygen decarburization (AOD) is a process primarily used in stainless steel making and other high grade alloys with oxidizable elements such as chromium and aluminium. After initial melting the metal is then transferred to an AOD vessel where it will be subjected to three steps of refining; decarburization, reduction, and desulfurization.

Zinc smelting is the process of converting zinc concentrates into pure zinc. Zinc smelting has historically been more difficult than the smelting of other metals, e.g. iron, because in contrast, zinc has a low boiling point. At temperatures typically used for smelting metals, zinc is a gas that will escape from a furnace with the flue gas and be lost, unless specific measures are taken to prevent it.

The salt extraction process is an electrolytic method which may be used to extract valuable metals from slag, low-grade ores, or other materials by using molten salts. This method was developed by S. Seetharaman, O. Grinder, L. Teng and X. Ge at the Royal Institute of Technology in Sweden as part of a large Steel Eco-Cycle Project in 2005.

Electrolytic iron is a form of high purity iron, obtained by electrolysis. It has a high purity greater than 99.95% with trace elements accounting for only a millionth of a decimal.

References

  1. ↑ "Electrometallurgy", Physical Chemistry of Metallurgical Processes, John Wiley & Sons, Ltd, pp. 523–557, 2016, doi:10.1002/9781119078326.ch12, ISBN   978-1-119-07832-6 , retrieved 2020-09-24
  2. 1 2 3 4 5 Popov, K. I. (Konstantin Ivanovich) (2002). Fundamental aspects of electrometallurgy. Djokić, Stojan S., Grgur, Branimir N., 1965-. New York: Kluwer Academic/Plenum Publishers. ISBN   0-306-47564-2. OCLC   51893969.
  3. ↑ D.R., George C. Marshall Space Flight Center Marshall Space Flight Center, AL 35812, National Aeronautics and Space Administration Washington, DC 20546-0001 Curreri, P.A. Ethridge, E.C. Hudson, S.B. Miller, T.Y. Grugel, R.N. Sen, S. Sadoway. Process Demonstration For Lunar In Situ Resource Utilization--Molten Oxide Electrolysis (MSFC Independent Research and Development Project No. 5-81). OCLC   703646739.{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)
  4. ↑ Allanore, Antoine; Yin, Lan; Sadoway, Donald R. (May 2013). "A new anode material for oxygen evolution in molten oxide electrolysis". Nature. 497 (7449): 353–356. Bibcode:2013Natur.497..353A. doi:10.1038/nature12134. hdl: 1721.1/82073 . ISSN   1476-4687. PMID   23657254. S2CID   4379353.
  5. ↑ Allanore, Antoine; Ortiz, Luis A; Sadoway, Donald R (2011-04-19), Neelameggham, Neale R.; Belt, Cynthia K.; Jolly, Mark; Reddy, Ramana G. (eds.), "Molten Oxide Electrolysis for Iron Production: Identification of Key Process Parameters for Largescale Development", Energy Technology 2011, Hoboken, NJ, USA: John Wiley & Sons, Inc., pp. 121–129, doi:10.1002/9781118061886.ch12, ISBN   978-1-118-06188-6 , retrieved 2022-11-22
  6. 1 2 "Decarbonizing Steel Production". Boston Metal. Retrieved 2022-11-22.
  7. 1 2 3 4 Judge, William D.; Paeng, Jaesuk; Azimi, Gisele (October 2022). "Electrorefining for direct decarburization of molten iron". Nature Materials. 21 (10): 1130–1136. Bibcode:2022NatMa..21.1130J. doi:10.1038/s41563-021-01106-z. ISSN   1476-4660. PMID   34580434. S2CID   237947963.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.