Electrometallurgy is a method in

metallurgy Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys. Metallurgy encompasses both the ...

that uses electrical energy to produce metals by electrolysis. It is usually the last stage in metal production and is therefore preceded by

pyrometallurgical 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 ...

or hydrometallurgical operations. 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).

Processes

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

Electrolysis In chemistry and manufacturing, electrolysis is a technique that uses Direct current, direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of c ...

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 ...

, the extraction of metal from ores * Electrorefining, the purification of metals. Metal powder production by electrodeposition is included in this category, or sometimes electrowinning, or a separate category depending on application. *

Electroplating Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the redox, reduction of cations of that metal by means of a direct current, direct electric cur ...

, the deposition of a layer of one metal on another *

Electroforming Electroforming is a metal forming process in which parts are fabricated through electrodeposition on a model, known in the industry as a mandrel. Conductive (metallic) mandrels are treated to create a mechanical parting layer, or are chemicall ...

, the manufacture of, usually thin, metal parts through electroplating *

Electropolishing Electropolishing principle: 1. Electrolyte 2. Cathode 3. Workpiece to polish (Anode) 4. Particle moving from the work-piece to the cathode 5. Surface before polishing 6. Surface after polishing Electropolishing, also known as electrochemical poli ...

, the removal of material from a metallic workpiece *

Etching Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio (incised) in the metal. In modern manufacturing, other chemicals may be used on other type ...

, industrially known to Wikipedia as

chemical milling Chemical milling or industrial etching is the subtractive manufacturing process of using baths of temperature-regulated etching chemicals to remove material to create an object with the desired shape. Other names for chemical etching inclu ...

Research trends

Molten oxide electrolysis

Molten Oxide

in steelmaking is utilizing electrons as the reducing agent instead of coke as in conventional

blast furnace A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. ''Blast'' refers to the combustion air being supplied above atmospheric pressure. In a ...

. For steel production, this method uses an inert anode (Carbon, Platinum, Iridium or Chromium-based alloy) 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. Then the molten iron ore decompose following this reaction: : 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 Greenhouse gas (GHG) emissions from human activities intensify the greenhouse effect. This contributes to climate change. Carbon dioxide (), from burning fossil fuels such as coal, petroleum, oil, and natural gas, is the main cause of climate chan ...

. 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 the Massachusetts-based Boston Metal company is in a process to scale up this technology to an industrial level.

Direct decarburization electrorefining

The purpose of this method is to reduce carbon content from steel. This process is suitable for secondary steelmaking industry which recycling steel

scrap Scrap consists of recyclable materials, usually metals, left over from product manufacturing and consumption, such as parts of vehicles, building supplies, and surplus materials. Unlike waste, scrap can have monetary value, especially recover ...

that has variety of carbon content in their feedstock. This method aim to replace current conventional method that utilizing

Basic Oxygen Furnace Basic oxygen steelmaking (BOS, BOP, BOF, or OSM), also known as Linz-Donawitz steelmaking or the oxygen converter process,Brock and Elzinga, p. 50. is a method of primary steelmaking in which carbon-rich molten pig iron is made into steel. Blowi ...

(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 occurs in three steps as follows: # # # ::(ads) = adsorbed intermediate The total reaction from this cell is: : The SiO₂ comes from the slag, based on the reaction above, besides producing CO gas. This method also produces pure silicon (depending on the slag). The benefit of this direct decarburization process is that it does not produce CO₂, but rather CO, which is not considered as greenhouse gas.

References

{{Authority control Chemical processes Electrolysis Metallurgical processes