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62-552: The new city, RAZMIC (Ras Al Zour Mineral Industrial City), is planned to exploit the mineral deposites of phosphate and bauxite found within Saudi Arabia. Therefore, a di-ammonium phosphate (DAP) plant will be built, an aluminium smelter , an aluminium rolling mill, an ammonia plant, an alumina refinery and facilities to produce phosphoric and sulphuric acid . Power will be supplied by the 2,400 MW Ras Al-Khair Power and Desalination Plant . The official ground breaking for

124-471: A gas diffusion electrode . The amount of electrical energy that must be added equals the change in Gibbs free energy of the reaction plus the losses in the system. The losses can (in theory) be arbitrarily close to zero, so the maximum thermodynamic efficiency equals the enthalpy change divided by the free energy change of the reaction. In most cases, the electric input is larger than the enthalpy change of

186-444: A voltaic pile and placed the other ends in a tube filled with water. They noticed when the wires were brought together that each wire produced bubbles. One type was hydrogen, the other was oxygen. In 1785 a Dutch scientist named Martin van Marum created an electrostatic generator that he used to reduce tin, zinc and antimony from their salts using a process later known as electrolysis. Though he unknowingly produced electrolysis, it

248-479: A batch process, with the aluminium deposited at the bottom of the pots and periodically siphoned off. Particularly in Australia these smelters are used to control electrical network demand, and as a result power is supplied to the smelter at a very low price. However power must not be interrupted for more than 4–5 hours, since the pots have to be repaired at significant cost if the liquid metal solidifies. Aluminium

310-481: A ceramic matrix of nickel ferrite. Unfortunately, as the number of anode components increases , the structure of the anode becomes more unstable. As a result. cermet anodes also suffer from corrosion issues during reduction. Aluminium smelting is highly energy intensive, and in some countries is economical only if there are inexpensive sources of electricity. In some countries, smelters are given exemptions to energy policy like renewable energy targets . To reduce

372-404: A compound, electrical energy is released. Humphry Davy would go on to create Decomposition Tables from his preliminary experiments on Electrolysis. The Decomposition Tables would give insight on the energies needed to break apart certain compounds. In 1817 Johan August Arfwedson determined there was another element, lithium, in some of his samples; however, he could not isolate the component. It

434-475: A distance such that a current flows between them through the electrolyte and are connected to the power source which completes the electrical circuit . A direct current supplied by the power source drives the reaction causing ions in the electrolyte to be attracted toward the respective oppositely charged electrode. Electrodes of metal , graphite and semiconductor material are widely used. Choice of suitable electrode depends on chemical reactivity between

496-680: A gaseous fluorine pure element. Before he used hydrogen fluoride, Henri Moissan used fluoride salts with electrolysis. Thus on June 28, 1886, he performed his experiment in front of the Académie des sciences to show his discovery of the new element fluorine. While trying to find elemental fluorine through electrolysis of fluoride salts, many chemists perished including Paulin Louyet and Jérôme Nicklès. In 1886 Charles Martin Hall from America and Paul Héroult from France both filed for American patents for

558-791: A major export hub for aluminium products and ammonium phosphate. In July 2011, King Abdullah changed the name of Ras Az-Zour to Ras Al-Khair (with Khair meaning light or bright to have a more positive naming), according to a statement by President of the Royal Commission for Jubail and Yanbu Prince Saud bin Abdullah bin Thunayan to the Saudi Press Agency on 6 July 2011. 27°27′21″N 49°18′01″E  /  27.4557°N 49.3002°E  / 27.4557; 49.3002 Aluminium smelter Aluminium smelting

620-496: A melting temperature of 1010 °C, and it forms a eutectic with 11% alumina at 960 °C. In industrial cells the cryolite ratio is kept between 2 and 3 to decrease its melting temperature to 940–980 °C. Cathode: Carbon cathodes are essentially made of anthracite, graphite and petroleum coke, which are calcined at around 1200 °C and crushed and sieved prior to being used in cathode manufacturing. Aggregates are mixed with coal-tar pitch, formed, and baked. Carbon purity

682-487: A mixture of CO and CO 2 is produced. Thus the idealised overall reactions may be written as By increasing the current density up to 1 A/cm , the proportion of CO 2 increases and carbon consumption decreases. As three electrons are needed to produce each atom of aluminium, the process consumes a large amount of electricity. For this reason aluminium smelters are sited close to sources of inexpensive electricity, such as hydroelectric . Electrolyte: The electrolyte

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744-459: A paste with a doughy consistency. This material is most often vibro-compacted but in some plants pressed. The green anode is then sintered at 1100–1200 °C for 300–400 hours, without graphitization , to increase its strength through decomposition and carbonization of the binder. Higher baking temperatures increase the mechanical properties and thermal conductivity, and decrease the air and CO 2 reactivity. The specific electrical resistance of

806-463: A permanent mark or logo. Using a cell containing inert platinum electrodes, electrolysis of aqueous solutions of some salts leads to the reduction of the cations (such as metal deposition with, for example, zinc salts) and oxidation of the anions (such as the evolution of bromine with bromides). However, with salts of some metals (such as sodium) hydrogen is evolved at the cathode, and for salts containing some anions (such as sulfate SO 4 ) oxygen

868-437: A product out of the electrolyte). The quantity of the products is proportional to the current, and when two or more electrolytic cells are connected in series to the same power source, the products produced in the cells are proportional to their equivalent weight . These are known as Faraday's laws of electrolysis . Each electrode attracts ions that are of the opposite charge . Positively charged ions ( cations ) move towards

930-405: A quantity of fluoride waste: perfluorocarbons and hydrogen fluoride as gases, and sodium and aluminium fluorides and unused cryolite as particulates. This can be as small as 0.5 kg per tonne of aluminium in the best plants in 2007, up to 4 kg per tonne of aluminium in older designs in 1974. Unless carefully controlled, hydrogen fluorides tend to be very toxic to vegetation around

992-423: A specific situation in aluminium smelting and depending on the type of anode, aluminium smelting is divided in two different technologies; “Soderberg” and “prebaked” anodes. Anodes are also made of petroleum coke, mixed with coal-tar-pitch, followed by forming and baking at elevated temperatures. The quality of anode affects technological, economical and environmental aspects of aluminium production. Energy efficiency

1054-405: Is a molten bath of cryolite (Na 3 AlF 6 ) and dissolved alumina. Cryolite is a good solvent for alumina with low melting point, satisfactory viscosity, and low vapour pressure. Its density is also lower than that of liquid aluminium (2 vs 2.3 g/cm ), which allows natural separation of the product from the salt at the bottom of the cell. The cryolite ratio (NaF/AlF 3 ) in pure cryolite is 3, with

1116-463: Is altered in the process. For example, the electrolysis of brine produces hydrogen and chlorine gases which bubble from the electrolyte and are collected. The initial overall reaction is thus: The reaction at the anode results in chlorine gas from chlorine ions: The reaction at the cathode results in hydrogen gas and hydroxide ions: Without a partition between the electrodes, the OH ions produced at

1178-495: Is charged, its redox reaction is run in reverse and the system can be considered as an electrolytic cell . The chloralkali process is a large scale application of electrolysis. This technology supplies most of the chlorine and sodium hydroxide required by many industries. The cathode is a mixed metal oxide clad titanium anode (also called a dimensionally stable anode). Many organofluorine compounds are produced by electrofluorination . One manifestation of this technology

1240-429: 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." The word "electrolysis" was introduced by Michael Faraday in 1834, using

1302-557: Is completed. The town is served by King Fahd International Airport , the terminal is at a driving distance of 180 km (112 mi) to the south. Ras Az-Zour will be linked by the Saudi Railways Organization to the bauxite mines at Zabirah with a new railway line branch of the North-South Project. Later the line will be extended to meet the line from Riyadh via Buraidah to Haditha at

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1364-414: Is deposited over a substrate material. Electroplating is used in many industries for either functional or decorative purposes, as in-vehicle bodies and nickel coins. In Electrochemical machining , an electrolytic cathode is used as a shaped tool for removing material by anodic oxidation from a workpiece. ECM is often used as a technique for deburring or for etching metal surfaces like tools or knives with

1426-475: Is evolved at the anode. In both cases, this is due to water being reduced to form hydrogen or oxidized to form oxygen. In principle, the voltage required to electrolyze a salt solution can be derived from the standard electrode potential for the reactions at the anode and cathode. The standard electrode potential is directly related to the Gibbs free energy , Δ G , for the reactions at each electrode and refers to an electrode with no current flowing. An extract from

1488-637: Is not as stringent as for anode, because metal contamination from cathode is not significant. Carbon cathode must have adequate strength, good electrical conductivity and high resistance to wear and sodium penetration. Anthracite cathodes have higher wear resistance and slower creep with lower amplitude [15] than graphitic and graphitized petroleum coke cathodes. Instead, dense cathodes with more graphitic order have higher electrical conductivity, lower energy consumption [14], and lower swelling due to sodium penetration. Swelling results in early and non-uniform deterioration of cathode blocks. Anode: Carbon anodes have

1550-434: Is optional to keep the products from diffusing to the vicinity of the opposite electrode. The electrolyte is a chemical substance which contains free ions and carries electric current (e.g. an ion-conducting polymer , solution, or a ionic liquid compound). If the ions are not mobile, as in most solid salts , then electrolysis cannot occur. A liquid electrolyte is produced by: The electrodes are immersed separated by

1612-425: Is produced by electrolytic reduction of aluminium oxide dissolved in molten cryolite . At the same time the carbon electrode is oxidised, initially to carbon monoxide Although the formation of carbon monoxide (CO) is thermodynamically favoured at the reaction temperature, the presence of considerable overvoltage (difference between reversible and polarization potentials) changes the thermodynamic equilibrium and

1674-430: Is related to the nature of anode materials, as well as the porosity of baked anodes. Around 10% of cell power is consumed to overcome the electrical resistance of prebaked anode (50–60 μΩm). Carbon is consumed more than theoretical value due to a low current efficiency and non-electrolytic consumption. Inhomogeneous anode quality due to the variation in raw materials and production parameters also affects its performance and

1736-462: Is the Simons process , which can be described as: In the course of a typical synthesis, this reaction occurs once for each C–H bond in the precursor. The cell potential is maintained near 5–6 V . The anode , the electrocatalyst, is nickel -plated. Acrylonitrile is converted to adiponitrile on an industrial scale via electrocatalysis. Electroplating , where a thin film of metal

1798-454: Is the difference of the electrode potentials as calculated using the Nernst equation . Applying additional voltage, referred to as overpotential , can increase the rate of reaction and is often needed above the thermodynamic value. It is especially necessary for electrolysis reactions involving gases, such as oxygen , hydrogen or chlorine . Oxidation of ions or neutral molecules occurs at

1860-548: 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 . This is an electrolytic process, so an aluminium smelter uses huge amounts of electric power; smelters tend to be located close to large power stations, often hydro-electric ones, in order to hold down costs and reduce

1922-568: The Greek words ἤλεκτρον [ɛ̌ːlektron] "amber", which since the 17th century was associated with electrical phenomena , and λύσις [lýsis] meaning "dissolution". Nevertheless, electrolysis, as a tool to study chemical reactions and obtain pure elements , precedes the coinage of the term and formal description by Faraday. In the early nineteenth century, William Nicholson and Anthony Carlisle sought to further Volta's experiments. They attached two wires to either side of

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1984-451: The anode . For example, it is possible to oxidize ferrous ions to ferric ions at the anode: Reduction of ions or neutral molecules occurs at the cathode . It is possible to reduce ferricyanide ions to ferrocyanide ions at the cathode: Neutral molecules can also react at either of the electrodes. For example: p -benzoquinone can be reduced to hydroquinone at the cathode: In the last example, H ions (hydrogen ions) also take part in

2046-599: The aluminium project by the Saudi Arabian Mining Company (MA'ADEN) and Alcoa was on 19 June 2010. The project was scheduled to be completed by 2014. Among other projects a residential village for the MAADEN employees was built with 500 housing units. The King Salman Global Maritime Industries Complex is under construction in Ras Al-Khair, and will be the largest shipyard in the world when it

2108-454: The cathode are free to diffuse throughout the electrolyte to the anode. As the electrolyte becomes more basic due to the production of OH , less Cl 2 emerges from the solution as it begins to react with the hydroxide producing hypochlorite (ClO ) at the anode: The more opportunity the Cl 2 has to interact with NaOH in the solution, the less Cl 2 emerges at the surface of the solution and

2170-427: The cathode, the rate of the latter depends on factors such as diffusion and the surface area of the cathode in contact with the electrolyte. Decomposition potential or decomposition voltage refers to the minimum voltage (difference in electrode potential ) between anode and cathode of an electrolytic cell that is needed for electrolysis to occur. The voltage at which electrolysis is thermodynamically preferred

2232-507: The cell stability. Prebaked consumable carbon anodes are divided into graphitized and coke types. For manufacturing of the graphitized anodes, anthracite and petroleum coke are calcined and classified. They are then mixed with coal-tar pitch and pressed. The pressed green anode is then baked at 1200 °C and graphitized. Coke anodes are made of calcined petroleum coke, recycled anode butts, and coal-tar pitch (binder). The anodes are manufactured by mixing aggregates with coal tar pitch to form

2294-575: The coke-type anodes is higher than that of the graphitized ones, but they have higher compressive strength and lower porosity. Soderberg electrodes (in-situ baking), used for the first time in 1923 in Norway, are composed of a steel shell and a carbonaceous mass which is baked by the heat being escaped from the electrolysis cell. Soderberg Carbon-based materials such as coke and anthracite are crushed, heat-treated, and classified. These aggregates are mixed with pitch or oil as binder, briquetted and loaded into

2356-422: The desirable properties of both; the electrical conductivity and toughness of the metal and stability of the ceramic. These anodes often consist of a combination of the above metal and ceramic materials. In industry, Alcoa and Rio Tinto have formed a joint venture, Elysis, to commercialize inert anode technology developed by Alcoa. The inert anode is a cermet material, a metallic dispersion of copper alloy in

2418-489: The electrode and electrolyte and manufacturing cost. Historically, when non-reactive anodes were desired for electrolysis, graphite (called plumbago in Faraday's time) or platinum were chosen. They were found to be some of the least reactive materials for anodes. Platinum erodes very slowly compared to other materials, and graphite crumbles and can produce carbon dioxide in aqueous solutions but otherwise does not participate in

2480-409: The electrolysis of copper and zinc . Electrolysis is the passing of a direct electric current through an electrolyte which is producing chemical reactions at the electrodes and decomposition of the materials. The main components required to achieve electrolysis are an electrolyte , electrodes, and an external power source. A partition (e.g. an ion-exchange membrane or a salt bridge )

2542-724: The electrolysis of aluminum, with Héroult submitting his in May, and Hall, in July. Hall was able to get his patent by proving through letters to his brother and family evidence that his method was discovered before the French patent was submitted. This became known as the Hall–Héroult process which benefited many industries because aluminum's price then dropped from four dollars to thirty cents per pound. In 1902 Polish engineer and inventor Stanisław Łaszczyński filed for and obtained Polish patent for

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2604-474: The electrolyte, and are therefore not consumed during the reduction process. Because the anode does not contain carbon, carbon dioxide is not produced. Through a review of literature, Haradlsson et al. found that inert anodes reduced the green house gas emissions of the aluminum smelting process by approximately 2 tonnes CO2eq/ tonne Al. Ceramic anode materials include Ni-Fe, Sn, and Ni-Li based oxides. These anodes show promise as they are extremely stable during

2666-413: The electron-providing (negative) cathode. Negatively charged ions ( anions ) move towards the electron-extracting (positive) anode. In this process electrons are effectively introduced at the cathode as a reactant and removed at the anode as a product . In chemistry, the loss of electrons is called oxidation , while electron gain is called reduction . When neutral atoms or molecules, such as those on

2728-441: The energy cost of aluminum reduction up to 30% by lowering the voltage needed for reduction to occur. Applying these two technologies at the same times allows the anode-cathode distance to be minimized which decreases restive losses. Electrolysis In chemistry and manufacturing , electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction . Electrolysis

2790-543: The energy cost of the smelting process, alternative electrolytes such as Na3AlF6 are being investigated that can operate at a lower temperature. However, changing the electrolyte changes the kinetics of the liberated oxygen from the Al 2 O 3 ore. This change in bubble formation can alter the rate the anode reacts with Oxygen or the electrolyte and effectively change the efficiency of the reduction process. Inert anodes, used in tandem with vertical electrode cells, can also reduce

2852-402: The faster the production of hypochlorite progresses. This depends on factors such as solution temperature, the amount of time the Cl 2 molecule is in contact with the solution, and concentration of NaOH. Likewise, as hypochlorite increases in concentration, chlorates are produced from them: Other reactions occur, such as the self-ionization of water and the decomposition of hypochlorite at

2914-400: The overall carbon footprint . Smelters are often located near ports, since many smelters use imported alumina. The Hall-Héroult electrolysis process is the major production route for primary aluminium. An electrolytic cell is made of a steel shell with a series of insulating linings of refractory materials. The cell consists of a brick-lined outer steel shell as a container and support. Inside

2976-650: The plants. The Soderberg process which bakes the Anthracite/pitch mix as the anode is consumed, produces significant emissions of polycyclic aromatic hydrocarbons as the pitch is consumed in the smelter. The linings of the pots end up contaminated with cyanide-forming materials; Alcoa has a process for converting spent linings into aluminium fluoride for reuse and synthetic sand usable for building purposes and inert waste. Inert anodes are non-carbon based alternatives to traditional anodes used during aluminum reduction. These anodes do not chemically react with

3038-406: The principal formulation and the fundamental reactions occurring on their surface are the same. An aluminium smelter consists of a large number of cells (pots) in which the electrolysis takes place. A typical smelter contains anywhere from 300 to 720 pots, each of which produces about a ton of aluminium a day, though the largest proposed smelters are up to five times that capacity. Smelting is run as

3100-406: The ratio of ozone to oxygen produced at the anode in the electrolysis of an aqueous acidic solution such as dilute sulphuric acid. Electrolysis of ethanol with pulsed current evolves an aldehyde instead of primarily an acid. Galvanic cells and batteries use spontaneous, energy-releasing redox reactions to generate an electrical potential that provides useful power. When a secondary battery

3162-439: The reaction and are provided by the acid in the solution, or by the solvent itself (water, methanol, etc.). Electrolysis reactions involving H ions are fairly common in acidic solutions. In aqueous alkaline solutions, reactions involving OH (hydroxide ions) are common. Sometimes the solvents themselves (usually water) are oxidized or reduced at the electrodes. It is even possible to have electrolysis involving gases, e.g. by using

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3224-438: The reaction, so some energy is released in the form of heat. In some cases, for instance, in the electrolysis of steam into hydrogen and oxygen at high temperature, the opposite is true and heat energy is absorbed. This heat is absorbed from the surroundings, and the heating value of the produced hydrogen is higher than the electric input. Pulsating current results in products different from DC. For example, pulsing increases

3286-502: The reaction. Cathodes may be made of the same material, or they may be made from a more reactive one since anode wear is greater due to oxidation at the anode. The key process of electrolysis is the interchange of atoms and ions by the removal or addition of electrons due to the applied potential. The desired products of electrolysis are often in a different physical state from the electrolyte and can be removed by mechanical processes (e.g. by collecting gas above an electrode or precipitating

3348-407: The reduction process at normal operating temperatures (~1000 °C), ensuring that the Al is not contaminated. The stability of these anodes also allows them to be used with a range of electrolytes. However, ceramic anodes suffer from poor electrical conductivity and low mechanical strength. Alternatively metal anodes boast high mechanical strength and conductivity but tend to corrode easily during

3410-430: The reduction process. Some material systems that are used in inert metal anodes include Al-Cu, Ni-Cu, and Fe-Ni-Cu systems. Additional additives such as Sn, Ag, V, Nb, Ir, Ru can be included in these systems to form non reactive oxides on the anode surface, but this significantly increases the cost and embodied energy of the anode. Cermet anodes are the combination of a metal and ceramic anode, and aim to take advantage of

3472-418: The shell, cathode blocks are cemented together by ramming paste. The top lining is in contact with the molten metal and acts as the cathode. The molten electrolyte is maintained at high temperature inside the cell. The prebaked anode is also made of carbon in the form of large sintered blocks suspended in the electrolyte. A single Soderberg electrode or a number of prebaked carbon blocks are used as anode, while

3534-437: The shell. Temperature increases bottom to the top of the column and in-situ baking takes place as the anode is lowered into the bath. Significant amount of hydrocarbons are emitted during baking which is a disadvantage of this type of electrodes. Most of the modern smelters use prebaked anodes since the process control is easier and a slightly better energy efficiency is achieved, compared to Soderberg anodes. The process produces

3596-529: The so-called Zubairah Junction. As part of the Saudi Landbridge Project another line will connect the new port to Jubail and to Dammam . Thus Ras Al-Zour will be connected to the bauxite mine near Zabirah, the phosphate deposits near Jalamid and the agricultural center at Al-Basyata as well as to the oil processing facilities via the Jubail line. The proposed seaport is thought to become

3658-482: The surface of an electrode, gain or lose electrons they become ions and may dissolve in the electrolyte and react with other ions. When ions gain or lose electrons and become neutral, they will form compounds that separate from the electrolyte. Positive metal ions like Cu deposit onto the cathode in a layer. The terms for this are electroplating , electrowinning , and electrorefining . When an ion gains or loses electrons without becoming neutral, its electronic charge

3720-619: The time of Maxwell and Faraday, concerns came about for electropositive and electronegative activities. In November 1875, Paul Émile Lecoq de Boisbaudran discovered gallium using electrolysis of gallium hydroxide, producing 3.4 mg of gallium. The following December, he presented his discovery of gallium to the Académie des sciences in Paris. On June 26, 1886, Ferdinand Frederick Henri Moissan finally felt comfortable performing electrolysis on anhydrous hydrogen fluoride to create

3782-490: Was not until 1800 when William Nicholson and Anthony Carlisle discovered how electrolysis works. In 1791 Luigi Galvani experimented with frog legs. He claimed that placing animal muscle between two dissimilar metal sheets resulted in electricity. Responding to these claims, Alessandro Volta conducted his own tests. This would give insight to Humphry Davy 's ideas on electrolysis. During preliminary experiments, Humphry Davy hypothesized that when two elements combine to form

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3844-454: Was not until 1821 that William Thomas Brande used electrolysis to single it out. Two years later, he streamlined the process using lithium chloride and potassium chloride with electrolysis to produce lithium and lithium hydroxide. During the later years of Humphry Davy's research, Michael Faraday became his assistant. While studying the process of electrolysis under Humphry Davy, Michael Faraday discovered two laws of electrolysis . During

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