Basic oxygen steelmaking (BOS, BOF, Linz-Donawitz-Verfahren, LD-converter) is a method of steelmaking in which carbon-rich molten iron is made into steel. In Chemistry, a base is most commonly thought of as an aqueous substance that can accept Protons This refers to the Brønsted-Lowry theory of acids and Steelmaking is the second step in producing Steel from Iron ore. Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 The process is an improvement over the historically important Bessemer process. The Bessemer process was the first inexpensive Industrial process for the mass-production of Steel from molten Pig iron. The LD-converter is named after the Austrian placenames Linz and Donawitz (a district of Leoben). Austria (Österreich ( officially the Republic of Austria (Republik Österreich Linz is the third largest city of Austria and capital of the state of Upper Austria (Oberösterreich Leoben is a city in Styria, in central Austria, located on the Mur river
By blowing oxygen through molten pig iron, the carbon content of the alloy is lowered and changes the material into low-carbon steel. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Pig iron is the intermediate product of Smelting Iron ore with coke, usually with Limestone as a flux An alloy is a Solid solution or Homogeneous mixture of two or more elements, at least one of which is a Metal, which itself has Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0
A typical BOS vessel holds about 280 tonnes of steel. This article is about the tonne or metric ton For other tons see Ton. The vessel is lined with heat-resistant refractory bricks that can withstand the high temperature of molten metal. A fire brick, firebrick, or refractory brick is a block of refractory Ceramic material used in lining Furnaces Kilns Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature
The basic oxygen steel-making process is as follows:
- Molten iron from a blast furnace is poured into a large refractory-lined container called a ladle;
- The metal in the ladle is sent directly for basic oxygen steelmaking or to a pretreatment stage. A blast furnace is a type of metallurgical Furnace used for Smelting to produce metals generally Iron. A refractory is a material that retains its strength at high Temperatures ASTM C71 defines refractories as "non-metallic materials having those chemical and physical In Foundry work a ladle is a container used to transport and pour out molten metals Pretreatment of the blast furnace metal is used to reduce the refining load of sulfur, silicon, and phosphorus. Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 In desulfurising pre treatment, a lance is lowered into the molten iron in the ladle and several hundred kilograms of powdered magnesium are added. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 Sulfur impurities are reduced to magnesium sulfide in a violent exothermic reaction. In Thermodynamics, the word exothermic "outside heating" describes a process or reaction that releases Energy usually in the form of Heat, but The sulfide is then raked off. Similar pretreatment is possible for desiliconisation and dephosphorisation using mill scale(iron oxide) and lime as reagents. The decision to pretreat depends on the quality of the blast furnace metal and the required final quality of the BOS steel.
- Filling the furnace with the ingredients is called charging. A furnace is a device used for Heating The name derives from Latin fornax, Oven. The BOS process is autogenous: the required thermal energy is produced during the process. Maintaining the proper charge balance, the ratio of hotmetal to scrap, is therefore very important. The BOS vessel is one-fifth filled with steel scrap. Molten iron from the ladle is added as required by the charge balance. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 A typical chemistry of hotmetal charged into the BOS vessel is: 4% C, 0. 2-0. 8%Si, 0. 08%-0. 18%P, and 0. 01-0. 04%S.
- The vessel is then set upright and a water-cooled lance is lowered down into it. The lance blows 99% pure oxygen onto the steel and iron, igniting the carbon dissolved in the steel and burning it to form carbon monoxide and carbon dioxide, causing the temperature to rise to about 1700 °C. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Carbon monoxide, with the chemical formula CO is a colorless odorless tasteless yet highly toxic Gas. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single This melts the scrap, lowers the carbon content of the molten iron and helps remove unwanted chemical elements. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 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. It is this use of oxygen instead of air that improves upon on the Bessemer process, for the nitrogen (and other gases) in air do not react with the charge as oxygen does.
- Fluxes (burnt lime or dolomite) are fed into the vessel to form slag which absorbs impurities of the steelmaking process. In Metallurgy, a flux is a chemical cleaning agent which facilitates Soldering, Brazing, and Welding by removing Oxidation from Lime is a general term for various naturally occurring Minerals and materials derived from them in which Carbonates Oxides and Hydroxides of Dolomite (ˈdɒləmaɪt is the name of a Sedimentary Carbonate rock and a Mineral, both composed Slag is the By-product of Smelting Ore to purify Metals They can be considered to be a mixture of metal Oxides however During blowing the metal in the vessel forms an emulsion with the slag, facilitating the refining process. Near the end of the blowing cycle, which takes about 20 minutes, the temperature is measured and samples are taken. The samples are tested and a computer analysis of the steel given within six minutes. A typical chemistry of the blown metal is 0. 3-0. 6%C, 0. 05-0. 1%Mn, . 01-0. 03%Si, 0. 01-0. 03%S and P.
- The BOS vessel is tilted again and the steel is poured into a giant ladle. In Foundry work a ladle is a container used to transport and pour out molten metals This process is called tapping the steel. The steel is further refined in the ladle furnace, by adding alloying materials to give the steel special properties required by the customer. An alloy is a Solid solution or Homogeneous mixture of two or more elements, at least one of which is a Metal, which itself has Sometimes argon or nitrogen gas is bubbled into the ladle to make sure the alloys mix correctly. This article pertains to the chemical element For other uses see Argon (disambiguation. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 The steel now contains 0. 1-1% carbon. The more carbon in the steel, the harder it is, but it is also more brittle and less flexible.
- After the steel is removed from the BOS vessel, the slag, filled with impurities, is poured off and cooled.
The first basic oxygen steelmaking process was the LD process developed in 1952 by voestalpine AG in Linz, Austria. Year 1952 ( MCMLII) was a Leap year starting on Tuesday (link will display full calendar of the Gregorian calendar. voestalpine AG is an international steel company based in Linz, Austria. Linz is the third largest city of Austria and capital of the state of Upper Austria (Oberösterreich Austria (Österreich ( officially the Republic of Austria (Republik Österreich Some major steelmaking companies in the US did not convert to this process for decades, with the last Bessemer converter still operating commercially until 1968. The Bessemer process was the first inexpensive Industrial process for the mass-production of Steel from molten Pig iron. Year 1968 ( MCMLXVIII) was a Leap year starting on Monday (link will display full calendar of the Gregorian calendar.
The LD process replaced both the previously common Siemens-Martin process, also known as the open-hearth process, and the Bessemer process. Open hearth furnaces are one of a number of kinds of Furnace where excess carbon and other impurities are burnt out of Pig iron to produce steel. Open hearth furnaces are one of a number of kinds of Furnace where excess carbon and other impurities are burnt out of Pig iron to produce steel. The Bessemer process was the first inexpensive Industrial process for the mass-production of Steel from molten Pig iron.
External links
- Basic Oxygen Steelmaking module at steeluniversity.org, including a fully interactive simulation
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