# blast furnace gunning process

Iron ore that contains a lower iron content must be processed or beneficiated to increase its iron content. 5. The flow rate of molten metal and slag through the trough system increase many times in case of larger blast furnaces. The blast furnace process is characterised by the variety and complexity of the phenomena of gas dynamics, charge transfer, heat transfer, recovery, softening, and other phenomena. Use of Blast Furnace Products. This zone of the blast furnace is therefore called the preheating zone. If the temperature is lowered, however, part of the water bound in air condenses and the liquid content of the ground rises. 8. gunning process in blast furnace in steel plant..... Tibetan Music, Healing Music, Relaxation Music, Chakra, Relaxing Music for Stress Relief, 2853C - Duration: 6:00:22. 3~Fe_2O_3 &~+~ CO  &&\rightarrow~ 2~Fe_3O_4 &&+ ~CO_2 ~~~~~~ \text{(hematite} \rightarrow \text{magnetite)} \\[5px] At the latest, however, when the melting process occurs in the deeper and hotter zones of the blast furnace, iron ores can be almost completely reduced. 3 Fe &~+~ C &&\rightarrow~ Fe_3C  \\[5px] Hot‐Metal Desulfurization Iron is made by reacting iron ore (iron oxide and impurities), coke (a reductant) and limestone (CaCO 3) in a blast furnace. However, this dynamic equilibrium can be shifted in favour of or at the expense of the liquid water, depending on the temperature. The corresponding chemical reactions are as follows: \begin{align} It has a high carbon content of about 4.5 %. 1. 1200 °C (see iron-carbon phase diagram). The first blast furnaces appeared in the 14th century and produced one ton per day. The iron ore is dressed or crushed into 0.5-1 in. refra.com Für den Bereich der Hochofenschachtzustellung wurden alkali- und CO-resistente Produkte in allen Installationstechnologien (Gießen, Trockenspritzen, Jetcasting) entwickelt und erprobt. Modern blast furnaces require around 350 kg of coke to melt one tonne of pig iron. The hearth zone is … The fracture surface of a metastable solidified pig iron, on the other hand, has a whitish shine and is therefore also called white pig iron. This leads to a temperature increase of up to 2000 °C. blast furnace technology 9 top charging a blast furnace starts on the ground. Blast Furnace Process. In the direct reduction zone, carbon takes part directly in the reduction of iron oxides! Gradually all the iron ore is reduced, carburized and melted. Blast Furnace Productivity Criteria. Graphite formation is also favoured by a relatively low manganese content and slow cooling. Seven Refractories and its daughter company Refracon Installations completed the repair of hot blast stove in MMK from September, 25th to 28th. The blast furnace process has been the primary method for producing iron for many decades. This ore is crushed and ground into a powder so the waste material called gangue can be removed. As the blast furnace gas is drawn back into the hot blast stove, air is admitted through the peep sights and stove burner, and the operator makes certain that the gas burns in the stove. Blast furnaces are furnaces lined with refractory to withstand the high temperatures and the abrasive materials being processed. Thanks, Your email address will not be published. Iron Making in Mini Blast Furnace (MBF) The Blast Furnace ironmaking process had, until recently, been the unchallenged method of making hot metal on a large scale. 7. In the melting zone the iron begins to melt and forms strongly carbon-containing pig iron! The refractory lining is cooled to further enhance the protection against the dispatch … The consistency of the iron is therefore still solid. Amongst all the ironmaking processes, the Blast Furnace technology, which has been around the longest, still holds the dominant position. If you continue to use this website, we will assume your consent and we will only use personalized ads that may be of interest to you. Blast furnace stack The refractory material is subjected to attack from CO atmosphere, alkalines, and mechanical wear. Now the inner ore layers also come into contact with the carbon or the carbon monoxide gas and can be reduced to iron and then carburized. \end{align}. The direct reduction can again be divided into intermediate steps in which the iron content in the ores increases in each case: \begin{align} However, the heat released is sufficient to supply heat for the first two endothermic reactions. In the field of blast furnace shaft lining, alkali and CO-resistant products have been developed and tested in all installation technologies (casting, dry gunning, jetcasting). The Cowper on August 5th has been set and put on heating up. Till 1990, the blast furnace route of ironmaking had about 97% (527mt) share of global iron production. In the carburizing zone, the reduced iron is enriched with carbon and forms the intermediate compound iron carbide ($$Fe_3C$$, cementite)! To generate the necessary heat and the reducing carbon monoxide gas ($$CO$$), the coke is burnt in the lower part of the blast furnace with the supply of the hot-blast. \end{align}. The blast furnace is a refractory-lined circular shaft 100 to 200 feet high, with an internal diameter between 20 and 45 feet. Specialists of both companies led and supervised the installation of 40 tons of Seven Gun 82 NX in the burning chamber/burning duct of hot blast stove n29 – blast furnace 9. This combustion is very strongly exothermic, i.e. The reduced admixtures in the blast furnace then react with the added flux in the charge and are bound in the resulting slag. What is “grey pig iron” and “white pig iron”? For this reason, the iron ores are also processed as porous as possible in the form of sinter and pellets. Blast Furnace and Process Description 3D Model The preheated air (1000–1300 °C) is blown through it. Iron making blast furnace consists of several zones a crucible shaped hearth at the bottom of the furnace, an intermediate zone … As long as your consent is not given, no ads will be displayed. Other elements such as titanium, copper, etc. The use of carbon as a reducing agent is not only due to its high availability but as a gaseous substance carbon monoxide has the advantage that it can penetrate the porous ores well and react with the iron oxides. This website uses cookies. The carbon ($$C$$) contained in the coke initially reacts with the atmospheric oxygen in the hot-blast ($$O_2$$) according to the following chemical equation to carbon dioxide ($$CO_2$$): \begin{align} In the indirect reduction zone, the iron oxide contained in the iron ores is reduced by carbon monoxide gas, whereby the iron ores are not melted! This module introduces the learner to the operation of the blast furnace for the transformation of iron ore to molten iron. The oxygen of the blast burns coke to CO and several combustion zones, one in front of each tuyere, exist in the tuyere zone. In order to keep the heat input as low as possible for energetic reasons, as little gangue as possible should be contained in the ores. Effective Utilization of Energy. Lining thickness be obtained from registration re-sult and is illustrated in Sec. It becomes obvious that at temperatures above 1000 °C carbon dioxide disintegrates almost exclusively in favour of carbon monoxide. The carbon ($$C$$) is oxidized to carbon monoxide ($$CO$$) by the absorption of oxygen ($$O$$). Carbon not only provides the necessary heat to melt the iron ore but also serves in a special way as a reducing agent to reduce the iron oxides to iron! More than 90 % of the pig iron is beeing tapped as white pig iron (“steel pig iron”) and processed in liquid form in ironworks to the actual steel by special after-treatment processes. Although the carbon reduces the iron oxides and produces iron, the iron formed is partially enriched with carbon itself. Too low a temperature would again mean the back reaction (indicated by the double arrow in the chemical equation) of the carbon monoxide to carbon dioxide. Most possible service life of the blast furnace shaft linings as well as runner systems, short repairing times and full-service solutions. Combustion process. With metastable solidification, the iron carbide compound cementite is formed (white pig iron)! 3 Fe_2O_3 &~+~ C &&\rightarrow~ 2~Fe_3O_4 &&+ ~CO ~~~~~~ \text{(hematite} \rightarrow \text{magnetite)} \\[5px] Over time, a balance between the water that is still liquid and the water contained in the air will develop. Then the magnetite is reduced to so-called wüstite ($$FeO$$) before it is finally reduced to iron ($$Fe$$): \begin{align} The formation of carbon monoxide is endothermic, i.e. To get good campaign life special attention must be given to both refractory lining and design i.e. Why is carbon used for the blast furnace process? \label{kohlendioxid} Due to the direct reduction of iron oxides by carbon, one also speaks of a direct reduction. & CO_2 + C  \rightleftharpoons 2~CO ~~~ \text{(endotherm)} \\[5px] Iron ores with lower iron content such as taconite are first processed to concentrate the iron level and drive off volatile impurities. With a relatively low silicon content, on the other hand, cementite precipitation is preferred when the pig iron solidifies. a blast furnace is different due to the very nature of its geometry and also pyrometallurgical process occurring at different stages (see adjacent Blast Furnace figures). In both cases the iron oxide is reduced to iron. But precisely this carbon monoxide is necessary for the reduction of iron oxides and must be produced in sufficient quantities. Fe_3O_4 &~+~ C &&\rightarrow~ 3~FeO &&+ ~CO ~~~~~~ \text{(magnetite} \rightarrow \text{wüstite)} \\[5px] The carbon monoxide gas ($$CO$$) is oxidized to carbon dioxide ($$CO_2$$) by absorbing the oxygen contained in the iron oxide ($$O$$). An excessive drop in temperature must be avoided, however, as the reaction of carbon dioxide to carbon monoxide only takes place at sufficiently high temperatures. How important is the “Boudouard reaction” for the blast furnace process? The silicon, manganese and phosphorus compounds (and many other compounds) contained in the gangue are also reduced endothermically. The carburization lowers the solidification temperature of the iron! with energy absorption, so that the temperature of the gas drops to about 1700 °C. The Blast Furnace is a heat based machine using solely for the creation of Steel. If the iron ores, which have not yet been reduced, move further down in the blast furnace, then the carbon can also directly reduce the iron oxides contained in the ore due to the high temperatures. With a daily production of 10,000 tons, this results in a coke input of 3,500 tons per day! \end{align}. The chemical processes are discussed in more detail in the chapter on blast furnace processes. To start the process, the Blast Furnace needs an input of Heat through the orange square on the side of the block. Refractory lining of blast furnace A modern blast furnace (BF) is refractory lined to protect the furnace shell from the high temperatures and abrasive materials inside the furnace. The individual chemical processes in the blast furnace are described in more detail in the following sections. Outline of a Blast Furnace Construction. CO 2 capture from the overall flue gas stream. Due to the higher density of the pig iron, the pig iron can be cut off at the lowest point of the blast furnace (called tapping). a blast furnace without any further processing. Therefore the solidified pig iron is also called grey pig iron. However, the BF process relies heavily on metallurgical coke and involves cokemaking and sintering operations, which often attract serious environmental concerns. Blast furnace gunning process. In the blast furnace there are more monolithic refractory products in continuous operation than at any other stage in the steel production process - excluding new linings and interim repairs. Further accompanying elements are listed below, although the composition may vary considerably depending on the type of pig iron. 2. At this temperature, the filled charge are first dried and preheated. \label{indirekt} The situation can be illustrated by the evaporation of water in a closed room filled with air. If the air is completely saturated with water, it cannot absorb water any further and a remainder of liquid water remains in the room. Globally, however, an equilibrium between these phases or between the reaction and its reverse reactionof liquid and air-bound water will occur. Graphite precipitation is preferred for high silicon concentrations. The blast furnace is the first step in producing steel from iron oxides. This type of solidification is therefore also referred to as stable solidification. Blast Furnace Special area. This requires an element that binds oxygen more strongly than iron. \label{kohlenmonoxid} The project realized in August, during capital repair of blast furnace № 5 NLMK, included full service range, from the cleaning of collapsed brick lining until the restoration of protecting layer on the wall and pipe valves by gunning. Save my name, email, and website in this browser for the next time I comment. \label{aufkohlen} The reaction of carbon dioxide and carbon to carbon monoxide and its reverse reaction is temperature-dependent and is described by the so-called Boudouard reaction. However, the demand for grey pig iron accounts for only a small part. This produces iron carbide $$Fe_3C$$, also known as cementite. Ironmaking Blast Furnace. ing points taking from the speciﬁc geometry of the blast . The trough design is based on fluid flow characteristics along with thermo-chemical reactions. This is exactly what carbon can do as a reducing agent. Furnace runs rough and very loud Electric arc is complete covered Best energy input cos φ = 0,9 High seondary voltage, long arcs low electrode consumption fast process, Tap to Tap < 60 min Best wear protection for refractory Furnace runs smooth and quiet 30 Slag systems c-steel versus stainless-steel Therefore, the Blast Furnace Bottom, Hearth, Taphole, Tuyeres, Bosh, Belly, Stack, Cast house, Blast Furnace Stoves all require different quality of refract ories depending on the respective application conditions. The molten pig iron finally collects in the hearth of the blast furnace together with the slag, which is also liquid. 6. The blast furnance route, so called integration route, is still the most significant method in order to produce pig iron. The unmelted iron ores still contain non-reduced iron oxides. furnace. FeO &~+~ CO &&\rightarrow~ Fe &&+ ~CO_2 ~~~~~~ \text{(wüstite} \rightarrow \text{iron)} \\[5px] This article provides answers to the following questions, among others: The iron in the processed ores must be dissolved out by chemical processes. What is the difference between metastable and stable solidification? At high temperatures, carbon reacts predominantly with carbon dioxide to form carbon monoxide (as an important reducing agent). What chemical processes distinguish indirect reduction from direct reduction of iron ores? Taphole mixes, runner mixes, assembly parts or preshapes (for example skimmer, tipping trough) are heavily-used refractory products in the production of pig steel. The blast furnace requires different types of refractory products with resistance to thermo-mechanical and thermo-chemical reactions. At lower temperatures, the reduction takes place indirectly with the help of the carbon monoxide gas formed during combustion (indirect reduction). Due to the reduction of the solidificatoin point by diffused carbon into the reduced iron, it begins to melt in the hotter zones of the blast furnace. 1600 °C. Introduction The recent development of blast furnace manufacturing process forwards to minimize frequently refractories repairing and reduce the time of installation. Crude steel production begins with the reduction process, where the iron ore reacts with carbon sources inside the blast furnace. are also contained in small quantities in the pig iron. The heat required for this is provided by the (exothermic) combustion of the coke. Blast furnace gases contain close to 30% CO 2, after full combustion of the CO fraction, while the overall flue gas stream from an integrated steel mill is ∼15% CO 2.The same CO 2 capture options introduced above for power-generation plant can therefore also be applied to a steel mill:. In which “solidification form” is pig iron mostly tapped. In contrast, graphite is a thermodynamically stable compound that has survived even with long annealing times. How does a liquid-in-glass thermometer work? Pellets are produced from this lower iron content ore. FeO &~+~ C &&\rightarrow~ Fe &&+ ~CO ~~~~~~ \text{(wüstite} \rightarrow \text{iron)} \\[5px] Process Control. An unfavourable accumulation of ores at the contact points can also make gas flow difficult and thus leave non-reduced iron ore behind. The refractory lining's properties are enhanced through cooling to protect the refractory lining from excess heat. To create Steel with the Blast Furnace, input a source of Iron, such as Iron Ingots, Iron Ore, or Iron Dust, and also 6 Compressed Air Cells. Stopping the blast furnace and lowering the burden Opening of both doors (for the introduction of the robot) and probe holes located in the top (for fixing of the robot) Gunning of the insulating plug Assembly of the Giro Gun robot All the works have been done on a tight schedule within 48 hours. New linings and manual repairs: dense shotcrete products (REFRAJETCRETE ® LC), self-flowing backfilling compounds (REFRASELFCAST ®) Hot repairs with a gunning robot: gunning (REFRAJET ®), cement-free shotcreting (REFRAJETCRETE ® Nanobond) Start-up protection (manual … This is the reason why pig iron has a relatively high carbon content. 4. trough geometry and cooling system. These are the goals of BEKA! In Duisburg thyssenkrupp is testing the “sequence impulse process with induced shockwaves”, a new blast furnace technology designed to enhance process efficiency. One of the aims is to help reduce CO2 emissions – both at the company’s own plant and around the world by marketing the technology globally. During the operation, the bleeders at the top of the blast furnace are also opened to pull some of the blast furnace gas … The equilibrium then shifts in the direction of the condensation process (this effect can also be seen very clearly on cooled beverage cans, where the water contained in the air condenses and water pearls form). The enrichment of solid iron with carbon in a temperature range between 900 °C and 1200 °C is also referred to as carburisation. Required fields are marked *. \label{direkt} Metallurgy of the Blast Furnace. The overall balance thus remains exothermic. heat is released – as is usual in a combustion process. & C + O_2  \rightarrow CO_2 ~~~ \text{(exotherm)} \\[5px] This in turn is favoured by relatively high manganese concentrations and faster cooling rates. Blast furnace produces pig iron from iron ore by reducing action of a carbon at a high temperature in the presence of fluxing agent such as limestone. Deaerator working principle, Types and Process Control, Types of Check Valves (Non Return Valve) NRV, Control Valve working, Components & Types, Distributed Control Systems (DCS) Information. This requires an element that binds oxygen more strongly than iron. Nevertheless, the temperature in this indirect reduction zone of 400 °C to a maximum of 800 °C is too low to melt the reduced iron! It is usually cast in small ingots and offered to foundries for melting down with other materials (charging). The heat required for this must also be generated by burning of coke. at the wet-gunning refractories. All these reactions are endothermic. In this region, the so-called indirect reduction of iron ores to iron by carbon monoxide takes place. The indirect reduction can be divided into several intermediate reactions, whereby the iron content in the ores continuously increases and ultimately pure iron is produced. 3. The blast furnace module is part of the steel manufacturing course. The absorbed carbon remains dissolved in the molten iron. The blast furnace (BF) ironmaking process is currently the dominant process for providing steelmaking raw materials worldwide. When the liquid pig iron solidifies, the silicon content in particular determines whether the dissolved carbon precipitates in its pure form as graphite ($$C$$) in the microstructure or as iron carbide ($$Fe_3C$$, cementite). While the liquid water can evaporate briefly at a local point due to statistical fluctuations (“reaction”), water is again condensed locally from the supersaturated air at another point (“reverse reaction”). At low temperatures, carbon monoxide mainly decomposes to carbon dioxide and carbon! \end{align}. Fundamental equation of planetary gears (Willis equation). Due to the graphite in the stable solidified microstructure, the fracture surface of the pig iron appears matt-grey. By absorbing the carbon, the solidification point of the iron is reduced from 1536 °C to approx. These processes are described in more detail in the following articles. Only the last chemical reaction of wüstite to iron is exothermic and supplies heat. Blast furnaces reduce iron ore through a process combining coke and limestone. Your email address will not be published. The Blast Furnace is a members-only minigame situated in Keldagrim for smelting bars.The furnace here only requires half as much coal when smelting usually, so it can be useful when smelting the ores that require more coal..