Steel processed in BOF and electric arc furnaces is processed to obtain the required chemical composition and temperatures suitable for casting. For this purpose, different processes are used, resulting in different types of slag. Among the slags produced, the so-called white slag obtained by the LF process is the most common, although other processes such as vacuum degassing, argon-oxygen decarburization and vacuum oxygen decarburization may also be included (Euroslag, 2019). SECS typically have high CaO content and low oxidation levels. Some of these slags can be chemically ground, creating a powder that can be used as fertilizer. Coarse-grained SECS are typically recycled in other metallurgical processes (Euroslag, 2019). Lip shaft pans can also use hydraulic valves to tilt the pan. The largest pockets are not toothed and are usually cast with a special two-winch crane, with the main winch carrying the pocket while the second winch engages a pod at the bottom of the pocket. Lifting the second winch, the pan then turns on its cones. Pockets can be opened or covered. Covered pans have a domed (sometimes removable) lid to retain radiant heat; They lose heat more slowly than open pans. Small pockets usually do not have a lid, although a ceramic ceiling can be used instead (if available). In the past, degassing was studied and carried out in fixed volumes, for example in furnaces, ladles and crucibles.
It is also a typical setting for laboratory experiments. Degassing a steady-state volume by short ultrasonic sessions with empty intervals between them proves to be a good option. Figure 20.6 illustrates this by ultrasonic degassing of a 2 kg charge of an A380 alloy during 2-minute sessions. It is evident that each of the degassing sessions resulted in a further decrease in hydrogen concentration, while idle times allowed the release of gas from the bubble flotation fusion. Table 20.2 shows how this approach works for larger volume fades (Eskin, 1998). Medium and large pans suspended from a crane have a support that holds the pan on trees called tenons. To tilt the pocket, a gearbox is used, which is usually a worm gear. The transmission mechanism can be operated manually with a large wheel or can be operated by an electric or pneumatic motor. The driven rotation allows the operator to move the pocket operator at a safe distance and control the rotation of the pocket via a pendulum or radio remote control.
The driven rotation also allows the ladle to have a range of speeds that can be beneficial for the entire casting process. Of course, the driven rotation also reduces the effort required by the pocket operator and allows large quantities of molten metal to be transported and poured over long periods of time without operator fatigue. If the pocket is equipped with a manually operated gearbox, the most commonly used type of gearbox is the worm and wheel design, as it can be considered “self-locking” in most practical circumstances and with proper maintenance and does not require an internal friction brake to regulate the tilting speed of the pocket. Other types of gearboxes can also be used, but they must be equipped with an additional braking system that can hold the plate when the operator removes his hand from the steering wheel. Steel: electric arc furnaces, ladles, reheating furnaces and electric dipping pits Separation of the refining function of P and S from BOF/EAF into HMPT and LF, making BOF/EAF more or less a decarburization furnace. When HMPT covers the dephosphorization and desulphurization of pig iron, the Si in pig iron shall be kept to a minimum. This minimizes lime addition and thus slag development, excavation and iron loss, and maximizes the Mn reduction of Mn ore in the FRO, as explained in the previous section. The need to process large quantities of molten on an industrial scale, especially in large foundries and continuous foundries, shows a limit for batch degassing. A different approach must be used, and hot flow treatment seems to be a logical and viable possibility. For large melting/casting operations, it is more appropriate to move the cleaning gases and oxide inclusions from the melting and oxide inclusions from the melting or holding furnace to the metal transfer zone somewhere in the way from the furnace to the mold. One example of outgassing in the melt stream is a combination with vacuum outgassing, as shown in Figure 20.8a. A proposal to combine ultrasonic outgassing with argon drilling in a vessel through which cast iron constantly flows has recently been made (Han et al., 2010).
The steel production process under consideration consists of two electric arc furnaces (EAF), two argon-oxygen decarburization plants (AOD), two ladle furnaces (LF) and two continuous castings (DC), see diagram RTN corresponding to Figure 2. The following features of the problem are taken into account: The most common of these other shapes is called a drum trowel and has the shape of a horizontal cylinder suspended between two bogies. Large designs, often with capacities of more than 100 tons (98 long tons; 110 short tons), used in steel mills, are often referred to as vaspillières. [ref. needed] Torpedo basins are often used to transport molten iron from one blast furnace to another part of the steel mill. Some versions are even suitable for transport on special bogies that can be transported by road or rail. In metallurgy, a ladle is a container used to transport and pour molten metals. Pans are commonly used in foundries, ranging from small portable containers that look like a kitchen trowel and can hold 20 kilograms (44 lbs) to large steel mill pans that can hold up to 300 tons (295 long tons; 331 short tons).
Many non-ferrous metal foundries also use ceramic crucibles for transporting and casting molten metal, also calling them ladles. Steel: electric arc and hearth furnaces, ladles, vacuum degassing, continuous casting, heating furnaces The basic term is often prefixed to define the actual purpose of the ladle. The design of the base tray can therefore contain many variations that improve the use of the pocket for certain tasks. For example: iron: blast furnaces and ovens, sewage induction furnaces. can be reached in a pocket oven (LF). It is a small electric arc furnace with an 8 to 25 megavolt ampere transformer, three electrodes for arc heating and the pan that serves as the oven casing – as shown in A in the figure. For better heat transfer, argon or electromagnetic agitation is used. Most. Unless the ladle is to be used with alloys at very low temperatures, the ladle is also equipped with a refractory coating. It is the refractory coating that prevents the steel container from being damaged when the ladle is used to transport metals at high melting temperatures, which, if the molten metal comes into direct contact with the ladle shell, would quickly melt through the shell. Refractory coating materials come in many forms and the right choice depends a lot on the working practices of each foundry. Traditionally, pans were coated with prefabricated refractory bricks, but refractory concretes have tended to replace them in many countries.
Pans and pans are often designed for special purposes such as adding alloys to molten metal. Pans may also have porous caps inserted into the base so that inert gases can be blown through the ladle to improve alloy or metal processing practices. Development of the high-speed and low-slag blowing process in the large format combined blowing BOF (Top O2 Blow + Bottom Ar Injection for agitring) with dynamic blowing control and subsequent direct cutting of the thread. The objective is to maximize productivity and metal yield and minimize the superoxidation of the steel and molten slag as well as the transfer of slag into the ladle. Figure 1.6.19. Process sketch including heating of steel by electrodes (LF) or chemically in ladles. For the transport of very large quantities of molten metal, as in steel mills, the ladle can be suspended from wheels, a custom-made ladle transport trolley or an overhead and inclined crane with a second suspension lifting device. Foundry ladles are usually evaluated based on their working capacity rather than their physical size.
Hand trowels are generally known as thigh trowels and are equipped with a long handle to keep the heat of the metal away from the person holding them. Their ability is limited to what a man can safely handle. Larger pockets are commonly referred to as gear crane pockets. Their capacity is usually determined by the panning function. Small handpans can also be crucibles equipped with conveying devices. However, in most foundries, the foundry ladle refers to a steel container to which a lifting bar is attached so that the ship can be supported by an overhead crane or monorail and is also equipped with a mechanical device to rotate the container, usually in the form of a gearbox. The gearbox can be operated manually or driven. (See the following paragraph for details). Ultrasonic degassing of aluminum has been used in foundries for precision investment, sand, gravity and low and high pressure casting.
Take the example of the sand flow. A special ultrasonic degassing system, UZD-200, was developed in 1959 for the outgassing of up to 250 kg of melt in a stable volume (figure 20.7). The installation (fixed and mobile) consisted of a 10 kW generator that powered four magnetostrictive transducers operating in sequence with a time interval of 15 to 20 seconds. The frequency was 19.5 kHz and the total sound power was 1.6 kW. The system was equipped with a time relay that allowed a programmed degassing plan. The shaft guidance system initially consisted of a steel extension and a titanium sonotrode. Later, titanium was replaced by a niobium alloy.