Ladle (foundry)
   HOME

TheInfoList



OR:

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 sc ...
, a ladle is a vessel used to transport and pour out molten metals. Ladles are often used in
foundries A foundry is a factory that produces metal castings. Metals are cast into shapes by melting them into a liquid, pouring the metal into a mold, and removing the mold material after the metal has solidified as it cools. The most common metals pr ...
and range in size from small hand carried vessels that resemble a kitchen ladle and hold to large steelmill ladles that hold up to . Many non-ferrous foundries also use ceramic
crucible A crucible is a ceramic or metal container in which metals or other substances may be melted or subjected to very high temperatures. While crucibles were historically usually made from clay, they can be made from any material that withstands te ...
s for transporting and pouring molten metal and will also refer to these as ladles.


Types

The basic term is often prefixed to define the actual purpose of the ladle. The basic ladle design can therefore include many variations that improve the usage of the ladle for specific tasks. For example: * Casting ladle: a ladle used to pour molten metal into moulds to produce the casting. * Transfer ladle: a ladle used to transfer a large amount of molten metal from one process to another. Typically a transfer ladle will be used to transfer molten metal from a primary melting furnace to either a holding furnace or an auto-pour unit. * Treatment ladle: a ladle used for a process to take place within the ladle to change some aspect of the molten metal. A typical example being to convert cast iron to ductile iron by the addition of various elements into the ladle. Unless the ladle is to be used with alloys that have very low temperature melting point, the ladle is also fitted with a refractory lining. It is the refractory lining that stops the steel vessel from suffering damage when the ladle is used to transport metals with high melting temperatures that, if the molten metal came in direct contact with the ladle shell, would rapidly melt through the shell. Refractory lining materials come in many forms and the right choice very much depends on each foundry's working practices. Traditionally ladles used to be lined using pre-cast firebricks however refractory concretes have tended to supersede these in many countries. Foundry ladles are normally rated by their working capacity rather than by their physical size. Hand-held ladles are typically known as ''handshank ladles'' and are fitted with a long handle to keep the heat of the metal away from the person holding it. Their capacity is limited to what a man can safely handle. Larger ladles are usually referred to as geared crane ladles. Their capacity is usually determined by the ladle function. Small hand-held ladles might also be crucibles that are fitted with carrying devices. However, in most foundries, the foundry ladle refers to a steel vessel that has a lifting bail fitted so that the vessel can be carried by an overhead crane or monorail system and is also fitted with a mechanical means for rotating the vessel, usually in the form of a gearbox. The gearbox can either be manually operated or powered operation. (See the paragraph below for further details). For the transportation of very large volumes of molten metal, such as in
steel mill A steel mill or steelworks is an industrial plant for the manufacture of steel. It may be an integrated steel works carrying out all steps of steelmaking from smelting iron ore to rolled product, but may also be a plant where steel semi-finish ...
s, the ladle can run on wheels, a purpose-built
ladle transfer car A ladle transfer car is a material handling tool which is used in foundries A foundry is a factory that produces metal castings. Metals are cast into shapes by melting them into a liquid, pouring the metal into a mold, and removing the mol ...
or be slung from an
overhead crane An overhead crane, commonly called a bridge crane, is a type of crane found in industrial environments. An overhead crane consists of two parallel rails seated on longitudinal I-beams attached to opposite steel columns by means of brackets. ...
and will be tilted using a second overhead lifting device. The most common shape for a ladle is a vertical cone, but other shapes are possible. Having a tapered cone as the shell adds strength and rigidity to the shell. Having the taper also helps when it comes time to remove the refractory lining. However straight sided shells are also fabricated as are other shapes. The most common of these other shapes is known as a drum ladle and is shaped as a horizontal cylinder suspended between two
bogie A bogie ( ) (in some senses called a truck in North American English) is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transp ...
s. Large versions, often having capacities in excess of are used in steel mills are often referred to as torpedo ladles.{{cn, date=August 2017 Torpedo ladles are commonly used to transport liquid
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
from a
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 "forced" or supplied above atmospheric ...
to another part of the steel mill. Some versions are even adapted so that they can be carried on special bogies that can be transported by either road or rail.


Pour designs

Ladles can be "lip pour" design, "teapot spout" design, "lip-axis design" or "bottom pour" design: *For lip pour design the ladle is tilted and the molten metal pours out of the ladle like water from a
pitcher In baseball, the pitcher is the player who throws ("pitches") the baseball from the pitcher's mound toward the catcher to begin each play, with the goal of retiring a batter, who attempts to either make contact with the pitched ball or draw ...
. *The teapot spout design, like a teapot, takes liquid from the base of the ladle and pours it out via a lip-pour spout. Any impurities in the molten metal will form on the top of the metal so by taking the metal from the base of the ladle, the impurities are not poured into the mould. The same idea is behind the bottom pour process. *Lip-axis ladles have the pivot point of the vessel as close to the tip of the pouring spout as can be practicable. Therefore as the ladle is rotated the actual pouring point has very little movement. Lip-axis pouring is often used on molten metal pouring systems where there is a need to automate the process as much as possible and the operator controls the pouring operation at a remote distance. *For bottom pour ladles, a stopper rod is inserted into a tapping hole in the bottom of the ladle. To pour metal the stopper is raised vertically to allow the metal to flow out the bottom of the ladle. To stop pouring the stopper rod is inserted back into the drain hole. Large ladles in the steelmaking industry may use slide gates below the taphole. Ladles can be either open-topped or covered. Covered ladles have a (sometimes removable) dome-shaped lid to contain
radiant heat Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. Thermal radiation is generated when heat from the movement of charges in the material (electrons and protons in common forms of matter) is ...
; they lose heat slower than open-topped ladles. Small ladles do not commonly have covers, although a ceramic blanket may be used instead (where available). Medium and large ladles which are suspended from a crane have a bail which holds the ladle on shafts, called
trunnion A trunnion (from Old French "''trognon''", trunk) is a cylindrical protrusion used as a mounting or pivoting point. First associated with cannons, they are an important military development. Alternatively, a trunnion is a shaft that positions a ...
s. To tilt the ladle a gearbox is used and this is typically a
worm gear A worm drive is a gear arrangement in which a worm (which is a gear in the form of a screw) meshes with a worm wheel (which is similar in appearance to a spur gear). The two elements are also called the worm screw and worm gear. The terminolo ...
. The gear mechanism may be hand operated with a large wheel or may be operated by an electric motor or pneumatic motor. Powered rotation allows the ladle operator to be moved to a safe distance and control the rotation of the ladle via a pendant or radio remote control. Powered rotation also allows the ladle to have a number of rotation speeds which may be beneficial to the overall casting process. Powered rotation obviously also reduces the effort required by the ladle operator and allows high volumes of molten metal to be transferred and poured for long periods without operator fatigue. Where the ladle is fitted with a manually operated gearbox, the type of gearbox most commonly used is the worm and wheel design because in most practical circumstances, and when correctly maintained it can be considered as "self-locking" and doesn't need an internal friction
brake A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction. Background ...
to regulate the tilting speed of the ladle. Other types of gear system can also be used but they have to be fitted with an additional braking system that can hold the ladle if the operator takes his hand off the hand-wheel. Lip-axis ladles may also use hydraulic rams to tilt the ladle. The largest ladles are un-geared and are typically poured using a special, two-winch crane, where the main winch carries the ladle while the second winch engages a lug at the bottom of the ladle. Raising the second winch then rotates the ladle on its trunnions. Ladles are often designed for special purposes such as adding
alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...
s to the molten metal. Ladles may also have porous plugs inserted into the base, so inert gases can be bubbled through the ladle to enhance alloying or metallic treatment practices.


See also

*
Crucible A crucible is a ceramic or metal container in which metals or other substances may be melted or subjected to very high temperatures. While crucibles were historically usually made from clay, they can be made from any material that withstands te ...
*
Ladle transfer car A ladle transfer car is a material handling tool which is used in foundries A foundry is a factory that produces metal castings. Metals are cast into shapes by melting them into a liquid, pouring the metal into a mold, and removing the mol ...


External links


About ladles
and
perlite Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently. It is an industrial m ...
used in a
foundry A foundry is a factory that produces metal castings. Metals are cast into shapes by melting them into a liquid, pouring the metal into a mold, and removing the mold material after the metal has solidified as it cools. The most common metals pr ...
Casting (manufacturing) Metallurgical processes Steelmaking