What is Ladle (metallurgy)?

In metallurgy a ladle is a barrel or vessel used for transporting and pouring molten metal.Ladles are commonly used in foundries and range in size from small, hand-held containers resembling kitchen ladles and holding 20 kg (44 lb) to large ladles weighing up to 300 tons (295 long tons; 331 short tons).Many non-ferrous foundries also use ceramic crucibles for transporting and pouring molten metal, also known as ladles.

Types

Basic terms are often prefixed to define the actual use of the ladle.Therefore,the basic ladle design can include many variations that improve the use of the ladle for a particular task. For example:

Ladle: A ladle used to pour molten metal into molds to produce castings.

Transfer Ladle:A ladle used to transfer large quantities of molten metal from one process to another.Typically, transfer ladles are used to transfer molten metal from primary melting furnaces to holding furnaces or automatic pouring units.

Processing Ladle:A ladle in which processes that alter some aspect of the molten metal take place.A typical example is the conversion of cast iron to ductile iron by adding various elements in the ladle.Unless the ladle is used with alloys with very low melting points, the ladle is also fitted with a refractory lining.When ladles are used to transport metals with high melting temperatures, the refractory lining protects the steel vessel from damage, and if the molten metal comes into direct contact with the ladle shell, it will melt rapidly through the shell.Refractory lining materials come in many forms and the correct choice depends largely on the working practices of each foundry.Ladles have traditionally been lined with prefabricated refractory bricks, but in many countries refractory concrete tends to replace these linings.

Casting ladles are usually rated for their working capabilities rather than physical size.A hand-held ladle is often called a handle ladle and has a long handle to keep the heat of the metal away from the person holding it.Their abilities are limited to what a single person can safely handle.Larger ladles are often referred to as geared crane ladles.Their capacity is usually determined by the ladle function. Small hand-held ladles that may also be crucibles with carrying devices.In most foundries, however, a foundry ladle is a steel container fitted with lifting rings so that the container can be handled by an overhead crane or monorail system, and also fitted with a mechanism for rotating the container, usually in the form of a gearbox.The gearbox can be manually or power operated.For the transport of large quantities of molten metal, such as in steel mills, ladles can be run on wheels, dedicated ladle transfer vehicles or hoisted from an overhead crane and tilted using a second overhead lifting device.

The most common shape of the ladle is a vertical cone, but other shapes are possible.Having a tapered cone as the shell increases the strength and rigidity of the shell. Having a taper also helps when the refractory lining needs to be removed.However, straight-sided shells can also be manufactured like other shapes.The most common of these other shapes is the drum ladle, which is shaped as a horizontal cylinder suspended between two bogies.Steel mills typically use larger versions with capacities in excess of 100 tons (98 long tons; 110 short tons), often called torpedo ladles.Torpedo ladles are commonly used to transport molten iron from a blast furnace to another part of a steelworks.Some versions have even been modified to be carried on special bogies for transport by road or rail.