How Many Types of Ladle Are There?

A ladle is a crucial piece of equipment in the steelmaking process, used for holding, transporting, and pouring molten steel at high temperatures. It plays a vital role in the steelmaking process, not only receiving molten steel from converters or electric furnaces, but also frequently used for steel refining (e.g., LF furnaces, VD/VOD furnaces), alloy fine-tuning, temperature control, and preparation for final continuous casting.

I. What is a Ladle?

A ladles, also known as a molten steel ladles, casting ladles, or steel pot, is a container with a refractory lining and a robust steel outer shell. It typically consists of a steel shell (outer shell) + insulation layer + permanent layer + working layer (refractory bricks or castable refractory), and can withstand temperatures above 1600℃ for molten steel.

Its top is open to receive molten steel, and its bottom has a nozzle (sliding nozzle or stopper system) to control the outflow of molten steel. It is usually transported by crane or ladle car and can be stirred using devices such as argon blowing. Its capacity ranges from tens to hundreds of tons, and it is commonly found between converters, electric furnaces, and continuous casting machines in modern steel plants. 

II. Main Roles of the Ladle in Steelmaking

1. Holding & Transporting Molten Steel: After tapping from the steelmaking furnace (such as a converter or electric arc furnace), the molten steel is poured into the ladle and then transported to the refining station or continuous casting platform.

2. Steel Refining Vessel: In the ladle refining furnace (LF) and vacuum degassing unit (VD/VOD), the ladle serves as a reaction vessel for desulfurization, deoxidation, alloying, and temperature homogenization operations. This is known as "ladle refining" or "secondary metallurgy."

3. Removing Inclusions: Argon blowing from the top or bottom of the ladle agitates the steel, achieving uniform composition and allowing inclusions to float to the surface.

4. Buffering & Pouring Before Continuous Casting: The ladle pours molten steel into the tundish, which then distributes it to the crystallizer for continuous casting.

III. Main Types of Steel Ladles

Based on capacity, application, structure, and refining function, steel ladles can be classified as follows:

1. By Capacity

• Small: Capacity typically below 100 tons, used for special steel, small-batch production, or foundry workshops.

• Medium: Capacity between 100 and 200 tons, widely used.

• Large: Capacity above 200 tons, commonly used in modern large converters or electric furnaces, reaching 300 tons or even larger.

2. By Function

Ordinary Steel Ladle: Only possesses basic functions such as holding, transporting, and casting. Relatively simple structure.

Refining Steel Ladle:

• Argon-blown Molten Steel Ladles: Equipped with permeable bricks at the bottom or sides for blowing inert gas (usually argon) for stirring.

• Vacuum-treated Steel Ladle:

1. VD Molten Steel Ladles: Equipped with a vacuum cover for vacuum degassing.

2. RH Steel Ladle: Requires use with the riser and downcomer of an RH vacuum circulation degassing device; molten steel is circulated within the vacuum chamber.

3. LF Ladle: Also known as a ladle refining furnace, it is equipped with an electric arc heating cover, electrodes, and an alloy feeding system. It can perform long-term heating, refining, and heat preservation, offering the most comprehensive functionality.

Rotating Axisymmetric Ladle: Used for certain special processes, such as RH refining.

Teapot-Shaped Ladle: Features a slag-blocking weir at the spout, resembling a teapot, effectively preventing slag from flowing out with the molten steel. Commonly used for steel grades requiring high cleanliness.

3. Classification by Tapping Method

Top Tapping: Molten steel is poured in from the top, commonly found in electric arc furnaces.

Bottom Tapping: Steel is tapped from the bottom via a sliding nozzle or stopper rod, facilitating flow control and reducing secondary oxidation. Widely used in modern continuous casting systems.

4. Classification by Refractory Material Structure

• Brick Ladle: The lining is constructed of refractory bricks, making maintenance and replacement more complex.

• Monolithic Cast Ladle: The lining is integrally cast using refractory castable, offering fast construction and long service life; currently the mainstream trend.

5. Classification by Cover Type

• Open Ladle: Without a cover, allows for rapid heat dissipation, suitable for short processes.

• Covered Ladle: Equipped with an insulated cover, reduces temperature drop and heat loss, improves energy efficiency, and is commonly used in long processes or for applications requiring insulated transport.

In modern steel production, especially for high-quality steel, the ladle has evolved from a simple "bucket" into a multifunctional, high-performance metallurgical reactor. Argon-blown ladles, LF ladles, and VD/RH vacuum-treated ladles are core equipment in modern steel mills. The specific type and structure chosen depends on the plant's steelmaking furnace process route, product portfolio, and production scale.

In short, the ladle is the link between "steelmaking" and "steel casting," the stage for the "final refining" of molten steel, and has a crucial impact on the quality, cost, and production efficiency of the final steel product.