The Siemens Martin Steel Production Method

In our materials science section, we’ve dedicated this article to the Siemens Martin Steel Production Method, one of the steel production methods. In this article, we’ll cover the advantages and disadvantages of the Siemens Martin method, its operating system, and the characteristics of Siemens Martin furnaces.

The Siemens Martin Steel Production Method

This method aims to use scrap steel together with molten pig iron at the same time, allowing scrap material to be brought back into production and producing alloyed steel. The heated air temperature is raised to as much as 2000°C. The furnace is charged with a 1/3 ratio of scrap and limestone and heated for 3 hours. Then molten pig iron is added to the furnace. During production, samples are taken from the melt and analyzed. This is how high-quality steel is produced.

It takes its name from Pierre Émile Martin, who discovered this method in 1864, and William Siemens, who later improved this steel production method. It’s an old method that hasn’t lost its value among steel production methods. However, for several reasons, its use has declined today.

The Working Principle of the Siemens Martin Steel Production Method

This method uses an open-hearth furnace consisting of a hearth resembling a bathtub. High temperatures need to be reached in Siemens-Martin furnaces. To achieve this, the air that supplies combustion needs to be preheated.

Working principle of the siemens martin steel production method (above)

Preheating is done by passing the air through a brick heat exchange system that has been heated by the gases heading to the flue. To prevent the preheating system from cooling down, the direction of this airflow is switched every 15 minutes. The preheating system is located in the lower part of the furnace. The preheated air meets liquid or gaseous fuels at the burner ports. This mixture ignites the furnace. The resulting flame heats the charge materials and the bricks inside the furnace

Advantages of the Siemens Martin Steel Production Method

One advantage of the Siemens Martin steel production method is that it makes it possible to produce steel by melting scrap in addition to pig iron. The steel produced here is also in a flowing liquid state, as it is with converters. The roofs of Siemens Martin furnaces are made from silica bricks. This makes it possible to reach temperatures of 1600-1700°C in the furnace. Coal, lignite, generator gas, and various petroleum products are used for heating in Siemens Martin furnaces.

If low-calorific gases are to be used in this type of furnace, the gas needs to be preheated. After the scrap material, limestone is added to the furnace, followed by molten pig iron. If coke or fuel oil is used, the furnace doesn’t need preheating. Siemens Martin furnaces run for 5 to 15 hours per cycle, and these furnaces are serviced every 10 months.

Scrap material, limestone, and molten iron are used for steel production in Siemens-Martin furnaces.

As melting takes place, the foreign substances in the mixture inside the furnace become slag. This slag contains all the foreign substances that are harmful to the steel. Slag collection pools are located inside the furnace to prevent the slag from damaging the preheating system via the airflow inside the furnace.

In the Siemens Martin steel production method, the dimensions of a typical furnace with a 250-ton capacity are as follows. Length 15 m, width 6 m, and capable of holding liquid steel at a depth of 1 meter. The capacity of these hearths is generally around 100-375 tons per heat cycle. Each cycle takes 8-10 hours.

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