Steel Fabrication: 3 Desulfurization Methods To Consider

Posted on: 9 March 2016

When steel is being fabricated, sulfur may bind to the steel. Generally speaking, sulfur is not a desirable alloy that is added with steel, and it is considered to be an impurity instead. This is because sulfur causes brittleness and reduces weldability of steel if it exceeds 0.05%. As a result, desulfurization is an important step in many steel fabrication processes. This article will look at 3 common desulfurization methods.

Adding Magnesium Reagent to Hot Steel

One of the most common and popular desulfurization methods commonly recommended for producing high quality steel is to add magnesium reagent to hot liquid steel. The magnesium reagents can be injected into the ladle of the sulfur in either granular or powder form in order to produce steel with the lowest sulfur content. The sulfur in the steel will bind to the magnesium instead. The sulfur and the magnesium will both become gases and can be easily removed from the liquid steel.

This desulfurization method is highly recommended because it is highly effective and because it can remove sulfur from the steel quickly. This method is also quite simple to execute and does not require many steps.

Attempting Deep Desulfurization with Slags

In the event that manganese is not available, another highly recommended method for desulfurizing steel involves forming a slag over the molten metal. To use this method, the amount of oxygen available must be minimal while there must be high concentrations of slag available. Slag is basically stony waste matter that is separated from metals during the fabrication process.

While this method is also quite effective, it causes high refractory wear on the steelmaking furnace due to the high temperatures needed for this method to work. This method also requires multiple steps and is a bit more complicated in comparison to simply adding a magnesium reagent. In addition, the elements and gases that are present in the slag must be within a certain range for the sulfur to be removed effectively from the steel. Although this method is a bit troublesome, it can be used to subsequently remove other unwanted alloys from the steel in order to improve its purity.

Injecting Active Agents, Particularly Calcium

Using active agents that are also basic ingredients in iron and steel working is also commonly recommended for desulfurization because these active ingredients should be readily available and easily accessible. In particular, calcium is commonly used for desulfurization, as calcium will not only remove the sulfur but will also improve the fluidity, machinability, ductility and strength of the steel.

Active agents, like calcium, can be injected in conjunction with other desulfurization methods, such as when slag is being formed or when the magnesium reagent is being added. This further enhances the overall effectiveness of this method. Calcium as an active agent can also greatly improve the properties of steel in many aspects. While it can be effective and can improve the properties of the steel, special equipment is needed for this method as the addition of active agents like calcium will result in a violent agitation and reaction. The amount and concentration of the active agent that is to be injected needs to be carefully calculated.


Desulfurization is a particularly important process during steel fabrication. If the sulfur is not effectively removed from the steel, it will compromise the steel's strength, integrity and other properties. Familiarizing with desulfurization techniques can help metalworkers determine which application or method may be most suitable based on the final steel requirements, properties and characters that are needed. Keep in mind that the technical expertise required for each method is also different, and some methods require more professional assistance than others. For more information, contact a steel fabricator from a company like Simko Industrial Fabricators.