Abstract
Iron Losses from Desulfurization Purge Slag
In modern metalworking processes, desulfurization is one of the most important metal processing techniques, used to reduce sulfur levels in metals. During desulfurization, a special flux is poured over the metal and allowed to burn. The burning flux produces a metal slag which must be separated from the metal prior to purification and further processing. Iron losses during this process occur due to the presence of residual sulfur in the metal which reacts with the flux producing non-metallic oxides and causing a reaction between the flux and the metal surface. This paper reviews some of the causes of iron losses during desulfurization and provides a summary of potential methods to reduce them.
Introduction
Desulfurization is a common metal processing technique used to reduce the sulfur content of metals. The sulfur reduction processes include liquid metal fluxing, ladle refractory lining, and desulfurization slagging. In this technique, a slag-forming flux containing calcium-based compounds, calcium oxide and calcium hydroxide is poured over a metal surface and allowed to burn. This burning produces a metal slag which must be separated from the metal prior to purification and further processing.
During the desulfurization process, iron losses often occur due to the reaction between the acetylene and the oxygen in the air. The reaction between these elements forms iron oxide, which is non-metallic in nature and adheres to the metal surface. This reduces the available iron content and can cause problems during the purification process. In addition, the reaction of residual sulfur in the metal with the flux can also result in iron losses. The presence of sulfur in the metal makes it more difficult to separate the slag from the metal and can also lead to an increase in the amount of iron oxides contaminated with the metal during separation.
It is important to understand the causes of iron losses during desulfurization processes in order to reduce them and ensure the final product meets the desired specifications. This paper will review some of the main causes of iron losses during desulfurization, and provide a summary of potential methods that can be used to reduce them.
Factors Affecting Iron Losses
The main factors that can contribute to iron losses during desulfurization processes include the following:
Residual sulfur content of the metal
The presence of residual sulfur in a metal can lead to a reaction between the flux and metal surface. This reaction produces non-metallic oxides which are difficult to separate from the metal, reducing the useful iron content and leading to increased iron losses.
Reaction between the flux and oxygen in the air
The reaction between the flux and oxygen, specifically the oxygen in the air, produces iron oxide which is non-metallic, and adheres to the metal surface. This reduces the available iron content and can cause problems during the purification process.
Reaction between the flux and the metal surface
The reaction between the flux and the metal surface also results in iron losses, as the flux can penetrate the metal and form oxides or other compounds that can contaminate the metal during separation.
Chemical composition of the flux
The chemical composition of the flux used in the desulfurization process can also contribute to iron losses. Different flux compositions can create different reactions with the metal surface, resulting in the formation of compounds that can contaminate the metal and reduce its available iron content.
Temperature of the process
The temperature at which the desulfurization process takes place can also affect the rate at which iron losses occur. If the process is carried out at higher temperatures, the rate of oxidation increases, leading to higher iron losses over time.
Methods for Reducing Iron Losses
There are a number of methods that can be used to reduce the amount of iron losses during desulfurization processes. These include:
A. Pre-treatment of the metal surface before desulfurization: Pre-treating the metal surface with a coating or other protective layer before desulfurization can reduce iron losses due to oxidation reactions, as these reactions will occur on the surface of the coating or other protective layer instead of the metal surface.
B. Careful flux selection: Care should be taken when selecting the flux to be used in desulfurization processes. Different flux compositions can produce different reactions with the metal surface, and choosing a flux that does not react significantly with the metal surface can help reduce iron losses.
C. Maintaining strict temperature control: Careful control of the temperature at which desulfurization processes are carried out can help reduce the rate at which iron losses occur. It is important to keep the temperature of the process as low as possible without compromising the efficiency of the process.
D. Slag removal: Ensuring that all slag is removed from the surface of the metal after the desulfurization process can help reduce iron losses, as residual slag can contain iron oxides or other compounds that can contaminate the metal during separation.
Conclusion
Iron losses during desulfurization processes can be significant and can cause problems in the purification and further processing of metals. This paper has reviewed some of the main causes of iron losses during desulfurization and potential methods for reducing them. Reducing iron losses is important to ensure the final product meets the desired specifications, and by carefully controlling the parameters of the desulfurization process, it is possible to reduce iron losses and ensure high-quality products.
