Steel, a cornerstone material in modern construction and manufacturing, undergoes various refining processes to meet specific quality and application requirements. Three prominent steelmaking methods —— Converter Steelmaking, Open Hearth Steelmaking, and Electric Arc Furnace (EAF) Steelmaking—have played pivotal roles in shaping the steel industry. In this article, we will introduce the first method of steelmaking —— converter steelmaking.
Major raw material
Converter steelmaking used widely in the globe, it utilizes molten steel, slag material including lime, quartz, fluorite and so on to produce. At the same time, some steel scrap, cold pig iron, ores and many others are necessary for converter steelmaking as a result of adjusting temperature.
Entire technique process
Entire technique process of converter steelmaking can be concluded into 6 steps: blast furnace molten steel, molten steel pretreatment…… , and all steps are shown in Figure 1 as below.
Fig. 1 Entire technique process of converter steelmaking
Process of converter steelmaking
Converter steelmaking, a kind of steelmaking method, depends on heat of chemical reaction between molten steel and its compositions to finish steelmaking process without any external fuel’s help, utilizes molten steel, steel scrap and so on as major raw materials to make this process.
Shape of converter is unique, if you see it at first time, you will think that its shape looks like a pear, it changed big gradually from top to bottom of converter. The converter is lined with refractory bricks to withstand high temperatures during steelmaking. Top of it has a small hole also called vent hole, it allows compressed gas through it and was blown to inside of converter. Moreover, liquid pig iron with 1300℃ approximately and a certain quantity of lime are injected into it. After the process that oxygen is blown to molten state pig iron, including impurities are oxidized promptly such as C, Si, Mn, etc. Meanwhile, it releases a large amount of heat to surroundings. Some of it can increase so high temperature with a small dosage, for example, 1% Si can make pig iron’s temperature increase about 200℃. Thus, temperature inside of furnace reaches enough high. This is the reason why this method do not use any other fuels that we mentioned above.
Then, Mn, Si and other impurities oxidized into slag, P also oxidized subsequently and generate ferrous phosphate. It will react with lime(CaO) to generate stable compounds, that is calcium phosphate and calcium sulphide and they became slag together. At this moment, it indicates steel was formed.
Fig. 2 Schematic map of top oxygen blowing converter
Classification
Converter has many classifications all over the world, it mainly have three standards to classify, they are as follows:
- Refractory materials:
It can be divided into acid and alkali types;
- Region that air blown to inside furnace:
This classification included top blown, bottom blown and side blown;
- Gas types:
Air converter and oxygen converter belong to this classification standard.
Among these types of converter that we mentioned above, it has two types used the most commonly and widely: alkali oxygen top blown converter and top and bottom combined blown converter. They are many advantages such as fast producing speed, high yield, low costs, less investment and so on, so that it used by many steel plants.
Conclusion
In the realm of converter steelmaking, the journey culminates in a crucial intersection of tradition and technological advancements. The converter, a pivotal apparatus in metallurgy, transforms raw materials into the resilient backbone of modern infrastructure: steel. This process encapsulates the industry’s evolution, from traditional methods to contemporary efficiency. The article’s exploration delves into the practical intricacies, unveiling how converter steelmaking not only meets the demands of today but lays the foundation for tomorrow’s structural landscape. The conclusion marks not just the end of a manufacturing process, but a testament to the enduring adaptability and significance of steel in shaping our industrial progress.
