Cryogenic Treatment Equipment: Knowledge in the Steel Industry 

Cryogenic Treatment Equipment: Knowledge in the Steel Industry

Xinfengli Technology Co., Ltd. is a domestic brand specializing in the research, development, and sales of ultra-low temperature cryogenic equipment and various liquid nitrogen cryogenic treatment devices in China. Its primary products include the XFL series liquid nitrogen cryogenic chambers, XFL series liquid nitrogen low-temperature units, XFL series cryogenic treatment equipment, XFL series high-low temperature test chambers, XFL series mold cryogenic treatment systems, XFL liquid nitrogen ultra-low temperature processing technologies, XFL liquid nitrogen ultra-low temperature treatment skills, and XFL liquid nitrogen ultra-low temperature deep processing machinery. With years of experience in liquid nitrogen low-temperature equipment and liquid nitrogen quick-freezing food machinery, Xinfengli offers comprehensive products and services. Its cryogenic treatment technology has emerged as a novel process for enhancing the performance of metal workpieces in recent years.

Market Analysis of the Steel Industry

To understand the steel industry, one must grasp not only fundamental metallurgical techniques but also industry fundamentals and the interconnections across various sectors of the economy. This learning process can be tedious and monotonous. To help newcomers to the industry grasp it more easily and comprehensively, I will employ simple, engaging language and everyday analogies, adopting a question-and-answer format to elucidate common and universally relevant issues. It's important to note that these explanations aim to provide a general understanding of the topics. Some points may not be rigorously accurate, and corrections are warmly welcomed.

1. Blast Furnace: A Cauldron Without Fire

Q: What is a blast furnace?
A: A blast furnace is essentially a large cauldron.

To the uninitiated, a steelmaking blast furnace may seem enigmatic, but in essence, it is just a large cauldron—one that "cooks" (refines steel) without fire.

Q: How does it "cook" without fire?
A: With gas—oxygen, to be precise. Oxygen aids in heating the "ingredients" (molten iron).

During steelmaking, the cauldron is tilted, and molten iron at 1300°C, glowing red-hot, is poured into it. The cauldron is then righted, and oxygen is introduced. Elements such as carbon and silicon in the molten iron undergo oxidation, releasing heat and elevating the temperature further. If the temperature becomes excessively high, oxygen flow is reduced or temporarily halted, or scrap steel is added to lower the temperature. Once the carbon content in the molten iron is sufficiently reduced, the "meal" is ready. The molten steel is then poured into a basin (ladle), where "seasonings" (alloys) are added beforehand—not salt or MSG, but the necessary alloys to produce various steel grades with distinct properties.

This basin of molten steel, along with the steel itself, is transported to the continuous casting workshop. For subsequent processes, this molten steel resembles kneaded dough, ready to be shaped into various products such as twisted dough (rebar), fritters (coiled and wire rods), pizzas (medium and heavy plates), and noodles (hot-rolled strips).

2. What Are Sinter and Pellets in Ironmaking Burden?

In ironmaking, "raw materials" refer to lump ore, while "processed materials" denote sinter and pellets. The distinction lies in their processing: sinter and pellets undergo heating and combustion, incorporating auxiliary materials like coke, iron oxide scale, and furnace dust, effectively being "cooked." Lump ore, in contrast, is naturally occurring high-grade ore in its raw state, untouched by fire—hence "raw." For ironmaking, achieving the same iron output requires more coke when using lump ore, making it more costly.

3. Why Use Sinter, Pellets, and Lump Ore Instead of Fine Ore in Ironmaking?

The blast furnace resembles a stove used for heating and cooking in northern China during winter. However, while coal is the fuel in stoves, ore in blast furnaces participates in combustion. Typically, stoves burn coal briquettes or honeycomb briquettes, not loose coal fines. Pouring coal fines directly into a stove would extinguish the fire, as the fine particles lack interstitial spaces, impeding airflow. Similarly, to ensure proper combustion and furnace conditions in blast furnaces, ore fines are agglomerated with water, coke fines, and other materials into pellets or sintered lumps before being charged into the furnace, ensuring adequate permeability for normal combustion. Lump ore can also be used for the same purpose.