Steel may be silent, but it builds our world. From the skeletal framework supporting skyscrapers
to the tracks of speeding trains, from the protective shells of automobiles to the pots and pans we
use daily—the pulse of steel beats in every corner of life. At the core of this vast steel lifeline lies a
piece of equipment that, though unseen by the public, beats like a heart, continuously pumping
the lifeblood of industrial civilization—the converter.
Stepping into a modern converter steel-making workshop, the deafening roar overwhelms the senses
before the visual impact. Scorching air currents carry energy, as if one were inside some gigantic living
organism. The most striking feature is the massive vessel capable of holding hundreds of tons of molten
iron. It lies quietly tilted, awaiting its next mission. This is not merely a container; it is the core hub of
the modern steel industry’s efficient operations.
Step 1: The Surge of Molten Iron
The scalding molten iron rushes from the blast furnace, pouring into the converter's massive furnace like
molten lava. The temperature inside the furnace instantly approaches 1,600°C, causing the air to warp and
distort in the heat. At this point, the operators act like seasoned conductors, precisely calculating and
adding specific amounts of flux agents (such as quicklime) and coolants (such as scrap steel) based
on the composition and temperature of the molten iron. The furnace opening is then tightly sealed,
marking the beginning of a vigorous metallurgical reaction.
Step 2: The Powerful Blowing of Oxygen
The core “magic” of the converter furnace is activated—a powerful oxygen stream is violently blown
into the depths of the molten pool at supersonic speed from the nozzles at the top of the furnace! The
molten iron boils and churns violently, resembling a pool of awakened lava. Excessive elements such as
carbon, silicon, manganese, and phosphorus in the molten iron undergo intense oxidation reactions with
oxygen under high-pressure oxygen. This process not only significantly increases the temperature of the
molten pool (up to over 1,700°C) but also converts these unwanted elements into slag or gases for
removal. The blowing process, lasting approximately 15–20 minutes, is a critical stage in converter
steelmaking. Operators closely monitor real-time changes in the steel composition through indicators
such as flame color, sound, and gases escaping from the furnace opening, akin to controlling a
manageable metallic storm.
Step 3: Precise Endpoint Control
When the molten steel composition approaches the target requirements, the blowing process abruptly
stops. The converter begins to tilt slowly, and operators quickly extract steel samples for rapid analysis.
Using advanced equipment such as spectrometers, precise measurements of key elements like carbon,
phosphorus, and sulfur in the molten steel can be obtained within minutes. Based on these data, final
composition adjustments are made—deoxidizers (such as silicon iron or aluminum) are added to remove
residual oxygen from the molten steel, and alloying elements (such as manganese iron or chromium iron)
are added as needed to impart the desired properties to the molten steel. The entire process is precise
and efficient, representing the perfect mastery of steel composition through technology.
Step 4: The Birth of Molten Steel
Qualified molten steel is poured into a large molten steel ladle, marking the successful completion of a
converter steelmaking cycle. The molten steel, glowing with the light of hope, is then transported to the
continuous casting machine, beginning its transformation into various steel products. The converter quickly
cleans the residual slag from the furnace opening, preparing to receive the next batch of molten iron. The
smelting cycle of modern large converters is typically controlled within 40 minutes, a level of efficiency
that is truly remarkable.
Converter steelmaking, particularly the “oxygen top-blown converter steelmaking method,” boasts core
advantages in terms of efficiency and cost control:
Rapid and efficient: Short single-furnace smelting cycle (typically 20–40 minutes) and massive single-furnace
output (up to hundreds of tons), serving as the cornerstone of large-scale steel production.
Cost-effective: Primarily relies on the chemical energy of molten iron for heating, eliminating the need for
additional fuel; relatively simplified equipment results in significantly lower investment and operational costs
compared to other steelmaking methods.
Quality control: High levels of automation and intelligence ensure precise process control, resulting in excellent
purity and compositional stability of molten steel.
Green evolution: Modern converters are equipped with powerful gas recovery (LDG) and waste heat utilization
systems, which recover and purify the carbon monoxide-rich gas generated during smelting as a valuable energy
source, significantly reducing energy consumption and emissions.
From the first roar of the Bessemer converter in 1856, to the revolutionary breakthrough of oxygen top-blowing
technology in the mid-20th century, to today's ongoing advancements in intelligence, scale, and environmental
sustainability, converter steelmaking technology has embarked on a path of continuous self-innovation. It is not
only the undisputed mainstay of the modern steel industry (approximately 70% of the world's crude steel is
produced by converters), but also a key indicator of a country's steel industry modernization level.
The next time you touch the cold steel railing or gaze at the steel forest of the city skyline, remember: behind all
this lies the relentless, fiery molten pool within those massive converters. Under precise control, they efficiently
transform molten iron into the cornerstone of modern civilization. The converter, this invisible giant “furnace,”
silently yet powerfully drives the steel torrent, continuously shaping our strong and vibrant world. It is the deep
pulse of industrial power, one of humanity's most magnificent mastery of metallic elements.