In the grand landscape of modern iron and steel smelting, the blast furnace serves as the core heart, while the blast-furnace gun ranks among the critical equipment that safeguards the stable operation of this "heart". Hailed as the "Patron Saint" of the tapping area in the smelting industry, its core mission is to rapidly, accurately and safely seal the iron taphole gushing with molten iron after the blast furnace tapping operation, thereby providing a solid guarantee for the continuous, stable and safe production of the blast furnace.
The blast-furnace clay gun is not merely a simple mechanical device, but also an important supporting component for the high-pressure operation process of blast furnaces.
1.Core Process Functions
The primary process task of the blast-furnace clay gun is to seal the iron taphole. During the blast furnace smelting process, molten iron and slag are periodically discharged from the taphole of the hearth. Upon completion of tapping, the taphole must be tightly sealed immediately with refractory material (namely "gun clay") to withstand the blast furnace gas pressure inside the furnace, which can reach several kilograms or even higher. This prevents gas leakage or molten iron splashing, ensuring that the blast furnace can continue the next smelting cycle in a sealed state.
2.Lining Repair and Maintenance
This is a frequently overlooked yet crucial process function. During the clay-injecting operation of modern blast-furnace clay guns, the equipment not only fills the taphole channel that has been enlarged by the scouring of molten iron, but also extrudes a portion of the gun clay into the hearth interior. Under the combined effect of high pressure and high temperature inside the furnace, this part of the gun clay adheres to and solidifies on the inner wall of the hearth, forming a new protective layer (shaped like a mushroom). In this way, it repairs the damaged furnace lining and extends the service life of the blast furnace.
3.Adaptation to the Trends of High Pressure and Large Scale
With the development of blast furnaces towards larger scale, higher pressure and longer service life, the internal pressure of the furnace is continuously increasing, which imposes extremely high requirements on the sealing tightness and the density of gun clay. This necessitates that the clay gun must be equipped with enormous clay-injecting thrust and stable compaction force, so as to ensure that the gun clay can overcome the high pressure inside the furnace to enter smoothly and adhere tightly to the furnace lining.
From the equipment perspective, the blast-furnace clay gun is a sophisticated integrated system combining mechanics, hydraulics and electrical control. It has evolved from steam-driven and electric-driven models to the modern full-hydraulic-driven type. Currently, hydraulic clay guns have become standard equipment for modern large-scale blast furnaces, thanks to their advantages including high thrust, compact structure, smooth operation and easy implementation of remote automated control.
1.Equipment Structure and Components
A complete hydraulic clay gun for blast furnaces is mainly composed of the following core mechanisms:
Barrel (Clay Injection Mechanism): This is the "heart" of the clay gun. It consists of a clay cylinder and a clay pushing mechanism. The clay cylinder is used for storing and ejecting gun clay; it is usually made of high-strength chromium-molybdenum steel and undergoes glow ion nitriding treatment to enhance wear resistance and high-temperature resistance. The clay pushing mechanism (clay injection cylinder) provides powerful thrust to extrude gun clay out of the clay cylinder.
Slewing Mechanism: This is the "arm" of the clay gun. It is composed of a slewing cylinder, a slewing arm, a base, etc. Its function is to smoothly move the barrel from the safe position on the side of the iron runner to the position directly in front of the iron taphole, and retract it after the taphole sealing is completed. Modern clay guns mostly adopt a low-profile design; in the non-operating state, the entire barrel is positioned below the tuyere platform without affecting the traffic and structural integrity of the platform.
Pressing and Locking Mechanism: This is the "gripper" of the clay gun. After the gun nozzle is aligned with the iron taphole, this mechanism uses the enormous force generated by the hydraulic system to firmly press the nozzle against the clay sleeve of the taphole, withstanding the huge counter-thrust during clay injection and preventing clay leakage or equipment retraction.
Hydraulic and Electric Control System: This is the "nervous system" of the clay gun. The hydraulic station supplies power and controls the action sequence, speed and pressure of the cylinders through complex valve groups. The electric control system realizes functions such as remote operation, status monitoring and safety interlocking, ensuring that operators can control the equipment in a safe room away from high-temperature hazardous areas.
2.Key Technical Requirements
To meet stringent process requirements, the design of blast furnace clay guns must comply with the following standards:
Sufficient Thrust and Pressure: The clay injection thrust generally needs to reach hundreds or even thousands of kilonewtons (kN), and the clay pressure at the nozzle outlet should reach (30–40)×10⁵ Pa, so as to overcome the frictional resistance of the taphole channel and the coke resistance inside the furnace.
Precise Movement Trajectory: The movement trajectory of the gun nozzle must be extremely accurate to ensure one-time alignment with the iron taphole. Modern designs usually adopt a special linkage mechanism (e.g., four-bar linkage mechanism), which makes the movement trajectory of the nozzle approximately linear when approaching the taphole, so as to protect the taphole clay sleeve from collision damage.
Reliable Sealing and Thermal Insulation: Given the extremely high-temperature working environment, the equipment must be equipped with a complete set of thermal insulation shields and cooling systems to prevent high-temperature radiation from damaging hydraulic components and seals.
Evolution and Intelligent Development TrendsEarly steam-driven clay guns have been phased out due to insufficient thrust. Although electric-driven clay guns feature a simple structure, their thrust improvement is limited and they are prone to wear. The advent of hydraulic clay guns has addressed these drawbacks. Currently, with the advancement of Industry 4.0, intelligent clay gun robots are emerging. These robots integrate AI visual recognition technology, which enables automatic identification of taphole conditions and fully automated, unmanned taphole sealing operations, thereby further enhancing operational safety and efficiency.
In summary, the blast-furnace clay gun is a key node that links the "dynamic" and "static" states, as well as the "opening" and "closing" operations of a blast furnace. It is not only a guardian of the blast furnace’s long campaign life and smooth operation, but also an epitome of technological progress in the iron and steel industry. From the cumbersome machinery in the early days to the sophisticated and intelligent equipment today, every technological iteration of the blast-furnace clay gun has been contributing to the high efficiency, safety and green development of iron and steel production.
