The project “Development and Application of Hot Charging and Pretreatment Process Equipment for Continuous Casting Sheet Billets”, jointly completely by the Shougang Research Institute of Technology, Shougang Jingtang and Shougang Engineering Company, was granted First Prize of Shougang Science and Technology in 2021. The whole set of technologies developed for this project has independent intellectual property rights, and its successful application plays a key technical supporting role in improving the proportion and temperature of the hot charging and hot delivery of continuous casting sheet billets, and provides an innovation path for energy conservation and emission reduction, and realizing the development of a low-carbon life in the steelmaking field of Shougang.

The hot delivery and hot charging of continuous casting sheet billets are technologies that were successfully developed in the 1980s which played an important role in energy conservation, consumption reduction and yield improvement. However, for the microalloyed steel which is widely used in recent years, great technological bottlenecks are faced in continuing to improve the proportion and temperature of the hot charging of casting slabs. When the hot charging temperature increases continuously, especially when it reaches the two-phase zone, a large number of microalloy precipitates will be separated out, and the coarse and uneven surface of the microstructure after high temperature heating will lead to the appearance of “hot charging process cracks” on the surface of the rolled steel plates. Many domestic enterprises have tried to solve this problem without success, and it has become a common problem in the industry.

Facing the bottleneck problem, Dr. Liu Yang of the Research Laboratory of Wide and Thick Plates of the Shougang Research Institute of Technology stepped forward and set up a multi-sectoral and multi-disciplinary joint research team covering scientific research, design and on-site production. The project team put forward the first hot charging and pretreatment technology of casting slab surfaces based on continuous casting machine bodies in China. The Research Laboratory of Wide and Thick Plates of the Research Institute of Technology undertook basic theoretical research and technology development; the Metallurgical Process Institute was responsible for automatic control system development; the Shougang Engineering Company was responsible for equipment design; and the Jingtang Steel Rolling Department was responsible for industrial experiment and technology optimization. Each group cooperated on carrying out a complete set of technological research on technology, equipment and automation.

In the initial stages of the project, the automatic control development of the whole system was handed over to the Metallurgical Process Institute of Research Institute of Technology. This young team, participating in this kind of engineering project for the first time, took root at the production site, overcame many key problems from water system design to equipment type selection to control system development, and completed the development of the automatic control system with quality and quantity guaranteed.

In the hot test process of the project, the high-temperature casting slabs showed serious bending and deformation after being cooled by a super-large water spray, leading to an inability to cut after casting slab deformation, which had a great impact on production. This was the key difficulty that determined the success or failure of the project. Wang Guolian, Head of the Jingtang Steel Rolling Department, Xie Cuihong, Assistant to the Director of the Biotechnology Laboratory, and Zhao Jing, Chief Operating Head of Slab Continuous Casting, mobilized all forces to face the difficulties and organized on-site technicians to analyze the reasons and adjust the technology with the technical personnel of the Research Institute dozens of times. After working day and night to tackle the key problems, they finally successfully solved the “bottlenecks” of casting slab bending and deformation through effective measures.

During the long-term production and application of the casting slab hot charging and pretreatment system, the problem of uneven water spraying emerged. Liu Pengtao, Chief Engineer of the Shougang Engineering Company, and Wang Guoyi, engineer, responded quickly and optimized the design of the nozzle of the fan sections, enabling the technology to realize application and iteration quickly, and ensuring the normal operation of the spraying function.

On-site professionals of wind, water, electricity and gas pooled the wisdom and efforts of everyone in engineering construction, equipment installation and debugging, accidental fault handling, etc., bravely shouldered heavy burdens and effectively dealt with unexpected situations, providing a strong guarantee for the smooth development and final application of the project.

For the project “Development and Application of Hot Charging and Pretreatment Process Equipment for Continuous Casting Sheet Billets”, applications were made for four domestic invention patents, one international invention patent was accepted and one standard was filed. For this project, more than ten key technologies were developed one by one, and the related achievements were authenticated by the China Iron and Steel Association as pioneering and leading technologies in the world. This technology was put into production and application in Jingtang’s No. 6 continuous caster in October 2020, and the hot charging rate of casting slabs increased by 45 percentage points on average. The highest surface temperature of the hot charging of high-quality microalloyed steel slabs can now reach 658℃, saving heating furnace energy by 14.4% on average, reducing CO2 emissions by 10 kg per ton of steel, and comprehensively lowering the cost by RMB 11 per ton of steel.