Recently, the project “Research and Application of Intelligent Converter Tapping Technology” won first prize at the Shougang Science and Technology Awards. The successful development and application of this achievement indicates that Shougang has independently mastered the automatic tapping technology of large-tonnage converters, laying a solid foundation for realizing the intelligentization of the whole process of converter steelmaking.

In recent years, a large number of digital transformation application scenarios have emerged in domestic iron and steel enterprises, and some steel mills have introduced automatic tapping technology successively, but there are problems such as small tonnage, imperfect functions and low degree of independent controllability of core technologies in most steel mills. In order to promote the intelligent upgrading of Shougang’s iron and steel industry, according to the principle of “filling up” the weak links of digitalization formulated in Shougang’s 14th Five-Year Plan for Intelligent Manufacturing Technology Innovation, the Technology Research Institute joined forces with the Stock Company and Jingtang Company to set up a team to research intelligent converter tapping technology.

Automatic tapping is a functional application project covering image recognition, algorithm optimization, multi-equipment cooperative control and multi-major cooperation, which has high requirements for the reliability and safety of the system. The main goal is to control all the equipment related to converter tapping according to the process requirements, including the converter body, molten steel car, alloy chute, slide plate slag blocking mechanism, etc., thereby realizing the fully automatic operation of the tapping process.

In traditional converter tapping, the slag overflow at the furnace mouth depends entirely on visual observation and adjustment, and the working environment of the operators is difficult, but there are no means to sense the slag overflow at the furnace mouth in real time in an automatic state. To solve this pain point, the project team decided to introduce image recognition technology into the slag overflow prevention detection method of automatic converter tapping. However, when analyzing the tapping image, it was found that the large amount of dust emitted when adding alloy, and the sudden change of brightness caused by high-temperature molten metal during tapping, affected the imaging effect, which made it impossible to accurately judge the slag overflow. To solve this problem, team member Liu Kedong independently developed a dust recognition algorithm and brightness compensation algorithm which make the brightness of the image change smoothly during the tapping process, thus effectively solving the interference and realizing the automatic detection of slag overflow at the furnace mouth.

In the middle of the debugging process, new problems appeared on site. When the converter was tilted at a small angle, jam and abnormal noise occurred which seriously affected the control accuracy of the converter. After overhauling and maintenance, the team still could not solve the problem and encountered a bottleneck in tackling key problems. Late one night, while waiting for the shuttle bus, team member Wang Bingkui saw vehicles in the distance coming quickly and stopping steadily. The anti-lock braking system (ABS) used in the braking of the vehicles suddenly enlightened him. A quick and accurate inching brake could not only stop the converter quickly, but also reduce the wear on the brake system. With this new idea, the team quickly engaged in scheme design. In order to fully grasp the operation habits of the shaking workers in different shifts, the team members waited in the shaking room all day for the key six minutes of each tapping. They observed and recorded carefully for fear of missing any details. After summarizing the rules and optimizing the system, the problems of jamming and abnormal noise of the converter were finally successfully solved, and the angle of the converter was accurately controlled within 0.1 degrees.

In the tapping process, the tilting angles of the ladle car and furnace body need to be closely coordinated. In order to achieve safe production and stable operation, the positioning system of the ladle car is very important. Laser range finders or visual positioning is adopted in most similar car systems. However, these methods are easily disturbed by the surrounding vehicles, personnel and dust, which is also the main reason for the failure of automatic tapping systems in many steel mills. When debugging the weighing system of the ladle car, the project team found that the weighing system wirelessly transmitted data to the external system through sensors installed on the ladle car. Enlightened by this, the team innovatively developed wireless positioning technology for ladle cars. After continuous optimization in the two stages of laboratory testing and field implementation, the success rate of the positioning system was greatly improved to over 98%, the positioning is stable and accurate, and the technical level has reached the international advanced level.

In order to ensure the safe and stable automatic tapping operation of the converter, it was necessary to complete the trial operation of 50 furnaces without load and 100 furnaces with load before it could be officially put into operation. Ding Guohui of the Jingtang Steelmaking Department led a team to the Joint Stock Company for technical exchange, and Jiang Tengfei of the Joint Stock Company’s Steelmaking Department patiently taught his debugging experience. On this basis, the team organized several scheme seminars and formulated several sets of emergency plans to ensure the success of the heat test. Afterwards, in order to communicate and deal with problems at any time, the project team stayed on duty day and night, eating and living with the steelmaking personnel and shaking personnel until all the steelmaking teams could operate skillfully.

The successful application of the intelligent converter tapping system can not be separated from the cross-specialty cooperation of many departments. The team consists of elite forces from the Technical Research Institute, Qianshun Technology Center, Jingtang Technology Center, Joint Stock Company, Jingtang and other units, including automation professionals, experts in the steelmaking process, scientific research personnel and on-site front-line operation experts. After making concerted efforts and giving full play to their strengths for five years, they successfully developed intelligent converter tapping technology with completely independent intellectual property rights and opened up the “last mile” of intelligent converter steelmaking. At present, this achievement has been put into application in several converters of the Joint Stock Company and Jingtang, and is being continuously promoted.

According to Wang Ce, Project Leader from the Metallurgical Process Research Institute of the Shougang Technology Research Institute, in recent years, Shougang has carried out a series of technological innovations in intelligent steel manufacturing, from the development of intelligent detection equipment to the improvement of the intelligence level of each process, and then to the smart factory demonstration project, which can be described as multi-point efforts in full bloom. In the next step, the team will continue to work intensively at Shougang. According to the route of “demonstration first and then promotion”, it is making contributions to promoting the digital intelligence upgrading of the steel industry.