Real-time calculation and display of slag content in the steel stream, and judgment of slag tapping timing combined with set alarm thresholds;

Recognition of morphological variation characteristics of the steel stream and detection of overall light intensity changes to assist in advance prediction of slag tapping timing;

Automatic tracking and capturing of steel stream boundaries to eliminate background interference and improve detection sensitivity and alarm accuracy;

Automatic estimation of total tapping weight and cumulative slag tapping volume; automatic identification of tapping start time and automatic activation of detection;

Storage and playback of historical data from the tapping process; audible and visual alarms triggered upon slag detection, with output signals for closing the sliding gate nozzle or activating pneumatic slag stopping equipment;

Perfect compatibility with all types of slag stopping methods (sliding gate slag stopping, pneumatic slag stopping, slag stopper plug/ball slag stopping)

Technical Specifications

Sensor identification wavelength band: 8–14 μm

Image sampling frequency: 50 Hz

Sensor operating temperature range: -40 °C to 80 °C

A/D conversion precision: 14 bit

System response time: 0.05 s

Detection efficiency: Over 99%

# Equipment Installation

The installation process will not disrupt production, and almost no modifications will be made to on-site equipment.

# In-Process Inspection

Non-contact fully automatic inspection is adopted, and the inspection procedure does not interfere with regular smelting operations.

# Sensor Protection

Sensors are hermetically protected by double-layer stainless steel outer housings. Equipped with automatic sensor temperature regulation and automatic lens dust removal functions, they are applicable to harsh environments at steelmaking production sites featuring high temperatures, dust, vibration and other adverse conditions.

# Slag Detection Algorithm

Customized slag detection algorithms and alarm strategies are developed to match the distinct characteristics of converters and electric furnaces. During tapping, the system self-learns molten steel flow characteristics and predicts the characteristic range of steel slag, instead of relying on absolute characteristic values of steel slag and molten steel for judgment. This enhances the system’s adaptability to various steel grades and diverse production processes.

Control the amount of slag carried over from the converter. While boosting the yield of molten steel, slag carry-over is minimized, phosphorus reversion in molten steel is effectively controlled, and the cleanliness of molten steel is improved.

Significantly reduce the thickness of ladle slag. Field applications demonstrate that the ladle slag thickness is cut by over 25% compared with manual operation, and slag thickness control remains stable.

Cut consumption of deoxidizers and alloys to lower material costs.

Extend the service life of ladles. By controlling the slag entrapment in ladles, erosion of ladle refractory linings by steel slag is alleviated, thus prolonging ladle service life.

Reduce abrasion of tapping holes and inner nozzles caused by steel slag, extending their service lives.

Lower workers' labor intensity and mitigate the impact of human factors: In high-temperature and high-dust working environments, long-term visual inspection of slag entrainment in steel streams impairs eyesight and causes physical fatigue. The adoption of this system alleviates such occupational hazards.

Case Sharing of Infrared Converter

Baosteel Zhanjiang Iron & Steel Co., Ltd. was inaugurated at Jinhai Hotel in Zhanjiang City, Guangdong Province on May 25, 2011. The company eliminated 10 million tons of backward steelmaking capacity in Guangdong Province. The Zhanjiang Iron and Steel Project was designed and constructed as a steel plant with an annual output of 10 million tons, with a total investment of 69.7 billion yuan.

On May 24, 2012, the official website of the National Development and Reform Commission of China released important news that the project would officially break ground on Donghai Island of Zhanjiang on May 31, 2012.

The No.1 blast furnace of the Baosteel Zhanjiang Project was put into operation in October 2015, with the supporting No.1 and No.2 converters commissioned for use simultaneously.

The infrared converter slag detection system identifies slag carry-over during tapping by leveraging the differing radiation characteristics of molten steel and slag within the infrared frequency range. The infrared sensors of the tapping slag detection system are installed at a horizontal position approximately 10 to 30 meters away from the converter tapping spout, keeping them clear of high-temperature zones and extending their service life. Furthermore, the sensors feature built-in temperature control, automatic dust removal, and sealed protective metal housings to enhance overall system reliability. This system delivers precise detection, convenient installation and maintenance, and high operational dependability.

After multiple comparative evaluations of products from domestic and overseas manufacturers, on-site investigations and technical verifications conducted by Baosteel’s steelmaking specialists, this system was ultimately adopted for the Zhanjiang Project. The Baosteel Zhanjiang converters boast a tapping capacity of 300 tons, making them the largest converters in China, which carries landmark significance for our industry. The fully automatic control realized by matching infrared slag detection with sliding gates on a 300-ton converter marks the first such trial among steelmaking enterprises worldwide.

From September 21 to September 30, 2015, Hangzhou Pucheng Teddy Industrial Co., Ltd. completed the installation of infrared slag detection equipment for No.1 and No.2 converters at Baosteel Zhanjiang Iron & Steel. The equipment was commissioned alongside the sliding gate slag stopping system on October 1, 2015, and all equipment debugging was completed successfully by October 29. To meet the requirements stipulated in the equipment technical agreement, a performance acceptance test for the equipment was carried out on October 30 through consultation with the plant. Detailed test results are as follows:

Acceptance Plan

Acceptance target specified in the technical agreement: Acceptance tests shall be conducted simultaneously on the two sets of systems installed on the two converters. The test shall assess the accuracy of furnace lifting alarms of the systems, with a target alarm accuracy rate of 98% over a continuous test run of 100 heats, while the systems operate in linkage with sliding gate control.

Acceptance Data

Data collection period: October 30, 2015 to November 9, 2015

Detailed statistical data:

No.1 Converter: A total of 125 heats of data were collected, including 123 valid heats, achieving an alarm accuracy rate of 99.19%.

No.2 Converter: A total of 128 heats of data were collected, including 115 valid heats, achieving an alarm accuracy rate of 99.26%.

The following are on-site installation photos of Baosteel Zhanjiang
(Click to watch the detailed case video)