Traditional inspection methods for lifting steel rope have various drawbacks. From the perspective of modern coal mine construction, it is necessary and feasible to use TCK weak magnetic steel wire rope detection technology to monitor the safety of steel wire rope. This is a beneficial exploration and practice of modernization mode for lifting steel rope safety supervision.

        CLC No.: TD532 Document Code: B Article ID: 1003-496X(2011)01-0148-02

　　With the continuous deepening of modern coal mine construction, most state-owned coal mining enterprises in China are creating digital and information-based mines in order to achieve intrinsic safety in coal mines. However, the safety management of mine transportation and hoisting equipment still remains at the traditional management stage, which is incompatible with modern coal mine management. There is an urgent need to apply advanced modern management methods to fundamentally change this backward situation.

　　1 Modern coal mine lifting and transportation equipment steel wire rope management calls for advanced detection technology

　　The hoist plays a very important role in coal mine production, and is responsible for the transportation and lifting of workers, raw coal, materials, and other items. In hoisting transportation, the steel wire rope is crucial for the safety of employees, and directly relates to the safety of mining equipment and property, acting as the "lifeline" of the mine's "throat". Therefore, the management of lifting steel wire rope is a key and difficult point in coal mine electromechanical equipment management.

　　In the Datong Coal Group, despite the constant attention paid to the safe operation of lifting steel wire ropes, due to the lack of reliable detection methods, the group has long relied on manual visual inspection methods and regular rope replacement measures to ensure the safe operation of lifting steel wire ropes. This outdated and unreliable method has left the use and management of lifting steel wire ropes with "five major difficulties" in terms of safety supervision.

　　(1) It is unsafe. According to the statistics in the "Chinese Coal Mine Accident and Expert Commentary Collection", by 1995, 19,871 people died in coal mine transportation and lifting accidents, accounting for 15.06% of the total death toll, which is only second to roof and gas accidents and is the third major disaster accident in the coal industry. Therefore, steel wire rope has become a highly dangerous component in various transportation and lifting equipment in coal mine enterprises.

　　(2) It is uneconomical. In order to avoid steel wire rope accidents, various steel wire rope using enterprises generally adopt the measure of regular replacement. This practice of replacing the rope with a new one upon expiration has led to an increase in the cost of using steel wire rope. According to statistics in Japan, more than half of the steel wire ropes that were forced to be replaced had a strength of more than 90% of the new rope strength, and many had a strength of more than 100%, which means that they were still in the break-in period. However, according to the survey results in the United States, about 70% of the steel wire ropes that were forced to be replaced had little or no strength loss.

　　(3) Efficiency is low. Manual inspection is inefficient and wastes a lot of production time. Taking coal mining as an example, according to the requirements of the "Coal Mine Safety Production Regulations", steel wire rope should be inspected once every shift, and each inspection takes about 1 hour. Each operating mine only has one item of steel wire rope detection, so more than 330 hours of valuable production time are wasted every year. According to the production capacity of 1 million tons per year, 200 tons of coal can be produced per hour, so 330 hours less than 66000 tons of coal. If the price of coal is 500 yuan/ton, the economic losses will reach 33 million yuan every year. There are 52 pairs of operating mines in Datong Coal Group, only one item of steel wire rope detection waste, the production time lost one year, the economic losses are very large.

　　(4) Unreliable. Manual inspection can only partially detect obvious external injuries to steel wire ropes, but it is impossible to detect internal wear, corrosion, broken wires, and especially fatigue and other injuries. Therefore, many significant accident hazards cannot be detected.

　　(5) Great Hazard. If a steel wire rope breaks in an accident, it will inevitably cause significant harm. The equipment, mine repair, and production shutdown caused by steel wire rope accidents will result in enormous indirect losses. If the accident causes casualties, the harm to the families of the victims is impossible to measure and make up for with economic compensation.

　　As an urgent need to change the current passive management situation of steel wire ropes, Datong Coal Mine Group, like other coal mining enterprises, has been actively seeking reliable non-destructive testing equipment for steel wire ropes. They hope to use advanced and reliable detection technology to improve the safety management level of transportation and lifting equipment in the same coal mine.

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　　2 TCK.W portable NDT instrument improves the management of steel wire rope

　　Improving the safety of steel wire rope operation has always been a difficult task in the safety management of mining hoists. The working conditions of mine hoisting are harsh and complex, and steel wire ropes are prone to corrosive damage due to long-term exposure to groundwater, acid and alkali corrosive substances or gases. During the lifting operation, the steel wire rope is constantly subjected to various stress concentrations such as squeezing, stretching, bending, tension and compression, resulting in fatigue. During production operations, the steel wire rope is accidentally damaged or injured due to improper human operation. There are also other factors such as steel wire rope manufacturing, transportation, warehousing, etc., which can also cause damage to the steel wire rope. These damages can cause steel wire rope accidents at any time.

　　To solve the above-mentioned safety management difficulties, eliminate accident hazards, and effectively prevent accidents, it is undoubtedly necessary to apply advanced detection methods. There are 52 pairs of main and auxiliary mines in Datong Coal Group, with large production loads and high transportation and hoisting safety. To ensure the safe operation of steel wire rope for hoisting, TCK's portable non-destructive testing instrument was introduced in 2006. Although it has greatly improved the detection efficiency and safety management level of steel wire rope in Datong Coal Mine, it has also made a great step forward in improving the safety management of hoisting equipment. However, in practical use, we also feel that the portable testing instrument has not completely eliminated the impact of human factors on the intrinsic safety of the equipment. In addition, the mine conditions are complex, and for safety reasons, some lifting steel wires cannot be detected by personnel holding instruments. Therefore, to completely solve the problem of safety supervision of mine hoisting steel wire rope, further innovative management models are needed. The best solution is to achieve on-line real-time continuous detection of steel wire rope.

　　To explore the advanced management model of online automatic detection for steel wire ropes, Datong Coal Mine has made certain efforts. However, due to the lack of breakthrough in traditional strong magnetic detection technology, it has been unable to overcome the disadvantage of poor passability and implement online real-time detection. Therefore, online real-time detection has long been a desire. It was not until the emergence of weak magnetic detection technology that online real-time detection of steel wire ropes became a reality. This is because the sensors used in weak magnetic detection have high sensitivity, which is tens of thousands of times higher than that of Hall elements. Therefore, even if the spacing between the detecting body and the measured object reaches 30mm, signals can still be accurately captured to achieve wide-range non-contact detection. This major technological breakthrough determines that currently only weak magnetic detection technology can achieve true online real-time automatic detection for steel wire ropes. TCK Company, which owns weak magnetic detection technology, has developed the TCK online real-time automatic detection system for steel wire ropes after more than one year of development. This system adopts the innovative core technology of weak magnetic detection and is designed according to the safety operation needs of major transportation and lifting equipment. Through the mode combination detection device with customized equipment, intelligent data acquisition and conversion device, photoelectric counting speed measurement device, acoustic and optical warning device, and terminal main control device, it can automatically detect internal and external injuries such as broken wires, wear, corrosion, and fatigue of steel wire ropes online in real-time. It can also automatically analyze various injury information, store and record detection results, print detection reports, and effectively eliminate various drawbacks of manual detection.

　　In 2009, TCK's steel wire rope online real-time automatic detection system was equipped in 21 pairs of main mines in Datong Coal Mine, which are used for single-rope winding, four-rope ground friction, and six-rope ground friction hoisting machine steel wire rope online detection. With the installation and use of TCK's steel wire rope online real-time automatic detection system, a new safety supervision model for steel wire rope was created in Datong Coal Mine. With the use of TCK's steel wire rope online real-time automatic detection system, the hoisting steel wire rope of these mines is always under safe and controlled detection, fundamentally preventing accident hazards and ensuring safety. Since testing can be completed during normal production, production and testing are integrated, which increases effective working time, improves production capacity, and significantly reduces the idle energy consumption used specifically for steel wire rope detection. In addition, the use of this system can also scientifically extend the service life of steel wire rope, save time for rope replacement, and reduce the cost of using rope. In short, the use of this advanced online real-time automatic detection system for steel wire rope has completely changed the backward status of Datong Coal Mine's safety management of hoisting machine steel wire rope, solved the three conflicts of "hidden dangers, waste, and inefficiency", and achieved the three management goals of "safety, cost reduction, and efficiency".

　　The application of TCK steel wire rope online real-time automatic detection system has innovatively improved the safety supervision mode of steel wire rope, making the transportation and lifting equipment management of Datong Coal Mine Group enter the digital, intelligent and automated stage, and successfully realizing the smooth integration with the modern management of Datong Coal Mine Group in all aspects.

　　About the Author

　　Wang Tianzhong, male, born in September 1973, is a member of the CPC. He graduated from Taiyuan University of Technology with a bachelor's degree in electrical automation. He is an assistant engineer. Currently, he is the head of the mechanical section of the mechanical and electrical department of Datong Coal Mine Group. He has published more than ten papers, mainly engaged in the technical research and field management of mine mechanical and electrical equipment.

　　References:

　　Inspection and Accident Case Analysis of Mining Steel Wire Rope (Coal Industry Press, 1999)

　　"On-line Nondestructive Quantitative Method and Determination Rules for Steel Wire Rope (Cable)". MT/T970-2005