The latest technological development of mine hoists

The latest technological development of mine hoists

Focusing on the rapid development of mining hoisting technology, this article elaborates on the technological innovations of hoisting equipment in large-scale, structural design, hydraulic braking system, control and transmission system, and promotes multiple key technological breakthroughs in heavy-duty and ultra deep hoisting machines; Introduced the application of the main auxiliary equipment matched with the hoist in new technologies, new processes, and new materials; It has been pointed out that high-power frequency converters are one of the research and development directions that domestic manufacturers need to focus on.

The hoist is the main equipment in mines, used for lifting personnel and materials. According to the working principle, the hoist can be divided into single rope winding type and multi rope friction type. The mine hoisting equipment consists of four parts: main engine, gate control system, electric motor, and electric control system, as well as other supporting auxiliary machines. In recent years, with the increasing demand for ultra deep, heavy load, and high-speed mining, the large-scale development of mine hoists has been rapid, and significant technological progress has been made in each component. Many mines in China have already used large and extra large hoists. This study mainly introduces the latest technological progress in improving equipment from the aspects of host technology, gate control technology, motor technology, electrical control, and other auxiliary equipment.

1. Development of host technology 1.1 Large scale With the increasing scale of equipment, relevant units have timely revised the product standards of the main categories of mine hoists, supplemented large specifications, and many large specification hoisting products have been put into operation
2. (1) The GB/T 20961-2018 “Single rope winding mine hoist”, which was implemented on October 1, 2018, is a revised standard. This standard increases the maximum size of a single cylinder to JK-5 × 3.5 and the maximum size of a double cylinder to 2JK-6 × 2.5. The maximum specification of the single tube elevator currently in operation is JK-5 × 2.4, and the maximum specification of the double tube elevator is 2JK-6 × 2.4. (2) The GB/T 10599-2023 “Multi rope Friction Hoist”, which will be implemented from July 1, 2024, is a revised standard for multi rope friction hoists. This standard increases the maximum specifications for floor standing to JKMD-7.5 × 6 and well tower to JKM-7.5 × 8, and significantly enhances the lifting capability of products of the same specifications. The maximum specification of the floor standing elevator currently in operation is JKMD-6.2 × 4, and the maximum specification of the well tower type is JKM-6.75 × 6. (3) The JB/T 12193-2015 “Drilling Hoist”, which was implemented on October 1, 2015, was the first standard to be formulated for drilling hoists. The maximum specification of the single tube drilling hoist is JKZ-5.5 × 5, and the maximum specification of the double tube drilling hoist is 2JKZ-5.5 × 4. The maximum specification of the single tube drilling hoist currently in operation is JKZ-5.5 × 3, and the maximum specification of the double tube drilling hoist is JKZ-5 × 3. (4) The JB/T 13006-2017 “Underground Electrical Explosion proof Single Rope Winding Mine Hoist and Mining Hoist”, which was implemented on July 1, 2017, is the first standard to be formulated for underground explosion-proof hoisting winches and hoists. This standard takes the breakthrough point of “the rope diameter ratio (D/d) of the downhole winch and hoist is 80, while the downhole hoist can be reduced to 60″, which greatly increases the lifting capacity of the downhole winch and hoist. The maximum specification for a single cylinder in this standard is JKB-4.5 × 3, and the maximum specification for a double cylinder is 2JKB-5 × 2.3. The maximum specification of the single cylinder currently in operation is JKB-4 × 2.4, and the maximum specification of the double cylinder is 2JKB-3.5 × 2.。
3. 1.2 Structural Innovation (1) The development of super large sectional friction wheels, sky wheels, and guide wheels is limited by transportation. The friction wheels, sky wheels, and guide wheels of large-diameter elevators all adopt sectional structures, which means they are shipped separately and assembled on site. Each manufacturer has different sectional structures, but they generally follow the principle of “precise positioning+reliable connection”. The two sections of the structure are accurately positioned through positioning pins and connected by high-strength bolts. At present, a series of products have been produced, including friction wheel diameters of 6.75, 6.50, 6.20 m, crown wheel diameters of 6.2, 6.0 m, and guide wheel diameters of 6 m. (2) The upgrade of the multi rope pulley device adopts multiple upgrade technologies such as integrated processing of bearing shells, positioning block positioning, and addition of bearing lubrication grooves, which eliminates the faults of bearing nut cutting and abnormal noise, and extends the service life of the pulley. (3) The multi rope pulley device supported by rolling bearings replaces the support of the pulley from the bearing shell to a new type of pulley device with rolling bearings, reducing rotational resistance, avoiding bearing shell wear, and reducing maintenance workload for refueling. (4) The multi rope lifting machine milling groove device using high-speed milling cutters adopts an active milling mode of high-speed milling cutters, replacing the passive turning mode of the original turning tool, which improves the efficiency and accuracy of rope groove processing and balances tension. (5) The use of split rolling bearings near the motor end allows for easy replacement or maintenance of bearings without the need to disassemble the motor, reducing downtime. This technology can also be used to modify old upgraded products. In 2015, a domestic manufacturer renovated the transmission end bearings of the JKM-3.5 × 6Z III elevator at Beiminghe Iron Mine in Hebei Province. The original bearing seat was used to replace the integral rolling bearings with segmented rolling bearings. After the renovation, the equipment has been running steadily until now. (6) The centralized lubrication device for bearing grease is composed of a grease pump, distribution valve, pipeline, and joint. It can accurately, timely, quantitatively, and reliably perform centralized automatic lubrication on each lubrication point, ensuring lubrication effect and reducing maintenance workload. (7) High specific pressure friction pads are often the bottleneck for selecting friction pads for ultra deep and heavy-duty friction hoists. In 2018, relying on the key project of the Ministry of Science and Technology of China, “Key Technologies for Deep Shaft Large tonnage High speed Lifting Equipment and Control”, a domestic manufacturer successfully developed a new type of high specific pressure friction pad, which was verified through laboratory testing and third-party testing. The specific pressure of the pad can be increased from the original 2.0 MPa to 2.5 MPa. (8) The emergency lifting system is an auxiliary system independent of the main lifting system, which can achieve safe lifting of personnel in extreme situations such as main lifting equipment failure or power outage in the entire mine. This product can be applied to both multi rope friction hoists and single rope winding hoists.

4. Development of Electrical Control System Technology

(1) The unmanned control system realizes centralized monitoring and on-site unmanned operation of the entire process of mine lifting from the machine room to the wellbore, reducing the operation gap time of each link. The system’s operating efficiency has been improved by at least 5%, and the effect of reducing personnel and increasing efficiency is significant.

(2) The smart cage device can achieve an elevator like operation mode, select the destination inside the tank, have vehicle control and display functions, and can have voice and video calls with centralized control personnel; It has functions such as personnel identification and permission management inside the tank, image monitoring and recognition of the cage and the upper and lower areas of each section, as well as automatic detection of the tension of the cage steel wire rope.

(3) The technology of low-speed direct drive high-voltage variable frequency speed regulation has made significant progress in domestic manufacturers’ high-voltage cascade frequency converters. Domestic manufacturers have currently mastered technologies such as high-performance vector control and zero speed hover control for low-speed direct drive synchronous motors, and have developed a 7 MW level high-performance four quadrant frequency converter. Compared with medium voltage three-level frequency converters, it has the advantages of low current, low harmonics, bypass operation for unit faults, and high cost-effectiveness. It adopts a dual frequency converter parallel connection scheme, which can meet the matching requirements of a 7000 kW motor.

(4) The energy-saving technology of low-speed direct drive permanent magnet frequency conversion developed by domestic manufacturers adopts the optimal control strategy of permanent magnet motors, automatically compensates for cogging torque pulsation, and intelligently switches control schemes according to load torque, speed, operating power and other conditions, so that the system always works in the optimal state. This technology has a large starting torque, strong overload capacity at low speeds, and high operating efficiency at high speeds; The static identification function of permanent magnet motor rotor position has high reliability and can be combined with an encoder to automatically achieve rotor position positioning with high accuracy; Built in high-precision permanent magnet motor load observer for torque feedforward control, improving system dynamic response. Combined with high dynamic response characteristics, it realizes the hovering function of the hoist and reduces the mechanical impact of system start stop; Equipped with self-learning function for key parameters of permanent magnet motors, it enables more accurate construction of permanent magnet motor models and achieves efficient and high-performance operation of the system. At present, nearly 20 units of this type of product have achieved application performance.

5 Other supporting auxiliary machines

(1) The steel wire rope has newly developed a 7-strand rope for the main rope, which is a new structure added to the domestic mining standard. This structure is specifically designed for deep well mining based on foreign usage experience, replacing traditional steel wire ropes such as 6 × 36 WS, anti rotation, and triangular strands. This new type of steel wire rope has 7 outer strands, which can improve roundness and reduce vibration; Compaction increases the metal area; More surface exposure facilitates visual inspection; Reinforced core (steel+PPC) improves radial stiffness; The plastic coated core ensures its stability. A new type of parallel clamped flat steel wire rope has been developed for tail ropes. It is woven using rivets, which has better wear resistance and crack resistance compared to traditional weaving methods, thereby extending the service life of the steel wire rope. The weaving structure of parallel clamped flat steel wire rope enables mutual restraint between strands, increasing overall stability and reducing deformation and relaxation of the steel wire rope; The weaving method enhances the load-bearing capacity of the steel wire rope. The reinforcement effect of rivets can increase the strength and stiffness of steel wire ropes, enabling them to withstand greater tensile and load forces; The strands of the steel wire rope are more secure and less prone to loosening, thereby improving the safety of use. After installation, the parallel clamp flat steel wire rope is not tied tightly like the woven flat steel wire rope, but has appropriate activity space and can automatically adjust the balance. Its flat, smooth and even performance is better than that of the woven flat steel wire rope.

(2) The maximum cage size (length x width x height) of the domestically produced super large cage and skip is 10.8 m x 3.8 m x 13.8 m, with a load capacity of up to 150 t and a self weight ≤ 135 t. It will be used in conjunction with the JKM-6.5 x 8P IV hoist in the auxiliary shaft of Shaanxi Coal Caojiatan Coal Mine; The maximum size of the skip (length x width x height) is 2.945 m x 2.21 m x 18.8 m, with a volume of 50 m3, a carrying capacity of up to 75 t, and a self weight of 72 t. It will be used in conjunction with the JKM-6 x 6P IV super large hoist at the Shapinggou Molybdenum Mine of Zijin Jinsha Molybdenum Industry.

(3) The rope changing car is used for replacing the main rope, balance tail rope, and tank rope of the vertical shaft friction hoist. Using specialized mechanized equipment to achieve automated replacement of the main rope, the rope does not fall to the ground throughout the entire process, and personnel only connect the rope head at the wellhead. Dangerous operations are completed by the rope changing vehicle. This device requires fewer people, has a shorter duration, and lower labor intensity, and has been widely used.

(4) The dual code rope selection and exchange intelligent protection device is applied in vertical shaft friction lifting mines, which can achieve multiple functions such as sliding rope protection, dual code rope selection and exchange, automatic rope clamping, etc., facilitating the replacement of pulleys, pads, bearings, containers, etc. This device has been widely used.

(5) The steel belt type anti roll buffer device is a multifunctional anti roll protection device that integrates a buffer device, a towing device, and a collision beam. It uses plastic deformation energy absorption buffering of metal materials to make braking smooth and without rebound. The reverse lock is directly driven by the kinetic energy of the lifting container, preventing the container from sliding in the opposite direction and improving the reliability of the container support. This device has been widely used.

6.The key technologies of heavy-duty and ultra deep elevators are different from conventional elevators in that they have typical characteristics. Conventional technologies are not sufficient to solve the problems of heavy-duty and ultra deep elevators. Therefore, a series of new key technologies have been developed for heavy-duty and ultra deep elevators.

(1) The selection technology for heavy-duty and ultra deep lifting steel wire ropes is the multi rope friction hoist for ultra deep and heavy-duty lifting. The damage mechanism of the lifting steel wire rope is that during the acceleration stage of lifting heavy loads, the lifting side steel wire rope is subjected to the maximum force. Under the action of torsional stress, the upper part of the lifting steel wire rope is loosened and stress is concentrated. The loosened steel wire rope bears bending stress when passing through the friction wheel. If the support force of the steel wire rope core is insufficient, it will cause deformation of the rope strands and increase stress concentration when it bends after loose twisting. When the steel wire rope passes around the friction wheel, the loosely twisted steel wire rope will suddenly twist tightly, causing the internal stress of the steel wire rope to be redistributed. During the process of significant internal stress changes, the steel wire rope experiences reverse bending stress as it passes through the guide wheel and crown wheel, which accelerates the damage of the internal steel wire rope. In addition, increasing the depth of the wellbore will bring about significant alternating stress, corrosion, etc. Therefore, it is necessary to improve the service life of the steel wire rope from multiple aspects such as anti torsion, reducing bending stress, increasing core support, delaying reverse bending, and strengthening anti-corrosion. Based on the above reasons, imported multi-layer anti rotation compacted strand injection molded steel wire ropes are widely used for ultra deep and heavy-duty multi rope friction hoists.

(2) The load dynamic electrical verification technology achieves real-time and accurate measurement of tension and tension difference before operation by installing high-precision tension sensors between the steel wire rope and the container, avoiding overload danger, motor and frequency converter overload, sliding rope and mechanical fatigue, realizing monitoring and interlocking protection, and promoting efficient and safe operation of mine lifting.

(3) Steel wire rope vibration control technology uses the frequency converter’s steel wire rope vibration control function to regulate the power and torque of the motor, achieve controllable adjustment of the system’s acceleration/deceleration change rate and torque change, actively suppress steel wire rope vibration, and achieve smooth operation of the lifting system.

(4) Large auxiliary shaft tank locking technology can achieve stability of the tank cage during loading and unloading of large items. By actively releasing the elastic elongation of the steel wire rope, there is no need to reverse the winch operation; Selective use of dual compensation and locking functions ensures high efficiency during normal lifting and high safety during loading and unloading of large items; When the locking control of the shaking table is not fully unlocked, the shaking table cannot be opened and the cage cannot operate, to prevent damage to the cage and other equipment caused by misoperation of the shaking table. (5) The high-speed smooth parking control technology has a zero speed hovering function, which can achieve a predetermined deceleration and smooth parking, realize electrical braking and hold brake after parking, and effectively suppress the longitudinal jumping of the steel wire rope and container during parking.

(6) Emergency braking gentle control technology adopts a fully digital controller with embedded high-performance chips, which has high braking control accuracy and can automatically adjust the establishment time of braking torque, effectively reducing equipment impact in the early stage of emergency braking, smoothly reducing the acceleration change rate entering or exiting the constant deceleration, and eliminating the elastic vibration of the steel wire rope during the braking process.

7. Conclusion

A hoist is a complex system composed of mechanical, electrical, hydraulic, and auxiliary equipment. Any problem in any link can affect the safe and reliable operation of the hoist. The various components of the upgrading system are manufactured by different manufacturers, and each manufacturer has formed a long-term cooperative and win-win relationship, promoting collaborative development and greatly improving the overall upgrading technology in China. At present, many components such as electric motors, containers, lock tank shaking tables, loading and unloading systems, etc. are not only matched with domestic elevator manufacturers, but also gradually become the matching choice for foreign elevator manufacturers, and the localization rate is steadily increasing. However, high-power frequency converters are still a clear weakness, and there is still a gap between domestic brands and ABB and Siemens. This is a research and development direction that domestic manufacturers need to focus on.

Company Profile

Hebei Xingtang Huaicheng Machinery Equipment Co., Ltd. is an enterprise that integrates design, development, manufacturing, engineering installation, and after-sales service. Our company has advanced production equipment, strong technical strength, complete testing equipment, and strict management system, and is a designated backbone enterprise in the livestock machinery industry.

Our company specializes in producing various models of TMR fully mixed feed preparation machines, solid fertilizer trucks, liquid fertilizer trucks, manure cleaning trucks, feeding trucks, silage reclaimers, throwing trucks, grass bundle crushers, constant temperature drinking water tanks, cow neck shackles, cow beds, cow body brushes, various accessories and other livestock facilities and agricultural machinery.

Our company provides a one-stop service from cattle farm design to installation. No matter where the customer is, our technical personnel will personally conduct technical training on site to improve their operation and maintenance skills and promote harmonious development. Our pursuit is to be innovative, and our aim is to focus on management and improve quality. Hebei Xingtang Huaicheng Machinery Equipment Co., Ltd. sincerely hopes to cooperate with distributors and sister enterprises to achieve common development and contribute to serving agriculture, rural areas and farmers!

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