Case study of H-series right angle gearbox for vertical long axis semi submersible turbine return water pump in mine tailings pond

This case study focuses on the renovation project of the return water transportation system in a large metal mine tailings pond. A heavy-duty anti-wear H-series right angle gearbox is used to drive a vertical long shaft semi submersible turbine return water pump, which solves the core pain points of traditional direct drive in high slag content, strong impact, and multi dust mining conditions, such as limited space, rapid component wear, and axial thrust overload. It achieves long-term continuous and stable operation of the tailings pond return water system and completely avoids the major safety risks of dam failure caused by tailings pond drainage failure.
⛏️  Project background and original pain points
The total storage capacity of the tailings pond in this mine is 8 million cubic meters, which is a typical valley type large-scale metal mine tailings pond in China. The supporting return water system is designed to transport a daily clarified water volume of 120000 cubic meters of tailings. The return water contains a large amount of tailings fine sand and slag particles. The original system used a conventional motor-driven vertical long axis semi submersible turbine return water pump scheme, which exposed multiple fatal safety hazards during operation:
The spatial layout is severely limited: the underground pump room of the tailings pond has a floor height of only 3.2m, and the vertical motor is directly stacked above the pump body. The total axial height of the unit exceeds 3m, and there is insufficient space for daily operation and maintenance of the crane. When dismantling the impeller of the pump body and cleaning the slag for maintenance, the top pipeline of the pump room must be temporarily removed, and a single maintenance takes more than 72 hours. The return water system is in a non standby state for a long time, and the risk of exceeding the water level of the tailings pond is extremely high.
Frequent high slag impact overload: The fine sand content in the tailings in the return water exceeds 3% for a long time, and the axial thrust fluctuation amplitude during pump operation reaches 60%. The original vertical motor has a rated bearing capacity of only 65000N, which is affected by alternating impact loads for a long time. On average, bearing burnout faults occur within 6 months, and the unplanned failure rate of the return water system is as high as 20%, directly threatening the water level safety of the tailings pond.
Rapid wear and tear in dusty environments: A large amount of mineral dust particles are dispersed in the air around the tailings pond, and the sealing protection level of ordinary gearboxes is insufficient. Mineral dust is prone to invade the interior, causing rapid abrasive wear on the gear meshing surface. On average, tooth surface pitting and vibration exceeding the standard faults occur within 10 months, and the equipment maintenance cost is more than 4 times that of ordinary clean water pumps.
High energy consumption: The original direct drive scheme cannot flexibly adjust the output speed of the pump, and can only control the return water flow through the outlet valve throttling, resulting in a large amount of energy being wasted. The annual power consumption of a single return water pump exceeds 4.5 million kWh, and the system's operating energy consumption far exceeds the industry average level.
🛠️  Customized selection scheme for H-series right angle gearbox
For the special working conditions of high slag content, strong impact, and high dust in mining tailings ponds, the heavy-duty anti-wear upgraded H-series right angle gearbox is selected, and the core configuration is fully adapted to the strict requirements of tailings pond scenarios:
Accurate matching of core parameters:
Suitable for a horizontal motor with an input power of 900HP (approximately 670kW), with 30% power redundancy reserved. The rated input speed is 1500rpm, and the pump output speed is 2025rpm through a customized transmission ratio of 1.35:1, fully matching the operating point of the tailings return water pump with a rated flow rate of 1500m ³/h and a head of 80m.
Upgraded heavy-duty thrust roller bearings, with a rated axial thrust bearing capacity of 125000N, fully covering the maximum instantaneous axial thrust of 105000N under slag impact, and reserving 19% of thrust redundancy, completely solving the problem of bearing overload caused by alternating axial impact loads.
Special optimization of mining conditions:
The gears are treated with 20CrMnTi alloy steel carburizing and quenching, with a surface hardness of HRC60 or higher. Combined with high-precision gear grinding technology, the anti-wear ability is more than twice that of ordinary gears, which can resist slight wear caused by mineral dust intrusion and extend the service life of the gears.
The shaft end adopts a multiple dust-proof sealing structure, with a protection level upgraded to IP66, completely blocking the entry of tailings and mineral dust particles into the gearbox, and preventing tooth wear caused by mineral dust entering the lubricating oil.
Layout and operation adaptation optimization:
The horizontal motor is horizontally arranged in the safe area on the ground of the pump room. It drives the vertical long shaft return water pump vertically after turning 90 degrees through the H-series right angle gearbox. The total axial height of the unit is reduced from 3m to 1.7m, perfectly adapting to the narrow vertical space of the underground pump room. There is no need to modify the original pump room steel structure, greatly reducing the construction cost of the modification.
Equipped with independent forced oil injection lubrication and external cooling system, the oil temperature can be stably controlled below 55 ℃. At the same time, an online oil monitoring sensor is installed to detect the content of metal abrasive particles in the lubricating oil in real time, predict the wear status of gears and bearings in advance, and avoid sudden failure during unmanned periods.
✅  Actual testing effect of project implementation
After the renovation project was put into operation, it operated continuously for 42 months without major faults, and its performance indicators far exceeded the requirements of mining safety regulations
Significant improvement in reliability: The heavy-duty thrust bearing of the gearbox fully carries all the alternating axial loads of the pump, and the vibration value of the shaft system remains stable below 2.9mm/s, completely eliminating the original motor thrust bearing burnout fault. The continuous fault free operation time of the equipment has been extended from 6 months to 42 months, and the reliability of the return water system has been improved to 99.95%, completely eliminating the major safety hazard of tailings pond water level exceeding the standard and dam collapse.
Significant energy-saving benefits: By accurately matching the gearbox transmission ratio and eliminating the original valve throttling regulation, the system transmission efficiency has been improved to 97%. A single return water pump can save 3.1 million kWh of electricity annually. Calculated at a mining industry electricity price of 0.7 yuan/kWh, the annual direct increase in revenue exceeds 2.17 million yuan, and the entire renovation cost can be recovered in 10 months.
The anti-wear performance has been greatly enhanced: IP66 level multiple dust-proof seals completely block the intrusion of mineral dust, and the cleanliness of the lubricating oil inside the gearbox remains within NAS8 level for a long time. The gear wear is only 50% of the industry average level, and the equipment lubricating oil replacement cycle has been extended from 3 months to 18 months, reducing annual operating and maintenance costs by 75%.
Significant improvement in operation and maintenance efficiency: After the total height of the unit has been significantly reduced, daily slag cleaning and maintenance can be directly carried out using the conventional crane in the pump room for lifting. The dismantling and maintenance time for a single pump body has been reduced from 72 hours to 8 hours, and the downtime for maintenance of the return water system has been reduced by 90%, greatly reducing the safety risks of high water level operation in the tailings pond.
📌  Summary of core project experience
When selecting scenarios for mining tailings ponds, it is necessary to choose customized H-series models with high thrust bearing capacity, reserve more than 30% power redundancy, and increase the operating coefficient KA value to 2.0~2.5 to resist strong alternating impact loads caused by slag containing media. It is prohibited to directly use standard models for ordinary clean water pumps.
In a dusty mining environment, it is necessary to upgrade the protection level to IP66 and equip it with multiple dust-proof sealing structures to prevent mineral dust from entering the interior and causing abrasive wear on the tooth surface, which is the core key to extending equipment life.
The H-series right angle gearbox solution can be directly replicated and promoted to various high slag and strong impact mining scenarios such as metal mine tailings pond return water system, ore dressing plant slurry conveying system, coal mine drainage system, etc. It is currently the mainstream technical route for improving drainage systems, reducing costs and increasing efficiency, and ensuring intrinsic safety in mines.
Project Background:
A certain mine tailings pond adopts a floating water intake pump station, equipped with a vertical long shaft pump and an H-series right angle gearbox, for tailings return water/water intake.
Technical points:
·Installation method: Floating (varies with water level).
·Pump type: Vertical long shaft semi submersible turbine pump.
·Special challenge: high wear of tailings slurry and large fluctuations in water level.
Analysis:
The tailings working condition is one of the most demanding application scenarios for the H series right angle gearbox:
·The pumped medium contains high concentration slurry, and the gearbox needs to be equipped with reliable seals (such as double lip seals) to prevent slurry from entering.
·Floating installation requires the connection between the gearbox and the pump to have a certain degree of flexible compensation capability.
·Regular inspection of gear wear status is required under high wear conditions.