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High pressure grinding rolls (HPGR) is used in the processing of high-hardness and high-abrasive ores in mines. The working environment is extremely harsh (ultra-high pressure, strong impact, high wear, and mineral powder intrusion). The replacement frequency and cost of its wearing parts are significantly higher than those of cement roller presses. The following are the parts that need to be replaced most often and their reasons:

Core parts of the roller surface (directly subjected to ore impact and extrusion, with the most severe wear):

Carbide roller nails/wear-resistant column nails: These are the core parts that wear the fastest and are replaced most frequently. They are directly embedded in the roller surface and withstand the severe extrusion, cutting and impact wear of hard ores (such as iron ore, gold ore, Mohs hardness 6-7) under ultra-high pressure (up to 300MPa). Wear is manifested as the nail head being flattened, broken or falling off, resulting in roller surface failure, a sharp drop in crushing efficiency and poor cake quality. Under hard rock mining conditions, the replacement cycle is usually only 3-6 months.

Roller/matrix: After the roller nails fall off, the exposed matrix or roller edge area is directly subjected to ore wear and slurry scouring. Uneven wear will cause the roller gap to change and vibration to increase. It needs to be maintained by surfacing repair or overall replacement. The replacement cycle is long (about 2-3 years), but the maintenance cost is high.

Hydraulic system components (maintaining ultra-high working pressure, seals are prone to failure):

Hydraulic cylinder seals (piston seals, rod seals, etc.): They are very easy to age, tear or deform in 300MPa ultra-high pressure, vibration and dust environments, resulting in hydraulic oil leakage, unstable system pressure and even loss of pressure. They must be checked and replaced regularly (cycles are about 6-12 months).

Accumulator bladder: Used to absorb pressure fluctuations and shocks. It is easy to fatigue and rupture under high-frequency and high-pressure pulses. Nitrogen pressure and status need to be checked regularly, and the service life is about 1-2 years.

High-pressure oil pipe joint seal: It is subjected to ultra-high pressure and vibration shock, and it is easy to collapse and cause oil spray. It needs to be replaced immediately after inspection and leakage.

Hydraulic oil filter: It is very important! It filters metal debris and impurities in high-pressure oil to protect precision hydraulic components. It must be checked monthly and replaced every 3 months, otherwise it will accelerate the damage of expensive parts such as pumps and valves.

Bearing system (bearing huge impact loads, high risk of mineral powder intrusion):

Roller bearings (tapered roller bearings/spherical roller bearings): Support rollers and bear huge impact loads caused by ore particle size fluctuations (usually >50mm). Mineral powder intrusion seals or poor lubrication will significantly shorten the life, causing raceway peeling and cage fracture, which will manifest as vibration and abnormal temperature rise. Although the design life is long, the actual life is about 2-5 years under harsh mining conditions. It is a key spare part with high value and long procurement cycle.

Reducer bearings: Bear transmission torque and impact, and need to rely on good lubrication. The metal content of the lubricating oil needs to be monitored regularly.

Feeding and sealing components (facing ore scouring and extrusion):

Feeding device wear plate/liner: Guides ore into the roller gap and withstands the severe scouring and wear of high-speed ore flow. It is often necessary to weld hard surfaces or inlay ceramic wear blocks, and the replacement cycle is about 4-8 months.

Side baffle sealing strips and wear blocks: Installed at both ends of the roller to prevent ore from leaking from the side and bearing extrusion friction. The edge wear rate is very fast (up to 10mm/month), and the wear blocks need to be adjusted or replaced regularly.

Scraper device (cleaning adhered ore powder):

Scraper blade (hard alloy): Close to the roller surface, scrape off the adhered wet or fine ore powder. Wear shortens or fails under continuous high friction. Failure will cause ore powder to accumulate on the roller surface, affecting operating efficiency and roller surface life, and the replacement cycle is about 3-6 months.

Scraper blade holder: It may be deformed due to uneven force or ore jamming, and needs to be corrected regularly.

Transmission system components (transmit huge torque, compensate for installation errors):

Universal coupling cross shaft and bearings: Working under heavy load, impact and certain deflection angle, the cross shaft and needle bearing are vulnerable points. It is recommended to disassemble and inspect every year, and the assembly must be replaced every 2 years.

Reducer gear oil: Need to be tested and replaced regularly to maintain cleanliness and performance.

Lubrication system components (to ensure the normal operation of key friction pairs):

Bearing grease/lubricating oil: Need to be replenished and replaced according to the prescribed cycle.

Lubrication pipelines and joints: May be damaged and leaked due to vibration, external force or aging.

Lubrication pump/distribution valve: Mineral powder is easy to block the oil circuit, and it needs to be cleaned and maintained regularly and replaced when damaged.

Lubricating oil filter: Protect the lubrication point and need to be replaced regularly.

Seals (to prevent mineral powder intrusion and oil leakage):

Bearing seals (lip seals, labyrinth seals): Very important! Prevent mineral powder from invading the bearing cavity and lubricating oil leakage. The lips of contact seals are easily worn or aged by hard particles, and non-contact seals will also wear out. It is the key to the life of the bearing and needs to be replaced or updated regularly with the bearing overhaul.

Other static seals (O-rings, gaskets): The seals at the joints, flanges, pipe joints, etc. of the equipment need to be replaced after aging to prevent leakage.

Key factors affecting the replacement frequency of High pressure grinding rolls parts (more stringent than cement working conditions):

Ore characteristics: hardness (determinative), abrasiveness (especially quartz content), particle size distribution (large block impact), moisture (wet adhesion aggravates hardening and wear). The harder the ore, the higher the quartz content, the larger and more uneven the particle size, the faster the wear.

Equipment operating parameters: working pressure (the higher the pressure, the faster the wear), processing capacity, and operating hours. Pressure is the core factor.

Operation and maintenance: whether the feeding is stable and uniform, whether there are oversized pieces or metal foreign matter entering, whether the lubrication and oil management are in place (extremely important), whether the inspection is careful, and the installation quality.

Quality of parts: wear-resistant material grade (such as carbide grade), manufacturing process, heat treatment level.

System configuration: open circuit or closed circuit, cycle load size.

Summary:

The core of High pressure grinding rolls maintenance is to deal with the reliability of seals under extreme wear and ultra-high pressure. Roller nails, roller surface matrix, hydraulic seals (especially cylinder seals), bearings, scraper blades, feed wear plates, and side baffle wear blocks are the most frequently replaced parts. The harshness of mining conditions makes spare parts management and preventive maintenance more critical than in the cement industry. Establishing a predictive maintenance system based on oil analysis and vibration monitoring, as well as an accurate strategic inventory of key spare parts (considering long procurement cycles), is essential to ensure the continuous and stable operation of HPGR and control the overall cost. The specific replacement cycle must be dynamically adjusted based on the actual ore properties, operating data and maintenance experience.

High pressure grinding rolls spare parts inventory priority recommendations (based on mining conditions):

Extremely high priority (frequent replacement, must be always available): Carbide roller nails, scraper blades (carbide), hydraulic cylinder seal kits, hydraulic oil filter elements, lubricating oil filter elements, side baffle wear blocks, feed device wear plates/lining materials.

High priority (periodic replacement or prone to accidental damage): Universal coupling cross shaft assembly (including bearings), bearing seals (various types), accumulator bladders, high-pressure oil pipe joint seals, lubrication distribution valves.

Medium priority (long life or low damage rate, but large downtime impact/long procurement cycle): Roller surface wear lining/matrix (or surfacing material), roller bearings (strategic reserve!), reducer bearings, reducer gear oil (replaced as planned).

Low priority (long life or low damage rate): Large structural parts, hydraulic cylinders, reducer housings, motors, etc. (usually replaced during overhaul). However, key large bearings should have a certain strategic reserve.

High pressure grinding rolls parts produced by our company