1. Analysis of Copper Mine Operating Conditions
Copper ore has a Mohs hardness of 3.5–4.5 and is highly corrosive, placing demanding requirements on the impact resistance and corrosion resistance of belt cleaners. Conveyor belt speeds range from 5.8 to 6.5 m/s, with throughputs of 6,000–11,000 t/h; single conveyor lengths often exceed 5 km, and operating altitudes can reach up to 6,000 meters. Incorrect cleaner selection will seriously compromise cleaning effectiveness and service life.
UV radiation intensity is 1.5 times that at sea level; the diurnal temperature range can reach 40°C; the air is dry with high dust concentrations. These conditions impose higher demands on the aging resistance of polyurethane and rubber components.
2. Analysis of Common Cleaner Failure Causes
• Standard polyurethane (PU) blades typically last fewer than 500 hours under high-speed belt friction, with a wear rate exceeding 0.1 mm/hour.
• Blades frequently sustain root cracks from repeated high-impact collisions with large ore chunks, eventually leading to tearing.
• Blade elasticity degrades due to accelerated aging from UV and ozone exposure, preventing tight belt contact and causing residual material buildup. Hard or improperly adjusted alloy blades cause abnormal wear on belt cover rubber at depths of up to 1–2 mm per year.
• High belt-speed friction requires frequent re-tensioning. If adjustments are delayed, material spillage occurs and fine debris accumulates between blade and belt, severely impacting cleaning effectiveness even after re-adjustment.
3. Blade Selection for Belt Cleaners
A. Primary (1st Stage) Cleaner Blades
Blades should be made of ultra-high wear-resistant polyurethane, with a recommended hardness of 90–95 Shore A and an Akron abrasion value of ≤ 0.03 cm³/1.61 km.
Blade height and volume should be matched to pulley diameter:
• Pulley diameter 800–1,200 mm → blade height ≥ 260 mm
• Pulley diameter 1,000–1,400 mm → blade height ≥ 380 mm
• Pulley diameter > 1,400 mm → blade height ≥ 500 mm
Polyurethane hardness should be neither too soft nor too hard. Excessively soft blades suffer poor wear resistance and shortened service life; excessively hard blades lose rebound elasticity, creating a risk of cracking or breaking when the belt surface is uneven.
Primary cleaners must be equipped with a heavy-duty spring or pre-tensioned automatic tensioning system capable of automatically compensating for wear and belt bounce, maintaining constant pressure. The spring assembly should provide continuous, adjustable pressure of 140–180 N.
A fully automatic tensioning system delivers continuous, constant pressure to the blade, eliminating spillage caused by delayed manual adjustment. It should also provide a blade wear alert, helping maintenance personnel assess whether the blade can safely operate through the next production cycle — reducing replacement costs and spillage risk.
When belt speed ≥ 3.5 m/s or cover rubber thickness ≤ 5 mm, alloy tip blades are not recommended for primary cleaners. The frictional heat generated at high speeds accelerates aging of the belt cover rubber.
B. Intermediate Stage Cleaners
For dry raw copper ore:
It is recommended to add an air knife cleaner before the secondary cleaner. High-velocity air curtains strip away fine dust for contact-free cleaning. Combined with a high-efficiency dust collector, airborne dust can be channeled back into the material flow, supporting clean production. This is particularly suited to applications with strict belt protection requirements and dry material conditions.
For wet flotation copper concentrate or slurry:
It is recommended to add a spray cleaner before the secondary cleaner. This effectively softens sticky bulk material and flushes the belt surface, providing necessary preparation for effective secondary cleaning.
C. Secondary (2nd Stage) Cleaner Blades
Blades should be alloy type supported by an elastomeric backing. The carbide should meet ISO K20–K30 grade (e.g., YG8 grade), with Rockwell hardness HRA ≥ 89 for superior wear performance.
The elastomer should have a Shore A hardness of 80–85A, improving alloy tip conformity to the belt while maintaining rebound elasticity. Tensile strength of the elastomer should be ≥ 25 MPa to prevent fracture under belt impact forces.
The blade should be installed at 90° to the belt surface to produce a “scraping” action rather than a “cutting” action.
Blade pressure settings:
• Dry raw copper ore: pressure set at 15–20 N/cm
• Wet flotation copper concentrate: pressure increased to 25–30 N/cm to enhance scraping force
• Higher belt speeds: moderate pressure increase to maintain cleaning effectiveness, while monitoring frictional heat
• New or high-strength belts (e.g., ST type): can withstand slightly higher pressure; worn or standard fabric belts (e.g., EP type): use lower pressure
4. Additional Brush Cleaners
For conditions involving poor belt surface flatness (aging belt, surface scratches, pitting), a brush cleaner is recommended after the secondary cleaner to clean recessed areas on the belt surface. The brush should rotate in reverse at a ratio of 1:10, using bristle diameters ≥ 2.5 mm, and should be equipped with a material deflector plate.
5. Summary
For belt cleaners designed for copper mining conditions, the starting point must always be the characteristics of the bulk material and the conveyor parameters. Cleaners should continuously evolve toward three goals:
• Cleaning effectiveness
• Service life
• Maintenance-free operation
Multiple targeted polyurethane and alloy blade materials should be provided based on belt speed, wet/dry material characteristics, and operating hours. Fully automatic locking systems, unmanned maintenance, and intelligent monitoring represent the direction of ongoing development.
