1. Working Conditions
Strongly Weathered Limestone: long-term weathering product, gray-yellow to yellow-brown, loose porous surface, densely developed joints and fractures. Hardness 30-55MPa, medium-hard to hard rock. Despite weathering, high CaCO3 cementation maintains considerable bearing capacity.
Separate-arm ripper (J Series) is recommended for medium-hard to hard rock. Split structure provides concentrated breaking force and strong penetration, specifically designed for hardness above 30MPa.
 
2. Recommended Equipment
Model
Excavator Tonnage
Hardness Range
Application
Core Advantages
CSJ700J
65-85t
30-38MPa
Medium-hardness weathered layer
Concentrated breaking force, high efficiency, best cost-performance
CSJ900J
85-95t
35-45MPa
Higher hardness weathered layer, large faces
Strong penetration, large radius, suitable for large faces
CSJ1200J
120t
40-55MPa
High-hardness weathered layer, super large faces
Extra-large breaking force, highest single-shift output, hard rock preferred
 
 
3. Production Rate
Rock Hardness
CSJ700J (65-85t)
CSJ900J (85-95t)
CSJ1200J (120t)
30-38MPa
120-160m³/h
140-200m³/h
180-240m³/h
35-45MPa
—
130-180m³/h
160-220m³/h
40-50MPa
—
100-150m³/h
140-200m³/h
45-55MPa
—
—
120-170m³/h
 
Reference data from Separate-arm ripper field tests. Despite weathering, CaCO3 cementation maintains 30-55MPa; J Series required.
 
4. Construction Process
· Geological Survey: Weathering degree varies; conduct multi-point sampling to assess hardness, fracture density, and rock orientation of each layer
· Equipment Selection: Select CSJ700J for 30-38MPa, CSJ900J for 35-45MPa, CSJ1200J for 45MPa and above based on test hardness
· Equipment Mobilization: Position Separate-arm ripper, inspect hydraulic system, pins, and safety devices
· Layered Stripping: Strip from top to bottom along bedding, control layer thickness 300-500mm; utilize joints and fractures to reduce breaking resistance
· Breaking & Screening: Screen through vibrating screen, control product size ≤350mm; separate stone and soil for stacking
· Slope Trimming: Use Separate-arm ripper for slope trimming, control slope angle for long-term stability of mining face
 
5. Efficiency Comparison
Item
Traditional Blasting

Daily Output (8h shift)
600-1200m³

Safety
High risk (flying rocks, vibration, long approval cycle)

Comprehensive Cost
Explosives + detonators + permits + safety + labor

Size Control
Poor (over-blasting, uneven particle size)

Environmental Compliance
Requires approval, heavy pollution

 
 
6. Construction Precautions
· Equipment Selection is Core: Hardness 30-55MPa mandates Separate-arm ripper (J Series)! Mono-arm ripper (C Series) cannot handle this!
· Utilize Joints & Fractures: Dense joints reduce breaking resistance; break along fracture directions to significantly improve efficiency
· Hardness Zoning: Weathering layer hardness varies; conduct multi-point sampling before construction to avoid incorrect model selection
· Equipment Maintenance: Separate-arm ripper wears significantly on hard rock; check drill rod and tooth tip wear each shift, replace promptly
· Working Face Management: Keep face flat and orderly, clear debris promptly for smooth equipment movement and improved efficiency