1. Working Conditions
Calcareous Shale is rich in calcium carbonate (CaCO3), gray-white to light gray, hardness 30-45MPa, medium-hard to hard rock. CaCO3 content typically 15%-40%, reaching 50%+ in high-calcium sections.
Due to high hardness, traditional blasting is costly and blasting vibration can damage surrounding rock layers, affecting overall mining face stability.
For calcareous shale with hardness above 30MPa, the Separate-arm ripper (J Series) must be used for efficient breaking. The Mono-arm ripper (C Series) suffers severe wear at 30MPa+ and is not recommended.
 
2. Recommended Equipment
Model
Excavator Tonnage
Hardness Range
Core Advantages
CSJ400J
40-65t
30-35MPa
Concentrated breaking force, narrow working faces
CSJ700J
65-85t
32-38MPa
High output, hard rock preferred
CSJ900J
85-95t
35-42MPa
Strong penetration, heavy hard rock preferred
CSJ1200J
120t
38-50MPa
Extra-large breaking force, highest single-shift output
 
 
3. Production Rate
Rock Hardness
CSJ400J (40-65t)
CSJ700J (65-85t)
CSJ900J (85-95t)
CSJ1200J (120t)
30-35MPa
100-160m³/h
140-180m³/h
160-220m³/h
200-260m³/h
32-38MPa
—
120-160m³/h
140-200m³/h
180-240m³/h
35-42MPa
—
—
130-180m³/h
160-220m³/h
38-45MPa
—
—
100-150m³/h
140-200m³/h
 
Reference data from Separate-arm ripper field tests. Calcareous shale hardness ≥30MPa; Separate-arm ripper (J Series) is mandatory.
 
4. Construction Process
· Geological Survey: Confirm layer thickness, hardness distribution, and CaCO3 content; conduct multi-point sampling and testing
· Equipment Selection: Hardness ≥30MPa mandates Separate-arm ripper (J Series); Mono-arm ripper (C Series) is not suitable
· 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 for downstream processing
· Slope Trimming: Use Separate-arm ripper for slope trimming to ensure stable and regular mining face
 
5. Efficiency Comparison
Item
Traditional Blasting

Daily Output (8h shift)
600-1200m³

Comprehensive Cost
Explosives + detonators + permits + safety + labor

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

Impact on Rock Layer
Damages bedding, over-crushing, large CaCO3 loss

Environmental Compliance
Requires environmental approval, heavy pollution

 
 
6. Construction Precautions
· Equipment Selection is Key: Hardness ≥30MPa, Separate-arm ripper (J Series) is mandatory! Mono-arm ripper (C Series) cannot handle this!
· Hardness Zoning: Calcareous shale hardness distribution may be uneven; conduct multi-point sampling before construction
· Equipment Maintenance: Separate-arm ripper wears significantly on hard rock; check drill rod and tooth tip wear each shift, replace promptly
· Hydraulic System: High hardness creates high pressure on hydraulic system; use anti-wear hydraulic oil, shorten oil change interval (every 250h)
· Working Face Management: Keep face flat and orderly, clear debris promptly for smooth equipment movement