1 Introduction
2 Comparison of Different Mining Methods
Criterion | Compared to drilling and blasting | Compared to partial-face excavation |
---|---|---|
Safety | Higher safety | Generally safer a |
Production rate | Higher production/excavation rates in favorable ground conditions (higher economic benefits/saving money, early mining of high-grade ore, earlier job completion) | |
Selective excavation | Not suitable (partial-face enjoys minimum ore dilution/minimum mixing with gang, increased ore recovery, separate excavation of rock layers in different strengths making excavation easier) | |
Muck or mineral fragmentation quality and haulage | Uniform muck size (easy muck/excavated material haulage, no secondary breakage of large rock chunks, lower crushing and mineral processing costs) | Equivalentb |
Continuity of operation | Continuous operation (not periodic, conducive to automation, excavation-loading-ground supporting simultaneously) | Equivalentc |
Cuttable ground types | Not applicable in very hard and abrasive rocks | Wider range of rock strength compared to partial-face |
Ground disturbance | Less overbreak, less scaling-support requirement, minimized support maintenance, superior ground control in jointed/broken rocksd | Equivalent |
Environment adaptability | More environment-friendly operation (no blast vibrations, no blasting ventilation required) | Equivalent |
Flexibility | Less flexibility on working conditions, very sensitive to ground conditions, Limited opening cross-section area and shapes and usually not able to cut low turnoff radii, especially compared to roadheaders, Difficult adaptability to a working mine design | |
Mobility | Very large and heavy machines with low mobility from one face to anothere | |
Maintenance | In hard and abrasive rocks, frequent maintenance of the machine might be necessary | Less accessibility to the cutterhead face and harder maintenance operation |
Capital cost | Higher initial/capital cost | Equivalent or higher depending on the conditions |
3 Current Technologies of Small Diameter Full-face Machines
3.1 Pipe Jacking Machine
3.2 Boxhole Boring Machine (BBM)
3.3 A Technical Comparison Based on Performance Parameters
Model | Excavation diameter (mm) | Outer diameter of concrete pipe (mm) | Recommended drive length (m) |
---|---|---|---|
AVN800XC | 975 | 961 | 150 |
BBM1100 | 1100 | – | 30 |
Machine Type | Thrust (kN) | Torque (kNm) | N (rpm) | P (kW) | Penetration per revolution (mm/rev) | NPR (m3/h) | SEopt (kWh/m3) |
---|---|---|---|---|---|---|---|
BBM1100 | 1200 | 31.68 | 29 | 96.2 | 0.9 | 1.12 | 68.8 |
Pipe jacking (1100 mm)a | 1005 | 29.3 | 7.4 | 22.7 | 3 | 0.95 | 19.1 |
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BBM1100 dimension (l/w/h): 7.6 m/2.5 m/3.3 m, the crawler dimension: 6.25 m/2.52 m/1.61 m
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AVN 800 XC: Outer diameter: 975 mm, Length articulation shield: 2.4 m, Length machine can: 2.2 m