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What is the VCR method? What are the characteristics of VCR blasting?
The VCR method is the abbreviation of the term "Vertical Crater Retreat". Its essence is to drill large diameter deep holes to the lower cutting lanes at a certain pitch and row distance in the upper cutting lane. When the mine collapses, the length from the top platform is not larger than the diameter. 6 times the drug pack, then a certain thickness of ore is broken down from the bottom to the top along the full length and full width of the stope, and the entire mining height is finished layer by layer. Thus, the lower cutting lane becomes a mining roadway. See Figure 1.
Figure 1 Schematic diagram of stope layout and mining project
The main feature of this method is that the two ends of the direct blasthole are open, requiring special equipment to hold the medicine pack at a predetermined position, so charging is a very critical operation of this blasting method. When the spherical drug pack is embedded in the free floor of the stope floor, the free space blasting, that is, the inverted funnel blasting, is a feature of the VCR method.
The VCR method is mainly used for vertical ore bodies with a medium or thick thickness, steep slopes with an inclination angle greater than 60°, and small ore blocks with an inclination angle greater than 60°.