Solid column explosive charge method for blasting rock

Abstract

A solid column explosive charge method for blasting rock includes a hollow gas-filled core component arranged collinearly in concentrically spaced relation within a vertical borehole, the core component being seated upon a first layer of particulate explosive material, and a first annular portion of the particulate explosive material being arranged concentrically about the core component. The first layer and the first annular portion are in engagement to define a continuous explosive column. A plurality of core components together with associated layers and annular portions of the explosive charge may be arranged in a continuous vertical column, the total volume of the core components being from 10 percent to 25 percent of the volume of the explosive column. A top layer of inert fill material is arranged above the core component to close the upper end of the bore opening.

1 . A method for blasting rock for surface coal mining and the like, comprising: 
 (a) drilling in the rock a vertical bore hole having a given diameter and a generally vertical axis;    (b) depositing into said bore hole a bottom layer of inert backfill material;    (c) depositing into said bore bole above said layer of backfill material a first layer of a particulate explosive charge;    (d) inserting into said bore hole in seated engagement with said first explosive layer a first hollow gas-filled core component having a longitudinal axis collinear with said bore hole axis, said core component having a cross-sectional dimension that is less than that of said bore hole diameter;    (e) depositing into said bore hole concentrically about the entire length of said core component a first annular portion of said particulate explosive charge, said first annular explosive portion being in direct engagement with said first layer, thereby to define a continuous explosive column containing said core component, the volume of said core component being about 10 percent to 25 percent of the volume of said continuous explosive column;    (f) depositing into said bore hole above said core component a top stem of inert material; and    (g) detonating said particulate explosive charge.    
     
     
         2 . A method for blasting rock as defined in  claim 1 , and further including, prior to said top stem depositing step: 
 (h) depositing in said bore hole above said first annular explosive portion a second layer of said particulate explosive charge;    (i) inserting into said bore hole a second hollow gas-filled core component having a longitudinal axis collinear with said bore hole axis, said second core component having a cross-sectional transverse dimension that is less than said bore hole diameter; and    (j) depositing into said bore hole concentrically about said second core component a second annular portion of said particulate explosive charge, said second annular explosive portion being in engagement with said second layer, and said second layer being in engagement with said first annular portion, thereby to define a continuous explosive column containing said core components in spaced collinearly arranged relation, the sum of the volumes of said core components being 10 percent to 25 percent of that of said continuous explosive column    
     
     
         3 . A method for blasting rock as defined in  claim 2 , and further including: 
 (k) depositing into said bore hole above said second core component and in direct contact with said second annular explosive portion a third layer of said particulate explosive charge, thereby to define a continuous explosive column between said first and said third explosive layers.    
     
     
         4 . A method for blasting rock as defined in  claim 2 , and further including 
 (k) introducing into said first layer a booster firing cap for detonating said continuous explosive column.    
     
     
         5 . A method for blasting rock as defined in  claim 2 , wherein each of said core components comprises a cylinder having a circular cross section.  
     
     
         6 . A method for blasting rock as defined in  claim 5 , wherein said core component is formed from a heat sealable synthetic plastic material having a thickness of from about 1.2 to 10.0 millimeters.  
     
     
         7 . A method for blasting rock as defined in  claim 6 , wherein said synthetic plastic material is provided in continuous tubular form, and further including: 
 (l) transversely heat sealing a length of the tubular synthetic plastic material at one end to define a first transverse seam;    (m) heat sealing the other end of said plastic material length to partially close the same and to define a second transverse seam containing a filling opening;    (n) introducing compressed air into said severed length via said filling opening;    (o) closing said filling opening; and    (p) placing the inflated core component in the borehole.    
     
     
         8 . A method for blasting rock as defined in  claim 7 , wherein said bore hole has a diameter of from about 6″ to about 13″.  
     
     
         9 . A method for blasting rock as defined in  claim 8 , wherein said bore hole has a depth of from about 10 feet to about 200 feet.  
     
     
         10 . A method for blasting rock as defined in  claim 9 , wherein said core component has a length of from between 3 feet to 6 feet.  
     
     
         11 . A method for blasting rock as defined in  claim 5 , wherein said cylindrical core component is formed from paperboard.  
     
     
         12 . A method for blasting rock as defined in  claim 1 , wherein said core component is formed from a cardboard blank having panels and flaps that are folded to define a closed air-filled container.