Laserfiche WebLink
Production patterns will vary in burden and spacing dimensions. Burden spacing will range from 6 <br />to 25 plus feet. Spacing will vary from 6 to 25 plus feet. Burden and spacing dimensions are <br />governed on drill bit size (5.25 to 7 inch diameter), hardness of rock and degree of fragmentation <br />desired. Normal production blasting will be a rectangular pattern with on-echelon delays. <br />Staggered patterns have been used in the past with success and will be used in the future as <br />conditions warrant. Stemming will be washed gravel to contain the pressures. Typically, six to <br />eight holes per row and six to twenty rows per shot will be used. Smaller or larger patterns may <br />be used or tried to make the shot mare economical or to fragment the overburden better. <br />Standard on-echelon delay sequencing in normal production shots will use appropriate delays in <br />order not to exceed the peak particle velocity of 1 inch per second. WFC will vary from this <br />design some what to reduce ground vibrations and increase fragmentation. <br />Normal production blasting breaks to two faces and delays will all be non-electric. Non-electric <br />delays will be located on the surface and down each borehole to minimize the number of holes <br />• detonating in any given 8ms time period. Use of non-electric delays reduces noise and increases <br />safety in a region of frequent thunderstorms. <br />A typical production, decked production and parting blast design can be examined in Attachment <br />2.05.3(6)(a)-5. These blast designs have been approved by a certified blaster. <br />Explosive Selection and Poundage <br />Actual field experience at the New Horizon Mine indicates a high percentage of the blast-holes <br />contain some amount of water. Since the startup of the mine, various water resistant products <br />and loading techniques have been examined and tried. New Horizon Mine has settled upon the <br />use of: a) water resistant slurry for the extremely wet holes, b) bagged gel products in conjunction <br />with ANFO in plastic sleeved holes for slightly wet holes, c) de-watering pumping of the wet holes <br />• (Revised 12-07-99) 2.05.3(6)(a) 5 <br />