More modern approaches to spacing and blast design dramatically improve performance of blasts
By Anthony Konya, M.S., and Cal Konya, Ph.D.
Since the first application of black powder for blasting in 1627, blasters and engineers have been using powder factor as a design tool. Powder factor is the ratio of pounds of explosive used in a blast to the total volume of rock blasted; a typical range for surface blasting is 1.0 to 2.0 pounds per cubic yard (lb/yd3).
During the first few centuries of blasting the thought process was that each rock, depending on type and structural geology, had a specific powder factor that when achieved would give optimal fragmentation. After equations were developed to determine burdens, the blaster could then isolate the powder factor as the key performance indicator and adjust the spacing to achieve the proper value