Powder factor prediction in blasting operation using rock geo-mechanical properties and geometric parameters

Abstract

Prediction of powder factor is a major activity while preparing drilling and blasting operation, as the total production cost depends on it. It is a major input parameter in blast design as it influences the efficiency of subsequent operations in mining. Generally, effective parameters that influence powder factor can be divided into three, namely, rock mass, geometric and explosive parameters. In this study, the rock mass properties and geometric parameters were studied based on the ratio of the mass of explosive and blast design. The main objective of this study is the application of rock engineering system (RES) to calculate the powder factor index (Pfi) based on predominant rock mass properties and geometric parameters. This approach was applied to a database of twenty-four blast sites comprising of rock mass rating, blastability index, porosity, specific gravity, uniaxial compressive strength, the burden, the ratio of space to the burden, the ratio of drilled-hole depth to burden, drilled-hole diameter and the ratio of the burden to drill-hole diameter. The relationship between these parameters and how each of them influence powder factor was studied and used to predict powder factor index. The result shows that rock mass rating, blastability index, porosity, specific gravity, uniaxial compressive strength and drilled-hole diameter affect powder factor. It also shows that Pfi is a robust technique for generating an improved line of fit and predicting more dependable and accurate valuation of powder factor with the coefficient of determination (R2) of 0.86, and root mean square error (RMSE) of 0.023 when compared with the traditional multivariable regression method.

Keywords

• blasting
• burden
• powder factor index
• rock engineering system
• rock mass rating