1 - Introduction
Stemming is a key element in the drill and blast process. Is used in order that a high-explosive charge works properly and releases the maximum energy. It also allows the control of airblast and flyrock. Normally, the material used on stemming is drill cuttings.
Fig. 1 – O-Pitblast Borehole information (Stemming)
2 - Objectives
The main objective that O-Pitblast wanted to overcome was relative to safety. The reduction of flyrock and of the exclusion zone were the main objectives. Also, the improvement of explosive energy was a proposal to be treated during all the process.
Fig. 2 – Problem identification
3 - Proposed solution
The process evolved some improvements to be applied during the weeks that O-Pitblast was on the field.
Three main procedures were taken:
• Theoretical Training;
• Field Practices;
• Field Control with O-PitApp.
The use of the App allowed to control the loading, identify re-drills, identify cavities, recognize operations issues and potential flyrocks.
4 - Client gains
4.1 - Main gains
After the application of the solution proposed by O-Pitblast the client could reduce the flyrock, as shown in the pictures below.
Fig. 3 - Blast comparison: after O-Pitblast solution (on the left) and before O-Pitblast solution (on the right)
It also provided that the engineers had access to loading information before the blast, clearance of the adjustment zone and improvement on stemming control.
4.1 - Economic gains
Speaking on economic terms, the client could reduce costs on the operation like specified below.
Reduction of Boulders:
• Avg. 10 boulders/month;
• More than 1.500,00 $ per year;
• 3kg per hole = 10 cm extra charge length = 3,00 $
• 7000 holes per month = 84 000 holes per year = 252.000,000 $