Introduction of drill and blast utilizing pneumatic rock-drills in a Rwandan artisanal underground mine
Journal of the Southern African Institute of Mining and Metallurgy
Rockbreaking accounts for 60% of the direct mining costs in small-scale mining. When drilling and blasting practices are poorly implemented the process becomes inefficient and dangerous. The introduction of a proven drill and blast system to artisanal mining offers a number of challenges, with safety being considered the backbone of any sustainable operation and a standard that cannot be compromised. The paper is based on a project at an artisanal cassiterite (tin) mining operation in a small
... ration in a small village in the Kayonza District in the Eastern Province of Rwanda. A drill and blast programme utilizing industry best practice was introduced at an underground development end; a raise developed at an inclination of 23 degrees. The underground working is accessed via a 17 degree incline shaft with an operating length of 105 m and serviced by a single drum winder. The winder operates at a speed of about 3.5 m/min hoisting two 1 t wagons from the bottom of the incline to surface for tipping ( Figure 1) . The drill and blast programme was implemented over a three-week period. As part of the work, a number of drilling patterns and cuts were investigated and a recommended pattern for the 1.2 m by 1.5 m raise was established. As part of the implementation process a time study was conducted of the development-related work cycle from the entry examination to the initiation of the development end. The challenges that arose with dry drilling in the schist and mica-quartz rock, as well as the issues of dust and ventilation, are discussed. The paper highlights the challenges and importance of the use of direction and grade lines, proper blast-hole marking and drilling, and the use of the burn cut. As part of the implementation programme, the actual cost of development was established, thereby allowing future mine rockbreaking, drill and blast cycle, drilling pattern, blast timing, misfires, artisanal mining.