For the excavation of vertical and inclined slot holes in underground mines, Herrenknecht developed the Boxhole Boring Machine (BBM) in 2011. It drills faster, safer and more economically than previous methods and equipment.In 2011 the BBM prototype was tested. Three years later, five BBMs were successfully operating in mines in Australia and Chile. Due to the industry demand and the need for such equipment, Herrenknecht is currently developing more BBM types.
There are two models, the BBM1100 which came first and has seen much success in Australian mines, followed by the BBM1500. For the drilling of ventilation shafts in the world’s largest underground copper mine, El Teniente in the Chilean Andes at 2,000 m above sea level, in 2013 Herrenknecht supplied one BBM1500 each to the drilling companies Gardilcic Ltda and Mas Errazuriz Ltda. The BBM1500 is a further development of the BBM1100 with a larger drilling diameter (1.5 m) and greater torque (135 kNm). In the course of developing the BBM1500, efforts were made to standardise as many assemblies as possible across the BBM1100 and BBM1500 types. In only a year from July 2013, over 30 slot holes were drilled by the two BBM1500s which excavated a total of around 1,200 m. Best performances of up to 2.7 m per hour and 17 m per day were achieved. The maximum distance excavated was 60 m.
In addition, a next generation BBM1500 was developed and manufactured by the end of 2015. It incorporates technical improvements to further optimise excavation activities. The drilling capacity was raised to drill holes up to 70 m. Furthermore, the machine’s dimensions were reduced to increase its mobility and flexibility.
The BBM technology is based on the proven principle of mechanised pipe jacking. The boring unit at the head of the pipe string is pressed forward from the starting point. More thrust pipes are successively installed and pushed forward into the pipe string, moving the cutterhead further into the geology. The length of the advance increases accordingly. The BBM can be used in hard rock formations. It allows diameters of up to 1.5 m with a maximum boring length of 70 m and an inclination of up to ±30° from vertical.