The Herrenknecht Boxhole Backreaming Machine (BBR) bores and reams ore passes and ventilation shafts with diameters of up to 3.5 meters. Based on the proven BBM technology, the BBR is characterized by high efficiency and high safety standards. Upon request, Herrenknecht will supply the BBR with a project-specific lowering unit. With this, lining of the shaft can already be done parallel to the reaming operation, saving time and increasing safety.
Proven technology – advanced for new challenges
The design and working principle of the Boxhole Backreaming Machine (BBR) are based on the proven technology of the Boxhole Boring Machine (BBM). A boring unit at the head of the pipe string is pressed upward from the launch point. Additional thrust pipes are installed one after the other and pushed forward, thus increasing the drilling length.
The boring process
The cutterhead excavates rock with compressive strengths of up to 300 MPa and with a borehole diameter of up to 1.5 meters. The excavated cuttings fall through the center of the boring unit due to the force of gravity. The cuttings are transferred to a muck chute at the jacking frame via channels introduced into the thrust pipes. After each jacking stroke, the boring process is stopped for a short time to secure the pipe string and the boring unit. Then the next thrust pipe can be installed in the jacking frame.
All production steps of the Herrenknecht BBR are remotely controlled. No personnel needs to be in hazardous areas during operation. Therefore, work safety is improved significantly.
The reaming process
After breaking through to the upper level, the cutterhead is removed and replaced by the reaming head. The reaming head expands the bored hole to diameters of up to 3.5 meters. The modularity of the reaming head offers the possibility of adapting the diameter to individual requirements. Coordinated with the progress of the reaming, the thrust pipes are removed by the jacking frame one by one until the reaming head breaks through to the lower level. A pipe handler provides mechanized handling of the thrust pipe and thus improves work safety.
The compact and reliable hydraulic main drive of the Herrenknecht BBR increases the efficiency of both the boring and the reaming processes.
Conventionally, a shaft is secured after the reaming process has been completed. This is time-consuming and poses the risk that the excavated shaft collapses partially before it is secured and requires rework.
Herrenknecht optionally offers a newly developed lowering unit for the Boxhole Backreaming Machine for time-saving simultaneous lining of the shaft. The lowering unit is installed on the upper level after the breakthrough of the cutterhead and the assembly of the reaming head. The lowering unit inserts steel lining segments, one after the other, into the shaft following the progress of the reaming head. Thus, the shaft is completely lined and secured when the reaming head reaches the lower level.
The lowering unit is operated by remote control as well to improve work safety.
The BBR can be moved between locations quickly and independently on its own crawler unit.
Proven technology meets innovative solutions
The newly developed boxhole backreaming technology is the right choice for the fast and economical creation of ore passes and ventilation shafts. The innovative combination with an optional lowering unit allows shaft lining simultaneously with the reaming process. This method offers mines a safer and quicker development of the orebody and thus an earlier start to production.