Data from the Health and Safety Executive (HSE) shows that over 3,500 quarry workers have suffered an injury reportable to HSE since 2000, with 31 of those being fatal. There are several initiatives to improve safety in the sector, this includes Target Zero, a Quarries National Joint Advisory Committee (QNJAC) scheme that has helped to reduce quarry accidents by over 80 per cent since 2000.
While this invaluable scheme — which includes training conferences and the creation of informative material — has achieved great things for the industry, the most effective way to minimise human risks in quarrying is to remove them from the most dangerous aspects. Automation is key to achieve this.
Automated equipment is already widely used to perform drilling, blasting, loading, hauling and sorting of materials. In addition to increasing speed and accuracy in these processes, automation can remove the need for operators to work intimately with dangerous equipment.
However, one area that often requires human intervention is the unblocking of jaw crushers. By nature, a jaw crusher must be incredibly strong. Rock enters the crusher from the top of the machine and gets compressed between two surfaces — the fixed and moveable jaw. The rock will continue to be crushed until it is small enough to fall through the opening. Unfortunately, these crushers occasionally get blocked by the rocks and stones.
Naturally, prevention is better than cure. Every effort should be made by the quarry team to prevent blockages occurring, for instance: designing quarry blasts to achieve optimum rock fragmentation, reducing oversize material, and ensuring that filler buckets are appropriately sized for the capacity of the crusher. However, occasional blockages are still inevitable.
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In the past, operators have succumbed to dangerous methods of removing blocked stones. Questionable tactics include using a tooth on chain to get the jaw to bite — creating the possibility for the tooth to be ejected at high velocity. Or, using brute force with a jack hammer, sledgehammer or similar to break the stones or pry them from position. If you’ve ever seen a sling, give way in this situation, you’ll think twice about this method.
Technidrive had witnessed these risks firsthand and wanted to develop a system to remove human intervention in this dangerous job. The vision was an automated system that unblocks a crusher using mechanical forward and reversing actions to shift the stones. The system would sense when the blockage had been freed and give an automated signal to notify operators that the process was complete.
Technidrive developed its innovative jaw crusher unblock system in 2015, and it has since been deployed at quarries across Europe. The team began its design by carrying out torque and speed calculations to determine what drive system was needed. In addition to the motor, we needed a variable speed drive (VSD) that could control the speed and torque.
Crucially, the system could offer startup when starting the jaw crusher from full. To achieve this, the team developed its own innovative software which ensured the VSD could be remotely activated in unblock mode and operators would be kept out of harm’s way.
Since the initial development, Technidrive has created similar equipment for several other businesses in the quarrying industry. Treating each project on an individual basis, the organisation has been able to design, manufacture and deliver bespoke turnkey systems to a number of different sites.
When working alongside earth-moving equipment, removing operators from the most hazardous aspects should be a no brainer. While the quarrying industry will always be among the world’s most dangerous sectors, mechanical automation can play a crucial role in reducing risk and supporting the industry’s efforts towards Target Zero.
