Shotcrete Equipment Choices EAGCG - Shotcrete Workshop 18-19 May 2017 John Gelson Australian Shotcrete Society
Introduction The presentation will focus solely on the wet shotcrete robotic equipment side However we need to always be mindful of the total shotcrete process. This total process is a holistic approach to any shotcrete operation.
Some Mining Parameters to consider - The mine development plan The shotcrete ground support plan Total number of headings Batch plant size, type & requirements Decline or Shaft. (Grade and depth) Roadway dimensions Concrete truck size and numbers Tramming distances Suitable shotcrete sprayer numbers Equipment support Costs overall taken over time
Shotcrete Transportation - Vertical: Boreholes / Slicklines Shaft Mines
Shotcrete Transportion - Declines and horizontal transport: Transmixers / Agitators
Transmixers and Agitators Capacity matched to heading size/multiple headings Drum design For limited height For batching or remixing shotcrete (agitator type) Brakes mine design vehicle Local mining guides / codes Axles matched to full payload Articulation for tight turns Discharge to sprayer
Application: the Business End of the Process Shotcrete : Mix Design Design/Chemicals/Manufacture Surface Transport Vertical Logistics: Borehole, Slickline or Ramp Underground reception Transportation: Agitators, Transmixers Sprayer + Operator Equipment selection Pump filling rate Low pulsation Integrated accelerator dosing Lighting Maneuverability, reach Operator training Consistency / Reliability In-situ Sprayed Shotcrete
Sprayers many makes, and not all are equal!
Sprayers Mining Equipment key features Robustness heavy duty carrier Working height & manoeuvrability Diesel or Electric Spraying capacity On board compressor? Minimal pulsation pump Tramming capability Ease of operation and spare parts Non-corrosive accelerator tank Pump hopper synched to transmixer Integrated accelerator dosing system Boom stability Pressure cleaner / oiler High pressure scaling Lighting!
Pulsation results in layering weaknesses Layering, neat accelerator
Optimized shotcrete pump operation and the importance of high slump Standard pump Shotcrete flow Accelerator flow Optimised pump Low pulsation concrete pumping Continuous flow accelerator pumping Good workability of shotcrete / concrete High slump shotcrete To give best piston fill 11
How to see layering during the spraying process Thermal imaging can be used to see the flow of shotcrete and accelerator during spraying. From the thermal videos, particularly with the pumps that provide more interruption in concrete flow, the darker blue/purple from the nozzle is pure accelerator. This hits the concrete surface and makes it go bright yellow immediately causing a surge in the heat of hydration due to accelerator overdosing of the concrete surface. This would cause a hardened substrate surface for the overlying shotcrete. Net result is poor bonding layering of incomplete shotcrete. NorStreamer low pulsation pump "Standard" sprayed concrete pump
Accelerator Dosing System
Sprayer - Operation Safety assessment of ground Correct sprayer positioning Nozzle distance and orientation Substrate preparation Correct air pressure Correct lighting Secure operator vantage point (from supported ground) Cable or radio remote Maneuverability Experience and operator capability Ease of operation Simple cleaning Controlled use of accelerator Take your time 12-15m3 /hr
Shotcrete machine monitoring Accelerator usage Concrete temperature Ambient temperature Accelerator temperature Shotcrete pump speed Shotcrete pump hydraulic pressure Shotcrete (m3) used last shift Accelerator (L) used last shift
Equipment Supplier Support What are the needs! Commissioning of new equipment Maintenance and operator training OEM spare parts availability OEM service & technical support availability Overhaul and rebuild facilities Preventive maintenance Knowledgeable support personnel Rapid response and availability of trained technicians Supplier who understands the shotcrete process is variable
Shotcrete for the Future Thickness control Consistent remote control Increased automation New fibre types Tier 4 Diesel Engines Electric/Battery power Alternative materials
The underground space becomes connected Visualization & Data analysis Data Mule Data logging Sprayed concrete UG Wireless Access point Data logging Laser scanning
Thanks for your attention
Back Up Slides
An Agitator can batch shotcrete A Transmixer transports shotcrete
The importance of High Slump for Minimized Pulsation High pulsation 1 Low workability Accelerator concrete Concrete output versus accelerator 2 Accelerator concrete High workability Low pulsation
Laser scanning of shotcrete layer thickness WORKFLOW: 1. Reference scan 2. Shotcrete applied 3. Second scan 4. Resulting thickness is calculated in near real time 5. Result is visualized Improved documentation, improved quality, improved safety
Debunking Shotcrete Myths Shotcrete is expensive vs. bolts and mesh You can t drop shotcrete more than 750m Shotcrete isn t ductile Mesh is better than fibres Process knowledge is critical!
Elements of Shotcreting Design Materials Manufacturing Logistics Application Performance & QA/QC Support 27
Nozzle Set-Up, Air Supply Air hose Air hose size Accelerator hose Proper mixing Nozzle Nozzle tip Concrete hose Accelerator hose Minimum requirements for compressor: minimum capacity of 10 12 m 3 /minute pressure of minimum 6 7 bars
What Normet has done? Development of own concrete spraying pump, NSP 30 &40 Intensive testing prior production Several development versions Sophisticated control and adjusting system of concrete pump Accurate accelerator dosing system with stable flow and pressure 29