Conveyor Brake Control
Optimisation for Underground Coal Mine
Above: Receiving conveyor grossly overloaded on restart
The existing underground coal trunk conveyor was running on longer than the design stopping time, despite operating at only 78% of the design capacity of 4500tph.
This resulted in overloading and spillage on the receiving conveyor during restart. The client approached NEPEAN Conveyors to investigate and provide recommendations.
Changes to the proposed mine layout were also to be considered, in addition to the planned Longwall move, which would affect timing and duration of any shutdown required to implement changes to the conveyor braking system.
NEPEAN Conveyors reviewed existing trunk conveyor SCADA data of overrun events, then used this data to verify results of conveyor analysis using Belt Analyst™ and Dynamic Analyst™ software.
This indicated the brakes were adequately rated, and a further site investigation was conducted to capture additional test data, direct observation and review the current PLC control code and adjustment procedures, and the operational spare brake was returned to NEPEAN for testing.
It was found that the brake actuator adjustment procedure was resulting in a 30-45% reduction in available brake torque. Further conveyor analysis revealed a series of progressive changes to the winch control and brake location required to ensure stopping times could be achieved as the longwall maingate loadstation moved toward the tail end of the conveyor, resulting in higher brake torque demand.
Following the NEPEAN Conveyors recommendations, the client successfully completed the change management process and adjusted the brakes in accordance with revised procedure and optimised the PLC control during the next maintenance shift.
Performance testing of the brakes confirmed the system was now performing as intended. In addition, the client is proceeding with an upgrade to replace the existing loading boot end with a permanent tail braking frame in readiness to relocate the brakes to the tail end after the conveyor has reached its final design length and loading all coal onto the tail.
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Above: SCADA trending data for overrun event
Above: Dynamic analysis of conveyor brake control