1. Misaligned tail pulley: The belt exhibited consistent tracking over the head pulley, indicating that pulley misalignment was not a major concern. However, the tail pulley appeared slightly misaligned, leading to tracking issues.
2. Load conditions and side loading: Side loading at the chutes, particularly in the Course Ore Stockpile (COS) load zone, caused the belt to centralise. This indicated potential side load issues at the chute and the likelihood of tracking issues downstream of the load zone.
3. Seized return tracker: The primary cause of the tracking issues was a seized return tracker near the head pulley. Findings also showed deviation of the trough and return belt position.
4. Additional findings: Additional issues included skive damage to the splice, overall worn and damaged belt condition, improper tail end transition zone adjustment, seized trough trackers in various locations due to material build-up, off-centred return belt and seized return trackers due to carryback and material spillage.

The Solution

Based on the findings from the site assessment, CPS recommended a phased approach to address the tracking issues and reset the conveyor to best practice. The proposed actions included:

Phase 1: Reset Conveyor Status

1. Remove seized trackers: CPS suggested the removal of seized tracking frames (both carry and return) and their potential replacement with inverted vee return frames. The goal was to reduce the number of trackers required and ensure their proper functionality.
2. Adjust tail transition frame: The height of the tail transition frame needed adjustment to ensure proper contact with the center roll. The wing angle also required adjustment to align with the natural belt profile.
3. Check counterweight tension: CPS conducted a static conveyor calculation to measure and verify the counterweight mass. Adjustments were made to match the calculation’s recommendation.
4. Conduct survey of idler frames and pulleys: A survey was recommended to assess the alignment of idler frames and pulleys to a consistent reference point. Misaligned frames were to be adjusted within installation tolerances.

Phase 2: Additional Actions

1. Review design of tail pulley: CPS suggested considering a crowned tail pulley with a fabric belt to improve tracking performance.
2. Design review/redesign of take-up trolley rails and wheels: A redesign of the take-up trolley guide rails and wheels was proposed to eliminate existing issues with the current design.
3. Review chute design: The COS load chute was to be reviewed after implementing the recommended changes to ensure central loading.

The Results

Following the implementation of both Phase 1 and 2 recommended actions, together with the installation of new CPS rollers, idlers and pulleys, all tracking issues with Northern Star’s CV-3 conveyor were successfully resolved. The improvement was instantaneous.

“Thanks to everyone at CPS for your help for your help with not only the supply of an excellent product, but also your advice on the best solution to rectify the issue. This improvement will ensure the longevity of not only the belt, but also the conveyor stringers and trusses. We are extremely happy with the CPS products we have been using, not just in terms of their quality, but also from a cost perspective. The design is simple, but extremely effective. CPS clearly embrace the KISS principle! It’s refreshing to see, especially in a time when many mining companies can be forgiven for being blinded by the ‘flashing lights’ of new technology.” - Northern Star’s Maintenance Planner, Charlie Groat